Abstract：In this study, the jet velocity is controlled by changing the jet pressure on a new designed pre-mixed water jet modification system. The surface strengthening effect at different jet velocities on 18CrNiMo7–6 carburized steel is evaluated from two aspects of surface roughness and residual stress. Based on the impact stress analysis of water and shot in jet, the relationship between jet velocity and impact stress is established. With the jet velocity represented by the nozzle inlet pressure, experiments were carried out by using a single factor method. At the pressure below 35MPa, the impact of shot is the main reason for the plastic deformation of sample surface. The surface roughness and residual stress, as well as the layer depth of residual stress field, increase with the shot velocity. However, as the jet velocity exceeds 178m/s, the increase of surface roughness is obvious while the residual stress does not increases significantly. It is indicated that a good modification can be achieved in the pre-mixed water jetting with the particle velocity of 143–178m/s.
2022, 
