| 摘要 |
PROBLEM TO BE SOLVED: To produce a steel sheet excellent in punching workability and shearing workability and to provide a method for producing it. SOLUTION: In hot rolling for steel contd. by weight, 0.004 to 0.01% C, <=0.05% P, <=0.02% S, 0.01 to 0.1% sol. Al, <=0.004% N, <=0.03% Ti and Nb satisfying the inequality of 1<=(93/12)×(Nb/C)<=2.5 (where Nb and C denote weight %), finish final two passes are executed at high drafts in this method for producing the steel sheet excellent in bwn resistance. The volume ratio of Nb precipitates in the steel is 0.03 to 0.1%, and the grain size of >=70% therein is 10 to 40 nm.
|
