Water jet peening (WJP) is a mechanical surface strengthening process, which can improve the residual stress (RS) of the peened surface and then improve the fatigue life of components. In this paper, erosion experiments are conducted to investigate the influence of peening parameters on erosion. On this basis, RSs induced by WJP are studied in relation to the peening parameters. In addition, the coupled Eulerian–Lagrangian (CEL) technique is used to model and simulate the dynamic impact process of WJP on Al6061-T6. The influence of peening parameters such as jet pressure p, jet traverse velocity v_f, and the number of water jet pass n on the modification of residual stress field (RSF) is examined by simulation and experiment. The influence of incidence angle α and water jet diameter d on RSF is also investigated by simulation. Results show that compressive RS σ_crs is a result of the action of water-hammer pressure alone. Furthermore, σ_crs increases with an increase in p, n and α. The optimal peening parameters for Al6061-T6 are found to be p = 60 MPa, v_f = 2000 mm/min, n = 4, α = 90 deg and d = 2.0 mm. Finally, the depth of compressive RS layer D₀ increases greatly with an increase in water jet diameter d and can reach 984 μm.

Abrasive waterjet (AWJ) peening can be used for metal surface strengthening by introducing near-surface plastic strain and compressive residual stress. The present studies seldom focus on residual stress by AWJ peening of targets with different geometrical features. In fact, those targets usually exist on some machine parts including gear roots, shaft shoulders, and stress concentration areas. According to Hertz theory of contact and Miao's theoretical model for predicting residual stress of flat surface, this paper developed a theoretical model for investigating residual stress of targets with different geometrical features including concave arc surface, concave sphere surface, convex arc surface, and sphere surface. AWJ peening of targets with different geometrical features and different radii of Gaussian curved surface was simulated by abaqus. Theoretical results were consistent with numerical simulation results and published experimental results (H. Y. Miao, S. Larose, et al., 2010, “An analytical approach to relate shot peening parameters to Almen intensity,” Surf. Coat. Technol., 205, pp. 2055–2066; Cao et al., 1995, “Correlation of Almen arc height with residual stresses in shot peening process”, Mater. Sci. Technol. 11, pp. 967–973.), which will be helpful for predicting residual stress of gear roots, shaft shoulders, and stress concentration areas after AWJ peening. The research results showed that under the same peening parameters, σmax, σtop, dmax, and dbottom in concave surface (including concave arc surface and concave sphere surface) were the maximum; σmax, σtop, dmax, and dbottom in convex surface (including convex arc surface and sphere surface) were the minimum; for concave surface, σtop, σmax, dbottom, and dmax decreased, respectively, with target radius; for convex surface, σtop, σmax, dbottom, and dmax increased, respectively, with target radius.