International Conference on Thermo Mechanical Processing - TMP 2026

20 Oct 2026, 09:00 → 26 Oct 2026, 16:00 Europe/Vienna

Austria Trend Parkhotel Schönbrunn

Hardy Mohrbacher (NiobelCon bvba), Christof Sommitsch (Graz University of Technology)

Tuesday 20 October

13:00 Registration

13:45 Opening

Plenary Talk(s)

1 Niobium effects on thermo-mechanical processes: It takes two to tango

Thermomechanical processing (TMP) in its various forms is the key process for producing modern high-performance steels. TMP typically provides microstructures featuring small grain size, enhanced dislocation density, precipitate particles and secondary hard phases. However, mechanisms such as recovery, recrystallization, grain growth as well as particle coarsening can cause microstructural softening opposing the intended goal of TMP. Several decades of development have resulted in elaborate industrial TMP practices, controlling and limiting these adverse effects. Yet even capable TM processing equipment might be confronted with temperature and deformation schedules that are too challenging for reliably obtaining the desired microstructure and, hence, the required property spectrum under everyday industrial conditions. In this case, dedicated alloy additions are essential to widening the processing window for enabling reproducible and economic production via TMP.
Niobium microalloying has the most prominent role of all alloying elements in TMP by far. CBMM recently celebrated 70 years of activity, understanding the niobium’s physical metallurgical effects, together with our partners. Different than other alloying elements, niobium has grown with no uncertainties of supply and with pricing not subjected to speculations and spikes. Sustainability at CBMM is linked to the environmental impact, the economic aspects of our partners and social recognition. In relation to carbon footprint, we have defined actions to reduce emissions in FeNb production, becoming net zero in 2040, and we can already contribute reducing the steel production’s emission, rebalancing the steel compositions with Nb additions and reduction of other alloying elements. We have real case developed in which we saved between 30 and 100 kg CO2 per ton of steel, with cost reduction. Therefore, this contribution demonstrates CBMM’s efforts in reducing niobium’s carbon footprint as well as in guaranteeing a globally stable supply stream of metal.

Speakers: Dr RAFAEL MESQUITA (CBMM (Director of Technology, CTO)), FABIO D AIUTO (CBMM (General Manager EMEA))

2 High Performance, Low Emissions: The Role of Thermomechanical Treatment in Tomorrow’s Steel Industry

A comprehensive assessment of thermomechanical processing (TMCP) shows advantages for next‑generationcarbon footrprint reduced steel products. Rather than relying primarily on alloying or downstream heat treatments, TMCP integrates controlled deformation, precise temperature management and cooling during hot rolling to engineer microstructure, properties,and sustainability performance simultaneously.

Utilizing the TM effects is offering to provide huge advantages for steel producers and final application industries at the same time,as production costs can be cut as also the number of production steps and hence contribute to lower the carbon footprint of such products.

Speaker: Dr Bernd Linzer (Primetals Technologies Austria GmbH (Technology Officer))

Alloy Interactions with TMP

3 Strategies to Increase Productivity in Hot Rolling of Heavy-gauge Steel Plates Through Integrated Niobium Microalloying and Temperature–Microstructure Modeling

The global demand for heavy-gauge steel plates for infrastructure, wind-tower and line-pipe applications has increased in recent years, and this change in the consumption behavior intensified productivity challenges in rolling mills, particularly when conventional manufacturing strategies are not adapted to the evolving requirements and dimensions. Productivity in hot rolling is usually driven by the interaction between temperature evolution, recrystallization behavior, microstructural control and mill equipment or dimensional constraints. Niobium microalloying plays a key role in expanding the thermomechanical processing window by increasing critical temperatures associated with austenite recrystallization control (RLT and RST), enabling higher rolling temperatures and shorter holding times between rolling stages. In this work, a modeling-based approach combining niobium metallurgy and temperature–microstructure analysis is presented, using the MicroSim® framework, to finetune alloying and process strategies, including through-thickness plate temperature evolution and rolling pass design, targeting controlled final microstructure distribution. The model couples through-thickness temperature evolution, austenite grain size distribution–based evolution, precipitation behavior, allowing a detailed examination of the alloy design and rolling schedule strategy on microstructure, being able to adjust the process efficiency with reduced holding times and transfer bar thickness between rolling stages. Productivity-oriented simulation scenarios were evaluated, focusing on cost-effective thermo-mechanical process of heavy gauge products. The results indicate that productivity improvements can be selectively achieved through incremental niobium additions when combined with a detailed, through thickness definition of temperature and strain evolution, enabling reduced holding times and higher finishing temperatures without compromising microstructural homogeneity, highlighting the importance of holistic design of composition and processing parameters as key lever towards production excellence.

Speaker: Jonatas Venancio Barbosa (CBMM)

4 Nickel’s metallurgical functionalities in TMP processing of structural plate steels

Nickel is an important alloying element in carbon steels, as it significantly enhances hardenability and toughness, particularly at low temperatures. It plays a key role in steel grades for demanding applications such as energy, mining, and defense. While most carbon steels contain less than 1 wt% Ni, cryogenic steels may include up to 9 wt%. In plate production—via normalizing, controlled rolling, or quenching and tempering (Q&T) nickel interacts with processing conditions and other alloying elements, influencing microstructure and mechanical properties. Its effects are discussed in this contribution for steels with yield strengths from 350 to 1500 MPa.
For heavy plates in offshore constructions with demanding toughness requirements (350–460 MPa), typically niobium-microalloyed HSLA steels, nickel additions up to ~1 wt% expand the austenite phase field and delay the austenite-to-ferrite transformation. This leads to increased undercooling, promoting ferrite nucleation and refining the microstructure. At slow cooling rates, the delay also enhances precipitation strengthening, compensating for reduced grain refinement.
In ultrahigh-strength structural steels for highly stressed constructions, produced by reheat quenching or direct quenching, sufficient hardenability is required to achieve martensite in thick plate centers. Nickel additions to Mo- or Mo–B alloy systems significantly improve hardenability, especially at low cooling rates, while also increasing toughness—an advantage for mining and defense applications.
For cryogenic applications, like LNG-applications, so-called „9% Ni steels“ provide a cost-effective alternative to austenitic steels. In addition to solid solution softening by nickel alloying primarily accounting for the improvement of low temperature toughness, the Q&T treatment results in a very fine grain structure. Nickel partitioning stabilizes a small fraction of retained austenite during tempering at temperatures in the two-phase region between the Ac1 and Ac3 temperatures. An optimized retained austenite content results in exceptionally high toughness at temperatures below −100 °C.

Speaker: Andreas Kern (thyssenkrupp Steel Europe)

Recrystallization, Precipitation and Phase transformation

5 Mixed Microalloy Precipitate Evolution in Austenite

There is a continuing demand to develop steel with improved mechanical properties and to lower production cost. Microalloyed or high-strength low-alloy (HSLA) steels are widely used in a variety of applications due to a favorable combination of cost and mechanical properties. The proper design of steel alloys for a multitude of applications in which grain size refinement is necessary to promote mechanical performance requires a fundamental understanding of the influence of microalloy precipitate evolution during thermomechanical controlled processing. This contribution focuses on HSLA steels containing multiple microalloying elements (Nb, Ti, and V), as it was found that under certain processing conditions, mixed precipitates can be very fine, homogeneously distributed in the steel microstructure, and resistant to coarsening at elevated temperatures, which is beneficial for mechanical performance.

Speaker: Emmanuel De Moor (Colorado School of Mines)

6 Austenite Conditioning of Hot Rolled Microalloyed Low-Carbon Steels

Thermomechanical controlled processing (TMCP) is critical for the production of state-of-the-art hot-rolled microalloyed low-carbon steels. The precise control of recrystallization and austenite grain size distribution under industrial TMCP is essential to optimize rolling schedules and product consistency.
The present study includes the characterization of austenite formation and grain growth during reheating of as-cast slabs where in Ti-Nb microalloyed steels heterogeneous grain structures with a mixture of small and very large grains were observed due to local variations in the distribution of Ti-rich carbo-nitrides. These grain structures are significantly homogenized and refined through recrystallization in hot rolling as shown with laboratory hot torsion simulations. Interrupting the deformation schedule with water quenching captured microstructural evolution during rolling simulation. Electron backscatter diffraction (EBSD) was used to characterize microstructures and reconstruct prior austenite grain (PAG) structures. Further, laser ultrasonic measurements were established to in-situ quantify recrystallization kinetics by monitoring austenite grain size evolution in hot compression testing. These in-situ measurements reduce the need for labor intensive ex-situ investigations of austenite recrystallization and provide clear evidence of the degree of recrystallization as verified with conventional double-hit tests. In particular, the conditions for partial and/or no recrystallization can be identified with laser ultrasonics. Based on these experimental studies a recrystallization model is adapted that accounts for recovery and strain-induced precipitation of Nb-rich carbo-nitrides.
The advances of laboratory hot deformation simulations in combination with EBSD-based austenite reconstruction and in-situ laser ultrasonic recording provide a powerful methodology to expedite the development of microstructure evolution models for industrially relevant hot rolling conditions.

Speaker: Matthias Militzer (The University of British Columbia)

15:40 Coffee Break

Alloy Interactions with TMP

7 Influence of NbC Precipitate Size Distribution on Pipe Seam/Girth Weld HAZ Austenite Grain Size Control in API X70 heavy gauge plates

Heavy‑gauge wide API X70 plates (25–28.2 mm) were developed at JSW Plate Mill through a combination of optimized Nb‑based microalloying, enhanced thermo‑mechanical controlled processing (TMCP), and accelerated Multi-Purpose Interrupted Cooling (MULPIC) cooling to achieve stable strength and low‑temperature ductility. Drop Weight Tear Test (DWTT) performance exceeded 85% shear at 0 °C for all heavy‑gauge plates. Process trials demonstrated that increasing the total metallurgical reduction ratio from conventional values of 5.2-5.6 to 7.3-8.0 enabled stable DWTT performance at 0 °C in heavy‑gauge plates. MicroSim-PM v10.0 optimization indicated that further increasing the reduction ratio to approximately 9.7–10.7, combined with lower reheating temperatures (1200–1210 °C), increased finishing mill reductions (≈70%), and lower cooling stop temperatures, is expected to improve austenite grain size homogeneity (ZD reduced from ~6.7 to ~3.0) and extend stable DWTT performance to −10 °C. Transmission electron microscopy (TEM) based precipitation analysis on representative plates of thickness 25.4 and 28.22 mm identified multiple Nb–Ti–rich precipitate populations, including non‑dissolved precipitates (>100 nm), strain induced precipitates (>10 – ≤100 nm) that started as fine strain induced precipitates at the end of the roughing/beginning of finishing and then coarsened during the remaining finishing passes, and fine strain induced precipitates (≤10 nm) that formed at towards the end of finishing and did not have sufficient time or processing parameters to coarsen. The mean size of fine precipitates (≤10 nm) was similar in both the thickness.
Comparison of the JSW results with published data from other steel producers worldwide suggests that the appropriate NbC precipitate size distribution can play an important role in controlling pipe seam/girth weld HAZ austenite grain growth behavior and corresponding HAZ ductility and hardness.

Speakers: Joao Paulo Souto (CBMM), Mr Subhnit Roy (JSW Group)

8 Effect of Niobium Microalloying on Recrystallization Kinetics, Precipitation, and Mechanical properties in Low-Carbon, Low-Alloyed Steels

This study investigates the effect of niobium microalloying on the recrystallization kinetics, precipitation, and mechanical properties of low carbon steels. The experimental materials consisted of three laboratory cast and laboratory rolled steel grades, where the niobium content was the only variable. Used cooling method in these steels was coiling. The experimental work included a wide series of tests using the Gleeble 3800. Relaxation tests were performed at different temperatures, strains and strain rates to study recrystallization kinetics. Coiling simulations with different holding temperatures were also carried out to study microstructure development during controlled cooling. These Gleeble coiling simulation results were compared with the laboratory rolled coiled materials. Mechanical testing was used to see differences in properties between the steel alloys. Microstructural characterization with FE-SEM and EBSD provided information on grain size, microstructural changes and recrystallization kinetics. The results show that increasing niobium content clearly delays or stops recrystallization due to the combined effects of solute drag and precipitation. The niobium content change was affecting also other results. When niobium was increasing hardness and strength was increasing and microstructure changed to more bainitic.

