Q620qD 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 Q620qD Bridge Steel Plate
Q620qD 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 ultra-high reliable strength (yield strength 620MPa), 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 | 620 | 720 | 15 | 120 |
| ＞50--≤100 | 580 | 720 | 15 | 120 |
| ＞100--≤150 | - | 720 | 15 | 120 |
Q620qD Chemical composition of tempered steel (Mass Fraction %)
| Element | C ≤ | Si ≤ | Mn | Nb | V | Ti | Als | Cr ≤ | Ni ≤ | Cu ≤ | Mo ≤ | N ≤ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Content | 0.14 | 0.55 | 0.80-1.70 | 0.005-0.090 | 0.010-0.080 | 0.006-0.030 | 0.010-0.045 | 0.40-0.80 | 0.25-1.00 | 0.15-0.55 | 0.20-0.50 | 0.008 |
Note: Carbon Equivalent (Ceq) ≤ 0.46%, Welding Carbon Equivalent (Pcm) ≤ 0.25%. Optimized chemical composition balances ultra-high reliable strength (620MPa 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 | Q620qD (GB/T 714-2015) | S620NL (EN 10025) | A709 Gr65 (ASTM A709) |
|---|---|---|---|
| Min Yield Strength (MPa) | 620 | 620 | 450 (65 ksi) |
| Tensile Strength (MPa) | 720 | 720 | 530-690 (77-100 ksi) |
| Min Elongation (%) | 15 | 18 | 20 |
| Impact Test Temperature (°C) | -20 | -20 | -20°C |
Chemical Composition Comparison (%)
| Element | Q620qD (Max/Range) | S620NL (EN 10025) (Max/Range) | A709 Gr65 (ASTM A709) (Max/Range) |
|---|---|---|---|
| Carbon (C) | ≤0.14 | ≤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:
- Q620qD offers ultra-high yield strength (620MPa) 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 ≤ 0.46%) and welding carbon equivalent (Pcm ≤ 0.25%) maintain excellent weldability
- Ultra-high-strength solution for long-span bridges in cold climate regions
- Strict quality control meets GB/T 714-2015 standard requirements for 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: 28,500 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: 35,600 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: 29,400 tons
- Excellent weldability in low temperatures
Other Typical Applications
Frequently Asked Questions (FAQ)
What is the difference between Q620qD and Q620qE/Q620qC steel plates?
Main differences between Q620qD, Q620qE and Q620qF bridge steel plates:
- Impact Test Temperature: Q620qD (-20°C) < Q620qE (-40°C) < Q620qF (-60°C)
- Impurity Limits: Q620qD (P≤0.015%/S≤0.010%) < Q620qE (stricter) < Q620qF (strictest control)
- Application: Q620qD for normal regions, Q620qE for cold regions, Q620qF for extremely cold regions
- Low-Temperature Performance: Q620qD has excellent toughness at -20°C low temperature
- Environment Adaptability: Q620qD for cold climate long-span projects
What are the welding requirements for Q620qD steel plates?
Q620qD has excellent weldability (Ceq ≤0.46%) with special requirements:
- Preheat to 180-220°C when ambient temperature <0°C for all thicknesses
- Preheat to 220-260°C for thickness >40mm at normal temperatures
- Use E7018-G/E8015-G low-alloy electrodes for high-strength welding
- Interpass temperature control 220-260°C during multi-pass welding
- Post-weld slow cooling and insulation required in ambient temperature < -20°C conditions
- Optimized for reliable welding joints in cold environment construction
Follow strict cold region welding procedures for Q620D series ultra-high-strength structural steels.
What is the operating temperature range of Q620qD steel?
Q620qD 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
Q620qD is the preferred ultra-high-strength bridge steel for cold region long-span infrastructure projects.
What advantages does Q620qD have for cold region long-span bridge construction?
Q620qD has outstanding advantages for cold region long-span bridge construction:
- Ultra-high yield strength (620MPa) for super 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 low-temperature construction conditions
- Perfect for northern China cold and global cold climate long-span bridge projects
- Complies with GB/T 714-2015 bridge steel standards
These advantages make Q620qD the first choice for ultra-high-strength long-span bridge engineering in cold climate regions.
What quality inspections are performed for Q620qD steel plates?
Comprehensive quality inspections are provided for Q620qD steel plates:
- EN 10204 3.1 material test certificate with -20°C impact test results
- GB/T 714-2015 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 Q620qD steel plates undergo strict cold-region quality inspections to ensure compliance.
Core Advantages of Q620qD
-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.
Ultra-High Strength (620MPa)
620MPa ultra-high yield strength, perfect for super long-span bridge construction in cold zones.
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