Comparative study of metallic foil friction stir welded and conventional friction stir welded AZ61 Mg alloy butt joints: Biomedical and engineering applications

Abstract

Metallic Foil Friction Stir Welding (MFFSW) was newly developed from the Friction Stir Welding (FSW) technique. Magnesium (Mg) alloys were the most trending alloys in the aerospace, automobile, and biomedical industries. This study aims to investigate the variation in mechanical, corrosive, microstructural, and fractographic properties of MFFSW as a process innovation when compared with FSW. The metallic foil of pure manganese (Mn) with a thickness of 500 μm was inserted between two AZ61 Mg alloys. The tensile strength, impact strength, and hardness were noted as mechanical properties of the output. Potentiodynamic corrosion tests were performed to reveal the corrosion properties. An optical microscope was used to examine a distinct transverse section of the weld. Fractography tests with scanning electron microscopic analysis were conducted on destructive tensile specimens. The ultimate tensile strength, impact energy, yield strength, and microhardness increased to 16%, 32%, 12%, and 19.17%, respectively, compared to FSW. MMFSW shows a lower elongation of up to 33% than FSW. MMFSW (9.61 mm/A) shows a lower corrosion rate than FSW (11.02 mm/A), which employs improved corrosion properties. Optical microscopy images of the stir zone in both MFFSW and FSW revealed that adding a Mn alloying element improved grain growth uniformity and eliminated unexpected grain growth patterns. Hence, the experiment’s conclusion shows that MFFSW has the edge over FSW for mechanical and corrosion properties. Thus, the Mn strip improves the properties of MFFSW.