Advances in Metallic Coated Advanced Steels: Liquid Metal Embrittlement and Advances in Coating Production
Sponsored by: AIST: Metallurgy Processing Products and Applications Technology Committee , AIST: Galvanizing Technology Committee
Program Organizers: Joseph McDermid, McMaster University; Frank Goodwin, ILZRO

Monday 2:00 PM
October 18, 2021
Room: A211
Location: Greater Columbus Convention Center

Session Chair: Joseph McDermid, McMaster University; Frank Goodwin, International Zinc Association

2:00 PM
Influence of Temperature on the Mechanical Behavior of TRIP1180 Spot Welds with Liquid Metal Embrittlement Cracks: Kayla Molnar¹; Kip Findley²; ¹Los Alamos National Laboratory; ²Colorado School of Mines
    In this study, cross-tension and coach peel samples of galvanized TRIP1180 were produced with various liquid metal embrittlement crack lengths (350 – 1400 μm). The cracks were characterized as Type B cracks, occurring near the shoulders of the weld. Non-cracked samples were also produced for comparison. Quasi-static testing was conducted from a temperature range of -40°C to 23°C. For cross-tension testing, temperature had minimal influence on the peak load, energy absorption and failure mode. Non-cracked samples in coach peel testing generally had lower peak load and energy absorption with decreasing temperature, and the cracked samples either followed the same trend or the average values were the same across all temperatures. Overall, the mechanical behavior of spot welds with LME cracks relative to specimens without cracks is not influenced by temperature.

2:20 PM
Liquid Metal Embrittlement in TRIP and Martensitic Ultrahigh Strength Steels: Pallavi Pant¹; Emmitt Fagerstrom¹; Benjamin Hilpert²; Holger Schubert²; Luke Brewer¹; ¹The University of Alabama; ²Daimler AG
    This presentation will describe recent results on the liquid metal embrittlement (LME) of transformation-induced plasticity (TRIP) and martensitic (MS) ultrahigh strength steels. These steels are zinc coated for corrosion protection, but during welding, they can experience LME. LME of TBF1180 and MS1500 steels was studied by hot ductility testing using a Gleeble thermo-mechanical simulator. In addition, resistance spot welding of the same steels is being conducted using standard welding cycles. Current results show that the LME sensitivity is temperature-dependent over a limited range of temperatures, from 800-850˚C. Detailed, SEM-based fractography shows that the LME is intergranular in nature. While an LME response from hot ductility testing has been observed to some extent in all of the steels studied, LME is not so far present for all steels during RSW. Further investigation of the thermal cycle and stresses during RSW is being explored using the finite element method (FEM) code SORPAS.

2:40 PM
Galvanizing Sheet Steel Under SHS Conditions for the Development of Steel Microstructures: Borys Sereda¹; Dmytro Sereda¹; Dmytro Kruglyak¹; Irina Kruglyak¹; 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.

3:00 PM
A Study on Mechanical and Super-hydrophobic Behavior of the SiO2@ZnO Nano Core-shell Based Polymeric Coating: Jaya Verma¹; Deepak Kumar¹; ¹IIT Delhi
    In the study, we have developed a highly efficient and low-cost polymeric super-hydrophobic as well as mechanically-strengthened super protective nanocoating, which can be used as a marine antifouling paint. To achieve this development, polyurethane coating formulations were successfully developed with SiO2@ZnO core–shell nanoparticles on mild steel substrate. The idea behind the synthesis of SiO2@ZnO core–shell nanoparticles was to utilize the mechanical strength of silica and the hydrophobicity of the ZnO together. In this coating development nanoparticle concentration was varied from 1% (wt) to 4% (wt) in the coating formulation. Used nanoparticles was modified by using (3-aminopropyl) triethoxysilane for betterment of the surface. Further investigation on this nanocoating has been carried out by analyzing the mechanical behavior and contact angle measurement. Developed SiO2@ZnO based polymeric nanocoating has shown improved corrosion resistance and super-hydrophobic nature (~150±2⁰) with excellent mechanical properties.

3:20 PM
Use of the New Integrated Indicator ECP-Zn for Control Zinc Coating Obtaining Under SHS Conditions: 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.