6061-T6
Solution-treated and artificially aged. The standard temper for extruded and rolled flat bar used as supplied or lightly machined.
Structural Al-Mg-Si flat bar
6061 Aluminium Flat Bar
6061 flat bar is the general-purpose structural rectangle in aluminium: strong in T6 temper, weldable, corrosion resistant and easy to machine. It is used for frames, brackets, base plates, rails, busbars and machined parts across engineering, transport and construction. Metline supplies 6061 flat bar in T6, T6511, T651 and T4, extruded or cold-finished, cut to length and shipped worldwide.
- Alloy
- 6061 (Al-Mg-Si-Cu)
- Tempers
- T6, T6511, T651, T4, O
- Typical tensile
- About 310 MPa (T6)
- Standards
- ASTM B221 · B211 · EN 755
Why 6061 is the default choice for aluminium flat bar
If a drawing simply says "aluminium flat bar" and the part carries load, 6061-T6 is usually what the designer had in mind. It combines useful strength with weldability, corrosion resistance and good machining in one alloy.
6061 is a heat-treatable aluminium-magnesium-silicon alloy with a small copper and chromium addition. Solution heat treatment followed by artificial ageing produces fine Mg2Si precipitates, giving T6 a typical yield strength around 275 MPa, about twice that of 6063-T5 and well above any common non-heat-treatable alloy. It resists atmospheric and fresh-water corrosion well, and it takes clear and coloured anodising.
Flat bar is made in two ways. Extruded bar (T6 or T6511) is the most common: the profile is pressed through a flat die, quenched at the press or in a furnace, stretched and aged. It covers the widest size range at the lowest cost. Cold-finished or rolled bar (T6 or T651) is drawn or rolled to closer tolerances and sharper corners, and is chosen when the bar is used with little or no machining. Wide, thick flats can also be sawn from 6061-T651 plate.
6061 chemical composition (wt %)
| Element | Minimum | Maximum |
|---|---|---|
| Silicon (Si) | 0.40 | 0.8 |
| Iron (Fe) | — | 0.7 |
| Copper (Cu) | 0.15 | 0.40 |
| Manganese (Mn) | — | 0.15 |
| Magnesium (Mg) | 0.8 | 1.2 |
| Chromium (Cr) | 0.04 | 0.35 |
| Zinc (Zn) | — | 0.25 |
| Titanium (Ti) | — | 0.15 |
| Others, each / total | — | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
Aluminum Association registered limits, used in ASTM B221, ASTM B211 and EN 573-3 (EN AW-6061 / EN AW-AlMg1SiCu).
6061 flat bar properties by temper
| Temper | Tensile (typical) | Yield (typical) | Elongation (typical) | Specified minimum (tensile / yield) |
|---|---|---|---|---|
| O | 125 MPa | 55 MPa | 25 % | Maximum limits apply |
| T4 / T4511 | 240 MPa | 145 MPa | 22 % | 180 / 110 MPa (extruded, ASTM B221) |
| T6 / T6511 (extruded) | 310 MPa | 275 MPa | 12 % | 260 / 240 MPa (ASTM B221) |
| T6 / T651 (cold-finished) | 310 MPa | 275 MPa | 12 – 15 % | 290 / 240 MPa (ASTM B211) |
Typical values from Aluminum Association and ASM data. Minimums are as listed in ASTM B221 and B211 for the common size range; elongation minimums vary with thickness, and EN 755-2 values differ slightly. The mill certificate governs for each lot.
Physical properties
- Density
- 2.70 g/cm³
- Melting range
- About 582 – 652 °C
- Modulus of elasticity
- 68.9 GPa
- Hardness (T6, typical)
- 95 HB
- Shear strength (T6, typical)
- 207 MPa
- Thermal conductivity (T6)
- 167 W/m·K
- Electrical conductivity (T6)
- About 43 % IACS
- Coefficient of thermal expansion
- 23.6 µm/m·°C (20 – 100 °C)
Which temper of 6061 flat bar to order
6061-T6511
Extruded, stretched for stress relief, aged, with minor straightening allowed. Stays flatter when slotted or machined on one face.
