Effect of pitting corrosion on high cycle fatigue behaviour of anodized cast AlSi7Mg alloy

This study investigates the effect of pitting corrosion on the mechanical performance of anodized, cast AlSi7Mg Aluminium alloy. Tensile tests and high cycle fatigue measurements are carried out on anodized specimens after exposure to a neutral salt spray atmosphere for various periods of time. X-ray microtomography analyses and fracture surface inspections are performed on as-anodized and corroded specimens to investigate the correlation between corrosion pit dimensions and fatigue life. It is concluded that after pit nucleation the pit volume increases with the exposure time to salt spray tests with an associated detrimental effect on fatigue life. In addition, after 1000 h of exposure to a chloride-rich environment, the main cause of fatigue crack initiation changes from casting defects, which are clearly visible at 0 h and 480 h, to corrosion pits. The results will enable a future tailored design of fatigue resistant components based on cast AlSi7Mg alloy subjected to anodizing.