Mechanical and corrosion properties of rheocast and low-pressure cast A356-T6 alloy

In this study, the mechanical and corrosion behavior of rheocast and low-pressure cast A356-T6 alloy were examined and compared with each other. Tensile, impact and high-cycle fatigue tests were conducted to characterizing the mechanical behavior. For the study of general corrosion and stress corrosion cracking behavior of A356-T6 alloy, polarization, potentiostatic and in situ slow strain rate tests were performed on both products of A356-T6 alloy in a 3.5% NaCl solution. It was found that the mechanical and corrosion behaviors, as well as the microstructural features, of A356-T6 alloy were substantially affected by different processing routes. The tensile elongation and the impact energy values of A356-T6 were, e.g., greatly improved with rheocasting process. The resistance to general corrosion and stress corrosion cracking was also improved with rheocasting process. This study strongly suggests that the microstructural features, including the volume fraction and the shape of eutectic Si particles, are largely responsible for the variation in the mechanical and corrosion properties of A356-T6 alloy with different processing routes. (C) 2004 Elsevier B.V. All rights reserved.