Corrosion Activity of Carbon Steel B450C and Low Chromium Ferritic Stainless Steel 430 in Cement Extract Solution

This study compares corrosion activities of carbon steel B450C and SS 430 (Mn in low content) exposed for 30 days cement extract solution. Iron oxide hydroxide were formed as products, addition to CaCO3, the presence Cr2O3 on 430. Because decrease pH, lost passive state when OCP shifted negative values, while showed positive maintaining its state. The SEM images confirmed that attack surface was less aggressive Nyquist plots EIS initially capacitive behavior later changed semi-linear diffusion impedance, which maintained firmly. phase angle Bode diagrams these changes. Two equivalent circuits applied. calculated values Rp increased over time (protective layer mainly oxide), steel, reached maximum value after 168 h then decreased, minimum approximately five orders lower than those stainless steel.