中文摘要：

激光成形修复钛合金构件存在修复区晶粒粗大和残余拉应力,以及不同区域间组织及性能不均匀的问题,导致修复构件的疲劳性能明显降低。本文采用激光冲击强化技术,对激光熔覆修复试件进行了表面强化,研究了激光冲击对其疲劳强度的影响,并从残余应力和微观组织等方面分析了激光冲击提高熔覆试件疲劳强度的原因。结果表明,钛合金基体试件的疲劳强度为401 MPa,激光熔覆试件的疲劳强度为365 MPa,下降了9%;激光冲击强化后,熔覆试件的疲劳强度达到了450.80 MPa,相比基体提高了23.5%。激光冲击强化在试件表层引入了数百兆帕的残余压应力,影响层深度可达430μm,同时可使修复区的组织和性能变得均匀,从而提高了修复试件的疲劳抗力。

英文摘要：

When repaired by laser forming repair, there generates tensile residual stress and bulky grains in the repair zone of titanium alloy components, Meanwhile, microstructures and performances are ill-distributed between the repair and matrix zone. Due to all above, fatigue strength of the repaired components is reduced seriously. Laser shock processing is adopted to treat the specimens which are repaired by laser cladding. The effect of laser shock processing on fatigue strength of the repaired specimens is researched. Mechanism of the effect is demonstrated by residual stress and microstructure analysis. The results suggest that fatigue limit of the matrix specimens is 401 MPa, but that of the laser cladding specimens is 365 MPa, which decreases by 9%; while treated by laser shock processing, fatigue limit of laser cladding specimens is improved up to 450.80 MPa, which increases by 23.5%. Considerable compressive residual stress is introduced by laser shock processing in the material surface, and depth of it reaches at 430 μm. Moreover, microstructures and performances are well-distributed. Compressive residual stress and improved microstructures are the reasons for that fatigue strength is enhanced.