ZINC SYSTEM PLATED STEEL SHEET EXCELLENT IN FORMABILITY AND WELDABILITY AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To produce a zinc system plated steel sheet excellent in formability and spot weldability at a low cost. ;SOLUTION: The zinc system plated steel sheet has an oxidized coating film contg. 100-1,000 mg/m2 Zn and 3-20 mg/m2 Al in an Al to (Zn+Al) ratio of 0.01-0.15 on a plating layer whose Al content is ≤0.6 wt.% and does not exceed a value (wt.%) calculated by 10/Z+0.1 in accordance with the coating weight (Z, g/m2) of plating. The oxidized coating film is easily formed by applying an acid or alkali to the surface of the plating layer and immersing the plating layer in an alkaline or acidic aq. soln. contg. sources of Zn and Al. A plated steel sheet may be anodized in the alkaline aq. soln.;COPYRIGHT: (C)2000,JPO