| 摘要 |
PROBLEM TO BE SOLVED: To produce a steel sheet excellent in deep drawability at a high yield and low cost by coiling the steel sheet containing a specified composition of C, Si, Mn, P, S, Al, N, Ti, Nb and B after heating, rough-rolling and finish- rolling successively under specified conditions. SOLUTION: This steel compositions contained by wt.% of <=0.05% C, <=0.3% Si, <=1.5% Mn, <=0.05% P, <=0.02% S, <=0.1% Al, <=0.005% N and one or more kinds among 0.003-0.2% Ti, 0.001-0.1% Nb, 0.0001-0.01% B and the balance Fe with inevitable impurities. The steel material having this composition is heated at 950-1,100 deg.C and roughly rolled at not lower than an Ar3 transformation point. Successively, the finish-rolling is started at not higher than the Ar3 transformation point and completed at 800-700 deg.C, and the cooling is executed within 5 sec. Then, in the finish-rolling, the rolling can be executed while applying lubricator and concretely, the lubrication rolling is desirable to execute so that a friction coefficient becomes <=0.2.
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