EN8 Carbon Steel

EN8 carbon steel is a medium carbon steel known for its balanced strength and toughness. It offers higher tensile strength compared to mild steel, making it suitable for applications where increased durability is required. EN8 can be through-hardened, allowing it to withstand greater wear and tear, which makes it ideal for components that need to be strong and resilient.

Typically, EN8 is used in its untreated form, but it can be surface-hardened through processes like induction hardening to enhance its wear resistance. When heat-treated, EN8 steel maintains good machinability due to its uniform metallurgical structure. For larger sections, though heat treatment can still be effective, mechanical properties may diminish towards the core, so heat treatment is often recommended after initial machining to optimize these properties.

EN8, classified as 080M40 under the British standard BS970, is also known by various international designations like C45 in Europe and 1040 in the USA. Its combination of strength and cost-effectiveness makes it a popular choice in engineering and construction applications where stronger materials than mild steel are needed without a significant increase in cost.

EN8 Grade

EN8 is a medium carbon steel grade known for its reasonable tensile strength, typically ranging between 500-800 N/mm². It is often supplied in cold-drawn or as-rolled conditions and is ideal for applications requiring better strength than mild steel without the higher cost of alloy steel. EN8 can be flame or induction hardened for improved surface hardness and moderate wear resistance. Available in bar stock and as flame-cut plates, EN8 can be customized to specific sizes and supplied with surface or precision grinding as needed.

EN8 Steel is Steel Grade in 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.

Chemical composition of EN8

EN8 Mechanical Properties

Chemical Composition of Stainless Steel 316 Grade

EN8 Carbon Steel Equivalents Grade

EN8 carbon steel has several equivalent grades across different international 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

These equivalents reflect the similar chemical composition and mechanical properties of EN8 steel across various global standards.

Application of EN8 Grade

EN8 Hardness

Hardness Range: HB 152 – 255

EN8 Heat Treatment

The heat treatment process for EN8 steel involves varying temperatures, heating rates, cooling methods, and soaking times depending on the shape and size of the component. Factors such as the type of furnace, quenching medium, and workpiece transfer also play a significant role in determining the effectiveness of the heat treatment.

EN8 Hardening

To harden EN8 steel, heat the component slowly to a temperature between 820-860°C, ensuring it is evenly heated. After reaching the desired temperature, quench the component in oil or water.

EN8 Tempering

After quenching, temper the EN8 component while it is still hand warm. Reheat the component to the tempering temperature and maintain this temperature for one hour per 25 millimeters of total thickness, with a minimum soaking time of 2 hours. Allow the component to cool in air. For most applications, tempering is typically done at temperatures between 550-660°C.

EN8 Thermal Properties

EN8 Forging Properties

For forging EN8 steel, start by preheating the material carefully. Then, heat it to a temperature of around 1050°C for forging. Avoid forging below 850°C to ensure optimal material properties. After forging, allow the steel to cool slowly, preferably in a furnace, to avoid potential issues with internal stresses.

EN8 Stress Relieving

Stress relieving is a heat treatment process designed to reduce internal residual stresses generated during previous manufacturing processes such as machining, cold rolling, and welding. These stresses can lead to problems like distortion or stress corrosion cracking if not properly addressed.

There are two main stress-relieving methods for carbon and alloy steels:

1. Low-Temperature Stress Relieving (150-200°C): This method is used to relieve peak stresses without significantly reducing the hardness of the material. It’s suitable for case-hardened components and bearings.
2. High-Temperature Stress Relieving (600-680°C): Applied after processes like welding or machining, this treatment provides nearly complete stress relief and is suitable for removing residual stresses effectively.

For non-ferrous alloys, stress relief temperatures vary based on the alloy type and condition. Age-hardened alloys should be stress relieved below their aging temperatures to avoid compromising their properties. Austenitic stainless steels are stress relieved either below 480°C or above 900°C, with treatments in between potentially reducing corrosion resistance in grades that are not stabilized or low-carbon.

EN8 Normalizing

For normalizing EN8 steel, first preheat the material carefully. Raise the temperature to around 1050°C. After reaching this temperature, allow the steel to cool slowly, preferably in a furnace, to achieve a uniform microstructure and reduce residual stresses.

EN8 Density and Mechanical Properties

• Density: 7800 kg/m³
• Young’s Modulus: 190 GPa
• Poisson’s Ratio: 0.3

EN8 Machinability

EN8 steel offers good machinability, which makes it suitable for various engineering applications. The machinability can vary depending on the heat treatment and specific processing methods used.

 EN8 Welding

Modern EN8 steel, which has a lower carbon content compared to older versions, can be welded using MIG wire (SG2) or a 7018 electrode. For pieces up to 18mm thick, preheating is not required. However, for thicknesses over 18mm, preheat the steel to 100°C (212°F) to prevent cracking. After welding, annealing is recommended to reduce the risk of breaking and to relieve internal stresses.

Summary of EN8 Carbon Steel

EN8 is a medium carbon steel known for its good tensile strength and machinability, making it suitable for various engineering applications. It is commonly used in its cold-drawn or as-rolled states and can be flame or induction hardened to enhance surface hardness. EN8 is versatile in applications such as axles, shafts, gears, and bolts.

The steel can be heat-treated by heating to 820-860°C and quenching in oil or water. After quenching, tempering at 550-660°C is recommended to reduce brittleness. EN8 has a density of 7800 kg/m³ and offers good machinability and welding properties. For welding, pieces up to 18mm thick can be welded without preheating, but thicker sections require preheating to avoid cracking. Normalizing and annealing processes are used to achieve desired properties and relieve internal stresses.

EN8 is equivalent to several standards globally, including BS 970-1991: 080M40 and AISI/ASTM A29: 1038, 1040, and 1045, making it a widely recognized and adaptable material in the steel industry.

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