POWDER MIXTURE FOR POWDER METALLURGY, FERROUS SINTERED COMPACT, AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To improve the tensile strength, fatigue strength, wear resistance, etc., of a sintered compact without applying heat treatment by using a prealloyed type steel powder containing alloy components in amounts in specific ranges as a base powder and mixing alloyed fine powder and Ni powder with the base powder. SOLUTION: The proportion of alloy components contained in the prealloyed type steel powder is made to 1.5-4.5 wt.%. As to the proportion of these alloy components, a composition which consists of, by weight, 0.3-2.5% Ni, 0.3-3.5% Cr, 0.3-3.5% M0, 0.3-3.5% Mn and the balance Fe with inevitable impurities and in which O, C and Si among the inevitable impurities are made to <=0.3% O, <=0.02% C and <=0.1% Si is preferred. As to the alloyed fine powder mixed with this base powder, the one having a composition containing 40-70% Ni, 5-20% Cr, 5-20% Mo, 5-20% Mn and 5-15% Cu and/or Si is preferably used. Further, it is preferable to regulate the addition amounts of the alloyed fine powder and Ni powder to 1-3% and 2-5%, respectively.