Corrosion of Stainless Steels S31603, S31655, and S32101 in Sulfuric Acid Solutions: Effects of Concentration, Chlorides, and Temperature

This study investigates the corrosion behavior of three stainless steel grades at two H2SO4 concentrations, namely 1 wt% and 10 wt%, with varying NaCl concentrations in range from 500 mg/L to 10,000 mg/L. Dissociation sulfuric acid yields hydrogen (H+) sulfate () ions, former which lowers pH value a solution while latter increases concentration ions that act as inhibitor. The equilibrium chemistry solutions was defined test temperatures 22°C, 50°C, 90°C, 130°C, correlated observations on electrochemical microstructural examination materials. results showed clear differences main form between concentrations. In H2SO4, pitting major attack presence chlorides, whereas uniform dominated H2SO4. tendency for under various conditions consistent, but there were their resistance corrosion. chloride-to-sulfate activity ratio, , found be key parameter defining occurrence all alloys. H2SO4-NaCl systems, no occurred ratio below 10, higher values inducing attack, particularly described novel are presented discussed this paper.