A laser shock peening (LSP) treatment was performed on AA7075-T651 for maximum fatigue improvement. Surface and microstructural characterisation techniques (micro-hardness, SEM-EBSD, contact-profilometry) showed LSP surface modification was limited, and LSP generated deep compressive residual stresses above −300 MPa. Fatigue testing showed a two-order magnitude increase in overall life, due to the mechanism of crack initiation changing from surface second-phase particles to subsurface crack initiation dependent on the local stress field. Modelling highlights the sensitive balance between surface roughness (including LSP-induced pits) and residual stress on the micro-mechanism of crack initiation, and how this can be used to maximise fatigue life extension.
Bibliographical noteNOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Fatigue. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Fatigue, 143 (2021)] DOI: 10.1016/j.ijfatigue.2020.106025
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FunderEngineering and Physical Sciences Research Council (EPSRC), UK (Grant EP/N509747/1 )
- Aluminium alloys
- Fatigue initiation
- Surface flaws
ASJC Scopus subject areas
- Modelling and Simulation
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
- Industrial and Manufacturing Engineering