Surface modification of laser‐ and shot‐peened 6082 aluminium alloy

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.

Laser shock peening without absorbent coating (LSPwC) effect on 3D surface topography and mechanical properties of 6082-T651 Al alloy

“…The theory of non-dimensional 3D surface parameters is detailed in Ref. [30], Furthermore, results obtained in our experiments are in accordance with the expectations after strain hardening of soft materials [3,11,15,16].…”

“…As a result, high compressive residual stresses are generated and confined to a shallow surface layer whilst balancing low-tensile residual stresses are spread deeper throughout the cross-section of the material [12], Enhancement of fatigue, corrosion, stress corrosion and wear resistance has already been proved for various types of materials, such as aluminium and titanium alloys and different types of steel [11][12][13][14][15][16][17][18]. In our recent publication [18], we investigated the effect of LSPwC treatment on corrosion behaviour on an AA6082 aluminium alloy in a 0.6 M NaCI solution.…”

Mechanical Properties Enhancement of High Reliability Metallic Materials by Laser Shock Processing

“…In addition to residual stresses fields, the possible modification of the surface properties by LSP treatments is recognized as haven a decisive importance on the in-service components behaviour face to crack initiation by either mechanical or chemical (corrosion) causes (see references [9][10][11]). Surface roughness, for example has been identified as having a significant influence on the degradation and fatigue behaviour of several critical components, especially due to corrosion and fretting fatigue [15][16].…”

“…The first type of results are of special interest from the point of view of assessing the mechanical resistance of LSP treated components (especially those designed for high fatigue life under cyclic load, while the latter are considered to be especially useful from the point of view of surface integrity preservation against corrosion processes [10] or surface modification purposes in certain types of high specificity applications (see, i.e, ref [11]).…”

Application of the eigenstrain approach to predict the residual stress distribution in laser shock peened AA7050-T7451 samples

“…As the shock waves propagate into the material, a value of stress greater than the Hugoniot Elastic Limit value (HEL or Shock Yield Strength) is reached and the material deforms plastically at the surface. This permanent deformation generates surface compressive residual stresses [6] which greatly improve the fatigue life of a component as well as its corrosion behaviour [7].…”