Q345B Hot Rolled Steel Coil
Q345B is a high-strength low-alloy structural steel coil under GB/T 1591, offering 345 MPa yield strength with excellent weldability and toughness. Ideal for high-rise building frames, heavy machinery, bridges, and transmission towers.
| Material | High Strength Low Alloy Steel (HSLA) |
|---|---|
| Grade / Standard | GB Q345B |
| Thickness | 1.5mm - 20.0mm |
| Width | 600mm - 2000mm |
| Inner Diameter (ID) | 508mm / 610mm / 760mm |
| Coil Weight | 5-30 Tons |
| Delivery Condition | Hot Rolled,Pickled & Oiled,TMCP (Thermo-Mechanical Control Process) / tmcp |
| Surface Treatment | coated |
| MOQ | 10 Tons |
| Delivery Time | 15-30 Days / In Stock |
| Loading Port | Tianjin / Shanghai / Qingdao |
Overview of Q345B Hot Rolled Steel Coil
Q345B is a high-strength low-alloy (HSLA) structural steel specified under the Chinese national standard GB/T 1591. The designation ‘Q’ represents the yield strength (Qu-fu-dian), ‘345’ indicates the minimum yield point of 345 MPa, and ‘B’ signifies the quality grade tested for impact toughness at 20°C. Compared to standard carbon steels, Q345B offers superior mechanical properties, including higher tensile strength and better atmospheric corrosion resistance, making it an essential material for high-performance structural engineering and heavy-duty manufacturing.
Shandong Tanglu Metal Material Co., Ltd. supplies premium Q345B hot rolled coils that undergo precise thermo-mechanical control processing (TMCP) to achieve a fine-grained microstructure. This grade is widely valued for its exceptional weldability and cold-forming capabilities, allowing for significant weight reduction in structural designs without compromising safety. For B2B clients, Q345B provides a robust and reliable HSLA solution that optimizes material efficiency and structural integrity in demanding industrial environments.
Key Features and Technical Advantages
The primary advantage of Q345B hot rolled steel coil is its enhanced yield strength, which is approximately 50% higher than standard Q235B steel. This high strength-to-weight ratio allows engineers to use thinner sections to achieve the same load-bearing capacity, leading to substantial savings in material costs and transport energy. Q345B is characterized by its excellent low-temperature toughness and superior fatigue resistance, ensuring reliable performance in dynamic and harsh weather conditions.
Our Q345B coils are available in a comprehensive range of thicknesses from 1.5mm to 20mm and widths up to 2000mm. The material features a controlled carbon equivalent (Ceq), ensuring that the steel remains highly weldable with minimal risk of hardening or cracking in the heat-affected zone. For high-precision applications, we provide Pickled and Oiled (P&O) Q345B coils, which offer a clean, mill-scale-free surface perfect for advanced automated fabrication, including high-speed laser cutting and specialized coating processes.
Main Applications of Q345B Hot Rolled Coil
Q345B hot rolled steel coil is the definitive material for high-stress structural applications. It is extensively used in the construction of large-span building frames, high-rise steel structures, and heavy-duty bridges. In the power and infrastructure sectors, it is a vital component for manufacturing high-voltage transmission towers, wind turbine masts, and specialized mining equipment frames where structural reliability is paramount.
Beyond civil engineering, Q345B is a critical material in the heavy machinery and transportation industries. It is used for fabricating crane booms, pressure vessel components (for moderate pressure), truck chassis, and shipbuilding structural members. Its versatility and high-strength performance also make it an ideal choice for manufacturing large-scale storage tanks, heavy-duty industrial racks, and various mechanical parts requiring high durability and wear resistance.
Why Choose Us for Q345B Hot Rolled Steel Coil
Shandong Tanglu Metal Material Co., Ltd. supplies high-grade Q345B hot rolled steel coil sourced from Tier-1 state-owned mills utilizing advanced rolling and cooling technologies. We provide comprehensive Mill Test Certificates (MTC) with every delivery, guaranteeing full compliance with GB/T 1591 standards, including precise chemical composition, yield/tensile strength data, and 20°C impact test results.
Our global logistics network ensures flexible coil weights and specialized seaworthy packaging to maintain material quality during long-distance transit. With a robust monthly supply capacity of 18,000 tons and professional technical support, we provide B2B clients with the material consistency and logistical reliability needed for high-stakes industrial and infrastructural projects worldwide.
