Aluminum 7129-T4
Temper
AA 7129 · UNS A97129
T4 = 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.
Values for the T4 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 |
|---|---|---|---|---|---|---|
Annealed | Softest condition for severe forming or re-solution-treating; not a service temper. | 110 | 230 | 17 | 60 HB | 38 % IACS |
T4This page 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-T4?
7129-T4 is 7129 in the T4 temper — use when parts must be formed or bent after heat treatment and then allowed to age or artificially aged later. 7129-T4 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 56% of aluminum grades. Elongation at break is 18% and the elastic modulus is 70 GPa (10.2 Msi). 7129-T4 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; T4 is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 18%, better than 86% of aluminum grades
- Tough — resists crack growth — 30 MPa·√m (27.3 ksi·√in), better than 76% of aluminum grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
- Needs corrosion protection — 38/100, worse than 79% of aluminum grades
- Low electrical conductivity — 29 % IACS, worse than 78% of aluminum grades
7129-T4 properties
Typical room-temperature values for 7129-T4; 10 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-T4 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-T4 has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 56% of aluminum grades. Elongation at break is 18% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal6
7129-T4 is rated for continuous service to 120°C (248 °F). It conducts heat at 140 W/m·K (80.9 BTU/hr·ft·°F), worse than 52% of aluminum grades. Thermal expansion is 23.4 µm/m·K (13 µin/in·°F).
Electrical3
7129-T4 conducts electricity at 29 % IACS, worse than 78% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of 7129-T4 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-T4's machinability is fair (50/100, worse than 65% of aluminum grades); weldability poor (30/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 7129-T4
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-T4 — frequently asked
What is 7129-T4 used for?
7129-T4 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-T4?
7129-T4 has a typical yield strength of 210 MPa (30.5 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 56% of aluminum grades. Strength varies by condition: see the 7 listed tempers.
Is 7129-T4 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 65% 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-T4 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-T4?
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-T4 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-T4?
7129-T4 is rated for continuous use to about 120°C (248 °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.