Surface modification of aluminium alloys with Laser Shock Processing

Abstract

An adequate residual stress variation and frequently also improved corrosion resistance of a material are key requirements for usability of numerous machine components in various applications. The aim of the investigation conducted was to determine optimum Laser Shock Processing (LSP) parameters for aluminium specimens in order to obtain the desired residual stress variation and improved corrosion resistance. LSP treatment was performed with a Q-switched Nd:YAG laser with a wavelength of 1064 nm. In order to statistically confirm the optimum process parameters, a factorial design was applied, in which the first experimental factor was pulse density, i.e. 900 and 2500 pulses/cm2, the second factor was the type of material used, i.e. aluminium alloys AlMgSiPb and AlSi1MgMn and the third factor was the direction of LSP surface sweep, i.e. longitudinal and transversal direction. The experiments made confirmed a characteristic influence of the first factor representing different pulse densities. An analysis of residual stresses confirmed that in processing with 2500 pulses/cm2 the highest compressive residual stresses were obtained. Potentiodynamic corrosion testing confirmed that the higher pulse density resulted in a stronger shift of pitting potential, which provided higher corrosion resistance. © 2011 Journal of Mechanical Engineering. All rights reserved.