Wire-arc additive manufacturing of Mg-Gd-Y-Zn-Zr alloy fabricated by cold metal transfer heat source: Processing, microstructure, and mechanical properties

Abstract

With the development of aerospace, Mg-Gd-Y-Zn-Zr alloy as a high-performance light alloy has attracted much attention. In this paper, the Mg-8.8Gd-3.9Y-0.85Zn-0.45Zr (wt%, GWZ941) alloy single-pass multilayer components fabricated by cold metal transfer wire and arc additive manufacturing (CMT-WAAM) in CMT mode, CMT-P mode and CMT-Advance mode. Studying the effects of the three CMT characteristics on voltage and current waveforms and metal transfer behaviors of the deposition processes for the GWZ941 alloy. The macro morphology, defect distribution, microstructure, and mechanical properties of the three as-deposited samples were compared. The GWZ941 alloy deposit fabricated by CMT-WAAM exhibits a uniform equiaxed grain structure whose average grain size of the three samples was 11.9 μm, 13.9 μm, and 7.9 μm, with the porosity less than 0.01%. The UTS and EL of the three GWZ941 alloy samples were 257 ± 4 MPa and 7.5 ± 1%, 230 ± 8 MPa and 3.5 ± 1%, 253 ± 2 MPa and 7.0 ± 0.3%, respectively. In the presence of oxide particles in the GWZ941 alloy formed by CMT-WAAM, the oxide content is less than 0.08%, which is the main influencing factor for the reduced strength and plasticity of the GWZ941 alloy.

Keywords

• Additive manufacturing
• Mg-Gd-Y-Zn-Zr alloy
• Microstructure
• Mechanical properties