Effects of Interpass Cooling on Material Properties of Wire Arc Additive Manufactured Al-6.3Mg Alloy

In this study, an aluminum (Al)-6.3 magnesium (Mg) alloy was fabricated using wire arc additive manufacturing (WAAM), and adopting the cold metal transfer advanced process, with the thermal history of the deposits controlled by the interpass temperature, and the changes in the material properties of the deposits were studied. The effects of various interpass temperatures on the deposition surface oxidation, geometry, pores, microstructure, and mechanical properties of the fabricated part were investigated. The results showed that with the decrease of interpass temperature, degree of surface oxidation decreases, width of deposits decreases, height of layer increases, porosity decreases, dendrites were eliminated, grains were refined, segregation of the harmful precipitated phases [beta(Mg2Al3) and (FeMn)Al-6] reduces, and the microstructure is homogenized. In addition, thermal history played a decisive role in improving the performance of the WAAM Al-Mg alloy. Reducing the interpass temperature effectively improved the mechanical properties and reduced the difference between the horizontal and vertical properties of the deposits. The optimal mechanical properties included a tensile strength of 321 MPa, yield strength of 232 MPa, and elongation of 28%.