Information Library


What does 'EN' and 'BS970' mean?

What do EN and BS970 actually mean?

The original 'EN' or 'Emergency Number' material designation was developed during the years of WWII to improve the standardisation of steel reference specifications. This was to aid production and selection of materials to manufacture components, especially for the production of guns, planes and automobiles. (previous to this, old maufacturing drawings only refer to 'Grade A, B, C or D' -railway engineering. Grade 'A' being basic poor quality steel for basic components such as handles, spacers etc, and grade 'D' being the best for the likes of slide bars, cross heads etc. The grades in between were anyone's guess). The EN material reference has continued to be in use from that time. Many attempts have been made to update and circulate a new EN standard, but the original designation tends to remain in the British engineering workplace.

One can only generalise the structure of the EN system without producing a chemical make-up chart that details the complete steel composition. The designations can therefore be generalised as follows:

The higher the EN number, generally the better the properties of the steel.

EN1 to EN3 - Low carbon and basic purpose steel.(modern EN3 is EN32 in round form)

EN5 to EN16 - Medium carbon with good general strength properties.

EN19 to EN24 - High carbon steels with good hardenability.

EN32 to EN36 - Case hardening/heat treatable steel for improved wear properties.

EN40 to EN45 - Spring steels, properties improve dramatically from heat treating.

EN56 to EN60 - Stainless steels.

A further letter is often added to the designation to indicate a state of heat treatment or free cutting additives (such as PB for increased lead content)

The second most common material designation used in the UK is probably the BS970 standard - although officially this has been superseded by another european standard, confusingly also named the 'BS EN' number. The BS970 standard however was designed to clearly detail the carbon content and the specific type of steel via the numbers and letter given to the material as shown below.

What do EN and BS970 actually mean?

STEEL TYPE: This three digit number indicates the makeup of the steel, it uses this numerical order:

000 to 199 - Carbon Manganese steel, number indicates the steel type.

200 to 240 - Carbon Manganese steel grades that are classed as free cutting.

250 to 260 - Silicon Manganese spring steels.

300 to 499 - Stainless steel and steels that are heat resistant.

500 to 999 - Alloyed steel.

LETTER: The single letter will be one of four designations, A,H, M or S

A - The steel is supplied to a chemical composition as part of a batch. Mass produced and not individually tested.

H - This specification means that the steel is suitable for hardening.

M - Essentially the same as the 'A' specification but each bar has been mechanically tested and certified to match the desired chemical composition.

S - Stainless steel grade.

CARBON CONTENT: The last two numbers represent the average material carbon content.

As an example: 080M40 would be Carbon Manganese Steel, mechanically tested and certified to match the chemical composition with a carbon content of 0.40% (values are averages and nest within a manufacturing tolerance). Another example would be 080A15 which is the same Carbon Manganese Steel, supplied as an untested batch to a chemical formula and with 0.15% carbon content. The first example is EN8, the second is EN3B/EN32B. Both are s similar material but EN8 contains 0.25% more carbon which greatly adds to the hardenability and other mechanical advantages.

Want to ask a question?

If you want to place and order then the quickest way is to either telephone or email, currently we don't take orders on-line as we're old fasioned and like to write things down (this way we know if we have physical material stock on our shelves for an enquiry.) We're always available to help with a material selection or advise on an engineered part, please feel free to give us a call as one of our engineers will be happy to help.

Get in touch»


We're a small business trading under the name of M-Machine, our registered company name is Craftgrange Limited. We operate from the UK under the registration number of 01476185 and were established in 1980 to supply pressed steel panels, engineered parts and materials to business and general public.

Learn more about who we are »


Unit 3 to 7 Forge Way, Cleveland Trading Estate
Darlington, County Durham, DL1 2PJ. UK
P: (01325)381302 (Metals and Engineering)
P: (01325)381300 (Mini Pressings and Accounts)
E: Get in touch via e-mail


What3Words Location: recent.guards.cover