5th International High Manganese Steel Conference - HMNS 2022

After a short introduction of voestalpine, the first part of this contribution will give a brief overview of high manganese steels produced and developed by voestalpine group and of cold formable steels for the automotive industry with a special focus towards the 3-GEN advanced high strength steels (AHSS). Regarding cold rolled strip steels, the relationship between global and local...

Medium Manganese Steels (MMnS) belong to the third-generation advanced high strength steels (3.G. AHSS) that have been developed because of their ecological and economic potential with a focus on automotive applications. Reducing weight, decreasing CO2 emission, simplifying processing are important drivers for their development.
This presentation deals with the interaction of chemical...

Influence of nitrogen and carbon on mechanical properties of TWIP steels depending on grain size has been controversially discussed. In addition, especially in high manganese steels, the temperature dependence of the stacking fault energy can lead to the activation or suppression of different deformation mechanisms during a pre-deformation. In this way, a complex interaction between...

Multiphase medium Manganese TRIP steels offer good combinations of high strength and high ductility and can be designed to be used in automotive industry for light weighting purposes. However, the deformation-driven martensitic transformation associated with the TRIP effect strongly deteriorates the materials’ resistance against hydrogen embrittlement (HE). We studied the hydrogen related...

Recently, the new designing concepts for medium-Mn steel have been promoted such as micro-alloyed steels to improve mechanical properties. Several authors reported that micro-alloying was effective to enhance the strength and toughness of medium-Mn steels. In this study, we elucidated the unknown role of micro-alloying element addition to a medium-Mn steel and explored why a micro-alloyed...

Hydrogen embrittlement of high strength steel is one of the critical issue when attempting to prolong the material life for a practical use. Because of this reason, macro/microstructural design for a prevention of hydrogen invasion is important to enhance hydrogen embrittlement resistance of materials. In is study, ultrasonic nanocrystalline surface modification (UNSM) treatment at elevated...

Hadfield steel shows high strain hardening which can be linked to its ability to form twins during mechanical loading. Twinning in Hadfield steel is well documented. However, detwinning in Hadfield steel is only barely investigated but might be an essential effect as during cyclic loading detwinning provides an additional contribution to plastic deformation.
In order to gain more information...

With an increasing demand for high-strength steel with lean-alloyed composition, the medium-Mn steels containing ~3-12 wt.% Mn and ~0.05-0.4 wt.% C have garnered significant attention as next-generation advanced high-strength steels. The α′ martensite microstructure could be observed after hot and cold rolling of the corresponding steel, and it turns to the two-phase microstructure of α...

The strength of ausformed martensite is higher than that of as-quenched martensite. This is believed to be because the dislocation introduced by ausforming is inherited after quenching, and the dislocation density of ausformed martensite is higher than that of as-quenched martensite. However, there is little studies about the detailed relationship between the mechanical properties and...

The global formability of sheet materials corresponds to the ability to undergo uniform plastic deformation without the formation of a localized neck, whereas the local formability addresses the ability to undergo plastic deformation in a local area without fracture. Both the local and the global formability are therefore important properties that can become limiting factors for the...

In order to reduce the vehicles weight constructors are focusing on stronger or lighter materials.
High Mn lightweight steels could be a response to both demands due to high mechanical properties (Yield Strength up to almost 1000 MPa) and low density (15% lower than a standard Hadfield steel and 16% lower than a typical stainless austenitic steel like AISI 306L).
Lightweight steels undergo...

The aim of the presentation is the explanation and description of structural phenomena occurring in high manganese steels with TWIP effect during dynamic deformation, taking into account the heat generated during the deformation and structure changes depending on the stacking- fault energy (SFE) affected by chemical composition. It has been assumed that the ability to activate specific...

Driven by the increasing demand for passenger safety and weight reduction in the automotive industry, advanced Fe-Mn-Al-C alloys with low density and specific high strength have gained great attention in recent decades. Unfortunately, these materials are prone to hydrogen embrittlement (HE) which impedes their further application. Here we focus on a high-Mn and high-Al lightweight steel with...

