Description
55Si7 Steel Introduction:
55Si7 is a high-silicon spring steel that is known for its excellent elasticity, resilience, and high tensile strength. Silicon (Si) is the key alloying element in this steel, contributing to its ability to withstand high levels of stress and strain while maintaining its form. 55Si7 is typically used in the production of components that require high fatigue resistance and durability, such as leaf springs and coil springs for automotive and industrial applications. Its strength and ability to retain elasticity under heavy loads make it a preferred material in the spring manufacturing industry.
55Si7 Grade Applications:
55Si7 is commonly used for the production of high-stress components, including:
- Automotive leaf springs
- Coil springs
- Suspension components
- Railway springs
- Springs for industrial machinery
Equivalent Grades:
- DIN: 1.5026 (55Si7)
- EN: 55Si7
- AISI/SAE: Approximate to SAE 9254 (with higher silicon content)
- JIS: SUP6 (similar)
Chemical Composition:
| Element | Content (%) |
|---|---|
| C | 0.52-0.60 |
| Si | 1.50-2.00 |
| Mn | 0.60-0.90 |
| P | ≤ 0.035 |
| S | ≤ 0.035 |
Mechanical Properties:
| Property | Value |
|---|---|
| Tensile strength (MPa) | 1270-1570 |
| Yield strength (MPa) | ≥ 1150 |
| Elongation rate (%) | ≥ 7 |
| Reduction of area (%) | ≥ 30 |
| Hardness (HB) | 320-380 (quenched and tempered) |
55Si7 Hardness:
In the quenched and tempered condition, the hardness of 55Si7 typically ranges from 320 to 380 HB. This high hardness level makes it ideal for applications requiring resistance to wear and deformation under repeated stress.
Heat Treatment:
55Si7 is typically heat-treated to enhance its mechanical properties, including strength and toughness.
Hardening Process:
- Heating for hardening: The material is heated to 830-870°C, followed by quenching in oil or water.
- Tempering: Tempering is carried out at 400-500°C to reduce internal stresses and increase toughness while retaining the desired hardness and strength.
Physical Properties:
| Property | Value |
|---|---|
| Modulus of Elasticity (N/mm²) | 210 × 10³ |
| Density (g/cm³) | 7.85 |
| Thermal Conductivity (W/m.K) | 46.0 |
Thermal Properties:
- Thermal conductivity: 46.0 W/m.K at room temperature.
- Specific heat: 460 J/kg-K.
Forging Properties:
Forging of 55Si7 is usually carried out at temperatures between 1050°C and 850°C. After forging, it should be cooled slowly to avoid internal stresses that could lead to cracking.
Normalizing:
Normalizing is performed by heating the steel to 850-880°C, followed by air cooling. This process refines the grain structure and improves the toughness and mechanical properties of the material.
Annealing:
Annealing of 55Si7 is typically done at 680-720°C, followed by slow cooling. This softens the material and enhances its machinability, making it easier to process before hardening.
Welding:
55Si7 is not highly recommended for welding due to its high carbon and silicon content, which can lead to cracking and other welding-related issues. If welding is required, preheating and post-weld heat treatment may be necessary to avoid defects and ensure the structural integrity of the weld.
Supply Cities:
Mumbai Ahmedabad, Amaravathi, Ambattur, Bangalore, Belgaum, Chennai, Chittoor, Coimbatore, Dindigul, Mysore, Nellore, Hyderabad, Kochi, Mangalore, Tirupur, Tuticorin, Madurai, Andhra Pradesh, Karnataka, Puducherry, Kerala, Tamil Nadu, Telangana, Visakhapatnam, Kochi, Kerala, Hubli-Dharwad, Karnataka, Ghaziabad Kolkata.
