Localized corrosion of stainless steel, namely pitting and crevice, affects seriously the performance of these materials in service. In this paper, the design of experiment (DOE) is used to study the influence of temperature, pH and chloride concentration on the pitting and crevice corrosion of AISI 304L (UNS S30403) stainless steel. DOE approach enables to reduce the number of tests (anodic potentiodynamic polarization) necessary to study the effect of several parameters on the passivity breakdown potential. The use of DOE provided a regression equation that was analyzed by comparison with laboratory and literature results. Among all these parameters, the temperature has the most significant effect on pitting corrosion resistance.

Stainless steels are prone to localized corrosion (pitting and crevice) in the presence of oxygen and chlorides over a critical threshold. Prediction of the corrosion behavior of stainless steels in chloride containing environment is of great importance; for this reason, Pedeferri's diagram is proposed to define corrosion and passivity (perfect and imperfect conditions) as a function of the potential and chloride content. In this paper, the first effort is carried out to define electrochemical conditions to obtain the diagram. Potentiodynamic and potentiostatic polarization tests are performed on AISI 304L type stainless steel. Localized corrosion potential and critical chloride content found with two different methods are in fair agreement. Pedeferri's diagram is built for type 304L stainless steel at room temperature and pH 6. Corrosion, perfect and imperfect passivity regions are separated by scattering band for localized corrosion and repassivation potentials.