The Electrochemical Characteristics of Cr30Mo2 Ultra Pure Ferritic Stainless Steel in NaCl Solutions at Different Temperatures

The electrochemical characteristics of Cr30Mo2 ultra pure ferritic stainless steel in 0.01-2 M NaCl solutions at different temperatures (25-90 °C) had been investigated using different electrochemical techniques of potentiodynamic polarization, electrochemical impedance spectroscopy, capacitance measurements (Mott-Schottky approach) and potentiostatic polarization measurements. The results revealed that the pitting corrosion behavior of this stainless steel was found to be dependant on the temperature and chloride concentration of the solution. As the temperature and Cl- concentration were increased, the pitting potentials of the stainless steel shifted to negative direction, the impedances of passive films decreased and the donor densities (ND) in oxide films calculated from the Mott-Schottky plots increased in the range of 1.6 - 7 x 1021 cm-3. Besides, the incubation time of pitting corrosion of Cr30Mo2 stainless steel shortened with the increase of temperature. Combining with micrographs of pits, it was recognized that the pitting corrosion resistance of Cr30Mo2 stainless steel declined in the concentrated NaCl solution at higher temperature.