2004 Volume 45 Issue 2 Pages 419-422
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.