Speaker: Ms Katariina Lehtola (University of Oulu)

9 The Sustainable Production of Vanadium and its Application in TMP Steels and Other Alloys

Microalloying elements are of critical importance in the production of Thermo-Mechanically Processed (TMP) steels. Due to the high solubility of vanadium carbo-nitrides, V(CN), vanadium microalloying is suitable for a wide range of steels, ranging from ultra-low carbon automotive steels to medium carbon steels for forgings and reinforcing bar, high carbon rail steels and ultra-high carbon rod. The high solubility of V(CN) also allows the use of reduced reheating temperatures prior to rolling, giving significant energy savings. The strengthening effect of vanadium can be increased in certain steel types by using higher nitrogen levels; the synergistic combination of vanadium and nitrogen allows for reduced overall alloying additions. The use of higher strength vanadium containing steels has considerable environmental benefits, allowing for reduced amounts of steel to be used.
Vanadium resources are widely distributed around the world; China, Russia and South Africa are major producers, but new reserves are being exploited in other countries such as Australia. Vanadium production methods can be classified into three main categories, depending on the type of the vanadium reserve: vanadium produced as a co-product from steel production when appropriate iron ores are processed; vanadium produced by the processing of industrial waste such as spent catalysts; and vanadium produced from directly mined ore, such as magnetites rich in vanadium and titanium.
The suitability of vanadium for many steel types, the wide geographical distribution and varied production methods means that vanadium can be considered a robust and sustainable microalloying element.
As well as being of vital importance in TMP steels, vanadium is also a critical alloying element in advanced titanium alloys, and vanadium alloys are being considered for applications in nuclear fusion reactors.
Increased use of vanadium in high strength steels is predicted, and the growth of alternative applications will lead to increased vanadium demand worldwide.

Speaker: Dr David Crowther (Vanitec)

10 Effect of combined Nb-V microalloying in mechanical behavior of rebars

The achievement of yield strength levels above 460 MPa with ferrite-pearlite microstructures in medium carbon rebars requires, in addition to appropriate microstructural refinement, a certain contribution of precipitation strengthening. In addition to the minimum strength, a proper balance between TS and YS and good low cycle fatigue behavior can be other requirements that should be considered, mainly in seismic conditions. These multiple combinations of properties require an appropriate combination of chemistries with hot rolling/cooling strategies that include the addition of microalloying. On the other hand, the increasing trend to apply direct charging processing route, in many cases followed by short induction reheating cycles prior to hot rolling, introduces additional challenges about microalloying elements, partially precipitated or fully in solution at the entry of the first rolling pass.
The traditional approach has been to focus on the precipitation strengthening provided by V microalloying to achieve the mechanical characteristics. In this context, recent studies on small additions of Nb to V microalloyed rebars show new options to better achieve the mechanical requirements and improve the robustness of processing conditions. First, Nb modulates the austenite evolution during hot rolling and before transformation, mainly by its solute drag effect on recrystallization kinetics and grain growth. Second, Nb in solution increases hardenability during transformation. This also affects the interphase precipitation of V(C,N). The result is that there is a synergistic interaction between Nb and V that significantly increases the contribution of precipitation strengthening.
This paper focusses on these synergistic aspects of Nb and V, including how hot charging conditions, combined with tramp elements from scrap, can affect their function during processing.

Speaker: Joao Paulo Souto (CBMM)

Recrystallization, Precipitation and Phase transformation

11 In Situ Monitoring of Texture Evolution During Thermal Treatment

Laser ultrasound is a non-contact method that enables continuous monitoring of elastic properties in steel samples during thermal processing. Compared with conventional metallographic techniques, it offers substantially higher sample throughput and therefore faster evaluation of relevant process parameters. In this work, we present an approach for in situ estimation of the recrystallization state during recrystallization of cold-rolled steel samples.
The experiments were carried out using an inductive heating thermal simulator whose chamber was adapted for laser-ultrasonic generation and detection through optical windows. An excitation laser locally heats the sample surface, thereby generating ultrasonic waves, while a second laser, integrated into an interferometric detection system, captures the resulting resonances. These signals enable the determination of elastic parameters, which serve as input for subsequent modeling. The measurements were performed on rolled sheet steel samples with a diameter of 62 mm. The method allows elastic property changes to be tracked continuously throughout the thermal cycle. In addition, line shaped excitation of the laser ultrasound makes it possible to measure changes in elastic anisotropy, providing sensitivity to the evolution of crystallographic texture during heat treatment.
The experimental results were compared with simulations and models based on EBSD data. This combination of in situ measurement and microstructure-based modeling enables a deeper understanding of the relationship between recrystallization, texture evolution, and elastic response. The results demonstrate that laser ultrasound is a promising tool for real-time monitoring of thermally induced microstructural changes in steel.
Due to its non-contact operation, high measurement speed, and applicability under industrially relevant conditions, the method also shows strong potential for future inline implementation in thermal processing lines.

Speaker: Edgar Scherleitner (Research Center for Non Destructive Testing GmbH - RECENDT)

12 Niobium precipitation strengthening potential and correlated physical-metallurgical phenomena

Niobium being a strong carbide former has the propensity of significantly contributing to strength increase by dispersing copious ultra-fine particles in the iron matrix. According to the well-known Ashby-Orowan theory, a homogeneous particle dispersion with closest inter-particle spacing results in the highest strength contribution. From that point of view, it is important to understand how NbC precipitates nucleate and which are the ideal thermo-mechanical processing conditions to achieve the best strengthening potential. In this contribution, a variety of thermo-mechanical treatments will be presented for analyzing the strengthening contribution of niobium precipitation in different low carbon steels. A method to derive precipitation strengthening from the true stress-strain curve originating from tensile testing will be detailed. This one allows identifying direct influences of precipitates on the early yielding behavior and the subsequent Lüders deformation. Applying this methodology to a large variety of niobium microalloyed low carbon steels resulted in a robust data set indicating the expectable precipitation strengthening capability under various processing conditions. The data reveal that the strengthening contribution most typically is in the range of 150-180 MPa. Under particular processing conditions a strength increase of 200-220 MPa could be achieved. These findings based on tensile tests are complemented by transmission microscopic analysis. Evidently, the particle distribution is related to the thermo-mechanical processing history. While adding more niobium to the alloy does not necessarily further augment the strength the combination with other alloying elements can have a positive effect. The gathered insights allow working out recommendations for reliable alloying and processing concepts optimizing precipitation strengthening.

Speaker: Hardy Mohrbacher (NiobelCon bvba)

13 Solubility of Microalloying Carbides in Steels: A Critical Review and Novel Aspects

It is the nature of microalloying elements, primarily Ti, Nb, and V, to form stable carbide and nitride compounds with interstitial carbon and nitrogen present in the steel matrix. The resulting fine-sized compound particles have the potency to retard or prevent phenomena such as recovery, recrystallization and grain growth. The controlled microalloy precipitation during thermomechanical processing is the basis for generating dedicated microstructural features resulting in advanced properties of such steels. Microalloy solubility in steel is determined by the solubility product, representing the maximum solute content (carbides/nitrides) in austenite or ferrite. Solute concentration increases exponentially with temperature. Initially, it is the aim to redissolve microalloy compounds ahead of hot processing to activate the microalloying elements for the subsequent processing steps. Therefore, it is decisive to define a sufficiently high soaking temperature for redissolving the microalloy compounds as much as possible. In later processing stages, on the contrary, it is often desirable to prevent dissolution of existing microalloy particles. In either case, the solubility product is the fundamental criterion determining the stability of microalloy compounds. Over the more than five decades that microalloying technology is in use many solubility products have been developed that, however, do not result in a unique dissolution temperature for nominally the same microalloy compound. This can be the consequence of the measurement technique used to determine the amount of dissolve microalloy as well as the presence of other alloying elements in the steel. This contribution critically reviews available solubility products in austenite and ferrite addressing the potential origins of variation. Furthermore, novel aspects of microalloy solubility in the intercritical ferrite range including the possible consequences for microstructural control will be discussed.

Speaker: Mr Caio de Paula Camargo Pisano (CBMM | Niobium)

14 Dynamic recrystallization and precipitate evolution in high strength Al7068 alloy during high temperature deformation: A TEM study

Thermomechanical processing, particularly hot compression, is widely used to tailor the microstructural and mechanical properties of aluminium alloys. Hot compression behaviour is commonly interpreted through true stress–true strain curves and microstructural evolution, especially grain refinement and orientation relationships. The nature of the true stress–true strain response is strongly influenced by deformation parameters such as temperature, strain rate, and strain, while dynamic recrystallization is governed by the kinetics of dislocation motion under these thermomechanical conditions. In general, the characteristics of true stress–true strain curves are associated with dynamic recrystallization. However, in precipitation-hardenable alloys, the flow behaviour is also significantly affected by precipitate evolution, including changes in precipitate size and distribution. Moreover, thermomechanical processing of precipitation-strengthened alloys is challenging due to the increased risk of material failure.
In hot-compressed Al7068 alloy, TEM analysis showed a consistent increase in precipitate size with increasing temperature and decreasing strain rate. The precipitate size nearly doubled with a 100°C rise in temperature (at a strain rate of 1 s⁻¹) and increased approximately fourfold when the strain rate was reduced from 1 s⁻¹ to 0.001 s⁻¹. This variation in precipitate size closely correlates with changes in the flow stress of the deformed material. Furthermore, the evolution of precipitate phases during hot deformation promotes a more uniform distribution of phases throughout the alloy, which can significantly enhance the overall material properties.

Keywords: Precipitate evolution, Al7068, thermomechanical processing, TEM

Speaker: Dr Nitish Raja (Indian Institute of Technology Patna)

15 Hot Deformation Behavior of a Medium-Carbon Mo–Cr–V–Nb–Ti–B Steel

The hot deformation and static softening behavior of a commercial medium-carbon Mo–Cr–V–Nb–Ti–B steel used in seamless tube applications was characterized using single-hit and double-hit compression tests on a Gleeble 3500 thermomechanical simulator. Single-hit tests were conducted at deformation temperatures from 900°C to 1200°C, strain rates of 1, 5, and 10 s⁻¹, to a true strain of 0.5, using two reheating temperatures of 1200°C and 1250°C. Mean flow stress (MFS) values were derived and compared against chemistry-based correlations of the Misaka–Yoshimoto, Kang, and Bruna families. While measured MFS fell within the range of existing correlations at high temperatures, it progressively deviated toward higher-stress models below 1000°C, with the deviation increasing at lower strain rates. Reheating temperature had no effect on MFS across the full temperature range investigated.
To interpret this reheating-temperature insensitivity, precipitation evolution during the simulated thermal cycle was modeled using TC-PRISMA. Under a nitrogen-locked scenario, undissolved Nb(C) precipitates at 1200°C reheating were too coarse (~30 nm) to contribute Orowan strengthening, while complete Nb dissolution at 1250°C reheating produced negligible re-precipitation volume fractions above 950°C, yielding effectively zero precipitation hardening at both reheating conditions.
Double-hit tests at 5 s⁻¹ revealed markedly sluggish static recrystallization at 1000°C and 950°C. TC-PRISMA modeling with deformation-enhanced dislocation density confirmed strain-induced Nb(C) precipitation at these temperatures sufficient to suppress recrystallization, while negligible precipitation fractions at 1050°C and 1100°C attributed a transient softening slowdown at ~100 s to experimental scatter. Constitutive flow law parameters were determined from the hyperbolic-sine Arrhenius formulation.
These results define the temperature window where existing MFS correlations cease to apply for this chemistry, provide quantitative flow and softening data for a poorly represented grade family, and offer direct guidance for finishing-mill pass schedule design.

Speaker: Farid Hassani (US Steel)

17:50 WELCOME RECEPTION

Wednesday 21 October

Plenary Talk(s)

16 The production of sustainable, high-quality thin sheet grades via the EAF route as a new challenge for the steel industry

The transition to sustainable steel production presents a significant challenge for the steel industry in the coming decades. The initial stage involves partially replacing the traditional blast furnace and basic oxygen furnace with electrical arc furnace technology. The type and quantity of raw materials (scrap, direct reduced iron, and hot metal) not only determine the CO2 footprint but also influence subsequent manufacturing steps necessary to produce premium thin sheet grades.
In the presentation, the effects of tramp elements on metallurgical mechanisms such as recrystallization and phase transformations will first be discussed. Subsequently, these effects will be analyzed in combination with the processing parameters detailing their implications on material properties.
Since elevated levels of tramp elements generally result in increased strength—and fluctuations in these content levels within scrap contribute to greater variability in properties—appropriate strategies will be outlined to ensure consistent performance and property uniformity, comparable with outcomes achieved using the blast furnace and basic oxygen furnace routes.

Speaker: Dr Andreas Pichler (voestalpine Stahl GmbH (Head of R&D in the business unit Coil))

Intelligent Manufacturing

17 Prediction of Mechanical Properties in Automotive Hot-Rolled Steel Coils based on Position-Specific Cooling History and Process Data Mapping

In the modern steel industry, using large process datasets to improve quality control and production efficiency is an essential engineering task. This study focuses on predicting the main mechanical properties—yield strength (YS), ultimate tensile strength (UTS), and elongation—of hot-rolled steel coils for automotive parts. For these components, consistent material quality is critical for manufacturing stability. To achieve accurate results, we developed a data-linkage model that integrates variables from the entire production line, from the initial chemical composition to the final cooling process in the yard.
A key part of this research is the estimation of the cooling history during yard storage. Since the steel is stored in an as-coiled state, the cooling rate differs significantly depending on the radial and longitudinal positions within the coil. To reflect this, we estimated specific thermal profiles for the inner and outer laps, considering the heat transfer characteristics of the as-coiled configuration. This thermal data was then linked to the model through precise data mapping, which connects parameters from the steelmaking and rolling stages to their exact locations within the finished coil.
The model uses over 30 process parameters, including alloy elements, cooling rates on the run-out table (ROT), and coil dimensions. By matching these variables to their specific positions along the strip, the model can estimate material properties across the entire length and width of the coil. This "full-body" approach helps engineers evaluate internal property deviations that are difficult to measure through standard destructive tests. The results show that this method, combining localized cooling history with systematic data mapping, is a practical tool for managing material consistency and optimizing hot rolling parameters in real production environments.

