Fatigue Strength of Austempered Ductile Iron Cylinders Subjected to Repeated Internal Pressure

概要

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We carried out a repeating internal pressure test on a 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 by means of roller burnishing, which affects fatigue strength. For the lathe turned specimen (not roller burnished), the fatigue life of ADI was longer than that of the as-cast sample at a high pressure. But this difference of fatigue life became less clear with decreasing pressure. At the lowest pressure, most of the specimens were unfractured at 1 X 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 pressures. After the scanning electron microscopic (SEM) observation of the fracture surface, it was clarified that most of the fracture origins were 0.1〜0.15 mm casting defects.
一般社団法人日本機械学会の論文
1993-10-15