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EN8 (080M40 / 080A42)

Medium Carbon Steel

EN8 Bright & Black Bar

EN8 is a medium carbon steel which is used in applications where better properties than mild steel are required, at a lower cost than an alloy, making this an excellent alternative to alloy.

This is an unalloyed carbon steel with reasonable tensile strength. Heat treating EN8 engineering steel provides a good surface hardness. It can be flame or induction hardened and is a readily machinable steel.

Although EN8 steel is capable of through hardening by quenching and tempering, it is more commonly supplied in the untreated or normalised condition. It possesses good wear resistance, but reduced weldability.

Heat treatment of EN8 steel

When heat treated, EN8 offers moderate wear resistance. It shares the same good mechanical properties of EN16 | 605M36T steel which is more resistant to shear loading and frictional wearing. EN8 can be tempered at a heat of between 550 °C to 660 °C, heating for about 1 hour for every inch of thickness before being cooled in oil or water. Normalising of EN8 bright Mild Steel takes place at 830-860 °C.

Did you know C45 / C40 are European steel grades offering similar characteristics and suitable for similar applications as EN8?

In conclusion, EN8 steel is suitable for all general engineering applications requiring a higher strength than mild steel. If you are unsure about which is the right steel for a specific application, call 01457 866911 and talk to one of our expert Sales Team.

Stock range

High Peak Steels stock EN8 round bar, EN8 flat bar and EN8 square bar.

Associated standards

UK Standard EN8 | European Grades C40 / C45 | Werkstoff 1.0511 | SAE/AISI 1040

EN8 availability

EN8 PRICES & STOCK

Typical Applications

  • AUTOMOTIVE PARTS
  • CONNECTING RODS
  • STUDS, BOLTS
  • AXLES, SPINDLES
  • GENERAL ENGINEERING COMPONENTS

An in-depth analysis of EN8 carbon steel

Mark Thornley, Managing Director of High Peak Steels, shares his extensive knowledge and experience with a question and answer session on EN8 steel…

What is it about EN8 steel that makes it so popular with your engineering customers?

En8 / 080M40, or C45 as it’s commonly known, is a medium carbon steel, whereas mild steel is a 20 carbon steel. It can be supplied in bright drawn condition, black as rolled or normalised. We stock EN8 from 1/4″ (6mm) diameter to as big as 800 mm diameter and it is normally on the shelf ready to be supplied in random lengths or cut pieces. There is not a lot of difference in price between mild steel and EN8 in rounds, therefore engineers prefer the better properties they get with EN8 and don’t have to pay a whole lot more.

Can you tell me a little about the properties of the EN8 steel grade?

It’s a medium carbon steel, normally >40->45 %. It has a 40 tons tensile strength, it machines well, it can be heat treated (flame or induction hardened), it is suitable for most general engineering applications requiring a higher strength than mild steel.

It is the preferred choice of engineers for being able to offer a higher tensile strength in requirements like axles, gears and shafts which require good wearability.

Is it an expensive material compared to other grades?

EN8 represents great value in comparison to alloy engineering steels – probably 50% cheaper – but it still produces a good tensile strength along with good wearability so it has become one of the most popular steel grades to use for economic reasons.

What are the applications your engineering customers will typically use EN8 for?

In construction it will be used for buildings, bridges, and heavy duty equipment. In the oil & gas industry it will be used for parts in pressure vessels. In automation and heavy machinery it will be used for gears, shafts, axles, excavation arms in the likes of JCB’s, so we sell a lot into the yellow goods markets.

Are there situations when you’d heat treat EN8 steel?

So, you can anneal EN8, flame harden, or heat treat to obtain a desired tensile strength and hardness. Most of the the EN8 we supply will come in the as drawn state, if its bright bar. If it’s black bar, then its either in the as-rolled or normalised condition.
The reason for heat treatment would be to refine the microstructure or harden the material to obtain the required yield or tensile strength. By heat treating and refining the material you then get a steel with fewer hard spots and so easier to machine, which helps save costs.

A lot of customers will buy the material in a softened state (normalised). They will pre-machine their parts, then send for hardening before they finish machine their components. This reduces the machining costs by working on the softer material before completion.

What about EN8's wear resistance?

It offers good wearability. What you get with EN8 is a low cost steel that has good machinability, is heat treatable, possesses decent tensile strength, doesn’t wear out easily and has a great size range and availability. So, a very good practical choice for a lot of different applications.

Why are there different names or grades for EN8 ?

We stock EN8, 080A42, 080M40, C45, Werkstoff 1.0511 | SAE/AISI 1040. We can do this by refining the steel specification we are ordering from the steel mills. We can order material that will conform to the EN8, 080M40, 080A42, C45, and AISI 4140 by restricting and refining the elements, such as the amount of carbon content allowed.

We do stock EN8 free machining steel in grade 212A42 which has added sulphur content to make it free machining, but this normally only comes in bright bar in rounds and hexagons on a limited size range. We get a lot or repetition machine companies that ask for this because of the amount of machining needed on the finished parts.

We also stock Key Steel in EN8, normally produced in flat and square sizes and in bright bar condition, but with a limited size range available. This material is used to maintain the driving torque between couplings, gears, and sprockets and can also be used with moving shafts and pulleys, mechanical drums, and propellers.

What shapes and sizes of EN8 are available from High Peak Steels?

Black rounds: 25mm diameter – 800mm diameter (supplied in cut pieces or full bars).
Bright rounds: 6mm diameter – 200mm diameter, in both metric and imperial sizes.
Flat and square bar, mainly in bright condition but limited size ranges available.
Hexagons in EN8 normally come in the free machining grade 212A42 with the added sulphur for easy machining and limited size range up to 55mm a/f.

EN8 | 080M40 Steel size ranges

Cross sectionProductMin sizeMax size
codes-round2 EN8 round bar25mm dia800mm dia
codes-flat2EN8 flat bar
codes-square2EN8 square bar75mm200mm Billet SQ
codes-hex2EN8 hex bar

EN8 | 080M40 Chemical Composition

CSiMnSPCrNiMo
Min0.360.10.6
Max0.440.410.050.050.30.40.15

EN8 | 080M40 Mechanical Composition

Yield
N/mm2		0.2% proof
N/mm2		UTS (Rm)
N/mm2		Elong (A)
%		Red of Area (Z)
%		Hardness
HB		Impact Test (KV)
J
Normalised (min)2805501615216
Normalised (max)207
Drawn (min)5106508
Drawn (max)
Quenched & Tempered to condition Q (min)3856251617928
Quenched & Tempered to condition Q (max)229

EN8 | 080A42 Steel size ranges

Cross sectionProductMetric sizes
Min		MaxImperial sizes
Min		Max
codes-round2EN8 round bar5mm dia200mm dia1/4" dia8" dia
codes-flat2EN8 flat bar8mm x 7mm Key Steel50mm x 28mm Key Steel5/16" x 1/4" Key Steel2" x 1 1/2" Key Steel
codes-square2EN8 square bar4mm SQ Key Steel50mm SQ Key Steel3/16" SQ Key Steel2" SQ Key Steel
codes-hex2EN8 hex bar

EN8 | 080A42 Chemical Composition

CSiMnSPCrNiMo
Min0.40.10.7
Max0.450.40.90.050.050.30.40.15

For more information on EN8 medium carbon steel Please get in touch

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