衝撃荷重下でのS-N曲線と破面様式について : 熱処理硬さの異なるS45C鋼平滑丸棒の場合

概要

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A series of impact fatigue tests were conducted for structural carbon steel JIS. S45C of different hardness ranging from H_v 166 to H_V 534. In order to investigate the S-N characteristics over a wide range of stress cycle, two types of impact fatigue testing machines were used ; one is an impact cylinder falling type with the loading rate of about 0.5 H_Z, and the other is a vibro-motor type with the loading rate of about 60 Hz. Discussions were made on the configuration of S-N curves, the fracture pattern and the effect of the difference in impact stress pattern on the fatigue life in relation to the hardness of each specimen. The main results are summarized as follow; firstly, the fatigue strength under a traingular stress pattern applied in this study was higher than that under a rectangular stress pattern with duration of the peak stress of about 0.8 msec. Secondly, the S-N curve had an obvious transitional number of the stress cycle and fracture surface patterns were found to be entirely different between in front and in rear of the transition point, that is, the ductile fatigue fracture appeared in the low cycle region and the ordinary one in the high cycle region. Besides, this transition point had a tendency to transfer from the high cycle region to the low cycle region as the hardness increased.
社団法人日本材料学会の論文
1985-09-15