In order to improve the fatigue performance of Ti–6Al–4V (TC4) titanium alloy

the effects of three surface strengthening methods

namely laser shock (LSP)

shot peening (SP) and their composite strengthening (LSP+SP)

on the high-cycle fatigue performance of TC4 titanium alloy were investigated; The residual stress distribution of the surface layer of the specimen after the three strengthening processes was analyzed by X-ray diffraction method

and the microhardness was determined by microhardness tester. The fatigue limit of TC4 titanium alloy was tested by X-ray diffraction method

and the microhardness was determined by microhardness tester. Under the condition of high-cycle fatigue loading at 20 ℃

the fatigue limit was tested based on the up and down method

and the Goodman curves and formula for the fatigue life design of TC4 titanium alloy and the P-Goodman curves based on reliability were established. Compared with the unreinforced smooth specimens

the fatigue limits of LSP

SP

and LSP+SP specimens are enhanced by 18.2%

10.1%

and 26.6%

respectively. Combined with the critical distance theory

the Goodman model considering the effects of residual stress and average stress is obtained

and the error is no more than 5% when compared with the data of composite-reinforced high-cycle fatigue tests; Based on the probability distribution function

the P-Goodman curves under different degrees of reliability for different reinforcement processes are determined. The specimens with composite reinforcement process are less prone to fatigue damage under the same applied load conditions.