Modeling of the Critical Pitting Temperature between the Laboratory-Scale Specimen and the Large-Scale Specimen

Abstract

Critical pitting temperature (CPT) of 316L stainless steel with different specimen areas in 3.5 wt% NaCl solution was investigated by the potentiostatic method. The results showed that the CPT exhibited a decreasing tendency with the increase in specimen areas, which was attributed to the higher probability for large-scale specimens to attain a large pit depth than small specimens. Therefore, stable pitting is easier to form, resulting in a lower CPT. Subsequently, a Gumbel extreme function was applied to establish a model correlating CPT with the specimen area. The CPT was linear with the double logarithm of the specimen area and could be accurately predicted for large-scale specimens.