PURPOSE: To obtain a pure iron powder for powder metallurgy capable of producing a high-density and strength sintered part by specifying the impurity element content of the pure iron powder, grain size distribution, grain shape and diameter of the ferrite crystal grain.
CONSTITUTION: The pure iron powder for powder metallurgy contains, by weight, ≤0.005% C, ≤0.010% Si, ≤0.050% Mn, ≤0.010% P, ≤0.010% S, ≤0.10% O, ≤0.0020% N and the balance Fe. The content of the grains of -60/+80 mesh screened by a screen stipulated in JIS Z8801 is controlled to ≤5wt.%, that of grains of -83/+100 mesh to 4-10wt.%, that of grains of -100/+140 mesh to 10-25wt.%, and that of grains of -330 mesh to 10-30wt.%. The average diameter of the coarse crystal grains of -60/+120 mesh measured according to JIS G0052 is controlled to ≤6.0, 0.75wt.% of zinc stearate is added as a lubricant, the mixture is compacted in a mold at 5T/cm2 pressure, and a green compact having ≥7.05g/cm3 density is obtained.
AKAGI NOBUAKI
HANAOKA HIROTAKA
SATO MASAAKI
TAKAI TADASHIGE
