Effects of Molybdenum on Improvement of Anti-Corrosion by Plasma Ion Nitriding for Austenitic Stainless Steels

摘要

Corrosion characteristics of SUS 304 and SUS 316L under the marine environment were investigated by plasma ion nitriding at 450 degrees C with a gas ratio of 25% N-2 and 75% H-2 for 10 hours. In the anodic polarization experiment performed in natural seawater, noble pitting potential and wide passive region were exhibited in SUS 316L due to the synergistic effect of molybdenum and nitrogen even after plasma ion nitriding compared with SUS 304. In the corrosion rate obtained by an extrapolation method after plasma ion nitriding, a similar result of corrosion current density represented in SUS 304 while lower corrosion current density was analyzed in SUS 316L.