Q370qE Bridge Steel Plate
High-strength structural steel specifically designed for heavy-load bridge construction in extreme cold regions, meeting GB/T 714-2015 standards for durability and reliability in low temperature conditions down to -40°C.
About Q370qE Steel
Q370qE is a Chinese standard (GB/T 714-2015) high-strength low alloy structural steel specifically developed for heavy-load bridge construction in extreme cold climate zones.
The "q" in the designation stands for bridge (qiaoliang in Chinese), while "E" indicates the steel's impact test temperature of -40°C, making it suitable for extreme cold climate conditions in northern China, northeast China and high-altitude regions.
It offers exceptional strength, excellent weldability, and superior low-temperature toughness, making it the premium choice for long-span and heavy-load bridge infrastructure in severe cold environments.
Technical Specifications
Basic Information
Mechanical Properties
| Thickness (mm) | Yield Strength (MPa) ≥ | Tensile Strength (MPa) | Elongation (%) ≥ | Impact Energy (J) ≥ |
|---|---|---|---|---|
| ≤16 | 370 | 490-650 | 20 | 34 |
| >16-35 | 350 | 490-650 | 20 | 34 |
| >35-50 | 340 | 490-650 | 20 | 34 |
| >50-100 | 320 | 470-630 | 20 | 34 |
Chemical Composition (wt%)
| Element | C ≤ | Si ≤ | Mn | P ≤ | S ≤ | Nb ≤ | V ≤ | Ti ≤ | Ni ≤ | Cu ≤ |
|---|---|---|---|---|---|---|---|---|---|---|
| Content | 0.16 | 0.55 | 1.20-1.80 | 0.020 | 0.015 | 0.08 | 0.15 | 0.02 | 0.50 | 0.30 |
Note: Carbon equivalent (Ceq) ≤ 0.45%, Weldability carbon equivalent (Pcm) ≤ 0.24%. Higher nickel content (up to 0.50%) significantly improves ultra-low-temperature toughness for extreme cold applications down to -40°C.
International Standards Comparison
Mechanical Properties Comparison (≤16mm thickness)
| Property | Q370qE (GB/T 714-2015) | S355NL (EN 10025) | A709 Gr50S (ASTM A709) |
|---|---|---|---|
| Yield Strength (MPa) min | 370 | 355 | 345 (50 ksi) |
| Tensile Strength (MPa) | 490-650 | 470-630 | 485-655 (70-95 ksi) |
| Elongation (%) min | 20 | 21 | 21 |
| Impact Test Temperature (°C) | -40 | -50 | -18 (0°F) |
| Impact Energy (J) min | 34 | 27 | 27 (20 ft-lb) |
| Carbon Equivalent (Ceq) max | 0.45% | 0.45% | 0.45% |
Chemical Composition Comparison (wt%)
| Element | Q370qE (max/ range) | S355NL (EN 10025) (max/ range) | A709 Gr50S (ASTM A709) (max/ range) |
|---|---|---|---|
| Carbon (C) | ≤0.16% | ≤0.20% | ≤0.23% |
| Silicon (Si) | ≤0.55% | ≤0.55% | 0.15-0.40% |
| Manganese (Mn) | 1.20-1.80% | 1.00-1.60% | 1.00-1.50% |
| Phosphorus (P) | ≤0.020% | ≤0.025% | ≤0.035% |
| Sulfur (S) | ≤0.015% | ≤0.020% | ≤0.040% |
| Niobium (Nb) | ≤0.08% | ≤0.06% | ≤0.05% |
| Vanadium (V) | ≤0.15% | ≤0.15% | ≤0.06% |
| Titanium (Ti) | ≤0.02% | ≤0.05% | ≤0.03% |
Key Differences Summary:
- Q370qE offers higher yield strength (370MPa) compared to international equivalents, ideal for heavy-load bridge applications in extreme cold environments
- Lower carbon content (≤0.16%) and stricter P/S control (0.020/0.015%) ensure superior ultra-low temperature toughness at -40°C
- Higher nickel allowance (0.50%) significantly enhances low-temperature performance for severe cold regions
- Impact test temperature of -40°C makes it suitable for extreme cold regions in northern/northeastern China and high-altitude areas
- Lower carbon equivalent (0.45%) improves weldability for construction in cold environments
- Optimized manganese content (1.20-1.80%) enhances strength while maintaining excellent low-temperature toughness
Application Cases
Heilongjiang Highway Bridge
Used in the main girders of a 2.2km long heavy-load highway bridge in Heilongjiang province, supporting high traffic loads in extreme winter conditions down to -35°C.
- Plate thickness: 35mm-70mm
- Total usage: 18,500 metric tons
- Service life: Designed for 100 years in extreme cold
Tibet High-Altitude Railway Bridge
Applied in a high-altitude railway bridge project in Tibet, providing exceptional fatigue resistance and ultra-low temperature performance at -40°C.
