EN43B Carbon Steel Round Bar (UNS G10430)
EN43B Round Bar is a high carbon spring steel grade designed for applications requiring high tensile strength, excellent fatigue resistance, and toughness. Internationally identified as UNS G10430, EN43B contains higher carbon and silicon levels, which enhance its elastic limit and resilience. It is commonly supplied in hot rolled or annealed condition and is widely used in spring manufacturing and dynamic load applications.
Key Features
- High tensile strength and excellent fatigue resistance
- Superior elastic and resilience properties
- Good wear resistance
- Excellent response to heat treatment
- Reliable performance under cyclic and dynamic loads
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| BS | EN43B |
| EN | 55Si7 / 1.5026 |
| DIN | 55Si7 |
| ASTM / SAE | 9255 |
| JIS | SUP7 |
| IS | 55Si7 |
Sizes
- Diameter: 8 mm to 200 mm
- Length: 3 m, 6 m, or cut-to-length
- Custom sizes available on request
EN43B Round Bar Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.52 – 0.60 |
| Silicon (Si) | 1.50 – 2.00 |
| Manganese (Mn) | 0.60 – 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.040 |
EN43B Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 850 – 1000 MPa |
| Yield Strength | ≥ 700 MPa |
| Elongation | ≥ 8% |
| Hardness | 240 – 300 HB |
UNS G10430 Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | ~1450°C |
| Thermal Conductivity | 46 W/m·K |
| Modulus of Elasticity | 210 GPa |
Types
- Hot Rolled Round Bar
- Annealed Round Bar
- Bright Drawn Round Bar
- Heat Treated Round Bar
Applications
- Leaf and coil springs
- Automotive suspension components
- Railway and industrial springs
- Agricultural and earthmoving equipment parts
- High-stress mechanical components





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