オーステンパ処理球状黒鉛鋳鉄円筒の内圧疲労強度

概要

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We carried out a repeating internal pressure test on the thin wall cylinder of austempered ductile iron (ADI) which has been noted for its good combination of high static strength and elongation. We examined the effect of the austempering and surface hardening treatments using roller burnishing which affects fatigue strength. As for the lathe-turned specimen (not roller-burnished), the fatigue life of ADI was longer than that of the as-cast sample at high pressure level. But this difference of fatigue life became less clear with decreasing pressure level. At the lowest pressure level, most of the specimen was unfractured at 1×10^7 cycles ; the fatigue life of the ADI sample was shorter than that of the as-cast specimen. On the other hand, for a roller-burnished specimen, the fatigue life of ADI was longer than that of the as-cast specimen at all pressure levels. After the SEM observation of the fracture surface, it was clarified that most of the fracture origins were 0.1~0.15 mm microshrin-kages produced under the casting process.
社団法人日本機械学会の論文
1992-05-25