- Plate thickness: 25mm-60mm
- Total usage: 21,200 metric tons
- Operates at altitudes over 4000m, -40°C
Inner Mongolia Border Port Bridge
Utilized in a heavy-duty border port bridge in Inner Mongolia, designed to withstand heavy truck loads and extreme cold climate conditions down to -38°C.
- Plate thickness: 30mm-80mm
- Total usage: 14,800 metric tons
- Special anti-corrosion coating for cold, dry environment
Other Typical Applications
Frequently Asked Questions (FAQ)
What is the difference between Q370qE and Q370qD steel?
The main differences between Q370qE and Q370qD bridge steel plates are:
- Impact test temperature: Q370qE (-40°C) vs Q370qD (-20°C)
- Carbon content: Q370qE (≤0.16%) vs Q370qD (≤0.18%)
- Phosphorus/Sulfur limits: Q370qE (0.020/0.015%) vs Q370qD (0.025/0.020%)
- Nickel allowance: Q370qE (0.50%) vs Q370qD (0.30%)
- Carbon equivalent: Q370qE (0.45%) vs Q370qD (0.48%)
- Applications: Q370qE for extreme cold regions (-40°C), Q370qD for moderate cold (-20°C)
What welding precautions are needed for Q370qE in extreme cold weather?
Q370qE has excellent weldability (Ceq ≤ 0.45%), but special precautions apply for welding in extreme cold weather:
- Preheat base metal to ≥15°C when ambient temperature < -10°C (higher than Q370qD)
- Preheat to 100-150°C for plates >40mm thick or when temperature < -20°C
- Use ultra-low hydrogen welding electrodes (E5015-G/E5016-G) to prevent cold cracking
- Maintain interpass temperature ≥100°C during multi-pass welding in extreme cold
- Post-weld heat treatment mandatory for thickness >50mm or critical components in -40°C environments
- Welding should be performed in sheltered areas when ambient temperature < -15°C
Follow WPS specifically qualified for ultra-low temperature high-strength steels.
What is the service temperature range for Q370qE steel?
Q370qE is engineered for extreme cold environments with the following temperature range:
- Minimum operating temperature: -40°C (meets impact energy requirements at this temperature)
- Recommended continuous service: -40°C to 200°C
- Maximum short-term service temperature: 300°C
- Optimal welding temperature: ≥15°C (preheating required below this)
- Storage/transport temperature: No lower limit with proper handling
Q370qE is the ultra-low temperature grade in the Q370q series, suitable for extreme cold climate heavy-load applications in northern/northeastern China and high-altitude regions.
What special treatments enhance Q370qE performance in extreme cold regions?
Several specialized treatments optimize Q370qE for extreme cold environment heavy-load applications:
- TMCP (Thermo-Mechanical Control Process) with accelerated cooling for refined grain structure
- Ultra-strict impurity control (P≤0.020%, S≤0.015%) to prevent brittle fracture at -40°C
- Normalized heat treatment with precise temperature control for uniform microstructure
- Niobium microalloying (up to 0.08%) + nickel addition (up to 0.50%) for ultra-low temperature toughness
- Stress relief annealing after welding for heavy-load components in extreme cold
- Special anti-corrosion coatings with low-temperature flexibility for -40°C environments
- Shot peening for critical components to improve fatigue resistance in cold conditions
These treatments ensure reliable heavy-load performance in extreme cold climate conditions down to -40°C.
What quality certifications are provided for Q370qE steel plates?
We provide comprehensive certification for Q370qE steel plates, including:
- Mill Test Certificate (MTC) EN 10204 3.1 / 3.2 with -40°C impact test results
- GB/T 714-2015 standard compliance certificate for ultra-low temperature grades
- Low-temperature toughness test reports (-40°C Charpy V-notch)
- Third-party inspection (SGS, BV, TUV) for extreme cold region projects
- Welding procedure qualification for ultra-low temperature steel applications
- ISO 9001 and CE certification (when required for export to cold climate countries)
- Special certification for high-altitude/cold region applications (when required)
All Q370qE plates undergo 100% ultrasonic testing and additional -40°C impact testing to ensure internal quality for extreme cold-region heavy-load applications.
Key Advantages of Q370qE
Superior High-Strength Performance
370MPa yield strength provides exceptional load-bearing capacity for heavy-load bridge applications in extreme cold regions.
Exceptional Ultra-Low Temperature Toughness
Maintains superior toughness at -40°C, ideal for extreme cold climate regions in northern/northeastern China and high-altitude areas.
Enhanced Weldability
Lower carbon equivalent (0.45%) and optimized chemistry ensure excellent welding performance even in extreme cold construction conditions.
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