12th International Conference on Zinc & Zinc Alloy Coated Steel Sheet - GALVATECH 2021

Considering our frame conditions for developing and producing high quality corrosion protected steels, we cannot oversee significant changes. Environmental consciousness has risen not only since the Fridays for Future movement. Resulting legal regulations may find an echo in the way we will produce steel in the future soon, reducing our carbon footprint. Obviously, environment protection will...

Zn and Zn alloy coated steel sheets are widely used because of their good corrosion resistance. In
particular, galvannealed steel sheets are mostly used for automobile manufacturing in Japan because
of their good corrosion resistance after painting, weldability, and stampability. Furthermore, several
innovative high Mg added Zn alloy coatings with superior corrosion resistance have...

Automotive industry requirements for steels capable of enabling increasingly fuel-efficient vehicles continue to drive process technology developments for North American hot-dip and electro-galvanizing lines. Third-generation zinc and zinc alloy-coated grades have reached commercialization; higher-capability grades continue to be developed. Zinc-coated hot press forming grades have reached...

With China's economic expansion having moderated to a "new normal" pace and manufacturing industry upgrading, the total amount of zinc and zinc alloy coated steel sheets in China has remained stable, but the demand for high-end zinc and zinc alloy coated steel sheets has gradually increased. This paper gives overviews of development and application of zinc and zinc alloy coated steel sheets in...

Hot dipped zinc coated material was introduced for corrosion protection with Volvo Cars 240 series in the early 1980. Including the use of conventional hot-dipped galvanized material (GI), electro-zinc coated material (EG) and galvannealed (GA) experience of coated sheet material for automotive use has been collected over the past 40 years.
Lately there has been new additional coatings...

In the recent years the Kelvin probe technique found a steadily and quickly increasing usage in corrosion research. The main application initially was for through-paint monitoring of corrosion driven delamination. Soon after that, with the development and availability of Scanning Kelvin Probe Microscopy (SKPFM), an Atomic Force Microscopy based Kelvin probe technique, followed the application...

In recent years, steel industries have been various studies to apply ZnMgAl coatings to automobiles. Initially, the solidification experiment of ZnMgAl coating on steel was investigated by using in-situ real time x-ray scattering, we confirmed that the solidification prceeds in the order of Zn, Zn/MgZn2 binary eutectic and Zn/MgZn2/Al ternary eutectic phases. Also, we evaluated the...

In a hot-dip galvanizing line for the production of zinc-coated steel strips, the heat treatment of the strip is an important process step. In order to achieve the desired material and surface properties, the strip has to be heated according to a predefined temperature trajectory. From the viewpoint of control, this is a challenging task, in particular in transient furnace operation, e.g. when...

Under certain conditions of oxygen shortage and high temperatures as could occur after coiling a hot-rolled strip, alloying elements with high oxygen affinity can diffuse and oxidise preferably along the grain boundaries. This selective internal oxidation can be increased by additional heat induced from phase transformations in the coiled state and depends on steel composition. This diffusion...

Zn alloy-coated steels such as ZnMg and ZnMgAl have been recognized as a potential automotive materials replacing traditional Zn-coated steels such as galvanized (GI) and galvannealed (GA) steel with enhanced corrosion resistance under harsh corrosive environment. There are two representative Zn alloy coatings, PosMAC®1.5 (ZnMgAl coating) and PosPVD® (ZnMg coating) for automotive application...

The main focus of the proposed paper is on the design and efficient operation of metallic recirculating radiant tubes installed with recuperative or regenerative burners in vertical strip galvanizing lines. Premature tube failures may result in loss of production capacity arising from reduced heat input or, worse, unplanned plant shutdowns. As a galvanizing line furnace equipped with around...

