Laser surface treatment of aluminium alloys for enhanced pitting resistance

High-strength aluminium alloys are frequently susceptible to localised corrosion. In this paper, improvement of pitting corrosion resistance of 2014-T6 aluminium alloy has been investigated by the technique of surface treatment with both CO2 and excimer lasers. Laser process conditions for obtaining pore-free and crack-free melted layers are defined. The surface morphology and microstructure produced from both treatments were analysed by optical microscopy, SEM, EΡΜΑ and TEM. It was found that for CO2 lasers, second phase particles were dissolved and re-formed as fine dispersed particles in the melted layer and that both macrosegregation and microsegregation were produced during solidification. A thin melted layer can be produced by excimer laser treatment without cracks and porosity and the segregation was minimised. Measurements of the corrosion resistance in de-aerated 1M NaCl solution revealed a favourable influence on the pitting behaviour after both laser treatments.High-strength aluminium alloys are frequently susceptible to localised corrosion. In this paper, improvement of pitting corrosion resistance of 2014-T6 aluminium alloy has been investigated by the technique of surface treatment with both CO2 and excimer lasers. Laser process conditions for obtaining pore-free and crack-free melted layers are defined. The surface morphology and microstructure produced from both treatments were analysed by optical microscopy, SEM, EΡΜΑ and TEM. It was found that for CO2 lasers, second phase particles were dissolved and re-formed as fine dispersed particles in the melted layer and that both macrosegregation and microsegregation were produced during solidification. A thin melted layer can be produced by excimer laser treatment without cracks and porosity and the segregation was minimised. Measurements of the corrosion resistance in de-aerated 1M NaCl solution revealed a favourable influence on the pitting behaviour after both laser treatments.