摘要
针对TiAl合金开展750℃条件下的低周疲劳(low cycle fatigue,LCF)和疲劳-蠕变交互(creep-fatigue interaction,CFI)性能实验,所有实验均采用应变控制,应变比为–1,应变幅为0.4%且保持恒定,应变速率为1×10–3 s–1。对TiAl合金在高温LCF和CFI实验条件下的应力-应变稳态迟滞环、循环硬化/软化、应力松弛和寿命进行研究和对比分析,并采用Morrow修正方法和本工作提出的统一寿命预测模型对TiAl合金的高温LCF和CFI寿命进行预测,最后对TiAl合金的高温LCF和CFI试样的失效机理进行分析。结果表明:(1)与高温LCF相比,TiAl合金的CFI性能在应力-应变稳态迟滞环、循环硬化/软化现象、应力松弛行为和寿命等方面均有明显区别;(2)Morrow修正方法不能对TiAl合金的高温LCF和CFI寿命进行准确预测,而本工作提出的统一寿命模型预测寿命位于实验寿命的±1.5倍分散带以内,预测能力较高;(3)TiAl合金高温LCF和CFI裂纹均萌生于试样表面,TiAl合金高温LCF试样呈现出穿晶断裂特征,而其CFI试样呈现出穿晶和沿晶的混合断裂特征。
The strain controlled low cycle fatigue(LCF) and creep-fatigue interaction(CFI) tests of a TiAl alloy were conducted at 750 °C in air. The strain ratio, strain amplitude and strain rate were –1, 0.4% and 1 × 10–3 s–1 respectively. The high temperature LCF and CFI stress-strain stable hysteresis loop, cyclic hardening/softening, mean stress relaxation and life were studied and compared in details. Morrow modified method and unified life model developed in the present study were employed to predict the fatigue life for LCF and CFI life of TiAl alloy. Finally, the failure mechanisms between LCF and CFI specimens were compared, and some interesting conclusions were obtained. The results show that:(1) there are obvious differences on stress-strain stable hysteresis loop, cyclic hardening/softening, mean stress relaxation and life between LCF and CFI tests;(2) Morrow modified method is not able to predict the fatigue life for LCF and CFI life for TiAl alloy, however, the predicted fatigue life by the unified life model is located in the scatter band of ± 1.5;(3) the fatigue cracks are initiated from the surface for all of LCF and CFI specimens, and LCF specimens show more transgranular appearance while CFI specimens show obvious mixed appearance of both transgranular and intergranular.
作者
董成利
胡晓安
DONG Chengli;HU Xiaoan(Application Evaluation Center of Aeroengine Materials,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;Science and Technology on Advanced High Temperature Structural Materials Laboratory,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;School of Aircraft Engineering,Nanchang Hangkong University,Nanchang 330063,China)
出处
《航空材料学报》
EI
CAS
CSCD
北大核心
2020年第4期36-44,共9页
Journal of Aeronautical Materials
基金
国家自然科学基金(51401195)。
关键词
TIAL合金
高温
低周疲劳
疲劳-蠕变交互
寿命预测
TiAl alloy
high temperature
low cycle fatigue
fatigue-creep interaction
life predication
