PRODUCTION OF GALVANIZED STEEL SHEET AND ALLOYED GALVANNEALED STEEL SHEET EXCELLENT IN UNIFORM PLATING PROPERTY AND PLATING ADHESION

摘要

PURPOSE: To produce a galvanized steel sheet excellent in uniform plating properties and plating adhesion with high productivity by immersing an annealed steel sheet in a hot-dip salt bath of a specified temp. for specified time and thereafter galvanizing it. ;CONSTITUTION: A steel sheet subjected to continuous annealing is immersed in a hot-dip salt bath of ≥420°C for 10 to 60sec or is subjected to anodic electrolysis in the same hot-dip salt. As this hot-dip salt, the hot-dip salt of chloride is suitable from the viewpoints of treatability and cost, and particularly, the one contg. ZnCl₂ by 40mol% is preferable. By this immersing treatment or anodic electrolysis treatment, concentrated layers having low wettability with hot-dip zinc on the surface of the steel sheet can be removed at high efficiency. After the hot-dip salt treatment, the steel sheet 15 galvanized, and, according to necessity, it is successively heated, and iron is allayed into the plated layer.;COPYRIGHT: (C)1994,JPO&Japio