不同应变比下GH3030合金的高温低周疲劳行为

Low Cycle Fatigue Behavior of a Superalloy GH3030 at Elevated Temperature and Different Strain Ratios

对镍基高温合金GH3030在600℃进行了总应变控制的低周疲劳(LCF)试验,对不同应变比(-1和0.1)下的应力-应变滞后回线、循环应力响应、应变寿命关系及低周疲劳断口形貌进行了研究。结果表明:在高应变水平时,试验合金表现为明显的循环硬化现象,在低应变水平下,则表现先软化后硬化的现象;在不同的应变比下,应力-应变滞后回线的形状比较接近,同一应变水平下疲劳寿命差别不明显,疲劳断口裂纹扩展区均可见轮胎花样特征。

The total strain-controlled low cycle fatigue （LCF） experiment of a nickel-base superalloy GH3030 at 600℃ were performed, and the stress-strain hysteresis loop, cyclic stress response, strain amplitude-life and LCF fatigue fracture morphology at different strain ratios （R=-1,0. 1）were studied. The results show that the alloy representd cyclic hardening at high strain level while representd cyclic softening initially and then cyclic hardening at low strain level. The difference of the fatigue life at different ratios was not obvious because of the shape of hysteresis loop was adjacent, and tyre-like pattern existed at the crack propagation area on fatigue fracture at different strain ratios.