The Role of Friction Stir Welding on the Microstructure and Mechanical Properties of AZ31B-H24 Mg alloy

In this study, an attempt was made to join AZ31B magnesium alloy by friction stir welding (FSW) process. A single tool with cylindrical screw threaded pin was used to investigate the effect of welding parameters on microstructure and mechanical properties of stir zone (SZ). Several welds were made at different rotational (omega) and traverse (upsilon) speeds, while the omega/upsilon ratios were kept constant. The optical and scanning electron microscopy were used to study the variation of microstructure across the welds. Moreover, micro-hardness and tensile tests were carried out to evaluate the mechanical properties of joints. It was found that. plays more significant role on the resulted grain structure than., and at a constant omega/upsilon ratio, decreasing rotational speed decreased the size of grains, and hence, improved the hardness value and the tensile strength of the SZ.