Effects of microstructural inhomogeneities and micro-defects on tensile and very high cycle fatigue behaviors of the friction stir welded ZK60 magnesium alloy joint

Abstract The effects of microstructural inhomogeneities and micro-defects on tensile and very high cycle fatigue behaviors of a friction stir welded joint of ZK60 magnesium alloy have been investigated. The transitional zone between thermo-mechanically affected zone and heat affected zone on advancing side is prone to tensile fracture. With increasing of fatigue life, fatigue fractures transfer from the weak zone of static mechanical properties to the welding nugget zone, where softening effects of welding heat input govern fatigue failure at lower fatigue life and the porous micro-defects govern that at higher fatigue life.