The strength-ductility balance of steels is strongly dependent on their microstructure characteristic which dominates strain distribution, such as texture, grain morphology, and dispersed hard- and/or soft-phases. It is generally known that addition of Mn above 10% decreases stacking fault energy, which results in the occurrence of γ→ε→α’ martensitic transformation. The microstructure formed...

The transformation stasis (TS) phenomenon refers to the occurrence of incomplete transformation by exhaustion of a driving force while a phase transformation proceeds, which was observed during isothermal bainitic transformation. However, in the present study, the TS phenomenon was observed during athermal γ austenite → ε martensitic transformation in a high Mn alloy. Namely, γ → ε martensitic...

9%Ni steels, which have excellent strength and toughness in the low temperature range, are used as the cryogenic steel mainly used for LNG storage tanks, Mn is similar to Ni as an alloying element in steels, such as improvement of hardenability and stabilization of γ, so that Mn is expected as an alternative element to Ni. However, because the addition of Mn to steel causes remarkable...

Previously, some of the problems of cracking as well as edge cracking during two phase 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...

Medium manganese sheet steels show an excellent combination of strength and ductility. Typically, they have a duplex type microstructure consisting of ferrite and austenite layers after cold rolling and subsequent intercritical annealing. The thermomechanical rolling produces a mixture of bainite, martensite and retained austenite instead of typical duplex microstructures. Their forming...

Metal additive manufacturing (AM) received enhanced scientific and industrial importance during the last decades, mostly due to the geometrical flexibility offered by AM. The development of novel, process-adapted metallic alloys is a key for further industrial implementation of AM. We address the computational and experimental development of new high-manganese steels with properties superior...

Austenitic high manganese lightweight steels emerge as a potential candidate for structural applications in the automotive industry. The precipitation of κ-carbides in these materials upon age hardening treatment offers a great combination of strength, ductility and toughness, while the high Al content (8-11 wt. %) reduces the specific weight. In general, the size of κ-carbides at grain...

The intercritical annealing approach is widely used as a heat treatment for the formation of a dual-phase structure, composed of ferrite and austenite in medium-Mn alloys. By controlling the temperature, it is possible to control a fraction of both phases. Then, during deformation, the austenite undergoes martensite transformation, enhancing the plasticity of the steel. Depending on the...

High-manganese steels (HMnS), which are the member of advanced high-strength steel (AHSS) class, stand out due to their ability to exhibit both high strength and ductility. They are identified as promising alloys for additive manufacturing, which is a novel method enabling the production of metallic structures with complex geometries such as lattice (cellular) structures for lightweight...

In situ tensile and reversed cyclic tests were run on a TWIP steel in a SEM, with High-Resolution Digital Image Correlation (HR-DIC) measurements of the plastic strain field in a few selected grains prone to twinning, with a spatial resolution between 150 and 250nm, or under an AFM, with measurements of surface steps height at emerging deformation twins. Evidences of detwinning upon load...

Medium-Mn steels (MMnS) with very low (≤ 0.05 wt.%) carbon content exhibit improved cold-formability but limited strength due to the deficient strain hardening. A combination of nano-precipitation and enhanced transformation-induced plasticity (TRIP) effect is a promising approach to improve the strength and ductility of such MMnS. In this study, a low-carbon (0.05 wt.%) medium-Mn steel (MMnS)...

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N alloyed austenitic stainless steels are known as good candidates for replacing commercial austenitic stainless steels (STS) like AISI 304 and 316, etc due to their high strength, excellent pitting resistance with low Ni content. Austenitic steels containing (10-20)Cr, (10-20)Mn and (C+N)>0.3% manufactured by conventional vacuum induction melting have been studied intensively for the last 2-3...

Abstract: Advanced austenitic stainless steels are a group of austenitic stainless steels with a nickel content near or higher 30 wt% and a pitting resistance equivalent number (PREN) is near or higher than 40. They are widely used in the oil-gas and chemical industries. Due to high Ni content, these alloys are costly. Mn and N are two low cost alloying element for austenite stability. In this...

