非比例加载下GH4169高温多轴疲劳行为研究

Multiaxial Fatigue Behavior of GH4169 Superalloy under Non-Proportional Loadings at High Temperature

利用薄壁管拉扭疲劳试样,在高温控制应变循环加载下研究高温合金GH4169的多轴疲劳行为。高温多轴疲劳试验采用比例与非比例加载路径。在试验过程中,利用数据采集系统全程记录拉与扭的应力响应值以研究比例与非比例拉扭加载下的循环特性。研究结果表明,高温拉扭非比例加载下,疲劳寿命有明显降低;拉与扭应力响应多为循环软化,无明显的循环稳定现象。在低频加载下,由于高温蠕变效应加大,使循环软化速度加快,表现为曲线下降明显。在整个疲劳过程中,扭转应力响应分量均显示循环软化现象,而拉压应力响应分量的硬化与软化特性取决于应变加载参数。

Muhiaxial fatigue behavior of superaUoy GH4169 was investigated by using the thin tubular multiaxial fatigue specimens under proportional and non-proportional loadings at high temperature. The relationship between the cyclic stress response and the cyclic number was studied by recording the experimental data. The experimental results showed that the fatigue life was decreased under nonproportional loading. In the entire fatigue process, the torsional stress response always showed the cyclic softening. The characteristics of cyclic hardening or softening for tensional stress response depended on the strain loading paths and the loading parameters. With the cyclic number increase, the creep phenomenon was gradually showed under muhiaxial loading at high temperature.