6063-T4
Solution treated and naturally aged. Softer and more formable; used for parts that will be bent or stretch-formed and then aged.
Aerospace · Extruded flat and bar
6063 Aerospace Aluminium Flat Bar & Bar
6063 flat bar is extruded from the alloy with the best surface finish and extrudability in the 6xxx family, and is used in aircraft interiors, trim, electrical bonding strips and ground equipment where appearance and corrosion resistance matter more than high strength. Metline supplies 6063 flat, round, square and hex bar in T4, T5, T52 and T6, certified to AMS 4156, ASTM B221 or EN 755, to buyers worldwide.
- Alloy
- 6063 (Al-Mg-Si)
- Tempers
- O, T4, T5, T52, T6
- Flat bar
- 3 – 25 mm × 10 – 200 mm
- Standards
- AMS 4156 · ASTM B221 · EN 755
Where 6063 bar fits in aerospace work
6063 is a low-alloy Al-Mg-Si grade designed for extrusion. It flows through dies at high speed, gives sharp corners and smooth faces, and anodises to an even, bright finish. The trade-off is strength: 6063-T6 has about three-quarters of the strength of 6061-T6.
That balance decides where it is used in aircraft. Primary and secondary structure goes to 2xxx, 7xxx and 6061 alloys. 6063 flat bar earns its place in non-structural and lightly loaded parts: cabin trim strips, threshold and kick plates, light-fitting and placard frames, seat and galley trim, cable-tray supports, electrical bonding and earthing straps, heat-sink bars for avionics and countless items of ground support equipment. SAE recognises this role in AMS 4156, which describes 6063-T6 extrusions as generally used where a good surface finish or intricate, hollow shapes are needed.
Flat bar is the most common 6063 bar form because it is extruded directly to size with a clean, square edge and needs little or no machining. Round, square and hex bar are also produced, mostly for turned or milled parts where finish and anodising quality outweigh strength.
6063 chemical composition (wt %)
Registered Aluminum Association limits, also used by ASTM B221, AMS 4156 and EN 573-3 (EN AW-6063, AlMg0.7Si). Each lot is certified with its actual analysis.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | 0.20 | 0.60 | Forms Mg2Si with magnesium |
| Iron (Fe) | — | 0.35 | Kept low for bright finish and extrudability |
| Copper (Cu) | — | 0.10 | Low, protects corrosion resistance |
| Manganese (Mn) | — | 0.10 | Residual |
| Magnesium (Mg) | 0.45 | 0.90 | Main strengthening element with Si |
| Chromium (Cr) | — | 0.10 | Residual |
| Zinc (Zn) | — | 0.10 | Impurity |
| Titanium (Ti) | — | 0.10 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 97.5 – 99.4 % |
Mechanical properties of 6063 bar by temper
Specified minimums below are summarised from ASTM B221 and EN 755-2 for extruded bar; the exact values depend on thickness band and are printed on the certificate. Typical values are higher.
| Temper | Tensile strength (min) | Yield strength 0.2 % (min) | Elongation (min) | Typical hardness |
|---|---|---|---|---|
| O | ≤ 131 MPa (max) | — | 18 % | about 25 HB |
| T4 | 130 MPa | 65 – 69 MPa | 12 – 14 % | about 45 HB |
| T5 | 152 – 175 MPa | 110 – 130 MPa | 6 – 8 % | about 60 HB |
| T52 | 152 – 207 MPa (range) | 110 – 172 MPa (range) | 8 % | about 55 HB |
| T6 | 205 – 215 MPa | 170 – 172 MPa | 8 – 10 % | about 73 HB |
Typical 6063-T6 values are about 241 MPa tensile and 214 MPa yield with 12 % elongation. ASTM limits for T5 apply to thicknesses up to 12.7 mm; thicker T5 sections have slightly lower minimums.
