The Corrosion Attack on Stainless Steel 316L and WC-Co in High Sulphate-Chloride Ratio

Abstract

Austenitic stainless steels and cermets alloy has been used extensively in many sectors due to their highly resistance to corrosion attack and excel in mechanical properties. However, in corrosive media both materials are susceptible to corrosion attack especially in seawater and high temperature. Cermet alloys are a combination of ceramic and metal. Therefore, cermets exist in high corrosion resistance in aqueous media and the corrosion rate is complex to identify. This paper presents the corrosion mechanism of 316L and cermets alloy exposed to high concentration of sulphate in the salinity of seawater. The solution (media) was prepared according to the same composition as seawater including pH, salinity and dissolved oxygen. The corrosion mechanism were characterized to breakdown potential (Eb)of 316L which are the potential once reaches a sufficiently positive value and also known as pitting potential. This is the most point where localized corrosion susceptibility to evaluate and considered a potential, which could be an appropriate point according to any given combination of material/ambient/testing methods. TheEbvalue of 316L in high sulphate are higher compared to seawater in every temperature which elucidate that some anions accelerate corrosion attack whereas some anions such as sulphate behaves as inhibiting effect to 316L.