Why Does Crevice Corrosion in Stainless Steel Happen?

Crevice corrosion is slow and invisible at first, but once it picks up the pace, it’ll become far more deadly and harder to deal with than you’d ever expect!

It is highly localized and can even lead to structural failure, a more agonizing fact here is that nothing would even feel off to you, on the surface at least!

But why does it happen? Are there any signs? If any, then what?

These are the questions that we’ll be answering in today’s article, so let’s understand why crevice corrosion in stainless steel happens.

Crevice Corrosion in Stainless Steel: Why It Happens?

We know that stainless steel doesn’t usually corrode, due to the presence of the passive film of chromium oxide (Cr₂O₃).

However, it can corrode under some special circumstances.

Let’s try to understand how crevice corrosion in stainless steel happens and what exactly goes on deep down in the crevice:

Phase 1: Oxygen Runs Out

In confined geometrical spaces, like tight crevices, oxygen is consumed at a much faster rate than it can be replenished, so maintaining the passive layer of Cr₂O₃ becomes arduous.

So, stainless steel can’t remain very stainless if it doesn’t get much oxygen for an extended period of time.

Phase 2: Metal Starts Breaking Down

In this phase, a galvanized cell forms, and inside the crevice, metals dissolve and electrons are released.

On the outside of the crevice, electrons are accepted, and oxygen is reduced.

In simpler terms, in the absence of oxygen, the chromium oxide layer stops repairing itself, and the metal inside that layer lies bare and exposed, which makes it vulnerable to corrosion!

Phase 3: Acidification Takes Place Inside the Crevice

The low pH induces metal dissolution, and a never-ending loop begins, preventing the reformation of the protective layer, ultimately resulting in pitting, cracking, and potential structural fallout.

The more acidic it gets, the more corrosion will take place, while everything will look completely fine on the surface!

Conclusion

Crevice corrosion is a serious issue, and one that needs to be addressed and tended to as soon as possible.

And to do that, you need someone who knows what they’re doing, and that’s what our knowledgeable team of metal corrosion testing in Madison is here for!

We’re here to help, and we know where to look.

Ring us up right this instant if you think something’s off!