Aluminum AC9A-T6
Temper · default condition
JIS AC9A
T6 = solution heat treated and artificially aged
Peak-strength, peak-hardness condition — choose for highly loaded pistons and wear surfaces.
Values for the T6 condition
Other AC9A tempers and conditions
AC9A is listed in 4 conditions; see the grade overview at AC9A.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | As-cast condition; lowest cost, used where dimensional stability matters more than strength. | 140 | 165 | 0.5 | 90 HB | 26 % IACS |
Solution heat treated and overaged (stabilized) | Overaged for maximum dimensional stability at elevated temperature; pick for pistons running hot for long durations. | 160 | 180 | 0.6 | 100 HB | 27 % IACS |
Cooled from hot working and artificially aged | Low-distortion aging straight from the mould; standard for mass-produced gravity/low-pressure cast pistons. | 170 | 190 | 0.4 | 105 HB | 26 % IACS |
T6DefaultThis page Solution heat treated and artificially aged | Peak-strength, peak-hardness condition — choose for highly loaded pistons and wear surfaces. | 190 | 210 | 0.4 | 135 HB | 24 % IACS |
What is AC9A-T6?
AC9A-T6 is AC9A in the T6 temper — peak-strength, peak-hardness condition — choose for highly loaded pistons and wear surfaces. AC9A-T6 has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 210 MPa (30.5 ksi) — weaker than 52% of aluminum grades. Elongation at break is 0.4% and the elastic modulus is 88 GPa (12.8 Msi). AC9A-T6 has a density of 2.66 g/cm³ (0.0961 lb/in³), lighter than 84% of aluminum grades. It melts at 510°C (950 °F).
Advantages
- Stiff — 88 GPa (12.8 Msi), better than 98% of aluminum grades
- High service temperature — 250°C (482 °F), better than 97% of aluminum grades
- Low embodied carbon — 10.5 kg CO₂/kg, better than 95% of aluminum grades
Limitations
- Limited ductility — 0.4%, worse than 100% of aluminum grades
- Low fracture toughness — 11 MPa·√m (10 ksi·√in), worse than 100% of aluminum grades
- Difficult to machine — 25/100, worse than 96% of aluminum grades
- Low electrical conductivity — 24 % IACS, worse than 95% of aluminum grades
- Limited formability — 5/100, worse than 94% of aluminum grades
AC9A-T6 properties
Typical room-temperature values for AC9A-T6; 22 are specific to this condition. Other listed values are AC9A reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
AC9A-T6 has a density of 2.66 g/cm³ (0.0961 lb/in³), lighter than 84% of aluminum grades. It melts at 510°C (950 °F).
Mechanical16
AC9A-T6 has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 210 MPa (30.5 ksi) — weaker than 52% of aluminum grades. Elongation at break is 0.4% and the elastic modulus is 88 GPa (12.8 Msi).
Thermal6
AC9A-T6 is rated for continuous service to 250°C (482 °F). It conducts heat at 120 W/m·K (69.3 BTU/hr·ft·°F), worse than 80% of aluminum grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
AC9A-T6 conducts electricity at 24 % IACS, worse than 95% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (44/100), worse than 65% of aluminum grades.
Sustainability4
Producing a kilogram of AC9A-T6 takes about 155 MJ of energy and emits 10.5 kg of CO₂ — less than 94% of aluminum grades. Typical recycled content is 35%.
Manufacturability8
AC9A-T6's machinability is poor (25/100, worse than 96% of aluminum grades); weldability poor (20/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AC9A-T6
Is AC9A easy to machine?
Primary silicon crystals are highly abrasive — use PCD or diamond-coated tooling, high speed / light feed with flood coolant; carbide tools wear out rapidly.
Can AC9A be welded?
Essentially non-weldable for structural repair — Cu-bearing hypereutectic casting is hot-crack prone; use 4047/4145 filler only for cosmetic repair with preheat.
Can AC9A be formed, bent or molded?
Gravity, low-pressure or squeeze cast at 730–780 °C with phosphorus (Cu-P / P-Cu master alloy) modification to refine primary Si; avoid Na/Sr modifiers which coarsen primary Si.
What surface finishes work on AC9A?
Hard anodize or ferrous/graphite coating for ring-groove and skirt wear areas; decorative anodizing gives a dark, mottled film — tin/graphite skirt coating is the common alternative.
AC9A 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 |
|---|---|---|
| Sihypereutectic; P-modified to refine primary Si | 22 – 24 | 23 |
| Cu | 0.5 – 1.5 | 1 |
| Mg | 0.5 – 1.5 | 1 |
| Nielevated-temperature strength | 0.5 – 1.5 | 1 |
| Fe | ≤ 0.8 | 0.5 |
| Mn | ≤ 0.5 | — |
| Zn | ≤ 0.2 | — |
| Ti | ≤ 0.2 | — |
| Cr | ≤ 0.1 | — |
| Sn | ≤ 0.05 | — |
| Pb | ≤ 0.05 | — |
| Al | balance | — |
AC9A-T6 — frequently asked
What is AC9A-T6 used for?
AC9A-T6 is typically used for high-performance engine pistons, wear-resistant sleeves, cylinder liners, compressor pistons, linerless cylinder blocks and pump wear plates. In short: hypereutectic wear grade; lowest thermal expansion; requires PCD tooling.
What is the yield strength of AC9A-T6?
AC9A-T6 has a typical yield strength of 190 MPa (27.6 ksi) and a tensile strength of 210 MPa (30.5 ksi) — weaker than 52% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC9A-T6 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 96% of aluminum grades). Primary silicon crystals are highly abrasive — use PCD or diamond-coated tooling, high speed / light feed with flood coolant; carbide tools wear out rapidly.
Can AC9A-T6 be welded?
Not readily — weldability is rated poor (20/100). Essentially non-weldable for structural repair — Cu-bearing hypereutectic casting is hot-crack prone; use 4047/4145 filler only for cosmetic repair with preheat.
What surface finishes work on AC9A-T6?
Hard anodize or ferrous/graphite coating for ring-groove and skirt wear areas; decorative anodizing gives a dark, mottled film — tin/graphite skirt coating is the common alternative.
Can AC9A-T6 be formed, bent or molded?
Gravity, low-pressure or squeeze cast at 730–780 °C with phosphorus (Cu-P / P-Cu master alloy) modification to refine primary Si; avoid Na/Sr modifiers which coarsen primary Si.
What is the maximum service temperature of AC9A-T6?
AC9A-T6 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC9A-T6 and AC9A-F?
T6 is the default condition — peak-strength, peak-hardness condition — choose for highly loaded pistons and wear surfaces. F: as-cast condition; lowest cost, used where dimensional stability matters more than strength. Yield strength is 190 MPa in T6 versus 140 MPa in F.
Sources
- JIS H5202 Aluminium alloy castings — JSA (2010)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASTM B108 / Aluminum Association Pink Sheets (A390.0) — ASTM / AA (2018)
- GB/T 1173 (ZL109 ) — SAC (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.