Fatigue of Welded Magnesium Alloy Joints

Abstract

Fatigue tests were carried out on welded joints of commercial AZ31 alloy and AZ61 alloy in air as welded surface condition. Alloys were extruded or rolled to a plate shape. Pairs of the same type of alloy plates were butt-welded by tungsten inert gas (TIG) welding or friction stir welding (FSW). All welded joints except FSW-ed AZ61 have joint efficiency of around 90% for static tensile strength. Extruded AZ31 alloy joints by TIG or FSW showed fatigue joint efficiency of about 80%. However, fatigue joint efficiencies for other joints were at around 60%. Fracture surfaces showed brittle fatigue crack propagation; moreover, the directions of crack propagation were influenced remarkably by the microstructures.