Speaker: Dr JAEHYUN CHOI (POSCO)

18 Through Process Modelling of Steel Production in Štore-Steel Company

A part of the digitalisation efforts in the steel industry concerns the numerical optimisation of the steel production chain to increase quality, productivity, and sustainable production. We present the computational modelling of the steel processing route at Štore-Steel, comprising continuous casting, controlled cooling, annealing, reheating, reverse and continuous hot rolling, cooling bed, and heat treatment. The modelling concept is based on the Hybrid Integrated Computational Materials Engineering (ICME) approach, composed of a combination of Horizontal ICME, where the simulation codes for different processing or product usage steps are connected with their associated multiscale structures and material properties, and Vertical ICME, where the simulation codes at multiple length scales are involved in describing the product properties. The scales we cope with range from the grain size to several tenths of a meter. We present novel solution methods for describing the related multiscale and multiphysics thermomechanical problems. The microstructure is formulated using the phase-field method, the mesostructure using the cellular automaton method, and the macroscopic electromagnetic, fluid mechanics, and solid mechanics fields using continuum mechanics concepts. We elaborate on a space-time adaptive meshless solution based on collocation with radial basis functions for solving the microscopic and macroscopic scales and the point automata concept for solving the mesoscopic scale. The phenomena addressed by this novel meshless technique range from large-eddy simulation of continuous casting to elastoplastic deformation of products on the cooling bed. The validation of the models, based on plant and laboratory measurements, is shown. A coupling of physical models with artificial intelligence for optimisation of quality, energy, and productivity is presented.

Speaker: Prof. Božidar Šarler (University of Ljubljana)

19 Artificial Intelligence Empowered Processing of Metallic Materials: Challenges and Perspectives

Artificial intelligence is increasingly reshaping metallic materials design by accelerating exploration beyond conventional trial-and-error approaches. However, purely data-driven models often suffer from limited interpretability, excessive data requirements, and poor generalization across different alloy systems/processing routes. This study presents a physically guided AI framework for intelligent metallic materials design and processing, with a focus on steels and other high-performance structural alloys. By systematically embedding physical metallurgy knowledge into machine learning models, a multi-level strategy is established, spanning thermodynamics-informed learning, microstructure-centered deep learning, and mechanics-guided transfer learning. Thermodynamic and solidification-related descriptors are first incorporated to capture processing-dependent phase evolution, significantly improving prediction accuracy and alloy design rationality under limited data conditions. For complex, processing-induced microstructures, deep learning models guided by SEM/EBSD knowledge and multimodal imaging are developed to enable robust classification, quantification, and property prediction directly from microstructural images. Furthermore, physics-guided transfer learning frameworks integrating fatigue and creep mechanisms allow reliable prediction of property curves and long-term performance while reducing experimental cost. Representative applications are demonstrated in advanced steels, nickel-based superalloys, and aerospace and energy alloys. Overall, this work highlights how coupling physical metallurgy and processing physics with AI enhances accuracy, interpretability, and transferability, paving the way toward reliable, industry-ready metallic materials design.

Speaker: Prof. Wei Xu (Northeastern University)

20 A Hybrid AI Approach for Rolling Force Prediction in Plate Mills: Integrating Machine Learning Technique with Metallurgical Simulation Variables

Accurate rolling force prediction in flat hot rolling is essential for precise gap control, shape stability, and equipment protection, operating within mill power and force limitations. In practical hot rolling operations, the prediction of rolling forces is challenged by the combined effects of evolving deformation geometry and different metallurgical phenomena such as recrystallization, recovery, strain accumulation, precipitation of particles and thru-thickness temperature evolution, resulting in different material responses from pass to pass.
This work proposes a physics-informed hybrid machine learning framework that combines production process raw data with metallurgical features computed by a microstructural simulation tool (MicroSim®) to predict rolling forces. Feature engineering is structured in two layers: (i) physically derived variables, including contact length, and shape factor, and (ii) pass-level with austenitic grain size distribution, recrystallized fraction, accumulated strain, and metallurgical mean flow stress (MFS). The MFS acts as a physics anchor, providing the model with theoretical baseline resistance of the material and shifting the learning task toward correcting deviations from physical metallurgy.
A gradient boosting algorithm (XGBoost) was benchmarked, across an industrial dataset, in two configurations: a pure data-driven baseline and the proposed hybrid model. The hybrid model consistently outperformed the baseline in accuracy and generalization, with feature importance analysis confirming that microstructural variables ranked among the dominant predictors, validating the physical consistency of the approach.
These findings indicate that combining process data with thermomechanical simulation outputs provides a robust tool for rolling-process prediction, directly supporting improved control and enhanced product quality.

Speaker: Mr Jackson Carvalho (CBMM)

TMP Strategies for Advanced High Strength Steel

21 Effects of Temperature and Deformation on Austenite Grain Size and Phase Transformations in Advanced High Strength Steels

Thermomechanical processing (TMP) implies rigorous design, careful control, and optimization of microstructure through combinations of deformations and phase transformations to obtain desired final microstructure and end properties of products. Deformation operations that may include hot, warm, and cold forming can be in general combined with multiphase and single phase (e.g., recrystallization) transformations.
One of the most important characteristics of microstructure in steels is the austenite grain size that influences both deformation and transformation behaviors, as well as their coupling. In the present work, mechanisms and kinetics of grain growth and recrystallization in austenite, as well as their effects on phase transformations in cooling of several Advanced High Strength Steels were studied using Confocal Laser Scanning Microscopy (CLSM), SEM and EBSD techniques. Evolution of austenite grain structure was monitored in situ during reheating, soaking at temperatures up to 1200oC (with and without deformation) and during subsequent cooling including that under load. Depending on steel chemistry and austenite grain size distribution attained upon reheating various grain growth mechanisms were revealed, including conventional grain boundary (GB) migration, GB bulging, dissociation of lower energy GBs, especially under deformation, evolution of triple junctions, the combinations of the above, etc. Dynamic recrystallization in austenite under different deformation conditions was detected with mechanisms naturally depending on grain size prior to deformation, GB energy and steel chemistry. The impacts of above factors on types and kinetics of phase transformations and on the variability of resultant microstructure are discussed. Limitations of CLSM technique with respect to TMP design are also addressed.

Speaker: OLGA GIRINA (ArcelorMittal)

22 Mechanical and microstructural properties of low carbon bainitic steels subjected to different controlled cooling strategies

The transition from conventional steelmaking to fossil-free production promotes more continuous processing and reduces flexibility in chemical compositions, increasing the need to produce multiple strength grades from a single alloy. This study examines the feasibility of achieving several steel strength grades from one chemical composition by varying the cooling method. Two laboratory-melted low-carbon steels containing 0.045 C (in wt.%), 0.5 Si, 1.2 or 1.5 Mn and scrap-derived residuals of copper, nickel, and chromium were thermomechanically processed using three cooling routes: (1) air cooling (3.2 °C/s) to room temperature, (2) interrupted accelerated cooling (15 °C/s to 500 °C, then 0.027 °C/s), and (3) direct quenching (35 °C/s) to room temperature. Tensile testing, impact toughness testing, field emission scanning electron microscopy, electron backscatter diffraction, and dilatometry were used to characterize mechanical properties, microstructure, and phase transformation behavior. Direct quenching produced a microstructure consisting of 95% bainite and 5% martensite/austenite (M/A). With successful interrupted accelerated cooling, bainite and M/A fractions changed to 99.5% and 0.5%, respectively. The more complete bainitic transformation increased yield strength. A variation of 50 °C in finish cooling temperature significantly affected yield strength. An increase in Mn content had a negative effect on impact toughness. Generally, impact toughness increased when cooling rate increased due to the formation of a more complex microstructure. One composition can be used to produce 420, 460 and 500 MPa yield strength steel grades.

Speaker: Tommi Hintsala (University of Oulu)

23 An ICME Framework for Integrated Alloy Design and Thermomechanical Processing of Nano-Bainitic Steels

The development of nanobainitic steels requires the simultaneous optimization of alloy composition and thermomechanical processing routes to achieve targeted microstructures and mechanical properties. This inherently demands a coupled understanding of material behavior across both macroscopic and microscopic scales. In this work, an Integrated Computational Materials Engineering (ICME) framework is developed to link computational alloy design, thermomechanical processing, and microstructure evolution within a unified simulation environment.

Alloy design is performed using CALPHAD-based tools such as Thermo-Calc, where compositions are selected based on phase stability and transformation temperatures relevant to bainitic microstructure formation. The resulting compositions are then used to define temperature-dependent material properties for macroscopic process simulations. Thermomechanical processing, including forging following casting, is simulated using Abaqus, incorporating user-defined subroutines to account for phase transformation and grain evolution.

The local thermo-mechanical history (temperature, strain, and strain rate) obtained at each material point during processing is transferred to microstructure models. Precipitation kinetics, including carbide and intermetallic phase formation, are modeled using MatCalc, while microstructure morphology evolution is captured using MICRESS. In addition, segregation profiles derived from solidification simulations are incorporated to account for chemical inhomogeneities and their influence on subsequent microstructure evolution.

All simulation steps are coupled through an automated Python-based workflow, enabling consistent data transfer across length scales and process stages. The framework enables the prediction of key microstructural descriptors, including phase fractions, prior austenite grain size, dislocation density, and precipitation state, along with corresponding mechanical properties after forging. The approach further allows optimization of alloy composition and process parameters to balance mechanical performance with downstream manufacturability requirements.

This work demonstrates a scalable ICME methodology for the integrated design of alloys and thermomechanical processing routes for advanced bainitic steels.

Speaker: Karthik Ramalingam (IEHK - RWTH Aachen University)

24 Microstructures and mechanical properties of borides reinforced lightweight steels

This study investigates a lightweight steel with enhanced elastic modulus via borides reinforced particles. The microstructure consists of an austenitic matrix containing δ-ferrite and 13% TiB₂ particles. The steel exhibits a yield strength of 430 MPa, tensile strength of 630 MPa, elongation of 13.5%, elastic modulus of 225 GPa, and density of 6.98 g cm⁻³. The heterogeneous as-hot-rolled microstructure—equiaxed austenite with elongated δ-ferrite bands and micron-sized TiB₂—enables a favorable combination of physical and mechanical properties. The improved strength-ductility balance is attributed to δ-ferrite’s dual role: high dislocation density provides strengthening through a composite effect, while the soft/hard phase contrast with austenite promotes strain hardening via geometrically necessary dislocations. This work offers a cost-effective route for large-scale production of low-density steels with high stiffness, strength, and ductility.

Speaker: Dr Yinghua Jiang (Research Institute of Technology, Shougang Group Co., Ltd)

10:20 Coffee Break

Microstructure & Properties

25 Metallurgical engineering of a new molybdenum prehardened steel for plastic injection moulding and mechanical applications

There is a growing demand for tool steels in plastic moulding and mechanical engineering that combine high performance, durability, and cost efficiency while reducing energy use and CO₂ emissions. Currently available prehardened steels are limited to 30–40 HRC. For higher hardness, grades such as 1.2343/1.2344 (H11/H13), originally designed for hot-working processes like forging, die casting, and hot stamping, are often used. These grades are supplied in a ductile, annealed condition to facilitate machining but require final heat treatment by quenching and multiple tempering steps, which can cause substantial shape distortions or cracking and increase production time and cost compared with parts made directly from high-quality prehardened steel. However, implementing these prehardened grades for thick sections involves challenges such as managing mechanical property heterogeneities across the thickness, caused by microstructural variations linked to cooling gradients after austenitization. This cooling gradient often results in microstructures containing significant amounts of retained austenite at the core of the plate. Such conditions raise important questions regarding the influence of alloying elements on the stability of retained austenite, and its effect on carbide precipitation. This work therefore focuses on studying the effect of molybdenum on retained austenite decomposition and carbide precipitation during tempering in the framework of developing new steel grades with initial bainitic/martensitic microstructures. An in-situ HEXRD analysis was performed to follow the evolution of major phase mass fractions and their carbon content. Ex-situ small-angle neutron scattering permitted the study of the precipitation of small carbides population and linked it with hardness.

