Carbon Steel En9
EN9 is a medium carbon steel that offers high tensile strength and good wear resistance. It contains a slightly higher carbon content than EN8, which allows it to achieve greater hardness and strength after heat treatment. EN9 is commonly supplied in the rolled or normalized condition and can be flame or induction hardened for improved surface wear resistance.
This steel is widely used for making machine parts, shafts, gears, crankshafts, spindles, and high-stress components where strength and durability are essential. EN9 provides a good balance between toughness, strength, and machinability, making it a popular choice in both automotive and general engineering industries.
Applications
Used for shafts, axles, spindles, and studs where strength and wear resistance are required.
Commonly used in automotive parts like gears, crankshafts, and connecting rods.
Ideal for machine tools and industrial rollers due to its hardness and toughness.
Applied in hammers, knives, and hand tools where durability is essential.
Suitable for press tools, cams, and sprockets that undergo repetitive stress.
Used in agricultural machinery and construction equipment parts.
Chemical Composition
| Element | Carbon (C) | Manganese (Mn) | Silicon (Si) | Sulphur (S) | Phosphorus (P) | Iron (Fe) |
|---|---|---|---|---|---|---|
| Percentage (%) | 0.50 – 0.60 | 0.50 – 0.80 | 0.05 – 0.35 | 0.05 max | 0.05 max | Balance |
Hardness
Annealed condition: Approximately 200–250 HB (Brinell Hardness).
Hardened condition: Can reach up to 600–650 HV (around 55–60 HRC) after proper heat treatment and tempering.
The hardness varies based on the quenching medium and tempering temperature used.
Equivalent Grades
- BS (British Standard) EN9
- AISI / SAE (USA) 1050
- DIN (Germany) C50E / CK50
- JIS (Japan) S50C
- IS (India) C55 / 070M55
- UNS G10500
Heat Treatment
Annealing:
Heat slowly to 680–710°C, then cool slowly in the furnace.
This process softens the steel and relieves internal stresses.
Normalizing:
Heat to 840–870°C, then cool in still air.
Normalizing refines the grain structure and improves toughness.
Hardening:
Heat to 800–830°C, hold until uniform temperature is reached.
Quench rapidly in oil or water to achieve maximum hardness.
Tempering:
After hardening, temper at 150–200°C for desired toughness and to reduce brittleness.
Higher tempering temperatures (up to 400°C) may be used based on required mechanical properties.
Hardening
Process:
The steel is heated uniformly to 820–850°C, then quenched in oil or water depending on the desired hardness and application.
Tempering:
After hardening, the steel is tempered at 150–200°C to reduce brittleness and relieve internal stresses while retaining good hardness.
Resulting Hardness:
After proper hardening and tempering, EN9 typically achieves a hardness of around 50–55 HRC.
Welding
Preheating:
Preheat the material to around 150–250°C before welding to reduce the risk of cracking.
Filler Material:
Use low-hydrogen electrodes such as E7018 for better results.
Post-Weld Heat Treatment (PWHT):
After welding, stress relieving at 550–650°C is recommended to minimize residual stresses and improve ductility.
General Note:
EN9 should ideally be machined or formed rather than welded, especially for critical or load-bearing components.
Machinability
EN9 exhibits good machinability in both normalized and annealed conditions. Its medium carbon content provides a balance between strength and ease of cutting.
Machining Condition:
Best machinability is achieved when the steel is normalized or softened before machining.
Tool Recommendation:
High-speed steel (HSS) or carbide-tipped cutting tools are commonly used.
Surface Finish:
EN9 produces a smooth surface finish under proper cutting speeds and lubrication.
Machinability Rating:
Approximately 55–60% compared to mild steel (based on machinability index).
Lubrication:
Use cutting oil or coolant to prevent tool wear and overheating.
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1460–1500°C |
| Elastic Modulus | 210 GPa |
| Thermal Conductivity | 46.6 W/m·K at 100°C |
| Electrical Resistivity | 0.0000168 Ω·m at 20°C |
| Specific Heat Capacity | 480 J/kg·K |
| Poisson’s Ratio | 0.27–0.30 |
| Magnetic Properties | Magnetic |
Chemical Properties
| Property | Value |
|---|---|
| Corrosion Resistance | Moderate; can be improved with proper surface coatings or treatments. |
| Hardness | 200–250 HB (Annealed) and up to 55 HRC (Hardened). |
| Tensile Strength | High — typically ranges from 600–850 MPa after heat treatment. |
| Toughness | Excellent when properly tempered. |
| Wear Resistance | Good, suitable for parts exposed to friction and load. |
| Machinability | Good in annealed condition; becomes difficult when hardened. |
| Thermal Stability | Maintains mechanical strength at moderate temperatures. |
Dealer
We are a leading dealer, supplier, stockist, and trader of Carbon Steel EN9, offering high-quality material in various forms such as round bars, flat bars, plates, and sheets.
Our EN9 products are sourced from reliable manufacturers and are available in both black and bright finishes, ensuring superior performance in mechanical and structural applications.