GB/T 700 Q275A Carbon Structural Steel
GB/T 700 Q275A Carbon Structural Steel Properties, Equivalents and Applications
Comprehensive technical data for Q275A carbon structural steel according to GB/T 700, including chemical composition, mechanical and physical properties, international equivalents, and typical applications.
Cutting, welding, bolting, riveting, bending, forming, machining, galvanizing
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GB/T 700 Q275A Carbon Structural Steel Introduction
Q275A is a carbon structural steel grade specified in Chinese standard GB/T 700-2006. It belongs to the category of general-purpose carbon and low-alloy high-strength steel coil, characterized by a minimum yield strength of 275 MPa and a tensile strength range of 410–540 MPa.
- Grade Q275A is a killed steel (deoxidation method: Z) with a moderate carbon content (≤0.24%) and manganese up to 1.70%, providing good balance of strength and plasticity.
- The material is typically supplied in hot-rolled condition, as plates, strips, sections, or coils, and is widely used in welded, bolted, and riveted structures where higher strength than Q235 is required.
- Quality level A indicates no impact test requirement, making it suitable for static loading applications at ambient temperatures.
- It offers fair weldability, good machinability, and can be subjected to forming and bending processes.
GB/T 700 Q275A Carbon Structural Steel Chemical Composition
Chemical composition requirements for Q275A as per GB/T 700-2006. The steel is fully killed (deoxidation method Z). The limits apply to ladle analysis. Residual elements such as Cr, Ni, Cu are not intentionally added but limited to ensure product quality.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.24% | |
| Manganese (Mn) | ≤ 1.70% | Higher Mn improves strength and hardenability |
| Silicon (Si) | ≤ 0.35% | Deoxidizing element |
| Sulfur (S) | ≤ 0.050% | Quality level A |
| Phosphorus (P) | ≤ 0.045% | Quality level A |
| Chromium (Cr), max. | 0.30% | Residual element (not specified, but typical limit per GB/T 700) |
| Nickel (Ni), max. | 0.30% | Residual element |
| Copper (Cu), max. | 0.30% | Residual element |
| Nitrogen (N), max. | 0.008% | For steel produced by electric furnace; typically not specified |
GB/T 700 Q275A Carbon Structural Steel Thermal and Electrical Physical Properties
Physical properties for Q275A carbon steel at room temperature unless stated otherwise. These are typical values measured on annealed or normalized condition and are not specified in the delivery standard; they serve as engineering reference.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Room temperature |
| Modulus of Elasticity (E) | 200 – 210 | GPa | Room temperature, tension |
| Shear Modulus (G) | 79 | GPa | Calculated from E and ν |
| Poisson's Ratio (ν) | 0.30 | — | Room temperature |
| Thermal Expansion Coefficient (α) | 11.7 – 12.0 | ×10⁻⁶/K | 20°C to 100°C |
| Thermal Conductivity (λ) | 50 – 54 | W/(m·K) | At 20°C |
| Specific Heat Capacity (c) | 460 – 490 | J/(kg·K) | 20°C to 100°C |
| Electrical Resistivity (ρe) | 0.15 – 0.18 | μΩ·m | At 20°C |
GB/T 700 Q275A Carbon Structural Steel Mechanical Properties
Tensile and bending test results per GB/T 700-2006. Results depend on thickness (t). Impact test is not required for Q275A. All values are in longitudinal direction (unless noted).
