Hot tearing behavior and mechanism of AXJ530 alloy under rotating magnetic field

In order to solve the issues concerning high hot tearing susceptibility (HTS) of Mg-Al-Ca series alloys, a rotating magnetic field (RMF) was applied during their solidification. The effect of RMF at different excitation current intensities (50 A, 100 A, and 150 A) on the solidification and hot tearing behavior of AXJ530 (Mg-5Al-3Ca-0.17Sr) alloy was investigated. The results indicated that the HTS of AXJ530 alloy decreased with the increase of excitation current intensity. This aspect can be attributed to significant grain refinement under the action of RMF, which improved the intergranular bonding and relieved the stress concentration. On the other hand, the stirring effect of the electromagnetic force on the melt could break up the developed dendrites and delay the dendrite coherence, as well as optimize the feeding channels and improve the feeding drive of the residual liquid at the end of solidification. Therefore, under the action of RMF, the hot tearing initiation of the alloy was suppressed and the feeding efficiency of the liquid was greatly improved, which led to a noticeable reduction of the HTS of the alloy. Moreover, no significant hot tearing was detected in castings at the excitation current parameters of 150 A and 10 Hz.