T6 / T651
Peak strength. T651 rolled or cold-finished bar is stretched after quenching to reduce residual stress, so parts move less during machining.
Cold-finished and extruded aerospace bar
6061 Aerospace Aluminium Bar & Rod
6061 aerospace bar and rod is cold-finished or extruded 6061 certified to aerospace specifications such as AMS 4117 (T6/T651 cold-finished) and AMS 4150 (T6 extruded). It is the everyday machining stock for aircraft fittings, bushings, spacers, pins and hardware where good strength, corrosion resistance and weldability matter more than the peak strength of 2024 or 7075. Metline supplies round, square, flat and hex 6061 bar cut to length, worldwide.
- Alloy
- 6061 (Al-Mg-Si-Cu)
- Tempers
- O, T4, T451, T6, T651, T6511
- Shapes
- Round, square, flat, hex
- Specs
- AMS 4117 · AMS 4150 · ASTM B211
What is 6061 aerospace bar?
6061 bar and rod comes in two production routes. Cold-finished bar is extruded or rolled and then drawn to size, giving tight tolerances and a smooth surface for automatic lathes. Extruded bar comes straight from the press, usually in the stretched T6511 temper, and is the economical choice for larger sizes and for flat and special shapes.
Either route becomes aerospace material when it is made, tested, marked and certified to an aerospace specification, with the lot traceable to its cast. The chemistry and strength levels are those of normal 6061; what changes is the control and the paperwork. For a machined flight part, the specification on the drawing decides which bar can be used, so start every enquiry with it.
Aerospace specifications for 6061 bar and rod
| Specification | Product | Temper |
|---|---|---|
| SAE AMS 4115 | Rolled or cold-finished bar, rod and wire | O |
| SAE AMS 4116 | Rolled or cold-finished bar, rod and wire | T4 |
| SAE AMS 4117 | Rolled or cold-finished bar, rod, wire and flash-welded rings | T6, T651 |
| SAE AMS 4160 / 4161 | Extruded bar, rod, profiles and tube | O / T4 |
| SAE AMS 4150 | Extruded bar, rod, wire, profiles and tube | T6 |
| SAE AMS 4173 | Extruded bar, rod and profiles, stress-relieved by stretching | T6510, T6511 |
| AMS-QQ-A-225/8 | Former federal specification for 6061 rolled and cold-finished bar and rod | O, T4, T451, T6, T651 |
| AMS-QQ-A-200/8 | Former federal specification for 6061 extruded bar, rod and shapes | O, T4, T6, T6511 |
| ASTM B211 / B221 | Commercial cold-finished and extruded bar | All standard tempers |
The QQ-A documents survive as AMS-QQ-A specifications and still appear on many drawings. Quote the revision letter on your order so the certificate can state compliance with the correct edition.
6061 chemical composition (wt %)
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | 0.40 | 0.80 | Forms the strengthening Mg2Si phase with magnesium |
| Iron (Fe) | — | 0.70 | Impurity; held low for toughness and surface quality |
| Copper (Cu) | 0.15 | 0.40 | Adds strength; a small penalty in corrosion resistance |
| Manganese (Mn) | — | 0.15 | Grain structure control |
| Magnesium (Mg) | 0.80 | 1.20 | Main strengthening element with silicon |
| Chromium (Cr) | 0.04 | 0.35 | Limits recrystallisation, improves stress-corrosion resistance |
| Zinc (Zn) | — | 0.25 | Impurity |
| Titanium (Ti) | — | 0.15 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 95.8 – 98.6 % |
Mechanical properties of 6061 bar by temper
Minimum values below summarise ASTM B211 (cold-finished) and B221 (extruded) and the matching AMS documents. Typical values are for comparison only; design to the minimums.
| Temper and product | Tensile strength | Yield strength (0.2 %) | Elongation (min) |
|---|---|---|---|
| O, cold-finished (max) | ≤ 150 MPa / 22 ksi | — | 16 – 18 % |
| T4 / T451, cold-finished (min) | 205 MPa / 30 ksi | 110 MPa / 16 ksi | 18 % |
| T6 / T651, cold-finished (min) | 290 MPa / 42 ksi | 240 MPa / 35 ksi | 10 % |
| T4, extruded (min) | 180 MPa / 26 ksi | 110 MPa / 16 ksi | 16 % |
| T6 / T6511, extruded (min) | 260 MPa / 38 ksi | 240 MPa / 35 ksi | 8 – 10 % |
| T6, typical | 310 MPa / 45 ksi | 276 MPa / 40 ksi | 12 – 17 % |
Typical hardness of 6061-T6 is about 95 HB (roughly 60 HRB). Figures sometimes quoted for 6061-T451 of 470 MPa tensile are not correct; T451 has the same strength as T4.
Physical properties of 6061 (T6)
- Density
- 2.70 g/cm³ (0.0975 lb/in³)
- Modulus of elasticity
- 68.9 GPa (10,000 ksi)
- Thermal conductivity
- 167 W/m·K
- Electrical conductivity
- About 43 % IACS
- Coefficient of thermal expansion
- 23.6 µm/m·°C (20 – 100 °C)
- Melting range
- 582 – 652 °C
Choosing a 6061 bar temper
T6511
Extruded, stretched and straightened. The standard temper for extruded round, flat and hex bar used for machined parts.
T4 / T451
Lower strength, better ductility. Used for parts that are headed, swaged or bent and then aged to T6.
O
Annealed for heavy cold work such as upsetting, spinning or deep forming, followed by full heat treatment.
