10# Carbon Steel: Low-Carbon Mild Steel for General Engineering & Cold Forming Applications
10# carbon steel (GB/T 699-2015 standard, equivalent to AISI 1010 or UNS G10100) is a low-carbon mild steel grade widely utilized in industrial manufacturing due to its excellent cold formability, weldability, and machinability. With a carbon content of ≤0.10%, this grade offers moderate strength (tensile strength 335-470 MPa) while maintaining superior ductility for deep drawing, bending, and cold heading operations. This article provides a technical breakdown of its chemical composition, mechanical properties, manufacturing processes, and application guidelines for engineering professionals.
1. Chemical Composition (GB/T 699-2015 Standard)
| Element | Content Range | Function |
|---|---|---|
| Carbon (C) | ≤ 0.10% | Low carbon content ensures high ductility and weldability while maintaining moderate strength |
| Manganese (Mn) | 0.35 – 0.65% | Improves hardenability and strength without compromising formability |
| Silicon (Si) | ≤ 0.35% | Acts as deoxidizer during steelmaking; enhances surface quality |
| Phosphorus (P) | ≤ 0.035% | Controlled impurity to prevent cold brittleness and improve toughness |
| Sulfur (S) | ≤ 0.035% | Minimized to reduce hot shortness and improve machinability |
| Chromium (Cr) | ≤ 0.15% | Residual element; no intentional alloying effect at this concentration |
| Nickel (Ni) | ≤ 0.25% | Residual element; may slightly improve toughness in trace amounts |
| Copper (Cu) | ≤ 0.25% | Residual element; excessive content may affect surface quality |
2. Mechanical Properties (Room Temperature)
- Tensile Strength (σb): 335-470 MPa (varies with heat treatment and section thickness)
- Yield Strength (σs): ≥ 185 MPa (minimum guaranteed for structural applications)
- Elongation (δ5): ≥ 33% (excellent ductility for cold forming operations)
- Reduction of Area (ψ): ≥ 55% (indicates high material toughness)
- Hardness (HB): ≤ 131 (Brinell hardness in annealed condition)
- Impact Energy (Ak): ≥ 108 J (Charpy V-notch at room temperature)
- Modulus of Elasticity: 200-210 GPa (typical for carbon steels)
3. Manufacturing Process Flow
- Steelmaking: Basic oxygen furnace (BOF) or electric arc furnace (EAF) with ladle refining to achieve precise chemical composition and low impurity levels. Vacuum degassing may be employed for critical applications to reduce hydrogen content.
- Continuous Casting: Produces blooms or billets with controlled solidification to prevent internal defects. Secondary cooling optimization ensures uniform microstructure.
- Hot Rolling: Heated to 1100-1250°C and rolled to final dimensions. Controlled rolling parameters prevent surface oxidation and ensure dimensional accuracy.
- Heat Treatment:
- Normalizing: 900-950°C followed by air cooling to refine grain structure
- Annealing: 870-920°C with furnace cooling to maximize ductility (typical for cold forming applications)
- Stress Relieving: 550-650°C for welded components to eliminate residual stresses
- Surface Treatment: Pickling in hydrochloric or sulfuric acid to remove scale, followed by oiling or phosphating for temporary corrosion protection during storage.
- Cold Finishing: For precision applications, cold drawing or turning to achieve tight dimensional tolerances (h9-h11) and superior surface finish (Ra 0.8-3.2 μm).
4. Key Application Fields
Automotive Components
Cold-headed fasteners (bolts, nuts, rivets), fuel tanks, exhaust system brackets, and chassis parts where formability and weldability are critical. Meets SAE J403 standards for chemical composition.
Machinery Manufacturing
Gears, shafts, and spindles for light-duty applications; machine frames and structural parts requiring good machinability. Often used in normalized or cold-drawn condition for improved surface finish.
Construction & Infrastructure
Reinforcement bars for non-structural concrete, metal framing systems, and architectural components. Galvanized 10# steel is commonly used for corrosion protection in outdoor applications.
Consumer Goods
Kitchen utensils, hardware tools (pliers, wrenches), and decorative metalwork. The grade’s excellent polishability makes it suitable for visible components requiring aesthetic appeal.
Pipe & Tube Production
Seamless and welded pipes for low-pressure fluid transportation (water, air, oil). Complies with ASTM A519 for mechanical tubing and ASTM A53 for general pipe applications.
Electrical Components
Magnetic cores, transformer laminations, and electrical enclosures where low carbon content minimizes magnetic aging and ensures consistent electrical properties.
5. Comparison with Similar Carbon Steel Grades
| Grade | Carbon Content | Key Properties | Typical Applications |
|---|---|---|---|
| 10# | ≤ 0.10% | Highest ductility, excellent cold formability, lowest strength in this comparison | Deep drawing, cold heading, welding structures |
| 15# | 0.12-0.17% | Balanced strength and formability, better machinability than 10# | General machinery parts, shafts, lightly stressed components |
| 20# | 0.17-0.23% | Higher strength with moderate ductility, good carburizing response | Gears, camshafts, components requiring surface hardening |
| 25# | 0.22-0.29% | Increased strength with reduced formability, better wear resistance | Axles, connecting rods, medium-stress mechanical parts |
| 35# | 0.32-0.39% | High strength with limited cold formability, good heat treatment response | Cranks, levers, high-stress components requiring toughness |
6. Technical Considerations & Processing Guidelines
- Cold Working: Excellent suitability for deep drawing (drawing ratio up to 2.1), bending (minimum bend radius 0.5x thickness), and cold heading. Intermediate annealing may be required for severe forming operations to restore ductility.
- Machining: Use high-speed steel (HSS) or carbide tools with cutting speeds of 60-90 m/min for turning and 30-50 m/min for drilling. Sulphurized or rephosphorized variants (e.g., 1215) offer improved machinability for high-volume production.
- Welding: Excellent weldability by all conventional methods (MIG, TIG, stick, submerged arc). Preheating generally not required for sections < 25mm. Use E6013 or ER70S-6 filler materials for optimal results.
- Heat Treatment:
- Carburizing at 900-950°C followed by quenching can achieve surface hardness of 55-60 HRC for wear-resistant applications
- Avoid rapid cooling from high temperatures to prevent distortion in complex shapes
- Corrosion Protection: Not inherently corrosion-resistant; requires protective coatings (zinc plating, painting, or phosphating) for outdoor or humid environments. Galvanized 10# steel (to ASTM A123) provides 50-100 years corrosion protection in atmospheric conditions.
- Quality Control: Verify mechanical properties via tensile testing (GB/T 228.1) and chemical composition through optical emission spectroscopy (OES). Ultrasonic testing (UT) recommended for critical applications to detect internal defects.
7. Material Certification & Standards Compliance
| Standard | Designation | Key Requirements |
|---|---|---|
| GB/T 699-2015 | 10# | Chinese standard specifying chemical composition and mechanical properties for quality carbon structural steels |
| ASTM A29/A29M | 1010 | American standard for general requirements of steel bars, carbon and alloy |
| JIS G4051 | S10C | Japanese standard for carbon steels for machine structural use |
| EN 10083-2 | C10E | European standard for quenched and tempered steels (non-alloy and alloy) |
| DIN 17200 | Ck10 | German standard for general-purpose carbon steels |
8. Request a Carbon Steel Quote
For customized 10# carbon steel products including hot-rolled plates, cold-drawn bars, seamless pipes, or precision-machined components, contact Baoli Iron & Steel’s technical team. We provide mill test certificates (EN 10204 3.1/3.2), third-party inspection reports, and tailored solutions for your specific application requirements.