| 摘要 |
PURPOSE:To manufacture super deep drawing steel sheet having r value with remarkably little anisotropic property, by continuously annealing the extremely low carbon steel containing Si, Mn, P, Al, N, Ti and Nb at the temperature under AC3 transformation point, after said sheet is hot rolled and cold rolled. CONSTITUTION:To the steel consisting of C<=0.007%, Si<=0.8%, Mn<=1.0%, P<=0.1%, Al; 0.01-0.10%, N<=80ppm and unavoidable inpurities, Ti and Nb are added by following. That is, contained amount of Ti is obtained by next formulas. 48/14 (N%-0.002%)<Ti and Ti%<(4.00C%+3.43N%). Nb amount is obtained by next formulas. Nb%>2.33C% and Nb%=0.003%-<0.025%. Thus, the steel to which Ti and Nb are added is continuously annealed at the temperature above 700 deg.C and under AC3 transformation point, after said steel is hot rolled and cold rolled, thereby super deep drawing steel sheet having high r value (Lankford value) with little anisotropic property may be manufactured. |
