Effect of pre-welding heat treatment on GTAW crack sensitivity of cast AZ91D

Cast magnesium alloys are widely used but prone to welding cracks due to low-melting eutectics. This study investigates hot cracking sensitivity in AZ91D magnesium alloy and the effects of pre-weld heat treatment. By analyzing β-phase content and grain size, the results show that solution treatment reduces β-phase content, thereby decreasing liquation and crack length. However, the increased grain size resulting from solution treatment may increase crack length. Aging treatment has minimal impact on grain size or liquation, offering limited influence on crack sensitivity. The study proposes microstructure modification as an effective method to improve hot crack resistance in AZ91D, enhancing its weldability for industrial applications.