The alloy steel powder and its production manner null whose variation of the dimensional change in heat treatment

摘要

PURPOSE:To manufacture alloy steel powder for powder metallurgy as raw material for sintered machine parts having high strength and high accuracy by dispersing and stacking Cu, Ni and Mo on the surface of iron powder at a specific ratio. CONSTITUTION:After dispersing Cu powder, Ni oxide powder and Mo oxide powder in methyl alcohol, it is mixed with iron powder and after drying, reducing treatment is executed under hydrogen gas atmosphere, e.g., at 1000 deg.C for 1hr and after annealing, it is pulverized. The alloy powder containing 5.0-7.0wt.% Ni and 7.2-8.8wt.% the total of Cu, Ni and Mo, and having 44mum particle size on the surface of iron powder, is obtd. In this case, the dispersing stuck concn. of each alloy component of Cu, Ni and Mo to the alloy powder is made to =2.2 times of the dispersing stuck concn. of each alloy component to the whole alloy steel powder. The machine parts having excellent strength and dimensional accuracy, manufactured by sintering this alloy steel powder as raw material with the powder metallurgy, is obtd.