2 1/4Cr-1Mo 鋼の高温低サイクル疲労強度におよぼす圧縮ひずみ保持の影響

概要

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The effect of compressive strain holding on the low cycle fatigue strength of 2 1/4Cr-1Mo steel was investigated at 470℃. Strain holding had generally no influence on the fatigue strength of 2 1/4Cr-1Mo steel, but exceptionally distinct life reduction was observed in the compressive strain holding tests at low strain range. This was considered not to be caused by the creep effects because the life reduction was not observed in the tensile strain holding tests, the value of creep damage calculated was very small and the distinct life reduction was also observed in the zero stress holding tests. Based on the observation of the oxide film, a mechanism was proposed to explain the distinct life reduction under the compressive strain holding at low strain range. The life reduction is closely related to the acceleration of fatigue crack initiation due to the oxide cracking. The same life reduction was not observed under the tensile strain holding at low strain range because the oxide which only negative strain was applied to was not cracked and at last spalled. Finally the fatigue life of the fast breeder reactor components was predicted on the basis of the presently proposed mechanism. Consequently the life under the compressive strain holding turned out to be 10% of that of the continuous cycling.
社団法人日本鉄鋼協会の論文
1987-12-01