C10 Carbon Steel: Non-Alloy Quality Steels (EN 10083 Series)
C10 carbon steel, designated as 1.1121 under the EN 10083 series for non-alloy quality steels, is a low-carbon, unalloyed steel grade optimized for quenching and tempering. With its controlled carbon content (0.07-0.14%), it offers excellent machinability, moderate strength, and good weldability, making it ideal for manufacturing mechanical components, fasteners, and structural parts. This article explores its chemical composition, mechanical properties, processing techniques, applications, and comparisons with related grades.
1. Core Chemical Composition (EN 10083-2 Standard)
| Element | Content Range | Function |
|---|---|---|
| Carbon (C) | 0.07 – 0.14% | Provides basic strength and hardenability; low level ensures good ductility and formability |
| Silicon (Si) | ≤ 0.40% | Acts as a deoxidizer; enhances elasticity and resistance to scaling at elevated temperatures |
| Manganese (Mn) | ≤ 0.40% | Improves hot workability and tensile strength; stabilizes the microstructure |
| Phosphorus (P) | ≤ 0.045% | Controlled impurity; higher levels can embrittle the steel and reduce weldability |
| Sulfur (S) | ≤ 0.045% | Improves machinability in free-cutting variants; strictly limited in standard grades to prevent brittleness |
| Chromium (Cr) | ≤ 0.40% | Trace residual; minor contribution to hardenability without alloying effects |
2. Key Mechanical Properties (Quenched and Tempered Condition)
- Tensile Strength (Rm): 450 – 600 MPa (depending on diameter and heat treatment)
- Yield Strength (Re): ≥ 280 MPa (adequate for moderate load-bearing applications)
- Elongation (A): ≥ 18% (good ductility for cold forming and bending operations)
- Hardness (HB): 121 – 163 (annealed state; increases to 200-250 HB after quenching and tempering)
- Impact Toughness (KV): ≥ 27 J at 20°C (maintains integrity under dynamic loading)
3. Manufacturing Process Characteristics
- Smelting: Basic oxygen furnace (BOF) or electric arc furnace (EAF) with ladle refining to achieve low impurity levels and uniform composition.
- Hot Rolling: Performed at 850-1100°C to produce bars, billets, or sections; controlled cooling to refine grain structure and avoid excessive scale formation.
- Cold Drawing: For precision bars, multi-pass drawing with intermediate annealing at 650-700°C to achieve dimensional accuracy and surface finish.
- Heat Treatment: Quenching in oil or water from 830-880°C, followed by tempering at 550-650°C to balance hardness and toughness while minimizing distortion.
- Surface Treatment: Pickling in hydrochloric acid to remove mill scale; optional shot blasting or phosphating for enhanced corrosion protection during storage.
4. Typical Application Fields
Automotive Components
Shafts, pins, gears, and fasteners in low-to-medium stress assemblies — valued for cost-effective machinability and consistent performance.
Machinery and Tools
Bolts, nuts, studs, and transmission parts for industrial equipment — suitable for environments requiring moderate strength and wear resistance.
Construction and Fabrication
Reinforcement bars, brackets, and structural fittings — easy to weld and form for on-site assembly in building projects.
Agricultural Equipment
Plough shares, harrow tines, and machinery frames — provides reliable durability in outdoor, variable-load conditions.
5. Difference from Similar Grades (C10 vs C15 vs C45)
| Grade | Carbon Content | Key Advantage | Suitable Scenario |
|---|---|---|---|
| EN C10 | 0.07-0.14% | Superior machinability and weldability; low cost | Light-duty components (pins, shafts) with minimal heat treatment needs |
| EN C15 | 0.12-0.18% | Better hardenability for case-hardening applications | Gears and wearing parts requiring surface hardness |
| EN C45 | 0.42-0.50% | Higher strength and wear resistance after quenching | Heavy-duty axles, crankshafts, and tools in demanding service |
6. Selection & Usage Precautions
- Corrosion Considerations: Prone to rust in moist or corrosive environments — apply protective coatings (e.g., zinc plating) or paints for extended outdoor use.
- Heat Treatment Control: Avoid overheating during quenching to prevent cracking; temper immediately after to reduce brittleness and internal stresses.
- Machining Practices: Use high-speed tools with coolant; sulfur-free variants for better weldability, but may require adjusted feeds for optimal chip control.
- Quality Verification: Obtain material certificates per EN 10204 to verify compliance with EN 10083-2 standards for composition and properties.
7. Get a Carbon Steel Quote
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