What is EN8 Steel

When looking for the right material, it is crucial to break down its composition to understand its strengths and applications. Identifying a material’s qualities—such as EN8 steel’s medium-carbon structure—enables you to choose the best fit for your needs, especially when comparing similar steels like EN9. In this guide, we’ll explore EN8 steel’s properties, uses, and how it compares to EN9 to help you make an informed decision.
What is EN8 Steel

EN8 is a medium-carbon steel recognized for its balance of strength, toughness, and affordability. Composed of approximately 0.36–0.44% carbon, EN8 steel achieves a moderate tensile strength ideal for parts that require durability and machinability. Known in various standards, such as BS970 (080M40) and C45 in Europe, EN8’s versatility makes it popular in automotive, engineering, and manufacturing industries.
What is EN8 Steel Used For
EN8’s mechanical properties lend it to a wide range of uses, particularly in parts subjected to wear and moderate stress:
- Automotive Parts: Used in components like connecting rods, crankshafts, axles, and spindles that demand strength and resilience.
- Engineering and Construction: Found in parts requiring durability, including bolts, shafts, studs, and machine components.
- Agricultural Equipment: Provides durability in plowshares, cultivator blades, and heavy-duty tools.
- Tool Manufacturing: Used in the production of paint scrapers, wrenches, and general hardware.
Chemical Composition of EN8
EN8’s chemical composition focuses primarily on carbon and minimal alloying elements, keeping production cost-effective while enhancing strength and machinability. Here’s how it compares internationally:
Country/Standard | Grade | Carbon (C) | Silicon (Si) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) |
UK – BS970 | EN8 | 0.36–0.44% | ≤ 0.40% | 0.50–0.80% | ≤ 0.045% | ≤ 0.045% |
USA – AISI | 1045 | 0.43–0.50% | ≤ 0.35% | 0.60–0.90% | ≤ 0.04% | ≤ 0.05% |
Japan – JIS | S45C | 0.42–0.50% | 0.15–0.35% | 0.60–0.90% | ≤ 0.03% | ≤ 0.035% |
China – GB | 45 | 0.42–0.50% | 0.17–0.37% | 0.50–0.80% | ≤ 0.035% | ≤ 0.030% |
Mechanical Properties of EN8
EN8’s mechanical properties offer a solid balance of tensile strength and hardness, suitable for components exposed to wear and stress:
- Tensile Strength: 600–700 MPa in normalized condition, with hardened and tempered versions reaching 850–1000 MPa.
- Yield Strength: Starts at 310 MPa, improving with heat treatment.
- Hardness (Brinell): Between 170–255 HB, depending on tempering.
- Elongation: Typically around 12-14%, which reflects its moderate ductility.
Thermal Properties of EN8
EN8 performs well in moderate-temperature applications:
- Thermal Conductivity: 51.9 W/m-K
- Melting Point: Approximately 1425–1540°C
- Specific Heat Capacity: 486 J/kg-K
These properties allow EN8 to handle temperature changes without losing structural integrity, making it suitable for machine parts and tools that may experience fluctuating heat levels.
Global Equivalents of EN8
EN8 has equivalents in several countries, each under their specific standards but maintaining similar properties. Here’s a quick look at these equivalents:
Country | Standard | Grade |
China | GB | 45 |
Japan | JIS | S45C |
USA | AISI | 1045 |
France | AFNOR | XC45 |
Italy | UNI | C45 |
Germany | DIN | Ck45 |
Russia | GOST | 45 |
Heat Treatment of EN8
EN8’s performance can be optimized through heat treatment processes to adjust its hardness, strength, and ductility:
- Annealing: Conducted at 850-900°C, then cooled to reduce hardness and internal stress.
- Normalizing: Heats to 830-860°C, air-cooled to refine grain structure, enhancing toughness and machinability.
- Hardening: Heated to 820-860°C and quenched, typically in oil or water, to achieve a hard, wear-resistant surface.
- Tempering: Performed between 550-660°C after hardening to relieve stress and improve toughness.
These treatments adjust EN8’s mechanical properties to meet the demands of specific applications.
Advantages and Disadvantages of EN8 Steel
Welding: Requires preheating to reduce brittleness. Post-weld heat treatment can also alleviate stress.
Machining: Coated carbide tools are best for machining; adequate cooling extends tool life and ensures precision.
Storage: Allow stabilization time post-machining to relieve internal stress, promoting consistency in mechanical performance.
Advantages and Disadvantages of C45 Steel
Advantages:
- High Strength and Toughness: Suitable for applications under mechanical stress.
- Affordable: Its production is cost-effective, making it a popular choice for medium-duty components.
- Easy Machinability: Can be easily shaped, drilled, and turned in its normalized state.
Disadvantages:
- Limited Corrosion Resistance: Requires coatings or treatments in corrosive environments.
- Brittleness in the Welded State: Needs preheating and post-weld treatment to prevent cracking.
- Temperature Limitations: Loses mechanical strength at high temperatures.
The Difference Between EN8 and EN9 Steel
While EN8 and EN9 are medium-carbon steels with similar applications, EN9 has a slightly higher carbon content, contributing to higher tensile strength but with reduced ductility. Here are the main differences:
- Carbon Content: EN9 typically has 0.50-0.60% carbon, compared to EN8’s 0.36-0.44%.
- Tensile Strength: EN9 achieves slightly higher tensile strength, making it better for high-stress applications.
- Applications: Both are used in automotive and general engineering, but EN9 may be favored where higher wear resistance is required.
Conclusion
EN8 steel is a versatile, medium-carbon steel with balanced mechanical properties, suitable for a range of industrial applications. Its strength, affordability, and ability to undergo various heat treatments make it a staple in automotive, construction, and machinery sectors. Understanding its properties and treatment options, along with comparing it to similar grades like EN9, allows users to select the best material for their specific needs.
For more tailored solutions, ZGT Special Steel provides high-quality EN8 steel with customized processing options to meet diverse application requirements. Contact us for expert advice and industry-grade materials designed for optimal performance in demanding environments.
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