6061-T651
Stress-relieved by stretching; used for cold-finished bar and for flats sawn from plate. Best for heavy machining.
6061-T4 / O
Softer tempers for bending and forming, after which parts can be aged to T6-level strength.
For flats that will be machined on one side only, such as base plates or slotted rails, specify a stress-relieved temper (T6511 or T651). Unrelieved T6 bar can bow when metal is removed from one face, because quenching leaves compressive stress at the surface.
Standards and international equivalents
| System | Designation | Product standard |
|---|---|---|
| Aluminum Association / ASTM | 6061 | ASTM B221 (extruded), ASTM B211 (cold-finished) |
| UNS | A96061 | — |
| Aerospace (SAE AMS) | 6061-T6 / T6511 | AMS-QQ-A-200/8 (extruded), AMS-QQ-A-225/8 (cold-finished) |
| European (EN) | EN AW-6061 / EN AW-AlMg1SiCu | EN 755-1/-2/-5 (extruded), EN 754 (drawn), EN 573-3 |
| German Werkstoff | 3.3211 | DIN EN 755 |
| ISO | AlMg1SiCu | ISO 6362 |
| Japan (JIS) | A6061 | JIS H4040 |
| China (GB) | 6061 | GB/T 3191 |
| India (IS) | 65032 (nearest) | IS 733 |
In Europe, 6082-T6 is often stocked in place of 6061-T6 for structural flat bar. The two are interchangeable for most uses; 6082 is slightly stronger, 6061 slightly better for anodising and finish. We supply both.
6061 flat bar sizes and weight per metre
Supply range
- Thickness
- About 3 – 100 mm (thicker flats sawn from plate)
- Width
- About 10 – 400 mm, depending on thickness and production route
- Inch sizes
- 1/8 in to 4 in thick, 1/2 in to 12 in wide, on request
- Lengths
- Mill lengths, typically 3 m, 3.66 m (12 ft) or 6 m; cut pieces to order
- Finish
- Mill finish, or anodised on request
Weight per metre = thickness (mm) × width (mm) × 0.0027. Typical sizes:
| Thickness × width (mm) | kg per metre | kg per 3 m bar | kg per 3.66 m (12 ft) bar |
|---|---|---|---|
| 6 × 25 | 0.41 | 1.22 | 1.5 |
| 10 × 50 | 1.35 | 4.05 | 4.9 |
| 12 × 75 | 2.43 | 7.29 | 8.9 |
| 20 × 100 | 5.40 | 16.20 | 19.8 |
| 25 × 150 | 10.12 | 30.38 | 37.1 |
| 40 × 200 | 21.60 | 64.80 | 79.1 |
| 50 × 250 | 33.75 | 101.25 | 123.5 |
Tolerances and inspection
Extruded flat bar is supplied to the tolerances in ANSI H35.2 (ASTM B221) or EN 755-5, which cover thickness, width, corner radius, flatness, straightness and twist. Cold-finished bar to ASTM B211 or EN 754-5 holds closer limits. If a face must be flat to a tight figure without machining, say so at enquiry stage: we will propose cold-finished bar, a stress-relieved temper or a flat sawn from plate.
| Check | Method | Reported on |
|---|---|---|
| Chemistry | Spectrometer analysis of the cast | EN 10204 3.1 certificate |
| Tensile, yield, elongation | Per lot to ASTM B557 or EN ISO 6892-1 | EN 10204 3.1 certificate |
| Hardness or conductivity | Temper confirmation on request | Inspection report |
| Dimensions, flatness, twist | Callipers, micrometers, surface table | Inspection report |
| Surface | Visual check for die lines, scratches and corrosion | Packing list remarks |
Machining, welding, bending and finishing
Machining
Good in T6 and T651, with continuous chips that break better with chip-breaker inserts. Use sharp carbide tools, high speeds and coolant.