Speaker: Jules Audard (ArcelorMittal Industeel)

26 In-situ HEXRD study of negative thermal expansion and martensitic transformation in water quenched and cold rolled TiNbTa alloys

α″-martensitic Ti alloys display customizable thermal expansion, making them attractive for applications in precision optics, metrology, and semiconductor lithography, where dimensional stability under varying temperature is critical. The bulk thermal expansion of polycrystalline components is governed by the magnitude and anisotropy of the lattice thermal expansion, volume fraction and crystallographic texture of the α″ phase, all of which are customizable through the type and the concentration of β-stabilizing alloying elements and through thermomechanical processing.
Nb, a β-stabilizer in Ti alloys, directly influences the lattice thermal expansion of α″-martensite and its transformation temperatures, making binary Ti-Nb alloys the primary focus of thermal expansion studies to date. Ta is likewise a β-stabilizer but has received far less attention, despite its higher melting point and its potential to enhance the stability of α″-martensite. The present work examines how thermomechanical processing influences microstructure, lattice-level and bulk thermal expansion of α″-martensitic TiNbTa alloys, by comparing water-quenched and cold-rolled states. Three Ti alloys with varying Nb and Ta content were arc-melted, homogenized, and water-quenched to produce α″-martensitic microstructures. They were then cold-rolled to induce crystallographic texture leading to negative thermal expansion along the rolling direction. Laboratory X-ray diffraction (XRD) was employed to characterize the resulting texture. In-situ high-energy XRD at the German Electron Synchrotron (DESY) was used to track the evolution of phase fractions, lattice parameters and lattice thermal expansion during heating. Transformation temperatures were identified by differential scanning calorimetry, and macroscopic thermal expansion was measured by dilatometry. Cold-rolling induces a pronounced shift in bulk thermal expansion: whereas water-quenched alloys exhibit 5–6 ppm/°C, the strong ⟨010⟩α″ texture developed along the rolling direction yields a negative thermal expansion of ~−30 ppm/°C. Altogether, this methodology establishes the impact of processing by water-quenching versus cold-rolling on the macroscopic thermal expansion and thermal stability of these novel ternary alloys.

Speaker: Mahbod Golrang (KU Leuven)

27 Using a high-speed camera to understand edge cracking during thermomechanical processing of lightweight Fe-Mn-Al-C steels

Previously, some of the problems of cracking as well as edge cracking during two phase thermomechanical hot rolling (e.g. duplex stainless, high Mn steels) have been attributed to the effect of hot ductility, difference of flow behaviour between the different phases. There is limited work and knowledge regarding the exact cracking mechanism as a function of rolling pass number, temperature, mean flow stress or reduction percentages. Using a high-speed camera during the rolling process, it is possible to address this and extract valuable information for optimizing the rolling process for such steels.

In a lab environment, a high-speed camera setup was used while rolling high manganese and aluminium steel concepts (Fe-Mn-Al-C alloys). Data such as crack initiation, crack propagation with each rolling pass were obtained for various rolling schemes, considering different reduction ratios, started rolling temperatures etc. Information from such experimental schemes was analysed based on alloying composition and thermodynamic equilibrium diagrams in the rolling temperature regions. Process maps were created incorporating data from the high-speed camera and phase equilibrium information. Insights from such studies were used to avoid edge cracking in some alloy compositions by adjusting the thermomechanical processing parameters during rolling. Such studies can be used to further optimize processing of such alloys or variation in alloying elements to avoid such dual phase regimes which are prone to hot ductility.

Speaker: Dr Aniruddha Dutta (ArcelorMittal Global R&D Gent)

28 Achieving Consistent High DWTT Performance in TMCP API X70 Plates: Linking Microstructure Control to Fracture Resistance

Abstract

Drop Weight Tear Test (DWTT) performance is a critical indicator of fracture resistance in high-strength pipeline steels, directly reflecting the ability to resist brittle crack propagation. In thermo-mechanical controlled processing (TMCP) of API X70 plates, achieving consistently high DWTT shear values under industrial conditions remains a significant challenge due to variations in microstructure and process parameters.

This study presents an industrial investigation of DWTT performance in API X70 plates produced in a 4900 mm heavy plate mill. The work focuses on the relationship between microstructure evolution and fracture behavior, with particular emphasis on grain refinement, phase distribution, and steel cleanliness.

An integrated optimization approach was implemented, combining controlled alloy design, Ti/N ratio management for effective grain boundary pinning, improved inclusion control, and optimized rolling and accelerated cooling conditions. These measures promote a fine ferritic–bainitic microstructure while minimizing brittle constituents that can initiate cleavage fracture.

Industrial validation demonstrates that the optimized process achieves DWTT shear values above 95% at −20°C with stable mechanical properties. The results confirm that consistent fracture resistance in TMCP plates can be achieved through coordinated control of metallurgical design and process parameters.

This study highlights the critical role of microstructure engineering in fracture performance and provides a practical framework for achieving reliable DWTT performance in industrial plate production.

Speaker: Amin Asiaban (Iron and Steel Affairs, Espadana Industrial Investment Group, Tose’e Farayand San’ati Mehregan – TFSM (Industrial Process Development Company))

TMP Strategies for Advanced High Strength Steel

29 Hidden Sustainbility Potential of Medium Manganese Alloys through Tailored Processing

Medium manganese steels are capturing global attention as intellectual and potential industrial frontiers converge to unlock their exceptional mechanical versatility. In this study, we focus on a single composition (Fe–0.4C–6Mn–2Al–1Si–0.05Nb) to explore the full spectrum of its performance potential through diverse thermo-mechanical processing routes. By tuning phase stability, dislocation structures, and transformation behavior, we achieved a wide range of strength–ductility combinations without altering the chemical composition. Remarkably, the mechanical response spans from ultra-high strength (~2000 MPa) with ~20% elongation to a balanced profile of 1000 MPa strength and 50% ductility. This highlights the beauty and adaptability of medium Mn steels, offering a flexible design pathway for advanced structural applications, indicating a hidden sustainability advantage: processing-driven property tuning minimizes the need for energy- and resource-intensive changes in chemical composition.

Speaker: Vahid Javaheri (University of Oulu)

30 In-situ Investigation of Austenite Decomposition During Prolonged Isothermal Holding of TRIP Steels

Retained austenite provides TRIP (Transformation-Induced Plasticity) steels with their exceptional combination of strength and formability. To retain a sufficient volume fraction of austenite, alloying with silicon (Si) or aluminum (Al) is used to suppress carbide formation during the bainite transformation. This suppression allows the austenite to enrich with carbon, stabilizing it at room temperature.
While Si and Al effectively inhibit carbide precipitation for standard transformation durations (e.g., several minutes), prolonged holding at the isothermal bainite transformation temperature eventually triggers carbide formation within the austenitic regions. These precipitates deplete the carbon concentration in the austenite, destabilizing it and promoting martensite formation upon final quenching. Understanding this decomposition process is critical for optimizing the industrial production of TRIP steels, particularly for large-scale coils where slow cooling rates can result in holding times of several hours, ultimately reducing the TRIP effect.
To investigate this behavior, a steel containing 0.4 wt% C, 1.5 wt% Mn, and 1.5 wt% Si was austenitized at 950 °C and quenched at 50 K/s to bainite transformation temperatures ranging from 350 to 450 °C. Samples were held isothermally for up to 8 hours. To track the microstructural evolution in real-time, in-situ X-ray diffraction (XRD) was performed at DESY (Deutsches Elektronen-Synchrotron). The experimental results are discussed and compared with MatCalc thermodynamic simulations to characterize the kinetics of carbide formation.

Speaker: Philipp Retzl (TU Wien)

31 Thermomechanical processing of Cu- and Mo-containing multiphase steels subjected to Quenching and Partitioning treatment

Multiphase steels, such as medium-Mn and QP steels, are of key interest for automotive industrial applications. The primary characteristic of these steels is strain-induced martensitic transformation (SIMT) of retained austenite (RA) during deformation, enabling substantial energy absorption. This study investigates the effect of thermomechanical processing on the multiphase steels that contain simulated residual elements like Mo and Cu, subjected to Q&P treatment. Three steels were examined: a base composition of 0.17C-4Mn-0.8Al-0.5Si (wt.%), a base with 0.3 wt.% Mo, and a base with a combined 0.3 wt.% Mo and 1.0 wt.% Cu additions. The phase transformation behavior of deformed austenite was characterized by using a high-resolution Bahr DIL805 dilatometer, and the deformation continuous cooling transformation (DCCT) and deformation-temperature-time-transformation (DTTT) diagrams were developed. The evolution of prior austenite grain size (PAGS) was analyzed using different methods (EBSD, chemical etching and thermal etching). As a result, the effect of plastic deformation delays the formation of bainite in all analyzed steels. The Q&P treatments were then designed based on the DCCT and DTTT to identify optimal processing, quenching temperature, and partitioning parameters. Subsequently, selected variants were reproduced using salt bath processing to validate the dilatometric RA stability findings under near-industrial conditions. Mechanical behavior was assessed based on hardness and static tensile tests. The addition of Mo was found to enhance hardenability and delay bainitic transformations. The combined Mo + Cu alloy enhances this effect and optimizes phase fractions and RA stability. The results demonstrate that controlled thermomechanical Q&P processing combined with tailored alloying strategies enable effective tuning of microstructure and mechanical performance in advanced multiphase QP steels.

Acknowledgement
The authors would like to acknowledge Pro-quality program for support in starting scientific activities in new research topics as part of the Excellence Initiative – Research University program, grant no. 32/014/SDU/10-22-001.

Speaker: Mr Firew Kassaye (Silesian University of Technology, Faculty of Mechanical Engineering, Department of Engineering Materials and Biomaterials)

32 Mechanism and Process Control of Intergranular Oxidation in Hot-Rolled Hot-Stamped Steel: Oxygen Supply via FeO Decomposition and Evolution of "Core-Shell Structure" in Grain Boundary Oxides

Intergranular oxidation during the hot-rolling "laminar cooling-coiling-cooling" process critically impacts surface quality and formability of hot-stamped steel. This study investigates 22MnB5 steel through industrial coil sampling and controlled atmosphere simulations (air/vacuum), establishing formation mechanisms and process optimization strategies. Significant positional variations in oxidation depth were quantified: central regions exhibited 15 μm depth versus 0–5 μm at edges, resulting from differential cooling rates and oxygen accessibility post-coiling. Under air atmosphere, oxidation depth followed a characteristic "C-curve" with temperature, peaking at 15 μm near 700°C. Vacuum conditions triggered FeO decomposition, converting protective oxide scales into internal oxygen sources that increased oxidation depth monotonically from 600°C to 900°C (26 μm at peak). Thermo-Calc thermodynamic simulations elucidated FeO decomposition-driven oxygen diffusion and composite oxide-mediated maintenance of localized low-oxygen partial pressure. Transmission electron microscopy revealed oxidation products with distinct "core-shell architecture": preferential SiO₂ nucleation by Si, Cr-enriched shell precipitation, and rapid Mn diffusion filling grain boundary vacancies to form multicomponent oxides.
This study challenges the conventional wisdom that "low-oxygen environments suppress intergranular oxidation", establishing a novel theoretical framework for understanding post-coiling oxidation behavior under internal low-oxygen conditions. Findings directly correlate with industrial quality control metrics. Based on FeO decomposition-driven oxygen supply mechanisms, this work implements low-temperature coiling (<600°C), accelerated front-section cooling, and forced-air post-coiling cooling to effectively controls oxidation depth below 5 μm. This achieves a closed loop from theoretical discovery to engineering application, providing both fundamental principles and actionable guidelines for high-surface-quality hot-stamped steel production with strong industrial scalability.

Speaker: Dr Yang YU (Shougang Group Co., LTD. Research Institute of Technology)

12:10 LUNCH BREAK

Annealing & Softening

33 Effect of Annealing Temperature on Microstructure and Mechanical Properties of High-Mn, High-Al Lightweight Austenitic Steel

In this study, the room temperature tensile and microstructure evolution of a novel cold-rolled lightweight austenitic steel (Fe–19Mn–6Al-4Ni–1C) subjected to different annealing schedules were investigated by transmission and scanning electron microscopy equipped with electron back-scattered diffraction (EBSD) and room temperature tensile test. All experimental samples were furnace annealed under an Ar gas atmosphere at 800°C (S800), 900°C (S900), and 1000°C (S1000) for a holding time of 15 minutes followed by water quench. Microstructural characterization of the processed samples reveals a fully austenitic structure, with the average austenite grain size increasing from 10 µm at 800°C to 30 µm at 1000 °C, respectively. A heterogeneous grain structure obtained at 800°C exhibited an ultrahigh tensile strength of ~1 GPa with an elongation of 45%. The results indicated that multiple deformation mechanisms are involved during the straining of the S800 sample, leading to a simultaneous enhancement of strength and ductility. Increasing the annealing temperature to 1000 °C promoted rapid grain growth, resulting in a significant reduction in tensile strength in S1000 sample.
Keywords: Advanced high-strength steel, Thermomechanical processing, Annealing temperature, Recrystallization, Deformation Twins

Speakers: Mrs Mahsa Barati Mahyari (Materials and Mechanical Engineering, Centre for Advanced Steels Research, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland), Mr Vahid Javaheri (Materials and Mechanical Engineering, Centre for Advanced Steels Research, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland)

34 Thermomechanical processing and continuous annealing of Al-added lightweight steels

In this study, the experimental procedure involved hot rolling (1100°C–850°C) of six novel lightweight steels from different groups: ferritic, ferrite-based and austenite-based, followed by a heat treatment schedule to achieve the desired mechanical properties and compatibility for an industrial continuous annealing line. The heat treatment consisted of soaking at various temperatures between 600 and 1000 °C for 60 s, followed by cooling to the austempering temperature (460 °C) with a holding time of either 3 or 120 s. Microstructural and tensile test characterisation was carried out. Microstructural observation revealed a constituent of a single ferrite, a complex matrix containing austenite, martensite and carbides. Depending on the heat treatments applied, a wide range of mechanical properties was obtained. Generally, in ferritic steels, increasing the annealing temperature does not affect tensile properties; however, in duplex steels, it increases ductility at the expense of tensile strength. For instance, in steel (0.25C-5.7Mn-3.9Al-0.09Nb wt.%), the yield strength (YS) and ultimate tensile strength (UTS) decreased by approximately 300 MPa, while total elongation (TEl) increased from 6.7% to 21.8% as the annealing temperature was raised from 600°C to 1000°C. Isothermal holding at 460°C for an extended period improved strength but reduced ductility in ferritic and austenite-based steels. In ferrite-based steels, mechanical properties largely depend on an annealing temperature, which is attributed to microstructural evolution. Fractography of the tensile specimens revealed various fracture morphologies (brittle, mixed brittle-ductile, and ductile modes) depending on the alloys’ composition and phase constituents. The results indicate that controlled thermomechanical processing is essential for balancing the high-strength requirements of Al-containing lightweight steels.
Acknowledgement: The authors would like to acknowledge Pro-quality program for support in starting scientific activities in new research topics as part of the Excellence Initiative – Research University program, grant no. 32/014/SDU/10-22-002.

