Evaluation of Corrosion Life of Fin Materials

Abstract

The present paper concerns with the evaluation method of localized corrosion life of fin materials (aluminum and copper) used for air cooled heat exchangers. Cyclic dry-wet corrosion tests were performed in a laboratory, in which component models were exposed to the condition simulating the service condition of the component. Moreover, field exposure tests of component models were performed. Comparing with the two tests, the acceleration factor of the laboratory tests was determined. It turns out that the corrosion feature of the fin materials was localized corrosion, such as pitting corrosion, associated with general corrosion. Corrosion damage of fin materials was evaluated by tensile tests and the statistical distribution of the test results was discussed in terms of the model developed on the basis of the fracture mechanism. Scanning electron microscopic observations indicated that the fracture of fin materials occurred at the root of the pit and the statistical distribution of the tensile test data was well described by the weakest link model. Thus, the corrosion lives of the fin materials were estimated by means of the extreme value statistical analysis and the results were in good agreement with the actual localized corrosion data obtained from some operating machine components.