| 摘要 |
PROBLEM TO BE SOLVED: To provide a free cutting steel excellent in machinability and furthermore excellent in the quality of the sheared section in a bar steel and a steel wire which are sheared to prepare billets for die forging. SOLUTION: This steel is the one having a compsn. in which the contents of alloy elements are regulated to, by weight, 0.25 to 0.65% C, 0.05 to 0.50% Si, 0.60 to 0.90% Mn, 0.02 to 0.10% Bi and 0.010 to 0.035% S, contg., if necessary, 0.05 to 0.35% V, furthermore contg. if necessary, one or two kinds of 0.90 to 1.20% Cr and 0.15 to 0.30% Mo, and the balance substantial Fe, and in which the total length of inclusions having >=5μm length in 1mm<2> of the longitudinal face in a hot-rolled state is regulated to <=1.25mm.
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