FREE-CUTTING AUSTENITIC STAINLESS STEEL WIRE ROD EXCELLENT IN COLD FORGEABILITY, AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To improve the yield by giving machinability and cold-forgeability to austenitic stainless steel without using heavy metal kinds (Pb, BI, Se, Te) having bad influence on the environment, thereby performing the working of a complicated part while performing cold-forging to the part, whereas the working of the complicated part has been performed by machining only heretofore.;SOLUTION: A free-cutting austenitic stainless steel wire rod excellent in cold-forgeability includes, by mass%, ≤0.030% C, 0.1 to 2.0% Si, 0.1 to 3.0% Mn, ≤0.05% P, 0.01 to 0.04% S, 8.0 to 12.0% Ni, 17.0 to 20.0% Cr, 1.0 to 4.0% Cu, ≤0.030% N, 0.002 to 0.010% Al, 0.001 to 0.010% Ca, 0.001 to 0.020% O, and the balance Fe with inevitable impurities, wherein a composite inclusion of an oxide of a CaO-SiO₂-Al₂O₃-MnO system and a sulfide of (Mn,Cr)S having low softening point is formed by satisfying conditions of 0.25≤Ca/Al≤2.50 and 0.10≤Ca/O≤0.30 by mass ratio. Further, the ratio of the number of inclusions of sulfide and the oxide having 2 μm long-diameter in the interval from the surface layer to 1 mm depth is ≥80%.;COPYRIGHT: (C)2010,JPO&INPIT