Q550qD Bridge Steel Plate
High-strength structural steel designed for long-span bridge engineering, compliant with GB/T 714-2015, offering excellent durability and reliability at -20°C low-temperature environment.
About Q550qD Bridge Steel Plate
Q550qD is a high-strength low-alloy structural steel under Chinese standard (GB/T 714-2015), specially developed for large-span bridge engineering in cold regions.
The letter "q" in the grade stands for "qiaoliang" (bridge), and "D" indicates the steel's impact test temperature is -20°C, suitable for long-span bridge construction projects in cold regions of China and worldwide.
This steel features higher reliable strength (yield strength 550MPa), excellent weldability, and outstanding low-temperature toughness, making it the optimal choice for long-span bridge infrastructure projects in -20°C low-temperature environments.
Technical Specifications
Basic Information
Mechanical Properties
| Thickness(mm) | Yield Strength(MPa) ≥ | Tensile Strength(MPa)≥ | Elongation(%) ≥ | Impact Energy(J) ≥ |
|---|---|---|---|---|
| ≤50 | 550 | 660 | 16 | 120 |
| ＞50--≤100 | 530 | 660 | 16 | 120 |
| ＞100--≤150 | - | 660 | 16 | 120 |
Q550qD Chemical composition of tempered steel (Mass Fraction %)
| Element | C ≤ | Si ≤ | Mn | Nb | V | Ti | Als | Cr ≤ | Ni ≤ | Cu ≤ | Mo ≤ | N ≤ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Content | 0.12 | 0.55 | 0.80-1.70 | 0.005-0.060 | 0.010-0.080 | 0.006-0.030 | 0.010-0.045 | 0.80 | 0.70 | 0.30 | 0.30 | 0.008 |
Note: Carbon Equivalent (Ceq) ≤ 0.44%, Welding Carbon Equivalent (Pcm) ≤ 0.24%. Optimized chemical composition balances higher reliable strength (550MPa yield strength) with -20°C low-temperature toughness, ideal for cold region long-span bridge applications.
International Standard Comparison
Mechanical Properties Comparison (Thickness ≤50mm)
| Property | Q550qD (GB/T 714-2015) | S550NL (EN 10025) | A709 Gr55 (ASTM A709) |
|---|---|---|---|
| Min Yield Strength (MPa) | 550 | 550 | 380 (55 ksi) |
| Tensile Strength (MPa) | 660 | 660 | 490-655 (71-95 ksi) |
| Min Elongation (%) | 16 | 19 | 21 |
| Impact Test Temperature (°C) | -20 | -40 | -20°C |
Chemical Composition Comparison (%)
| Element | Q550qD (Max/Range) | S550NL (EN 10025) (Max/Range) | A709 Gr55 (ASTM A709) (Max/Range) |
|---|---|---|---|
| Carbon (C) | ≤0.12 | ≤0.22 | ≤0.23 |
| Silicon (Si) | ≤0.55 | ≤0.60 | 0.15-0.40 |
| Manganese (Mn) | 0.80-1.70 | 1.40-1.90 | 0.90-1.60 |
Key Differences Summary:
- Q550qD offers higher yield strength (550MPa) with excellent -20°C low-temperature toughness
- Stricter impurity limits ensure superior performance in cold environments
- Impact test temperature of -20°C, designed for cold region long-span bridge construction
- Optimized carbon equivalent (Ceq ≤ 0.44%) and welding carbon equivalent (Pcm ≤ 0.24%) maintain excellent weldability in low-temperature environments
- High-strength solution for long-span bridges in cold climate regions
- Strict quality control meets GB/T 714-2015 standard requirements for cold region bridge steel
Application Projects
Cold Region Long-Span Highway Bridge
Used for long-span highway bridges in cold regions, providing excellent low-temperature toughness and structural stability at -20°C environment.
- Plate Thickness: 25mm-70mm
- Total Consumption: 24,800 tons
- Suitable for -20°C low-temperature environments
Cold Region Long-Span Railway Bridge Project
Applied to long-span railway bridges in cold climate areas, featuring outstanding fatigue resistance and stable low-temperature mechanical properties.
