Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273-2005 for Automotive Frames
Explore S370L hot rolled steel coil properties, chemical composition, mechanical strength, applications, and equivalent grades per Chinese standard GB/T 3273-2005.
Hot rolling, controlled rolling, pickling, cutting, welding, forming, bending
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Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Introduction
S370L is a low-alloy high-strength hot-rolled steel grade specified in GB/T 3273-2005 for hot-rolled steel plates and strips used in automobile frames. It belongs to the series of automotive structural steels, designed with controlled microalloying (Nb, V, Ti) to achieve excellent formability, weldability, and high strength-to-weight ratio. Typical applications include heavy-duty truck frame rails, cross members, and reinforcement parts. The material is delivered in the hot-rolled or controlled-rolled condition, often with a pickled surface. Its chemical composition ensures low carbon equivalent for good welding performance, while maintaining minimum yield strength of 325-355 MPa depending on thickness.
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Chemical Composition
The following chemical composition limits are specified in GB/T 3273-2005 for grade S370L. Microalloying elements such as niobium, vanadium, or titanium may be added singly or in combination to refine grain size and improve mechanical properties.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤0.12 | |
| Silicon (Si) | ≤0.50 | |
| Manganese (Mn) | ≤1.00 | |
| Phosphorus (P) | ≤0.030 | |
| Sulfur (S) | ≤0.025 | |
| Aluminum (Al) | ≥0.015 | Minimum soluble aluminum content |
| Others (Nb, V, Ti) | May be added singly or in combination | Used for grain refinement and precipitation strengthening |
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Thermal and Electrical Physical Properties
The following physical properties are typical values for S370L steel (low-alloy structural steel) at room temperature unless otherwise specified. These values are not mandated by the standard but are representative for engineering calculations.
| Property | Standard Required Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Elastic modulus (E) | 210 | GPa | 20°C |
| Shear modulus (G) | ~81 | GPa | Calculated from E and ν |
| Poisson's ratio (ν) | 0.3 | – | Typical |
| Thermal expansion coefficient (α) | 12×10⁻⁶ | /K | 20–100°C |
| Thermal conductivity (λ) | ~50 | W/(m·K) | 20°C |
| Specific heat capacity | ~460 | J/(kg·K) | 20°C |
| Electrical resistivity (ρ_e) | ~0.13 | μΩ·m | 20°C |
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Mechanical Properties
Mechanical properties according to GB/T 3273-2005 for S370L hot-rolled steel. Yield and tensile properties depend on the nominal thickness t of the product. Bend test conditions specify a bending angle of 180° with sample width b ≥35 mm.
| Property | Standard Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥355 | MPa | Thickness ≤6 mm |
| Yield Strength (ReH) | ≥345 | MPa | Thickness >6~12 mm |
| Yield Strength (ReH) | ≥325 | MPa | Thickness >12~16 mm |
| Tensile Strength (Rm) | 370–480 | MPa | All thicknesses (≤16 mm) |
| Elongation (A) | ≥25 | % | Thickness ≤3 mm |
| Elongation (A) | ≥28 | % | Thickness >3~6 mm |
| Elongation (A) | ≥30 | % | Thickness >6~16 mm |
| Bend Test (180°, b≥35 mm) | d = a | – | Thickness ≤8 mm |
| Bend Test (180°, b≥35 mm) | d = 2a | – | Thickness >8~16 mm |
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Exact Equivalent Material Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | – | None | No fully equivalent international grade matches exactly the 370–480 MPa tensile range combined with the specific yield strength tiers of S370L. |
| Europe | EN 10149-2 | S355MC | Closest in yield strength (≥355 MPa) but has a higher tensile range (430–550 MPa); adjustment in forming may be needed. |
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Application Introduction
S370L is specifically designed for load-bearing structural components in the automotive sector. Its combination of high strength, good ductility, and excellent weldability makes it ideal for cold forming and welding operations typical in chassis manufacturing.
Product Applications: Truck frame longitudinal beams, Cross members and subframes, Reinforcement plates and brackets, Trailer chassis rails, Bus body structural members
Processed into products: Chassis main rails, Suspension mounting brackets, Engine support frames, Axle reinforcement parts, Frame side members and extensions
Application industries: Automotive manufacturing, Commercial vehicle production, Transportation equipment, Heavy machinery
Comprehensive Analysis of S370L Hot Rolled Steel Coil per GB/T 3273 Recommendations for Similar/Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10149-2 | S315MC | Lower strength, yield ≥315 MPa, tensile 390–510 MPa; suitable for less demanding parts. |
| Europe | EN 10149-2 | S355MC | Similar yield but higher tensile strength; often used as substitution with possible weight reduction. |
| Japan | JIS G3113 | SAPH370 | Lower yield strength (≥225 MPa) and tensile ≥370 MPa; not a strength-match but formable. |
| USA | ASTM A1011 | HSLAS Grade 50 Class 2 | Yield 340 MPa, tensile 410 MPa; similar application but note different thickness tolerances. |
Notes:
- Typical surface conditions: hot-rolled unpickled (black) or pickled and oiled.
- Dimensional tolerances and flatness conform to GB/T 3273-2005.
- No impact test is required in the standard; toughness can be agreed upon between supplier and buyer if needed.
- For enhanced atmospheric corrosion resistance, consult supplier for possible phosphorous addition.
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