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Houssem Eddine CHAIEB a,*, Vincent MAUREL a, Samuel FOREST a, Kais AMMAR a, Alain KÖSTER a, Franck NOZAHIC b, Joost DE STRYCKER b, Jean-Michel MATAIGNE c

a Le Centre des Matériaux, MINES ParisTech, 63-65 Rue Henri Auguste Desbruères, 91100 Corbeil-Essonnes, France

b ArcelorMittal Global R&D; Gent, J.F. Kennedylaan 3, B-9060 Zelzate, Belgium

c...

Stress corrosion cracking (SCC) of uncoated and AlSi-coated hot forming steel grades of 1500 and 1900 MPa tensile strength is investigated under different corrosive conditions using the VDA 238-201 step load test and the VDA 238-202 constant load test. Hydrogen charging was realized by cathodic polarization with an attached zinc coated sheet or by acid solutions.
The 1900 MPa grades show a...

While mechanical properties of zinc coatings are well-known and have been studied in detail during the last decades [1,2], the fundamental behaviour of coatings of zinc- or aluminium-based alloys is much less understood. Understanding the contribution of the different micro-phases in their complex solidification structure requires new approaches.

Nanoindentation coupled with data...

In order to meet the increasing demand for a flawless and attractively painted car, surface topography of sheet metal is becoming more and more into focus of optimization. Besides inhomogeneous painting, disturbing surface texture with long wavelength proportions can make the appearance of a coating disturbed and inferior. In order to measure and display these inhomogeneity’s, new...

ArcelorMittal Gent is one of the first steel suppliers to have invested in a fully versatile furnace with the objective to produce a high amount of third generation Advanced High Strength Steels, such as Q&P; steels. ArcelorMittal chose the ANDRITZ Group to supply the necessary equipment, in particular the ANDRITZ Selas furnace, to insure that the specific thermal and process cycles needed for...

Quality specifications for high grade textured steel and aluminium strip continue to increase. In line with its strategy of continued research and development in texturing technology, Sarclad has developed the next advance in Electrical Discharge Texturing to push roll texturing capabilities above and beyond the current requirements of the industry and into the next generation.

This...

The prevention of intermetallic dross particles like Fe2Al5 in strip galvanising is paramount in making good quality exposed automotive panels. These intermetallic dross particles can create small surface features which can adversely affect the final painting quality. The formation of intermetallic dross seems inevitable during the galvanising of steel as aluminium additions are necessary to...

With the increasing use of galvanized high-strength steel sheets in automobiles, the surface quality requirements of galvanized sheets are also increasing. When hot-dip galvanized C-Si-Mn dual-phase steel (such as DP600~DP1000) is produced, a serious orange peel-like rough surface defect appears on the surface of the steel sheet, which is mainly found in the middle area of the middle section...

The presentation will address some important elements that are leading to a change in the automotive industry. In particular, technological developments such as electrification, connectivity, autonomous driving and smart mobility have the potential to change the automotive industry in the long term. Potential implication will be highlighted.

In order to characterise the maximum possible cooling rate for AHSS with non oxidizing gas a new test bench has been constructed at VKI, combining 1 central round jet surrounded by 6 jets. The facility allows jet Reynolds number up to 200.000, value for which very few experimental data are available in the literature. Results are obtained for different normalised standoff distances Z/D (ratio...

ZnAlMg coatings produced by hot-dip galvanization process have shown superior corrosion resistant, anti-galling and wear performances. Nevertheless, currently these coatings exhibit lower cracking resistance and ductility compared to conventional galvanized zinc (GI) coatings on steel sheets during forming processes. In this study, mechanical properties and cracking behavior of ZnAlMg...

The key ways to reduce CO2 emissions in iron and steelmaking can be summarized under the general terms “Smart Carbon Usage” (SCU) and “Carbon Direct Avoidance”. SCU covers on the basis of carbon carriers as reductant incremental measures at the conventional blast furnace converter route and the CO2 mitigation measures by applying so-called “end-of-pipe” technologies like CCS (CO2 Capture and...

