What is C45 Steel?
C45 steel, known for its medium carbon content and balanced properties, is a go-to material for applications requiring moderate strength and machinability. Used globally, it’s recognized under various standards: EN 10083 in Europe, AISI 1045 in the US, and S45C in Japan. With a composition that lends itself well to heat treatment, C45 steel serves in automotive, construction, and machinery industries, where durability, moderate wear resistance, and machinability are valued. This guide explores its characteristics, applications, types, and global equivalents.
What is C45 Steel
C45 steel is a medium-carbon steel known for its strength, durability, and versatility across various industrial sectors. Commonly categorized under standards like EN 10083, DIN, and GB, it’s referred to as AISI 1045 in the US and S45C in Japan. With a carbon content of approximately 0.42–0.50%, C45 provides a balanced mix of hardness and toughness, making it ideal for applications requiring moderate strength.
Key Points:
- Standard Designations: Known as EN 10083 C45 in Europe, AISI 1045 in the US, and S45C in Japan.
- Main Characteristics: Medium carbon content contributes to both strength and machinability.
- Application Scope: Ideal for parts such as gears, shafts, and axles.
Applications of C45 Steel
C45 steel’s mechanical properties make it versatile across industries:
- Automotive Industry: Commonly used for gears, crankshafts, and drive shafts due to its strength.
- Industrial Machinery: Ideal for structural components like bolts, rods, axles, and machinery parts.
- Construction Sector: Used in manufacturing tools and components for hydraulic systems and structural plates.
- Agricultural Equipment: Suitable for heavy-duty tools, including plowshares and cultivator blades.
Types and Forms of C45 Steel
C45 steel is manufactured in various forms depending on its application:
- Hot-Rolled Plates and Sheets: Used in structural applications where precision is less critical.
- Cold-Rolled Bars and Rods: Offer high dimensional accuracy and smooth finishes for machinery components.
- Forged Rounds: Common in automotive parts, especially for gears and crankshafts.
- Quenched and Tempered Forms: Heat-treated to enhance hardness for high-stress applications.
Chemical Composition and Global Equivalents
| Country/Standard | Grade | Carbon (C) | Silicon (Si) | Manganese (Mn) | Phosphorus (P) | Sulfur (S) |
| USA – SAE | 1045 | 0.43-0.50 | ≤0.35 | 0.60-0.90 | ≤0.04 | ≤0.05 |
| China – GB | 45 Steel | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | ≤0.035 | ≤0.030 |
| Japan – JIS | S45C | 0.42-0.50 | 0.15-0.35 | 0.60-0.90 | ≤0.030 | ≤0.035 |
| Europe – EN | C45 | 0.42-0.50 | ≤0.40 | 0.50-0.80 | ≤0.045 | ≤0.045 |
This table demonstrates slight variations in composition across standards, with similar carbon content ensuring comparable properties.
Mechanical Properties of C45 Steel
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| Property | Metric | Imperial |
| Tensile Strength | 570–700 MPa | 82,000–101,000 psi |
| Yield Strength | ~310 MPa | ~45,000 psi |
| Hardness (Brinell) | 170–210 HB | 170–210 HB |
| Elongation at Break | ~16% | ~16% |
Thermal Properties of C45 Steel
C45’s thermal properties contribute to its functionality in temperature-variable environments:
- Thermal Conductivity: 51.9 W/m-K
- Melting Point: ~1425–1540 °C
- Specific Heat Capacity: 486 J/kg-K
Its adaptability in moderate heat environments makes it valuable for machinery parts exposed to temperature changes, though additional protection may be necessary in high-heat settings.
Heat Treatment Processes for C45 Steel
Heat treatment can further enhance C45’s mechanical properties:
- Forging/Hot Rolling: 1100–850°C
- Normalizing: Heats to 840–880°C, then air-cooled to refine grain structure.
- Annealing: Conducted at 680–710°C to improve machinability.
- Hardening and Tempering: Heated between 820–860°C and quenched, then tempered at 550–660°C for increased toughness and hardness.
When heat-treated, C45 is better suited to high-stress applications, making it both versatile and reliable.
Processing Precautions for C45 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 tensile strength and moderate hardness suitable for wear-resistant applications.
- Versatile in forming, welding, and heat treatments.
- Cost-effective and widely available.
Disadvantages:
- Low corrosion resistance, requiring coatings in harsh environments.
- Unsuitable for high-temperature applications, as properties may degrade.
- Brittle heat-affected zones if not properly processed, especially during welding.
Differences Between C45 and 45 Steel
C45 and 45 Steel have similar carbon levels but vary in specifications due to regional standards:
- C45 Steel (DIN/EN): Common in European markets.
- 45 Steel (GB Standard): Frequently used in China for similar applications.
Both options provide balanced strength and durability, though selection often depends on regional availability and standards.
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Conclusion
C45 steel’s strength, toughness, and adaptability make it invaluable across industries, from automotive to construction. When heat-treated, C45 provides reliable wear resistance and durability for demanding applications. However, it’s crucial to consider corrosion resistance and thermal stability to maximize performance.
For customized solutions, ZGT Special Steel offers high-quality C45 steel and processing services, ensuring top durability and performance tailored to your application needs.
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