TC17钛合金激光多次冲击强化后组织和力学性能研究

Microstructure and mechanical properties of TC17 titanium alloy by laser shock peening with different impacts

对TC17钛合金激光冲击强化前后的微观组织和力学性能作了对比研究,将TC17钛合金进行同一功率密度下不同次数的激光冲击,分别利用扫描电子显微镜、透射电子显微镜、X射线衍射仪、残余应力测试仪和显微硬度计对激光冲击前后TC17钛合金的微观组织、残余应力和显微硬度进行了观察和测试。试验结果表明:TC17钛合金在不同次数激光冲击后,表面形成了剧烈塑性变形和高密度位错,晶粒细化明显,3次激光冲击后有纳米晶形成;残余应力和显微硬度都随着冲击次数的增加数值增大,且沿深度方向的变化规律基本相同;与未冲击试样相比,5次冲击后试样表面显微硬度提高了20.7%,沿深度方向300μm范围内影响明显,表面残余应力达到-644.3MPa,残余压应力影响层深度增加至1.9mm。

The microstructure and mechanical properties of TC17 titanium alloy with and without laser shock peening （LSP） were examined and compared. The titanium alloy samples were laser shock peened with different impacts at the same power density. Microstructure, microhardness and residual stress of TC17 titanium alloy introduced by LSP with different impacts were discussed by scanning electron microscopy（SEM）, transmission electron microscope（TEM）, X-ray diffraction（XRD）, residual stress tester and sclerometer. The results indicate that a great deal of high-density dislocations and grain refinement are generated in the material surface layer. After 3 impacts LSP, there are nanocrystals in the LSP zone. The microhardness and residual stress value increase with greater impacts, and the variational trend with the depth is the same. Compared with the unsettled samples, the microhardness of TC17 titanium alloy treated by 5 impacts LSP has been increased by 20.7%at the surface, with a 300 μm depth affected layer. A high compressive residual stress about 644.3 MPa is introduced with an increasing plastically affected layer by 5 impacts, and the affected depth increases to 1.9 mm.