EN8 Carbon Steel: Composition, Strength, and Equivalent Grades Explained

by AMC

Posted on May 30, 2024 at 03:30 PM

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What is EN 8 Carbon Steel?

EN8 carbon steel is a type of medium carbon and medium tensile steel that offers improved strength compared to mild steel. It is characterized by its ability to be through-hardened, making it suitable for applications requiring enhanced durability. EN8 carbon steel is also known for its machinability in various conditions.

Typically, EN8 steels are used in their untreated condition. However, they can be surface-hardened using induction processes, resulting in components with increased wear resistance. When heat treated, EN8 steel exhibits consistent machining properties due to its homogenous metallurgical structures.

For sections larger than 65mm, good heat treatment results can still be achieved, although there may be a decline in mechanical properties towards the center of the bar. Therefore, it is recommended to supply larger sizes of EN8 steel in the untreated condition and perform any necessary heat treatment after initial stock removal. This approach can lead to improved mechanical properties closer to the core of the material.

EN8 medium-strength carbon steel, classified under the British standard BS970 as 080M40, is also known as Steel Grade 40. This steel is widely used in engineering and construction applications due to its structural strength. It is recognized by various names globally, including C45 in the EU, 1040 steel in the USA, 45 in China, S40C in Japan, and ISO68318.

Compared to bright mild steel, EN8 exhibits superior tensile strength, thanks to the thermo-mechanical rolling process during its production. This makes EN8 a preferred choice for applications that require stronger properties than mild steel, offering a cost-effective solution without compromising on performance.

EN8 Steel is Steel Grade in BS 970 1955 Specification

EN8 steel is indeed a steel grade specified in the BS 970-1955 standard, which covers wrought steel for mechanical and allied engineering purposes. This standard includes several other common steel grades such as EN9, EN19, EN24, EN36, among others.

The equivalent grade to EN8 in the BS 970-1991 standard is typically referred to as 080M40 steel.

EN8 Steel Chemical Composition

Element Content (%)
C 0.36-0.44
Mn 0.60-1.00
Si 0.05-0.35
P 0.015-0.06
S 0.015-0.06

EN8 Medium Carbon Steel Mechanical Properties and Hardness

Heat Treatment Tensile Strength Rm Yield Strength
Rp 0.2 A min on Impact Hardness
5.65√So Izod Ft.lb KCV J
MPa MPa MPa       HB
N 550 280 16 15 16 152/207
510 245 17 146/197
Q 625/775 385 355 16 25 28 179/229
R 700/850 465 450 16 25 28 201/255

EN8 Carbon Steel Equivalents Grade

Here are the equivalents of EN8 carbon steel grade in various standards:

  • BS 970-1991: 080M40
  • AISI/ASTM A29: 1038, 1040, 1045
  • DIN Werkstoff No.: 1.0511, 1.1186, 1.1189
  • BS & DIN European: C40, CK40, C45, CK45
  • JIS G4051: S40C, S45C

Forging of Carbon Steel Grade EN8/080M40

  • Preheat the EN8 steel carefully and raise the temperature to 1050°C for forging.
  • Do not forge below 850°C.
  • After forging, cool the EN8 steel slowly, preferably in a furnace.

Heat Treatment of EN8 Carbon Steel

  • EN8 steel is typically supplied untreated but can be supplied to order in normalized or finally heat-treated conditions, suitable for a wide range of applications.
  • Tempering: Carbon steel EN8 or 080M40 can be tempered at a heat of between 550°C to 660°C (1022°F-1220°F). Heat for about 1 hour for every inch of thickness, then cool in oil or water.
  • Normalizing: EN8 bright mild steel normalizes at 830-860°C (1526°F-1580°F), followed by cooling in air.
  • Quenching: Quenching in oil or water after heating to the specified temperature will harden the steel.

EN8 Carbon Steel Density

EN8 Carbon Steel Density is around 7.8 g/cm³. This high density contributes to its overall strength and durability.

Thermal Conductivity

EN 8 has decent thermal conductivity, allowing it to transfer heat reasonably well. This can be an advantage or a disadvantage, depending on your application.

Applications of EN 8 Steel

With its impressive properties, it's no wonder EN 8 carbon steel is used in countless applications across various industries.

Shafts and Axles

One of the most common uses of EN 8 is in the production of shafts and axles. Its strength and wear resistance make it perfect for these high-stress, high-load components found in everything from cars to industrial machinery.

Gears and Bearings

Similarly, EN 8 is a popular choice for gears and bearings. Its hardness helps prevent excessive wear, while its strength ensures these crucial components can withstand the forces they're subjected to.

Other Common Uses

But that's just the tip of the iceberg! You'll also find EN 8 in various tools, fasteners, hydraulic components, and even some structural applications. Its versatility is one of its biggest assets.

Manufacturing EN 8

So, how do we get our hands on this awesome alloy? There are two main production methods for EN 8 carbon steel.

Hot Rolled Process

One method is hot rolling, where the steel is heated and then passed through a series of rollers to shape it into bars, rods, or other forms. This process is great for producing large quantities of material but can result in slightly less precise dimensions and surface finishes.

Cold Finished Process

For tighter tolerances and smoother surfaces, manufacturers often opt for the cold finished process. Here, the hot-rolled steel is further processed while cold, using techniques like drawing, grinding, or turning to achieve the desired size and finish.

Where to Buy EN 8 Steel

If you're looking to purchase EN 8 carbon steel bars, rods, plates, or other forms, you're in luck! EN 8 steel is widely available at Amardeep Steel. We are a leading supplier & exporter of EN 8 carbon steel around the world.

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