| 摘要 |
PROBLEM TO BE SOLVED: To provide low-carbon steel of excellent machinability which is improved in service life of a tool and surface roughness, and to provide structural steel and high-strength steel having mechanical properties (including anisotropy) and machinability in combination. SOLUTION: Steel of excellent machinability has a composition consisting of, by mass, 0.001-1.5% C,≤3% Si, 0.01-3% Mn, 0.001-0.2% P, 0.0001-1.2% S, 0.001-0.5% Zn, 0.0001-0.02% N, and 0.0005-0.05% O. In addition, the steel contains 0.002-0.5% Sn and/or 0.0005-0.05% B which are machinable elements as necessary. A cost is reduced, and the production efficiency is improved thereby. COPYRIGHT: (C)2004,JPO
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