This paper presents the results of recent investigations on the influence of the hot press forming (HPF) temperature cycles for a novel medium manganese, high ductility 1000MPa zinc coated steel (HQ1000-GI), with specific emphasis on the risks of liquid metal embrittlement (LME) induced cracking during resistance spot welding (RSW).

In this study, a zinc coated 7Mn steel was hot formed...

The growing demands of weight saving, emission reduction and passenger safety in the automotive industry have promoted new concepts for medium-Mn steels design to achieve an excellent combination of high strength and superior ductility. Tailoring the microstructural evolution for mechanical enhancement requires deep understanding of austenite reversion mechanism. The previous research work on...

1. INTRODUCTION
   Herein, the structural and chemical features of passive films formed on a high Cr-added high-Mn 18 (wt%) twinning-induced plasticity (TWIP) steel and on two different austenitic stainless (304L and 316L) steels were revealed via Cs-corrected scanning transmission electron microscopy (STEM) and atom probe tomography (APT).

2. EXPERIMENTAL
   With a goal of increasing the...

In the last decade, the academic community extensively researched medium-Mn steels. This steel class has proved their position as one of the possible successor to classic AHSS due to excellent mechanical properties paired with still reasonable alloying costs. Nevertheless, several technical issues have to be resolved in order to enable a successful application of medium-Mn steels in a vehicle,...

Hot rolled medium Mn steel was arc welded by employing a E-71T-GS flux cored filler in a butt joint with 3 mm in thickness. The initial microstructure of the sheet was composed of martensite and very little amount of austenite, the ultimate tensile strength in this condition was close to 1600 MPa with a negligible elongation. A post-heat treatment of intercritical annealing was proposed in...

The effects of starting microstructure and intercritical annealing (IA) temperature on the phase transformation kinetics and microstructural evolution of a prototype Fe-0.15C-5.56Mn-1.1Si-1.89Al medium-Mn third-generation advanced high strength steel (3G AHSS) were determined. The starting microstructures comprised i) an as-received cold rolled (CR) microstructure containing a significant...

The microstructure and tensile properties of an arc welding joint of a Medium Mn steel, with nominal composition of Fe-0.12C-1.7Al-1.8Si-10.4Mn-0.14V (wt%), before and after intercritical annealing (IA) treatment were analyzed. An E-71T-GS flux cored filler was used to weld with a butt joint the medium Mn sheets of 3mm thickness. The initial microstructure of the sheet was composed of retained...

In this work, it was shown that quenching and partitioning (Q&P) processing can be applied to interstitial alloyed CrMnNi austenitic steels capable of martensitic transformation during cryogenic cooling. With the aid of Q&P, ultra-high strength properties can be achieved with exceptional elongation even in the as-cast state. In the present study, the alloy Fe-15Cr-3Mn-3Ni-0.16C-0.12N...

It is state of the art, that the corrosion resistance of stainless steels is mainly controlled by the alloying elements Cr, Mo and N. Derived from that, the widely applied pitting resistance equivalent number (PREN), is used to estimate and compare the pitting corrosion resistance of such steels. -
In this work, the focus was laid on the role of the Mn influence on the passive layer....

The development of new-generation AHSS steels requires a careful optimization of their processing parameters. In the case of intercritically annealed medium-Mn steels, parameters as the initial microstructure, annealing time and temperature and cooling and heating rates are paramount in controlling the final response of the microstructure.
The present research concerns with the effect that...

Here, we suggest a new thermomechanical process, which is referred to as resetting process, to recover the reduced ductility in cold-worked medium-Mn steel. The objective of the present study is motivated by the fact that one automotive component sometimes requires the two different parts for compensation of opposing attributes. For example, the upper part of center pillar needs a high...

Medium-Mn steels belonging to the third generation of Advanced High Strength Steels (AHSS) are the most perspective lightweight materials for body-in-white automotive parts. These steels containing between 3 and 12 wt.% of Mn show a beneficial combination of high strength at sufficient ductility. Their excellent mechanical properties are attributed to the substantial fraction of metastable...

