镍基高温合金GH4169的热机械疲劳行为

Investigation on Thermo-mechanical Fatigue Behavior of GH4169 Alloy

在不同温度区间、不同条件下进行GH4169合金的热机械疲劳实验测试其热机械疲劳数据,研究了这种合金的热机械疲劳行为。结果表明:GH4169合金在热机械条件下的迟滞回线具有明显的拉压不对称性;同相位时材料承受压应力,反相位时承受拉应力。拉应力,是影响疲劳寿命的主要因素。应变幅较高时GH4169合金出现平均应力松弛,在高温半周为先循环软化后循环稳定,在低温半周始终趋于循环稳定。

The thermo-mechanical fatigue behavior of GH4169 alloy was investigated via MTS809fatigue testing machine by applied multiple test loads at different temperature range. It is found that the hysteresis loops of GH4169 alloy have obvious asymmetry in tension and compression under thermo-mechanical condition. The material bears compressive stress when the mechanical strain amplitude in phase, whilst tensile stress for out of phase. The tensile stress is the main cause affecting the fatigue life.The average stress relaxation occurs at higher strain amplitude. In the high temperature half cycle, the alloy softens first and then becomes stable. In the low temperature half cycle, the alloy tends to be stable.