Author(s)

H. Nisitani, R. Imai & K. Okuzono

Abstract

Physical meaning of the fatigue limit of specimens polished circumferentially or longitudinally under rotating bending H. Nisitani,* R. Imai,& K. Okuzono^ "Faculty of Engineering, Kyushu University, Fukuoka, 812 Japan ^Kurume National College of Technology, Kurume, 830 Japan ABSTRACT Rotating bending fatigue tests were made on specimens which were polished longitudinally or circumferentially with two kinds of silicon carbide papers. The material used was a quenched and tempered SCM435 steel. The specimen surfaces were observed by the two stage plastic replica method. The effects of surface polishing on the fatigue strengths of the specimens were investigated. The main results obtained are as follows: (1) Non-propagating micro-cracks are observed on the surfaces of the specimens after l(f cycles of the fatigue limit. In specimens polished under different conditions, the physical meaning of the fatigue limit o* is the same. That is, it can be defined as the limiting stress

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