Q235 steel is a widely used Chinese standard mild carbon structural steel. It is known for its excellent weldability, formability, and cost-effectiveness.
With a yield strength of 235 MPa, it is suitable for general structural applications including buildings, bridges, machinery, vehicles, and storage containers.
Features and Advantages
Low Carbon Content – ≤0.22%, ensures good ductility, weldability, and formability.
High Tensile Strength – 370–500 MPa, allowing it to withstand heavy loads.
Good Ductility and Toughness – Can absorb energy under impact or dynamic loads without fracturing.
Excellent Weldability – Supports arc, resistance, and gas welding.
Wide Applications – Structural components, machinery, automotive parts, bridges, transmission towers, scaffolding, and more.
Corrosion Protection – Can be galvanized or coated for improved corrosion resistance.
Medium Hardness – Brinell hardness of 100–130 HB, allowing easy machining, drilling, and processing.
International Standards Compliance – GB/T 700, ASTM, JIS, DIN, EN standards.
Customizable Sizes – Width: 1510–2300 mm, Thickness: 1.5–100 mm, Length: 6–12 m; processing services include cutting, bending, punching, welding, decoiling.
Q235 Steel Grades
Q235 is divided into four metallurgical grades according to GB/T 700:
| Grade | C (%) ≤ | Si (%) ≤ | Mn (%) ≤ | P (%) ≤ | S (%) ≤ | Key Characteristics |
|---|---|---|---|---|---|---|
| Q235A | 0.22 | 0.35 | 1.40 | 0.045 | 0.050 | Basic version, good weldability & formability |
| Q235B | 0.20 | 0.35 | 1.40 | 0.045 | 0.045 | Improved toughness, better mechanical properties |
| Q235C | 0.17 | 0.35 | 1.40 | 0.040 | 0.040 | Enhanced low-temperature performance, improved impact resistance |
| Q235D | 0.17 | 0.35 | 1.40 | 0.035 | 0.035 | Highest quality, best low-temperature toughness |
Note: Lower carbon, phosphorus, and sulfur improve flexibility, toughness, and weldability.
Mechanical and Physical Properties
| Property | Value |
|---|---|
| Yield Strength | 235 MPa (d ≤16 mm), decreases with larger diameter |
| Tensile Strength | 370–500 MPa |
| Elongation at Break | ~26% |
| Brinell Hardness | 100–130 HB |
| Density | 7.85 g/cm³ |
| Melting Point | ~1493 °C |
| Elastic Modulus | 200 GPa |
| Thermal Conductivity | 49–53 W/m·K (0–100 °C) |
| Coefficient of Thermal Expansion | 11.3–11.6×10⁻⁶/K |
| Poisson's Ratio | 0.24–0.28 |
| Electrical Resistivity | ~0.15 μΩ·m (20 °C) |
Chemical Composition (GB/T 700 Standard)
| Element | Q235A | Q235B | Q235C | Q235D | Function |
|---|---|---|---|---|---|
| C | 0.22 | 0.20 | 0.17 | 0.17 | Strength control |
| Si | 0.35 | 0.35 | 0.35 | 0.35 | Deoxidizer, minor strength |
| Mn | 1.40 | 1.40 | 1.40 | 1.40 | Strength and hardenability |
| P | 0.045 | 0.045 | 0.040 | 0.035 | Impurity, toughness impact |
| S | 0.050 | 0.045 | 0.040 | 0.035 | Impurity, machinability impact |
Product Forms and Processing
Forms: Wire, coil, sheet, rod, flat bar, plain round bar, channel steel, tube, rebar, I-beam, C-channel
Processing Services: Welding, punching, cutting, bending, decoiling
Techniques: Hot-rolled, cold-rolled, cold-drawn
Surface: Non-oiled, anti-rust oil, hot-dip galvanizing, cold-dip galvanizing
Customizable Dimensions: Thickness, width, length, diameter
Typical Applications
Structural beams, columns, and frameworks for buildings and bridges
Metal furniture frames
Gearbox and engine parts
Agricultural machinery and railway tracks
Roof structures, purlins, and scaffolding
Mechanical parts: rods, screws, nuts, brackets
Vehicles, containers, boilers, and transmission towers
Global Equivalents
| Country | Standard | Equivalent Steel |
|---|---|---|
| USA | ASTM | A36 |
| Europe | EN | S235JR / S235J0 / S235J2 |
| Japan | JIS | SS400 |
| India | IS 2062 | E250 |
| Germany | DIN | St37-2 / SM400A |
| UK | BS | E235B |
| ISO | ISO | 630-2 |
Q235 steel is economical, widely available, and versatile, making it ideal for general structural applications. Its low carbon content, good ductility, and weldability enable efficient fabrication, while its mechanical properties support heavy loads and general structural use.
For specialized applications or higher-strength requirements, consider Q345, Q255, or other higher-grade steels.
