Is superior in resistance dent Characteristic and resistance surface deformation Characteristic the cold rolling steel sheet null for deep drawing

摘要

PURPOSE: To inexpensively produce a cold rolled steel sheet for deep drawing excellent in dent resistance and face strain resistance, as for the surface layer part and central part, by regulating the compsn. into the different ones constituted of C, N, Mn, Si, P, Al, Ti, Nb and Fe. ;CONSTITUTION: The average compsn. from the surface layer to 10% of the sheet thickness is regulated to the one contg., by weight, ≤0.005% C, 0.005 to 0.1% N, ≤1.5% Mn, ≤1.0% Si, ≤0.1% P, 0.005 to 0.2% Al and 0.02 to 0.4% Ti+Nb, furthermore contg., at need, 0.0002 to 0.002% B, and the balance Fe with inevitable impurities, and in which the atomic fractioral ratio of the total of TiN and NbN having ≤100Å average grain size is regulated to ≥10^-4. On the other hand, the average compsn. from a position to 15% of the sheet thickness from the surface layer to the center of the sheet thickness is regulated to the one contg. ≤0.01% N and Ti and/or Nb under the condition of {Ti/48+ Nb/93-(C/12+N/14+S/32)}0, and in which the other components are same as those in the same.;COPYRIGHT: (C)1995,JPO