Q345B Hot Rolled Steel Plate
Q345B hot rolled steel plate is a low-alloy, high-strength structural steel manufactured under Chinese standard GB/T 1591, serving as a functional equivalent to EN 10025-2 S355JR and ASTM A572 Grade 50. Delivering a minimum yield strength of 345 MPa alongside 34 J longitudinal impact energy at +20°C, this carbon steel grade provides optimal strength-to-weight performance, cold formability, and reliable field weldability across heavy structural fabrications, earthmoving machinery, and energy infrastructure.
Technical Specifications
|
Parameter / Standard |
Specification & Capability Details |
|
Thickness Range |
6 mm – 200 mm |
|
Width Range |
1,500 mm – 3,800 mm |
|
Length Range |
6,000 mm – 18,000 mm (Custom flame and plasma cutting available) |
|
Global Equivalents |
EN 10025-2 S355JR (1.0045) / ASTM A572 Grade 50 / JIS G3106 SM490A |
|
Chemical Limits (%) |
C ≤ 0.20, Si ≤ 0.50, Mn ≤ 1.70, P ≤ 0.035, S ≤ 0.035, Ceq ≤ 0.44 |
|
Dimensional Limits |
EN 10029 Class B/C, ASTM A6 (Flatness tolerance ≤ 3 mm/m) |
|
Surface Finish |
As-rolled, Shot blasted (ISO 8501-1 Sa 2.5), Shop primed (15–25 microns) |
|
Mill Certification |
EN 10204 3.1 / EN 10204 3.2 Inspection Certificate |
Mechanical Performance Matrix
|
Nominal Thickness (t) |
Min Yield Strength ReH |
Tensile Strength Rm |
Min Elongation A5 |
Min Impact Energy (+20°C) |
|
t ≤ 16 mm |
≥ 345 MPa |
470 – 630 MPa |
≥ 21% |
≥ 34 J (Charpy V-Notch) |
|
16 mm < t ≤ 40 mm |
≥ 335 MPa |
470 – 630 MPa |
≥ 21% |
≥ 34 J (Charpy V-Notch) |
|
40 mm < t ≤ 63 mm |
≥ 325 MPa |
470 – 630 MPa |
≥ 21% |
≥ 34 J (Charpy V-Notch) |
|
63 mm < t ≤ 100 mm |
≥ 315 MPa |
470 – 630 MPa |
≥ 20% |
≥ 34 J (Charpy V-Notch) |
|
100 mm < t ≤ 150 mm |
≥ 295 MPa |
450 – 600 MPa |
≥ 19% |
≥ 34 J (Charpy V-Notch) |
Manufacturing & Rolling Control
Slab Reheating: Continuous casting slabs are heated to 1,200°C – 1,250°C in a walking-beam furnace for microstructural homogenization.
High-Pressure Descaling: Primary mill scale is removed via 22 MPa hydro-descaling systems prior to breakdown pass rolling.
Controlled Rolling (TMCP): Thermo-mechanical control process refines ferrite-pearlite grain structures, achieving mechanical strength without heavy alloying.
Precision Hot Leveling: Multi-roll hot levelers correct plate crowning and wave defects immediately following accelerated cooling.
Key Application Engineering
Heavy Structural Frames: Building trusses, crane runways, power plant frameworks, and bridge girders.
Machinery & Earthmoving: Excavator booms, loader chassis, mining dump bodies, and crane telescoping arms.
Storage & Fluid Tanks: Vertical oil storage tanks, pressure vessel support rings, and industrial silos.
Marine & Offshore Support: Non-class ship hulls, deck structures, and port handling equipment.
Quality Assurance
Ultrasonic Inspection: 100% volumetric NDT per EN 10160 (Class S1/E1, S2/E2) or SEL 072 to verify freedom from internal laminations.
Heat-Specific Testing: Spectrographic chemical analysis, room-temperature tensile testing, and Charpy V-notch impact verification per heat lot.
Automated Dimension Checks: Continuous laser scanning verifies plate thickness, width, squareness, and diagonal tolerances.
Traceability Stamping: Hard-stamped heat numbers, plate sequence numbers, grade, and dimensions applied directly to every plate edge.
Value-Added Processing Options
CNC Cutting & Beveling: Oxy-fuel and CNC plasma profiling with cutting tolerances within +/-1.0 mm; double-V and K-bevel prep for direct site welding.
Z-Direction Testing: Through-thickness ductility testing compliant with ASTM A770 / EN 10164 (Z15, Z25, Z35 ratings) for heavy restrained welds.
Heat Treatment Conditions: Normalizing (N), Stress Relieving (PWHT), or Thermo-Mechanical Rolling (M) per project specification.
Surface Cleaning & Coating: Sa 2.5 automatic shot blasting and weldable iron-oxide shop priming.
Packaging, Logistics & Export Handling
Strapping & Protection: High-tensile steel strapping with corner guards; waterproof paper wrapping for long-haul sea transportation.
Stowing & Lashing: Wooden dunnage, timber chocks, and wire lashings inside containers or ship holds to prevent transit movement.
Shipment Routing: 20ft/40ft containers for lengths ≤ 11.8 m; breakbulk vessels for heavy-gauge or overlength plates up to 18 m.
Production Lead Times: 7 to 15 days for warehouse stock sizes; 20 to 30 days for factory rolling orders.
Technical FAQ
Q: Can Q345B steel plate be specified as a direct replacement for EN 10025-2 S355JR?
A: Yes. Both grades require a minimum yield strength of 345–355 MPa (depending on thickness) and identical +20°C longitudinal impact values. Chemical compositions are fully compatible, allowing Q345B to serve as an equivalent structural grade under EN 10204 3.1 certification.
Q: What is the weldability of Q345B steel plate during heavy fabrication?
A: Q345B maintains a low carbon equivalent (Ceq ≤ 0.44%). Plates under 25 mm thickness can be welded without preheating using standard SMAW, GMAW, or FCAW procedures under ambient workshop conditions.
Q: Is EN 10204 3.1 certification provided with every delivery?
A: Yes. Every shipment includes an original EN 10204 3.1 Mill Test Certificate detailing ladle chemical composition, mechanical test results, NDT inspection reports, and heat number traceability.
Hot Tags: q345b hot rolled steel plate, China q345b hot rolled steel plate manufacturers, suppliers, factory
Previous
No InformationYou Might Also Like
Send Inquiry