Corrosion and anodizing behaviour of friction stir weldment of AA2198- T851 Al-Cu-Li alloy

Abstract

Anodizing behaviour of AA2198-T851 friction stir weldment and the corrosion behaviour of unpolished and polished weldments of the alloy have been investigated. Electrochemical and microscopic techniques were employed in the study. The results revealed that the manufacturing-process induced near-surface deformed layer significantly affected the corrosion behaviour of the weldment. Thus, the corrosion behaviour of the weldment in the polished condition (which is the common practice) was different from that of the unpolished one due to the presence of near-surface deformed layer. Anodizing as a corrosion protection method for the weldment caused the formation of pronounced non-uniform oxide layer thicknesses across the weld zones. This was because the weldment oxidized at a higher rate compared with the parent material (PM) due to an increased proportion of Li in solid solution in the stir zone of the weldment.