ASTM A554 is the American standard for welded stainless steel mechanical tubing in round, square, and rectangular shapes. It is specifically designed for mechanical and structural applications – not for pressure service (use ASTM A269 or A312 for pressure).
Square tubes under ASTM A554 are produced as cold-formed welded tubes from stainless steel strips, then heat-treated and finished to meet mechanical property requirements. The standard covers multiple stainless steel grades, with 304 and 316 being the most common.
| Quick Facts | Value |
|---|---|
| Standard | ASTM A554 |
| Shape | Square |
| Process | Cold-formed + welded + heat treated |
| Key Feature | Corrosion resistance + structural strength |
| Primary Use | Architectural, handrails, furniture, frames |
| Common Grades | 304, 304L, 316, 316L |
ASTM A554 references standard stainless steel compositions per ASTM A240. Below are the most common grades.
| Element | Grade 304 | Grade 304L | Grade 316 | Grade 316L |
|---|---|---|---|---|
| Carbon (C) | ≤ 0.08 | ≤ 0.035 | ≤ 0.08 | ≤ 0.035 |
| Chromium (Cr) | 18.0–20.0 | 18.0–20.0 | 16.0–18.0 | 16.0–18.0 |
| Nickel (Ni) | 8.0–10.5 | 8.0–12.0 | 10.0–14.0 | 10.0–14.0 |
| Molybdenum (Mo) | — | — | 2.00–3.00 | 2.00–3.00 |
| Manganese (Mn) | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 |
Grade Selection Guide:
| Grade | Key Feature | Typical Application |
|---|---|---|
| 304 | General-purpose, good corrosion resistance | Handrails, furniture, frames |
| 304L | Low carbon, better weldability | Welded structures, thin walls |
| 316 | Contains molybdenum, excellent corrosion resistance | Marine, coastal, chemical exposure |
| 316L | Low carbon + molybdenum | Marine welded structures |
ASTM A554 specifies mechanical property requirements based on the tube size (wall thickness) and heat treatment condition.
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 304 | ≥ 515 | ≥ 205 | ≥ 35 |
| 304L | ≥ 485 | ≥ 170 | ≥ 35 |
| 316 | ≥ 515 | ≥ 205 | ≥ 35 |
| 316L | ≥ 485 | ≥ 170 | ≥ 35 |
Elongation measured in 50 mm (2 inches). Values are minimum requirements per ASTM A554.
ASTM A554 tubes can be supplied in multiple conditions:
| Condition | Description | Application |
|---|---|---|
| As-welded | No heat treatment after welding | Non-critical, economy applications |
| Annealed | Full solution annealing | Maximum corrosion resistance and ductility |
| Stress-relieved | Low-temperature heat treatment | Reduced residual stress, good strength |
Recommended: For architectural and structural applications, annealed condition provides the best combination of corrosion resistance and mechanical properties.
| Parameter | Typical Tolerance |
|---|---|
| Outside dimensions | ± 0.4 mm to ± 0.8 mm (size dependent) |
| Wall thickness | ± 10% |
| Straightness | ≤ 1.0 mm per meter |
| Twist | ≤ 1° + 0.5° per meter |
| Corner radius | 1.5* to 2.5* wall thickness (typical) |
| Size (mm) | Common Wall Thickness (mm) |
|---|---|
| 10 * 10 | 0.8, 1.0, 1.2 |
| 20 * 20 | 1.0, 1.5, 2.0 |
| 25 * 25 | 1.5, 2.0, 2.5 |
| 30 * 30 | 1.5, 2.0, 2.5, 3.0 |
| 40 * 40 | 1.5, 2.0, 2.5, 3.0 |
| 50 * 50 | 2.0, 2.5, 3.0, 4.0 |
| 60 * 60 | 2.0, 2.5, 3.0, 4.0 |
| 80 * 80 | 2.5, 3.0, 4.0, 5.0 |
| 100 * 100 | 3.0, 4.0, 5.0, 6.0 |
Custom sizes and thicknesses available upon request.
Primary Use: Architectural and decorative structural applications
Other Applications:
Quick Pick:
| Need | Choose |
|---|---|
| General architectural/indoor | ASTM A554 304 |
| Welded structures (thin wall) | ASTM A554 304L |
| Marine / coastal/outdoor | ASTM A554 316 |
| Marine welded structures | ASTM A554 316L |
Every ASTM A554 square tube we supply is backed by comprehensive quality control.
| Test | Purpose |
|---|---|
| Chemical analysis | Verify composition per ASTM A240 |
| Tensile test | Confirm yield, tensile, elongation |
| Flattening test | Assess ductility and weld quality |
| Reverse flattening test | Check weld soundness |
| Hydrostatic test | (Upon request – not typically required for mechanical tubing) |
| Eddy current / Ultrasonic NDT | Detect surface and weld defects |
| Dimensional inspection | Verify size, wall thickness, straightness, twist |
| Visual inspection | Check surface finish and weld appearance |
EN 10204 Type 3.1 – Mill test certificate (standard)
EN 10204 Type 3.2 – Third-party verified (available on request)
Full traceability – Heat number traceable to the mill
| Finish | Description | Application |
|---|---|---|
| Mill finish | As-welded, oxide present | Economy, will be painted/coated |
| Pickled | Acid cleaned, scale removed | Industrial, food equipment |
| Brushed (satin) | 180–240 grit, fine grain | Architectural, handrails |
| Polished | #4 polish, medium shine | Furniture, decorative |
| Mirror finish | #8 polish, highly reflective | High-end architectural showpieces |
| Advantage | Detail |
|---|---|
| Stock availability | Common sizes ready to ship |
| Custom cutting | Cut to exact lengths |
| Surface finishing | Brushing, polishing in-house |
| Fabrication services | Drilling, welding, and bending are available |
| Global shipping | Door-to-door delivery |
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