高温疲劳强度与J积分关系的探讨

Approach to Relationship between Elevated Temperature Fatigue Strength and J Integral

建立了时间依存性疲劳、循环数依存性疲劳和蠕变疲劳交互作用下裂纹扩展速度及 寿命的评价公式，并用灰铸铁的试验数据作了验证。结果表明，所建立的寿命法则对高 温低周疲劳和热疲劳都成立；其同相和Ｃ－Ｐ型试验点均落在同一条△Ｗｃ－Ｎｆ线上， 而异相和 Ｐ－Ｃ型的都落在△ Ｗｆ－Ｎｆ上；但若用 △ Ｊｔｏｔ表征裂纹扩展，则可将高温 下不同类型的疲劳归纳到同一条△Ｗｔｏｔ－Ｎｆ线上。

In this paper, the evaluating law of the crack propagation rate and the fatigue life of the time dependent fatigue, the cycle dependent fatigue and the creep-fatigue interaction is set up. Moreover, it has been tested and verif-ied by the experimental data of grey cast iron. The results show that the life evaluating law is suitable for both the isothermal fatigue and thermal fatigue, its in-phase and C-P type experimental points all fall on the same △Wc-Nf line, and at the same time, out-of-phase and P-C type experimental points all fall on the same △Wf-Nf line; but if △jT is used to characterize crack propa-gation, the different types of fatigue at elevated temperature can be carranged on the same △WT-Nf line.