Effects of Pouring and Mold Temperatures on the Fluidity and Hot Tearing Susceptibility of Al–3.5Si–0.5Mg–0.4Cu Alloy

The effects of pouring and mold temperatures on the fluidity and hot tearing susceptibility (HTS) of Al–3.5Si–0.5Mg–0.4Cu alloy were investigated by the spiral mold test and the constrained-rod casting mold test, respectively. Optical microscope (OM) and scanning electron microscope (SEM) were carried out for microstructure observation. The results showed that the flow length ( L f ) of Al–3.5Si–0.5Mg–0.4Cu alloy increased with increasing pouring temperature ( T ) and mold temperature ( T 0 ). Moreover, the functional relationship between the fluidity and casting parameters was obtained by fitting the fluidity data as: L_f = 60.9 + 1082.4[Δ T/T - T_0] . The hot tearing mechanism was analyzed by observing the microstructure of the hot crack, and the HTS of the alloy with the mold and pouring temperatures was discussed in detail. According to the research, to achieve a lower hot tearing susceptibility under better fluidity, the suggested pouring and mold temperatures are 740 °C and 200 °C, respectively.