Fig. 1. Size of specimen

Fig. 2. Experimental set-up for laser shock processing

Fig. 3. Laser impulse sequence

Fig. 4. Experimental machine for fatigue test

Fig. 5. Surface morphology and profile curves of LSP sample. (a) Macro morphology of sample surface; (b) 3D image of un-LSP region; (c) 3D image of LSP region; (d) profile curves of un-LSP region; (e) profile curves of LSP region

Fig. 6. Residual stress distribution along sample surface

Fig. 7. Macro fatigue fracture of LSP sample

Fig. 8. Morphology of fatigue crack initiation region. (a) Sample without LSP; (b) sample with LSP

Fig. 9. Diagram of effect of compressive residual stress on crack initiation

Fig. 10. Morphology of crack growth zone. (a) Sample without LSP; (b) sample with LSP; (c) enlarged image of Zw region; (d) enlarged image of Zp region

Fig. 11. Morphology of abrupt fracture zone. (a) Sample without LSP; (b) sample with LSP; (c) enlarged image of Zw region; (d) enlarged image of Zp region

Fig. 12. Crack length versus the loading cycle number