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Q235B碳钢方管: 尺寸, 房产及购买指南
A Q235B carbon steel square tube is the workhorse hollow section of steel construction: strong, straight, easy to weld and economical. This guide explains what Q235B square tube is, its chemical and mechanical properties, standard sizes, and how to specify it correctly for your project. All sizes below are available as Q235B carbon steel square tube from QIDAMT, with mill certificates and third-party inspection on request.
What Is Q235B Square Tube?
Q235B square tube is a cold-formed welded hollow section made from hot-rolled or cold-rolled Q235B strip, normally produced to 国标/T 6728 (cold-formed welded hollow sections) with the base material to 国标/T 700. The tube is formed, high-frequency welded and then sized to tight dimensional tolerances. Square and rectangular hollow sections (SHS/RHS) offer excellent strength-to-weight ratio and torsional rigidity, making them preferred over solid bars for many structural applications.
化学成分 (Q235B Base Material)
| 元素 | C | 和 | 锰 | 磷 | S |
|---|---|---|---|---|---|
| Max (%) | 0.20 | 0.35 | 1.40 | 0.045 | 0.045 |
机械性能
- 屈服强度: ≥ 235 兆帕
- 抗拉强度: 370 – 500 兆帕
- 伸长: ≥ 26 %
- Impact energy (20 ℃): ≥ 27 J
- 硬度: ≈ 121 HBW
Standard Square Tube Sizes
| 尺寸 (毫米) | Wall (毫米) | Weight (kg/m) |
|---|---|---|
| 20 × 20 | 1.0 – 2.0 | 0.60 – 1.13 |
| 40 × 40 | 1.5 – 3.0 | 1.82 – 3.48 |
| 50 × 50 | 1.5 – 4.0 | 2.28 – 5.77 |
| 60 × 60 | 2.0 – 4.0 | 3.64 – 7.04 |
| 80 × 80 | 2.0 – 5.0 | 4.91 – 11.78 |
| 100 × 100 | 2.0 – 6.0 | 6.17 – 17.72 |
| 120 × 120 – 200 × 200 | 3.0 – 10.0 | 11.03 – 59.94 |
Standard lengths are 6 米和 12 米. Rectangular hollow sections (RHS) and custom sizes can also be produced to your drawing. For galvanized requirements, ask about our galvanized square and rectangular tube.
应用领域
Q235B square tube is used in steel structures, portal frames, mezzanines, 扶手, 盖茨, 栅栏, agricultural machinery, 拖车, racks, solar mounting frames and furniture frames. Its closed cross-section resists bending and torsion far better than an open section of the same weight — which is why structural engineers choose it for columns and chord members. Where open sections are preferred, see our Q235B equal angle bar 和 Q235B steel channel ranges.
How to Specify Square Tube Correctly
- State outside dimension × wall thickness × length, e.g. “80 × 80 × 3.0 毫米× 6 米”.
- Specify the standard (国标/T 6728 or your local equivalent, e.g. 在 10219 / ASTM A500) if your design requires it.
- Decide the surface: 黑色的 (磨), pre-galvanized or hot-dip galvanized.
- Confirm the corner type — square corner or radius corner — if appearance matters for furniture or architecture.
- Request the mill test certificate and, for critical projects, third-party inspection (SGS/BV/TUV).
Tell us the sizes, quantities and destination port — we will confirm price, stock and shipping within 24 hours.
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