アルミナ分散強化銅の室温および350℃における疲労挙動と疲労寿命に及ぼす応力変動の影響

概要

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In order to investigate the influence of stress change on the fatigue behavior and fatigue life of an aluminum oxide-dispersion-strengthening copper alloy at elevated temperature, rotating bending fatigue tests were carried out under two-step loading at room temperature and 350℃. Both of static strength and fatigue strength decreased at 350℃. However, at the same relative stress σ_a/σ_B, fatigue life was longer at 350℃ than at room temperature. Although the cumulative ratios Σ(N/N_f) were nearly unity for both the low to high and the high to low block loadings at room temperature, Miner's rule did not hold at 350℃. These results were related to the stress dependence on the log l-N/N_f relation. That is, the crack length initiated at the same N/N_f was larger in higher stress level at 350℃, whereas there was no stress dependence in the relation at room temperature. The stress dependence on the relation at 350℃ was caused by the suppression of crack initiation due to the surface oxidation.
社団法人日本材料学会の論文
2004-02-15