浸炭焼入材の疲労における表面起点破壊強度の推定

概要

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Fatigue tests on carburized rotating bending specimens and carburized gears were carried out. The carburized rotating bending specimens had an oxidized layer. The fatigue tests were respectively carried out on the tooth of the gears with an oxidized layer and on the tooth of the gears without an oxidized layer. The fatigue crack was initiated from an oxidized layer on the specimens and gears with the oxidized layer. The oxidized layer played the role of a precrack. By considering the oxidized layer as a crack, an equation for estimating the fatigue strength of carburized steels with the oxidized layer was proposed. The parameters in this equation were the depth of the oxidized layer, surface hardness, and mean stress including residual stress. The fatigue crack was initiated from the surface of the tooth of the gears without the oxidized layer. The equation for estimating the fatigue strength of the carburized steels without the oxidized layer was also proposed. The parameters of this equation were surface hardness and mean stress including residual stress. Prediction accuracy was verified from these test results and other data. The fatigue strength of the specimens was estimated to be within 20% of the exprimental value, and the faigue strength of the gears was within 30%. Therefore, the prediction accuracy of the fatigue strength of the specimens was good.
社団法人日本機械学会の論文
2009-05-25