ステンレス鋼は耐熱性，耐食性にすぐれているたrnめ，各種化学工業や原子炉関係に関わる高温での構造rn部材に使用されることが多い．550℃まではマルチンrnサイト系又はフェライト系ステンレス鋼が，それ以上rnの温度ではオーステナイト系ステンレス鋼が使用されrnることが多い．高温では疲労特性は室温とは異なり，rn10~7回の繰返し数においても疲労限度が認められないrn場合や，切欠き材についても，切欠き係数が温度にrn依存するなどが報告されている．%In order to study the notch effect on rotating bending fatigue properties for SUS403 stainless steel, the rotating bending fatigue tests were carried out at room temperature, 300℃ and 600℃ with a frequency of 1 200 cycles/min. The temperature dependence of fatigue limit and the estimation method of fatigue notch factor were investigated. The relationships between the fatigue limit σ_W of smooth specimen and the tensile strength σ_B and also σ_W and the Vickers hardness HV were obtained as σ_W=0.58σ_B=1.63HV at every temperature. Furthermore the relationship between the parameter (β -1) (σ_0/σ_B)~(1/2) and Kt - 1 was proposed to estimate the fatigue notch factor, where σ_0 is the tensile strength at room temperature, β is the fatigue notch factor at a certain temperature and Kt is the stress concentration factor. Then fatigue notch sensitivity factor η was obtained as η = 0.056 (σ_B/Kt)~(1/2). Using these results, the estimated fatigue limit was satisfactory and the predicted accuracy was ±10%.
展开▼
