Investigation On Hybrid Manufacturing Process Of Wire-arc Additive Manufacturing And Laser Shock Peening

Wire-arc additive manufacturing(WAAM)is an additive manufacturing technology with high deposition efficiency and low unit cost,which has been gradually applied in high-end manufacturing fields such as aerospace.The directly formed components often have pore defects,non-uniform microstructure,and residual tensile stress,which greatly limits the application scenarios of WAAM.This paper uses laser shock peening(LSP)to systematically study the surface LSP of different stacking fault energy(SEF)materials,the surface LSP of WAAMed components,and WAAM interlayer LSP composite process of aluminum alloy.The main research contents of this paper are as follows:Surface LSP of different SEF materials.For the typical high SFE material 7050 aluminum alloy and low SFE material 316 L stainless steel,the hardness,residual stress,tensile properties,and microstructure under different parameters of LSP were studied.It is found that the plastic deformation produced by LSP is tiny,but the depth of the deformed layer can reach more than1 mm.Under the combined action of surface hardening and residual stress,LSP increases the yield strength of the materials with scarification of the elongation.It was found that the main effect of LSP on the microstructure of the material is the generation of high-density dislocations,and with the increase in the number of LSP cycles and the increase of the pulse energy,the dislocation density gradually increases.Surface LSP of WAAMed components.The effects of LSP as a post-treatment method on the microstructure,mechanical properties,and internal defects of WAAM-formed 2319 aluminum alloy and 316 L stainless steel components were studied.It was experimentally found that LSP could convert the high-amplitude tensile residual stress on the WAAM forming surface into compressive residual stress.Moreover,the overall porosity of the as-deposited 2319 is reduced by 2/3 under the action of compressive stress and stress concentration.Under the combined effect of pore elimination and surface strengthening,LSP post-treatment increased the yield strength of 2319 and 316 L by 151.2% and 25.7%,respectively,but also caused a significant decrease in the ductility of the two materials;The fatigue life has been more than doubled.The WAAM interlayer LSP hybrid manufacturing process of aluminum alloy was studied.According to the characteristics of the interlayer LSP hybrid manufacturing technology,the forming scheme is designed and the corresponding equipment is built.Using the immersion liquid nitrogen interlayer rapid cooling and the new swing welding deposition process,the unified regulation of the microstructure,internal defects,and mechanical properties were achieved through the interlayer LSP.Among them,the use of immersed interlayer liquid nitrogen rapid cooling device can optimize the forming appearance of WAAMed 2319 and reduce the thickness of the remelted layer to 1/3 of the original;simultaneously,the porosity area is decreased by 49.55%.After swing welding,the thickness of the deposited layer is about1.5mm,and the width is 25mm;combined with interlayer LSP,the overall pore area is reduced by 87.4%.Moreover,compared with the sample without interlayer LSP,the tensile strength,yield strength,and ductility of the interlayer LSPed sample increased by 20.1%,17.0%,and27.3%,respectively,achieving a synergistic improvement in strength and toughness.It lays a theoretical and experimental foundation for further research and applying the interlayer LSP hybrid manufacturing process.