Corrosão de aços inoxidáveis empregando mapas de impedância

Abstract

Stainless steels account for steels with different in composition and microstructure. Thus, the corrosion behavior is consequently different. To assess this, steels with PREN ranging from 11% to 35% were analyzed by polarization curves. The main motivation of this work was the evaluation the behavior of each stainless steel via different techniques (electrochemical impedance spectroscopy and equivalent electrical circuit), as well as the use of the new technique of impedance maps, on the influence of PREN on the corrosion in 3.5% NaCl at 25ºC. From these curves, the pitting potential and corrosion current density were obtained. In addition, maps were used diagram electrochemical impedance to view the effect of the applied potential, from the cathodic potential up to the pitting potential of these steels. It can be observed that the modulus of impedance decays abruptly when pitting take place. Moreover, there is a change in the angle characteristic for frequencies in the order of 1 kHz. For two stainless steels, i.e,. UNS S30400 and UNS S31600, the diagrams of maps were used to monitoring the evolution parameters related to an electrical equivalent circuit for the applied potentials.