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Technical Specifications
Product Overview
Metallurgical Characteristics
GB Q345 is a low-alloy high-strength structural steel featuring a fine-grained ferrite-pearlite microstructure achieved through controlled rolling and accelerated cooling processes. The steel's enhanced properties result from solid solution strengthening, precipitation hardening, and grain refinement mechanisms. MetalZenith's advanced thermomechanical controlled processing (TMCP) ensures optimal balance between strength, toughness, and weldability.
Heat Treatment Processes
MetalZenith employs sophisticated heat treatment protocols for GB Q345 steel:
- Normalizing: 900-950°C followed by air cooling for stress relief and grain refinement
- Quenching & Tempering: Austenitizing at 880-920°C, water quenching, tempering at 600-650°C
- Stress Relief: 580-620°C for 1-2 hours to eliminate residual stresses
- Controlled Rolling: Finish rolling temperature 750-850°C for optimal microstructure
Manufacturing Process Excellence
MetalZenith's production process begins with carefully selected raw materials processed in state-of-the-art electric arc furnaces with secondary refining capabilities. The steel undergoes vacuum degassing, ladle metallurgy treatment, and continuous casting to ensure chemical homogeneity and cleanliness. Our controlled rolling mills with computerized process control deliver precise dimensional accuracy and superior surface quality.
Quality Standards & Certifications
All GB Q345 steel products manufactured by MetalZenith comply with GB/T 1591-2018 standards and undergo comprehensive testing including:
- Chemical composition analysis using optical emission spectrometry
- Mechanical property testing per ASTM and EN standards
- Non-destructive testing including ultrasonic and magnetic particle inspection
- Charpy V-notch impact testing at specified temperatures
- Dimensional inspection and surface quality verification
- Third-party certification available from Lloyd's, DNV, ABS, and other recognized bodies
Welding & Fabrication Guidelines
GB Q345 steel exhibits excellent weldability with proper procedures. Recommended welding parameters include preheating to 100-150°C for thick sections, interpass temperature control below 250°C, and post-weld heat treatment when required. Compatible welding consumables include E7018, ER70S-6, and equivalent low-hydrogen electrodes. MetalZenith provides comprehensive welding procedure specifications and technical support for critical applications.
🧪 Chemical Composition
| Element | Composition (%) | Grade A | Grade B |
|---|---|---|---|
| Carbon (C) | ≤ 0.20 | ≤ 0.18 | ≤ 0.20 |
| Manganese (Mn) | 1.00-1.60 | 1.20-1.60 | 1.00-1.60 |
| Silicon (Si) | ≤ 0.55 | ≤ 0.55 | ≤ 0.55 |
| Phosphorus (P) | ≤ 0.035 | ≤ 0.030 | ≤ 0.035 |
| Sulfur (S) | ≤ 0.035 | ≤ 0.030 | ≤ 0.035 |
| Chromium (Cr) | ≤ 0.30 | ≤ 0.30 | ≤ 0.30 |
| Nickel (Ni) | ≤ 0.50 | ≤ 0.50 | ≤ 0.50 |
| Copper (Cu) | ≤ 0.55 | ≤ 0.55 | ≤ 0.55 |
| Vanadium (V) | ≤ 0.15 | ≤ 0.15 | ≤ 0.15 |
| Niobium (Nb) | ≤ 0.07 | ≤ 0.07 | ≤ 0.07 |
| Titanium (Ti) | ≤ 0.20 | ≤ 0.20 | ≤ 0.20 |
| Aluminum (Al) | ≥ 0.015 | ≥ 0.015 | ≥ 0.015 |
⚙️ Mechanical Properties
| Property | Q345A | Q345B | Q345C | Q345D |
