Localized Corrosion Behavior of Nuclear Grade Nitrogen-Containing Austenitic Stainless Steel 316NG

The localized corrosion behavior of nuclear grade nitrogen-containing austenitic stainless steel 316NG was studied in comparison with austenitic stainless steel 321 by electrochemical method, pitting corrosion testing, salt spray testing and slow strain rate testing (SSRT), respectively. The surface morphology of the stainless steel after corrosion was observed by optical microscopy and electron scanning microscopy. The results show that for stainless steels 316NG and 321, the rates of reactivation were 3.83% and 4.47%, the pitting corrosion rates were 10.74 g/(m²· h) and 45.97 g/(m²·h), salt spray corrosion rates were 2.14×10^-2 g/(m²·h) and 12.32×10^-2 g/(m²·h), and the sensitivity indexes of SCC were 0.078 and 0.10. The localized corrosion resistance of stainless steel 316NG was better than that of stainless steel 321 because of the existence of Mo and N in the stainless steel 316NG making localized corrosion resistance improve.