Strengthening of wire arc additive manufactured aluminium alloy through interlayer rotary friction processing

Abstract

To eliminate porosity and refine the grains in aluminium alloys fabricated via wire arc additive manufacturing (WAAM), a novel strengthening method – robotic rotary friction processing (RFP) – was introduced. The feasibility of RFP was assessed by processing the deposited beads under various average peak loads. During RFP, a rotating tool pressed the deposited beads to induce sufficient plastic deformation. After 3.5 kN-RFP, the WAAM densification ratio was improved to >99.5%, and pores were completely closed and eliminated owing to compression deformation and sub-grains bonding. The processed deposits exhibited effective grain refinement and high-density dislocation entanglement, which led to 22.8% and 34.2% improvements in the horizontal and vertical tensile strengths, respectively. Furthermore, the strengthening mechanism of RFP on deposited metals was clarified.