Protecting Metals From the Inside Out: Tackling Crevice Corrosion in Aluminum and Stainless Steel

Metals have a significant role in nearly all industries, such as the aerospace industry, construction, marine, and manufacturing industries. Nevertheless, even the most solid metals are subject to silent damage in the course of time in conditions of being affected.

It is worth noting that the main point that underlines the existence of the problem is the fact that crevice corrosion of aluminum and crevice corrosion in stainless steel are two of the most common but the least sought-after forms of metal decay that may undermine their safety, strength, and performance.

Crevice corrosion takes place in the narrow areas where the concentration of oxygen on one side of a metal surface, compared to the other, seems different, under gaskets, bolts, rivets, or deposits.

Learning About Crevice Corrosion in Aluminum

In the case of crevice corrosion of aluminum, the issue is usually produced when the protective oxide layer that covers the aluminum against corrosion disintegrates within a narrow gap or joint. Aluminum is naturally deposited in the passive layer that prevents corrosion; however, when wet, or when in places with chlorides or stagnation, the layer may break down.

When all the oxygen is taken away inside a crevice, the trapped space becomes more acidic, and corrosion is increased. Such damages are commonly observed in the aircraft constructions, marine fittings, and industrial machinery that are subjected to salty or wet weather conditions.

The prevention of crevice corrosion in aluminum has to do with regular inspection, proper sealing, and corrosion-resistant coating. To minimize the risk, the selection of design structures that will reduce tight joints and crevices could be a significant aspect.

Challenges With Crevice Corrosion in Stainless Steel

Although stainless steel is widely celebrated due to its resistance to corrosion, crevice corrosion may develop in the stainless steel when the conditions are favorable. The strength of stainless steel is the presence of chromium oxide film, which surrounds the surface to prevent rusting. But once that protective coating is broken within a crevice, oxygen is no longer able to replenish it, and thus the chloride ions are able to assault the metal. This contributes to pitting in the area and subsequent failure of the material.

Stainless steel crevice corrosion is especially worrying in the marine, chemical processing, and food industries, where it is common to have chloride environments. Better resistance can be obtained by the use of higher-grade stainless steel, like 316L or duplex alloys. It is also important to keep clean and passivate, as well as prevent stagnant areas.

Early Damage Detection and Prevention

Earlier detection and preemptive prevention are the keys to dealing with crevice corrosion. Corrosion testing, such as the electrochemical analysis, may be done regularly to establish the compatibility and performance of the material in certain conditions. This understanding helps the engineers to pick the right alloys, create an improved joint, and execute a protective cover to prolong the life of components.

Conclusion

Crevice corrosion can begin minimally at the beginning, but can have a huge impact on an organization, such as failure to do costly repairs, safety hazards, and failure to use equipment that comes at a cost in terms of time. The key to the prevention of crevice corrosion of aluminum and crevice corrosion of stainless steel lies in the understanding of how these processes take place.

In Corrosion Testing and Solutions, LLC, their main task is to find, test, and control the problems of corrosion by means of sensitive methods of electrochemical and environmental analysis.