Product quality, throughput, as well as energy and resource efficiency are the most important requirements in steel production. In order to meet these requirements, typically more than 15 parameters such as temperature, energy consumption and composition of the steel are monitored and the process is adjusted accordingly. The slag analysis results however, are due to extensive homogenization...

The plastic deformation of solution annealed Fe-17Cr-8.6Mn-4Ni-0.17N-steel (concentrations in wt.%) and the resulting strain-induced α´-martensite evolution were investigated at different tensile test temperatures to provide an estimate of martensite formation during tube manufacture. For this purpose, the onset and evolution of α´-martensite were determined by in situ magnetic measurement...

Application of the double soaking treatment to medium-Manganese (Mn) steels has been shown to result in impressive combinations of tensile strength and uniform elongation. The two-step double soaking heat treatment is intended to produce an austenite-martensite microstructure by intercritical annealing followed by secondary soaking. The intercritical annealing step serves to partition Mn from...

This paper will present the effects of substrate chemistry and process atmosphere pO2 on the selective oxidation and reactive wetting of a series of prototype 0.2C-6Mn-xSi-yAl-zCr third-generation advanced high strength steels (3G AHSS). The substrates were first austenitized and quenched to room temperature, flash pickled, intercritically annealed and galvanized, where all annealing...

To increase the yield strength of HMnS and afterwards regain the capability for residual deformation we developed a novel thermomechanical treatment to manufacture a high manganese TRIP steel with excellent mechanical performance by combining the deformation-mechanisms SLIP, TWIP and subsequently activating the TRIP-effect. Our process resulted in ultra-high tensile strength of the high...

Segregation engineering by controlling the solute decoration state of certain interfaces has recently been proposed as a new method to tailor mechanical properties in metallic materials. Despite the advancements in thermodynamic understanding of grain boundary segregation, the segregation behaviour at phase boundary in multiphase steels has largely remained untouched. Such information is...

Maraging steels have been widely used for the industrial application needed high strength materials such as aerospace technology and military industry. The corresponding steel is generally composed of substitutional elements such as 17-19 % Ni (in weight percent), and 8-12 % Co, 3-5 % Mo and 0.2-1.8 % Ti, and it contains a small amount of C (< 0.03 %). After hot rolling and subsequent aging,...

Understanding the deformation behavior of metals over a wide range of strain rates is of critical importance in a variety of engineering applications, such as vehicle collision, projectile penetration, explosion shock, and so on. Decades ago, studies on the strain rate dependent deformation behavior of various metals, including bcc metals (e.g. pure iron), fcc metals (e.g. Cu, Ni), and hcp...

While excellent compromise of strength and ductility of Medium Mn third generation steels are well known and deeply studied, the understanding of intergranular brittleness observed at different stages of the manufacturing process remains a major challenge for the industrialization of these new steels. Recent studies carried out at ArcelorMittal on a third generation Medium Mn 0.15C-4Mn-1.5Si...

The objective of the present study is to develop the steels with the reasonable materials cost to replace the Fe-9Ni (wt.%) steel known as the materials for the cryogenic application. We designed the Fe-xMn-yNi-0.1C steel, and the quenching-tempering (QT) process and quenching-lamellarizing-tempering (QLT) process were applied to corresponding steel to optimize the microstructure and...

A decarbonized energy system is underway worldwide. The Paris Agreement was adopted by 196 Parties at COP 21 in Paris. Its goal is to keep global warming “below 2 °C above preindustrial levels, and to pursue effort to limit the temperature increase even further to 1.5 °C.” To achieve this long-term temperature goal, big changes are needed in the ways energy is produced, distributed and...

Press hardening of manganese-boron steels is one of the most efficient production processes for high strength automotive components. However, the residual formability of these sheet components is greatly limited by the formation of fully martensitic microstructure during in-die quenching, which makes them only to a limited extent suitable for crash-relevant anti-intrusion parts of the vehicle...

