Effect of Cyclic Heat Treatment Process on the Localized Corrosion Resistance of 409 Ferritic, 430 Ferritic, 3163 Austenitic and 444 Ferritic Stainless Steels for High Temperature Applications

The corrosion resistance of as-received 409 ferritic, 430 ferritic, 444 ferritic and 316 austenitic stainless steels was studied in 0.05M H₂SO₄/3.5% NaCl solution by potentiodynamic polarization and potentiostatic measurement and compared to their counterparts subjected to repetitive temperature variation at 1000°C. As-received 409 ferritic steel exhibited the highest corrosion rate at 8.406 mm/y compared to as-received 316 austenitic steel with the lowest corrosion rate at 3.130 mm/y. Corrosion rate of heat treated 409, 430 and 444 ferritic stainless steels significantly increased to 10.766 mm/y, 5.694 mm/y and 6.096mm/y while the corrosion rate of as-received 316 austenitic steel decreased to decreased to 0.409 mm/y. As-received 444 ferritic steel exhibited the weakest resistance to pitting corrosion while as-received 409 ferritic steel exhibited the most significant metastable pitting activity. Pitting corrosion susceptibility of heat treated 409 ferritic, 316 austenitic and 444 ferritic steel decreased significantly to 0.137 V, 0.384 V and 0.096 V while heat treated 430 ferritic steel exhibited significant improvement in pitting corrosion resistance.