Non-thermally treated Al-Mg based alloy is looked forward to as potential material for automotive body parts due to its ductility. In this study, the influence of the amount of Si, Sr, Ti, and B added to Al-4.5Mg-1.0Mn based alloy on both hot tearing susceptibility and mechanical properties (0.2% proof stress and fracture elongation) was examined. Each alloy composition was used to produce an automotive rear suspension part called lower link arm by high pressure die casting. The susceptibility was evaluated by measuring the length of hot tearing in the lower link. Tensile test pieces were cut off from the bottom of the lower link. As a result, it was found that susceptibility could be suppressed by adding Si, Sr, Ti, and B to the base alloy. With increasing Si addition, fracture elongation decreased. In order to obtain alloy with low hot tearing susceptibility and fraction elongation over 10%, Si content should be less than 0.5% with the addition of 0.020±0.005% Sr, 0.008% Ti, and 0.016% B.
