Aluminum 6066 · temper
Aluminum 6066-O
Properties of the O condition, compared with the other 6066 tempers.
Softest condition for severe forming or machining of complex blanks before solution treating to T6.
What is 6066-O?
6066-O is 6066 in the O temper — softest condition for severe forming or machining of complex blanks before solution treating to T6. 6066-O has a yield strength of 83 MPa (12 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 89% of aluminum grades. Elongation at break is 18% and the elastic modulus is 69 GPa (10 Msi). 6066-O has a density of 2.72 g/cm³ (0.0983 lb/in³), heavier than 57% of aluminum grades. It melts at 563°C (1,045 °F).
Advantages
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- Ductile — tolerates forming and impact — 18%, better than 86% of aluminum grades
- Forms and bends easily — 75/100, better than 86% of aluminum grades
- High electrical conductivity — 43 % IACS, better than 83% of aluminum grades
Limitations
- Low strength — 83 MPa (12 ksi), worse than 89% of aluminum grades
6066-O properties
Typical room-temperature values for 6066-O — 14 properties are specific to this condition; the rest are grade-level values shared by every 6066 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
6066-O has a density of 2.72 g/cm³ (0.0983 lb/in³), heavier than 57% of aluminum grades. It melts at 563°C (1,045 °F).
Mechanical11
6066-O has a yield strength of 83 MPa (12 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 89% of aluminum grades. Elongation at break is 18% and the elastic modulus is 69 GPa (10 Msi).
Thermal6
6066-O is rated for continuous service to 200°C (392 °F). It conducts heat at 154 W/m·K (89 BTU/hr·ft·°F), better than 68% of aluminum grades. Thermal expansion is 23.2 µm/m·K (12.9 µin/in·°F).
Electrical3
6066-O conducts electricity at 43 % IACS, better than 83% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), better than 63% of aluminum grades.
Sustainability4
Producing a kilogram of 6066-O takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 30%.
Manufacturability6
6066-O's machinability is fair (45/100, worse than 72% of aluminum grades); weldability fair (45/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 6066 tempers and conditions
6066 is also supplied in 10 other conditions. The full side-by-side table is on the 6066 overview.
- T6Standard peak-strength condition for structural extrusions, forgings and machined hydraulic/mechanical parts needing more strength than 6061-T6.359 MPa yield · 120 HB
- T651T6 stress-relieved stock for precision machined parts where distortion after material removal must be minimised.359 MPa yield · 120 HB
- T62Re-heat-treated to T6-level strength after forming or welding by the fabricator, when incoming material was O/F/T4.350 MPa yield · 118 HB
- T4Medium-strength, more ductile condition for bending/forming of extrusions that will later be aged to T6 or used as-is.205 MPa yield · 90 HB
- T42Same metallurgy as T4 but heat treated by the fabricator after forming; slightly lower guaranteed properties.200 MPa yield · 88 HB
- OSoftest condition for severe forming or machining of complex blanks before solution treating to T6.83 MPa yield · 43 HB
Working with 6066-O
Is 6066 easy to machine?
One of the better-machining 6xxx alloys thanks to Cu and Mn — sharp polished-flute carbide tools, high speed, chip-clearing coolant; T6/T651 gives cleaner chips than T4.
Can 6066 be welded?
Arc welding is discouraged (Cu-bearing, hot-crack and IGC prone); if required use 4043/4145 filler, low heat input and re-heat-treat plus age, expecting a weak HAZ.
Can 6066 be formed, bent or molded?
Extrudes and forges well at 400–480 °C but cold formability in T6 is poor — bend and cold-form in O or T4 and age afterwards.
What surface finishes work on 6066?
Takes hard sulfuric and chromic anodize well and paints/powder-coats readily; Cu makes clear/bright decorative anodize gray and blotchy, so specify architectural finish on 6061/6063 instead.
6066 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Si | 0.9 – 1.8 | 1.4 |
| Fe | ≤ 0.5 | — |
| Cu | 0.7 – 1.2 | 0.95 |
| Mn | 0.6 – 1.1 | 0.8 |
| Mg | 0.8 – 1.4 | 1.1 |
| Cr | ≤ 0.4 | — |
| Zn | ≤ 0.25 | — |
| Ti | ≤ 0.2 | — |
| Others (each)each | ≤ 0.05 | — |
| Others (total)total | ≤ 0.15 | — |
| Al | balance | — |
6066-O — frequently asked
What is 6066-O used for?
6066-O is typically used for forged shafts, cycle rims, heavy extruded structural sections, high-strength machined brackets, forged suspension and linkage parts and hydraulic and pneumatic bodies. In short: high-strength forging alloy.
What is the yield strength of 6066-O?
6066-O has a typical yield strength of 83 MPa (12 ksi) and a tensile strength of 150 MPa (21.8 ksi) — weaker than 89% of aluminum grades. Strength varies by condition: see the 11 listed tempers.
Is 6066-O easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). One of the better-machining 6xxx alloys thanks to Cu and Mn — sharp polished-flute carbide tools, high speed, chip-clearing coolant; T6/T651 gives cleaner chips than T4.
Can 6066-O be welded?
With care — weldability is rated fair (45/100). Arc welding is discouraged (Cu-bearing, hot-crack and IGC prone); if required use 4043/4145 filler, low heat input and re-heat-treat plus age, expecting a weak HAZ.
What surface finishes work on 6066-O?
Takes hard sulfuric and chromic anodize well and paints/powder-coats readily; Cu makes clear/bright decorative anodize gray and blotchy, so specify architectural finish on 6061/6063 instead.
Can 6066-O be formed, bent or molded?
Extrudes and forges well at 400–480 °C but cold formability in T6 is poor — bend and cold-form in O or T4 and age afterwards.
What is the maximum service temperature of 6066-O?
6066-O is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 6066-O?
Yes — 6066-O is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Aluminum Association International Alloy Designations and Chemical Composition Limits (Teal Sheets) — The Aluminum Association (2018)
- ASTM B221 — Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes — ASTM International (2021)
- EN 573-3 / EN 755-2 — Wrought aluminium alloys, composition and extruded product properties — CEN (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
- Aluminum Standards and Data (typical mechanical & physical property tables) — The Aluminum Association (2017)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.