Aluminum 771.0-T71
Precip hard · default condition
AA 771.0 · UNS A07710 · also 71A
T71 = solution heat treated and overaged
Highest-strength, most dimensionally stable and most SCC-resistant temper — the usual production condition for 771.0 castings.
Values for the T71 condition
Other 771.0 tempers and conditions
771.0 is listed in 8 conditions; see the grade overview at 771.0.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | As-poured condition; used only as the starting point for aging or where strength is not critical. | 125 | 200 | 3 | 60 HB | 32 % IACS |
Cooled from hot working, cold worked and naturally aged | Choose when dimensional stability and machining freedom matter more than strength. | 150 | 220 | 2 | 70 HB | 38 % IACS |
T5, stress relieved by stretching | Mild age used mainly to relieve casting stress and stabilize dimensions with modest strengthening. | 186 | 220 | 3 | 70 HB | 36 % IACS |
T5, stress relieved by compression | Best compromise of dimensional stability and moderate strength for machined housings and fixtures. | 207 | 248 | 1.5 | 70 HB | 36 % IACS |
As-cast plus modified stabilizing/aging cycle | Registered variant of the T52 cycle giving similar strength with tighter dimensional control. | 207 | 248 | 1.5 | 70 HB | 36 % IACS |
Solution heat treated and artificially aged | Full heat treatment for the best strength–ductility balance when quench distortion can be tolerated. | 241 | 290 | 5 | 75 HB | 32 % IACS |
Cooled from hot working and artificially aged | Highest strength without any solution treatment/quench — the classic low-distortion route for complex castings. | 262 | 290 | 1.5 | 85 HB | 34 % IACS |
T71DefaultThis page Solution heat treated and overaged | Highest-strength, most dimensionally stable and most SCC-resistant temper — the usual production condition for 771.0 castings. | 310 | 330 | 2 | 90 HB | 35 % IACS |
What is 771.0-T71?
771.0-T71 is 771.0 in the T71 condition — highest-strength, most dimensionally stable and most SCC-resistant temper — the usual production condition for 771.0 castings. 771.0-T71 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 78% of aluminum grades. Elongation at break is 2% and the elastic modulus is 71 GPa (10.3 Msi). 771.0-T71 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 604°C (1,119 °F).
Advantages
- Easy to machine — 80/100, better than 92% of aluminum grades
- Polishes to a fine finish — 70/100, better than 87% of aluminum grades
- High strength — 310 MPa (45 ksi), better than 78% of aluminum grades
Limitations
- Limited ductility — 2%, worse than 87% of aluminum grades
- Limited formability — 10/100, worse than 80% of aluminum grades
771.0-T71 properties
Typical room-temperature values for 771.0-T71; 10 are specific to this condition. Other listed values are 771.0 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
771.0-T71 has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 604°C (1,119 °F).
Mechanical10
771.0-T71 has a yield strength of 310 MPa (45 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 78% of aluminum grades. Elongation at break is 2% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
771.0-T71 is rated for continuous service to 150°C (302 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 24 µm/m·K (13.3 µin/in·°F).
Electrical3
771.0-T71 conducts electricity at 35 % IACS, better than 52% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 51% of aluminum grades.
Sustainability4
Producing a kilogram of 771.0-T71 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 25%.
Manufacturability8
771.0-T71's machinability is very good (80/100, better than 92% of aluminum grades); weldability fair (45/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 771.0-T71
Is 771.0 easy to machine?
Excellent — machines to a bright, burr-free finish with polished-flute carbide, high speed and low feed pressure; T5/T71 chip better than as-cast F.
Can 771.0 be welded?
GTAW/GMAW possible with 5356 or 4043 filler, but the Al-Zn-Mg matrix is hot-crack and SCC sensitive; re-age after welding and avoid weld repairs in stressed areas.
Can 771.0 be formed, bent or molded?
Sand and permanent-mold casting only; fluidity is moderate and hot-tear sensitivity high, so use generous fillets, chills and well-fed risering; the alloy self-ages so many parts skip solution treatment.
What surface finishes work on 771.0?
Takes clear and hard anodize well (slightly grey tone), accepts chromate/ trivalent conversion coating and paint; polish before anodizing for cosmetic parts.
771.0 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 | ≤ 0.15 | — |
| Cu | ≤ 0.1 | — |
| Mn | ≤ 0.1 | — |
| Mg | 0.8 – 1 | 0.9 |
| Cr | 0.06 – 0.2 | 0.13 |
| Zn | 6.5 – 7.5 | 7 |
| Tigrain refiner | 0.1 – 0.2 | 0.15 |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
771.0-T71 — frequently asked
What is 771.0-T71 used for?
771.0-T71 is typically used for aircraft castings, instrument housings and structural parts. In short: strongest 7xx.x casting alloy; high strength-to-weight ratio; machines to bright finish.
What is the yield strength of 771.0-T71?
771.0-T71 has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 78% of aluminum grades. Strength varies by condition: see the 8 listed tempers.
Is 771.0-T71 easy to machine?
Yes — machinability is rated very good (80/100, better than 92% of aluminum grades). Excellent — machines to a bright, burr-free finish with polished-flute carbide, high speed and low feed pressure; T5/T71 chip better than as-cast F.
Can 771.0-T71 be welded?
With care — weldability is rated fair (45/100). GTAW/GMAW possible with 5356 or 4043 filler, but the Al-Zn-Mg matrix is hot-crack and SCC sensitive; re-age after welding and avoid weld repairs in stressed areas.
What surface finishes work on 771.0-T71?
Takes clear and hard anodize well (slightly grey tone), accepts chromate/ trivalent conversion coating and paint; polish before anodizing for cosmetic parts.
Can 771.0-T71 be formed, bent or molded?
Sand and permanent-mold casting only; fluidity is moderate and hot-tear sensitivity high, so use generous fillets, chills and well-fed risering; the alloy self-ages so many parts skip solution treatment.
What is the maximum service temperature of 771.0-T71?
771.0-T71 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 771.0-T71 and 771.0-F?
T71 is the default condition — highest-strength, most dimensionally stable and most SCC-resistant temper — the usual production condition for 771.0 castings. F: as-poured condition; used only as the starting point for aging or where strength is not critical. Yield strength is 310 MPa in T71 versus 125 MPa in F.
Sources
- ASTM B26/B26M — Aluminum-Alloy Sand Castings — ASTM International (2018)
- Registration Record of Aluminum Association Alloy Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot ('Pink Sheets') — The Aluminum Association (2018)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 15 — Casting — ASM International (2008)
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.