Corrosion Failure Analysis of 304 and 2205 Stainless Steels in High-Temperature Condensate Containing Chloride Ions

The corrosion failure of 304 and 2205 stainless steels in fuel cell was analyzed by measuring the chemical compositions of steel substrate and ions concentration of condensate as well as corrosion morphology observation. It revealed both of them, especially the 2205SS, were severely corroded after one-month exposure. The austenitic 304SS with higher Ni content was found to be more corrosion resistant than 2205SS in this environment. The primary cause for the pitting corrosion of stainless steels in fuel cell system was the acidic high-temperature condensate which contains chloride ions released from thermal insulation powders. To resolve or mitigate this problem, the flue gas leakage from the system shall be avoided or controlled. The aggressive substances (chlorides, acids, etc.) in the thermal insulation powders should be eliminated or reduced. In addition, other materials with higher Ni content (e.g., Ni-based alloys) might be feasible in this environment.