Aluminum 2A12-T851
Temper
GB 2A12
T851 = t8, stress relieved by stretching
Best choice for machined structural plate needing high yield strength, low residual stress and improved exfoliation resistance.
Values for the T851 condition
Other 2A12 tempers and conditions
2A12 is listed in 10 conditions; see the grade overview at 2A12.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Choose for deep forming, bending or cold heading before solution treatment. | 75 | 185 | 20 | 47 HB | 50 % IACS |
Strain hardened from hot working only | Low-cost mill-finish bar or profile for non-critical parts that will be heat treated or lightly loaded. | 150 | 260 | 12 | 70 HB | 42 % IACS |
Solution treated by the user and naturally aged | Used when O-temper material is formed first and then heat treated by the fabricator. | 260 | 425 | 19 | 105 HB | 30 % IACS |
T4Default Solution heat treated and naturally aged | Default stocked condition for 2A12 plate, bar and extrusion — best mix of strength, toughness and residual formability. | 325 | 470 | 19 | 120 HB | 30 % IACS |
T3, stress relieved by stretching | Preferred for thick plate that will be heavily machined — low residual stress means minimal distortion. | 325 | 470 | 19 | 120 HB | 30 % IACS |
Solution heat treated, cold worked and naturally aged | Standard aerospace sheet condition where the extra cold work raises yield strength. | 345 | 485 | 18 | 120 HB | 30 % IACS |
T6, heat treated by the user | Same target properties as T6 but achieved by re-heat-treating O or T-temper stock after forming. | 390 | 470 | 9 | 125 HB | 38 % IACS |
Solution heat treated and artificially aged | Pick when a higher yield strength and better stress-corrosion behaviour than T4 are needed, at the cost of ductility. | 395 | 475 | 10 | 125 HB | 38 % IACS |
Solution treated, cold worked, artificially aged | High-yield sheet condition for skins and fittings that must resist creep/exfoliation better than T3. | 450 | 485 | 6 | 128 HB | 38 % IACS |
T851This page T8, stress relieved by stretching | Best choice for machined structural plate needing high yield strength, low residual stress and improved exfoliation resistance. | 450 | 480 | 6 | 128 HB | 38 % IACS |
What is 2A12-T851?
2A12-T851 is 2A12 in the T851 temper — best choice for machined structural plate needing high yield strength, low residual stress and improved exfoliation resistance. 2A12-T851 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 92% of aluminum grades. Elongation at break is 6% and the elastic modulus is 73 GPa (10.6 Msi). 2A12-T851 has a density of 2.78 g/cm³ (0.1 lb/in³), heavier than 74% of aluminum grades. It melts at 502°C (936 °F). T4 is the default condition FabDigit quotes; T851 is available on request or by drawing note.
Advantages
- High strength — 450 MPa (65.3 ksi), better than 92% of aluminum grades
- Easy to machine — 78/100, better than 89% of aluminum grades
Limitations
- Difficult to weld — 15/100, worse than 96% of aluminum grades
- Needs corrosion protection — 38/100, worse than 79% of aluminum grades
2A12-T851 properties
Typical room-temperature values for 2A12-T851; 12 are specific to this condition. Other listed values are 2A12 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
2A12-T851 has a density of 2.78 g/cm³ (0.1 lb/in³), heavier than 74% of aluminum grades. It melts at 502°C (936 °F).
Mechanical15
2A12-T851 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 92% of aluminum grades. Elongation at break is 6% and the elastic modulus is 73 GPa (10.6 Msi).
Thermal6
2A12-T851 is rated for continuous service to 150°C (302 °F). It conducts heat at 151 W/m·K (87.2 BTU/hr·ft·°F), better than 63% of aluminum grades. Thermal expansion is 23.2 µm/m·K (12.9 µin/in·°F).
Electrical3
2A12-T851 conducts electricity at 38 % IACS, better than 61% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of 2A12-T851 takes about 210 MJ of energy and emits 13.5 kg of CO₂ — more than 88% of aluminum grades. Typical recycled content is 15%.
Manufacturability8
2A12-T851's machinability is very good (78/100, better than 89% of aluminum grades); weldability poor (15/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 2A12-T851
Is 2A12 easy to machine?
Machines very well in T4/T351/T851 with sharp carbide tools, high speed and flood coolant; chips are short and surface finish is good, but annealed O temper is gummy.
Can 2A12 be welded?
Not recommended for MIG/TIG fusion welding (hot cracking and severe HAZ strength loss); join by riveting, bolting, adhesive bonding or friction-stir welding.
Can 2A12 be formed, bent or molded?
Form in O or freshly quenched (W) temper and re-age; T3/T4 sheet tolerates moderate bends at large radii, artificially aged tempers are nearly unformable.
What surface finishes work on 2A12?
Chromic or sulfuric anodize plus primer is normal; expect a yellow-brown film, and use clad sheet, Alodine conversion coating or paint for corrosion protection.
2A12 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 |
|---|---|---|
| Cuprimary strengthening element | 3.8 – 4.9 | 4.4 |
| Mg | 1.2 – 1.8 | 1.5 |
| Mn | 0.3 – 0.9 | 0.6 |
| Siimpurity | ≤ 0.5 | — |
| Feimpurity | ≤ 0.5 | — |
| Zn | ≤ 0.3 | — |
| Ni | ≤ 0.1 | — |
| Ti | ≤ 0.15 | — |
| others (each)total ≤ 0.15 | ≤ 0.05 | — |
| Al | balance | — |
2A12-T851 — frequently asked
What is 2A12-T851 used for?
2A12-T851 is typically used for aerospace tooling, precision fixtures, check gauges and jig plates. In short: 2024-equivalent tooling plate; high strength, low corrosion resistance; not fusion weldable.
What is the yield strength of 2A12-T851?
2A12-T851 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 92% of aluminum grades. Strength varies by condition: see the 10 listed tempers.
Is 2A12-T851 easy to machine?
Yes — machinability is rated very good (78/100, better than 89% of aluminum grades). Machines very well in T4/T351/T851 with sharp carbide tools, high speed and flood coolant; chips are short and surface finish is good, but annealed O temper is gummy.
Can 2A12-T851 be welded?
Not readily — weldability is rated poor (15/100). Not recommended for MIG/TIG fusion welding (hot cracking and severe HAZ strength loss); join by riveting, bolting, adhesive bonding or friction-stir welding.
What surface finishes work on 2A12-T851?
Chromic or sulfuric anodize plus primer is normal; expect a yellow-brown film, and use clad sheet, Alodine conversion coating or paint for corrosion protection.
Can 2A12-T851 be formed, bent or molded?
Form in O or freshly quenched (W) temper and re-age; T3/T4 sheet tolerates moderate bends at large radii, artificially aged tempers are nearly unformable.
What is the maximum service temperature of 2A12-T851?
2A12-T851 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 2A12-T4 and 2A12-O?
T4 is the default condition — default stocked condition for 2A12 plate, bar and extrusion — best mix of strength, toughness and residual formability. O: choose for deep forming, bending or cold heading before solution treatment. Yield strength is 325 MPa in T4 versus 75 MPa in O.
Sources
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys (2024 alloy data) — ASM International (1990)
- MMPDS-17 typical/design properties for 2024 — Battelle/FAA (2022)
- Aluminum Association Teal Sheets — International Alloy Designations — The Aluminum Association (2018)
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.