Hot Tearing Evaluation of Al-0.9Mg-0.7Si Aluminium-cast Alloy

This study aimed to evaluate the hot tearing susceptibility (HTS) of the Al-0.9Mg-0.7Si aluminium casting alloy, with a particular focus on how cooling rates and thermal stresses during solidification influence this phenomenon. To capture these parameters, the experiment employed the constrained rod casting (CRC) technique, which facilitated the real-time measurement of both cooling and force curves. Hot tearing was analysed across various casting configurations, incorporating different feeding mechanisms to assess their effect on tear resistance. The fracture surfaces resulting from hot tearing were examined in detail using scanning electron microscopy (SEM), providing insight into the microstructural characteristics at the tear sites. The results revealed that the Al-0.9Mg-0.7Si alloy exhibits an HTS value of 12, indicating moderate susceptibility under the tested conditions. Furthermore, the alloy displayed an average cooling rate of 7.95 °C/s and an average maximum load of 233.01 N, underscoring the significant impact of thermal gradients and induced stress on crack formation. These findings enhance the understanding of the factors governing hot tearing in aluminium alloys, with potential implications for alloy design and process optimisation aimed at reducing defects in cast aluminium products.