Solidification cracking of Mg welds has been reported frequently, but the crack susceptibility itself has not been studied much. In the present investigation the widely used Mg alloys AZ31, AZ61, AZ91 and ZK61 were selected for the study. The crack susceptibility was predicted based on the maximum │dT/d(fS)1/2│ up to (fS)1/2 = 0.99 as the crack susceptibility index (T: temperature; fS: fraction of solid). The predicted crack susceptibility decreased in the order of ZK61 > AZ31 > AZ61 > AZ91. Since no reported data were available for comparison with the prediction, the transverse motion weldability (TMW) test was conducted. The tested crack susceptibility decreased in the order of ZK61 > AZ31 > AZ61 > AZ91, thus verifying the prediction based on the index │dT/d(fS)1/2│. The present study demonstrated that the crack susceptibility index and the TMW test can be useful tools for studying solidification cracking of Mg welds.

中文翻译：

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镁合金凝固裂纹敏感性

镁焊缝凝固​​开裂的报道屡见不鲜，但对裂纹敏感性本身的研究却很少。在目前的调查中，广泛使用的镁合金 AZ31、AZ61、AZ91 和 ZK61 被选择用于研究。裂纹敏感性基于最大 │dT/d(fS)1/2│ 直到 (fS)1/2 = 0.99 作为裂纹敏感性指数（T：温度；fS：固体分数）进行预测。预测的裂纹敏感性以ZK61 > AZ31 > AZ61 > AZ91 的顺序降低。由于没有报告数据可用于与预测进行比较，因此进行了横向运动可焊性 (TMW) 测试。测试裂纹敏感性以ZK61 > AZ31 > AZ61 > AZ91 的顺序降低，从而验证了基于指数│dT/d(fS)1/2│的预测。