6061 aerospace bar sizes and weights
Supply range
- Round bar
- Diameter about 4 – 300 mm (0.125 – 12 in)
- Square bar
- About 6 – 150 mm across
- Flat bar
- Thickness 3 – 70 mm, width 10 – 300 mm
- Hex bar
- About 6 – 75 mm across flats
- Lengths
- Mill lengths 3 – 6 m (12 ft is common in imperial sizes); cut pieces to order
- Finish
- Cold-finished bright, extruded mill finish, or precision ground on request
Round bar weight in kg per metre = 0.002121 × d² (d in mm). Use the bar weight calculator for squares, flats and hexagons.
| Diameter (mm) | kg per metre | kg per 3 m length | Nearest inch size |
|---|---|---|---|
| 6 | 0.076 | 0.23 | 0.24 in |
| 10 | 0.212 | 0.64 | 0.39 in |
| 12.7 | 0.342 | 1.03 | 0.50 in |
| 16 | 0.543 | 1.63 | 0.63 in |
| 20 | 0.848 | 2.54 | 0.79 in |
| 25.4 | 1.368 | 4.10 | 1.00 in |
| 30 | 1.909 | 5.73 | 1.18 in |
| 38.1 | 3.078 | 9.23 | 1.50 in |
| 50.8 | 5.472 | 16.42 | 2.00 in |
| 63.5 | 8.551 | 25.65 | 2.50 in |
| 76.2 | 12.313 | 36.94 | 3.00 in |
| 101.6 | 21.890 | 65.67 | 4.00 in |
| 127 | 34.203 | 102.61 | 5.00 in |
| 152.4 | 49.252 | 147.76 | 6.00 in |
| 203.2 | 87.559 | 262.68 | 8.00 in |
Machining, joining and finishing 6061 bar
6061-T6 is the reference "easy" aluminium for CNC work. It cuts with short chips in T6, gives a good surface finish and holds threads well. It is a little gummier than 2011 or 7075, so sharp polished carbide tools with high positive rake and plenty of coolant help, especially on deep drilling and tapping. Avoid machining in O or T4 condition when you can: the softer material smears and builds up on the tool.
For welded assemblies use 4043 or 5356 filler and expect the heat-affected zone to lose part of the T6 strength. For corrosion protection and wear, 6061 bar takes Type II and hard Type III anodising evenly, and accepts chemical conversion coatings for primer adhesion.
Aerospace uses of 6061 bar and rod
- Fittings and brackets for systems, interiors and secondary structure
- Bushings, spacers and sleeves turned from round bar
- Hydraulic and pneumatic fittings, manifolds and valve bodies machined from round and square bar
- Fasteners, pins and shafts for lightly loaded mechanisms
- Ground-support equipment and tooling: jigs, fixtures, handles and adaptors
- Satellite and UAV hardware: mounts, standoffs, hinges and frames
Where a part needs much higher strength, 2024-T351 or 7075-T651 bar is used instead; where weldability and corrosion resistance govern, 6061 is usually the better choice.
How to order 6061 aerospace bar
- SpecifyAlloy and temper, shape and size, length or cut pieces, quantity and the governing specification with its revision (for example AMS 4117, AMS 4150, AMS 4173 or ASTM B211).
- ConfirmWe confirm the specification can be met, the tolerance class, any extra tests and the delivery terms (EXW, FOB, CIF or DAP).
- InspectMaterial is checked for dimensions, surface condition and identification; tests named on the order are carried out or arranged with a third party.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing chemistry and mechanical results, traceable to the cast or lot number.
- Pack and shipExport packing in sealed, moisture-protected wooden cases or on pallets, shipped by sea or air to your port or door.
References and standards
- SAE AMS 4117 – Aluminum Alloy, Rolled or Cold Finished Bars, Rods, and Wire, 6061-T6 / T651
- SAE AMS 4150 – Aluminum Alloy Extrusions, 6061-T6
- ASTM B211/B211M – Standard Specification for Aluminum and Aluminum-Alloy Rolled or Cold-Finished Bar, Rod, and Wire
- ASTM B221 – Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
6061 aerospace aluminium (aluminum) bar: frequently asked questions
Which specification covers 6061-T6 aerospace round bar?
AMS 4117 covers rolled or cold-finished 6061-T6 and T651 bar and rod. Extruded bar is covered by AMS 4150 (T6) and AMS 4173 (T6510/T6511). Older drawings may cite AMS-QQ-A-225/8 or AMS-QQ-A-200/8.
What is the difference between T651 and T6511 bar?
Both are stretched after quenching to reduce stress. T651 applies to rolled or cold-finished bar; T6511 applies to extruded bar and adds minor straightening after stretching.
Is cold-finished or extruded bar better for machining?
Cold-finished bar has tighter tolerances and a better surface, ideal for automatic lathes and small diameters. Extruded T6511 bar is more economical in large sizes and in flat and hex shapes.
How strong is 6061-T6 bar?
Cold-finished T6 bar has minimums of 290 MPa tensile and 240 MPa yield; typical values are about 310 MPa and 276 MPa. Extruded T6 bar has a slightly lower tensile minimum of 260 MPa.
Can 6061 bar replace 2024 or 7075 in aircraft parts?
Only if the stress analysis allows it, because 6061 is considerably weaker. It is chosen where corrosion resistance, weldability and cost outweigh strength.
Do you cut 6061 bar to length for export?
Yes. Metline cuts bar to length, marks each piece with lot identification where required, and ships worldwide with an EN 10204 3.1 certificate.
Need 6061 bar to an aerospace specification?
Send the shape, size, temper, quantity and specification. Our team will reply with availability and a delivered price.
