关键词: 高温低周疲劳, 蠕变疲劳, 寿命预测, 应变范围区分法, 应变能区分法

Abstract: A total strain version of strain energy partitioning (TS-SEP) is formulated based on strain energy partitioning(SEP), utilizing the method of HALFORD and SALTSMAN for developing TS-SRP. Like TS-SRP, TS-SEP characterizes the behavior of alloys in two aspects: Failure behavior and flow behavior. Elas-tic strainrange-life relations are established by using the em-pirical equations of flow behavior of alloys. Total strainrange-life relations are given by summing elastic strain-range-life relations and inelastic strainrange-life relations. TS-SEP can be used for creep-fatigue life prediction without partitioning the inelastic strainrange, so it is applicable in the low-strain, long-life regime where SEP is difficult to use. Then, TS-SEP is evaluated and verified by using two advanced nickel-base superalloys, Rene95 at 650 ℃ and AF2-1DA at 760 ℃. The results indicate that TS-SEP can predict the creep-fatigue life of Rene95 at 650 ℃ and AF2-1DA at 760 ℃ more reliable than SEP. The agreement of the predictions with the observed lives of the baseline tests is quite good for TS-SEP, with 97.5% percent of the Rene95 baseline data being predicted to within factors of two, and 100% of AF2-1DA, and the scatter band of TS-SEP for verification tests is lower than all other three methods (SEP, TS-SRP, SRP).

Key words: Creep-fatigue, High temperature low cycle fatigue, Life prediction, Strain energy partitioning, Strainrange partitioning