📐 Dimension & Size Table
| Thickness (mm) | Width (mm) | Length (mm) | Weight (kg/m²) |
|---|---|---|---|
| 2.0 | 1000-1250 | 345 | 470-630 |
| 3.0 | 1000-1500 | 345 | 470-630 |
| 5.0 | 1000-1500 | 345 | 470-630 |
| 8.0 | 1250-1800 | 345 | 470-630 |
| 10.0 | 1250-2000 | 345 | 470-630 |
| 12.0 | 1250-2000 | 345 | 470-630 |
| 16.0 | 1500-2000 | 345 | 470-630 |
| 20.0 | 1500-2000 | 325 | 470-630 |
* Custom sizes available upon request. Tolerances per relevant international standards.
🔬 Chemical Composition
| Element | Min | Max | Display Value | Note |
|---|---|---|---|---|
| C | - | 0.20 | ≤0.20 | |
| Mn | 1.00 | 1.60 | 1.00-1.60 | |
| Si | - | 0.50 | ≤0.50 | |
| P | - | 0.035 | ≤0.035 | |
| S | - | 0.035 | ≤0.035 |
* Chemical composition may vary by heat, thickness and specification. Please refer to the actual mill test certificate.
⚙️ Mechanical Properties
| Property | Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (t≤16mm) | ≥345 | MPa | GB/T 1591 |
| Tensile Strength | 470 - 630 | MPa | |
| Elongation (t≤40mm) | ≥21 | % | |
| Impact Test (V-Notch) | ≥34 | J | At 20°C (Grade B) |
* Values shown are minimum requirements unless otherwise stated.
📦 Commercial Information
| Packaging | Standard seaworthy export packing, bundled with steel strips and angle iron protection, with desiccant inside to prevent moisture. |
|---|---|
| Payment Terms | T/T (Telegraphic Transfer),L/C (Letter of Credit),D/P (Documents against Payment),Western Union |
| Price Term | FOB,CFR,CIF,DDU |
| Supply Capacity | 18,000 Tons/Month |
| Loading Port | Tianjin / Shanghai / Qingdao |
Why Choose Our Q345B Hot Rolled Steel Coil?
High Strength Performance
345 MPa minimum yield strength allows for significant material reduction and increased structural efficiency in high-stress engineering designs.
Superior Low-Alloy Toughness
Enhanced with Manganese and Silicon to provide better impact resistance and fatigue life compared to standard carbon steels, ideal for dynamic loads.
Excellent Welding Characteristics
Controlled carbon equivalent ensures high-integrity structural joints with standard industrial welding methods, perfect for large-scale steel fabrication.
🏭 Applications of Q345B Hot Rolled Steel Coil
Q345B hot rolled steel coil is the definitive choice for high-strength structural engineering, essential for high-rise buildings, large-span industrial plants, and highway bridges. It serves as the primary material for fabricating heavy-duty crane booms, wind turbine towers, and mining machinery frames. In the transportation sector, it is widely utilized for truck chassis and shipbuilding. Q345B is also the preferred standard for manufacturing large-scale storage tanks, structural pipes, and specialized mechanical components requiring high durability.
📋 Quality & Certification
Our Certifications
- ✅ ISO 9001,CE,IATF 16949,SGS
- ✅ CE Marking
- ✅ SGS Certified
Mill Certificate Type
- 📋 EN 10204 3.1,Original Mill Test Certificate,Mechanical & Impact Test Report,Surface Quality Inspection Report,COA (Certificate of Analysis)
❓ Frequently Asked Questions
What is the difference between Q345B and Q235B?
Q345B is a low-alloy high-strength steel with a minimum yield strength of 345 MPa, whereas Q235B is a standard carbon steel with 235 MPa. Q345B allows for lighter designs and has better mechanical properties.
What is the equivalent of Q345B in the US standard?
Q345B is technically equivalent to ASTM A572 Grade 50. It also corresponds to the European S355JR and Japanese SM490 grades.
Can Q345B be used for low-temperature applications?
Q345B is tested for impact toughness at 20°C. For lower temperature environments, we recommend Q345D (tested at -20°C) or Q345E (tested at -40°C).
What is the carbon equivalent (Ceq) of Q345B?
The carbon equivalent of Q345B is typically controlled below 0.44%, ensuring excellent weldability without the need for extensive preheating for most thicknesses.
How do you ensure the quality of Q345B coils?
Every coil comes with an MTC (Mill Test Certificate) documenting its chemical heat analysis and mechanical testing (yield, tensile, elongation, and impact) conducted by certified laboratories.
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Q345B Hot Rolled Steel Coil
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