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Q345B is a premium low-alloy high-strength structural steel produced according to the Chinese GB/T 1591 standard. Engineered for superior mechanical performance, this carbon alloy steel (C < 0.2%) strikes an optimal balance between strength, weldability, and toughness, making it a cornerstone material for heavy-duty industrial applications.
With a designated yield point of approximately 345MPa, Q345B is extensively utilized in the construction of bridges, marine vessels, high-rise buildings, and pressure vessels. Its versatility allows engineers to reduce the overall weight of structural components—such as car girders and chassis parts—without compromising the safety or integrity of the project.
| Material Grade | Q345B / Q355B (GB/T 1591) | Material Density | 7.85 g/cm³ |
|---|---|---|---|
| Yield Strength | 345 MPa | Tensile Strength | 470-630 MPa |
| Available Thickness | 0.1mm – 300mm | Available Width | 0.6m – 3m |
| Available Length | 4m – 12m (Customizable) | Production Technique | Hot Rolled |
| Applicable Standards | GB, ASTM, AISI, DIN, JIS, EN | Quality Grades | Q345A, B, C, D, E |
Engineered with a 345MPa yield point to ensure structural stability under extreme loads.
High strength-to-weight ratio allows for reduced material usage in chassis and girders.
Low carbon content (C < 0.2%) ensures excellent welding performance for complex structures.
Ideal for bridges, ships, pressure vessels, and automotive structural components.
Available in a wide range of thicknesses from 0.1mm up to 300mm for precise needs.
Fully compliant with GB/T 1591-2008 and 2018 standards for global quality assurance.
Annual production capacity of 10 million tons ensures stable supply for large projects.
Equipped with two 3500mm medium-thick plate lines for heavy-duty requirements.
Dedicated quenching and tempering lines to optimize steel hardness and toughness.
Utilizing 1250mm hot-rolled coil and high-speed wire rod lines for efficiency.
Recognized as a key plate production base in Hebei Province, China.
Ability to provide tailored lengths, widths, and thicknesses to client specifications.
| Performance Metric | Ordinary Carbon Steel | Q345B Low Alloy Steel | Industrial Impact |
|---|---|---|---|
| Yield Strength | Low / Standard | High (345MPa) | Increased Load Capacity |
| Material Weight | Heavy | Optimized / Lighter | Reduced Logistics Costs |
| Structural Life | Standard | Extended | Lower Maintenance Cost |
| Welding Efficiency | Variable | Superior | Faster Construction Time |
| Overall ROI | Baseline | High Efficiency | Optimal Long-term Value |
The "Q" represents the Chinese Pinyin word "qu fu dian," which translates to "Yield Point," indicating that the steel’s classification is based on its minimum yield strength.
Generally, the yield value of Q345B decreases as the thickness of the material increases. Precise data for different thicknesses should be verified via the technical datasheet.
It is widely used in the construction of bridges, vehicle chassis, marine shipbuilding, high-rise building frameworks, and pressure vessels.
Q355 is the updated standard (GB/T 1591-2018) replacing Q345 (GB/T 1591-2008). While very similar, Q355 reflects updated testing and classification requirements in modern engineering.
Yes, it is an excellent choice for automotive parts like transmission shafts and car girders, as it helps reduce the overall weight of the vehicle while maintaining strength.
According to the GB/T 1591 standard, Q345 material is available in five quality grades: Q345A, Q345B, Q345C, Q345D, and Q345E.
