6063 Aluminum
Also: AA6063, UNS A96063, AlMg0.7Si, 6063-T5, 6063-T6, 6063-T52, architectural aluminum, Al 6063
6063 is the architectural extrusion alloy: intricate thin-wall profiles, the best anodized finish of the common alloys, at 75% of 6061 strength. Values for T6.
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At a glance
| Density | 2.7 g/cm³ (0.0975 lb/in³) |
|---|---|
| Tensile strength | 241 MPa (35 ksi) |
| Yield strength | 214 MPa (31 ksi) |
| Hardness | 73 HB |
| Elongation | 12% |
| Modulus of elasticity | 68.9 GPa (10.0 Msi) |
| Thermal | Melts at 615-655 °C (1140-1210 °F); thermal conductivity ~200 W/m·K (T6), ~209 W/m·K (T5), the highest of the common structural alloys |
| Composition | Al, 0.45-0.9% Mg, 0.2-0.6% Si, up to 0.35% Fe, up to 0.1% Cu |
Typical values, T6 temper (solution treated and artificially aged). T5 (press-quenched and aged, the usual stock temper) is about 186 MPa (27 ksi) tensile and 145 MPa (21 ksi) yield. Confirm against the mill certificate and the purchase spec.
- MachinabilityFair
- Softer and gummier than 6061; T6 machines cleanly with sharp tooling and high speed, T5 smears on drilling and tapping. Fine for cutting extrusions to length and adding holes, a poor choice for parts machined from solid.
- WeldabilityExcellent
- Welds easily by TIG and MIG with 4043 or 5356 filler. As with 6061, the heat-affected zone falls toward annealed strength, which matters less because 6063 parts are rarely strength-critical.
- FormabilityGood
- T5 extrusions bend and tube-bend more easily than 6061-T6; T6 needs about 1.5-2x thickness inside radius. Extruded shapes bend best on a mandrel or rotary-draw bender with the profile supported.
- Corrosion resistanceExcellent
- Slightly better than 6061 because of its low copper; used bare or anodized outdoors for decades in architectural service. Isolate from steel fasteners in wet locations.
6063 is a lean magnesium-silicon (6xxx series) alloy formulated to extrude fast and fill intricate dies. It is the alloy behind window frames, curtain wall, heat sinks, lighting extrusions, railings, T-slot framing and most stock architectural shapes. Its lower alloy content also gives it a smoother surface off the die and a brighter, more uniform anodized finish than 6061, which is why anodized cosmetic parts are specified in 6063 when the shape allows.
It is heat-treatable but weaker than 6061: about 241 MPa (35 ksi) tensile in T6 and 186 MPa (27 ksi) in the T5 temper that most stock extrusions are sold in. T5 means the profile was quenched at the press and aged without a separate solution treatment; it is cheaper and adequate for frames, trim and enclosures. Specify T6 when the extrusion carries real load.
6063 is rarely stocked as sheet, plate or bar: it exists for extrusions and tube. It machines acceptably in T6 but is softer and gummier than 6061, and welds readily with 4043 or 5356 filler. Corrosion resistance is slightly better than 6061 because of its lower copper content.
Heat treatment
Precipitation hardening. T5 is produced at the extrusion press: the profile is quenched with air or water as it exits the die, then aged at about 175-205 °C (350-400 °F). T6 adds a separate solution treatment at about 520 °C (970 °F) and water quench before aging at about 175 °C (350 °F) for 8 hours, and is used where the higher strength is needed. T52 and T54 are T5 variants with straightening. Annealing (O) is about 415 °C (775 °F) with a slow cool.
Tempers and conditions
- T5 (press-quenched and aged, the usual stock temper)
- T52
- T6
- T4 (for bending, then age)
- O (annealed)
Stock forms
- Extruded angle, channel, tee, I-beam and Z
- Extruded round, square and rectangular tube
- Custom extruded profiles and heat sinks
- Pipe (Schedule 40 and 80)
- Drawn tube
- T-slot framing
Relative cost
Tier 2 of 5. The cheapest aluminum per pound in extruded form, at or a little below 6061 extrusions. Stock architectural shapes are commodity items; custom dies cost a few hundred to a few thousand dollars.
