Anodic Polarization Behavior of High‐Purity 13 and 18% Cr Stainless Steels

Potentiodynamic polarization curves were obtained in and in for 13 and 18% Cr ferritic stainless steels containing 0–5% Mo. The critical current density for passivation was decreased by molybdenum additions in both acids, the decrease being more pronounced for the 18% Cr steels than for the 13% Cr steels. No complete passivity was obtained for the 13% Cr steels, even with the 5% Mo addition, in . The addition of 1% Mo to 18% Cr steels resulted in complete passivity in . Pitting potentials in at 25°C increased linearly with molybdenum content. Pitting potentials increased more rapidly for the 18% Cr steels than for the 13% Cr steels. All alloys suffered pitting corrosion in 10% ; however, alloys of higher Cr‐Mo content were the least pitted and showed the smallest weight losses.