JIS G3131 Cold-Rolled Carbon Steel Sheets and Strips
JIS G3131 specifies cold-rolled carbon steel sheets and strips, widely used in manufacturing due to their excellent formability, surface quality, and cost-effectiveness. This standard covers grades such as SPCC, SPCD, and SPCE, which offer varying levels of strength and ductility for applications in automotive, appliances, and furniture. This article explores its chemical composition, mechanical properties, manufacturing processes, applications, and key considerations for selection.
1. Core Chemical Composition (JIS G3131 Standard)
| Grade | Element | Content Range | Function |
|---|---|---|---|
| SPCC (Commercial Quality) | Carbon (C) | ≤ 0.15% | Provides basic strength; controlled for formability |
| Manganese (Mn) | ≤ 0.60% | Improves deoxidation and strength | |
| Phosphorus (P) | ≤ 0.100% | Limited to maintain ductility | |
| Sulfur (S) | ≤ 0.050% | Controlled to prevent brittleness | |
| Others | Si, Cu, etc. | Trace elements for alloying balance | |
| SPCD (Drawing Quality) | Carbon (C) | ≤ 0.12% | Lower carbon for enhanced deep drawing |
| Manganese (Mn) | ≤ 0.50% | Supports formability | |
| Phosphorus (P) | ≤ 0.040% | Reduced for better workability | |
| Sulfur (S) | ≤ 0.040% | Minimized to avoid inclusions |
2. Key Mechanical Properties (Room Temperature)
- SPCC: Tensile Strength ≥ 270 MPa; Yield Strength ≥ 140-240 MPa; Elongation ≥ 36-38%
- SPCD: Tensile Strength ≥ 270 MPa; Yield Strength ≥ 140-240 MPa; Elongation ≥ 38-40% (superior drawing performance)
- SPCE: Tensile Strength ≥ 270 MPa; Yield Strength ≥ 190-240 MPa; Elongation ≥ 42% (deep drawing grade)
- Hardness: HR B ≤ 65 for all grades (annealed condition; suitable for stamping)
- Thickness Range: 0.15-3.5 mm for sheets; surface finishes include bright annealed or skin-passed
3. Manufacturing Process Characteristics
- Steelmaking: Basic oxygen furnace (BOF) or electric arc furnace (EAF) for low-carbon steel production, followed by continuous casting to slabs.
- Hot Rolling: Reheating slabs to 1100-1250°C, rolling to intermediate gauge (2-4 mm), and coiling for scale removal.
- Cold Rolling: Multi-pass reduction (up to 90%) at room temperature to achieve final thickness, with lubrication to prevent defects.
- Annealing: Batch or continuous annealing at 650-750°C to recrystallize structure, improve formability, and relieve stresses.
- Surface Treatment: Pickling in HCl or H2SO4 to remove oxides; skin pass rolling for flatness; optional coating for corrosion protection.
4. Typical Application Fields
Automotive Industry
Inner body panels, fenders, chassis components, and structural parts — leveraging excellent formability and weldability.
Household Appliances
Refrigerator shells, washing machine tubs, microwave interiors, and furniture frames — smooth surface for painting and assembly.
Electronics & Machinery
Computer casings, electrical enclosures, office equipment, and conveyor parts — cost-effective for high-volume production.
Construction & Fabrication
Metal shelves, ducting, roofing accessories, and light-gauge framing — balanced strength and ease of processing.
5. Difference from Similar Grades (JIS G3131 vs ASTM Equivalents)
| Grade (JIS) | ASTM Equivalent | Key Difference | Suitable Scenario |
|---|---|---|---|
| SPCC | A1008 CS Type A/B | Commercial quality; similar chemistry | General stamping and bending |
| SPCD | A1008 DDS | Improved drawing ratio | Moderate deep drawing operations |
| SPCE | A1008 EDDS | Highest ductility | Complex deep drawing (e.g., fuel tanks) |
6. Selection & Usage Precautions
- Formability Assessment: Select SPCD/SPCE for deep drawing to avoid cracking; perform Erichsen test for validation.
- Corrosion Considerations: Not inherently corrosion-resistant; apply zinc coating (galvanizing) or painting for outdoor use.
- Welding Compatibility: Suitable for resistance spot welding and MIG; use low-hydrogen fillers to prevent porosity.
- Quality Control: Inspect for surface defects (e.g., coil breaks, stretcher strains); require mill certificates compliant with JIS G3131.
7. Get a Carbon Steel Quote
If you need customized JIS G3131 cold-rolled carbon steel sheets or strips, or want a detailed price quote, please contact our team. We offer professional support and competitive pricing tailored to your specifications.