The work studied the effect that processing parameters have on microstructure and mechanical properties of dual-phase steel grade 980. This was achieved by subjecting steel coupons to various annealing cycles featuring different heating rates, cooling rates and intercritical annealing temperatures using a dilatometer. Following heat treatments, the microstructures and mechanical properties of...

Iron is corroded by various factors such as moisture, salt and air exposure, causing problems in the building's exterior and structure. To solve this problem, studies have been continued about rust-resistant iron. Most of the galvanized steel used for outdoor applications are coated again painting on the galvanizing layer. More than that, Magnesium-added Zn-Al-Mg coated steel sheet is...

A fast and non-destructive method based on X-ray diffraction for phase quantification in zinc alloyed coatings is presented. Post-annealed hot-dip galvanized steel sheets may contain various Fe/Zn alloys (Γ-Fe3Zn10, Γ1-Fe11Zn40, δ-Fe13Zn126, ζ-FeZn13) arranged in a layered conformation and with a predictable stacking order. Each phase within the coating has a different crystalline structure...

In continuous galvanizing lines (CGL), strip annealing temperature is, though not the only one, the most significant physical parameter in the annealing process and therefore is used as the main indicator for product qualification. Annealing furnaces today are mostly regulated by Proportional Integral Derivative (PID) controllers or with the help of static based models. Those methods, though...

Through-Process Quality Control is a quality system intended to cover the entire production line, from the liquid phase to the finishing and packaging lines of the final end product. The term “Through-Process” has been coined to specifically emphasize this idea. TPQC is a quality management system for steel production, which helps to continuously monitor and to manage quality across all...

With ever increasing targets on productivity, unpredictable down times caused by a weld break can become an important problem. Lately, partly because of drivers like the rise of multiple high strength steel grades and the retirement of highly experienced operators, we have seen CGL lines experience an increase in weld break events. Technologies like pressure sensors, current sensors, cameras...

Resistance spot welding (RSW) is the most common joining process in car body manufacturing and is frequently used to join components made of advanced high strength steels (AHSS). These steels are typically applied with a zinc coating to improve their resistance against corrosion. During the RSW-process the liquefied zinc is reported to infiltrate the grain boundaries of the steel substrate...

Advanced high-strength steel grades (AHSS-grades) of the third generation offer significant ecological and economic potential in the automotive industry for reducing automotive weight, improving fuel efficiency, and thus decreasing emissions. Their properties are based on special chemical compositions and microstructures. The annealing and galvanizing process of these grades challenges the...

In zinc coated 3rd Generation advanced high strength steels (3G-AHSS), liquid metal embrittlement (LME) occurs due to liquid zinc or zinc alloy penetration along the grain, grain boundaries and pre-existing cracks of the steel sub-surface area in the presence of critical amount of external tensile stress during resistance spot welding. Due to penetration of liquid metal, cohesion between...

A large range of digital solutions and equipment exists in order to manage quality requirements of high end products on strip processing lines. But in the end day-to-day users have to juggle between dozens of solutions and finally get lost in trying to link data from different software or finding the right tool adapted to their situation. Solving defect crises requires rather applying the...

Liquid Metal Embrittlement (LME) is a complex phenomenon which may occur during spot welding of zinc-coated Advanced High Strength Steels (AHSS) developed for the Automotive market.

Zinc or zinc alloy in liquid state penetrates along the steel grain boundaries and may cause, depending on conditions, grains’ decohesion and cracks’ initiation and propagation under given mechanical...

Efficient and effective operation of a hot dip galvanizing line depends from several technological aspects: mechanical, thermal, chemical, automation and control. The synergy and the harmonization among all aspects is the key to get the best performance in terms of productivity and quality.
Danieli is recently achieving outstanding results in their new lines, thanks to a specific focus on...

Corrosion protected galvanized advanced high strength steels with high ductility (AHSS HD) like the investigated dual phase steel (DP1200HD) tend to show an elevated risk of liquid metal cracking (LMC) during resistance spot welding (RSW). LMC is an intergranular cracking mechanism driven by temperature, tensile stresses, plastic deformation and the presence of liquid zinc. Crack initiation...

