Controlled modification of the surface morphology and roughness of stainless steel 316 by a high speed submerged cavitating water jet

The aim of this paper is to demonstrate the possibly of using the cavitation phenomenon, primarily a cavitating water jet, for the controlled surface modification of metallic biomaterials. Stainless steel 316 (an austenitic face centered cubic metal) was subjected to high-speed submerged cavitating jets under certain working conditions, and different exposure times. The force generated by the collapse of cavitation bubbles is used to modify the surface topography on micro- and nano levels. Optical microscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and interferometric profiling were used to characterize the surface morphology before and after cavitation treatment. The results confirm that at short exposure times, the observed characteristic features in the microstructure - holes and hills without material loss and wavy configuration - can be related to plastic deformation, while longer exposure times lead to erosion accompanied by material loss. The results related to the different stages of cavitation damage demonstrate the possibility to use cavitation as a micro-nano fabrication method for the modification of biomaterial surfaces, e.g. for the controlled and convenient increase of surface roughness.