Speaker: Mr Tamiru Kori (Silesian University of Technology, Faculty of Mechanical Engineering, Department of Engineering Materials and Biomaterials)

35 Assessing the Role of Retained Austenite Heterogeneity in the Mechanical Properties of Medium-Mn Steels

Medium-Mn steels are promising candidates for next-generation advanced high-strength steels owing to their exceptional strength–ductility balance. The heterogeneity in retained austenite (RA), particularly in terms of chemical composition and morphology, has sometimes been reported to be beneficial. In this study, this view is critically examined to elucidate the effect of austenite heterogeneity on mechanical properties of a 0.4C–6Mn–2Al–1Si–0.05Nb (in wt.%) steel.
The processing was started by intercritical annealing (IA1) of a fully martensitic microstructure to obtain a microstructure approaching the local equilibrium with ~38% RA. 50% cold rolling of this structure led to the partial transformation of RA into strain-induced martensite (SIM). A subsequent flash annealing treatment (IA2), heating at a rate of 100 °C/s up to 780 °C, followed by cooling at a rate of 50 °C/s to room temperature, resulted in the final microstructure consisting of ~58% ferritic phases (ferrite and fresh martensite), and ~42% RA with a mixture of lamellar and blocky morphologies. Additionally, an APT analysis revealed two distinct RA populations in terms of chemical composition: high-Mn RA (deformed RA and reverted SIM) and low-Mn RA (reverted from ferrite), both of them exhibiting reduced C content compared to the RA formed during IA1.
A comparison of tensile properties between IA2- and IA1-treated specimens showed significantly higher work hardening and ultimate tensile strength but a serious 65% reduction in fracture elongation of the IA2 structure. This deterioration in mechanical performance can be attributed to the high fraction of less stable RA and the presence of fresh martensite after IA2, which led to rapid exhaustion of the austenite-to-martensite transformation at an early stage of straining. These results demonstrate that RA heterogeneity is not always advantageous; instead, RA stability plays a pivotal role in mechanical performance.

Speakers: Mr Roohallah Surki Aliabad (University of Oulu), Mr Mahsa Barati Mahyari (University of Oulu), Prof. Vahid Javaheri (University of Oulu)

36 Mechanical Property Comparison of Bainite-Based and Conventional Quenching and Partitioning (BQ&P vs Q&P) in a Medium-Carbon Steel

Advanced high-strength steels are widely used in the automotive industry because of their excellent mechanical properties, which arise from their multiphase microstructure and the transformation-induced plasticity (TRIP) effect. Among advanced heat-treatment routes, quenching and partitioning (Q&P) has been extensively developed to produce retained austenite (RA)-containing microstructures with a favorable balance of strength and ductility. More recently, bainite-based quenching and partitioning (BQ&P) has attracted attention because bainitic ferrite may improve ductility while maintaining high strength. However, direct comparisons between conventional Q&P and BQ&P remain limited, particularly regarding RA fraction and mechanical performance.
In this study, the effects of bainite formation and partitioning temperature on mechanical properties (tensile and fracture toughness) were compared in a 0.4C–1.5Si–2Mn–1Cr–0.3Mo–0.2V (wt.%) steel, beside the microstructural characterization using FESEM-EBSD and TEM microscopies. Heat treatments were performed using a Gleeble thermomechanical simulator. For the Q&P route, a quench-stop temperature (QT) of 150°C was followed by partitioning (PT) at 200°C and 300°C for 1000 s. For the BQ&P route, samples were first held at 300°C for 400 s to allow bainitic transformation before quenching to 150°C, after which the same partitioning conditions were applied.
The results showed that the final RA fraction was similar in both routes. At 200°C partitioning, the RA fraction was 7.0% in Q&P and 7.5% in BQ&P, while at 300°C it increased to 17% in Q&P and 15% in BQ&P. BQ&P exhibited a higher yield strength than Q&P, increasing from 900 MPa to 1025 MPa at TP = 300°C and from 1229 MPa to 1294 MPa at TP = 200°C. However, ultimate tensile strength was slightly lower in BQ&P (1761 MPa) compared with Q&P (1804 MPa). Fracture toughness results showed no meaningful difference between the two routes. Overall, conventional Q&P provided comparable microstructural and mechanical performance with a simpler processing route.

Speaker: Zeynab Aalipour Hafshejani (Materials and Mechanical Engineering, Centre for Advanced Steels Research, University of Oulu, Finland)

TMP strategies, Modelling & Verification

37 Control and through process prediction of plate thermomechanical properties at JSW’s Anjar plate mill

In-line control of plate microstructure to achieve near-net mechanical properties requires a combination of the correct time temperature strain path during rolling and accelerated cooling strategy to control the grain size and final material phases. This paper firstly reviews the process routes available to produce thermo-mechanically control rolled steel products using the combination of rolling and accelerated cooling. Next a description is given of a recent installation of MULPIC plate cooling technology at JSW’s plate mill at Anjar, India. This technology has been integrated into the existing rolling process and is capable of being used in two ways. Firstly, MULPIC can be used for intermediate cooling, which is applied during the hold phase of controlled rolling and is more traditionally performed using air cooling. This hold time is required to allow the plate to finish rolling below the recrystallisation stop temperature. Secondly, final plate cooling can be applied after the last rolling pass to achieve the desired temperature-time cooling path which determines the room temperature phase fractions and transformed grain size distribution.

The paper also describes the off-line system which allows simulations to be performed of both the rolling and cooling processes. The objective of the rolling model is to describe the incoming high temperature microstructure to MULPIC. Predictions of grain size, residual strain and phase fraction are included. The model uses a prediction of the through thickness temperature evolution during rolling to calculate the effects of recrystallisation, grain growth and precipitation. The cooling model uses these inputs to simulate the phase transformations of austenite into a combination of ferrite, pearlite, bainite and martensite. The resultant transformed grain size distribution together with other material properties are then used to predict the final mechanical properties. Results are presented to demonstrate the accuracy of the model against measurements from production.

Speaker: Dr Ian Robinson (Primetals Technologies)

38 Effect of edge masking on strip deformation in rapid cooling section during endless production

This work examines how edge masking and non‑uniform initial temperature profiles influence steel strip deformation during rapid cooling in endless production. The aim is to support industrial optimization of cooling sections by providing reliable data and validated numerical models. Material properties required for thermo‑mechanical simulations were measured experimentally over a wide temperature range. Position and temperature dependent heat transfer coefficients for different nozzle configurations, pressures, and strip orientations were determined using inverse analysis of temperature histories recorded inside heated test plates. These results were used to build a detailed cooling model in COMSOL Multiphysics capable of predicting deformation during cooling. Numerical simulations show that deformation can start very early in the cooling zone if the cooling intensity changes too quickly or if there is a strong difference between upper and bottom cooling. In such cases, the strip can bend or develop plastic strain that later results in permanent shape defects. The study evaluates the effect of various edge masking and uneven initial temperature across the strip width. Even small temperature deviations at the edges lead to noticeable edge waves or buckling after cooling. When the edges are colder, clear and permanent deformations appear. These results highlight that accurate control of the temperature distribution before entering the cooling section is as important as controlling the cooling intensity itself. The outcomes of this work provide guidelines for production-scale optimization. The model helps to understand the causes of strip deformation and supports improvements in strip flatness and overall product quality in endless manufacturing lines.

Speaker: Michal Pohanka (Brno University of Technology)

39 Recrystallization and Texture Evolution of a Hot Rolled Nb Bearing Ferritic Stainless Steel

The control of recrystallization in ferritic stainless steels is critical for tailoring grain size and optimizing toughness, specially for high thickness grades. While the role of niobium (Nb) in delaying recrystallization is well established in austenitic systems, primarily for carbon steels which are usually hot rolled in austenite, its effect in ferritic stainless steels, which can be rolled in high temperature ferrite, is less discussed. In this work, we investigated the influence of Nb additions on the microstructural evolution of two Nb-alloyed high-chromium ferritic stainless steels, rolled in a laboratory-scale mill at temperatures between 800 °C and 1000 °C. Electron Backscatter Diffraction (EBSD) was used to quantify recrystallization, texture development and other microstructure characteristics. Our results confirms the strong effect of the Nb in solid solution (solute drag) on delaying recrystallization for the high Nb-grade. We believe that the strong segregation of Nb atoms to dislocations at elevated temperatures creates a substantial drag force, inhibiting boundary migration, ultimately affecting recrystallization. The project team managed to use these effects to improve the quality of such hot bands, as when subjected to subsequent heat treatment, these deformed microstructures produced finer grain sizes than fully recrystallized hot bands.
These findings underscore the critical role of solute drag in ferritic systems and provide insights for designing thermomechanical processing routes to achieve superior toughness in high thicknesses Nb-bearing ferritic stainless steels

Speaker: Mr Caio de Paula Camargo Pisano (CBMM | Niobium)

40 A Thermo-Mechanical Controlled Processing Method for Producing High-Toughness Steel Jumbo Beams

Abstract
The production of high-toughness jumbo structural sections remains a significant challenge in heavy section mills due to low reduction ratios, heterogeneous microstructure, and inconsistent mechanical properties across thick flange regions. These challenges are particularly critical for offshore grades (JR, J0, J2), which require strict toughness compliance according to standard.

In this work, a thermo-mechanically controlled processing (TMCP) method is developed for the production of high-toughness steel jumbo beams using a direct reduced iron (DRI)-based steelmaking route. The process is applied to beam blank rolling in a heavy section mill, producing universal columns with flange thicknesses up to 77 mm.

An integrated metallurgical model is established to predict and control microstructure evolution during reheating, rolling, and cooling stages. The model incorporates key process parameters including deformation temperature, reduction per pass, strain accumulation, strain rate, and precipitation behavior of microalloying elements (Nb, Ti, V), with particular emphasis on the determination of the non-recrystallization temperature (Tnr).

A two-stage controlled rolling strategy combining recrystallization controlled rolling (RCR) and conventional controlled rolling (CCR) is implemented to achieve effective austenite grain refinement under limited reduction conditions. The model further predicts ferrite grain size as a function of accumulated strain and cooling rate, enabling optimization of final mechanical properties without reliance on intensive cooling systems.

Industrial application demonstrates improved microstructural homogeneity and enhanced toughness performance while maintaining weldability and reducing alloying requirements.

Speaker: Dr Mohamed Shahtout (EmSteel Group)

15:00 COFFEE BREAK

Cooling Effects and Hardenability

41 Soft Quenching / Martensitic Free processing as a metallurgical route to high performance spooled rebar

The Soft Quenching process applied to the Danieli Spooler incorporates a patented controlled cooling technology specifically developed to enhance the production of compact rebar coils.
In conventional spooler-based quenching systems, cooling is performed in a single high intensity stage immediately after the finishing rolling pass. This approach suppresses diffusive austenite transformation, producing a surface martensitic layer that then undergoes air equalization before coil formation. The resulting microstructure, martensitic-bainitic at the surface and ferritic–pearlitic at the core, meets the required strength standards but introduces heterogeneity and potential residual stresses within the coil.
Danieli’s Soft Quenching process overcomes these limitations through a multistage, modulated cooling strategy that completely suppresses martensite formation, a configuration also referred to as a martensitic-free process.
The process ensures an ultra-fine, fully uniform ferritic–pearlitic microstructure across the entire bar cross section, enhancing metallurgical homogeneity, mechanical consistency, dimensional stability, and product repeatability, while also reducing energy consumption and wear in downstream operations.
The real-time digital control, together with Danieli Automation’s big data and AI-driven systems, continuously regulates the cooling process, maintaining stable cooling rates tailored to product specifications and rolling conditions.
Industrial installations, including the most recent one in Germany at the ESF Elbe Stahlwerke Feralpi rolling mill, have demonstrated the capability to produce coils with markedly improved mechanical consistency across diameters ranging from 8 to 25 mm and coil weights of up to 8 tons.

