Introduction
EN36C is a high-quality case-hardening alloy steel known for its exceptional core toughness, high surface hardness, and excellent wear resistance after carburizing and hardening. It is widely used in the manufacture of heavily stressed components where high surface durability and core strength are essential. EN36C is particularly effective for producing components subject to high load, wear, and fatigue.
Properties of the Grade:
- Excellent case-hardening characteristics.
- High surface hardness (up to 62 HRC) after carburizing.
- Superior core strength and toughness.
- Excellent fatigue resistance and dimensional stability.
- Suitable for shock and heavy-duty applications.
- Good machinability in annealed condition.
Uses/Applications of the Grade:
EN36C is ideal for parts that require a tough core and hard surface, commonly used in:
- Gears and gear shafts
- Crankshafts
- Camshafts
- Connecting rods
- Transmission parts
- Pinions
- Heavy-duty machine components
- Aircraft and automotive components subjected to high loads and stresses
Chemical Composition:
| Element | Content (%) |
| Carbon (C) | 0.12 – 0.18 |
| Silicon (Si) | 0.10 – 0.35 |
| Manganese (Mn) | 0.40 – 0.70 |
| Chromium (Cr) | 3.00 – 3.75 |
| Nickel (Ni) | 3.00 – 3.75 |
| Sulfur (S) | ≤ 0.035 |
| Phosphorus (P) | ≤ 0.035 |
| Iron (Fe) | Balance |
Mechanical Properties:
| Property | Value |
| Tensile Strength (core) | 850 – 1000 MPa |
| Yield Strength (core) | ~650 MPa |
| Elongation (in 50 mm) | 13 – 15% |
| Impact Strength (Izod) | 50 – 70 J |
| Hardness (Case) | Up to 60 – 62 HRC |
| Hardness (Core) | ~250 – 300 HB |
Physical Properties:
| Property | Value |
| Density | ~7.85 g/cm³ |
| Modulus of Elasticity | ~210 GPa |
| Thermal Conductivity | ~46 W/m·K |
| Coefficient of Thermal Expansion | 11.7 x 10⁻⁶ /°C |
| Specific Heat Capacity | ~460 J/kg·K |
| Electrical Resistivity | ~0.16 µΩ•m |
Forging:
Forging
- Forging Temperature Range: 1050°C – 1200°C
- Do not forge below 850°C
- Cool slowly in sand or furnace
- Post-forging annealing is recommended to relieve internal stresses
Heat Treatment:
Annealing
- Temperature: 640°C – 680°C
- Cool in furnace
- Reduces hardness and improves machinability
Carburizing:
- Temperature: 880°C – 940°C
- Carburizing depth: 0.5 – 2.0 mm depending on component
- Followed by quenching in oil
Hardening (after carburizing):
- Temperature: 770°C – 820°C
- Quench in oil or water
- Achieves surface hardness of 60 – 62 HRC
Tempering:
- Temperature: 150°C – 200°C
- Purpose: Relieve internal stress and increase toughness
- Avoid over-tempering to retain surface hardness
Dimensional Tolerances:
- Available as per DIN, BS, or customer-specific tolerances
- Supplied in hot rolled, peeled, or ground finish
- Bars available in diameters from 10 mm to 300 mm
- Standard length: 3 to 6 meters, or custom on request
Corrosion Resistance:
- EN36C does not possess stainless properties
- It must be coated, plated, or oiled for protection in corrosive environments
- Not recommended for marine or highly corrosive conditions without protective treatment
Machinability:
- Good machinability in annealed condition
- Use carbide tools for longer tool life
- Ensure proper coolant/lubrication for smoother finish and accuracy
- Machinability decreases after hardening due to high surface hardness
Weldability:
- Weldability is limited due to high alloy content and case-hardening nature
- Preheating to 250°C – 350°C is essential before welding
- Post-weld heat treatment is necessary to restore properties
- Welding is not recommended on hardened material
Available Form:
- Round Bars (Hot Rolled, Peeled, or Ground)
- Forged Bars / Blocks
- Bright Bars
- Custom Cut Lengths
- Available in annealed or hardened + tempered conditions
Conclusion:
EN36C alloy steel is a premium case-hardening steel widely used for producing high-performance components exposed to wear, stress, and fatigue. With its ability to attain a hard, wear-resistant surface while maintaining a tough, shock-absorbing core, EN36C is ideal for automotive, aerospace, and heavy engineering industries. When properly heat-treated and machined, it delivers exceptional durability and long service life.
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