PRODUCTION OF HOT DIP GALVANIZED STEEL STRIP

摘要

PURPOSE:To improve the corrosion resistance of a hot dip galvanized steel strip for a base steel sheet to be painted after painting by passing a steel strip obtd. by hot finish rolling at a prescribed temp. through a molten Zn bath and by cooling the hot dip galvanized steel strip under prescribed conditions. CONSTITUTION:A material to be rolled is subjected to hot finish rolling at 700 deg.C-the Ar3 point. The resulting rolled steel strip is cold rolled and annealed. The annealed steel strip is passed through a molten Zn bath consisting of <=0.05% Pb, 0.1-0.3% Al and the balance Zn. The hot dip galvanized steel strip is cooled at >=20 deg.C/sec cooling rate in the temp. range of 420-300 deg.C. A hot dip galvanized steel strip suitable for a base steel sheet to be painted is obtd.