Cavitation resistance, microstructure and surface topography of materials used for hydraulic components

The cavitation resistance of a stainless steel and two flame thermal spray coatings was tested in laboratory according to ASTM G32 standard. The time-variation curves of cumulative volume loss, erosion rate and roughness parameters were related to the microstructure of the samples and to the wear mechanisms. Pores, unmelted particles and other microstructure defects prevented the coatings from showing an incubation period during the tests, while the stainless steel exhibited the expected incubation, acceleration and maximum rate stages. In the stainless steel, a correlation between the transition from incubation to acceleration stage and the Rsm/Rq and Ry/Rq ratios was established.