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研究激光冲击处理(LSP)和固溶-时效两种焊后处理工艺对7075铝合金等离子弧焊接头微观组织和力学性能的影响规律。通过固溶-时效处理工艺优化设计,确定焊接头的最佳热处理工艺为固溶(575℃,2 h)、时效(140℃,2 h),并与激光冲击处理工艺进行了对比。结果表明:焊接头经2次激光冲击后,表层焊缝区的显微硬度提高23.3%,残余应力由拉应力9 MPa变为压应力23 MPa;在热影响区,显微硬度提高44.4%,残余应力提高42.8%,抗拉强度达到607.89 MPa,与未处理样品相比提高61.96%;固溶-时效在硬度的影响层深度、断面收缩率方面优于激光冲击,而激光冲击导致裂纹源萌生于次表层,提高了焊接头的抗拉性能。
The influences of laser shock treatment (LSP) and solution-aging two kinds of post-treatment processes on the microstructure and mechanical properties of 7075 aluminum alloy plasma arc welding joint were studied. The optimal heat treatment process of the welding head is determined to be solid solution (575 ℃, 2 h) and aging (140 ℃, 2 h) by the optimization of the solution-aging treatment process, and compared with the laser impact treatment. The results show that the microhardness of surface weld zone increases by 23.3% and the residual stress changes from tensile stress of 9 MPa to compressive stress of 23 MPa after 2 laser shocks on the welding head. In the heat affected zone, the microhardness increases 44.4% The residual stress increased by 42.8% and the tensile strength reached 607.89 MPa, which was 61.96% higher than that of untreated samples. Solution-aging was better than laser shock in the influence of hardness depth and area shrinkage rate, but laser shock caused the initiation of crack In the subsurface, improve the tensile properties of the welding head.