|---|---|---|---|---|
| Yield Strength (MPa) | ≥ 345 | ≥ 345 | ≥ 345 | ≥ 345 |
| Tensile Strength (MPa) | 470-630 | 470-630 | 470-630 | 470-630 |
| Elongation (%) | ≥ 21 | ≥ 21 | ≥ 22 | ≥ 22 |
| Impact Energy at 20°C (J) | - | ≥ 34 | ≥ 34 | ≥ 34 |
| Impact Energy at 0°C (J) | - | - | ≥ 34 | ≥ 34 |
| Impact Energy at -20°C (J) | - | - | - | ≥ 34 |
| Brinell Hardness (HB) | ≤ 229 | ≤ 229 | ≤ 229 | ≤ 229 |
| Young's Modulus (GPa) | 206 | 206 | 206 | 206 |
| Shear Modulus (GPa) | 80 | 80 | 80 | 80 |
| Poisson's Ratio | 0.26 | 0.26 | 0.26 | 0.26 |
| Fatigue Limit (MPa) | 160-180 | 160-180 | 160-180 | 160-180 |
🔬 Physical Properties
| Property | Value | Temperature Range |
|---|---|---|
| Density | 7.85 g/cm³ | 20°C |
| Melting Point | 1510-1540°C | - |
| Thermal Conductivity | 54 W/m·K | 20°C |
| Thermal Expansion Coefficient | 12.5×10-6/K | 20-100°C |
| Specific Heat Capacity | 460 J/kg·K | 20°C |
| Electrical Resistivity | 0.16 µΩ·m | 20°C |
| Magnetic Permeability | Ferromagnetic | 20°C |
| Thermal Diffusivity | 15.0 mm²/s | 20°C |
| Curie Temperature | 770°C | - |
| Coefficient of Linear Expansion | 13.1×10-6/K | 100-300°C |
| Thermal Conductivity (High Temp) | 42 W/m·K | 300°C |
| Emissivity | 0.85-0.95 | High Temperature |
📏 Product Specifications
| Specification | Available Options | Standards |
|---|---|---|
| Product Forms | Plates, Sheets, Bars, Beams, Channels, Angles, Tubes, Pipes | GB/T 1591, GB/T 700 |
| Plate Thickness | 6-300 mm | GB/T 3274 |
| Sheet Thickness | 0.5-6 mm | GB/T 912 |
| Bar Diameter | 10-300 mm | GB/T 702 |
| Pipe Outer Diameter | 21.3-1420 mm | GB/T 8162, GB/T 8163 |
| Surface Finish | Hot Rolled, Cold Rolled, Pickled, Shot Blasted | GB/T 709 |
| Heat Treatment | As-Rolled, Normalized, Quenched & Tempered | GB/T 1591 |
| Dimensional Tolerance | ±0.1-±3.0 mm (depending on form) | GB/T 709, GB/T 702 |
| Length Range | 3-18 meters (standard), Custom lengths available | Customer Specification |
| Width Range | 1000-4000 mm (plates/sheets) | GB/T 709 |
| Quality Grades | Q345A, Q345B, Q345C, Q345D, Q345E | GB/T 1591-2018 |
| Equivalent Standards | ASTM A572 Gr50, EN S355, JIS SM490 | International |
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Our Advantages in Processing GB Q345
Advanced Controlled Rolling Technology
MetalZenith employs sophisticated controlled rolling and accelerated cooling processes to achieve optimal grain refinement and enhanced mechanical properties in GB Q345 steel, ensuring superior strength-to-weight ratios and improved toughness characteristics.
Comprehensive Quality Control Systems
Our integrated quality management system features real-time chemical composition monitoring, automated mechanical testing, and advanced non-destructive evaluation techniques, guaranteeing consistent product quality and full traceability for every batch of GB Q345 steel.
Flexible Customization & Global Supply
MetalZenith offers extensive customization options for GB Q345 steel including specialized heat treatments, precision cutting, and custom dimensions. Our global distribution network ensures reliable delivery worldwide with comprehensive technical support and engineering consultation services.
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