摘要
The effects of laser shock peening(LSP)on the microstructural evolution and mechanical properties of the Ti6242 alloy,including the residual stress,surface roughness,Vickers microhardness,tensile mechanical response,and high-cycle fatigue properties,were studied.The results showed that the LSP induced residual compressive stresses on the surface and near surface of the material.The maximum surface residual compressive stress was−661 MPa,and the compressive-stress-affected depth was greater than 1000μm.The roughness and Vickers micro-hardness increased with the number of shocks,and the maximum hardness-affected depth was about 700μm after three LSP treatments.LSP enhanced the fraction of low-angle grain boundaries,changed the grain preferred orientations,and notably increased the pole density ofαphase on the near surface from 2.41 to 3.46.The surface hardness values of the LSP samples increased with the increase of the number of shocks due to work hardening,while the LSP had a limited effect on the tensile properties.The high-cycle fatigue life of the LSP-treated sample was significantly enhanced by more than 20%compared with that of the untreated sample,which was caused by the suppression of the initiation and propagation of fatigue cracks.
研究激光冲击强化(LSP)对Ti6242合金显微组织演变和力学性能的影响,包括残余应力、表面粗糙度、维氏显微硬度、拉伸力学性能和高周疲劳性能。结果表明,LSP使样品表面和近表面产生残余压应力,表面残余压应力最大值达到−661 MPa,其影响深度大于1000μm,且残余压应力随深度增加而减小,但最大残余压应力值并非出现在样品表面。Ti6242合金的表面粗糙度和维氏显微硬度均随着冲击次数的增加而增加。3次激光冲击强化后,合金表面硬化层深度达到约700μm。激光冲击强化提高了低角度晶界的比例,改变了晶粒的择优取向,同时使近表面α相的极密度从2.41增加到3.46。由于加工硬化,LSP样品的表面硬度随着冲击次数的增加而增加,但LSP对拉伸性能的影响很小。与未处理的样品相比,LSP样品的高周疲劳寿命增加了20%以上,这是由于LSP处理导致的试件表面残余压应力抑制了疲劳裂纹的萌生和扩展。
基金
the National Natural Science Foundation of China(No.52205240).
