PURPOSE: To reduce the cost by compacting pure iron powder to a prescribed density and treating directly the green compact with steam.

CONSTITUTION: Pure iron powder contg. ≤1% components other than Fe such as C, Cu, Ni, Sn, Cr and Mo is compacted to 6.2W7.2g/cm3 density to form a ringlike green compact 1 having fine unevenness 2 on the inside and outside. The compact 1 is directly treated with superheated steam at 450W600°C without carrying out sintering and sizing. Since the steam treatment temp. is relatively low, the compact 1 is hardly deformed or shrunk. The manufacturing cost is considerably reduced because of the elimination of sintering and sizing at a high temp.