Effect of surface damage on the corrosion resistance of 6005A aluminum alloy in simulated seawater

A 6005A aluminum alloy was produced by an actual surface with less defects, multiple defect samples, and as-ground samples for the purpose of investigating the effect of aluminum alloy surface damage on corrosion resistance and its corrosion electrochemical behavior in seawater. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were employed in order to characterize the surface states of the 6005A aluminum alloy. The results show that the surface defects caused by aluminum alloy products consist mainly of scratches. With the increase of surface defects, an obvious increase in Ra is observed, and Ra could quantitatively describe the severity of surface damage. In simulated seawater, the 6005A aluminum alloy undergoes comprehensive corrosion and pitting; thereby, corrosion resistance deteriorates as the amount of defects increases. Electrochemical test results show that the larger the number of surface defects is, the greater are the roughness and lower corrosion potential. Additionally, the greater the corrosion current density is, the worse is the corrosion resistance. A 6005A aluminum alloy that has suffered surface damage and whose corrosion resistance was affected due to seawater can cause the following:the more surface defects are, the greater is the roughness and surface film damage; thereby, the plastic deformation of the surface becomes more serious. The protective layer of the oxide filmis reduced, and the substrate has a higher corrosion rate. The passive film for the samples with less defects is more compact and uniform and could protect the substrate, while effectively reducing further corrosion.