| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which a steel sheet with high workability having a TS of 780 MPa or more and λ of 80% or more can be produced without shortening the life of an annealing furnace.SOLUTION: In a method for producing a steel sheet with high workability, after a steel slab having a composition comprising, by mass%, 0.008% or more and 0.15% or less of C, 0.01% or more and 1.5% or less of Si, 1.0% or more and 2.5% or less of Mn, 0.080% or less of P, 0.03% or less of S, 0.010% or more and 0.5% or less of sol. Al, 0.005% or less of N, 0.15% or more and 0.45% or less of V, at least one of 0.003% or more and 0.05% or less of Nb and 0.003% or more and 0.05% or less of Ti, and the balance Fe with unavoidable impurities is subjected to hot rolling at a finishing temperature of 860°C or above, the steel slab is subjected to cold rolling at a reduction rate of 30% or more to be formed in a cold rolled sheet, then the cold rolled sheet is subjected to annealing in which temperature is held at 950°C or above for 1s or more and 10 s or less, is cooled at an average cooling rate of 15°C/s, and thereafter is subjected to heat treatment in which temperature is held at 550°C or above and 700°C or below for 300 s or more and 1,000 s or less. |
