Steel Grades: What’s in a Name?

Posted 9th June, 2015

One of the great things about metallurgy is that it’s an exceptionally diverse field. And as it’s such a rich and diverse area, there are thousands and thousands of variations in steel alone, based on many people’s tireless work experimenting with chemical compositions and mechanical properties.

West Yorkshire Steel has a comprehensive library of steel grades and compositions, which although expansive is by no means the complete list. The number of grades in the world must run into the tens of thousands, but is too many and varied to be compiled into one encyclopaedic document.


One of the difficulties is that people have reached similar results at similar times and with no defining authority to act as a ‘patent office of steel’, the various companies named their own steel as they saw fit as discoverers.

In an effort to combat this, the BS970 was introduced, whereby all steels were given an ‘EN’ number. One theory about why ‘EN’ was chosen was it stood for ‘Emergency Number’ when British Standards were fighting to try and bring a semblance of order to the vast array of available steel grades. This is just anecdotal, but shows the perception of the task being undertaken. Even EN24, a common steel grade, had been developed by a number of different companies and one product was called many things such as A13, KE805, Versatile, Sanbold 24, CNCOH3, Spear 524 and G5 Special, dependent on which steel manufacturing company you were talking to. Clearly this would have been a very confusing time to be a steel buyer, as you could never be absolutely certain of what you were buying!

Unfortunately, by the time that many people had become accustomed to using the BS970 EN standard, it was already obsolete. It was replaced by the six character method, where the first three digits show the steel type, the fourth is a letter to help give information about the steel and the last two indicate the carbon content. For example, 709M40 and 817M40 are both existing steel types and both give a hat tip to the American AISI method of using the last two digits to show carbon content.

This American-friendly method of labelling British steel types is leaning towards an International agreement, but it’s not as simple as that. The German office has the DIN or Werkstoff method of labelling, the DIN method being much more complicated than the British designations, for example the 301 stainless grade is known as “X 10 CrNi 18 8” and is a 0.% carbon, 18% chromium, 8% nickel stainless steel.

In all fairness, names given to steel varieties are never going to make much sense to the general public and unless you need to know about the differences between the AFNOR, DIN, BS, UNI or JIS methods of labelling, it’s unlikely to be something that you will invest any serious time contemplating. However, if there’s ever a time when such things are needed, West Yorkshire Steel will continue to keep our database up to date and will always aim to help and share our passion and expertise.