Effect of post-welding heat treatment on mechanical and microstructural properties of friction stir welded dissimilar magnesium alloys

Abstract

Magnesium (Mg) alloys have undergone a huge exploration to expand their applications because of their exceptional unique characteristics and their status as one of the lightest metals. Friction stir welding (FSW) is a well-known welding practice for Mg alloys. Heat treatment can enhance the weld joint's physical properties and performance. In the current work, FSW joint of AZ31 and AZ61 Mg alloys were heat treated at 260 °C for 15 min. It has been examined how post-weld heat treatment (PWHT) affects the microstructure and mechanical characteristics of AZ31-AZ61 Mg alloy FSW joints. PWHT has been found to have a remarkable impact on the weld joint. The weld's stirring zone yielded noticeably coarser grains. After heat treatment, the joint's elongation improved by around 39%. After PWHT, the stir zone showed the highest microhardness 69 Hv (reduced by about 11.87%). The impact toughness of the FSW joint was reduced after PWHT by about 6%.