ATOMIZED STEEL POWDER EXCELLENT IN MACHINABILITY AND DIMENSIONAL PRECISION AND SINTERED STEEL

摘要

PURPOSE: To produce atomized steel powder capable of obtaining a sintered steel small in the dispersion of dimensional variation and excellent in machinability after sintering by forming a specified compsn. in which S, Cr and Mn are compositely added and the content of O is controlled. ;CONSTITUTION: This atomized steel powder contains, by weight, 0.005 to 0.3% S, 0.03 to 0.1% Cr, 0.03 to 0.5% Mn and 0.3% O, and the balance Fe (compsn. 1). This compsn. may moreover be incorporated with one or more kinds among ≤4.0% Ni, ≤4.0% Mo, ≤0.05% Nb, ≤0.5% V, ≤0.1% Si and ≤0.1% Al (compsn. 2). The compsn. 1 or 2 may be formed into alloy powder by mixing one or more kinds among ≤5.0% Ni source, ≤3.0% Mo source and ≤5.0% Cu source thereto, executing heat treatment and diffusedly sticking the same thereto. Moreover, the same powder may be added with 0.4 to 1.5% graphite and be subjected to compacting and sintering. By using this steel powder, the sintered steel having a structure in which graphite is precipitated into pores of the sintered steel by ≥0.05% and MnS having ≤5μm grain size is present in the grains of iron and on the grain boundaries can be obtd.;COPYRIGHT: (C)1995,JPO