Relationship between Shot Peening Surface Strain Layer and Fatigue Strength of High-Strength Alluminium Alloy

The relation of the fatigue behaviour to the residual stress and plastically deformed microstructure inthe surface strain layer of highstrength aluminium alloys is investigated.It is shown that the stress andmicrostructure strengthenings are two factors improving the fatigue behaviour,moreover,the microstructurestrengthening factor plays a main roleregion of S-N curve,but the main contribution to the fatiguebehaviour near the fatigue limit is made by the stress strengthening factor.There exists an optimum residualstress field induced by shot peening for a highstrength aluminium alloy,and the maximum compressiveresidual stress in the field is （σr）p≈σσ.