Improved tensile strength and fatigue properties of wire-arc additively manufactured 2319 aluminum alloy by surface laser shock peening

Wire-arc additive manufacturing (WAAM) has been extensively studied thanks to its high material utilization rate and ability to form large-size components. However, due to the considerable internal porosity, the as-build (AB) parts usually exhibit poor tensile and fatigue properties. In this study, laser shock peening (LSP) was applied as a post-treatment method on WAAMed 2319 aluminum alloy. By performing LSP on the surfaces of the material, an influencing layer with a thickness of 1.3 mm was generated. The peak hardness and yield strength increased by 30.2% and 151.2%, respectively. Under the action of concentrated compressive residual stress (CRS) around the pore defects, the number density of pores is reduced by 65.3%, while collapsed large-size pores were observed. The combined effect of CRS, surface hardening layer, and defect reduction doubles the fatigue life. The “Ladder” like mutation was observed in the failure process, and its formation can be attributed to the resistance between pores and CRS.