Corrosion protection of AA2024-T351 friction stir welds by laser surface melting with Excimer laser

Abstract

The effect of an Excimer laser treatment on the corrosion resistance of friction stir welds in AA2024-T351 has been studied by means of electrochemical techniques and immersion tests. The results show a decrease in anodic and cathodic reactivity in the weld region after the laser treatment, achieved due to the formation of a 3-5 μm thick corrosion resistant layer. Immersion tests in 0·1M NaCl confirm that the presence of the treatment decreases the severity of corrosion attack. However they also show that, if the laser layer is damaged by a scratch, corrosion occurs preferentially in the scratch area. Delamination of the laser treated layer can also occur as a consequence of corrosion propagation during the exposure of laser treated samples.