Impedance fitting of 254SMO and AISI 304 stainless steels under pitting conditions

摘要

Impedance measurements were performed on 254SMO stainless steel (SS; UNS S31254) and AISI 304 SS (UNS S30400) under pitting conditions in solutions containing chlorides at 25°C and 60°C. A complex nonlinear, least-squares program was used to determine the parameters of the transfer functions, including an ohmic resistor in series with a chain of series-connected, parallel, resistor-capacitor (RC) circuits. The impedance data satisfy Kramers-Kronig (K-K) transforms for UNS S31254 SS but do not fulfill K-K relations for UNS S30400 SS.