Why is stainless steel, stainless?

Dec 17, 13 Why is stainless steel, stainless?

Ever wondered what stainless steel is and why we call it stainless? It’s used in many of the things we take for granted and as a strong alloy it can meet many of our project requirements. An additional benefit is that life cycle costs can be low because the material is 100% recyclable and over 50% comes from re-melted stainless steel scrap. However, there are over 60 different types with many different properties so you may need a little help.

How was stainless steel discovered?
Steel is formed from mixing iron and carbon in low oxygen environments but it is prone to rusting when it comes into contact with air and moisture. In 1913, English metallurgist Harry Brearly discovered stainless steel by accident. In trying to improve rifle barrels he found out that they could become more resistant by adding chromium.

Chromium is the 24th most abundant element in the Earth’s crust and is often distributed through volcanic eruptions. South Africa and Kazakhstan have the highest stash geographically but South Africa produces two-fifths of the world’s mined chromite. It can also be found in Russia, India and Turkey.1

How do we make it?
In modern production, stainless steel is produced by mixing steel with 10.5% chromium. A film of chromium oxide forms on the surface of the new material (it is all but invisible) that resists corrosion. More than that, it is self-repairing, so even if the surface is damaged, it can repair itself (so long as there is enough oxygen present). Chromium also bonds well with the iron thus forming a more solid structure. These properties are improved by increasing the chromium content and adding other elements such as nickel and nitrogen, depending on how the stainless steel will be used.2

Why doesn’t it stain?
Stainless steel doesn’t corrode, rust or stain in the same way as ordinary steel but it is not entirely stainless. If there is not much oxygen (i.e. the chromium oxide film is not able to self-repair), if the air is not circulating much or if there is too much salt in the environment (which attacks the film), then stainless steel can actually stain.

Do your research
There are many additional benefits of using stainless steel – its resistance to heat/fire, the fact it’s easy to clean and aesthetically pleasing, as well as the ease with which it can be produced. However, it can be difficult to navigate towards the right type for your project. Metalmen are hands-on metal supply specialists and can help you determine the correct form of stainless steel that you need for your projects. Our stock is quality-grade Metalmen Sales 316 stainless steel, and is sold in a variety of forms, including: The 300 series, for example, is tough and can handle a high range of temperatures (e.g. a 316 stainless steel coil may be receptive to cryogenic uses). Do your research and it will be well worth the work.

Be the first to like.

Be Sociable, Share!
    Shares
    Share This