A method for predicting hot tearing during alloy solidification and its application in AZ91D magnesium alloy

Hot tearing is a critical defect in casting, welding, and additive manufacturing. In this work, we introduced a tendency index of hot tearing, ε̇ḟs (the ratio of strain rate ε̇ to the rate of change of fraction of solid ḟs), and a new criterion for hot tearing propagation, ε̇ḟscritical<ε̇ḟs. To evaluate and apply our model, the hot tearing in actual AZ91D alloy castings were calculated. Experimental results are consistent with numerical predictions using the index and criterion we proposed. Mechanisms of hot tearing formation are described, factors influencing hot tearing propagation are discussed, and practical methods for mold design and process optimization in minimizing hot tearing formation are suggested.