一种定向凝固镍基高温合金的高温低周疲劳行为

Low Cycle Fatigue Behavior of a Directionally Solidified Nickel Base Superalloy

本文研究了一种定向凝固镍基高温合金的高温低周疲劳行为。结合对合金微观变形结构的观察,分析了温度、应变保持时间对合金低周疲劳性能的影响。结果表明,温度对合金的变形有着明显影响,在760℃以下合金呈现循环硬化,而在850℃和980℃时则表现为循环软化,这是由于合金在不同温度范围内具有不同的微观变形机制。在应变峰值、应变谷值以及同时在应变峰值和谷值分别引入保持时间后,合金的高温低周疲劳寿命均有一定程度的降低。

Low cycle fatigue （LCF） tests of a directionally solidified nickel base superalloy were conducted at elevated temperatures. The effects of temperature and strain dwell time on properties of the alloy were analyzed with microstructure observation. The results indicated that temperature had obvious affection on deformation of the alloy, the alloy showed cyclic hardening when temperature was lower than 760℃ and showed cyclic softening at 850℃ and 980℃. There were different deformation mechanisms at different temperature ranges. The LCF lives were always short when strain dwell induced at peak strain, valley strain or peak and valley strain.