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.
Reference:
Sanchez, A., You, C., Leering, M., Glaser, D., Furfari, D., Fitzpatrick, M., Wharton, J. & Reed, P. et al. 2020. Effects of laser shock peening on the mechanisms of fatigue short crack initiation and propagation of AA7075-T651. International Journal of Fatigue, 143. http://hdl.handle.net/10204/12019
Sanchez, A., You, C., Leering, M., Glaser, D., Furfari, D., Fitzpatrick, M., ... Reed, P. (2020). Effects of laser shock peening on the mechanisms of fatigue short crack initiation and propagation of AA7075-T651. International Journal of Fatigue, 143, http://hdl.handle.net/10204/12019
Sanchez, AG, C You, M Leering, Daniel Glaser, D Furfari, ME Fitzpatrick, J Wharton, and PAS Reed "Effects of laser shock peening on the mechanisms of fatigue short crack initiation and propagation of AA7075-T651." International Journal of Fatigue, 143 (2020) http://hdl.handle.net/10204/12019
Sanchez A, You C, Leering M, Glaser D, Furfari D, Fitzpatrick M, et al. Effects of laser shock peening on the mechanisms of fatigue short crack initiation and propagation of AA7075-T651. International Journal of Fatigue, 143. 2020; http://hdl.handle.net/10204/12019.
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