Study of the Corrosion Resistance of Type 304L and 316 Austenitic Stainless Steels in Acid Chloride Solution

The corrosion resistance of type 304L and 316 austenitic stainless steels in 2M H2SO4 at 0-1.5%NaCl concentrations was studied through potentiodynamic polarization technique and optical microscopy analysis. The corrosion rate, pitting potential, passivation potential and surface morphology of both steel where significantly altered by the Cl- ion concentration, alloy composition and metallurgical properties of the steels. Results showed that 316 stainless steel significantly performed better than the 304L counterpart with the unusual phenomenon of decreasing corrosion rate with increase in Cl- ion concentration. 304L steel showed no passivation and resistance to pitting after 0% NaCl concentration coupled with increase in corrosion rate. Despite similar elemental composition, the presence of molybdenum had a strong influence on the corrosion resistance and passivation of 316 steel. The surface morphology of 316 steel showed mild deterioration compared to severe surface deterioration, and visible micro/macro-pits on 304L