| 摘要 |
<p>PURPOSE:To manufacture the hot dip galvanized cold rolled steel sheet for deep drawing having excellent brittlement resistance in secondary working by subjecting a low carbon steel having a specified compsn. to which specified amounts of Ti and Nb are added to specified hot rolling, thereafter to cold rolling and to carburizing treatment to regulate the C content a solid soln. into a specified one. CONSTITUTION:A steel contg., by weight, <=0.01% C, <=0.2% Si, 0.05 to 0.40% Mn, <=0.10% P, <=0.02 S, 0.01 to 0.08% sol.Al and <=0.005% N, contg. Ti and Nb so that effective Ti content Ti* expressed by a formula Ti*=total Ti-(48/32S+48/14N) satisfies 1<=(Ti*/48+Nb/93)/(C/12)<=4.5, furthermore contg., at need, <=0.003% B and the balance Fe with inevitable impurities is heated to 100 to 1250 deg.C and is hot-rolled. The rolling is ended at (Ar3-50) to (Ar3+100) deg.C and is coiled at 500 to 800 deg.C. The hot rolled sheet is pickled, is cold-rolled, is thereafter heated to its recrystallization temp. or above in a carburizing atmospheric gas to regulate the C content as solid soln. to 3 to 30ppm. The steel sheet is continuously subjected to hot dip galvanizing, by which the hot dip galvanized cold rolled steel sheet for deep drawing having excellent brittlement resistance in secondary working can be obtd.</p> |