Typical applications
- Window, door and curtain wall frames
- Heat sinks and LED lighting extrusions
- Handrails, balustrades and architectural trim
- T-slot framing and machine guarding
- Furniture, signage and display extrusions
- Irrigation and low-pressure pipe
- Electrical bus and enclosure extrusions
Process compatibility
How 6063 takes each process, and what to specify. Each process links to its own guide and to the shops that do it.
| Process | Rating | Notes |
|---|---|---|
| Aluminum Extrusion | ExcellentExcellent | The reference extrusion alloy: fastest press speeds, thinnest walls and the most intricate profiles. Custom dies are cheap relative to any other process. |
| Anodizing | ExcellentExcellent | The best anodizing alloy of the common grades: bright, uniform Type II clear and dyed finishes; the standard for architectural anodize (AAMA 611). Can 6063 aluminum be anodized? |
| Powder Coating | ExcellentExcellent | The other architectural finish (AAMA 2604/2605); needs a chromate or chrome-free pretreatment for adhesion. |
| Welding | ExcellentExcellent | TIG or MIG with 4043 or 5356 filler; frames, railings and enclosures weld cleanly. Weld zone drops toward annealed strength. |
| Tube Bending | GoodGood | Extruded tube in T5 bends well on a rotary-draw bender with a mandrel; T6 needs larger radii. Bend before anodizing. |
| Laser Cutting | GoodGood | Tube lasers cut and notch 6063 profiles cleanly; flat-bed lasers rarely see it because it is not stocked as sheet. |
| CNC Machining | FairFair | Softer than 6061 and smears in T5; fine for cutting to length, drilling and pocketing extrusions, not for parts machined from solid. |
| Press Brake Forming | GoodGood | Extruded flat bar and T5 profiles bend at about 1x thickness; T6 at 1.5-2x. Support the profile so it does not collapse. |
| Chem Film (Chromate Conversion Coating) | GoodGood | MIL-DTL-5541 chromate for conductive enclosures and as a paint base; less common than anodize on 6063. |
| Heat Treating | GoodGood | Stock T5 can be re-solution-treated and aged to T6 by a heat treater when the higher strength is needed; expect some distortion on long thin profiles. |
| Hardcoat Anodizing | GoodGood | Type III builds well on 6063 and is used on heat-sink and slide extrusions; the coating is slightly softer than on 6061. |
| Sheet Metal Fabrication | PoorPoor | Not stocked as sheet or plate; a sheet metal part in 6063 means starting from a flat extrusion. Use 5052 or 6061 sheet instead. |
| Forging | PoorPoor | Not a forging alloy; forged parts are made in 6061, 2014 or 7075. |
Compare 6063
Design and sourcing tips
- Specify the temper: stock extrusions are T5 unless you say otherwise; call out "6063-T6" when the profile carries structural load or will be tapped.
- For anodized cosmetic parts that must match, keep every visible piece in 6063 from the same extruder lot; 6061 next to it looks slightly darker and greyer.
- Design the extrusion to do the work: put snap fits, screw bosses, slots and heat-sink fins in the profile and keep secondary machining to cut-off and holes.
- Wall thickness of 1.5-2 mm (0.06-0.08") extrudes reliably; below 1 mm needs an extruder that specializes in thin-wall profiles.
- If the part is mostly machined from solid, or needs 6061 strength, buy 6061 bar or plate instead; 6063 is not stocked in those forms.
- For architectural exposures call out the anodize class and thickness (AAMA 611 Class I, 18 um / 0.7 mil) or the powder coating spec (AAMA 2604 or 2605).
Frequently asked questions
- What is the difference between 6063 and 6061 aluminum?
- Both are heat-treatable magnesium-silicon alloys. 6063 has less alloy content, so it extrudes into finer and thinner shapes, anodizes brighter and more evenly, and conducts heat better, but it is about 25% weaker (241 vs 310 MPa tensile in T6) and softer to machine. 6061 is stocked in bar, plate and sheet as well as extrusions; 6063 is essentially an extrusion and tube alloy.
- What does 6063-T5 mean?
- T5 means the extrusion was cooled quickly at the press as it left the die and then artificially aged, without a separate solution heat treatment. It reaches about 186 MPa (27 ksi) tensile, compared with 241 MPa (35 ksi) for T6, and is the temper most stock shapes are sold in because it is cheaper and adequate for frames and trim.
- Is 6063 aluminum good for anodizing?
- It is the best of the common alloys. Its low iron, copper and silicon content give a clear, bright, uniform anodized surface, which is why architectural anodize and anodized consumer extrusions are almost always 6063. Colour matching across lots still depends on the extruder and anodizer keeping the same lot and process.
- Can 6063 aluminum be welded?
- Yes, readily, by TIG or MIG with 4043 or 5356 filler. As with 6061, the heat-affected zone loses strength toward the annealed value, but most 6063 frames and railings are designed with enough margin that this does not matter. Weld before anodizing.
Processes that commonly use it
Related materials
Where to verify these values
- ASTM B221 (extrusion mechanical property minimums by temper)
- ASTM B241 and B429
- Aluminum Association, Aluminum Standards and Data
- AAMA 611 and AAMA 2604/2605 (architectural finish specifications)
