Advances in Zinc-coated Sheet Steel Processing and Properties : Advances in Zinc-coated Sheet Steel Processing and Properties
Sponsored by: AIST Metallurgy—Processing, Products and Applications Technology Committee
Program Organizers: Frank Goodwin, ILZRO; Joseph McDermid, McMaster University
Tuesday 2:00 PM
November 3, 2020
Room: Virtual Meeting Room 40
Location: MS&T Virtual
Funding support provided by: AIST Galvanizing Technology Committee
Session Chair: Frank Goodwin, International Zinc Association
2:00 PM Keynote
Role of Liquid Zn and α-Fe(Zn) on Liquid Metal Embrittlement Cracking of Resistance Spot Welded Medium Mn Steels: Yeongdo Park1; Siva Prasad Murugan1; Ji-Ung Kim1; Junsu Kim1; Ilguk Jo1; 1Dong-Eui University
Zn assisted liquid metal embrittlement (LME) demands investigations on the influence of Fe-Zn interaction and resulting phase composition on LME behavior. Therefore, this research aims to derive the correlation between microstructural changes such as α-Fe (Zn) and the liquid zinc fraction and LME cracks that appear during resistance spot welding of galvanized medium manganese steel. The results indicate that the LME cracking behavior during resistance spot welding was governed by the fraction of effective liquid Zn, which was a consequence of isothermal solidification owing to the thermodynamic stability of liquid Zn, the diffusivity of Zn in Fe and partitioning coefficient of liquid Zn. Moreover, LME was influenced by the breaking of α-Fe(Zn) layer, which directs the liquid Zn into the substrate steel in the welds.
2:30 PM
Effect of Hot Press Forming on Electrochemical Properties of Galvanized Steel: Jaime Jewer1; Joseph McDermid1; Joseph Kish1; 1McMaster University
Vehicle light weighting is a driving force for the use of advanced high strength steels for automotive purposes. The process of hot press forming galvanized steel creates intermetallic iron-zinc phases from the original Zn coating. These phases are gamma and zinc ferrite which provide different extents of cathodic protection required for corrosion control. An experimental grade of press-hardenable galvanized steel was created to provide target mechanical properties as well as cathodic protection. During press forming, die friction negatively effects the ability of the galvanized coating to provide cathodic protection. Electrochemical test methods were used to determine the extent of cathodic protection in each region of the U-channel part for several annealing times by comparing corrosion potentials of the coating in each condition with that of the bare steel. A salt spray test was carried out to track the extent of corrosion on the part.
3:00 PM
The Effect of Galvanizing Sheet Steel under SHS Conditions on the Development of Steel Microstructures: Borys Sereda1; Dmytro Sereda1; Irina Sereda1; 1Dneprovsky State Technical University
This work considers the preparation of a zinc coating doped with aluminum under conditions of self-propagating high-temperature synthesis (SHS) for automobile parts. In order to increase the corrosion resistance of sheet steel used in the automotive industry, zinc coatings were doped with aluminum at temperatures of 550-650 ° C. When galvanizing under SHS conditions, δ1, G phases, Fe2Al5 and FeAl3 are formed. An analysis of the microstructures showed that the zinc coating forms uniformly. With increasing strip thickness and temperature, the amount of aluminum in the layer increases. Coating adhesion is also increasing. Galvanizing a steel strip under SHS conditions helps to obtain a high-quality diffusion coating on its surface. Hardening of the surface layers of carbon steels allows one-and two-phase zinc coatings alloyed with chromium with a corrosion resistance of 37-53% to be obtained more than after galvanizing by the galvanic method.
3:30 PM
Reduction of the Internal and External Oxidation of the Charge during Galvanizing under SHS Conditions: Borys Sereda1; Dmytro Sereda1; 1Dneprovsky State Technical University
This scientific work describes the study of the production of zinc coatings on sheet steels during their processing in zinc SHS mixtures. Galvanization in SHS - mixtures is a combination of gas-phase and liquid processes. To reduce the oxidation of SHS - blends, small amounts of aluminum and silicon were introduced into their composition. Alloying zinc coatings with aluminum and silicon contributes to the production of high-quality coatings with high reflectivity and adhesion. Zinc SHS - charge containing additives of aluminum and silicon is less oxidized, since a protective film of SiO2, Al2O3 is formed on its surface, which, interacting with the main components of SHS - charge, forms spinel compounds, protecting SHS - charge from oxidation. The microhardness of zinc coatings was 3800-5300 MPa. With an increase in the galvanizing temperature, the hardness of the layer increases to 5900 MPa, which corresponds to the microhardness of the δ1 phase.
3:50 PM
Zinc Coating Control Using a New Integrated Indicator ECP-Zn: Borys Sereda1; Dmytro Sereda1; Irina Kruglyak1; 1Dneprovsky State Technical University
Purpose of work was to control the quality of zinc coatings obtained on steels by the galvanic, thermal diffusion method under SHS conditions and hot. To control the quality of zinc coatings, a new developed standard ECP-Zn was used, which takes into account the operational properties, microstructure, phase composition, thickness of the zinc coating. A new zinc coating control scale has been developed, which has the following values: 0-0.15 - low quality, 0.16-0.35 - medium quality, 0.36-0.7 - high quality, 0.71-1.0 - high quality. Quality control of zinc coatings can be carried out quickly using a triopol, as well as with a complete assessment of the properties using a quatropol. New data were obtained on the structure and phase composition of zinc coatings consisting of phases: G-phase containing 25-27% by weight of iron. This intermetallic compound corresponds to the Fe3Zn10 compound with a microhardness of 5200 MPa.