JPS5830934B

A process for producing a cold rolled steel strip having excellent workability, utilises a continuous annealing step and comprises hot rolling a low carbon steel slab, followed by cold rolling, heating over a temperature range from 600 DEG C to the annealing temperature with a heating rate of not less than 40 DEG C/second, and then annealing at a temperature T in the range of from 700 DEG C to the A3 transformation temperature for a specific period of time determined from the carbon content and the annealing temperature. Thereafter, the strip is initially cooled slowly with a cooling rate of less than 50 DEG C/second and then rapidly from a temperature above 600 DEG C but not higher than [T - 0.027 (T - 680) ( 2ROOT t + 23.7)] DEG C with a cooling rate of greater than 50 DEG C/second, down to an overageing temperature. Overageing is performed at between 300 to 500 DEG C, for not less than 10 seconds.