激光冲击强化对TC17钛合金微观组织及拉伸性能的影响

Effect of Laser Shock Peening on Microstructure and Tensile Properties of TC17 Titanium Alloy

分别采用20、25和30 J脉冲激光冲击TC17钛合金,研究其微观组织演变、表面形貌及粗糙度变化、残余应力分布以及室温拉伸性能。研究结果表明:25 J激光冲击强化后,冲击影响层α相晶粒平均尺寸由激光冲击前的11.17μm减小到6.93μm,晶体内部产生高密度位错、孪晶以及层错缺陷,位错密度由冲击前的8.11×10^(13) m^(-2)增加到3.59×10^(14) m^(-2)。20,25,30 J激光冲击强化,试样表面粗糙度减小(0.922、0.537、0.305μm),表面残余应力增大(–213、–296、–774 MPa)。激光冲击强化后TC17钛合金屈服强度提升30～70 MPa,激光冲击强化诱导晶粒细化对TC17钛合金的抗拉强度影响较小。

A pulse laser with different energies of 20, 25 and 30 J was employed to peen TC17 titanium alloy. Microstructure evolution, surface morphology, roughness, residual stress and room temperature tensile properties were investigated. Results show that the average α grain size decreases from 11.17 μm to 6.93 μm after 25 J LSP. High density dislocations and mechanical twins are observed and the dislocation density increases from 8.11× 1013m-2 to 3.59× 1014m-2. Surface roughness decreases from 0.922 μm to 0.537 μm and further decreases to 0.305 μm while the surface residual stress increases from-213 MPa to-296 MPa and further increases to-774 MPa after 20, 25, and 30 J LSP, respectively. After LSP, the yield strength increases by 30~70 MPa, which indicates that the LSP induced grain refinement has a slight effect on the tensile properties of TC17 titanium alloy.