PRODUCTION OF COLD ROLLED STEEL SHEET FOR WORKING STABLE IN MECHANICAL PROPERTY

摘要

PROBLEM TO BE SOLVED: To produce a cold rolled steel sheet for working having uniform and excellent workability and stable in mechanical properties. ;SOLUTION: At the time of subjecting a steel sheet obtd. by executing hot rolling, pickling and cold rolling to steel having a compsn. contg., by weight, ≤0.006% C, ≤1.2% Si, ≤2% Mn, ≤0.1% P, 0.005 to 0.1% Al and ≤0.01% N, furthermore contg. either or both of Ti and Nb satisfying the conditional inequality of C/12+N/14-0.0001Ti/48+Nb/93, and the balance Fe with inevitable impurities to continuous annealing, it is heated at the average heating rate of 5 to 30°C/sec to the temp. region of 600 to 750°C, successively, rapid heating is started from the temp. region at a temp. rising rate of 60 to 500°C/sec, its temp. is raised to the annealing maximum arrival temp. of 750 to 910°C previously decided per position in the longitudinal direction of the steel sheet in accordance with the actual variation in the longitudinal direction of the steel sheet in the hot rolling condition, and annealing is executed to obtain the required material.;COPYRIGHT: (C)2000,JPO