To ensure a constant high productivity and quality for the newest AHSS, Andritz developed a new generation of its Metris Advanced Furnace Control. It consists of a modular design with a newly developed cooling model and a brand new multi model predictive control.

The precise physical model for all heating and cooling sections act as virtual sensors , which gives a good insight of the...

Nowadays, automotive steel customers are more and more strict on the coating quality, especially for the exposed parts that should not have any aspect defect.
To satisfy this requirement at the exit of galvanising line, one important parameter is the cleanliness of the substrate surface after the cleaning section at the entry of the line in terms of carbon pollution and iron fines. ...

The resistance spot welding is widely employed by automotive manufacturers because of its low cost and fast process. However, when the galvanized TRIP steel plates are joined by resistance spot welding, cracks are generated by liquid metal embrittlement (LME) because the substrate gets exposed to liquid zinc. These cracks deteriorate mechanical reliability of welds and limit the application of...

Over the past two years, four CGLs have installed an online, surface cleanliness monitor system utilizing a non-contact, laser ablation technique to evaluate the contamination layer on the moving sheet. The CGL operators using the system obtain unprecedented detail about the sheet’s surface cleanliness along the entire length of each coil.

The system has been improved over the last two...

Third generation advanced high strength steels (AHSS) were developed as automotive structural materials capable of enhancing vehicle fuel efficiency and crashworthiness. The use of zinc (Zn) coated AHSS is limited by Zn-assisted liquid metal embrittlement (LME) that leads to surface cracking during high temperature processing. It has been reported that AHSSs are generally more sensitive to...

During the manufacturing of the modern high strength steels, it is very important to know the austenite level compared to ferrite at given positions in the line during the steel production. Indeed, ensuring the constancy of the austenite fraction is mandatory for the constancy of the mechanical properties of the final product.
There are several positions in the line where it is essential...

Insights into the structure of surface oxides on Zn-coated press-hardened steel (PHS) are indispensable for further processing like welding or adhesive bonding. The main oxide on top of galvanized steel is Al2O3 from the primary galvanizing process. This oxide is strongly altered during final austenitization annealing before hot-forming respectively press-hardening, depending on the annealing...

The surface quality of a finished product on a galvanizing line is a very important criteria, especially for automotive and home appliance exposed products. To control it, automatic surface inspection systems (ASIS) have been developed since many years and are installed on all galvanizing lines dealing with high product quality. A highly performant ASIS from Primetals Technologies has been...

This paper has the aim at presenting a methodology of defect root cause analysis for hot-dip galvanized coatings. It has been developed to provide a global overview of all aspects related to the Materials Science pyramid – the processing route, the material properties, the structure and in-use performance – all linked by the material’s characterization. Its final aim is to provide not a single...

Surface defects on galvanized strips are a key factor for the product quality in the flat-rolled steel industry. Some of the most notorious examples are slivers and scale defects. Correct classification and reduction of sliver and scale defects are essential for high end-product quality, lower downgrading rates, less CO2 emissions, and consequently lower costs.

Steelmakers currently use...

Jet Vapour Deposition (JVD) technology is industrialized at ArcelorMittal since mid of 2016. This technology, developed in partnership with CRM Group, constitutes an attractive technical and economic alternative to Electro-Galvanizing (EG) deposition process. JVD is a vacuum deposition process fully compatible with high line speeds, which allows the deposition on all kinds of steels of pure...

The study presented here focuses on the selective oxidation of Fe-Mn (1wt.%) binary alloy. The samples were annealed by means of a laboratory furnace with a temperature profile relevant to the galvanizing line practice. The sample was first heated to 800°C at a rate of approximately 6°Cs-1. It was kept at that temperature for 60 s before being cooled to room temperature. The gas atmosphere...