Welding
TIG and MIG with ER4043 (less crack-sensitive) or ER5356 (stronger, better colour match after anodising). The heat-affected zone falls to roughly T4-level strength, so size welds accordingly.
Bending
T6 flat bar bends best the easy way (across the thickness) over a radius of about 1.5 – 3 × thickness, depending on thickness. For tight bends, order T4 or anneal locally.
Finishing
Anodises well for wear and appearance; powder-coats and paints after conversion coating.
Where 6061 flat bar is used
- Structures and frames: brackets, gussets, braces, base plates and supports
- Transport: trailer and truck body parts, rail and bus fittings, marine hardware above the waterline
- Machinery: guards, rails, spacers, jig plates and machined components
- Electrical: busbars and earthing strips where strength matters as well as conductivity
- Construction: handrail posts, stair parts, balustrade fixings and architectural trim
- Fabrication and DIY: general workshop stock for welded and bolted assemblies
6061 flat bar compared with 6063, 6082 and 7075
| Property | 6063-T6 | 6061-T6 | 6082-T6 | 7075-T6 |
|---|---|---|---|---|
| Typical tensile strength | 240 MPa | 310 MPa | 340 MPa | 570 MPa |
| Typical yield strength | 215 MPa | 275 MPa | 310 MPa | 505 MPa |
| Weldability | Very good | Good | Good | Not for arc welding |
| Anodised appearance | Excellent | Good | Fair | Fair |
| Typical use | Trim, architectural | General structural | Structural (Europe) | Highly stressed parts |
Pick 6063 for visible trim where finish matters more than strength, 7075 for highly stressed machined parts that will not be welded, and 6061 for nearly everything in between. Our 6061 vs 6063 and 6061 vs 7075 articles go into more detail.
How to order 6061 flat bar
- SpecifyAlloy and temper (for example 6061-T6511), thickness, width, length, quantity and standard.
- QuoteWe confirm availability, route (extruded or cold-finished), tolerances and terms (EXW, FOB, CIF or DAP).
- CutBars supplied in mill lengths or saw-cut to size, marked with alloy, temper and lot number.
- DocumentEN 10204 3.1 mill test certificate with chemistry and tensile results.
- ShipBundled with interleaving to protect faces, wrapped and crated for export by sea or air.
References and standards
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes
- ASTM B211 – Aluminum and Aluminum-Alloy Rolled or Cold-Finished Bar, Rod and Wire
- EN 755-2 – Extruded rod/bar, tube and profiles: mechanical properties
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- ASM Handbook, Volume 2 – Properties of Wrought Aluminum Alloys
6061 aluminium flat bar: frequently asked questions
What is the difference between 6061-T6 and T6511 flat bar?
Both have the same strength. T6511 has been stretched to relieve quenching stress, so it moves less when machined on one face. T6 is fine when the bar is used as supplied.
Can 6061 aluminum flat bar be welded?
Yes. TIG and MIG with ER4043 or ER5356 filler work well. Expect the area next to the weld to lose some strength unless the part is heat-treated again.
Can 6061-T6 flat bar be bent?
Yes, over a generous radius, typically 1.5 – 3 × thickness for bends across the thickness. Tight bends crack; order T4 or anneal the bend area for those.
Is 6061 flat bar suitable for outdoor use?
Yes. It resists weathering well and is often used uncoated. Anodise or paint it for coastal or polluted environments, or where appearance must last.
How much does 6061 flat bar weigh?
Multiply thickness by width in millimetres and by 0.0027 to get kg per metre. A 10 × 50 mm bar weighs 1.35 kg/m.
Is 6061 or 6082 better for flat bar?
They are near equivalents. 6082 is slightly stronger and common in Europe; 6061 anodises a little better and is standard in North America and Asia.
Need 6061 flat bar?
Send size, temper, length, quantity and destination. We will confirm availability and quote a delivered price.
