Aluminum 7129-O (Annealed)
Temper
AA 7129 · UNS A97129
Softest condition for severe forming or re-solution-treating; not a service temper.
Values for the O condition
Other 7129 tempers and conditions
7129 is listed in 7 conditions; see the grade overview at 7129.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
OThis page Annealed | Softest condition for severe forming or re-solution-treating; not a service temper. | 110 | 230 | 17 | 60 HB | 38 % IACS |
Solution heat treated and naturally aged | Use when parts must be formed or bent after heat treatment and then allowed to age or artificially aged later. | 210 | 330 | 18 | 95 HB | 29 % IACS |
Solution heat treated and overaged for stress-corrosion resistance | Choose for humid, salty or sustained-tension service where stress-corrosion cracking must be avoided, accepting ~10-15 % lower strength. | 290 | 345 | 13 | 105 HB | 39 % IACS |
Overaged for exfoliation-corrosion resistance | Intermediate overage: better exfoliation/SCC resistance than T6 with less strength loss than T73. | 315 | 370 | 12 | 112 HB | 37 % IACS |
Cooled from hot working and artificially aged | Standard low-cost temper for press-quenched automotive bumper and structural extrusions where full T6 solution treatment is not needed. | 325 | 370 | 11 | 112 HB | 33 % IACS |
T6, heat treated by the user | Specified when a formed or annealed part is re-heat-treated to T6-level properties by the fabricator. | 345 | 395 | 10 | 118 HB | 32 % IACS |
T6Default Solution heat treated and artificially aged | Default stocked condition: peak strength for structural extrusions and machined parts in protected or coated service. | 350 | 400 | 11 | 120 HB | 32 % IACS |
What is 7129-O?
7129-O is 7129 in the O temper — softest condition for severe forming or re-solution-treating; not a service temper. 7129-O has a yield strength of 110 MPa (16 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 81% of aluminum grades. Elongation at break is 17% and the elastic modulus is 70 GPa (10.2 Msi). 7129-O has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 480°C (896 °F). T6 is the default condition FabDigit quotes; O is available on request or by drawing note.
Advantages
- Forms and bends easily — 75/100, better than 86% of aluminum grades
- Ductile — tolerates forming and impact — 17%, better than 85% of aluminum grades
- Conducts heat well — 175 W/m·K (101.1 BTU/hr·ft·°F), better than 85% of aluminum grades
- Tough — resists crack growth — 30 MPa·√m (27.3 ksi·√in), better than 76% of aluminum grades
Limitations
- Low strength — 110 MPa (16 ksi), worse than 81% of aluminum grades
- Difficult to machine — 40/100, worse than 81% of aluminum grades
7129-O properties
Typical room-temperature values for 7129-O; 11 are specific to this condition. Other listed values are 7129 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
7129-O has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 480°C (896 °F).
Mechanical13
7129-O has a yield strength of 110 MPa (16 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 81% of aluminum grades. Elongation at break is 17% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
7129-O is rated for continuous service to 150°C (302 °F). It conducts heat at 175 W/m·K (101.1 BTU/hr·ft·°F), better than 85% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7129-O conducts electricity at 38 % IACS, better than 61% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 62% of aluminum grades.
Sustainability4
Producing a kilogram of 7129-O takes about 205 MJ of energy and emits 12.5 kg of CO₂ — more than 76% of aluminum grades. Typical recycled content is 25%.
Manufacturability7
7129-O's machinability is fair (40/100, worse than 81% of aluminum grades); weldability poor (30/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7129-O
Is 7129 easy to machine?
Machines freely in T5/T6 with sharp carbide tools, high speeds and flood coolant; chips are short and surface finish is good, keep tools honed to avoid built-up edge.
Can 7129 be welded?
Cu-bearing 7000 series — avoid fusion welding (hot cracking and severe HAZ/SCC loss); join by riveting, bolting, adhesive or FSW with qualified procedures.
Can 7129 be formed, bent or molded?
Extrudes and hot-forms well (typical 380-450 °C billet); cold bending should be done in O/T4 or with generous radii, as T6 bend limits are tight.
What surface finishes work on 7129?
Takes clear/hard anodize and chromate or chrome-free conversion coatings well and paints readily; polish before anodizing since Zn-Cu content slightly dulls decorative anodic films.
7129 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 | ≤ 0.15 | — |
| Fe | ≤ 0.3 | — |
| Cu | 0.5 – 0.9 | 0.7 |
| Mn | ≤ 0.1 | — |
| Mg | 1.3 – 2 | 1.6 |
| Cr | ≤ 0.1 | — |
| Zn | 4.2 – 5.2 | 4.7 |
| Ti | ≤ 0.05 | — |
| Others (each)each | ≤ 0.05 | — |
| Others (total)total | ≤ 0.15 | — |
| Al | balance | — |
7129-O — frequently asked
What is 7129-O used for?
7129-O is typically used for structural components, transport equipment brackets, bolted and riveted frame members, machined mounting blocks, hot-forged structural fittings and load-bearing extruded profiles. In short: strength-formability balance; T73/T76 for SCC resistance; free-machining aged 7000 series.
What is the yield strength of 7129-O?
7129-O has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 230 MPa (33.4 ksi) — weaker than 81% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is 7129-O easy to machine?
Not especially — machinability is rated fair (40/100, worse than 81% of aluminum grades). Machines freely in T5/T6 with sharp carbide tools, high speeds and flood coolant; chips are short and surface finish is good, keep tools honed to avoid built-up edge.
Can 7129-O be welded?
Not readily — weldability is rated poor (30/100). Cu-bearing 7000 series — avoid fusion welding (hot cracking and severe HAZ/SCC loss); join by riveting, bolting, adhesive or FSW with qualified procedures.
What surface finishes work on 7129-O?
Takes clear/hard anodize and chromate or chrome-free conversion coatings well and paints readily; polish before anodizing since Zn-Cu content slightly dulls decorative anodic films.
Can 7129-O be formed, bent or molded?
Extrudes and hot-forms well (typical 380-450 °C billet); cold bending should be done in O/T4 or with generous radii, as T6 bend limits are tight.
What is the maximum service temperature of 7129-O?
7129-O is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 7129-T6 and 7129-O?
T6 is the default condition — default stocked condition: peak strength for structural extrusions and machined parts in protected or coated service. O: softest condition for severe forming or re-solution-treating; not a service temper. Yield strength is 350 MPa in T6 versus 110 MPa in O.
Sources
- International Alloy Designations and Chemical Composition Limits for Wrought Aluminum (Teal Sheets) — The Aluminum Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (aluminium alloys) — ASM International (2005)
- ASTM B221 — Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles and Tubes — ASTM International (2021)
- MMPDS-class typical property data for 7000-series extrusions — Battelle / FAA (2023)
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.