Aluminum alloys are widely used in the automotive and aerospace industries due to their low density and very high specific strength, and high-pressure die casting (HPDC) allows us to mass-produce complex components despite porosity and microstructural heterogeneity. In this study, we examine the individual and combined effect of grain refinement (AlTi5B1), chemical modification (AlSr15), and T6 heat treatment on the microstructure, mechanical properties, and corrosion of ENAC 46000 alloy produced in cold-chamber HPDC. The material characteristics were assessed through hardness, tensile, fatigue, and corrosion testing as well as optical microscopy, SEM, and EDS measurements. The microstructural characteristics were found to be fine α-Al grains, and Sr modification transformed eutectic Si into a fibrous structure. T6 treatment dissolved coarse Al2Cu phases into fine coherent precipitates. T6 heat treatment was the primary strengthening process and produced an increase in hardness of 59% (to 143 HB) compared to non-T6 conditions, while the fatigue resistance was still excellent in the as-cast state (1.16 × 106 cycles). Moreover, the modified and T6-treated condition exhibited the lowest corrosion rate (15.3 × 10−3 mm/year). Therefore, because no single processing route is the best way to maximize all performance characteristics (as well as process efficiency), a multi-property evaluation should be performed to tailor treatment to the engineering service requirements.
Karayol et al. (Tue,) studied this question.