激光冲击强化对钛合金高温微动疲劳寿命的影响

Effects of Laser Shock Peening on High-Temperature Fretting Fatigue Life of Titanium Alloy

关键词:  微动疲劳  高温  钛合金  残余应力  硬度

Key words:  Fretting fatigue  High temperature  Titanium alloy  Residual stress  Hardness

摘要:

为了解高温工作环境下激光冲击强化工艺（LSP）对钛合金材料微动疲劳寿命的影响，开展了强化前后TC11钛合金在室温、300°C和500°C下的微动疲劳试验并测试了试验件表层的残余应力及硬度。结果表明：随着温度的升高，激光冲击强化对TC11钛合金微动疲劳寿命的提高倍数逐渐减小。在轴向载荷为400MPa，法向载荷为65.5MPa时，经激光冲击强化后TC11钛合金试验件在室温、300°C和500°C下的微动疲劳寿命分别为强化前的5.5倍、3.5倍和1.7倍；强化后试验件表层的残余应力会在高温下发生松弛，且松弛程度会随温度的升高而增大，这是激光冲击强化效果随温度升高而逐渐弱化的主要原因。

Abstract:

In order to understand the effects of laser shock peening (LSP) on the fretting fatigue life of titanium alloy at high temperature, the fretting fatigue test of TC11 titanium alloy before and after strengthening was carried out at different temperatures and the residual stress and hardness were tested. The results showed that with the increase of temperature, the increased times of fretting fatigue life of TC11 titanium alloy with laser shock peening decreases gradually. When the axial load is 400MPa and the normal load is 65.5MPa, the fretting fatigue life of TC11 titanium alloy specimens strengthened by laser shock peening at room temperature, 300°C and 500°C is 5.5 times, 3.5 times and 1.7 times of that before strengthening, respectively. The residual stress on the surface of the specimens relaxes at high temperature, and the degree of relaxation will increase with the increase of temperature, which is the main reason for the weakening of laser shock peening strengthening effect with the increase of temperature.