Steel manufacturers are continuously developing higher performance steel grades by optimizing the chemistry at the steelwork and by changing the process parameters, in particular the heat cycles to be applied in the annealing furnaces. In hot dip galvanizing lines, the production of the latest Gen3 AHSS require higher annealing temperatures which are difficult to be achieved by using gas fired...

Physical Vapor Deposition have now entered the panel of technologies for fabricating metallic Zn-rich coatings on steel. We have recently demonstrated that General Vapor-Phase Galvanizing can coat complex-shape steel articles after fabrication with a fully alloyed Fe-Zn coating.

Surface activation is a key step of the process because the coating results from the reaction of zinc vapor...

The selective oxidation of Boron in bake hardening steel sheet is investigated in a hot dip process simulator for a typical DFF RTF cycle with two levels of pre-oxidation. The time in the RTF (85, 125 and 220 seconds), the RTF dew point (-40, -25 and -10 oC) and the hydrogen content (1, 3 and 5 %) of the RTF atmosphere are varied. The samples were analysed with FEG-SEM, EDX and GDOES. A few...

Arcelor Mittal Cleveland Hot Dip Galvanizing line produces 260,000 metric tons of Galvannealed AHSS products (GA) annually for automotive customers. New AHSS grades and thickness gauges are under constant development for automotive applications to meet the future automotive fuel efficiency standards. The use of alloy elements such as Manganese, Silicon and Aluminum in Dual Phase and TRIP...

In industrial electro galvanizing lines, the performance of the dimensionally stable anodes (Ti + IrOx) is a crucial factor for product quality. Ageing of the anodes causes worsened zinc coating distribution on the steel strip and a significant increase in production costs due to a higher resistivity of the anodes. Up to now, the end of the anode lifetime has been detected by visual inspection...

The surface quality of galvanized steel sheets is considerably influenced by intermetallic dross particles, which inevitably form during operation. η-phase Fe2Al5 top dross and δ-phase FeZn7 bottom dross particles have been reported to be entrapped into the coating causing functional and optical defects. Moreover, particles are frequently mentioned to adhere to the stationary and the moving...

During production of galvanized products, the Hot Dip Galvanizing bath is managed with additions of ingots allowing to guaranty the stability of the bath level and composition. Hot Dip Galvanizing pot productivity (in kg/h) is then defined as the amount of materials melted in the pot during a given time. The pot productivity is generally monitored to maintain the HDG bath at a stable level and...

The main objective of the present work was to investigate the forced wetting of a partly oxidized steel by a liquid Zn - Al (0.2 wt. %) alloy. The wetting experiments are performed by means of the dispensed drop technique. The wetting is shown to be reactive with the formation of Fe2Al5Znx. The evolution of the contact angle and spreading diameter is determined as a function of spreading time....

In advanced high strength automotive steels, small amounts of diffusible hydrogen can lead to a deterioration of mechanical performances, especially a loss of ductility, in the simultaneous presence of internal stresses and of a sensitive microstructure. In the hot-dip galvanizing process, hydrogen is mainly absorbed during high temperature operations in hydrogen-containing atmospheres before...

In order to improve fuel efficiency and to reduce carbon emissions, automakers are using advanced high strength steels (AHSS) to lightweight vehicles without compromising passenger safety. In manufacturing, the steel sheet is annealed in a continuous galvanizing line (CGL) to achieve the desired mechanical properties. During annealing, alloying elements such as Si, Mn, Cr, Al, etc. in the...

One of the most important aspects for a material used in automotive industry is the reliability in service regarding corrosion resistance, safety and functionality. However, hydrogen embrittlement can cause a dramatic deterioration of mechanical properties, especially in case of advanced high strength steels (AHSS). Thus, it is essential to clarify the mechanisms of hydrogen insertion into the...

Hydrogen embrittlement of advanced high strength steels (AHSSs) in atmospheric exposure conditions is of utmost importance for automotive industry as the application of AHSSs grows steadily due to desirable mechanical properties. Different aspects of the hydrogen embrittlement phenomenon such as hydrogen entry caused by atmospheric corrosion reactions are currently under intensive research. ...

