Crevice corrosion is influenced by the choice of metal, the operating conditions and environment, and the presence of a crevice or crevice-former. By creating different conditions between a crevice and the bulk surface, an electrochemical cell can be created and pitting corrosion begins. However, within the crevice, corrosion conditions become far more aggressive than in the bulk – due to increasing concentrations of acidic species and the absence of oxygen that would otherwise support re-passivation of the protective passive film.
The best defence against crevice corrosion is to limit the potential for crevices. The most common source of crevices is around bolted connections, underneath bolts or washers. However, tight corners, dead spots in the flow of liquid through a component or surface damage such as deep scratches or gouges can all act in the same way as a crevice. Limiting bolted connection and joints, producing components with radii corners rather than sharp angles, designing components to experience more uniform flow, and polishing surfaces can all contribute to reducing the likelihood of crevice corrosion.
If you have any more questions about selection corrosion resistant alloys, please contact us today. A member of our team will be more than happy to help and can also advise you on the best option for your application.