SAPH310: Low-Carbon Carbon Steel for Automotive Structures
SAPH310, specified under the JIS G3113 standard, is a low-carbon steel grade designed primarily for hot-rolled steel sheets and strips used in automotive structural components. With its controlled composition and enhanced formability, SAPH310 offers a balance of strength, ductility, and weldability, making it ideal for manufacturing vehicle frames, chassis parts, and body panels. This article explores its chemical composition, mechanical properties, production processes, applications, and comparative advantages.
1. Core Chemical Composition (JIS G3113 Standard)
| Element | Content Range | Function |
|---|---|---|
| Carbon (C) | ≤ 0.15% | Provides basic strength; low levels enhance ductility and weldability |
| Manganese (Mn) | 0.60 – 1.50% | Improves hardenability and tensile strength without compromising formability |
| Phosphorus (P) | ≤ 0.030% | Controlled to minimize brittleness and ensure cold formability |
| Sulfur (S) | ≤ 0.035% | Limited to reduce inclusions and prevent hot shortness during rolling |
| Silicon (Si) | ≤ 0.55% | Aids in deoxidation and enhances scalability resistance in processing |
2. Key Mechanical Properties (Room Temperature)
- Tensile Strength (TS): 310 – 410 MPa (JIS G3113 requirement; suitable for structural loads)
- Yield Strength (YS): ≥ 195 MPa (ensures adequate deformation resistance in forming)
- Elongation (A50): ≥ 32% (high ductility for deep drawing and bending operations)
- Bending Performance: Good formability with no cracking at 90° bend (radius depending on thickness)
- Hardness: Approximately 120-160 HB (soft enough for stamping and assembly)
3. Manufacturing Process Characteristics
- Steelmaking: Basic oxygen furnace (BOF) or electric arc furnace (EAF) followed by ladle refining to achieve low impurity levels and uniform composition.
- Hot Rolling: Slabs heated to 1200-1300°C, rolled to final thickness (2.0-14.0 mm) at finishing temperatures above 850°C, then coiled and normalized.
- Cooling and Coiling: Controlled air cooling to room temperature to retain fine-grained microstructure and avoid excessive hardening.
- Heat Treatment: Optional normalizing at 900-950°C for improved uniformity; no quenching required due to low carbon content.
- Surface Treatment: Pickling in hydrochloric or sulfuric acid to remove scale, followed by oiling for rust prevention during storage and transport.
4. Typical Application Fields
Automotive Structures
Chassis frames, wheel arches, floor panels, and reinforcement members — provides lightweight strength for improved fuel efficiency.
Body and Exterior Components
Door impacts, side sills, roof reinforcements, and underbody shields — excellent formability for complex shapes.
General Fabrication
Machinery guards, brackets, and structural supports in transportation equipment — cost-effective for high-volume production.
Wheel and Suspension Parts
Rim sections, suspension arms, and spring hangers — balances fatigue resistance with manufacturability.
5. Difference from Similar Grades (SAPH310 vs SPHC vs SPHD)
| Grade | Yield Strength (MPa) | Key Advantage | Suitable Scenario |
|---|---|---|---|
| SAPH310 | ≥ 195 | Enhanced strength with good formability | Automotive structural parts requiring moderate load-bearing |
| SPHC | ≥ 195 | Maximum ductility; lowest strength in series | Simple bending and drawing applications |
| SPHD | ≥ 215 | Higher yield for improved rigidity | Reinforced automotive components or thicker sections |
6. Selection & Usage Precautions
- Environmental Suitability: Best for mild corrosive environments; apply anti-rust coatings for outdoor or humid automotive use to prevent oxidation.
- Forming Limits: Avoid excessive strain rates during stamping; use lubricants to prevent cracking in high-deformation areas.
- Welding Guidelines: Compatible with MIG/TIG welding using ER70S electrodes; pre-heat not required, but control interpass temperature below 200°C.
- Quality Assurance: Verify compliance with JIS G3113 via mill certificates, including tensile tests and chemical analysis reports.
7. Get a Steel Quote
If you need customized SAPH310 steel products (sheets, coils, strips) or want to get a detailed price quote, please contact our team directly. Our specialists will provide professional technical support and competitive pricing based on your requirements.