The Influence of Different Hot-Dip Zinc Coating Types on the Gas Metal Arc Welding of Galvanized Steel Sheets

Abstract The work was focused on evaluating the influence of the structure of the protective Zn coating on steel sheets on arc welding. Two types of galvanized steel sheets were used in the experiments, HX340LAD + ZF (GA type) and HX300LAD + Z (GI type), with a thickness of 2 mm. First, the analysis of the structure of the Zn protective layer was carried out on the selected materials. After that, test welds were made using the gas metal arc (GMA) welding in the short-circuit metal transfer. The influence of the type of protective Zn coating on the occurrence of defects, the geometry of the weld, and the stability of the welding process was evaluated. From the achieved results, it can be concluded that the protective Zn layer on the HX340LAD + ZF sheet was formed by intermetallic phases Fe x Zn y -Fe concentration ranged from 19.0 wt.% (at the steel plate coating interface) up to 9.5 wt.% (on the coating surface). An Fe-Al inhibitor layer was observed at the steel sheet-coating interface of the HX300LAD + Z material, while the Fe content in the Zn coating decreased from 8.2 to 0.8 wt.% towards the surface. Better weld evaluation results were achieved on samples made on HX340LAD + ZF galvanized sheet. The welds were without porosity, and the stability parameter (electric arc stability criterion) was almost two times smaller than the stability parameter in the evaluation of the HX300LAD + Z sheet metal welding process.