A novel medium Mn steel with 8 wt% Mn was developed and processed through hot rolling and intercritical annealing. The steel possessed tensile properties of 1 GPa yield strength, 1.13 GPa tensile strength and ductility of 41%. The TWIP+TRIP mechanism was found to be operative in this steel. By further cold rolling the steel after intercritical annealing, the strain hardening rate was found to...

The effect of QP heat treatment on the phase transformation of Fe-8Mn-2.5Al-0.5Si-0.2C-1.6Cu (in wt.%) medium manganese steel was studied by thermal dilatometer and EBSD characterization. It was found that the key factor determining the microstructure (phase content) of QP heat treatment of medium manganese steel is quenching temperature. When the quenching temperature is low, a small amount...

Materials used in the oil and gas industry are often exposed to some of the most aggressive industrial environments as the industry has moved towards increasingly more challenging prospects including high pressure, high temperature, ultra-deep water, and severe sour environment. Developing these prospects at a competitive cost while maintaining robust structural integrity is one of the most...

Quenching and partitioning (Q&P) process has shown a great potential to achieve enhanced tensile properties in advanced high strength steel (AHSS). It is primarily attributed to the retained austenite in martensitic matrix that exhibits TRIP effect. In order to obtain austenite in the final microstructure, the cold-rolled steel is austenitized and then quenched to the temperature between Ms...

During the last years, Quenching and Partitioning (Q&P) steels have gained strong interest in the steel industry due to their promising lightweight potential and crashworthiness. With their microstructure consisting of tempered martensite (α’’) and C-enriched retained austenite (RA), they are characterized by balanced ductility characteristics, which close the gap between the conventional Dual...

Steels used in several aerospace applications, specifically landing gears, require high strength and fracture toughness, good ductility and corrosion resistance. However, currently used steels such as 300M and SAE 4340 are not corrosion resistant and therefore a coating is needed. Recently, a new non-toxic zinc-nickel coating is being developed; however, neither zinc-nickel coating nor...

In a thermal cycle consisting of a quenching and partitioning (Q&P) process, followed by a subsequent galvannealing process, the effect of Si and Al especially on the retained austenite in the microstructure was investigated by two alloy concepts 0.2C-4Mn-1.5Si and 0.2C-4Mn-1.5Al. Thereby the influence of a replacement of the alloy element Si by Al and their carbide retarding effect was...

Floating production assets rely on mooring chain integrity to ensure safe operation. The offshore industry has identified a number of technical gaps in the industry’s knowledge on mooring chain integrity. This has limited the ability of designers and operators to reliably estimate the degradation of mooring chain and to mitigate the risk of mooring line failures. The current code of practice...

As medium manganese steels are often treated in the intercritical domain to obtain bimodal retained austenite and ferrite microstructures, the application of a quenching and partitioning treatment to a medium manganese steel also promotes the retention of austenite at room temperature via carbon partitioning from martensite to austenite and by the austenite stabilizing effect of manganese in...

Medium Manganese steels represent an important family of steels that, if successfully implemented, can contribute toward enabling light weighting for increased fuel economy and extended electric vehicle range. Attractive tensile properties are obtained albeit highly sensitive to processing path. A review will be presented highlighting physical metallurgy fundamentals of medium manganese...

The changes in the martensite structure of 0.1-0.2%C-2%Si-5-7% Mn steels with a decrease in the prior austenite grain size were investigated. Particularly, the austenite grain size, at which the single variant martensite was formed, was investigated. When the prior austenite grain size was 2 micrometers, martensite with a single variant (single block) structure was formed. These results...

The development of new advanced high-strength steels is traditionally a very tedious process, involving extensive experimental investigations by which composition and processing conditions are varied in a more or less erratic manner until the desired properties are achieved. This situation has a tremendous negative impact on alloy development time and costs. The Alloyneering alloy design...