Speaker: Mr Nicola Simaz (Danieli & C)

42 Influence of Cooling Rate and Reaustenitization Strategy on the Mechanical Properties of Ni–Mo Alloyed Quenched and Tempered Thick Plates

The combination of nickel and molybdenum additions is widely used to enhance hardenability and low‑temperature toughness in quenched and tempered thick plates. However, the interaction between alloying content, cooling rate during quenching, and reaustenitization strategy remains critical for achieving uniform martensitic microstructures through the plate thickness. In this work, two low‑carbon Ni–Mo-B alloy designs (0.5% and 1%Ni) were evaluated to quantify the effect of cooling rate and reaustenitization conditions (single quench at 910 °C or 950 °C, and double quench at 910 °C) on tensile and toughness properties.
Plane strain compression tests were used to replicate industrial thermomechanical schedules, followed by controlled quenching and tempering. Tensile testing, Charpy impact testing, and extensive microstructural characterization (OM, FEG‑SEM and EBSD) were performed to relate microstructure to mechanical response.
For both alloys, increasing the cooling rate promoted higher tensile strength, consistent with the progressive suppression of softer transformation products. In the 0.5%Ni-Mo-B steel, low cooling rates (1–2 °C/s) led to mixed microstructures containing ferritic and bainitic regions embedded in martensite, resulting in inferior toughness. In contrast, the 1%Ni-Mo-B grade formed fully martensitic microstructures across all cooling rates, displaying more stable toughness levels and confirming the beneficial role of nickel in improving through‑thickness hardenability. Reaustenitization at 950 °C and the application of a double quenching at 910 °C produced more homogeneous martensite, improving both tensile and toughness performance. The toughness improvement associated with double quenching was particularly pronounced for the 0.5%Ni-Mo-B steel, where mixed microstructures were effectively eliminated.
Overall, the results highlight the combined effectiveness of Mo and Ni alloying, cooling rate, and reaustenitization strategy in controlling microstructural homogeneity and optimizing the strength–toughness balance in heavy‑gauge quenched and tempered Ni–Mo-B steels.

Speaker: Dr Pello Uranga (CEIT-BRTA and University of Navarra-Tecnun)

43 Producing High Strength H-Beams with Thermo-Mechanical Control Process (TMCP): the Danieli QST – Quenching & Self-Tempering process

Heavy beams producers selected Danieli technology to apply Thermo-Mechanical Control Process (TMCP) at their rolling mills.

Thanks to this process, the product portfolio can be expanded with high strength beams in fine-grained structural grades according to the European (EN 10025-4) and American (A913/A913M) standards.

High-strength beams offer substantial savings in construction in terms of material weight and fabrication costs (mainly welding) for a wide range of applications, such as high-rise buildings, long-span bridges, constructions in seismic areas, and offshore structures.

These beams are obtained through TMCP from low-alloy grades chemistry steels that provide excellent weldability (no pre-heating required) while achieving good toughness at low temperatures.

The thermo-mechanical control process is performed by Selective Flange Cooling (SFC) in combination with Quenching & Self-Tempering (QST), treating the entire beam.

The SFC equipment is installed at the entry and exit sides of the reversing finishing mill through cooling side guides, followed by the QST system at the exit side.

Danieli QST-treated beams have been industrially produced over the past ten years. Results demonstrate the QST system’s ability to exceed the most demanding global requirements.

Furthermore, recent tests carried out at the Danieli Research Center demonstrated that a tuned nozzle configuration grants better cooling efficiency and water savings of up to 30% compared to the previous version.

Speaker: Mr Andrea Palma (Danieli & C)

44 Balancing Strength and Ductility in TMCP API X70 Plates: Industrial Control of Yield-to-Tensile Ratio

Abstract

The balance between strength and ductility is a key requirement in pipeline steels, where the yield-to-tensile (Y/T) ratio directly influences strain capacity and resistance to failure under complex loading conditions. In thermo-mechanical controlled processing (TMCP) of API X70 plates, maintaining a low and stable Y/T ratio while meeting strength and toughness requirements presents a critical metallurgical and process challenge.

This study presents an industrial investigation into the control of Y/T ratio in API X70 plates produced in a 4900 mm heavy plate mill. The work examines the combined effects of alloy design, deformation history, and accelerated cooling on the relationship between yield strength and tensile strength.

A coordinated optimization strategy was implemented, including reduced carbon levels, controlled microalloying, and precise Ti/N ratio management to enhance grain refinement while limiting excessive strengthening. Process parameters were refined through controlled rolling and optimized cooling conditions to promote a balanced ferritic–bainitic microstructure and suppress the formation of hard phases that elevate yield strength disproportionately.

Industrial results demonstrate that the optimized approach achieves stable Y/T ratios below 0.85 while maintaining required strength levels and toughness performance. The findings confirm that an appropriate balance between strength and ductility can be consistently achieved through integrated metallurgical and process control.

This work provides a practical framework for engineering strain capacity in TMCP plate production under real industrial conditions.

Speaker: Amin Asiaban (Iron and Steel Affairs, Espadana Industrial Investment Group, Tose’e Farayand San’ati Mehregan – TFSM (Industrial Process Development Company))

TMP strategies, Modelling & Verification

45 Advanced Thermomechanical Processing for High-Strength Pipe Steels

A very fine ferritic structure is important for achieving the required mechanical properties for high-strength pipe steels during hot strip rolling. Pipe steels are usually produced by thermomechanical rolling with low rolling temperatures during finishing. This rolling practice is demanding on capacity and equipment.
To overcome this problem, an advanced rolling strategy for high-strength pipe steels as hot strip was established based on numerical metallurgical modelling of microstructure and mechanical properties. In conjunction with a simultaneous adjustment of the cooling strategy with increased cooling rates, roughing and especially finishing can be carried out more gently.
Therefore, it is possible to achieve at least unchanged product properties with high homogeneity while at the same time increasing rolling performance and protecting the mill stand.
The intended paper will introduce the setup, metallurgical mechanism and modes of operation of the advanced rolling strategy. As an overview the main aim is to show that through consistent usage of Nb and the associated metallurgical mechanism recrystallization and transformation during rolling the novel process leads to an increase in the performance of the hot strip mill compared to classic thermomechanical rolling and that the set microstructure ensures consistent product performance in terms of strength and brittle fracture resistance for high-strength pipe steels in various thicknesses.

Speaker: Prof. Andreas Kern (thyssenkrupp Steel Europe)

46 A novel strategy to achieve uniform fine grains in carburised gear by tailoring the deformation gradient through the forging process

Carburised gears have been widely used in various mechanical transmission engineering fields. However, the carburising process is prone to mixed grain defects constraints on the carburising temperature further increase. Uneven distribution of grain will seriously damage the hardness, impact toughness and fatigue strength of gears and other key mechanical properties. The development of new energy vehicles and other fields of development for warm forging and other precision moulding gear requirements are becoming more and more stringent. Unfortunately, warm forging gears have a higher probability of occurrence of mixed grain. Different from the conventional precipitated particles regulation, we propose a new method for the design of precision-formed gear blanks based on the optimisation of deformation parameters. Firstly, we constructed the heat deformation constitutive equations applicable to the complete austenite and dynamic ferrite zones. Elucidated the dynamic changes of the grains under the warm forging condition. Secondly, by changing the shape of the billet, we accurately tailored the deformation gradient to achieve the reasonable optimization of the warm forging process. Lastly, by combining the finite element simulation with the industrial trial, we analyzed the grain evolution law of the whole process. It realized that the final gear finished product had an extreme difference in the grain size within 1.5 levels.

Speaker: wanli sun (University of Science and Technology Beijing)

47 Inline laser ultrasonics for microstructure verification of heat treatments and thermal processes (ILUMHEAT)

Using laser ultrasonic (LUS) measurements, the microstructure of metal can be determined directly in situ. The measurement is non-contact and nondestructive, meaning it can be used for hot and moving samples, meaning microstructure can be determined in many parts of the steelmaking process where other techniques are not viable. The feasibility of inline LUS grain size measurements [1] as well as the utility of the captured data [2] have been demonstrated by an installed LUS instrument at the SSAB Borlänge hot strip mill.
In the ILUMHEAT project, funded by Vinnova as part of the “Swedish Metals & Minerals” program, we aim to bring a new LUS grain size gauge and microstructure probe to four Swedish steel mills. For each site, there are unique questions about the grain size and microstructure evolution, as well as unique challenges regarding the installation and use of the LUS probe. A modular design with a working distance of 1 meter has been developed as part of this project, and the preliminary results of the first on-site measurement will hopefully be presented.

[1] Malmström M, Jansson A, Hutchinson B, Lönnqvist J, Gillgren L, Bäcke L, et al. Laser-Ultrasound-Based Grain Size Gauge for the Hot Strip Mill. Applied Sciences 2022;12:10048. https://doi.org/10.3390/app121910048.
[2] Hoppe D, Haschke T, Sprock A, Hassel C, Hafer J, Bäcke L, Thorberg J-E, Jonsson C, Malmström M, Kneisel F, Bärwald M, New insights into the online LUS grain size measurements, in: Associazione Italiana di Metallurgia, Verona, 2025: pp. 227–234.

Speaker: Hampus Wikmark Kreuger (Swerim AB)

48 The Effect of the Rolling Strategy on the Low-Temperature Toughness and Microstructure of Heavy Plate Material

Within the present investigation, instrumented drop-weight tear tests were carried out on industrially produced heavy plate material that was thermomechanically rolled using two different strategies. In one case, the material was air-cooled from the final rolling temperature and in the other case it underwent accelerated cooling from above the austenite to ferrite transformation. Both rolling strategies were fine-tuned to result in a similar strength level. However, the strategies had a significant effect on the resulting microstructure of the plate material. Air cooling from the final rolling temperature in the ferrite regime resulted in a predominantly ferritic-pearlitic microstructure, while accelerated cooling from above the Ar3-temperature led to a predominantly bainitic microstructure. The microstructure was investigated by light-optical microscopy as well as electron microscopy in combination with electron backscatter diffraction. The relationship between the processing strategy, microstructure and the low-temperature toughness is discussed in light of previous experiences.

Speaker: Dr Charles Stallybrass (Salzgitter Mannesmann Forschung GmbH)

49 Optimized pass schedule design to influence the mechanical properties of hot rolled strips

Austenite grain size is an important parameter for controlling the mechanical properties of microalloyed steels during hot strip rolling. With the installation of a laser-ultrasonic (LUS) measurement gauge at SSAB’s hot strip mill in Borlänge, a sensitive, non-contact inline method is available that allows the grain structure to be measured immediately after the final finishing stand.
This paper focuses on the development and use of the Pass Schedule Calculation (PSC®) model to describe and influence austenite grain size by optimized pass schedules. The process model PSC® represents, amongst other things, the thermo-mechanical conditions during rolling including temperature evolution, deformation distribution, recrystallization, precipitation and grain growth/refinement. In recent years, the model performance has been steadily improved by means of comparison with a large set of LUS measurements.
With the model thus improved, targeted optimizations of the pass schedule are now possible to specifically influence the mechanical properties of the final product. It was found that, for example, the adjustment of the transfer bar thickness has a significant impact. By increasing the transfer bar thickness, the accumulated deformation in the finishing mill increases, which tends to promote a more uniform recrystallization and a more homogeneous austenite grain size distribution along the strip length. The comparison between PSC®-predicted austenite grain size and LUS measurements shows that the model can reproduce the measured trends reasonably well.
The more uniform grain structure also influences downstream processes, especially cold rolling, where yield strength scatter is reduced. Overall, the results suggest that LUS measurements can be used as feedback information for PSC®-based pass schedule optimization.
In the future, combining PSC® and LUS measurements could further support microstructure-based pass schedule control in hot strip mills – for example to support grain refinement and reduce property variations.

Speaker: Dr Thomas Haschke (SMS group GmbH)

17:30 Departure by bus - CONFERENCE DINNER

Buschenschank Fuhrgassl-Huber

Thursday 22 October

Plenary Talk(s)

50 Impact of preheating and hot rolling on AA6016 sheet texture and formability

EN-AW-6016 sheet material is highly demanded for automotive applications due to its balanced properties of formability, strength, and corrosion resistance. Formability is characterized by the anisotropy of the sheet (r-value) and the ability to allow flat hems without surface cracks. The thermal history of the hot band, including ingot preheating and hot rolling, is crucial for the final properties. Alloy 6016 contains high levels of Si,leading to pure Si precipitates alongside Mg2Si. Ingot preheating temperature affects the amount of Si and Mg in solid solution, while the hot rolling cooling rate influences the size of Si and Mg2Si precipitates. Coarse particles can enhance particlestimulated nucleation (PSN), reducing Cube texture. Reduced Cube texture benefits lower planar anisotropy (Δr) for deep drawing but can be detrimental for hemming.

