Additive manufacturing of high performance AZ31 magnesium alloy with full equiaxed grains: Microstructure, mechanical property, and electromechanical corrosion performance

Abstract

• AZ31 alloy with full of equiaxed grains was obtained by GTAW-based additive manufacturing. • Relationship between the microstructure and properties of AMed AZ31 alloy were studied. • Comparison between the corrosion resistance of hot-rolled and AMed AZ31 alloy was conducted. Additive manufacturing (AM) technology has drawn tremendous attention in producing lightweight and complex metallic components. In this work, a thin wall of AZ31 Mg alloy with fine equiaxed grains was fabricated via gas tungsten arc-based wire arc additive manufacturing (WAAM-GTA) technology. The grain structure, dislocation, and texture of the hot-rolled and WAAM-GTA AZ31 samples were analyzed by EBSD, while the matrix and dispersed phases were characterized by EDS and X-ray diffraction. The 3D porosity of samples was examined quantitatively by an X-ray computed tomography (XCT). The results show that dominated equiaxed α-Mg grain structure was obtained together with negligible precipitated phase. The mechanical properties of WAAM-GTA AZ31 were superior to their cast counterparts and close to those of wrought AZ31, and their correlation to microstructure and defects were explored. Moreover, the WAAM-GTA AZ31 showed excellent electromechanical corrosion performance in 3.5 % NaCl solution as compared to the hot-rolled AZ31 plate. The WAAM-GTA technology therefore offers new routes to fabricate AZ31 Mg components with equiaxed grain structure, as well as favorable mechanical properties and electromechanical corrosion performance.