Aluminum 2A70-T4
Temper
GB 2A70
T4 = solution heat treated and naturally aged
Intermediate state for parts that must be formed or straightened after quenching and then artificially aged.
Values for the T4 condition
Other 2A70 tempers and conditions
2A70 is listed in 5 conditions; see the grade overview at 2A70.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition for deep forming, straightening or intermediate machining before heat treatment. | 120 | 230 | 18 | 65 HB | 48 % IACS |
As fabricated | Raw hot-worked forging or extrusion before solution treatment; used only as a semi-finished supply state. | 160 | 280 | 15 | 80 HB | 42 % IACS |
T4This page Solution heat treated and naturally aged | Intermediate state for parts that must be formed or straightened after quenching and then artificially aged. | 205 | 350 | 18 | 95 HB | 33 % IACS |
T6, stress relieved by compression | Choose for large forgings that must be heavily machined — residual stress is removed so parts stay dimensionally stable. | 345 | 420 | 9 | 118 HB | 38 % IACS |
T6Default Solution heat treated and artificially aged | Standard supply condition for pistons, impellers and hot-running forgings — peak strength plus stable elevated-temperature properties. | 350 | 430 | 10 | 120 HB | 38 % IACS |
What is 2A70-T4?
2A70-T4 is 2A70 in the T4 temper — intermediate state for parts that must be formed or straightened after quenching and then artificially aged. 2A70-T4 has a yield strength of 205 MPa (29.7 ksi) and a tensile strength of 350 MPa (50.8 ksi) — stronger than 54% of aluminum grades. Elongation at break is 18% and the elastic modulus is 72 GPa (10.4 Msi). 2A70-T4 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 505°C (941 °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 — 32 MPa·√m (29.1 ksi·√in), better than 83% of aluminum grades
Limitations
- Needs corrosion protection — 30/100, worse than 98% of aluminum grades
- Limited service temperature — 100°C (212 °F), worse than 91% of aluminum grades
- Difficult to weld — 22/100, worse than 83% of aluminum grades
2A70-T4 properties
Typical room-temperature values for 2A70-T4; 21 are specific to this condition. Other listed values are 2A70 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
2A70-T4 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 505°C (941 °F).
Mechanical15
2A70-T4 has a yield strength of 205 MPa (29.7 ksi) and a tensile strength of 350 MPa (50.8 ksi) — stronger than 54% of aluminum grades. Elongation at break is 18% and the elastic modulus is 72 GPa (10.4 Msi).
Thermal6
2A70-T4 is rated for continuous service to 100°C (212 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 22.3 µm/m·K (12.4 µin/in·°F).
Electrical3
2A70-T4 conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), worse than 98% of aluminum grades.
Sustainability4
Producing a kilogram of 2A70-T4 takes about 200 MJ of energy and emits 12.5 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 10%.
Manufacturability8
2A70-T4's machinability is good (62/100, better than 55% of aluminum grades); weldability poor (22/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 2A70-T4
Is 2A70 easy to machine?
Machines well in T6 with sharp carbide tools and flood coolant, but the hard Al9FeNi/Al7Cu2Fe particles are abrasive — expect faster tool wear than 6061 and use PCD for high-volume piston turning.
Can 2A70 be welded?
Fusion welding is not recommended (hot-cracking, loss of aged strength); join by bolting, riveting, shrink fit or friction/inertia welding with post-weld re-ageing.
Can 2A70 be formed, bent or molded?
Designed for hot die forging and extrusion at roughly 380–460 °C; cold forming in T6 is very limited, form in O or T4 and age afterwards.
What surface finishes work on 2A70?
Use hard or chromic anodizing, chemical conversion coating or Ni/Sn plating for pistons; decorative sulfuric anodizing gives dark uneven color due to Cu-Ni phases.
2A70 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 |
|---|---|---|
| Cu | 1.9 – 2.5 | 2.2 |
| Mg | 1.4 – 1.8 | 1.6 |
| Fedeliberate addition, forms Al9FeNi | 0.9 – 1.5 | 1.2 |
| Niheat-resistance phase former | 0.9 – 1.5 | 1.2 |
| Tigrain refiner | 0.02 – 0.1 | 0.05 |
| Si | ≤ 0.35 | — |
| Mn | ≤ 0.2 | — |
| Zn | ≤ 0.3 | — |
| Others (each)total ≤ 0.15 | ≤ 0.05 | — |
| Al | balance | — |
2A70-T4 — frequently asked
What is 2A70-T4 used for?
2A70-T4 is typically used for forged engine pistons, high-temperature forged structural parts, engine accessory brackets and links, extruded sections for elevated-temperature service, hot-section machined fittings and compressor and engine housings. In short: service to 200 °C; 2618-class piston alloy; abrasive Fe-Ni phases.
What is the yield strength of 2A70-T4?
2A70-T4 has a typical yield strength of 205 MPa (29.7 ksi) and a tensile strength of 350 MPa (50.8 ksi) — stronger than 54% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is 2A70-T4 easy to machine?
Reasonably — machinability is rated good (62/100, better than 55% of aluminum grades). Machines well in T6 with sharp carbide tools and flood coolant, but the hard Al9FeNi/Al7Cu2Fe particles are abrasive — expect faster tool wear than 6061 and use PCD for high-volume piston turning.
Can 2A70-T4 be welded?
Not readily — weldability is rated poor (22/100). Fusion welding is not recommended (hot-cracking, loss of aged strength); join by bolting, riveting, shrink fit or friction/inertia welding with post-weld re-ageing.
What surface finishes work on 2A70-T4?
Use hard or chromic anodizing, chemical conversion coating or Ni/Sn plating for pistons; decorative sulfuric anodizing gives dark uneven color due to Cu-Ni phases.
Can 2A70-T4 be formed, bent or molded?
Designed for hot die forging and extrusion at roughly 380–460 °C; cold forming in T6 is very limited, form in O or T4 and age afterwards.
What is the maximum service temperature of 2A70-T4?
2A70-T4 is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 2A70-T6 and 2A70-O?
T6 is the default condition — standard supply condition for pistons, impellers and hot-running forgings — peak strength plus stable elevated-temperature properties. O: softest condition for deep forming, straightening or intermediate machining before heat treatment. Yield strength is 350 MPa in T6 versus 120 MPa in O.
Sources
- ASM Handbook Vol. 2: Properties and Selection — Nonferrous Alloys (2618 data) — ASM International (1990)
- Aluminum Association Teal Sheets — alloy/temper 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.