- Total Consumption: 31,200 tons
- 100-year design life in cold environments
Cold Region Urban Long-Span Viaduct Project
Used for long-span urban viaduct bridges in northern cold cities, offering reliable structural support and excellent low-temperature performance.
- Plate Thickness: 35mm-75mm
- Total Consumption: 26,300 tons
- Excellent weldability in low temperatures
Other Typical Applications
Frequently Asked Questions (FAQ)
What is the difference between Q550qD and Q550qE/Q550qF steel plates?
Main differences between Q550qD, Q550qE and Q550qF bridge steel plates:
- Impact Test Temperature: Q550qD (-20°C) < Q550qE (-40°C) < Q550qF (-60°C)
- Impurity Limits: Q550qD (P≤0.012%/S≤0.008%) > Q550qE > Q550qF (stricter control)
- Application: Q550qD for cold long-span bridges, Q550qE for extremely cold, Q550qF for ultra-cold
- Low-Temperature Performance: Q550qD has good toughness at -20°C low temperature
- Environment Adaptability: Q550qD for cold climate long-span projects
What are the welding requirements for Q550qD steel plates?
Q550qD has excellent weldability (Ceq ≤0.44%) with low-temperature special requirements:
- Preheat to 150-200°C when ambient temperature <0°C for all thicknesses
- Preheat to 200-250°C for thickness >40mm at normal temperatures
- Use E70 series low-alloy electrodes (E7015/E7016-G) for cold environments
- Interpass temperature control 200-250°C during multi-pass welding
- Post-weld slow cooling and insulation required in ambient temperature < -10°C conditions
- Optimized for reliable welding joints in -20°C low-temperature construction
Follow strict cold region welding procedures for Q550D series high-strength structural steels.
What is the operating temperature range of Q550qD steel?
Q550qD is designed for cold climate environments with the following temperature range:
- Minimum Operating Temperature: -20°C (meets impact energy requirements at this temperature)
- Recommended Continuous Operating Temperature: -20°C ~ 200°C
- Short-term Maximum Operating Temperature: 300°C
- Optimal Welding Temperature: Preheating required below 0°C
- Storage/Transport Temperature: Suitable for cold winter conditions
Q550qD is the preferred high-strength bridge steel for cold region long-span infrastructure projects.
What advantages does Q550qD have for cold region long-span bridge construction?
Q550qD has outstanding advantages for cold region long-span bridge construction:
- Higher yield strength (550MPa) for long-span bridge load-bearing requirements
- Excellent -20°C low-temperature toughness prevents brittle fracture
- Stricter impurity control for superior cold environment reliability
- Optimized composition ensures stable performance in cold climates
- Excellent weldability even in cold construction conditions
- Perfect for northern China cold and global cold climate long-span bridge projects
- Complies with GB/T 714-2015 cold region bridge steel standards
These advantages make Q550qD the first choice for high-strength long-span bridge engineering in cold climate regions.
What quality inspections are performed for Q550qD steel plates?
Comprehensive quality inspections are provided for Q550qD steel plates:
- EN 10204 3.1 material test certificate with -20°C impact test results
- GB/T 714-2015 cold region bridge steel compliance certification
- 100% ultrasonic testing for internal quality inspection
- Mechanical property test including yield and tensile strength
- -20°C Charpy V-notch impact toughness test report
- Chemical composition analysis with stricter impurity limits
- Third-party inspection certification available upon request
All Q550qD steel plates undergo strict cold-region quality inspections to ensure compliance.
Core Advantages of Q550qD
-20°C Low-Temperature Toughness
Superior low-temperature performance, ideal for cold region long-span bridge engineering.
Excellent Cold Weldability
Optimized carbon equivalent ensures reliable welding performance even in -20°C low-temperature conditions.
Cold Region Specialization
Specifically designed for long-span bridge construction in northern cold zones and cold climate regions worldwide.
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