Aluminum 339.0-T7
Temper
AA 339.0 · UNS A03390
T7 = solution heat treated and overaged (stabilized)
Overaged for maximum dimensional stability and creep resistance in long, hot service; strength drops relative to T5/T6.
Values for the T7 condition
Other 339.0 tempers and conditions
339.0 is listed in 4 conditions; see the grade overview at 339.0.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Untreated permanent-mold castings; used only where cost matters more than hot strength or dimensional stability. | 140 | 215 | 1.5 | 80 HB | 29 % IACS |
T7This page Solution heat treated and overaged (stabilized) | Overaged for maximum dimensional stability and creep resistance in long, hot service; strength drops relative to T5/T6. | 195 | 240 | 1.5 | 90 HB | 30 % IACS |
T5Default Cooled from hot working and artificially aged | Standard production condition for permanent-mold pistons: best combination of hot strength, dimensional stability and cost (no solution treatment/quench distortion). | 234 | 276 | 1 | 100 HB | 28 % IACS |
Solution heat treated and artificially aged | Choose when maximum room-temperature strength and hardness are needed; adds quench distortion risk and cost, and hot-strength advantage over T5 is small. | 255 | 295 | 1 | 115 HB | 27 % IACS |
What is 339.0-T7?
339.0-T7 is 339.0 in the T7 temper — overaged for maximum dimensional stability and creep resistance in long, hot service; strength drops relative to T5/T6. 339.0-T7 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 240 MPa (34.8 ksi) — stronger than 51% of aluminum grades. Elongation at break is 1.5% and the elastic modulus is 81 GPa (11.7 Msi). 339.0-T7 has a density of 2.73 g/cm³ (0.0986 lb/in³), heavier than 61% of aluminum grades. It melts at 505°C (941 °F). T5 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- High service temperature — 275°C (527 °F), better than 99% of aluminum grades
- Low embodied carbon — 9 kg CO₂/kg, better than 99% of aluminum grades
- Stiff — 81 GPa (11.7 Msi), better than 96% of aluminum grades
Limitations
- Limited formability — 5/100, worse than 94% of aluminum grades
- Limited ductility — 1.5%, worse than 91% of aluminum grades
- Needs corrosion protection — 33/100, worse than 91% of aluminum grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 83% of aluminum grades
- Difficult to weld — 23/100, worse than 81% of aluminum grades
339.0-T7 properties
Typical room-temperature values for 339.0-T7; 20 are specific to this condition. Other listed values are 339.0 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
339.0-T7 has a density of 2.73 g/cm³ (0.0986 lb/in³), heavier than 61% of aluminum grades. It melts at 505°C (941 °F).
Mechanical12
339.0-T7 has a yield strength of 195 MPa (28.3 ksi) and a tensile strength of 240 MPa (34.8 ksi) — stronger than 51% of aluminum grades. Elongation at break is 1.5% and the elastic modulus is 81 GPa (11.7 Msi).
Thermal6
339.0-T7 is rated for continuous service to 275°C (527 °F). It conducts heat at 125 W/m·K (72.2 BTU/hr·ft·°F), worse than 72% of aluminum grades. Thermal expansion is 19.4 µm/m·K (10.8 µin/in·°F).
Electrical3
339.0-T7 conducts electricity at 30 % IACS, worse than 73% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (33/100), worse than 91% of aluminum grades.
Sustainability4
Producing a kilogram of 339.0-T7 takes about 150 MJ of energy and emits 9 kg of CO₂ — less than 97% of aluminum grades. Typical recycled content is 60%.
Manufacturability8
339.0-T7's machinability is fair (42/100, worse than 77% of aluminum grades); weldability poor (23/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 339.0-T7
Is 339.0 easy to machine?
Abrasive primary Si and Ni-aluminides demand PCD or diamond-coated carbide, high speed with low feed and flood coolant; finish-machine after aging for dimensional stability.
Can 339.0 be welded?
Poor fusion weldability (2–3 % Cu plus low solidus → hot cracking and porosity); repair only with 4145/4047 filler under preheat, or use mechanical joints.
Can 339.0 be formed, bent or molded?
Permanent-mold (gravity die) casting alloy with good fluidity and low shrinkage; grain refine/modify the melt, degas well, and use directional chilling on piston crowns.
What surface finishes work on 339.0?
Decorative anodizing is poor (dark, mottled); use hard anodize or ferrous-oxalate/graphite coatings on crowns and skirts, tin plating for break-in, or chromate-free primer plus paint elsewhere.
339.0 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 | 11 – 13 | 12 |
| Cu | 1.5 – 3 | 2.3 |
| Mg | 0.5 – 1.5 | 1 |
| Niraises elevated-temperature strength | 0.5 – 1.5 | 1 |
| Feimpurity limit | ≤ 1.2 | — |
| Mn | ≤ 0.5 | — |
| Zn | ≤ 1 | — |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.15 | — |
| Al | balance | — |
339.0-T7 — frequently asked
What is 339.0-T7 used for?
339.0-T7 is typically used for automotive pistons, high-temperature engine components, diesel piston crowns, compressor and pump pistons, turbocharged-engine cast hardware and wear surfaces running hot. In short: highest service temperature here; ni-bearing piston alloy; very abrasive to tooling.
What is the yield strength of 339.0-T7?
339.0-T7 has a typical yield strength of 195 MPa (28.3 ksi) and a tensile strength of 240 MPa (34.8 ksi) — stronger than 51% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is 339.0-T7 easy to machine?
Not especially — machinability is rated fair (42/100, worse than 77% of aluminum grades). Abrasive primary Si and Ni-aluminides demand PCD or diamond-coated carbide, high speed with low feed and flood coolant; finish-machine after aging for dimensional stability.
Can 339.0-T7 be welded?
Not readily — weldability is rated poor (23/100). Poor fusion weldability (2–3 % Cu plus low solidus → hot cracking and porosity); repair only with 4145/4047 filler under preheat, or use mechanical joints.
What surface finishes work on 339.0-T7?
Decorative anodizing is poor (dark, mottled); use hard anodize or ferrous-oxalate/graphite coatings on crowns and skirts, tin plating for break-in, or chromate-free primer plus paint elsewhere.
Can 339.0-T7 be formed, bent or molded?
Permanent-mold (gravity die) casting alloy with good fluidity and low shrinkage; grain refine/modify the melt, degas well, and use directional chilling on piston crowns.
What is the maximum service temperature of 339.0-T7?
339.0-T7 is rated for continuous use to about 275°C (527 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 339.0-T5 and 339.0-F?
T5 is the default condition — standard production condition for permanent-mold pistons: best combination of hot strength, dimensional stability and cost (no solution treatment/quench distortion). F: untreated permanent-mold castings; used only where cost matters more than hot strength or dimensional stability. Yield strength is 234 MPa in T5 versus 140 MPa in F.
Sources
- Registration Record of Aluminum Association Alloy Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot ("Pink Sheets") — Aluminum Association (2018)
- ASTM B108 / B26 — Aluminum-Alloy Permanent Mold and Sand Castings — ASTM International (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASM Handbook Vol. 13 — Corrosion — ASM International (2005)
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.