Improving surface hardness of austenitic stainless steel using waterjet peening process

The present study addresses the effect of multiple jet passes and other parameters namely feedrate and pressure in waterjet peening (WJP) of austenitic stainless steel 304. An analysis of surface integrity was used to evaluate the performance of different parameters in the WJP process. An increase in the number of jet passes as well as pressure leads to a higher roughness and more erosion of the surface. However, the feedrate shows a reverse effect on the surface roughness and erosion. The surface microstructures also show the mechanism of material removal process involving initial and evolved damages. The subsurface hardness shows that treating the surface with a higher number of passes and pressure produces a higher increase of hardness and also a deeper hardening layer. But, a reverse effect on the subsurface hardness was found for the feedrate. Furthermore, cross-sectional microstructures show a higher density of slip bands in the deformed grains of the specimen treated with a higher number of jet passes and pressure. However, the amount of slip bands in the deformed grains is lower with increasing feedrate.