C45 Carbon Steel: Non-Alloy Quality Steels (EN 10083 Series)
C45 carbon steel, designated under the EN 10083 series for non-alloy quality steels (equivalent to AISI 1045 or SAE 1045), is a medium-carbon steel renowned for its excellent balance of strength, toughness, and machinability. With a carbon content of 0.42-0.50%, it offers superior wear resistance and is widely used in mechanical engineering after appropriate heat treatment. This article explores its chemical composition, mechanical properties, manufacturing processes, applications, and key considerations for optimal use in industrial settings.
1. Core Chemical Composition (EN 10083-2 Standard)
| Element | Content Range | Function |
|---|---|---|
| Carbon (C) | 0.42 – 0.50% | Provides hardenability and strength; enables quenching to achieve high hardness |
| Silicon (Si) | ≤ 0.40% | Acts as a deoxidizer; enhances strength and elasticity without brittleness |
| Manganese (Mn) | 0.50 – 0.80% | Improves hot workability and tensile strength; counters sulfur effects |
| Phosphorus (P) | ≤ 0.045% | Controlled impurity; higher levels increase brittleness and reduce ductility |
| Sulfur (S) | ≤ 0.045% | Limited for free-cutting variants; in standard C45, minimized to prevent hot shortness |
| Chromium (Cr) | ≤ 0.40% | Residual element; minor contribution to hardenability if present |
2. Key Mechanical Properties (Normalized or Quenched & Tempered Condition)
- Tensile Strength (Rm): 600 – 850 MPa (varies with heat treatment; higher after quenching and tempering)
- Yield Strength (Re): ≥ 355 MPa (minimum for diameters ≤ 100 mm in normalized state)
- Elongation (A): ≥ 16% (good ductility for forming and machining)
- Hardness (HB): 170 – 210 (as-rolled; up to 250 HB after quenching)
- Impact Toughness (KV): ≥ 35 J at room temperature (ensures toughness for dynamic loads)
3. Manufacturing Process Characteristics
- Steelmaking: Basic oxygen furnace (BOF) or electric arc furnace (EAF) followed by ladle refining for low impurity levels and precise chemistry control.
- Hot Working: Forging or rolling at 850-1200°C to produce bars, billets, or plates; final hot finish above 850°C to maintain uniform microstructure.
- Heat Treatment: Normalizing at 870-920°C followed by air cooling; quenching in oil/water at 820-860°C and tempering at 550-650°C for desired hardness and toughness.
- Cold Working: Cold drawing for precision bars (up to 20% reduction); annealing at 650-700°C to relieve stresses and improve machinability.
- Surface Treatment: Shot blasting or pickling to remove scale; optional phosphating or coating for corrosion protection during storage.
4. Typical Application Fields
Mechanical Components
Gears, shafts, pins, and axles in automotive and machinery — heat-treated for wear resistance and fatigue strength under moderate loads.
Tools & Fasteners
Bolts, nuts, studs, and hand tools — normalized or quenched for reliable fastening in construction and industrial assembly.
Automotive & Transportation
Crankshafts, connecting rods, and suspension parts — normalized condition for balanced strength and machinability.
General Engineering
Chains, sprockets, and structural fittings — cost-effective for non-corrosive environments requiring medium strength.
5. Difference from Similar Grades (C45 vs C40 vs C50)
| Grade | Carbon Content | Key Advantage | Suitable Scenario |
|---|---|---|---|
| C45 | 0.42 – 0.50% | Balanced strength and toughness; good machinability | General mechanical parts (gears, shafts) with moderate wear demands |
| C40 | 0.37 – 0.44% | Higher ductility; easier to weld | Low-stress components (pipes, forgings) requiring formability |
| C50 | 0.47 – 0.55% | Superior hardness after heat treatment | High-wear applications (tools, dies) needing greater surface hardness |
6. Selection & Usage Precautions
- Heat Treatment Essential: Always apply quenching and tempering for high-strength applications to avoid brittleness; consult EN 10083 for specific cycles.
- Machinability Optimization: Use sulfur-free variants for precision machining; coolant recommended to prevent tool wear due to medium carbon content.
- Corrosion Limitations: Not suitable for harsh corrosive environments — apply protective coatings or select alloy steels if exposure to moisture or chemicals is expected.
- Quality Verification: Obtain material certificates confirming compliance with EN 10083-2; perform non-destructive testing (e.g., ultrasonic) for critical parts.
7. Get a Carbon Steel Quote
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