Fig. 1. (a) Region and path of LP; (b) specimen surface after LP

Fig. 2. Schematic of electrochemical hydrogen charging

Fig. 3. Test positions of residual stress and microhardness

Fig. 4. Tensile specimen and peening scheme

Fig. 5. Surface morphology of tensile specimen after LP

Fig. 6. Test of surface residual stress

Fig. 7. Test of surface microhardness

Fig. 8. Force-displacement curves at room temperature

Fig. 9. Fracture macro-morphologies of different specimens. (a) Matrix; (b) specimen with LP and without hydrogen charging; (c) specimen without LP and hydrogen charging; (d) specimen with LP and hydrogen charging

Fig. 10. Fracture micro-morphologies of different specimens. (a) Matrix; (b) specimen with LP and without hydrogen charging;(c) specimen without LP and hydrogen charging; (d) specimen with LP and hydrogen charging

Fig. 11. Schematic of hydrogen embrittlement resistance of TC4 titanium alloys strengthened by LP. (a) Before hydrogen charging; (b) after hydrogen charging; (c) slow stretch; (d) hydrogen-induced crack nucleation