Evaluation of cavitation erosion–corrosion degradation of mild steel by means of dynamic impedance spectroscopy in galvanostatic mode

Cavitation erosion and corrosion of mild steel was studied by means of a vibratory facility in 3% w/w NaCl solution. Dynamic Electrochemical Impedance Spectroscopy (DEIS) measurements were carried out in the galvanostatic mode to allow on-line monitoring of impedance parameters in cavitation failure. The results, based on an analysis of instantaneous impedance spectra, correspond to degradation under the influence of cavitation erosion–corrosion. It has been shown that a change of pseudo-capacitance corresponds to an increase in sample roughness, while the charge-transfer resistance determines changes in the corrosion rate under the combined mechanical and electrochemical factors.

Research highlights
► Galvanostatic DEIS allow investigation of cavitation erosion–corrosion.
► Evolution of CPE corresponds to changes of surface roughness.
► Rct drop precedes mechanical degradation and allow corrosion resistance monitoring.