Carbon SteelPipe/Tube
Overview
Q345 hollow square tube is a welded or seamless structural steel tube with a square cross-section, made from Q345 low-alloy high-strength structural steel. It is widely used in construction, infrastructure, machinery, and engineering applications due to its high strength, good toughness, excellent weldability, and cost-effectiveness. Under the updated GB/T 1591-2018 standard, Q345 has been officially replaced by Q355, though Q345 remains widely referenced and used in practice.
Size Range
- 20 Γ 20,thk1.2 β 2.0
- 25 Γ 25,thk1.5 β 2.5
- 30 Γ 30,thk1.5 β 3.0
- 40 Γ 40,thk1.5 β 4.0
- 50 Γ 50,thk1.5 β 5.0
- 60 Γ 60,thk2.0 β 6.0
- 70 Γ 70,thk2.0 β 6.0
- 80 Γ 80,thk2.5 β 8.0
- 100 Γ 100,thk3.0 β 10.0
- 120 Γ 120,thk4.0 β 12.0
- 150 Γ 150,thk4.0 β 14.0
- 180 Γ 180,thk5.0 β 16.0
- 200 Γ 200,thk5.0 β 16.0
- 250 Γ 250,thk6.0 β 20.0
- 300 Γ 300,thk6.0 β 22.0
- 350 Γ 350,thk8.0 β 25.0
- 400 Γ 400,thk8.0 β 25.0
Grade Specification
| System | Value |
|---|---|
| π¨π³ GB | Q355 (per GB/T 1591-2018) |
| πͺπΊ EN | S355J2H / S355JOH |
| πΊπΈ ASTM | A500 Gr. B / A500 Gr. C |
| π―π΅ JIS | STKR 400 / STKR 490 |
| π·πΊ GOST | 09G2S |
| π¦πΊ AS | C350 / C450 |
Chemical Composition
| Element | Value |
|---|---|
| C | β€ 0.20 |
| Si | β€ 0.55 |
| Mn | 1.00β1.60 |
| P | β€ 0.045 |
| S | β€ 0.045 |
| V | 0.02β0.15 |
| Nb | 0.015β0.060 |
| Ti | 0.02β0.20 |
| Alt | β |
| Cr | β€ 0.30 |
| Ni | β€ 0.50 |
Mechanical Properties
| Property | Value |
|---|---|
| Yield Strength (MPa), t β€ 16 mm | β₯ 345 |
| Yield Strength (MPa), 16 < t β€ 35 mm | β₯ 325 |
| Yield Strength (MPa), 35 < t β€ 50 mm | β₯ 295 |
| Tensile Strength (MPa) | 470β630 |
| Elongation (%) | β₯ 21 |
| Impact Energy (J) | β |
Physical Properties
| Property | Unit | Value |
|---|---|---|
| Density (g/cmΒ³) | g/cmΒ³ | 7.85 |
| Melting Point (Β°C) | Β°C | ~1490 |
| Modulus of Elasticity (GPa) | GPa | 206 |
| Modulus of Rigidity (GPa) | - | 79.3 |
| Poisson's Ratio | - | 0.30 |
| Coefficient of Thermal Expansion (Β΅m/mΒ·Β°C, 20β100Β°C) | Γ10β»βΆ/K | 12.0 |
| Thermal Conductivity (W/mΒ·K, 25Β°C) | W/mΒ·K | 46.0 |
| Specific Heat (J/kgΒ·K) | J/kgΒ·K | 460 |
| Electrical Resistivity (nΩ·m, 25°C) | μΩ·cm | 156 |
Applications
- Construction & Infrastructure
- Industrial Engineering
- Oil & Gas & Energy
- Transportation
- Machinery
- Architectural