Logistic curve model of cavitation erosion progress in metallic materials

The authors previously found that the change in volume loss rate with the exposure time can be expressed by a logistic curve. In this study, the validity of this model is examined for various materials such as pure aluminum, carbon steels, stainless steels, cobalt alloys, and so on. The MDE (mean depth of erosion) d as a function of the exposure time can be expressed by three parameters α, β and c as in the following equation:d=αβt−1βln1+c1+ce−αtThe parameters α, β and c are derived from the relation between the nominal incubation period and the slope of the maximum rate stage, from the average thickness of the removed layer when the nominal incubation period is terminated, and from an arbitrary point (t0, d0) of the MDE in the maximum rate stage. We conclude that the calculated curve based on this model is in good agreement with the MDE data points for various materials, test conditions and test methods.