Effect of pressure of pulsating water jet moving along stair trajectory on erosion depth, surface morphology and microhardness

The objective of the study is to investigate the erosion effects of periodic water clusters interacting with flat AISI 304 surface to evaluate erosion regimes, surface morphology and variation in the subsurface microhardness below the disintegrated grooves. Stairs trajectory within the standoff distance 5–101 mm with step height 2 mm and length 20 mm was used. The pulsating water jet was changed by varying the supply pressure of the liquid from 40 MPa–100 MPa, at a traverse speed of 5 mm/s which is equivalent to constant impingement distribution of 4000 impingements per mm. Morphology of the PWJ defines different erosion regimes based on specific value of supply pressure and standoff distance. Increasing of supply pressure shifts prevalence of both impact pressure and stagnation pressure at higher standoff distances leading to the delay in formation of incubation, acceleration, culmination, depletion, and termination regime. Impinged surface features such as micro-pits, craters, upheaved surface and isolated voids near the periphery of the trace were observed along with PWJ footprint. The values of the micro-hardness showed strengthening of material subsurface at selected standoff distances. At certain standoff distance effect of supply pressure is inverse to micro-hardness values. Determination of studied technological parameters can be used for effective surface peening operation at v > 5 mm and surface activation of the metals. Results opens a new avenue for determination of erosion resistance of material.