Aluminum 771.0-T51
Temper
AA 771.0 · UNS A07710 · also 71A
T51 = t5, stress relieved by stretching
Mild age used mainly to relieve casting stress and stabilize dimensions with modest strengthening.
Values for the T51 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 |
T51This page 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 |
T71Default 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-T51?
771.0-T51 is 771.0 in the T51 temper — mild age used mainly to relieve casting stress and stabilize dimensions with modest strengthening. 771.0-T51 has a yield strength of 186 MPa (27 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 52% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi). 771.0-T51 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). T71 is the default condition FabDigit quotes; T51 is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% of aluminum grades
- Easy to machine — 75/100, better than 86% of aluminum grades
Limitations
- Limited formability — 10/100, worse than 80% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
- Limited service temperature — 120°C (248 °F), worse than 79% of aluminum grades
771.0-T51 properties
Typical room-temperature values for 771.0-T51; 19 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-T51 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-T51 has a yield strength of 186 MPa (27 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 52% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
771.0-T51 is rated for continuous service to 120°C (248 °F). It conducts heat at 134 W/m·K (77.4 BTU/hr·ft·°F), worse than 60% of aluminum grades. Thermal expansion is 24 µm/m·K (13.3 µin/in·°F).
Electrical3
771.0-T51 conducts electricity at 36 % IACS, better than 55% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 58% of aluminum grades.
Sustainability4
Producing a kilogram of 771.0-T51 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-T51's machinability is very good (75/100, better than 86% of aluminum grades); weldability fair (45/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 771.0-T51
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-T51 — frequently asked
What is 771.0-T51 used for?
771.0-T51 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-T51?
771.0-T51 has a typical yield strength of 186 MPa (27 ksi) and a tensile strength of 220 MPa (31.9 ksi) — weaker than 52% of aluminum grades. Strength varies by condition: see the 8 listed tempers.
Is 771.0-T51 easy to machine?
Yes — machinability is rated very good (75/100, better than 86% 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-T51 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-T51?
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-T51 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-T51?
771.0-T51 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 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.