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

The control of Al content in the bath of molten Zn in Continuous Galvanizing Lines (CGL) allows to improve the surface quality of coated products, particularly in the case of galvanized (GI) coating, to minimize the precipitation of Fe-Zn intermetallic particles in the bath, named dross particles, and to improve operational efficiency by increasing the process velocity. The control of Al content in the Zn bath is even more important during high-strength steels galvanizing, due to the presence of alloying elements in these steels that compete with Al for the formation of coatings with good surface quality during the immersion of steel sheets in the Zn bath. In this context, the influence of Al content in the Zn bath on the formation and surface quality of GI coating of steels with high Mn addition has been determined, in pilot scale, using a Hot Dip Process Simulator (HDPS). It was possible to assess this influence on the formation of interfacial layer, called inhibition layer, and to optimize the Al content in the Zn bath to produce GI coatings with good surface quality and adhesion to the substrate, providing conditions to achieve greater operational flexibility.