| 摘要 |
PROBLEM TO BE SOLVED: To provide a ferritic free-cutting stainless steel superior in surface-finished roughness and outgassing resistance while having adequate machinability. SOLUTION: This ferritic free-cutting stainless steel comprises, by mass%, 0.06% or less C, 0.05-1.0% Si, 2.0% or less Mn, 0.050% or less P, 0.05-0.50% S, 2.0% or less Cu, 2.0% or less Ni, 9.0-25.0% Cr, 4.0% or less Mo, 0.065-2.0% Ti, 0.0150% or less O, 0.020% or less N, 0.001-0.10% Al and the balance Fe with unavoidable impurities, while satisfying the following expressions (1) and (2): [Ti]≥1.3×[S]; expression (1) and [Mn]/[Ti]≤3;expression (2), where [Ti] is defined as a Ti content in the steel, [S] as an S content and [Mn] as a Mn content; and has a steel structure containing such sulfides as to satisfy the following expression (3): (WTi+WCr)>2×WMn; expression (3), where WTi is defined as a Ti content in the sulfides formed in the structure, WCr as a Cr content and WMn as a Mn content. COPYRIGHT: (C)2005,JPO&NCIPI
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