Microstructure Characterization of AZ91D Magnesium Alloy Weldment Using Tungsten Inert Arc Welding Method

Abstract

The problem during magnesium alloy welding is the key bottleneck of magnesium application in aerospace, aircraft, automotive and other industries. AZ91D magnesium welded joint is obtained using tungsten inert gas (TIG) welding method without filler materials and groove. The microstructure, morphology, composition and micro hardness distribution of welded joint are investigated using scanning electronic microscopy (SEM), EDAX and micro hardness experiment. The results show: (1) Well welded joint of AZ91D magnesium alloy using TIG welding method is obtained under the condition of welding current 152A, welding voltage 13.4V, welding velocity 6.5mm/s and 20L/min Argon shielding gas; (2) Microstructure of welded joint consisted of black matrix phase α-Mg, white eutectic α+Mg17Al12 and gray dendrite.