| Property | Standard Requirement | Unit | Test Condition / Thickness |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 275 | MPa | Thickness ≤ 16 mm |
| Yield Strength (ReH) | ≥ 265 | MPa | 16 mm < t ≤ 40 mm |
| Yield Strength (ReH) | ≥ 255 | MPa | 40 mm < t ≤ 60 mm |
| Yield Strength (ReH) | ≥ 245 | MPa | 60 mm < t ≤ 100 mm |
| Yield Strength (ReH) | ≥ 225 | MPa | 100 mm < t ≤ 150 mm |
| Yield Strength (ReH) | ≥ 215 | MPa | 150 mm < t ≤ 200 mm |
| Tensile Strength (Rm) | 410 – 540 | MPa | Thickness ≤ 40 mm |
| Tensile Strength (Rm) | 400 – 540 | MPa | 40 mm < t ≤ 60 mm |
| Tensile Strength (Rm) | 390 – 530 | MPa | 60 mm < t ≤ 100 mm |
| Tensile Strength (Rm) | 380 – 520 | MPa | 100 mm < t ≤ 150 mm |
| Tensile Strength (Rm) | 370 – 510 | MPa | 150 mm < t ≤ 200 mm |
| Elongation after fracture (A) | ≥ 22 | % | t ≤ 40 mm, Lo = 5.65√So |
| Elongation after fracture (A) | ≥ 21 | % | 40 mm < t ≤ 60 mm |
| Elongation after fracture (A) | ≥ 20 | % | 60 mm < t ≤ 100 mm |
| Elongation after fracture (A) | ≥ 19 | % | 100 mm < t ≤ 150 mm |
| Elongation after fracture (A) | ≥ 18 | % | 150 mm < t ≤ 200 mm |
| Bend test (180°), d = bend diameter, a = specimen thickness | d = 2a | — | t ≤ 60 mm |
| Bend test (180°) | d = 3a | — | 60 mm < t ≤ 100 mm |
GB/T 700 Q275A Carbon Structural Steel Fully Equivalent Material Standards and Replacement Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 700-2006 | Q275A | Original grade |
| International | ISO 630-2:2011 (previously ISO 630:1995 Fe 430B) | S275JR | Similar strength and composition; JR requires impact energy 27 J at +20°C, while Q275A does not require impact test. Often used interchangeably in static applications. |
| European Union | EN 10025-2:2019 | S275JR | Closest matching EN grade; slightly higher elongation and impact requirement. Substitution is common; consult design code. |
| Germany (historical) | DIN 17100 | St44-2 | Obsolete standard; comparable static strength, but chemical and mechanical details differ. Historically used as equivalent. |
| Japan | JIS G3101 (2015) | SS400 | Minimum yield strength 245 MPa, slightly lower than 275 MPa, but widely accepted for general structures. Not fully equivalent but often substituted for Q275A in thickness ranges where strength is sufficient. |
| USA | ASTM A36/A36M | A36 | Yield strength 250 MPa (36 ksi) typical; lower minimum yield than Q275A. Used as practical alternative in many structural applications. |
GB/T 700 Q275A Carbon Structural Steel Application Introduction
Q275A steel coil and its derivatives are used in a wide range of structural and general engineering applications. Its moderate strength and fair weldability make it suitable for static and dynamically low-loaded structures. Typical industries and products are listed below.
Product Applications: Hot-rolled steel plates and coils, Welded H-beams, I-beams, channels, angles, Steel pipes and hollow sections, Prefabricated structural components, Corrugated sheets and decking, Anchor bolts and fasteners (non-high-strength)
Processed into products: Building columns and beams, Crane girders and runway beams, Bridge deck plates and stiffeners, Vehicle chassis and body framing, Machinery bases and frames, Tank wall and bottom plates, Transmission tower angles and plates, Support brackets and mounting plates
Application industries: Building and construction, Bridge engineering, Railway wagon and automobile frames, Shipbuilding (non-critical structural parts), Machinery and equipment manufacturing, Power transmission towers, Storage tanks and containers, Agricultural and earth-moving equipment
GB/T 700 Q275A Carbon Structural Steel Similar / Closest Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 700-2006 | Q275B / Q275C / Q275D | Higher quality levels with guaranteed impact toughness at +20°C, 0°C, and -20°C respectively. Chemical composition nearly identical but with lower S and P limits. Can be used where toughness is required. |
| China | GB/T 1591-2018 | Q345B | Low-alloy high-strength steel with yield strength ≥345 MPa. Higher strength and better weldability. Suitable for heavier loaded structures where weight saving is critical. Not a direct substitute, but often upgraded. |
| European Union | EN 10025-2 | S235JR | Lower strength grade (yield 235 MPa). Used when lower strength is acceptable; easier welding and forming. |
Notes:
Weldability: Q275A possesses fair weldability. Preheating may be required for thicker sections or restraint conditions. Low-hydrogen electrodes are recommended.
Formability: Suitable for cold bending and moderate forming. Minimum bend radius should be observed per the product standard.
Corrosion resistance: The steel has no inherent atmospheric corrosion resistance; hot-dip galvanizing or painting is recommended for exposed applications.
Quality level A: No impact test requirement. Not recommended for structures subject to dynamic loading at low temperatures. For such conditions, Q275B, C, or D should be considered.
Standard compliance: This data is based on GB/T 700-2006. For latest updates, consult the official standard and the material certificate from the supplier.
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