Dynamic Electrochemical Impedance Spectroscopy in Galvanostatic Mode as a Tool for Passive Layer State Monitoring in a Chloride Solution Under a Mechanical Load.

Mechanical stress is one of the factors influencing the initiation of pitting corrosion and deterioration of the protective properties of the passive layer on stainless steel. The tests carried out on AISI 304L stainless steel showed that, in the 3.5% NaCl environment for samples loaded in the elastic and plastic range, no pitting corrosion initiation was observed. Only mechanical damage of the passive layer occurred. Galvanodynamic electrochemical impedance spectroscopy (g-DEIS) was used as the measuring technique. This technique ensures the monitoring of corrosion processes at zero external current (I = 0) and no potential perturbation of the system. It also allows one to perform many measurements, so that short-term changes such as cracking of the layer and its repassivation are possible to monitor.