Identification of Corrosion Mechanisms of Stainless Steel with Metallography Cross Sections

Abstract

The metallography was used for evaluation of localised form of corrosion of stainless steel tubes of heat exchangers. The heat exchangers were in service for relative short period from few months to 2 years. The service conditions of these heat exchangers were different (temperature, medium, etc.) and caused penetration of tube walls. The metallography cross sections were used to identified the corrosion mechanisms. For all evaluated cases the different mechanisms were found – pitting corrosion, microbiologically induced corrosion, trans-crystalline corrosion cracking, intercrystallite corrosion cracking. Together with diffraction and elementary analysis of corrosion products the metallography evaluation was used for identification of corrosion mechanisms.