Effect of chromium on the corrosion behavior of low alloy steel in sulfuric acid

The effects of a chromium (Cr) addition on the corrosion resistance of low alloy steel used in flue gas desulfurization systems were examined by electrochemical (potentiodynamic polarization tests, linear polarization measurements and electrochemical impedance spectroscopy) and weight loss measurements in a 10 wt% H2SO4 solution at room temperature. All measurements revealed a decrease in corrosion rate with increasing Cr content. SEM, EPMA and XPS examinations of the corroded surfaces after the immersion test indicated that 0.6% Cr addition decreased corrosion damage to the steels because protective Cr oxides formed in all the rust layers and Fe oxides dominated over Fe sulphate compounds in the inner rust layers.