Surface modification of laser‐ and shot‐peened 6082 aluminium alloy: Laser peening effect to pitting corrosion

Abstract

Purpose

The purpose of this paper is to investigate the effect of shock waves and strain hardening effect of laser and shot peening on precipitation‐hardened aluminium alloy AA 6082‐T651.

Design/methodology/approach

The hardened layer was evaluated by means of surface integrity with optical microscopy, scanning electron microscope (SEM), energy dispersive spectroscopy, analysis of microhardness and residual stress profiles. Corrosion anodic polarization tests in a 3.5 per cent NaCl water solution were carried out to express a pitting potential and the degree of pitting attack, which was verified on SEM and with 3D metrology.

Findings

Research results indicated significant differences between two treatment techniques which had an important influence on the final condition of the surface layer. Potentiodynamic polarization tests inferred that laser peening enabled shift of the pitting potential to more positive values, which ensures higher corrosion resistance.

Originality/value

Results confirmed that the higher corrosion resistance of the laser‐peened specimens against pitting corrosion depends on the modification of the surface, due to ablation during plasma generation. Despite increased surface roughness, laser‐peened specimen exhibits beneficial increase of the pitting/breakdown potential and in reduction of pitting attack degree at the specimen surface.

Citation

Trdan, U., Žagar, S., Grum, J. and Luis Ocan˜a, J. (2011), "Surface modification of laser‐ and shot‐peened 6082 aluminium alloy: Laser peening effect to pitting corrosion", International Journal of Structural Integrity, Vol. 2 No. 1, pp. 9-21. https://doi.org/10.1108/17579861111108572