Is superior in resistance black denaturation and resistance white rusted characteristic the chromate filming lead content hot dip zincing steel sheet

摘要

PROBLEM TO BE SOLVED: To produce a chromate-treated lead-contg. hot dip galvanized steel sheet excellent in blackening resistance and white rust-resistance. ;SOLUTION: In this lead-contg. hot dip galvanized steel sheet prepd. in such a manner that a steel sheet is plated with a hot dip galvanizing bath contg., by weight, 0.05 to 0.3% Pb and 0.1 to 0.3% Al, and a chromate layer of 5 to 50 mg/m² coating weight expressed in terms of metallic chromium is formed on the surface, the content of Pb present in the surface layer part in the range within 0.2 μm from the surface of a hot dip galvanizing film contg. a chromate layer is ≤2.8 wt.%. The covering ratio by Cr-Zn-Pb series oxide of Pb present in the surface layer part is ≥80%.;COPYRIGHT: (C)1999,JPO