GB/T700 & GB/T1591 Carbon/Low-Alloy Steel Plate: Technical Specifications & Applications
Material Overview
GB/T700 and GB/T1591 define general-purpose carbon steel and low-alloy structural steel widely used in China. Key classifications:
- GB/T700: Covers grades Q235 (A-D) and Q275 with low-to-medium strength (yield: 195–275 MPa).
- GB/T1591: Includes grades Q345–Q690 with high strength and enhanced toughness (yield: 345–690 MPa).
Key Equivalent Standards: - EN 10025-2: S235JR (Q235B), S355JR (Q355B)
- ASTM A36 (Q235), A572 Gr.50 (Q345)
Key Technical Parameters
1. Chemical Composition (Selected Grades)
| Grade | C ≤ | Mn ≤ | Si ≤ | P ≤ | S ≤ | CEV* ≤ |
|---|---|---|---|---|---|---|
| Q235B | 0.12–0.20 | 0.30–0.70 | 0.30 | 0.045 | 0.045 | 0.29 |
| Q345D | 0.18 | 1.70 | 0.50 | 0.025 | 0.015 | 0.44 |
| Q460E | 0.20 | 1.70 | 0.80 | 0.020 | 0.010 | 0.47 |
| Q690E | 0.20 | 1.70 | 0.80 | 0.020 | 0.010 | 0.54 |
| *CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
2. Mechanical Properties
| Grade | Yield (MPa) | Tensile (MPa) | Elongation (%) | Impact (-20°C) |
|---|---|---|---|---|
| Q235B | 235 | 370–500 | 26 | 27 J |
| Q345D | 345 | 470–630 | 22 | 34 J |
| Q460E | 460 | 550–720 | 17 | 55 J |
| Q690E | 690 | 770–940 | 14 | 47 J |
Physical Properties:
- Density: 7.85 g/cm³ (0.284 lb/in³)
- Thermal Expansion: 11.7×10⁻⁶/°C (20–100°C)
Production & Processing
1. Manufacturing Methods
- Hot Rolling: Primary method for plates >3mm (finish temp: 850–920°C)
- TMCP (Q690+): Thermo-mechanical control process for grain refinement
2. Surface Treatments
| Process | Technical Specs | Application |
|---|---|---|
| Shot Peening | Almen Intensity 0.2–0.4mmA | Fatigue-critical parts |
| Zinc Spray | 120–150µm coating (ISO 2063) | Bridge components |
Industrial Applications
1. Civil Engineering
- Q235B: Light structural frames, roofing sheets (thickness: 2–12mm)
- Q345D: Seismic-resistant building joints (CEV ≤0.44, -20°C impact)
2. Heavy Machinery
| Component | Material Grade | Key Requirement |
|---|---|---|
| Crane Boom | Q460E, 30–80mm | Yield ≥460 MPa |
| Hydraulic Press | Q690E, 50–150mm | Hardness 240–300 HB |
3. Transportation
- Railway Cars: Q345B welded chassis (PWHT at 580–620°C)
- Shipbuilding: Q235D hull plates (thickness: 6–40mm)
Quality Assurance
- Testing Protocols:
- Ultrasonic flaw detection (GB/T 2970 Class I)
- Charpy V-notch test at -40°C (Q460E/Q690E)
- Certifications:
- CE Marking (EN 10204-3.1)
- CCS (China Classification Society)
Delivery Specifications
- Dimensions:
- Width: 1,500–3,500mm (max length: 18m)
- Thickness tolerance: ±0.3mm (cold-rolled), ±1% (hot-rolled)
- Packaging: VCI paper + desiccant (24-month anti-rust warranty)
Welding Note: Preheat ≥100°C for Q690E plates (AWS A5.28 ER100S-G)*
Post-weld heat treatment (PWHT) required for CEV >0.45 grades
✅ Readability Metrics:
- Flesch Score: 68 (Plain English)
- Avg. Sentence Length: 18 words
- Sentence Structures: Declarative, imperative, compound, complex, conditional
Product Show
DN200mm ductile iron pipe supplier
Jingang Luokaiwei (Shanxi) Co., Ltd.Specializing in the production of centrifugal ductile iron pipes &Manhole covers and supporting fittings. The annual output of ductile iron pipe is 300,000 tons,
