Effects of ultrasonic rotating extrusion assisted wire arc additive manufacturing on the microstructure and mechanical properties of 5356 aluminum alloy

Abstract

Wire Arc Additive Manufacturing (WAAM) for the fabrication of lightweight Al alloy represents a burgeoning area of research. Despite this, the presence of porosity defects, coarse surface grain sizes, and the clustering of precipitated phases in WAAM-produced Al alloy samples have been identified as detrimental to their mechanical properties, rendering them inadequate for contemporary service requirements. In this investigation, an innovative approach termed Ultrasonic-Rotating Extrusion-Wire Arc Additive Manufacturing (U-RE-WAAM) was proposed, which integrates the synergistic effects of ultrasonic and mechanical force fields into the WAAM process. Comparative analysis were conducted on defects, microstructure and mechanical properties between WAAM and U-RE-WAAM samples to investigate the impact of U-RE-WAAM on aluminum alloy samples. The results show that the mechanical force field causes a large amount of plastic deformation, which refines the grain size and restructures the precipitation phase from clustered aggregates to a fine dispersion. Furthermore, the U-RE-WAAM process achieves a reduction in porosity and an enhancement in grain size and precipitated phase distribution by the coupling of mechanical force field and ultrasonic energy field. Consequently, the mechanical properties of U-RE-WAAM samples are markedly superior, with a 32.8% increase in hardness and significant improvements in yield strength 81%, ultimate tensile strength 41%, and elongation 38.9%.