826 S45C 材のねじり疲労特性に及ぼす予ひずみの影響

概要

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Fatigue test has been performed to investigate the torsional fatigue properties of pre-strained carbon steel (S45C). Main results summarized in this study are as follows : (1) In the case of plastic pre-strain rate ε_p≦5%, the fatigue limit is 10% lower than the non-pre-strained specimen. Even if the pre-srtain rate increases, the fatigue limit is almost the same one. (2) In the case of ε_p>5%, the fatigue limit increases with increasing pre-strain rate. For the ε_p=8%, the fatigue limit equals to fatigue limit of non-pre-strained specimen. (3) The non-propagatinig cracks are observed in all specimen's sufaces after suffered by 1×(10)^7 cycles under the stress amplitude of fatigue limit. The length of non-propagating crack of pre-strained specimen has no obvious difference with that of non-pre-strained specimen. On the other hand, the higher the pre-strain rate, the more number of non-propagating cracks are observed in the specimen's suface.
2000-07-31