| 摘要 |
PURPOSE:To manufacture a steel sheet for extremely deep drawing having improved press formability by hot rolling and cold rolling a steel having a specified composition contg. Ti by a larger amount than the total amount of C and N, regulating the surface roughness of the resulting steel sheet and continuously annealing the steel sheet. CONSTITUTION:A steel consisting of <=0.008% C, <=0.10% Si, <=0.5% Mn, <=0.1% P, 0.01-0.10% Al, <=60ppm N, [4.00(C)+3.43(N)]-0.08% Ti and the balance Fe is hot rolled and cold rolled. The surface roughness of the resulting steel sheet is regulated and the steel sheet is continuously annealed at >=700 deg.C. The surface roughness may be regulated during the cold rolling. The annealed steel sheet is temper-rolled at <=0.5% draft as required. The steel may further contain a very small amount of Nb, B or Sb. By this method, a cold rolled steel sheet having superior press formability and satisfactory characteristics such as high ductility and a high r-value is obtd.
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