为了研究激光喷丸对中高温条件下Ti-6Al-4V钛合金残余应力、微观硬度及金相组织演变的影响, 采用高功率、短脉冲Nd∶YAG激光器对Ti-6Al-4V钛合金表面进行了激光冲击, 并将冲击后的试样分别置于400℃,500℃,550℃和600℃的温度下进行了1h的保温处理。利用X射线衍射仪对强化区域的残余应力进行了检测, 通过扫描电镜及透射电镜对微观组织进行表征, 探究了强化效果与晶粒尺寸、位错运动间的联系。结果表明, 激光喷丸处理在试样表层诱导产生较大幅值残余压应力, 显微硬度提高; 经550℃热处理1h后, 残余应力影响层深约为100μm; 经400℃、600℃热处理1h后, 试样表层微观硬度分别下降了8.3HV和20.1HV; 热处理后, 晶粒尺寸总体呈现增大趋势。激光喷丸处理可以有效提高Ti-6Al-4V钛合金中高温力学性能。

In order to study effect of laser shock peening(LSP) on residual stress, micro-hardness and metallographic structure evolution of Ti-6Al-4V titanium alloy at different temperatures, Ti-6Al-4V alloy samples were treated by LSP using high power and short pulse Nd∶YAG laser and then were annealed at the temperatures of 400℃,500℃,550℃ and 600℃ for 1h respectively. Residual stress was measured by X-ray diffraction (XRD) method and metallographic structures were characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The correlations between strengthening effect and grain size, dislocation were studied based on microstructure observations. The results indicate that high amplitude of residual compressive stress is induced on the surface via laser shock peening and micro-hardness is increased significantly. After the 1h preheating of 550℃, the effect depth of residual stress is about 100μm. After the 1h preheating of 400℃ and 600℃, micro-hardness on the specimen surface declines 8.3HV and 20.1HV respectively. After heat processing, grain size has an increasing trend in general. LSP can effectively improve mechanical property of Ti-6Al-4V titanium alloy at different temperatures.