Formation of Stress Cracking in an AZ61 Magnesium Alloy Joint

Cracking is a major reason for the failure of magnesium alloy joint. It would be often caused by stress concentration. In this study, a double side gas tungsten arc (GTA) welding of AZ61 magnesium alloy plate and finite element method (FEM) were conducted to investigate the effect of partial melting on the formation of stress cracking in the welded joint. The surface microstructure of cracking formed in the welded seam was characterized by scanning electron microscopy, and software, Sysweld, was used to simulate the thermal history and residual stresses distribution of the weldment. The results indicated that under the influence of stress concentration, the fusion of low melting point eutectic compound β-Mg 17 Al 12 along grain boundaries induced the cracking in the welded seam. This study has theoretical guiding significance to prevent the formation of stress cracking caused by fusion of eutectic compound β-Mg17Al12 , which is especially critical for the manufacturing of magnesium alloy welded components.