Physical properties (T6)
- Density
- 2.69 – 2.70 g/cm³ (0.0975 lb/in³)
- Modulus of elasticity
- 68.9 GPa (10,000 ksi)
- Thermal conductivity
- about 200 W/m·K
- Electrical conductivity
- about 53 % IACS (T6), up to 58 % (T5 / O)
- Coefficient of thermal expansion
- 23.4 µm/m·°C (20 – 100 °C)
- Melting range
- 615 – 655 °C
Choosing a 6063 temper
6063-T5
Cooled from the extrusion press and artificially aged. The most economical temper with moderate strength and excellent finish.
6063-T52
Press-quenched and aged to a controlled, lower range. Chosen when consistent, moderate hardness is needed for bending or anodised trim.
6063-T6
Fully solution treated and aged, the highest standard strength and the temper covered by AMS 4156.
6063-O
Annealed for maximum ductility in severe forming.
6063-T66
A higher-strength European variant (EN 755-2) with controlled chemistry; useful when T6 is just short of the strength target.
6063 bar standards and designations
Aerospace orders usually cite AMS 4156 for 6063-T6 extrusions (covering bar, rod, profiles and tube; recent revisions limit size to 25.4 mm least thickness). Commercial and ground-equipment orders use ASTM B221 or EN 755. Older drawings may quote QQ-A-200/9, the cancelled federal 6063 extrusion standard, or the British designation H9.
| System | Designation / standard | Scope |
|---|---|---|
| SAE AMS | AMS 4156 | 6063-T6 extrusions |
| ASTM / ASME | ASTM B221 (SB-221) | Extruded bar, rod, wire, profiles and tube |
| US Federal (legacy) | QQ-A-200/9 | 6063 extrusions; cancelled for new design |
| UNS | A96063 | — |
| European | EN AW-6063 (AlMg0.7Si); EN 755-1/-2/-5 | Extruded flat bar (EN 755-5 tolerances) |
| British (legacy) | H9 (BS 1474) | Superseded by EN 755 |
| German Werkstoff | 3.3206 | — |
| Japan | A6063BE | JIS H4040 |
6063 flat bar sizes and weights
Supply range
- Flat bar
- Thickness about 3 – 25 mm, width 10 – 200 mm; wider sections by die
- Round bar
- About 6 – 150 mm diameter
- Square and hex
- Common sizes from 6 mm to 100 mm
- Length
- 4000 mm or 6000 mm, or cut to length
- Edges
- Square or radiused edges as extruded
- Finish
- Mill finish, anodised or film-protected on request
Popular metric flats include 3 × 10 up to 3 × 50 mm and 4 × 20 up to 4 × 50 mm; imperial flats are available by enquiry.
Flat bar weight per metre is thickness × width (mm) × 0.0027 kg. Reference weights:
| Size (mm) | kg per metre | kg per 6 m length |
|---|---|---|
| 3 × 10 | 0.081 | 0.49 |
| 3 × 20 | 0.162 | 0.97 |
| 3 × 25 | 0.203 | 1.22 |
| 3 × 40 | 0.324 | 1.94 |
| 3 × 50 | 0.405 | 2.43 |
| 4 × 25 | 0.270 | 1.62 |
| 4 × 40 | 0.432 | 2.59 |
| 5 × 25 | 0.338 | 2.03 |
| 5 × 50 | 0.675 | 4.05 |
| 6 × 30 | 0.486 | 2.92 |
| 6 × 50 | 0.810 | 4.86 |
| 8 × 40 | 0.864 | 5.18 |
| 10 × 50 | 1.350 | 8.10 |
| 10 × 100 | 2.700 | 16.20 |
| 12 × 60 | 1.944 | 11.66 |
| 20 × 100 | 5.400 | 32.40 |
Tolerances, straightness and inspection
Cross-section tolerances follow ANSI H35.2 (via ASTM B221 and AMS 4156) or EN 755-5 for flat bar. Straightness, twist and edge squareness are checked on every bundle; flat bar for visible trim is also inspected for die lines, pick-up and handling marks.
- Dimensions checked for thickness, width, corner radius and length
- Surface inspected for streaks or marks that would show after anodising
- Mechanical and hardness tests per lot, with Webster or Brinell hardness on request
- Certification to EN 10204 3.1, traceable to the cast and extrusion lot
Machining, welding, forming and finishing
Machining
Fair: in T5 and T6 it machines cleanly with sharp tools, but softer tempers form long chips. For heavily machined parts, 6061 or 6082 is easier.
