Quantitative CLSM roughness study on early cavitation-erosion damage

Surfaces exposed to cavitation-erosion in four materials (Cu, brass CuZn30, austenitic steel 1.4301 and duplex steel 1.4462) using confocal laser scanning microscope (CLSM) were studied. This technique allows the quantitative evaluation of roughness caused by the plastic deformation of metallic surfaces during the exposition to cavitation-erosion through quantitative parameters, such as average deviation (Ra), standard deviation (Rq), skewness (Rsk) and surface roughness parameter (Rs) (real surface/projected area). The present work revealed a sudden Rs increase in the transition between the incubation stage (IS) and erosion stage (ES), while the skewness showed an evident reduction after the transition in all tested materials. It is concluded that the Rsk and Rs parameters can be employed for the early recognition of the erosion initiation in the four tested materials.