Orientation
Put the long side in the plane of bending. A 100 × 50 × 3 mm tube is about three times stiffer on edge than flat.
Structural rectangular hollow section
6061 Aluminium Rectangular Tube
6061 aluminium rectangular tube is an extruded, heat-treated hollow section that gives high bending stiffness about its deep axis at about a third of the weight of steel. In T6 it combines good strength, weldability, machinability and corrosion resistance, which makes it the standard rectangular tube for trailer and truck frames, machine bases, platforms, marine structures and solar mounts. Metline supplies 6061 rectangular tube in T6 and T6511, cut to length, worldwide.
- Alloy
- 6061 (Al-Mg-Si-Cu)
- Tempers
- T6, T6511, T4, O
- Process
- Extruded, drawn
- Standards
- ASTM B221 · AMS-QQ-A-200/8 · EN 755
Why use 6061 rectangular tube?
A rectangular tube places most of its material in the two wide flanges, far from the bending axis, so it resists bending much better about its depth than a square tube of the same weight. Oriented correctly, it is one of the most efficient beam shapes available in aluminium.
6061 is the most widely used heat-treatable structural aluminium alloy. Extruded rectangular tube is solution heat-treated, quenched and artificially aged to T6, or stretched before ageing to T6511 so it stays straight when machined. Compared with 6063 rectangular tube, which is typically used for architectural framing, 6061 offers roughly 25 – 40 % higher strength and better machinability, so it is chosen when the section carries real structural load.
Because the shape is closed, rectangular tube also performs well in torsion, resists local buckling better than open channels of the same depth, and has clean flat faces for bolting, welding brackets or mounting equipment. Common uses range from trailer chassis rails and cross-members to conveyor frames, gantries, boat T-tops and photovoltaic mounting rails.
6061 chemical composition (wt %)
Registered Aluminum Association limits, used by ASTM B221 and by EN 573-3 for EN AW-6061.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | 0.40 | 0.80 | Forms Mg2Si with magnesium, the strengthening phase |
| Iron (Fe) | — | 0.70 | Impurity; held low for ductility |
| Copper (Cu) | 0.15 | 0.40 | Adds strength after ageing |
| Manganese (Mn) | — | 0.15 | Grain control |
| Magnesium (Mg) | 0.80 | 1.20 | Main strengthening element with Si |
| Chromium (Cr) | 0.04 | 0.35 | Restrains grain growth; helps stress-corrosion resistance |
| Zinc (Zn) | — | 0.25 | Impurity |
| Titanium (Ti) | — | 0.15 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
Mechanical properties of 6061 rectangular tube
Use specified minimums for design. Typical values show what material usually achieves and are higher.
| Temper / product | Basis | Tensile strength | Yield strength | Elongation |
|---|---|---|---|---|
| T6 / T6511 extruded, wall ≤ 6.3 mm | Specified minimum (ASTM B221) | 260 MPa / 38 ksi | 240 MPa / 35 ksi | 8 % |
| T6 / T6511 extruded, wall > 6.3 mm | Specified minimum (ASTM B221) | 260 MPa / 38 ksi | 240 MPa / 35 ksi | 10 % |
| T6 drawn tube | Specified minimum (ASTM B210) | 290 MPa / 42 ksi | 241 MPa / 35 ksi | 8 – 12 % |
| T6 | Typical | 310 MPa / 45 ksi | 276 MPa / 40 ksi | 12 % |
| T4 | Typical | 240 MPa / 35 ksi | 145 MPa / 21 ksi | 22 % |
| As welded (heat-affected zone) | Design value commonly used | About 165 MPa / 24 ksi | About 103 – 110 MPa | — |
Physical properties (T6, typical)
- Density
- 2.70 g/cm³
- Modulus of elasticity
- 68.9 GPa (about one-third of steel)
- Shear strength
- 207 MPa
- Fatigue strength (5×10⁸ cycles)
- 96.5 MPa
- Thermal conductivity
- 167 W/m·K
- Thermal expansion (20 – 100 °C)
- 23.6 µm/m·°C
Sizes, weights and section properties
Section properties are calculated for sharp corners (real extrusions have small radii, so values are slightly lower). Ix and Zx are about the strong (depth) axis; Iy and Zy about the weak axis. Use the extruder's published values or the Aluminum Design Manual for final design.
| Depth × width (mm) | Wall (mm) | kg/m | Ix (cm⁴) | Zx (cm³) | Iy (cm⁴) | Zy (cm³) |
|---|---|---|---|---|---|---|
| 40 × 20 | 2 | 0.60 | 4.4 | 2.2 | 1.4 | 1.4 |
| 50 × 25 | 2 | 0.77 | 9.0 | 3.6 | 3.0 | 2.4 |
| 50 × 25 | 3 | 1.12 | 12.6 | 5.0 | 4.0 | 3.2 |
| 60 × 30 | 3 | 1.36 | 22.5 | 7.5 | 7.3 | 4.9 |
| 76.2 × 25.4 | 3.18 | 1.64 | 39.6 | 10.4 | 6.4 | 5.0 |
| 80 × 40 | 3 | 1.85 | 55.9 | 14.0 | 18.4 | 9.2 |
| 100 × 50 | 3 | 2.33 | 112.1 | 22.4 | 37.4 | 15.0 |
| 101.6 × 50.8 | 3.18 | 2.51 | 124.1 | 24.4 | 41.3 | 16.3 |
| 100 × 50 | 5 | 3.78 | 173.7 | 34.7 | 56.2 | 22.5 |
| 101.6 × 50.8 | 6.35 | 4.79 | 220.9 | 43.5 | 70.0 | 27.6 |
| 120 × 60 | 4 | 3.72 | 255.2 | 42.5 | 84.8 | 28.3 |
| 150 × 50 | 5 | 5.13 | 491.6 | 65.5 | 81.6 | 32.6 |
| 152.4 × 101.6 | 6.35 | 8.27 | 977.1 | 128.2 | 514.0 | 101.2 |
Supply range
- Sizes
- From small sections around 20 × 10 mm to large structural tube over 200 mm deep
- Walls
- Thin walls for frames to heavy walls for load-bearing members
- Corners
- Square or radiused corners, depending on the die
- Length
- Mill lengths (commonly 6 m or 20/24 ft) or cut to size
- Tolerances
- ANSI H35.2 for ASTM orders; EN 755-9 for EN orders
- Finish
- Mill, anodised, powder coated or brushed
Design and fabrication tips
Deflection
With a modulus about one-third of steel, aluminium sections must be deeper or thicker for the same stiffness; check deflection, not just strength.