Three hot bands with varying sizes of Si and Mg2Si precipitates were produced by AMAG. Despite similar production steps after hot rolling, the final sheet material showed equal strengthand elongation, but differences in r-value and hemming behavior due to texture variations. Effective hemming is essential in the production of automotive doors and closures to prevent surface cracks and ensure the aesthetic quality of the components.

Speaker: Dr Josef Berneder (AMAG rolling GmbH)

Computation and Modelling, ML and AI

51 Validation and optimization of a recrystallization model to enhance the accuracy of microstructure evolution predictions in heavy‑plate rolling

The microstructure of austenite developed during plate rolling is significant for the final microstructure and therefore for the mechanical properties of heavy plates. Accurate prediction of the grain size, including its homogeneity and distribution, at each pass is essential for optimizing the rolling schedule. Especially in the production of heavy plates rolled from very thick slabs or plates with large widths, rolling passes with very low deformations cannot be avoided. In those passes, the microstructure can only partially recrystallize, which may result in an inhomogeneous grain size distribution.
The recrystallization kinetics of different alloying systems, with and without microalloying elements, were investigated in detail by performing uniaxial compression tests on a Gleeble 3800. In these tests, a wide range of deformation parameters, such as strain, interpass time, and temperature, were systematically varied. In particular, understanding the evolution of the microstructure during the recrystallization is important. For this purpose, samples deformed to different strain levels were quenched at various times during the recrystallization process, and the austenitic microstructure was revealed by etching.
These results were used to optimize the recrystallization model, which is implemented in the rolling simulation tools, to reliably simulate recrystallization and the evolution of austenite grains at the pass level. Special attention was given to ensure that the model can predict the inhomogeneous grain size distribution evolving from partial recrystallization and not only the correct average grain size. To validate the model, various rolling schedules were simulated, and the predicted final microstructures were compared with those of the rolled plates.

Speaker: Maita Roberts-Zimmer (AG der Dillinger Hüttenwerke)

52 Hydrogen embrittlement resistant carbon/stainless multilayer steel produced by thermomechanical processing

The demand for hydrogen resistant materials is increasing due to planned usage of hydrogen as energy according to European Union’s AFIR – Alternative Fuels Infrastructure Regulation. The infrastructure needed for storing and transporting hydrogen requires vast amounts of materials withstanding embrittlement and other failures caused by hydrogen. Austenitic stainless steels with their face-centered cubic (FCC) crystal structure are known for their excellent resistance against hydrogen embrittlement. However, stainless steels generally have moderate strength, and their extensive usage is relatively expensive. Carbon steels would offer cost-friendly solution with improved strength, but their body-centered cubic (BCC) crystal structure is prone for hydrogen embrittlement.
The beneficial properties of the two steels can be potentially combined by joining them together by hot-rolling. The thermomechanical process to produce reliably bonded multilayer steel was developed in our study. The microstructure of the interface region was studied using up-to-date characterization methods. The steel was charged with hydrogen, and the mechanical properties were tested by tensile testing with and without hydrogen. A multi-physics numerical model using phase field method to predict hydrogen embrittlement was developed and validated against the experimental results.
The results showed that the stainless steel, specifically AISI 316L, layer acted as a diffusion barrier protecting the carbon steel and provided improved toughness and excellent resistance against hydrogen embrittlement, whereas carbon steel layer provided increased strength making the developed multilayer steel a potential candidate as a material needed for hydrogen-carrying infrastructure.

Speaker: Henri Tervo (University of Oulu)

53 Use of mesoscale models in designing thermomechanical processes for light alloys

Industrial thermomechanical treatments of metallic components consist of several steps of plastic deformation, either followed or alternated with heat treatments. The workpiece, regardless of its initial shape and microstructure, undergoes heterogeneous plastic deformation and temperature distribution during thermal and forming processes. These conditions drive microstructural changes such as strengthening, recovery, recrystallisation, allotropic phase transformation, and phase globularisation. Over recent years, we have developed a mean-field model that predicts microstructural changes and mechanical behaviour during thermomechanical processing and heat treatments. The model accounts for alloy diversity and microstructure evolution in workpieces under non-isothermal, non-isochronous conditions. Our approach incorporates time continuity, showing that properties and microstructure depend on both state variables and the processing path. When integrated into finite element simulations, the model can handle complex shapes with varying temperatures and deformations, predicting heterogeneous microstructural evolution driven by local thermomechanical histories—including temperature, strain, and strain rate. In this work, we introduce a lower-cost computational solution for processing design using physically informed processing maps. These maps enable us to determine microstructures and mechanical responses, thereby helping identify optimal processing conditions for specific local scenarios. For this study, we use examples of near-beta titanium alloys (Ti-Mo and Ti17) and 6082 aluminium alloy, validating the results through compression tests on a Gleeble® 3800 across a wide range of deformation and annealing conditions to obtain the mechanical response. Microstructural information is obtained using scanning electron microscopy and electron backscatter diffraction. The maps can depict both isothermal and non-isothermal conditions; strain rate and temperature rate profiles can be nonlinear; and variations in the initial microstructure are accounted for.

Speaker: Maria Cecilia Poletti (IMAT Graz University of Technology)

54 Multiscale characterization methodology combining experimental and AI-based methods for the study of austenite conditioning in Nb-HSLA steels.

Thermomechanical processing (TMP) of high-strength low-alloy (HSLA) steels relies on the careful control of the interaction between recrystallization and strain-induced precipitation during austenite conditioning. A comprehensive understanding of this interaction requires the simultaneous quantification of prior austenite grain size evolution and niobium carbonitride precipitation across a wide range of deformation conditions. These tasks remain experimentally challenging due to the statistical significance required and the multiple length scales involved.
In this work, we propose a characterization methodology combining experimental and AI-based methods for the systematic study of the correlation between grain size, recrystallization, and strain-induced precipitation in a Nb-bearing HSLA steel (0.04 wt.% Nb). Double-hit compression tests were performed in a Gleeble simulator at 975 °C with strains ranging from 0.15 to 0.4 and interpass times from 5 to 4000 s, covering the full range of recrystallization kinetics including the characteristic stasis plateaus.
The methodology integrates three complementary approaches: (i) a deep-learning-based semantic segmentation model for the automated reconstruction of prior austenite grain boundaries on light optical micrographs, enabling statistically significant grain size distributions over large areas; (ii) a machine-learning model for the segmentation of Nb(C,N) precipitates in STEM images on carbon extraction replicas, overcoming the limitations of conventional thresholding in the presence of microstructural relief; and (iii) matrix dissolution combined with ICP-OES analysis, used to normalize the volume fraction derived from extraction replicas and to correct the overestimation inherent to Ashby's equation. A filtering strategy is additionally proposed to exclude copper sulfides from the precipitation quantification.
This approach reveals a continuous evolution of grain size and precipitate size distribution during recrystallization stasis, challenging the assumption of constant grain size in existing models and establishing a basis for the systematic study of microstructure evolution during TMP.

Speaker: Dr Jenifer Barrirero (Materials Engineering Center Saarland -MECS)

Non-Ferrous Alloys (AI, Cu, Mg and Ti)

55 Tailoring thermal expansion of Titanium alloys by thermomechanical processing

Operation conditions in microelectronics, sustainable mobility, and space exploration increasingly demand mastering thermal expansion due to large temperature swings and stringent dimensional tolerances. However, customizing thermal expansion of conventional metallic materials is extremely difficult. Their expansion behaviour is largely unaffected by alloying, and their lattice expansion typically shows minimal or no crystallographic anisotropy, limiting the usefulness of texture engineering. Even Fe–Ni Invar alloys, despite their widespread use, offer only a narrow window of low yet still positive expansion coefficients. While some materials with negative thermal expansion are known, they are predominantly non-metallic, often brittle, and difficult to texture.
Recently, several research groups have introduced a new materials design principle that enables broad tailoring of thermal expansion in a large class of alloys through straightforward thermomechanical processing. The key feature shared by these materials are martensitic phases with strongly anisotropic lattice expansion. For a single alloy chemistry, the macroscopic polycrystal thermal expansion can be adjusted across a wide range by generating crystallographic texture via appropriate deformation routes. Among such systems, Ti alloys forming orthorhombic α'' phases stand out due to their exceptionally large contraction and expansion rates, excellent deformability, and strong composition-dependent expansion behaviour.
This presentation will review foundational findings and recent advances from the past two decades and provide an overview of current research directions. A new integrated strategy developed by our group—combining control of phase constitution, texture, and phase fraction—significantly enlarges the available design space, offering ample prospects for future exploration and technological innovation.

Speaker: Matthias Bönisch (KU Leuven)

56 Modeling of the production process of a UDIMET720LI turbine disc using a multi-class grain size model and a multi-scale mean-field approach

Due to increasing operating temperatures in low-pressure turbine discs of next-generation geared turbofan engines, materials with superior high-temperature capabilities beyond those of alloy 718 are necessary. Among the promising candidates, UDIMET720LI offers excellent mechanical and environmental resistance properties; however, its narrow processing window poses significant challenges during industrial manufacturing. To reduce the need for costly thermomechanical treatments such as isothermal forging while still ensuring specification-compliant microstructures and mechanical properties throughout the component, robust process design strategies are essential. To address these challenges, a finite element method (FEM) coupled multi-class grain size model, originally developed for alloy 718, has been further adapted and extended for UDIMET720LI. The multi-class approach enables the prediction of heterogeneous grain size distributions arising from billet inhomogeneities and incomplete recrystallization processes. Furthermore, a thermo-kinetic mean-field model capable of accurately describing the γ′ precipitate evolution has been integrated to improve the prediction of local microstructures and resulting mechanical properties. The models were parameterized using extensive laboratory-scale compression experiments covering a broad range of temperatures, strain rates. To validate the developed framework and process design methodology, prototype forgings with varying process parameters were manufactured on industrial-scale equipment and characterized through certified testing laboratories, including microstructural analysis and mechanical property evaluation. The results demonstrate very good agreement between simulations and experiments, confirming the high predictive capability of the coupled modeling approach. The developed framework therefore represents a powerful tool for the robust and efficient design of future UDIMET720LI turbine disc manufacturing processes.

Speaker: Drazen Brescakovic (Materials Center Leoben Forschung GmbH)

57 Microstructure and mechanical properties evolution during thermomechanical processing of INCOLOY 925 alloy

INCOLOY 925 is a high-performance nickel-based alloy widely used in industrial applications where both high strength and excellent corrosion resistance at elevated temperatures are mandatory. This study investigates the hot deformation by forging and, heat treatment by solution annealing and ageing behaviour of INCOLOY 925 alloy. The hot deformation by forging was performed in two stages, first stage at 1075°C with an applied deformation degree of 60% followed by a second deformation stage at 975°C with an applied deformation degree of 25%. The heat treatment processing was performed after hot deformation and comprised of two stages, a solution annealing, at 1010°C with a soaking duration of 1h and air quenching, followed by a double ageing treatment, at 740°C with a soaking duration of 8h followed by a soaking at 620°C with a duration of 17h. The microstructural evolution during thermomechanical processing was performed using XRD and SEM-EBSD investigation techniques, while the mechanical behaviour was investigated using tensile testing. Data referring to microstructural constituents, grain size (D) and mechanical properties was obtained and analysed. In all processed stages the microstructure consists of γ-phase, γ’-phase and MC (M: Cr, Mo, …) carbides. Comparing the mechanical properties obtained during different thermomechanical processing stages showed that the solution annealing favours ductility properties (i.e. elongation to fracture) in comparison with the hot-deformation, while the ageing treatment favours strength properties (i.e. ultimate tensile strength, yield strength) in comparison with the hot-deformation and the solution annealing.

Acknowledgements. This work was supported by a grant from the Ministry of Research, Innovation and Digitization (Romania), CCCDI—UEFISCDI, project number PN-IV-P7-7.1-PTE-2024-0364, within PNCDI IV.

Speaker: Prof. Vasile Danut Cojocaru (National University of Science and Technology POLITEHNICA Bucharest)

58 Enhanced Mechanical and Electrical Properties of Cu-Based Alloys via TMCP Techniques

Copper-based alloys are widely used in advanced electrical, thermal, and structural applications because of their excellent electrical conductivity, thermal transport, and corrosion resistance. However, their industrial applications are often limited by the traditional trade-off between mechanical strength and electrical conductivity, in which conventional strengthening methods may reduce electron transport efficiency. Thermo-Mechanically Controlled Processing (TMCP) has emerged as an effective strategy to overcome this limitation by controlling the integration of deformation and heat-treatment processes to optimize alloy microstructure and properties.
The present article provides a comprehensive overview of recent advances in TMCP of Cu-based alloys, with particular emphasis on Cu-Al, Cu-Cr-Zr, Cu-Ni-Si, Cu-Fe-P, and Cu-Ti systems. The influence of key processing parameters, including deformation temperature, strain level, strain rate, rolling schedule, aging treatment, and cooling conditions, on microstructural evolution is critically discussed. Special attention is given to recrystallization behavior, precipitation kinetics, grain refinement, dislocation substructures, and texture development, as well as their effects on strength and electrical conductivity.
The discussion highlights the important roles of nanoscale precipitates and ultrafine-grained microstructures in achieving simultaneous enhancement of tensile strength, hardness, wear resistance, and conductivity. Recent experimental findings, physically based models, and thermodynamic-kinetic simulation approaches are analyzed to clarify the relationships among processing, microstructure, and properties. In addition, the growing importance of Gleeble-based physical simulation and advanced characterization techniques for optimizing TMCP routes and predicting alloy performance is discussed.
The findings demonstrate that optimized TMCP schedules can produce Cu-based alloys with tensile strengths exceeding 700 MPa while maintaining conductivity levels of 70–90% IACS. Such performance makes these alloys highly attractive for applications in power generation, electrical connectors, resistance welding electrodes, transportation, and advanced electronic systems.

