关键词: 疲劳, 平均应变速率, 韧性, 蠕变, 寿命预测, 延性, 应变能密度

Abstract: Life prediction methods of fatigue-creep interaction are beriefly reviewed. Three fatigue-creep life prediction mod- els for stress controll mode are introduced, which are based on energy exhaustion, toughness exhaustion, and ductility exhaustion theory respectively. Data from literatures and stress controlled fatigue-creep interaction test of 1.25Cr0.5Mo steel with trapezium waveform at 520 ℃ are used to comment on these models and their applicability. The predicting precisions of three models are greatly improved comparing with traditional frequency separation technique(FS) and strain energy frequency modified approach(SEFS). The energy model is applicable to not only stress controll mode, but also strain controll mode. The ductility exhaustion model has the best life prediction precision. The mean strain rate model has very simple form, and can be applied to all stress controlled failure modes, including pure creep, pure fatigue and fatigue-creep interaction. The mean strain rate model extends the applicability of Monkman-Grant relation, and has important engineering value. At last, the ap-plication precedure of mean strain rate model is discussed.

Key words: Creep, Ductility, Fatigue, Life prediction, Mean strain rate, Strain energy density, Toughness