Cavitation Damage under Pressure Conditions by a Vibratory Test

As pumps, valves and pipes are damaged by cavitation attack, the method of evaluating resistance of materials, of which these apparatuses and pipes are composed, has been of considerable concern. The vibratory test is one of the widely used methods to evaluate resistance of materials to cavitation damage. However, there is no enough knowledge to determine by this vibratory method the resistance which materials will offer during exposure to cavitation attack in various surrounding conditions.The present paper deals with the cavitation damage of carbon steels and stainless steels, of which pumps, valves, and pipes consist. All steels were tested with a 17.7 kHz vibratory unit at an amplitude of 35 μm (peak-to-peak) in water at 298 K under pressure conditions from the atmospheric pressure to 0.3 MPa.Results obtained are summarized as follows:(1) Under pressure conditions beyond the atmospheric pressure, the cavitation erosion behavior of tested steels, described by means of the mean depth penetration rate (MDPR) versus eroded volume, was classified into three zones; (a) a transition zone, (b) a zone with maximum erosion rate, and (c) a zone in which the erosion rate decreases.(2) The experimental equation was derived which describes the correlation between the MDPR and the testing pressure (P) as Max (MDPR)=a·Pn (a, n: const.).