Effect of Tungsten Inert Gas Welding Parameters on Hot Crack Sensitivity of Cast Magnesium Alloy

Magnesium alloys play important role in weight loss because of its high specific strength, most of magnesium alloy components are casting. Magnesium alloys have high hot crack sensitivity during casting and welding. Tungsten inert gas (TIG) welding parameters have great effects on hot crack sensitivity, which is important for welding and repairing alloys. However, few studies have been conducted in this regard. In this study, cracks in cast magnesium alloy AZ91D during TIG welding are examined and confirmed to be hot cracks. Different restraint and radiating conditions caused by structural affect the initiation and morphology of the hot cracks. The effect of TIG welding process parameters on thermal crack susceptibility was studied by Houldcroft crack test. Results reveal that welding parameters would significantly affect the crack length of the Houldcroft crack test specimens. Welding current and welding speed have complex and interactive effects on crack susceptibility. The present study has good effect on the magnesium alloy welding process development.