| 摘要 |
PURPOSE:To produce a zinc hot dipped steel sheet for deep drawing having excellent longitudinal crack resistance, by heating and hot rolling a steel having a specific compsn. and pickling said steel, then soaking and holding the steel under specific conditions, cooling the steel and dipping the same in a molten zinc bath. CONSTITUTION:The steel sheet which contains, by weight %, <=0.013% C, <=0.02% P, 0.05-0.35% Mn, <=0.005% S, and 0.005-0.080% sol.Al, is added with Ti at >=0.02% and at such a ratio as to provide 0.8-3atom. weight ratio of Ti*=Ti-48/14.N-48/32.S) and consists of the balance Fe and unavoidable impurities is prepd. This steel is heated in a 1,100-1,250 deg.C range and is hot rolled at the finishing temp. controlled to Ar3 point -50 deg.C-Ar3 point +100 deg.C and is coiled in a 450-750 deg.C range. After the steel sheet is pickled, the steel sheet is soaked and held for 10-30sec in a 500-800 deg.C range and is then cooled at 4-10 deg.C/sec down to a 300-500 deg.C range; thereafter, the steel sheet is dipped in the molten zinc bath and is thereby plated.
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