08F Carbon Steel: Low-Carbon Mild Steel for Cold Forming & Deep Drawing Applications
08F carbon steel (GB/T 699-2015 standard) is a high-purity, low-carbon mild steel grade specifically designed for cold forming, deep drawing, and stamping operations. With a maximum carbon content of 0.08%, this grade offers exceptional ductility, weldability, and surface finish quality while maintaining sufficient strength for structural applications. Its refined grain structure and controlled impurity levels make it ideal for automotive components, precision instruments, and complex-shaped metal parts where dimensional accuracy is critical.
1. Chemical Composition (GB/T 699-2015 Standard)
| Element | Content Range | Function |
|---|---|---|
| Carbon (C) | ≤ 0.08% | Ultra-low carbon content ensures maximum ductility and minimizes strain hardening during cold working |
| Manganese (Mn) | 0.25 – 0.50% | Enhances strength without compromising formability; acts as deoxidizer during smelting |
| Silicon (Si) | ≤ 0.03% | Controlled to minimum levels to prevent surface defects in deep drawing applications |
| Phosphorus (P) | ≤ 0.030% | Strictly limited to improve cold brittleness resistance and welding performance |
| Sulfur (S) | ≤ 0.020% | Ultra-low sulfur content prevents hot shortness and improves machinability |
| Copper (Cu) | ≤ 0.25% | Residual element; controlled to prevent surface defects during forming |
| Nickel (Ni) | ≤ 0.25% | Residual element; minimal content maintains consistent mechanical properties |
| Chromium (Cr) | ≤ 0.10% | Residual element; kept at trace levels to maintain pure iron characteristics |
2. Mechanical Properties (Cold Rolled Condition)
- Tensile Strength (σb): 270 – 410 MPa (varies with thickness and temper)
- Yield Strength (σ0.2): ≤ 235 MPa (ensures optimal formability)
- Elongation (δ): ≥ 32% (minimum for 1.0mm thickness; higher for thinner gauges)
- Hardness (HV): ≤ 130 (Vickers hardness in annealed condition)
- Bend Test: 180° cold bend on itself (no cracks for thickness ≤ 3mm)
- Cup Test (Erichsen): ≥ 11.0mm (excellent deep drawing capability)
3. Manufacturing Process & Quality Control
- Steelmaking: Electric arc furnace (EAF) + ladle refining furnace (LRF) with vacuum degassing to achieve ultra-low carbon and impurity levels. Continuous casting produces slabs with uniform grain structure.
- Hot Rolling: Controlled at 1100-1250°C with precise thickness reduction to develop favorable crystallographic texture for subsequent cold working.
- Cold Rolling: Multi-stand tandem mills with reduction rates up to 90% for thin gauges (0.1-3.0mm). Intermediate annealing at 680-720°C to restore ductility.
- Annealing: Continuous annealing lines with protective atmosphere (N₂-H₂) to prevent oxidation. Final grain size controlled at ASTM 7-9 for optimal formability.
- Surface Treatment: Skin-pass rolling (temper rolling) with 0.5-1.5% reduction to achieve specified surface roughness (Ra 0.8-1.6μm) and eliminate yield point elongation.
- Quality Inspection: 100% surface inspection using laser scanners; mechanical properties verified per GB/T 228.1; formability tested via cup test and bend test.
4. Key Application Fields
Automotive Components
Deep-drawn parts including fuel tanks, oil pans, brake components, and structural reinforcements. Meets automotive industry standards for dimensional tolerance and surface quality (VDA 239-100).
Precision Instruments
Watch cases, camera shutters, and measuring device components where tight tolerances and smooth surfaces are required. Excellent response to electroplating and PVD coatings.
Electrical Enclosures
EMC shielding cases, transformer cores, and electrical cabinet components. High magnetic permeability in annealed condition with low core loss characteristics.
Consumer Electronics
Smartphone frames, laptop casings, and appliance panels. Superior surface finish accepts various coatings including anodizing, powder coating, and laser etching.
Packaging Industry
Aerosol cans, food containers, and decorative tins. Excellent corrosion resistance when tin-plated or chrome-coated for food contact applications.
Architectural Hardware
Decorative trim, light fixtures, and furniture components. Easily formed into complex 3D shapes with minimal springback.
5. Comparison with Similar Low-Carbon Steel Grades
| Grade | Standard | Carbon Content | Key Characteristics | Typical Applications |
|---|---|---|---|---|
| 08F | GB/T 699-2015 | ≤ 0.08% | Ultra-low carbon; highest formability; excellent surface finish | Deep drawing, precision stamping, electroplated components |
| 08Al | GB/T 699-2015 | ≤ 0.10% | Aluminum-killed; improved aging resistance; better for welding | Structural parts requiring welding, moderate forming |
| DC01 | EN 10130 | ≤ 0.12% | European equivalent; slightly higher strength; good formability | General cold forming, automotive panels, household appliances |
| 1008 | ASTM A1008 | ≤ 0.10% | North American standard; similar properties with wider composition range | Exposed automotive parts, construction components |
| SPCC | JIS G3141 | ≤ 0.15% | Japanese standard; balanced properties; cost-effective | General-purpose forming, electrical components |
6. Processing Recommendations & Technical Considerations
- Cold Forming: Optimal for operations with deformation ratios up to 80%. Use tungsten carbide tooling for production runs >50,000 parts to maintain dimensional accuracy. Lubricate with chlorine-free drawing compounds.
- Welding: Suitable for all conventional welding methods (MIG, TIG, resistance). Preheat not required for thickness ≤ 3mm. Post-weld stress relief at 600-650°C recommended for critical components.
- Machining: Free-machining variant (08F Pb) available with lead additions for improved chip breaking. For standard 08F, use high-speed steel tools with positive rake angles and sharp edges.
- Heat Treatment: Full annealing at 850-950°C for 1-3 hours followed by furnace cooling to restore ductility after extensive cold working. Stress relief at 500-550°C for 1 hour to minimize distortion.
- Surface Treatment: Degrease with alkaline cleaners before plating. Phosphating recommended as pretreatment for paint systems. For electroplating, use cyanide-free zinc or nickel processes for environmental compliance.
- Storage Handling: Store in dry conditions with relative humidity <60%. Use rust-preventive paper for long-term storage. Avoid contact with copper or brass to prevent galvanic corrosion.
7. Request a Carbon Steel Quote
Require high-quality 08F carbon steel in coils, sheets, or custom-blanked parts? Our mill produces 08F with thickness ranging from 0.1mm to 4.0mm in various surface finishes (matte, bright, or pre-coated). Contact our technical sales team for material certificates, forming simulations, or competitive pricing tailored to your production requirements.