Q420qD Bridge Steel Plate
High-strength structural steel designed for bridge engineering, compliant with GB/T 714-2015, offering excellent durability and reliability at -20°C low-temperature environment.
About Q420qD Bridge Steel Plate
Q420qD is a high-strength low-alloy structural steel under Chinese standard (GB/T 714-2015), specially developed for large-span bridge engineering projects in low-temperature environments.
The letter "q" in the grade stands for "qiaoliang" (bridge), and "D" indicates the steel's impact test temperature is -20°C, suitable for large-span bridge construction projects in cold regions of China and worldwide.
This steel features high yield strength (420MPa), excellent weldability, and outstanding low-temperature toughness, making it an ideal choice for large-span bridge infrastructure projects in cold climate zones.
Technical Specifications
Basic Information
Mechanical Properties
| Thickness(mm) | Yield Strength(MPa) ≥ | Tensile Strength(MPa)≥ | Elongation(%) ≥ | Impact Energy(J) ≥ |
|---|---|---|---|---|
| ≤50 | 420 | 540 | 19 | 120 |
| ＞50--≤100 | 410 | 540 | 19 | 120 |
| ＞100--≤150 | - | 540 | 19 | 120 |
Chemical Composition (TMCP)
| Grade | Quality | C ≤% | Si ≤% | Mn % | Nb % | V % | Ti % | Als % | Cr ≤% | Ni ≤% | Cu ≤% | Mo ≤% | N ≤% |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Q420q | D | 0.11 | 0.55 | 1.00~1.70 | 0.010~0.090 | 0.010~0.080 | 0.006~0.030 | 0.010~0.045 | 0.5 | 0.3 | 0.3 | 0.2 | 0.008 |
a: Max Mn can be 2.00% by agreement.
b: Al, Nb, V, Ti can be added alone or in combination. Nb+V+Ti ≤ 0.22%.
c: Total aluminum (Alt): 0.015%~0.050%.
International Standard Comparison
Mechanical Properties Comparison (Thickness ≤50mm)
| Property | Q420qD | S420NL | A709 Gr50 |
|---|---|---|---|
| Min Yield Strength (MPa) | 420 | 420 | 345 |
| Tensile Strength (MPa) | 540 | 520-680 | 450-600 |
| Min Elongation (%) | 19 | 21 | 21 |
| Impact Test Temperature (°C) | -20 | -20 | 0 |
Chemical Composition Comparison (%)
| Element | Q420qD | S420NL | A709 Gr50 |
|---|---|---|---|
| Carbon (C) | ≤0.11 | ≤0.22 | ≤0.23 |
| Silicon (Si) | ≤0.55 | ≤0.60 | 0.15-0.40 |
| Manganese (Mn) | 1.00-1.70 | 1.40-1.90 | 0.90-1.60 |
Key Differences Summary:
- Q420qD offers high yield strength (420MPa) with excellent -20°C low-temperature toughness
- Designed for large-span bridge projects in cold climate regions
- Excellent weldability with Ceq ≤ 0.44%
- Compliant with GB/T 714-2015 standard
Application Projects
Large-span Highway Bridge
Ideal for large-span highway bridges in cold regions, providing excellent low-temperature stability at -20℃.
- Plate Thickness: 16mm-60mm
- Total Consumption: 12,800 tons
High-speed Railway Bridge
Applied to large-span high-speed railway bridges in cold zones, featuring outstanding -20℃ low-temperature fatigue resistance.
- Total Consumption: 18,500 tons
- 100+ years service life
Large-span Urban Viaduct
Used for large-span urban viaducts in cold regions, offering reliable -20℃ structural support.
- Plate Thickness: 20mm-80mm
- High load-bearing capacity
Frequently Asked Questions (FAQ)
What is the difference between Q420qD and Q420qE/Q420qF steel plates?
Main differences between Q420qD, Q420qE and Q420qF bridge steel plates:
- Impact Test Temperature: Q420qD (-20°C) < Q420qE (-40°C) < Q420qF (-60°C)
- Low-Temperature Performance: Q420qF > Q420qE > Q420qD
- Application: Q420qD for normal temperature areas, Q420qE for cold areas, Q420qF for extremely cold areas
- Strength Level: All grades feature 420MPa high yield strength for large-span bridges
- Application Scope: Q420qD is the most widely used grade for general cold region large-span bridges
What are the welding requirements for Q420qD steel plates?
Q420qD has good weldability (Ceq ≤0.44%) with cold-region construction requirements:
- Preheating to 80-120℃ recommended for thickness >30mm
- Use E55 series low-alloy electrodes (E5515/E5516) for conventional welding
- Interpass temperature control ≤230℃ during multi-pass welding
- Post-weld heat treatment not required for general bridge components
- Suitable for automated welding and on-site construction
Follow standard welding procedures for Q420 series high-strength structural steels.
What is the operating temperature range of Q420qD steel?
Q420qD is designed for low temperature 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
- Application Environment: Suitable for cold regions in China and worldwide
Q420qD is a high-strength bridge steel for large-span bridge projects in cold climate zones.
What advantages does Q420qD have for large-span bridge construction?
Q420qD has outstanding advantages for large-span bridge construction:
- High yield strength: 420MPa, suitable for large-span bridge load-bearing requirements
- Excellent low-temperature toughness: Stable performance at -20°C
- Good weldability: Suitable for large-scale bridge construction
- Wide application: Ideal for highway, high-speed railway, large-span urban bridges
- Cost-effective: Balanced performance and cost for cold region projects
- National standard certification: Fully compliant with GB/T 714-2015 bridge steel standards
These advantages make Q420qD the optimal choice for large-span bridge engineering in cold climate zones.
What quality inspections are performed for Q420qD steel plates?
Comprehensive quality inspections are provided for Q420qD 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 in accordance with national standard
- Third-party inspection certification available upon request
All Q420qD steel plates undergo strict quality inspections to ensure bridge engineering compliance.
Core Advantages
420MPa High Yield Strength
Superior load-bearing capacity for large-span bridges.
Excellent Weldability
Optimized composition ensures reliable welding performance.
-20℃ Low-Temperature Toughness
Stable performance in cold climate environments.
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