Stainless DOES Corrode!

Stainless steel is all around us. Many incorrectly assume stainless steel does not corrode. Stainless steel does corrode and when it does the results can be disastrous, whether it's a hole in your dishwasher or a failed industrial plant.

Stainless steel was first made in Sheffield, UK, in 1913.

Unlike rusting, stainless steel corrosion is highly localised and random. Tiny holes called pits can drill through a substantial thickness of steel in a relatively short time. The pits can cause leaks or act as points from which cracks initiate and can cause some of the most catastrophic industrial accidents known.

Why stainless steel fails has long been a mystery, but today - Researchers claim to have solved it.

'Stainlessness' is created by alloying iron with chromium. As the steel ingot cools after it has been made, tiny sulphur-rich impurity particles, about 10 millionths of a metre in diameter, solidify at a lower temperature than the steel, remaining molten for a time after the metal has solidified.

Using an advanced new microscope researchers found a region around these impurity particles that has significantly less chromium than the rest of the steel. During cooling of the steel the impurity particles 'suck' chromium out of the steel around them, creating a tiny nutshell of steel that is not stainless.

Corrosion of this layer, just one 10 millionth of a metre thick, is the virus that triggers the main attack.

Stainless is used in countless engineering applications and, in general, it has very good resistance and performs well but it is susceptible to this devastating pitting corrosion. Now we've worked out the sequence of events that cause it, we know what causes this Achilles heel, and we can use this information to work out how to fix it.

Stainless Steel does corrode. The picture above is a stainless steel vessel being pickled. Pickling paste is one of several products ICS can use to remove corrosion. ICS can advise you of the best chemical to use on a case by case basis.