The lifetime of pot bearings is one of the major sources of maintenance shutdowns on a continuous galvanizing line. However the lifetime between different lines can be very different whereas the general process windows may look the same
A simple model is proposed to quantify the expected wear rate, considering the bearing geometry and process parameters. A viable model would help operators...

Modern automotive grade continuous galvanising lines (CGL) are presented with a significant risk when considering online trials of new galvanising bath submerged journal bearings. Such trials of submerged bearings can pose significant financial loss should untested bearing components fail, resulting in unplanned maintenance stops. This limits opportunity for hardware improvements on modern...

To improve the surface feature of high-Mn steel, such as wettability with liquid Zn, a functionally graded multilayer was fabricated on the top of as-cast high-Mn steel slab by laser cladding process. For the alloying material, low carbon steel powder (0.07C, 1.83Mn) was deposited. To investigate the optimum condition for wettability, four different samples were prepared: bare high-Mn steel...

Galvanized press hardened steel (PHS) is in serial production more than 15 years. Zinc provides excellent cathodic corrosion protection for PHS parts, but can cause Liquid Metal Embrittlement (LME) and micro cracks. One can dispose of this LME risk by using the indirect hot forming process and avoiding tensile stress at high temperatures. To eliminate LME for the direct hot forming process...

This study experimentally investigated the ability of a novel multi-slot air-knife design to reduce high-intensity tonal noise and produce thinner coating weights in the continuous galvanizing gas jet wiping process. Coating weight measurements were carried out over a wide range of operating conditions to correlate the effect of the multi-slot jet operating parameters on the final coating...

Zinc coatings offer the advantage of a galvanic corrosion protection instead of a conventional barrier corrosion protection. Thus zinc coatings prevent the corrosion of the steel substrate even in the case of a damaged coating layer. It is therefore of interest to use zinc coatings in the automobile industry particularly for components of the body in white. These components are often produced...

Zn-coated press hardened steels are in high demand in the automotive industry because their high strength enhances passenger safety while supplying robust cathodic corrosion protection. However, micro-crack formation after thermomechanical processing is an issue that limits full deployment. Thereby, the objective of this research was to determine the mechanism for micro-cracking in Zn-coated...

Direct hot press forming (DHPF) of Zn-coated steels presents significant challenges associated with avoiding liquid metal embrittlement (LME) while maintaining robust cathodic protection. As identified by previous studies, a minimum amount of the Γ-Fe3Zn10 phase (15 vol%) is necessary to provide robust cathodic protection for Zn-coated press hardening steels (PHS). The Γ-Fe3Zn10 phase is...

Grain boundary weakening caused by grain boundary wetting is a potential precursor for liquid metal embrittlement in a Zn coated press hardening 20MnB8 steel. Galvanized press hardened steel samples, deformed by bending, and not deformed (flat) steel samples were analyzed by means of electron backscatter diffraction (EBSD), Auger electron spectroscopy (AES), energy dispersive X-ray analysis...

The hot-stamping (HS) process has been widely used to produce automobile components, because of the great demand for higher strength steel sheets. Moreover, coated steel sheets, including galvannealed steel sheets (GA), are being applied as HS material [1,2]. The structural change of GA coating during the HS heating process has been researched [2,3]. However, the mechanical properties of this...

ZnAlMg (ZM) metallic coatings are already in use since the start of their development in the late 2000’s, while the production still benefits from a steady volume increase. It has been proven already that this type of metallic coatings is having an excellent corrosion resistance in divers harsh environments.

One of the highly used markets for this type of metallic coatings is the solar...

X-ray diffraction is a technique, which is widely used in material analysis. It is typically utilized in the laboratory to reveal information about the microstructure of materials.
IMS developed in cooperation with SMS group and Drever International a new measuring system, which applies the x-ray diffraction technology to the harsh environment of a production line. The new system provides...