Characterization on electron beam welds and parameters for AZ31B-F extrusive plates

Recent years have seen a renewal of interest in magnesium alloys because of the extensive applications in the industry of 3C, aerospace and traffic. However, applications of magnesium alloys are still restricted by their poor formability. This can be improved by dividing the shape-complicated work piece into several easily-made parts and then combining into one. There are various kinds of defects in the weld under the interaction of AZ31B properties and welding conditions. These defects will produce obvious stress concentration and serious material damage. In this study, a home-made 11 mm-thick AZ31B extrusive plate was used. By operating and comparing the changeable parameters of electron beam welding (EBW), the condition was optimized as 100 mA, 50 kV, 60.6 mm/s and focus position at bottom. Seventy-eight percent and 91% of the base material strength were obtained by stress and non-stress concentration weldments, respectively. Meanwhile, the harmful influence of SC and grain coarsening reached at least 13% and 9%, respectively. With other worse parameters, the strength of AZ31B weldments were reduced by undercut, root concavity, cavities and heat-affected zone (HAZ).