マルエージング綱の疲労強度に及ぼす微小欠陥と介在物の影響

概要

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Effects of artificial small defects (drilled hole, shallow notch and the indentation of the Vickers hardness) on the fatigue strength of a maraging steel which received various aging treatments for the attainment of various hardness levels were studied. The fatigue strength σ_w can be predicted by σ_w = 0.65(H_V+960)/(√<area>)^<1/6>………(a) where H_V is the Vickers hardness number and √<area> is the square root of the projected area of the artificial defect onto the plane normal to the direction of the maximum tensile stress. Equation (a) explains the reason of relatively low fatigue strength σ_<w0> of maraging steel even with high hardness, because the maraging steel used in this study contains spherical inclusions of TiC with approximately 10 μm diameter and the value of √<area> of TiC was estimated to be about 9 μm by the investigation of the microstructure. Substituting this value and H_V into Eq. (a), we can obtain the values of σ_<w0> which are in good agreement with the experimental results. These results suggest that the improvement in fatigue strength of maraging steel and hard steel may be achieved from the viewpoint of Eq. (a).
一般社団法人日本機械学会の論文
1987-08-25