激光喷丸改善TC6钛合金组织和力学性能

Improvement of structure and mechanical properties of TC6 titanium alloy with laser shock peening

为了使激光冲击强化技术能较好地应用于TC6钛合金的发动机叶片,对TC6钛合金进行试验研究。通过X射线衍射仪、透射电子显微镜等测试技术分析了不同参数下TC6钛合金的微观组织变化,用显微硬度计和残余应力测试仪分别表征表层硬度和残余应力变化,并测试材料冲击后的振动高周疲劳性能。试验结果表明:激光冲击材料后表面组织得到明显细化,随着冲击次数的增加,先后出现了高密度位错、位错胞、亚晶和纳米晶。性能方面,表面硬度在冲击一次即可提高19%,硬度影响深度达到700μm;与此同时表面残余应力最高达到-608.5MPa,在500μm深度上仍具有-100 MPa左右的应力存在。经三次冲击后,标准疲劳试片的疲劳极限提高近20%。

In order to implement the laser shock peening （LSP） technology on the TC6 titanium alloy aero-engine blade, TC6 titanium alloy was treated by LSP. Microstructural characteristics, microhardness and residual stress on the cross-section of TC6 titanium alloy after LSP were tested with X-ray diffraction （XRD）, transmission electron microscope （TEM）, microhardness tester and residual stress tester, and vibration fatigue limit was obtained by high-cycle fatigue test. The results demonstrated that the original structure was refined, and high density dislocation, dislocation cell, subgrain and nanocrystallite generated with laser impact increasing. Besides, on the aspect of mechanics performance, the surface microhardness was increased by 19% with a 700-/μm-depth affected layer under one laser impact. The greatest residual stress value was --608.5 MPa on the surface in ten impacts and at 500/μm depth the value was still above --100 MPa. With three impacts, the fatigue limit of standard fatigue specimens was improved by about 20%.