| 摘要 |
A free-cutting steel having a high content of sulfur, characterized in that it has a chemical composition, in mass %: C: 0.03 to 0.20 %, Si: 0.35 % or less (including 0), Mn: 0.30 to 2.00 %, P: 0.01 to 0.15 %, S: 0.35 to 0.65 %, O: 0.0100 to 0.0250 %, N: 0.020 % or less, Al: 0.005 % or less (including 0), N b: 0.02 to 0.20 %, one or both of V: 0.05 to 0.50 % and Ti: 0.02 to 0.20, balance: Fe and inevitable impurities, and in a cross section of the steel, sulfide-based inclusions are primary non-metal containing inclusions and hav e an average size of 50 .mu.m2 or less, and the sulfide-based inclusions are present in an amount of 500 to 1000 pieces per 1mm2. The sulfur-containing free-cutting steel, which does not need a heavy metal affecting adversely th e environment, exhibits good machinability comparable to a free-cutting steel containing a heavy metal.
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