Aluminum AC2A-T7
Temper
JIS AC2A
T7 = solution heat treated and overaged (stabilized)
Pick the solution treated and overaged state when dimensional stability and long-term service to 200 °C outweigh strength; tensile falls to 215 MPa while elongation rises to 2.5%.
Values for the T7 condition
Other AC2A tempers and conditions
AC2A is listed in 4 conditions; see the grade overview at AC2A.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Pick the as-cast sand or permanent-mould state for lowest cost and best dimensional stability in low to moderately loaded housings and oil-gallery bodies; 190 MPa tensile, 125 MPa yield. | 125 | 190 | 2 | 70 HB | 27 % IACS |
T7This page Solution heat treated and overaged (stabilized) | Pick the solution treated and overaged state when dimensional stability and long-term service to 200 °C outweigh strength; tensile falls to 215 MPa while elongation rises to 2.5%. | 150 | 215 | 2.5 | 75 HB | 30 % IACS |
T6Default Solution heat treated and artificially aged | Use solution heat treated and artificially aged castings for the highest strength state, 250 MPa tensile and 85 HB, in load-bearing housings, cylinder blocks and brackets needing wear resistance. | 170 | 250 | 2 | 85 HB | 27 % IACS |
Cooled from hot working and artificially aged | Choose when the casting is only artificially aged without solution treatment: hardness reaches 80 HB with better machinability and far less distortion and cracking risk than T6. | 180 | 205 | 1.5 | 80 HB | 28 % IACS |
What is AC2A-T7?
AC2A-T7 is AC2A in the T7 temper — pick the solution treated and overaged state when dimensional stability and long-term service to 200 °C outweigh strength; tensile falls to 215 MPa while elongation rises to 2.5%. AC2A-T7 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 215 MPa (31.2 ksi) — weaker than 65% of aluminum grades. Elongation at break is 2.5% and the elastic modulus is 74 GPa (10.7 Msi). AC2A-T7 has a density of 2.79 g/cm³ (0.101 lb/in³), heavier than 77% of aluminum grades. It melts at 516°C (961 °F). T6 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
Limitations
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Limited ductility — 2.5%, worse than 83% of aluminum grades
- Poor heat conductor — 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades
AC2A-T7 properties
Typical room-temperature values for AC2A-T7; 20 are specific to this condition. Other listed values are AC2A reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
AC2A-T7 has a density of 2.79 g/cm³ (0.101 lb/in³), heavier than 77% of aluminum grades. It melts at 516°C (961 °F).
Mechanical12
AC2A-T7 has a yield strength of 150 MPa (21.8 ksi) and a tensile strength of 215 MPa (31.2 ksi) — weaker than 65% of aluminum grades. Elongation at break is 2.5% and the elastic modulus is 74 GPa (10.7 Msi).
Thermal6
AC2A-T7 is rated for continuous service to 200°C (392 °F). It conducts heat at 121 W/m·K (69.9 BTU/hr·ft·°F), worse than 76% of aluminum grades. Thermal expansion is 21.5 µm/m·K (11.9 µin/in·°F).
Electrical3
AC2A-T7 conducts electricity at 30 % IACS, worse than 73% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 62% of aluminum grades.
Sustainability4
Producing a kilogram of AC2A-T7 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 80%.
Manufacturability8
AC2A-T7's machinability is good (68/100, better than 67% of aluminum grades); weldability fair (35/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AC2A-T7
Is AC2A easy to machine?
Copper content plus eutectic silicon gives better machinability than straight Al-Si alloys, with good chip breaking. Use diamond or coated carbide tooling at high speed and light feed for a good surface finish.
Can AC2A be welded?
Weldability is poor and the high Cu content makes the alloy hot-crack prone. For repair use 4043/4145 filler with 150-200 °C preheat, then re-heat-treat to T6 to restore properties.
Can AC2A be formed, bent or molded?
Suited to sand and gravity permanent-mould casting; fluidity is moderate to good and hot-tearing tendency is moderate. Provide good feeding with adequate risers and avoid very thin wall sections.
What surface finishes work on AC2A?
Chemical conversion coating or painting is standard. Decorative anodizing is not recommended because films come out grey and dull; hard anodize or powder coat can be used, and polishing is limited by the silicon particles.
AC2A 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 |
|---|---|---|
| SiJIS H5202 AC2A | 4 – 6 | 5 |
| Cu | 3 – 4.5 | 3.8 |
| Mg | ≤ 0.25 | — |
| Zn | ≤ 0.55 | — |
| Femaximum impurity limit | ≤ 0.8 | — |
| Mn | ≤ 0.55 | — |
| Ni | ≤ 0.3 | — |
| Ti | ≤ 0.2 | — |
| Cr | ≤ 0.15 | — |
| Pb | ≤ 0.15 | — |
| Sn | ≤ 0.05 | — |
| Al | balance | — |
AC2A-T7 — frequently asked
What is AC2A-T7 used for?
AC2A-T7 is typically used for gearbox housings, pump bodies and general machinery castings. In short: balanced Al-Cu-Si casting alloy; better machining than Al-Si; moderate hot-tear risk.
What is the yield strength of AC2A-T7?
AC2A-T7 has a typical yield strength of 150 MPa (21.8 ksi) and a tensile strength of 215 MPa (31.2 ksi) — weaker than 65% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC2A-T7 easy to machine?
Reasonably — machinability is rated good (68/100, better than 67% of aluminum grades). Copper content plus eutectic silicon gives better machinability than straight Al-Si alloys, with good chip breaking. Use diamond or coated carbide tooling at high speed and light feed for a good surface finish.
Can AC2A-T7 be welded?
With care — weldability is rated fair (35/100). Weldability is poor and the high Cu content makes the alloy hot-crack prone. For repair use 4043/4145 filler with 150-200 °C preheat, then re-heat-treat to T6 to restore properties.
What surface finishes work on AC2A-T7?
Chemical conversion coating or painting is standard. Decorative anodizing is not recommended because films come out grey and dull; hard anodize or powder coat can be used, and polishing is limited by the silicon particles.
Can AC2A-T7 be formed, bent or molded?
Suited to sand and gravity permanent-mould casting; fluidity is moderate to good and hot-tearing tendency is moderate. Provide good feeding with adequate risers and avoid very thin wall sections.
What is the maximum service temperature of AC2A-T7?
AC2A-T7 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC2A-T6 and AC2A-F?
T6 is the default condition — use solution heat treated and artificially aged castings for the highest strength state, 250 MPa tensile and 85 HB, in load-bearing housings, cylinder blocks and brackets needing wear resistance. F: pick the as-cast sand or permanent-mould state for lowest cost and best dimensional stability in low to moderately loaded housings and oil-gallery bodies; 190 MPa tensile, 125 MPa yield. Yield strength is 170 MPa in T6 versus 125 MPa in F.
Sources
- JIS H 5202 Aluminium alloy castings — JSA (2010)
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys (319.0/A319.0) — ASM International (1990)
- Aluminum Association Pink Sheets — Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot — The Aluminum Association (2018)
- GB/T 1173 (ZL203) (2013)
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.