| 摘要 |
PROBLEM TO BE SOLVED: To obtain high joining strength by forming a member made of steel material and having a hole and a green compact composed of ferrous alloy powder or powder mixture and having a shaft, fitting the hole and the shaft together, and carrying out integral sintering with use of the green compact having a composition where the amount of thermal expansion at a specific temperature at sintering is larger than the amount of thermal expansion of the steel material. SOLUTION: The temperature at sintering is >=800 deg.C. As for fit tolerance between the hole of an outer member and the shaft of an inner member, running fit of <=5μm clearance or close fit of <=40μm interference is preferred. It is preferable that, when the outer member composed of steel material and the inner member composed of green compact are fitted together and sintered, >=2% copper is mixed with the green compact and the amount of carbon in the inner member is set larger by >=0.2% by weight ratio than that in the outer member. Further, it is preferable that sintering atmosphere is carburizing atmosphere and that, when the outer member and the inner member composed of the green compact are fitted together and sintered, a zinc- containing powder lubricant is used in compaction of the green compact and sintering is performed in a carburizing atmosphere.
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