Welding
MIG or TIG with ER4043 or ER5356. Weld zones fall to about 165 MPa tensile; place welds in low-stress areas or design to welded allowables.
Machining
T6511 stays straight when slotted or pocketed. Carbide tools, high speed, flood coolant.
Bending
T6 rectangular tube bends to large radii only; for tight bends, form in O or T4 and re-age.
Corrosion
Good atmospheric resistance; anodise or paint for marine and coastal exposure, and isolate from steel fasteners.
Standards and equivalents
| System | Designation | Specification |
|---|---|---|
| ASTM | 6061-T6 / T6511 | B221 (extruded), B429 (structural pipe and tube), B210 (drawn), B483 |
| SAE AMS | 6061 extrusions | AMS-QQ-A-200/8 |
| UNS | A96061 | — |
| European (EN) | EN AW-6061 (AlMg1SiCu) | EN 755-2 (properties), EN 755-9 (profile tolerances) |
| German Werkstoff | 3.3211 | — |
| Japan (JIS) | A6061 | JIS H4100 (shapes), JIS H4080 (tube) |
Structural design of aluminium members is covered by the Aluminum Design Manual in North America and Eurocode 9 (EN 1999) in Europe.
Where 6061 rectangular tube is used
- Transport: trailer chassis rails and cross-members, truck bodies, ramps and bus frames
- Machinery: conveyor and machine frames, gantries, automation bases and guards
- Marine: T-tops, towers, gangways and dock structures (anodised or painted)
- Construction and access: platforms, stair stringers, scaffolding and ladders
- Energy: solar mounting rails and frames
- Aerospace ground support and defence: equipment frames and shelters
6061 vs 6063 rectangular tube
| Factor | 6063-T6 | 6061-T6 |
|---|---|---|
| Typical tensile strength | 241 MPa | 310 MPa |
| Typical yield strength | 214 MPa | 276 MPa |
| Surface finish and anodising | Excellent | Good |
| Machinability | Fair | Good |
| Corner sharpness | Sharper corners possible | Usually small radii |
| Choose it for | Architectural, decorative | Structural, load-bearing |
More detail: 6061 vs 6063.
How to order 6061 rectangular tube
- SpecifyDepth × width × wall (metric or imperial), corner type, temper (T6 or T6511), standard, length and quantity.
- QuoteWe confirm availability or die, tolerances, finish and delivery terms (EXW, FOB, CIF or DAP).
- ProcessCutting to length, drilling or machining to drawing on request.
- ShipBundled, wrapped and crated with an EN 10204 3.1 mill certificate.
References and standards
- ASTM B221 – Extruded Bars, Rods, Wire, Profiles, and Tubes
- SAE AMS-QQ-A-200/8 – Aluminum Alloy 6061, Bar, Rod, Shapes, Tube and Wire, Extruded
- EN 755-2 and EN 755-9 – Extruded profiles: mechanical properties and tolerances
- The Aluminum Association – Aluminum Design Manual
- EN 1999 (Eurocode 9) – Design of aluminium structures
6061 aluminium (aluminum) rectangular tube: frequently asked questions
What is the difference between 6061-T6 and T6511 rectangular tube?
Both are solution treated and artificially aged to the same strength. T6511 is also stretched to relieve quench stresses, with minor straightening allowed, so it stays straight when machined.
How strong is 6061-T6 rectangular tube?
Specified minimums for extruded tube under ASTM B221 are 260 MPa (38 ksi) tensile and 240 MPa (35 ksi) yield. Typical values are about 310 MPa tensile and 276 MPa yield.
Can 6061 rectangular tube be welded?
Yes, by MIG or TIG with ER4043 or ER5356. The heat-affected zone falls to about 165 MPa tensile, so welded frames are designed to reduced allowables or re-heat-treated.
How much does 6061 rectangular tube weigh?
Mass per metre is (2 × (depth + width) − 4 × wall) × wall × 2.70 g/cm³. A 100 × 50 × 3 mm tube weighs about 2.33 kg/m; a 4 × 2 × 1/4 in tube about 4.79 kg/m (3.22 lb/ft).
Is 6061 or 6063 better for rectangular tube?
6061 for structural and load-bearing uses; 6063 for architectural framing where finish matters more than strength.
Do you supply 6061 rectangular tube internationally?
Yes. Metline ships 6061 tube worldwide from Mumbai with mill certificates and export packing.
Need 6061 rectangular tube?
Send sizes, temper, lengths and quantity. We will reply with availability, certification and a delivered price.
