Microstructure and tensile properties of friction stir and gas tungsten arc welded AZ91D magnesium alloy joints

摘要

Influence of a fusion welding process namely gas tungsten (GTAW) and a solid state friction stir welding (FSW) on the microstructural changes and tensile strength variation of cast magnesium alloy joints were investigated and the results are compared. Of the two joints fabricated, FSW joint showed superior tensile properties compared to GTAW joint due to the difference in microstructural gradient across the weld cross section. Wider partially melted zone and heat affected zone was observed in GTAW joint due to the high heat input nature process compared to narrow heat affected zone in FSW joint. Microhardness measurement indicates that, the weld metal is overmatched compared to the base metal irrespective of welding process used.