Welding
Very good by TIG and MIG with ER4043 or ER5356. The heat-affected zone softens towards T4 strength.
Forming
Bends well in T4 and T52; T6 needs larger radii. Age after forming to raise strength.
Anodising
The main reason to choose 6063: even, bright clear and coloured finishes, and good hard anodising.
Corrosion
Very good in atmospheric service; anodise or prime for marine-exposed GSE.
Electrical use
Conductivity is higher than 6061, so 6063 flats serve as bonding straps and small busbars.
Typical aerospace uses of 6063 flat bar
- Cabin interiors: trim strips, edge guards, kick plates, light and sign frames
- Electrical: bonding straps, earthing bars and small busbars in equipment racks
- Avionics cooling: heat-spreader bars and mounting rails where thermal conductivity helps
- Ground support equipment: handrails, step treads, frames and covers that stay outdoors
- Hangar and maintenance tooling: fixtures, guides and storage racks
Old trade descriptions sometimes list 6063 for wing ribs or landing-gear parts. These are structural, fatigue-critical components normally made from 2xxx or 7xxx alloys, so treat such claims with caution and follow the drawing.
6063 flat bar compared with 6061 and 6082
| Property | 6063-T6 | 6061-T6 | 6082-T6 |
|---|---|---|---|
| Typical tensile strength | 241 MPa | 310 MPa | 310 – 340 MPa |
| Typical yield strength | 214 MPa | 276 MPa | 260 – 300 MPa |
| Surface finish as extruded | Excellent | Good | Good |
| Anodising quality | Excellent | Very good | Good |
| Machinability | Fair | Very good | Very good |
| Electrical conductivity | about 53 % IACS | about 43 % IACS | about 40 – 45 % IACS |
Choose 6061 or 6082 when the bar carries load or will be heavily machined; stay with 6063 when finish, conductivity or forming matter most.
How to order 6063 aerospace flat bar
- SpecifyAlloy and temper, shape and size, length and finish, quantity and the governing specification with its revision (AMS 4156, ASTM B221 or EN 755).
- 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, straightness and surface condition; 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 4156 – Aluminum Alloy Extrusions, 6063-T6, Solution and Precipitation Heat Treated
- ASTM B221 – Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes
- EN 755-2 – Aluminium and aluminium alloys: extruded rod/bar, tube and profiles, mechanical properties
- EN 755-5 – Extruded rectangular bars: tolerances on dimensions and form
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits (Teal Sheets)
- ASM Handbook, Vol. 2 – Properties and Selection: Nonferrous Alloys and Special-Purpose Materials
6063 aerospace aluminium (aluminum) flat bar: FAQs
Is 6063 strong enough for aircraft structure?
Not for primary structure. 6063-T6 has a typical tensile strength of about 241 MPa, so it is used for trim, interiors, electrical straps and ground equipment. Load-bearing parts use 6061, 2024 or 7075.
Which aerospace specification covers 6063?
AMS 4156 covers 6063-T6 extrusions, including bar and flat bar. Commercial orders commonly use ASTM B221 or EN 755-2.
What is the difference between 6063-T5 and T6?
T5 is cooled from the press and aged; T6 is fully solution treated (or press-quenched to equal effect) and aged. T6 is stronger, with minimum tensile around 205 MPa against about 152 MPa for T5.
Why choose 6063 over 6061 flat bar?
For a better surface finish, more even anodising, sharper extruded detail and higher electrical conductivity. Choose 6061 if strength or machining matters more.
How much does a 6063 flat bar weigh?
Multiply thickness by width in millimetres by 0.0027 to get kg per metre. A 6 × 50 mm flat weighs about 0.81 kg per metre.
Can you supply 6063 flat bar anodised or cut to length?
Yes. Metline supplies 6063 flat bar mill finish, anodised or film-protected, in full lengths or cut pieces, with an EN 10204 3.1 certificate, worldwide.
Need 6063 flat bar for an aircraft or GSE part?
Send the size, temper, specification, finish and quantity. We will reply with availability, certification and a delivered price.
