Corrosion polarization and passivation behavior of selected stainless steel alloys and Ti6Al4V titanium in elevated temperature acid-chloride electrolytes

Abstract The corrosion polarization behavior of 439ll ferritic (439ll), 316L austenitic (316L), and NO7208 nickel-chromium-aluminum-iron (NO7208) stainless steels, Ti6Al4V titanium (Ti6Al4V) alloys was studied in 4 M H 2 SO + 5% NaCl solution at 35 70°C. Corrosion rate ( C R ) the were generally higher alloy exhibited resistance to general 35°C (0.067 0.050 mm/year) while most reactive (0.506 mm/year). Passivation evident on plots alloys. pitted 1.04 V with passivation range 0.17 V. Metastable pitting occurred 0.02 ceased 0.19 Pitting absent from plot though it metastable −0.39 passivated −0.21 At 70°C, lowest (0.392 mm/year), 21.868 mm/year. increased by 97.63%, 91.18%, 82.83%, 97.69% potential shifted cathodically 70°C signifying dominant cathodic processes. no evidence. Open circuit measurement showed that electronegative electropositive due significant growth its protective oxide. Grain boundary visible total surface deterioration Pseudo pits 35°C. degradation grain NO7208.