Q345qD 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 Q345qD Bridge Steel Plate
Q345qD is a high-strength low-alloy structural steel under Chinese standard (GB/T 714-2015), specially developed for 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 bridge construction projects in cold regions of China and worldwide.
This steel features reliable strength (yield strength 345MPa), excellent weldability, and outstanding low-temperature toughness, making it an ideal choice for 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 | 345 | 490 | 20 | 120 |
| ＞50--≤100 | 335 | 490 | 20 | 120 |
| ＞100--≤150 | 305 | 490 | 20 | 120 |
Chemical Composition (Hot-rolled/Normalized)
| Grade | Quality | C ≤% | Si ≤% | Mn % | Nb % | V % | Ti % | Als % | Cr ≤% | Ni ≤% | Cu ≤% | N ≤% |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Q345q | D | 0.18 | 0.55 | 0.90~1.60 | 0.005~0.060 | 0.010~0.080 | 0.006~0.030 | 0.010~0.045 | 0.3 | 0.3 | 0.3 | 0.008 |
a: Al, Nb, V, Ti can be added alone or in combination. Nb+V+Ti ≤ 0.22%.
b: Total aluminum (Alt): 0.015%~0.050%.
Chemical Composition (TMCP)
| Grade | Quality | C ≤% | Si ≤% | Mn % | Nb % | V % | Ti % | Als % | Cr ≤% | Ni ≤% | Cu ≤% | Mo ≤% | N ≤% |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Q345q | D | 0.14 | 0.55 | 0.90~1.60 | 0.010~0.090 | 0.010~0.080 | 0.006~0.030 | 0.010~0.045 | 0.3 | 0.3 | 0.3 | - | 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 | Q345qD | S355NL | A709 Gr36 |
|---|---|---|---|
| Min Yield Strength (MPa) | 345 | 355 | 250 |
| Tensile Strength (MPa) | 490 | 470-630 | 400-550 |
| Min Elongation (%) | 20 | 22 | 20 |
| Impact Test Temperature (°C) | -20 | -20 | 0 |
Chemical Composition Comparison (%)
| Element | Q345qD | S355NL | A709 Gr36 |
|---|---|---|---|
| Carbon (C) | ≤0.18 | ≤0.22 | ≤0.21 |
| Silicon (Si) | ≤0.55 | ≤0.60 | 0.15-0.40 |
| Manganese (Mn) | 0.90-1.60 | 1.40-1.90 | 0.90-1.60 |
Key Differences Summary:
- Q345qD offers reliable yield strength (345MPa) with excellent -20°C low-temperature toughness
- Designed for bridge projects in cold climate regions
- Excellent weldability with Ceq ≤ 0.42%
- Compliant with GB/T 714-2015 standard
Application Projects
Cold Region Highway Bridge
Ideal for medium and small-span highway bridges in cold regions, providing excellent low-temperature stability.
- Plate Thickness: 12mm-50mm
- Total Consumption: 8,600 tons
Cold Area Railway Bridge
Applied to medium-span railway bridges in cold zones, featuring outstanding low-temperature fatigue resistance.
- Total Consumption: 12,300 tons
- 50-100 years service life
Northern Urban Viaduct
Used for urban viaducts in northern cold regions, offering reliable low-temperature structural support.
- Plate Thickness: 16mm-60mm
- Excellent low-temperature toughness
Frequently Asked Questions (FAQ)
What is the difference between Q345qD and Q345qC/Q345qE steel plates?
Main differences between Q345qC, Q345qD and Q345qE bridge steel plates:
- Impact Test Temperature: Q345qC (0°C) < Q345qD (-20°C) < Q345qE (-40°C)
- Low-Temperature Performance: Q345qE > Q345qD > Q345qC (higher toughness at lower temperature)
- Application: Q345qC for normal temperature areas, Q345qD for cold areas, Q345qE for extremely cold areas
- Price & Cost: Q345qD is moderately priced, balancing performance and cost for cold region projects
- Impurity Limits: Stricter than Q345qC, slightly more lenient than Q345qE
What are the welding requirements for Q345qD steel plates?
Q345qD has excellent weldability (Ceq ≤0.42%) with cold-region construction requirements:
- Preheating not required for thickness ≤30mm at ambient temperature ≥-20℃
- Preheat to 80-120℃ for thickness >30mm or ambient temperature <-20℃
- Use E50 series low-alloy electrodes (E5015/E5016) for conventional welding
- Interpass temperature control ≤250℃ during multi-pass welding
- Post-weld heat treatment not required for general bridge components
- Suitable for welding construction in low-temperature environments
Follow standard welding procedures for Q345 series high-strength structural steels in cold regions.
What is the operating temperature range of Q345qD steel?
Q345qD is designed for cold 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 northern China and worldwide
- Storage/Transport Temperature: Adaptable to conventional and low-temperature environments
Q345qD is the preferred high-strength bridge steel for cold climate bridge projects.
What advantages does Q345qD have for cold region bridge construction?
Q345qD has outstanding advantages for cold region bridge construction:
- Excellent low-temperature toughness: Stable performance at -20°C, preventing brittle fracture
- Reliable strength: 345MPa yield strength meets cold region bridge load-bearing requirements
- Good weldability in low temperatures: Suitable for on-site construction in cold climates
- Wide application: Ideal for highway, railway, urban bridges in northern cold regions
- Cost-performance balance: Lower cost than Q345qE while meeting cold region requirements
- National standard certification: Fully compliant with GB/T 714-2015 bridge steel standards
- Stable quality: Mature production process for low-temperature bridge steel
These advantages make Q345qD the first choice for bridge engineering in cold climate zones.
What quality inspections are performed for Q345qD steel plates?
Comprehensive quality inspections are provided for Q345qD 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 Q345qD steel plates undergo strict quality inspections to ensure cold region engineering compliance.
Core Advantages
-20℃ Low-Temperature Toughness
Outstanding performance in cold climate environments.
Excellent Weldability
Optimized carbon equivalent ensures easy welding.
Cold Region Adaptability
Perfect for bridge projects in northern cold areas.
Request a Quote
Reply within 12h: customize@cehesteel.com