高強度鋼の疲労強度の欠陥感受性

概要

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A study has been conducted to make clear the relation between the critical size of inclusion and the length of non-propagating crack and to evaluate the true fatigue limit of inclusion free microstructure and then compare it with the conventional fatigue limit of high strength steels. The results are summarized as follows ; (1) There exists a critical size of semi-spherical surface flaw beyond which the surface flaw has an effect of reducing the fatigue strength of steels. Such a critical size (d_c) of surface flaw is nearly equal to the length of non-propagating crack in the quenched and tempered steel at medium hardness level. (2) True fatigue limit estimated for the inclusion free microstructures increases linearly with the hardness of microstructure even in the hardness level over the optimum hardness H_<v,c<. (3) The fatigue limit of ultra low oxide spring steel containing Al_2O_3 inclusions of 20 μm diameter is estimated to be about 80 % of the true fatigue limit of the ideal inclusion free steel at the same hardness level.
一般社団法人日本機械学会の論文
1988-10-25