Aluminum AC1A-T7
Temper
JIS AC1A
T7 = solution heat treated and overaged (stabilized)
Overaged for dimensional stability, better toughness and improved resistance to intergranular/stress-corrosion attack; used for parts running hot (150–250 °C).
Values for the T7 condition
Other AC1A tempers and conditions
AC1A is listed in 4 conditions; see the grade overview at AC1A.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Lowest cost condition for non-critical parts or blanks that will be heat treated later; strength is modest and the structure is cored. | 95 | 165 | 5 | 55 HB | 36 % IACS |
Solution heat treated and naturally aged | Best combination of strength and ductility/toughness; choose when impact loading or elongation matters more than peak strength. | 180 | 295 | 8 | 70 HB | 27 % IACS |
T7This page Solution heat treated and overaged (stabilized) | Overaged for dimensional stability, better toughness and improved resistance to intergranular/stress-corrosion attack; used for parts running hot (150–250 °C). | 245 | 305 | 3.5 | 88 HB | 35 % IACS |
T6Default Solution heat treated and artificially aged | Standard high-strength condition for structural castings; pick it when maximum tensile/yield strength and hardness are required and ductility can be traded away. | 250 | 335 | 4 | 95 HB | 31 % IACS |
What is AC1A-T7?
AC1A-T7 is AC1A in the T7 temper — overaged for dimensional stability, better toughness and improved resistance to intergranular/stress-corrosion attack; used for parts running hot (150–250 °C). AC1A-T7 has a yield strength of 245 MPa (35.5 ksi) and a tensile strength of 305 MPa (44.2 ksi) — stronger than 64% of aluminum grades. Elongation at break is 3.5% and the elastic modulus is 71 GPa (10.3 Msi). AC1A-T7 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 545°C (1,013 °F). T6 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- High service temperature — 230°C (446 °F), better than 95% of aluminum grades
- Tough — resists crack growth — 33 MPa·√m (30 ksi·√in), better than 87% of aluminum grades
- Easy to machine — 72/100, better than 80% of aluminum grades
Limitations
- Limited ductility — 3.5%, worse than 76% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
- Needs corrosion protection — 40/100, worse than 75% of aluminum grades
AC1A-T7 properties
Typical room-temperature values for AC1A-T7; 12 are specific to this condition. Other listed values are AC1A reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
AC1A-T7 has a density of 2.8 g/cm³ (0.101 lb/in³), heavier than 81% of aluminum grades. It melts at 545°C (1,013 °F).
Mechanical12
AC1A-T7 has a yield strength of 245 MPa (35.5 ksi) and a tensile strength of 305 MPa (44.2 ksi) — stronger than 64% of aluminum grades. Elongation at break is 3.5% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
AC1A-T7 is rated for continuous service to 230°C (446 °F). It conducts heat at 140 W/m·K (80.9 BTU/hr·ft·°F), worse than 52% of aluminum grades. Thermal expansion is 22.5 µm/m·K (12.5 µin/in·°F).
Electrical3
AC1A-T7 conducts electricity at 35 % IACS, better than 52% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 75% of aluminum grades.
Sustainability4
Producing a kilogram of AC1A-T7 takes about 190 MJ of energy and emits 12.5 kg of CO₂ — less than 89% of aluminum grades. Typical recycled content is 20%.
Manufacturability7
AC1A-T7's machinability is very good (72/100, better than 80% of aluminum grades); weldability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AC1A-T7
Is AC1A easy to machine?
Machines very well in T4/T6 with sharp carbide or PCD tooling, high speed and flood coolant; chips are short and finishes are good, but porosity can show up as surface pinholes.
Can AC1A be welded?
Poor fusion weldability — Al-Cu castings hot-tear readily; if repair welding is unavoidable use 2319 (Al-Cu) filler, preheat, and re-solution/re-age afterwards.
Can AC1A be formed, bent or molded?
Sand and permanent-mold casting only; needs strong directional solidification with generous risers, chills and controlled pouring to fight hot tearing and interdendritic shrinkage — low pressure-tightness.
What surface finishes work on AC1A?
Painting or chromate/anodize-plus-seal is normally required for corrosion protection; hard anodize is feasible but films are dark and uneven due to the copper, and polished surfaces are limited by microporosity.
AC1A 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 |
|---|---|---|
| Cumain strengthening element | 4 – 5 | 4.5 |
| Mg | 0.15 – 0.35 | 0.25 |
| Tigrain refiner | 0.05 – 0.3 | 0.2 |
| Siimpurity limit | ≤ 0.2 | — |
| Feimpurity limit | ≤ 0.25 | — |
| Mn | ≤ 0.1 | — |
| Zn | ≤ 0.1 | — |
| Ni | ≤ 0.05 | — |
| Sn | ≤ 0.05 | — |
| Pb | ≤ 0.05 | — |
| Al | balance | — |
AC1A-T7 — frequently asked
What is AC1A-T7 used for?
AC1A-T7 is typically used for aircraft structural castings, high-strength brackets and engine mounts. In short: highest-strength cast aluminum; heat-treatable Al-Cu casting alloy; difficult to cast.
What is the yield strength of AC1A-T7?
AC1A-T7 has a typical yield strength of 245 MPa (35.5 ksi) and a tensile strength of 305 MPa (44.2 ksi) — stronger than 64% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC1A-T7 easy to machine?
Yes — machinability is rated very good (72/100, better than 80% of aluminum grades). Machines very well in T4/T6 with sharp carbide or PCD tooling, high speed and flood coolant; chips are short and finishes are good, but porosity can show up as surface pinholes.
Can AC1A-T7 be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability — Al-Cu castings hot-tear readily; if repair welding is unavoidable use 2319 (Al-Cu) filler, preheat, and re-solution/re-age afterwards.
What surface finishes work on AC1A-T7?
Painting or chromate/anodize-plus-seal is normally required for corrosion protection; hard anodize is feasible but films are dark and uneven due to the copper, and polished surfaces are limited by microporosity.
Can AC1A-T7 be formed, bent or molded?
Sand and permanent-mold casting only; needs strong directional solidification with generous risers, chills and controlled pouring to fight hot tearing and interdendritic shrinkage — low pressure-tightness.
What is the maximum service temperature of AC1A-T7?
AC1A-T7 is rated for continuous use to about 230°C (446 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC1A-T6 and AC1A-F?
T6 is the default condition — standard high-strength condition for structural castings; pick it when maximum tensile/yield strength and hardness are required and ductility can be traded away. F: lowest cost condition for non-critical parts or blanks that will be heat treated later; strength is modest and the structure is cored. Yield strength is 250 MPa in T6 versus 95 MPa in F.
Sources
- JIS H 5202 Aluminium alloy castings — JSA (2010)
- GB/T 1173 (ZL201/ZL201A) — SAC (2013)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (Aluminium casting alloys 201.0/204.0) — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASM Handbook Vol.13B — Corrosion: Materials — 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.