Aluminum AC9B
JIS AC9B
AC9B is a JIS hypereutectic Al-Si piston alloy (A390.0) with the Cu/Ni/Mg balance shifted relative to AC9A to tune mechanical properties.
Reference datasheet — AC9B is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the T6 condition
AC9B tempers and conditions
AC9B is supplied in 4 conditions, soft to hard. T6 is the default FabDigit quotes; the values on this page are for it.
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 |
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?
AC9B is a JIS hypereutectic Al-Si piston alloy (A390.0) with the Cu/Ni/Mg balance shifted relative to AC9A to tune mechanical properties. It provides 220 MPa tensile, 200 MPa yield, 140 HB, 130 W/m·K, 25% IACS and a 250 °C service limit, cast by permanent-mould, gravity or squeeze casting and supplied in F, T5, T6 and T7. Machinability of 28 and 0.5% elongation are the limits: PCD tooling is needed, the alloy is brittle, and fusion welding is repair-only because of hot cracking and porosity. AC8A is the option where machining cost matters more than wear resistance. AC9B 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). AC9B has a yield strength of 200 MPa (29 ksi) and a tensile strength of 220 MPa (31.9 ksi) — stronger than 53% of aluminum grades. Elongation at break is 0.5% and the elastic modulus is 82 GPa (11.9 Msi).
What is AC9B used for?
- High-performance pistons
- Cylinder liners
- Wear-resistant sleeves
- Compressor pistons
- Pump and valve wear plates
- High-temperature engine wear parts
Advantages
- Stiff — 82 GPa (11.9 Msi), better than 97% 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 formability — 3/100, worse than 100% of aluminum grades
- Limited ductility — 0.5%, worse than 99% of aluminum grades
- Difficult to machine — 28/100, worse than 94% of aluminum grades
- Low fracture toughness — 15 MPa·√m (13.7 ksi·√in), worse than 93% of aluminum grades
- Low electrical conductivity — 25 % IACS, worse than 92% of aluminum grades
AC9B properties
Typical room-temperature values for AC9B-T6; bars are the position among aluminum grades.
Physical3
AC9B 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 has a yield strength of 200 MPa (29 ksi) and a tensile strength of 220 MPa (31.9 ksi) — stronger than 53% of aluminum grades. Elongation at break is 0.5% and the elastic modulus is 82 GPa (11.9 Msi).
Thermal6
AC9B is rated for continuous service to 250°C (482 °F). It conducts heat at 130 W/m·K (75.1 BTU/hr·ft·°F), worse than 65% of aluminum grades. Thermal expansion is 17.8 µm/m·K (9.89 µin/in·°F).
Electrical3
AC9B conducts electricity at 25 % IACS, worse than 92% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (48/100), worse than 58% of aluminum grades.
Sustainability4
Producing a kilogram of AC9B 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's machinability is poor (28/100, worse than 94% of aluminum grades); weldability poor (22/100); formability not recommended (3/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the aluminum family
Yield strength against density for every aluminum grade FabDigit runs. AC9B is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AC9B
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.
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 |
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.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Aluminum AC9B in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- A390.0
How much does AC9B cost?
AC9B is a standard-cost aluminum ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
AC9B — frequently asked
What is AC9B used for?
AC9B 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?
AC9B has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 220 MPa (31.9 ksi) — stronger than 53% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC9B easy to machine?
Not especially — machinability is rated poor (28/100, worse than 94% 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 be welded?
Not readily — weldability is rated poor (22/100). 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?
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 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?
AC9B 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 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.
How much does AC9B cost?
AC9B is a standard-cost aluminum ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.