Aluminum AC9B-T7
Temper
JIS AC9B
T7 = solution heat treated and overaged (stabilized)
Choose for maximum dimensional/thermal stability in long-running hot components, accepting some strength loss versus T6.
Values for the T7 condition
Other AC9B tempers and conditions
AC9B is listed in 4 conditions; see the grade overview at AC9B.
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 wear castings where dimensional stabilization is not required. | 150 | 170 | 0.5 | 100 HB | 26 % IACS |
T7This page Solution heat treated and overaged (stabilized) | Choose for maximum dimensional/thermal stability in long-running hot components, accepting some strength loss versus T6. | 165 | 185 | 0.8 | 110 HB | 27 % IACS |
Cooled from hot working and artificially aged | Choose when moderate strengthening and dimensional stabilization are needed without the distortion risk of solution treatment. | 175 | 190 | 0.5 | 115 HB | 26 % IACS |
T6Default Solution heat treated and artificially aged | Standard condition for maximum strength and hardness in pistons and wear parts operating up to about 250 °C. | 200 | 220 | 0.5 | 140 HB | 25 % IACS |
What is AC9B-T7?
AC9B-T7 is AC9B in the T7 temper — choose for maximum dimensional/thermal stability in long-running hot components, accepting some strength loss versus T6. AC9B-T7 has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 58% of aluminum grades. Elongation at break is 0.8% and the elastic modulus is 82 GPa (11.9 Msi). AC9B-T7 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 507°C (945 °F). T6 is the default condition FabDigit quotes; T7 is available on request or by drawing note.
Advantages
- High service temperature — 280°C (536 °F), better than 99% of aluminum grades
- Stiff — 82 GPa (11.9 Msi), better than 97% of aluminum grades
- Low embodied carbon — 10.5 kg CO₂/kg, better than 95% of aluminum grades
Limitations
- Limited formability — 4/100, worse than 99% of aluminum grades
- Limited ductility — 0.8%, worse than 97% of aluminum grades
- Difficult to machine — 30/100, worse than 92% of aluminum grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 89% of aluminum grades
- Low electrical conductivity — 27 % IACS, worse than 86% of aluminum grades
AC9B-T7 properties
Typical room-temperature values for AC9B-T7; 22 are specific to this condition. Other listed values are AC9B reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
AC9B-T7 has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 507°C (945 °F).
Mechanical13
AC9B-T7 has a yield strength of 165 MPa (23.9 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 58% of aluminum grades. Elongation at break is 0.8% and the elastic modulus is 82 GPa (11.9 Msi).
Thermal6
AC9B-T7 is rated for continuous service to 280°C (536 °F). It conducts heat at 138 W/m·K (79.7 BTU/hr·ft·°F), worse than 55% of aluminum grades. Thermal expansion is 17.8 µm/m·K (9.89 µin/in·°F).
Electrical3
AC9B-T7 conducts electricity at 27 % IACS, worse than 86% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 56% of aluminum grades.
Sustainability4
Producing a kilogram of AC9B-T7 takes about 155 MJ of energy and emits 10.5 kg of CO₂ — less than 94% of aluminum grades. Typical recycled content is 55%.
Manufacturability8
AC9B-T7's machinability is poor (30/100, worse than 92% of aluminum grades); weldability poor (24/100); formability not recommended (4/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AC9B-T7
Is AC9B easy to machine?
Highly abrasive primary silicon — use PCD or diamond-coated tooling, high speed / light feed with flood coolant; carbide life is very short.
Can AC9B be welded?
Poor fusion weldability (hot cracking, porosity, Cu pickup); repair only with 4047/4145-type filler and preheat, avoid on load-bearing sections.
Can AC9B be formed, bent or molded?
Permanent-mold/gravity or squeeze cast at 730–780 °C with phosphorus modification and controlled cooling to keep primary Si fine and evenly distributed.
What surface finishes work on AC9B?
Hard anodizing or ferrous/tin coatings on ring grooves and skirts for wear; decorative anodizing looks dark and mottled, so painting or shot-blast finishes are usual.
AC9B 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; refined with P (AlP nuclei) | 18 – 20 | 19 |
| Cu | 0.5 – 1.5 | 1 |
| Mg | 0.5 – 1.5 | 1 |
| Nihigh-temperature strength | 0.5 – 1.5 | 1 |
| Feimpurity limit | ≤ 0.8 | 0.5 |
| Mnimpurity limit | ≤ 0.5 | — |
| Znimpurity limit | ≤ 0.2 | — |
| Tiimpurity limit | ≤ 0.2 | — |
| Crimpurity limit | ≤ 0.1 | — |
| Pbimpurity limit | ≤ 0.05 | — |
| Snimpurity limit | ≤ 0.05 | — |
| Al | balance | — |
AC9B-T7 — frequently asked
What is AC9B-T7 used for?
AC9B-T7 is typically used for high-performance pistons, cylinder liners, wear-resistant sleeves, compressor pistons, pump and valve wear plates and high-temperature engine wear parts. In short: hardest AC casting alloy; hypereutectic liner grade; diamond tooling required.
What is the yield strength of AC9B-T7?
AC9B-T7 has a typical yield strength of 165 MPa (23.9 ksi) and a tensile strength of 185 MPa (26.8 ksi) — weaker than 58% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC9B-T7 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 92% of aluminum grades). Highly abrasive primary silicon — use PCD or diamond-coated tooling, high speed / light feed with flood coolant; carbide life is very short.
Can AC9B-T7 be welded?
Not readily — weldability is rated poor (24/100). Poor fusion weldability (hot cracking, porosity, Cu pickup); repair only with 4047/4145-type filler and preheat, avoid on load-bearing sections.
What surface finishes work on AC9B-T7?
Hard anodizing or ferrous/tin coatings on ring grooves and skirts for wear; decorative anodizing looks dark and mottled, so painting or shot-blast finishes are usual.
Can AC9B-T7 be formed, bent or molded?
Permanent-mold/gravity or squeeze cast at 730–780 °C with phosphorus modification and controlled cooling to keep primary Si fine and evenly distributed.
What is the maximum service temperature of AC9B-T7?
AC9B-T7 is rated for continuous use to about 280°C (536 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC9B-T6 and AC9B-F?
T6 is the default condition — standard condition for maximum strength and hardness in pistons and wear parts operating up to about 250 °C. F: lowest-cost condition for non-critical wear castings where dimensional stabilization is not required. Yield strength is 200 MPa in T6 versus 150 MPa in F.
Sources
- JIS H5202 Aluminium alloy castings — JSA (2010)
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys (A390 hypereutectic Al-Si data) — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASTM B108 / Aluminum Association Pink Sheets (A390.0) — ASTM / The Aluminum Association (2019)
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.