Study on Mechanical, Microstructural and Corrosion Analysis of Wire Arc Additive Manufactured AZ31 Magnesium Alloy

Wire arc additive manufacturing (WAAM) offers significant potential for producing large-scale magnesium (Mg) alloy components, which are highly valuable for industries such as automotive and aerospace. This study explores the microstructure, mechanical properties, and corrosion performance of AZ31 magnesium alloy produced using the cold metal transfer (CMT)-WAAM process. Microstructural analysis reveals that the WAAM-fabricated AZ31 exhibits an equiaxed grain structure with intergranular precipitates, influenced by welding parameters and cooling rates. The study also examines the impact of process parameters on bead geometry and microstructure, emphasizing the relationship between wire feed rate, travel speed, and bead characteristics. Tensile samples were extracted from the base plate at orientations of 0°, 45°, and 90°. The average ultimate tensile strength (UTS) and percentage elongation for the WAAM-processed AZ31 magnesium alloy ranged from 289 to 301 MPa and 19 to 22%, respectively, depending on the orientation. WAAM-fabricated AZ31 which is superior compared to conventional cast and wrought alloys, attributed to fine grain structure and evenly distribution of precipitates such as α-Mg and Mg₁₇Al₁₂. X-ray diffraction analysis and EDS validate the presence of α-Mg, and Mg₁₇Al₁₂ phases in the fabricated alloy. Corrosion tests revealed that the formation of a protective film significantly enhanced the corrosion resistance of WAAM-fabricated samples compared to the wrought alloy. Electrochemical testing showed superior corrosion resistance in the bottom region of the thin wall, with a corrosion rate of approximately 12 mm/y, compared to the top region, which had a corrosion rate of about 16 mm/y. This improved performance was attributed to the refined grain structure and the presence of a protective oxide film.