Speaker: Eman El-Shenawy (Central Metallurgical R&D Institute (CMRDI))

10:20 COFFEE BREAK

Computation and Modelling, ML and AI

59 Simulation of Thermomechanical Processing in the Light of Green Steel Transformation

The transition toward circular steel processing, driven by increased recycling and low-CO₂ production routes, introduces new challenges for the thermomechanical processing (TMP) of steels. Higher scrap utilization leads to greater compositional variability, influencing phase transformations, recrystallization kinetics, and precipitation behavior, and consequently affecting mechanical properties.
To maintain optimal performance under these conditions, TMP routes must be adapted through optimized processing parameters and robust alloy design strategies. In this context, material simulation plays a crucial role by enabling the prediction of microstructural evolution and property development under varying compositions and processing conditions. Approaches such as thermodynamic and kinetic modeling support process optimization and help reduce experimental effort.
Overall, this work demonstrates how advanced material simulation can be effectively applied to address these challenges and to support the development of robust and sustainable steel processing routes.

Speaker: Daniel Marian Ogris (voestalpine Forschungsservicegesellschaft Donawitz GmbH)

60 Microstructure Modeling for Thermomechanical Processing of age hardenable aluminum alloys

Designing thermomechanical processing routes requires accurate control of microstructure evolution across sequential deformation and heat-treatment steps. In this work, we present a physics-based model that continuously predicts the microstructural evolution of AA6082 throughout complex thermomechanical histories. A key feature of the model is its ability to carry forward the microstructure from one processing step to the next, such that the state after deformation serves as the initial condition for subsequent processing, such as heat treatments.

We describe microstructure evolution during plastic deformation using a continuous dynamic recrystallization framework that tracks dislocation density, grain and subgrain sizes, boundary misorientation distributions, and grain boundary fractions. We couple these internal variables with constitutive equations to predict flow stress as a function of strain, strain rate, and temperature. After deformation, the stored energy coming from dislocation accumulation drives restoration processes during the subsequent heat treatment.

To validate the model, we performed compression tests on cylindrical samples at temperatures between 25 °C and 450 °C, strain rates from 0.1 s⁻¹ to 1900 s⁻¹, and varying strains. We then applied controlled heating to the solution heat treatment temperature at rates between 1 and 20 K/min. We characterized the resulting microstructures using EBSD and used both flow curves and microstructural data to calibrate the model.

The model captures key features of the material response, including strong initial strain hardening due to dislocation pileups and the subsequent evolution during restoration. We show that the recrystallization occurs already during heating, and that the start temperature increases with heating rate, while remaining largely insensitive to deformation rate for the lower deformation temperatures. The results highlight the competing roles of recovery in the static recrystallization and demonstrate the capability of the model to predict microstructure evolution continuously across thermomechanical processing steps.

Speaker: Talina Terrazas Monje (TU Graz)

61 Constitutive flow behaviour and processing maps of 1CrMoV bainitic steel used in turbine applications

This study aims to understand the hot deformation behaviour of 1CrMoV bainitic steel, produced industrially using hot forging route and is extensively used in turbine applications in power plants. Hot isothermal compression tests were carried out in the temperature and strain rate ranges of 800 - 1150 °C and 0.001 – 30/s, respectively, typical of hot working range using a Gleeble 3800 thermomechanical simulator to characterize the constitutive flow behaviour. Constitutive equations based on the hyperbolic-sinusoidal Arrhenius-type model were developed to define the hot deformation characteristics of the steel. The hot workability of the steel was characterized by developing processing maps based on the principles of dynamic materials model (DMM). This paper presents a processing map developed for a specific strain of 0.6 over the temperature and strain rate ranges specified above, describing the isoefficiency contours of power dissipation (η) superimposed with instability parameter (ξ) values plotted in the strain rate - temperature space, thus delineating clearly various deterministic domains and cracking /instability regimes. Deformation mechanisms specific of these domains and regimes were identified based on the efficiency values and further confirmation through microstructural characterization. A domain occurring at 1100 °C/ 0.1/s extending over the temperature and strain rate ranges of 1050 – 1150 °C and 0.01-0.6/s, respectively, has been identified to be a high efficiency domain with widely spaced isoefficiency contours. In general, dynamic recrystallization (DRX) is likely to occur in such a domain, which is also considered to be a safe processing route resulting in microstructural reconstitution and this has been verified by microstructural examination. Similarly, other domains and regimes identified based on their characteristic efficiencies and shapes were validated by microstructural characterization. The outcomes of this study provide a practical guidance for optimizing forging schedules and improving the processing robustness of turbine grade steels such as 1CrMoV.

Speaker: Rishabh Bharadwaj (University of Oulu)

62 Effect of Roller Misalignment on Thermo-Mechanical Stress in the Secondary Cooling Zone of a Twin-Slab Caster

This study investigates the stress and strain evolution in slabs in a twin-slab caster, with focus on the effect of roller misalignment. A finite element model (FEM) was used to simulate a small section of the slab as it passes through the secondary cooling zone. The model accounts for thermal gradients and mechanical interactions with supporting rollers. The results show that roller misalignment increases the strain level in the slab. The induced deformation propagates downstream along the casting direction and leads to a cumulative effect. Even small misalignments can influence the stress–strain evolution beyond their local region. Based on the findings, guidelines are proposed to reduce the impact of roller misalignment and improve slab quality.

Speaker: Prof. Chenn Zhou (Purdue University Northwest)

Effects of Tramp Elements

63 Influence of tramp elements on static recrystallization after hot deformation of a Nb-micro-alloyed steel

The use of an electric arc furnace (EAF) can significantly lower CO2 emissions during the steelmaking process compared to the conventional blast furnace route. Depending on the quality of the scrap metal, elements such as chromium, molybdenum, and tin can end up in the steel production process.
These tramp elements are difficult or impossible to remove through metallurgical processing. Furthermore, these elements impact the thermomechanical processing and the associated recrystallization behavior of the austenite after hot working. To ensure the right processing parameters, it is important know the effects of these tramp elements and if necessary to adjust the process accordingly. This work investigates the influence of the tramp elements Cr, Mo and Sn on the static recrystallization behavior of the austenitic phase after the deformation step.
The base material was a micro-alloyed steel with 0.08 wt.-% C, 0.9 wt.-% Mn and 0.04 wt.-% Nb and tramp element content of 0.5 wt.-% Cr, 0.15 wt.-% Mo and 0.05 wt.-% Sn were added to the base respectively.
For the experiments, the pocket-jaw unit of the Gleeble 3800-GTC was used to obtain stress-strain curves at different temperatures and interpass times in double-hit-compression-tests. Using the flow stress data, the recrystallized fractions during the interpass times were calculated. Additionally, laser ultrasonic measurements were applied to measure grain growth during heating and the static recrystallization behavior after hot deformation. Furthermore, thermokinetic simulations via MatCalc© were performed to correlate the precipitation kinetics of Niobium carbonitrides with the recrystallization behavior of the austenitic phase.
The results show that at higher temperatures, tramp elements do not affect the recrystallization kinetics. Chromium shows an accelerated recrystallization behavior at lower temperatures, while Tin shows no effect at all investigated temperatures. The results of the double-hit-compression-tests show similar results regarding static recrystallization behavior as the laser ultrasonic measurement.

Speaker: Paul Gawes (University of Applied Sciences Upper Austria)

64 Hydrogen embrittlement and diffusion modelling in QP1180 AHSS for automotive applications

Multiphase steels combine the strengths of different microstructural components, offering both mechanical strength and ductility for lighter designs and lower vehicle emissions. Quenching and Partitioning (QP) steels are a 3rd generation Advanced High-Strength Steel (AHSS) used in vehicles, featuring low-carbon martensite and retained austenite for an excellent strength-ductility balance. It poses significant questions that currently limit its adoption in the automotive industry, primarily to their inherent vulnerability to Hydrogen Embrittlement (HE) and delayed fracture.

In this study, the interaction between hydrogen and QP1180 AHSS was examined. Hydrogen diffusivity and trap energies were evaluated using Devanathan-Stachurski permeation and Thermal Programmed Desorption (TPD) tests on both commercial and pre-deformed QP1180 samples. Additionally, Slow Strain Rate Tensile tests (SSRT) were conducted on electrochemically hydrogen-charged smooth specimens, with the effective hydrogen content measured via the hot extraction method for each specimen. Metallographic analyses and micro-hardness tests were performed to characterize the material microstructure and quantify retained austenite content.
Fractographic examinations using scanning electron microscopy revealed the influence of hydrogen on fracture behavior, showing a transition from ductile to predominantly brittle fracture modes at elevated hydrogen concentrations, with the transition threshold varying based on the specimen orientation with respect to the sheet rolling direction.

Speaker: Giuseppe Macoretta (University of Pisa, Department of Civil and Industrial Engineering)

65 A look under the scale: Cu-alloyed steels during continuous casting, re-heating and hot working

The European steel industry is on the brink of a transformation. With the widespread replacement of the blast furnace iron making route and the use of steel scrap as a raw material, we can expect a higher amount of tramp elements such as Cu, Ni, Mo and Sn in our steels. These steels bring potential for cost-effective alloy design, but also challenges with regards to casting and hot working, with the main concern being selective oxidation and hot shortness due to the presence of Cu. To test the potential of maximum scrap utilization, steels with an increased Cu-concentration and with different levels of Ni were tested. Gleeble tests and heat treatment tests were used to simulate the conditions during continuous casting and hot working, to assess the risk of hot shortness, and to investigate the influence on the microstructure and properties. It was found that Ni- and Cu-rich grain boundary phases accumulate underneath the scale layer, that no negative impact on hot working was present and that elevated amounts of Cu had a slight effect on promoting non-equilibrium phase transformations.

Speaker: Stefan Zeisl (voestalpine Stahl Donawitz GmbH)

66 Influence of tramp elements on thermomechanical processing and properties of martensitic steel grades

Scrap-based steel production is continuously increasing, replacing part of the ore-based steelmaking that is currently the dominant production method for low-alloyed steel grades. Driven by the green transition, scrap-based production using the electric arc furnace (EAF) can significantly reduce CO₂ emissions compared to carbon-based reduction of metal ore. Most emissions in the EAF route originate from electricity consumption, making it particularly suitable for regions with predominantly fossil-free electricity generation.
Scrap-based steelmaking introduces impurities such as copper, tin, and other elements, which can influence steel properties. These effects can often be mitigated through process optimization or alloying adjustments. To increase the acceptance of such trace elements in steel production, and to improve circularity by reducing the need for dilution with high-purity iron sources, it is important to clarify the relationship between impurities and steel properties.
In this study, martensitic low-alloyed steel is investigated with systematic additions of copper and tin. The influence of these impurities on mechanical properties is evaluated. Processing behavior is studied by monitoring the in-situ structure and properties of the austenite phase during thermomechanical processing, using laser ultrasonics coupled with a Gleeble simulator. Complementary hardenability analysis using dilatometry and EBSD characterization is also performed.

Speaker: Dr Hans Magnusson (Swerim AB)

67 Influence of tramp elements on phase transformations, structure, and properties of scrap-based steels.

This contribution combines recent experimental results with literature data to summarize the current understanding of how tramp elements, introduced through the increased use of scrap in steelmaking, affect processability, microstructure, and the resulting mechanical properties of steels. Tramp elements such as Cr, Ni, Sn, Sb, Cu can give rise to a wide range of potential effects, including retardation of diffusion-based phase transformations, incomplete recrystallization, grain refinement, precipitation, grain boundary segregation, or shift of ductile-brittle transition temperature. The main impacts on material performance include strengthening, loss of ductility, and various forms of embrittlement. The likelihood and magnitude of these effects depend strongly on the concentration of tramp elements, the applied heat treatment, and the chemical composition of the steel. Building on the fundamental understanding of how tramp elements influence structure-property relationships, potential mitigation strategies aimed at limiting or counteracting their adverse effects are identified and discussed. Based on the provided results and discussions, it can be stated that in-depth understanding of the impacts of tramp elements combined with tailored counter-measures can support higher scrap utilization rates in circular economy.

Speaker: Oleksandr Glushko (Montanuniversität Leoben)

12:30 CLOSING

12:40 LUNCH - END OF CONFERENCE