Hydrogen embrittlement (HE) is a persistent mode of failure in high-strength steels
which hinders their applicability in industry. The role of retained austenite (RA) in the
HE susceptibility of these steels is still unclear. There are two possible scenarios, firstly
since the solubility of H in austenite is remarkably larger than that of martensite, the
RA phase can act as a trap for H...

Abstract:
Samples from a medium manganese thermomechanical processed steel sheet show strongly preferred crystallographic orientations far from the random distribution. For the quantification of the retained austenite phase, a novel X-Ray diffraction (XRD) based method is presented that calculates the phase fraction from the measured texture data. By a geometrical averaging procedure in a...

Medium Mn steels is a family of new steels which present ground-breaking properties due to their ultra-fine ferritic matrix and a high amount of retained austenite when processed through intercritical annealing. The high fraction of austenite is enabled thanks to carbon and manganese partition between austenite and ferrite at high temperature. Controlling the enrichment and the stability of...

In the present work, a metastable Cr-Mn-Ni steel with deformation-induced plasticity was investigated. The influence of martensite formation on the mechanical properties of an Fe-16Cr-6Ni-6Mn (concentrations in wt-%) austenitic stainless steel was studied by tensile tests between -70°C and 300°C. As-quenched martensite formation was observed at temperatures below -30°C. Deformation-induced α'...

In recent years, most of the studies on medium-Mn steels have focused on the chemical compositions, microstructural evolution, mechanical properties, and heat treatment schedules with different C and Mn contents. The micro/nano scale grain size of medium Mn steel after austenite reverse transformation (ART) provides a challenging situation to characterize the microstructure and evaluate...

Excellent combinations of strength and ductility have been observed in complex phase medium Mn steels, due to the activation of TRIP and TWIP in retained austenite, stabilized at room temperature via C and Mn partitioning. Limited attempts have been made in the past to model the deformation behavior and transformation kinetics of medium Mn steels. Previous studies relied on fitting the...

3rd generation AHSS (advanced high-strength steel) family encompasses different innovating microstructure concepts, among which medium Mn steels. They have ground-breaking properties due to their particular microstructures containing a nanostructured ferritic matrix and a large amount of metastable retained austenite. Under mechanical solicitation, strain induced martensitic transformation of...

High manganese steels are considered to be promising alloys for light weight applications due to their high strength and good ductility based on their special microstructure. During plastic deformation the mechanisms of twinning induced plasticity (TWIP) and transformation induced plasticity (TRIP) lead to a strong microstructure refinement within the material. Previous studies have shown that...

To control the production processes and design product properties of promising medium and high Mn steels, reliable solidification and material models are essential. High precision and experimentally validated thermodynamic data are essential data sources for all these models. As manganese is a segregating element, it is crucial to describe high manganese concentrations well, e.g. for the final...

Third generation Advanced High Strength Steels (AHSS), among which medium Mn steels, have potential applications for the automotive industry, due to their high balance between strength and ductility and their excellent forming properties. These good mechanical properties are possible thanks to the presence of a high amount of metastable retained austenite, which will transform into martensite...

In the past decade, many efforts have been paid to improve the product of strength and elongation of medium Mn steels (containing 3~12 wt% Mn). Due to smelting difficulty and cost reasons, the application of higher Mn steels is limited. In this paper, an Nb-microalloyed 4Mn medium Mn steel, Fe-4Mn-2Al-0.2C-0.02Nb (0.02Nb steel), was prepared and short-time annealing toughening was achieved....

The goal of the research carried out using static and dynamic FWM and HPB methods was to obtain material characteristics, and most of all a detailed analysis of changes occurring in the high manganese steel microstructure in a broad range of deformation rates and deformation magnitudes. The research confirmed that deformation of steel in the static range occurs mainly via dislocation glide. It...

The influence of La additions on the microstructure and high temperature oxidation of austenitic steels Fe-20-25Mn-10-12Al-1C (wt.-%) has been investigated. Three different alloys were produced from commercially pure metals by an arc furnace with a water-cooled copper hearth and a non-consumable tungsten electrode. The melting was performed in an Ar atmosphere (99.98% purity) additionally...