High-Strength Structural Hot-Rolled Steel Coil (HRC) – Q345B / S355JR Grade, Yield Strength ≥345MPa, for Bridges, Ships, Pressure Vessels & Heavy Machinery
Product Overview
Q345B (Chinese GB/T 1591 standard) and its European equivalent S355JR (EN 10025-2) are low-alloy high-strength structural steels widely recognized for their superior mechanical properties. With a minimum yield strength of 345 MPa and tensile strength ranging from 470 to 630 MPa, these grades offer significantly higher load-bearing capacity than conventional carbon steels like Q235 or S235JR. The addition of manganese (1.0%-1.6%) and controlled rolling processes enhance both strength and toughness without compromising weldability. Our hot-rolled coils in these grades are produced to international standards and are the preferred choice for critical infrastructure, heavy equipment manufacturing, and high-stress engineering applications.
Key Specifications
| Parameter | Range / Options |
|---|---|
| Thickness | 1.5 mm – 25.0 mm |
| Width | 1000 mm – 2000 mm |
| Coil Weight | 5 – 25 MT |
| Grades Available | Q345B (GB/T 1591), S355JR (EN 10025-2), A572 Gr 50 (ASTM) |
| Yield Strength (Min) | ≥345 MPa |
| Tensile Strength | 470 – 630 MPa |
| Elongation | ≥21% – 27% (depending on thickness) |
| Standards | GB/T 1591, EN 10025-2, ASTM A572 |
| Surface Condition | Black oxide (as-rolled); pickled & oiled (HRPO) available on request |
Core Advantages
High Strength-to-Weight Ratio – With a yield strength of ≥345 MPa, Q345B/S355JR allows for lighter, thinner structural sections while maintaining the same load capacity as lower-grade steels, reducing overall material consumption and project costs.
Excellent Weldability – Low carbon content (<0.2%) ensures reliable welding performance without pre-heating for most thicknesses, making it ideal for field fabrication.
Superior Toughness – Good low-temperature impact resistance ensures structural integrity in cold climates and demanding environments.
Outstanding Formability – Supports cold bending, stamping, and hot working processes, enabling complex structural shapes.
Corrosion Resistance – The alloy composition provides improved atmospheric corrosion resistance compared to plain carbon steels.
Applications
Bridge Construction: Main girders, trusses, and deck components
Shipbuilding: Hull structures, decks, and bulkheads
Pressure Vessels & Boilers: High-pressure storage tanks and steam equipment
Heavy Machinery: Crane booms, excavator arms, mining equipment frames
Building Structures: High-rise steel frameworks, stadium roofs, industrial plants
Transportation: Railway cars, truck chassis, trailer frames
Petroleum & Chemical: Storage tanks, pipeline supports, offshore platforms