Extrusion weld seam and mechanical properties of high-strength Mg-Gd-Y-Zn-Mn alloy hollow profile fabricated via porthole die extrusion.

A high-strength Mg-8.8Gd-3.8Y-1.0Zn-0.7Mn (wt%) alloy hollow profile with complex cross-section was successfully fabricated through porthole die extrusion, and its weld seam was analyzed for microstructure and element distribution to investigate the impact of solid-state bonding. The weld seam displayed a homogeneous magnesium grain structure and a precipitation-free zone. The diffusion behavior of alloying elements during solid-state bonding significantly affected the microstructure of the weld seam, with Gd and Y atoms diffusing towards the outside of the weld region. The hollow profile exhibited favorable mechanical properties, with an ultimate tensile strength (UTS) of 470 MPa, a tensile yield strength (TYS) of 309 MPa, and an elongation (EL) of 7.4%, and showed a minor negative effect from the weld seam. • High-strength Mg-Gd-Y-Zn-Mn alloy hollow profiles showed a favorable metallurgical bond in the weld seam with a homogeneous magnesium grain structure and no microvoids. • Alloying element diffusion influenced the weld seam microstructure, resulting in lower concentrations of Gd and Y in the weld region, while Zn and Mn showed a more uniform distribution. • The presence of the weld seam had minimal impact on the overall mechanical properties of the hollow profiles, which retained superior mechanical performance. [ABSTRACT FROM AUTHOR]