| 摘要 |
PURPOSE:To improve the press formability by continuously casting a steel contg. specified amounts of C, Mn, sol. Al, N and >=1 kind among Ti, Nb and Zr and having specified relation between Ti equiv. and C equiv., continuously hot rolling the resulting thin billet, and subjecting it to cold rolling and recrystallization annealing. CONSTITUTION:The composition of a steel is composed of, by weight, 0.001- 0.015% C, 0.01-1.2% Mn, <0.1% sol. Al, 0.0005-0.006% N, >=1 kind among <0.2% each of Ti, Nb and Zr, and the balance Fe with inevitable impurities. The relation betwen the Ti equiv. represented by equation I and the C equiv. represented by equation II is allowed to satisfy equation III. The steel is continuously cast into a thin billet, and the billet is continuously hot rolled as it is or under auxiliary heating. It is descaled, cold rolled at >=50% draft, and subjected to recrystallization annealing at >=600 deg.C. |
