Effect of gas metal arc welding on microstructure, microtexture, and mechanical properties of a new type Al-Mg-Er-Zr alloy

A new type of Al-Mg-Er-Zr alloy was welded by a gas metal arc welding (GMAW) process. The effect of GMAW welding on the microstructure, microtexture, and mechanical properties was investigated and compared with the base material (BM). The results show that GMAW welding leads to a change in the grain shape, grain orientations, phase composition, microtexture, microhardness, and tensile properties. The weld metal (WM) exhibits coarse grains, high proportion of high angle grain boundaries (HAGBs), and low intensities of random textures compared with the BM. In addition, the recrystallization occurs in the HAZ due to the welding heat effect; grains and secondary phases are coarsened compared with the BM. The texture evolution in the HAZ exhibits the disappearance of the deformation textures, along with the transformation and competitive growth of P, R, and Cube recrystallization textures. The average ultimate tensile strength (UTS) of the GMAW joints is 280.7 MPa, and the lowest hardness of 75.2 HV is located in the WM. Compared to the BM, the welded joints in the Al-Mg-Er-Zr alloy produce reduced microhardness and tensile properties. However, the strength coefficient of the welded joints reaches 0.75, together with the elongation index (EI) of 11.4%, implying GMAW welding for the Al-Mg-Er-Zr alloys achieves a good combination of strength and ductility.