Microstructure and mechanical properties of 2219 aluminum alloy fabricated by double-electrode gas metal arc additive manufacturing

Abstract

The present study focuses on the fabrication of 2219 aluminum alloy components using double-electrode gas metal arc (DE-GMA) based additive manufacturing (AM) capable of reducing deposition heat input while maintaining high deposition rates, and how the microstructure and mechanical properties of as-built parts are affected by the bypass current ratio which is a key factor that determines the heat input to deposited layers in DE-GMA based AM. The bypass current ratios with 0%, 50 %, 70 %, and 90 % were employed to deposit thin-walled parts. As the bypass current ratio increases, the equiaxed dendrite size in the top region decreases, cellular grains in the strip area disappear gradually, and equiaxed grains in the inner-layer area are slowly transformed into columnar grains. The bypass current exhibits little effect on microhardness and a significant influence on tensile properties. By changing the bypass current ratio from 0% to 70 %, the ultimate tensile strengths and the elongations in the vertical as well as the horizontal directions increase by 9.71 Mpa, 18.89 Mpa, 4.17 %, and 5.74 %, respectively. No orientation dependence on the ultimate tensile strength can be observed. Extensive dimples at the fractures show typical ductile fracture characteristics.