Critical Pitting Temperature of Super 13Cr Stainless Steel

The pitting corrosion behavior of super 13Cr stainless steel was studied by electrochemical test and chemical immersion methods, and the pitting morphology was observed by SEM. The results show that there was a difference of 4 ℃ in the critical pitting temperatures of the super 13Cr stainless steel determined by electrochemical and chemical immersion methods. This is due to the promotion function of strong oxidation of FeCl3 in chemical immersion. Chemical immersion appraisal is mainly suitable for comparison of the pitting performance of several materials, whereas the electrochemical test can further describe the critical condition of pitting. Meta-stable pitting with a diameter less than 30 μm was formed on material surface just below the CPT, while stable pits could only be formed above the CPT.