| 摘要 |
PROBLEM TO BE SOLVED: To provide a stability-providing means for a high strength steel sheet for deep drawing, excellent in resistance to secondary working brittleness as well as in baking hardenability and aging characteristics and having >=340MPa tensile strength. SOLUTION: The steel sheet for deep drawing is constituted so that it has a composition which consists of 0.0030-<0.010% C, <=0.2% Si, 0.07-0.25% Mn, <=0.05% P, <=0.015% S, 0.01-0.04% Nb, 0.01-0.1% Al, <=0.005% N, and the balance Fe with inevitable impurities or further contains 0.0003-0.0030% B and in which the amount of Ti satisfies the condition of inequality (48/14) N[%]<=Ti[%]<=(48/14)N-[%]+(48/32)S[%] and the amount of Cal.Sol.C and the amount of Mn satisfy the condition of inequality 25<=10000×Cal.Sol. C[%]-420×Mn[%]+80<=55, where Cal.Sol.C[%]=Total.C[%]-(12/93)Nb[%] is satisfied. Moreover, this steel sheet can be produced by subjecting a steel slab to hot rolling and to coiling at low temp. and then applying cold rolling and recrystallization treatment by continuous annealing to the resultant steel plate.
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