Effects of ablative and non-ablative laser shock peening on AA7075-T651 corrosion and fatigue performance

A. G. Sanchez, M. Leering, D. Glaser, D. Furfari, M. E. Fitzpatrick, J. A. Wharton, P. A.S. Reed

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1 Citation (Scopus)
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Abstract

The fatigue performance from pre-corroded pits was studied in laser-shock-peened AA7075-T651 with and without a protective ablation-layer. Surface and microstructural characterisation showed laser-shock-peening generated residual stresses up to −400MPa, limited hardness and moderate surface roughness increase. The laser-shock-peened specimens were exposed to 3.5 wt-% sodium chloride solution for different levels of galvanostatic control. The compressive residual stresses did not significantly affect corrosion behaviour, or corrosion pit morphology. Laser-shock-peening-induced surface roughness had the most detrimental impact on corrosion performance. Fatigue testing of pre-corroded AA7075-T651 showed pits act as stress concentrations. Cracks initiated shortly after dynamic loading, reducing fatigue life by 50%. Laser-shock-peening increased fatigue life by 400% compared to corroded-untreated AA7075-T651, due to residual stresses effectively counteracting stress concentrations produced by pits. Highlights Pre-corroded laser-peened (LSP and LSPwC) AA7075-T651 fatigue performance is investigated. XRD and incremental hole drilling show deeper compressive residual stresses for LSPwC compared to LSP. Electrochemical tests show no significant changes in corrosion behaviour after laser peening. Fatigue testing and fractography show compressive residual stresses effectively counteract stress concentrations at pits.

Original languageEnglish
Pages (from-to)1015-1034
Number of pages20
JournalMaterials Science and Technology (United Kingdom)
Volume37
Issue number12
Early online date19 Sep 2021
DOIs
Publication statusPublished - 2021

Bibliographical note

This is an Open Access article distributed under the terms of the
Creative Commons Attribution License
(http://creativecommons.org/licenses/by/4.0/), which permits
unrestricted use, distribution, and reproduction in any medium, provided
the original work is properly cited

Funder

Engineering and Physical Sciences Research Council (EPSRC), UK [grant number EP/N509747/1].

Keywords

  • ablation
  • aluminium alloy
  • compressive residual stress
  • corrosion performance
  • fatigue performance
  • Laser shock peening
  • material characterisation
  • pre-corroded

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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