The Effect of Heat Treating and Deformation by Rolling and Forging on the Mechanical Properties of the 4032-Type Alloy Prepared from Recycled Materials

Abstract

In the present work, the relationship between deformation, microstructure and mechanical properties of the Sr-modified 4032-type eutectic aluminum alloy was studied. The alloy was prepared from recycled materials, mainly from maritime and automotive 356 alloy scrap samples. Solubilizing heat treatment was carried out at a temperature of 450 °C with a holding time of 8 h. Finally, different samples were subjected to rolling and forging processes at a temperature of 450 °C, thus achieving a reduction of 25% of the original thickness. As expected, the microstructure and properties changed significantly due to the deformation processes, where an important factor was the change in the morphology of eutectic silicon, not only produced by the application of deformation, but also on the effect of adding strontium as a modifying agent. The samples were characterized by optical microscopy and scanning electron microscopy, where it was possible to observe not only the effect of strontium on the morphology of eutectic silicon but also the effect of the heat treatment performed. The tensile tests showed that there was indeed a notable increase in the ultimate tensile stress, yield strength, and resistance to fracture, while initial hardness also considerably increased. Finally, the fracture analysis showed that, after thermal treatment and deformation, all the samples analyzed presented a fracture within the ductile regime. It was shown that the combination of deformation and the addition of strontium led to improved globulization of the eutectic silicon.