The paper provides a thorough analysis of a surface layer prior to and after Laser Shock Processing under different parameter conditions. Optimum conditions were determined using a factorial design aided with an analysis of variance (ANOVA). As the first experimental factor, pulse density with 900 and 2500 pulse/cm² was chosen. The second factor was the type of material, i.e. aluminium alloys ENAW 6012 and ENAW 6082. Evaluation of different conditions of specimen treatment was made using three response variables, i.e. surface roughness, magnitude of residual stresses, and corrosion resistance given by pitting potential (Epitt). A thorough analysis of the modified surface layer was made with measurement of microhardness, and with images obtained in optical and electronic microscopy (SEM) and energy dispersion spectroscopy (EDS) to determine corrosion products around the pits formed after corrosion testing. The experiments confirmed characteristic influences of individual LSP parameters on properties of the treated material surfaces. ENAW 6012 aluminium alloy showed better corrosion resistance than ENAW 6082 alloy with lower pitting attack at its surface. Corrosion tests showed that a higher pulse density produces shifting of the pitting potential to more positive values, which ensures higher corrosion resistance from the viewpoint of preserving a passive protecting film on the surface layer.

Date Published: 21 April 2009
PDF: 8 pages
Proc. SPIE 7131, XVII International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers, 713124 (21 April 2009); doi: 10.1117/12.816643

Published in SPIE Proceedings Vol. 7131:
XVII International Symposium on Gas Flow, Chemical Lasers, and High-Power Lasers
Rui Vilar; Olinda Conde; Marta Fajardo; Luís O. Silva; Margarida Pires; Andrei Utkin, Editor(s)