放大自发辐射对激光强化7050铝合金残余应力的影响

Effect of Amplified Spontaneous Emission on Residual Stress of 7050 Aluminum Alloy by Laser Shock Processing

利用高能高重复频率钕玻璃激光器对7050铝合金进行了冲击强化处理。研究了在激光介质抽运功率保持不变的情况下,通过改变放大自发辐射(ASE)的大小,激光冲击强化7050铝合金,并用X射线衍射技术测量7050铝合金表面产生的残余应力。结果表明,在保持激光介质抽运功率不变的情况下,ASE和铝合金表面产生的残余应力有一定的关系。随着ASE的增大,铝合金表面产生的残余压应力逐渐减小;当ASE增大到16.20 J时,吸收层铝箔已经被完全熔融,有效脉冲直接冲击铝合金表面,在铝合金表面产生21 MPa的拉应力,直接影响激光冲击的强化效果。

The 7050 aluminum alloy is processed by laser shock processing（LSP） with high energy high repetition rate Nd∶glass laser.After LSP with the unchanged pump power and different amplified spontaneous emissions（ASE）,the surface residual stress of 7050 aluminum alloy is measured by using X-ray diffraction（XRD） technology.Results show that there is a certain relationship between ASE and the surface residual stress of aluminum alloy after LSP with unchanged pump power.With the increase of ASE,the compressive residual stress of the sample surface gradually decreases.When ASE increases to 16.20 J,the absorbing layer（aluminum foil） has been completely molten,and the effective pulse directly impactes aluminum surface and generates 21 MPa tensile residual stress which directly affects the effect of LSP on 7050 aluminum alloy.