Impact of Minor Changes in Molybdenum Content on the Localized Corrosion Resistance of Austenitic Stainless Steels

ABSTRACT As an alloying element, molybdenum has a positive impact on the localized corrosion resistance of stainless steels and Ni‐based alloys. Nevertheless, the impact of minor changes from 0.5 to 1.0 wt% within the composition boundaries of SS316L on localized corrosion resistance is poorly understood. This study investigates the influence of these variations on the localized corrosion resistance of SS316L. Using the potentiodynamic–galvanostatic–potentiodynamic (PD–GS–PD) technique, the crevice corrosion repassivation potential ( E R,CREV ) was measured in deaerated natural seawater at various temperatures for three stainless steel grades with differing Mo contents. The E R,CREV of SS316‐2.5Mo increased by approximately 125 mV at 10°C, 139 mV at 20°C, and 218 mV at 35°C when compared to SS316‐2Mo. Microstructure analysis after PD–GS–PD revealed Mo‐enriched precipitates for both SS316‐2.5Mo and SS317‐3Mo. Potentiodynamic polarization test was conducted in pit/crevice‐like conditions, showed improved corrosion resistance in SS316‐2.5Mo, as indicated by higher breakdown and Flade potentials, a wider passive range, particularly in 1 M [Cl − ] (pH = 0).