激光冲击和深冷处理对7050铝合金残余应力和力学性能的影响

Effects of Laser Shock and Cryogenic Treatment on Residual Stress and Mechanical Properties of 7050 Aluminum Alloy

研究了不同激光冲击处理后进行深冷处理以及补充低温回火处理对7050铝合金残余应力和力学性能的影响及其规律。结果表明,激光冲击能够显著提高7050铝合金的表面压应力至-260 MPa,而增加深冷-低温回火处理后表面压应力减小约23%。但合理调整激光冲击工艺参数,能够有效弥补深冷-补充低温回火处理对表面压应力的降低,其中,当激光冲击次数为3次时,增加深冷-补充低温回火后表面压应力可达-230 MPa。此外,与单一激光冲击处理相比,激光冲击-深冷-补充低温回火处理后铝合金基体、表面之间的硬度得到均匀化。深冷处理能够促使激光冲击后铝合金试样表面变形加剧,同时晶粒得到进一步细化并且亚晶界增多,使7050铝合金的强度提高。

The effects of different laser shock treatments on the residual stress and mechanical properties of 7050 aluminum alloy by cryogenic treatment and supplementary low temperature tempering were investigated.The results show that laser shock treatment can significantly increase the surface compressive stress of 7050 aluminum alloy to-260 MPa.However,the surface compressive stress decreases by about 23%after cryogenic tempering.However,the reasonable adjustment of laser shock process parameters can effectively make up for the reduction of surface compressive stress by cryogenic-supplemented low temperature tempering.Among them,when the number of laser shock is 3 times,the surface compressive stress after increasing cryogenic-supplementary low temperature tempering can reach-230 MPa.In addition,compared with single laser shock treatment,the hardness between the matrix and surface of aluminum alloy after laser shock-deep cooling-supplement low temperature tempering treatment is homogenized.The cryogenic treatment can accelerate the surface deformation of aluminum alloy samples after laser shock,and the grain size is further refined and the subgrain boundary increases,which can increase the strength of 7050 aluminum alloy.