Microstructure, residual stress and tensile properties control of wire-arc additive manufactured 2319 aluminum alloy with laser shock peening

Wire-arc additive manufacturing can fabricate components with complex geometries efficiently compared with other manufacturing methods. However, the uncontrolled grain size and tensile residual stress in as-fabricated components have limited their applications. In this study, laser shock peening, an innovative surface treatment technique, was specially-combined with wire-arc additive manufacturing to refine microstructure, modify stress state and enhance tensile properties of as-printed 2319 aluminum alloy. After peening, the average grain size decreased from 59.7 μm to 46.7 μm, and the percentage of grains with low angle boundaries increased from 34% to 70%. High density of dislocations and mechanical twins were generated and resulted in the increase of micro-hardness. Residual stresses were modified from tensile to compressive state with a maximum value around 100 MPa. Yield strength was remarkably increased by 72%. This combined printing and peening manufacturing strategy provides microstructure and quality control of manufactured components for practical applications.