Q345B Q345C Q345D Low Alloy High Strength Carbon Steel Plate Hot Rolled 3mm-300mm for Bridge and High-Rise Construction
Q345B/C/D Low Alloy High Strength Structural Steel Plate
Our Q345B/C/D low alloy high strength structural steel plate is the Chinese national standard equivalent to EN S355JR/J0/J2 and ASTM A572 Grade 50, designed for demanding structural applications where weight savings and high load-bearing capacity are critical. With yield strength ≥345 MPa — 38% higher than standard A36 — Q345 allows thinner, lighter structures without compromising safety. Available in three impact-tested grades (B: +20°C, C: 0°C, D: -20°C) from 3mm to 300mm, this product is specified in Middle Eastern mega-bridge projects, Southeast Asian high-rise developments, and African infrastructure programs.
Key Features
- 38% Stronger than A36: Yield strength ≥345 MPa enables material down-gauging, reducing structural weight and foundation costs while maintaining safety margins
- Three Impact Grades: Q345B (+20°C), Q345C (0°C), and Q345D (-20°C) with guaranteed Charpy impact energy ≥34J for applications in diverse climate zones
- Microalloyed Design: Small additions of Nb, V, Ti refine grain structure for improved strength, toughness, and weldability compared to plain carbon steel
- Excellent Weldability: Low carbon equivalent (CEV ≤0.45%) allows welding with standard procedures and minimal preheat requirements
- Global Equivalents: Direct substitution for S355JR/J0/J2 (EN 10025), A572 Gr50 (ASTM), SM490A (JIS), ensuring acceptance across international projects
Technical Specifications
| Grade | Q345B / Q345C / Q345D |
| Equivalent Standards | EN S355JR/J0/J2, ASTM A572 Gr50, JIS SM490A |
| Thickness | 3mm - 300mm |
| Width | 1500mm - 4500mm |
| Length | 6000mm - 18000mm (custom longer available) |
| Yield Strength | ≥345 MPa (thickness ≤16mm) |
| Tensile Strength | 470 - 630 MPa |
| Impact Energy | ≥34J (Q345B +20°C, Q345C 0°C, Q345D -20°C) |
Target Markets & Applications
- Middle East: Highway and railway bridge main girders, stadium roof trusses, mega-mall structural framing
- Southeast Asia: High-rise building core columns and beams, port crane structures, industrial plant steelwork
- Africa: Dam gate structures, mining plant heavy steelwork, long-span roof trusses for airport terminals
- Offshore platform topside modules, wind turbine tower flanges, heavy-lift crane booms
Packaging & Delivery
Shot blasted to SA2.5 cleanliness with shop primer coating available on request. Plates bundled by size with steel strapping on heavy-duty wooden or steel pallets. MTC EN 10204 3.1 and CE marking documentation provided. Custom cut-to-size by plasma/oxy-fuel. FOB Shanghai/Tianjin, CIF to Middle East, Southeast Asia, and Africa.
Get in Touch
Have questions about our products or want to discuss a custom order? Our team is ready to help you.