| 摘要 |
PURPOSE:To permit production of prealloyed Ni steel powder which has high compressibility and is suppressed in the content of N by subjecting water atom ized alloy steel powder contg. Ni at a specific ratio to primary annealing and disintegrating after dehydrating and drying, then subjecting the powder to secon dary annealing and disintegrating. CONSTITUTION:The water atomized steel powder contg. <=4wt.% Ni is dehydrat ed and dried and is then subjected to the primary annealing by heating to 1,000-1,300 deg.C; thereafter, the powder is subjected to the ordinary disintegrating. The powder is then subjected to the secondary annealing at 600-800 deg.C to relieve the disintegration stress of the primary annealing and to control the content of N to <=0.0015wt.%. The powder is thereafter subjected to the ordinary disinte grating. The alloy steel powder for powder metallurgy which has <=6,400pieces/ mm<2> crystal grains and has >=7.10g/cm<2> compacting density under 7t/cm<2> mold ing pressure when mixed with 1% solid lubricant.
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