Stainless steel is always praised for its high resistance to corrosion. The main reason why it enjoys such superior corrosion resistance when compared to other metals is the addition of chromium. Other elements, such as molybdenum and nickel, also contribute towards the metal’s superior resistance, but chromium is the key component, and all grades of stainless steel comprise at least 10.5% of this valuable element.
To understand why it’s important for a metal to be so resistant to corrosion, we first need to fully understand just what corrosion really is.
What Is Corrosion?
Corrosion is a natural phenomenon. Nature, in all its perversity, always wants to combine elements, often to man’s detriment! Iron, for example, when combined with water and oxygen, will rust. Remove one of the elements, however, and corrosion is all but eliminated. It’s fascinating to note that trains (made largely of iron) that were blown up in the Arabian desert during WWI are almost perfectly preserved because, although there is oxygen, there is no rain. Similarly, an iron ship sunk and lying deep under water rust extremely slowly because, although there is water, there very little oxygen. Yet put that same ship on the beach where it is exposed to tides and air, and it will rust very quickly.
How Does Chromium Protect Stainless Steel?
The chromium in stainless steel loves oxygen, combining with it on the surface of the metal to form a thin coating of chromium oxide. The true marvel of this naturally-formed coating lies in three key properties:
- It is passive – it doesn’t influence or react with other materials.
- It is self-renewing – if it’s damaged or intentionally removed, it simply forms a new layer.
- It is tenacious – it stays “stuck” to the stainless steel and does not transfer to other materials.
Despite stainless steel’s impressive properties, it’s still extremely important to preserve and maintain the protective coating as much as possible. You can help the natural repair process of the chromium oxide layer by avoiding mechanical and chemical damage, and ensuring that there is always enough oxygen on the surface of the stainless steel.
Steelmor has been supplying and manufacturer stainless steel in South Africa for over 40 years. We’d welcome the chance to chat with you about the benefits of this amazing alloy, and how you can use it to help ensure the success of your next project.