Aluminum AC5A
JIS AC5A
AC5A is a JIS Al-Cu-Ni-Mg 'Y-alloy' type casting grade (A242.0 / 242.0) in which Cu and Ni intermetallics hold strength at temperature.
Reference datasheet — AC5A 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
AC5A tempers and conditions
AC5A 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 hot parts or as an intermediate state before machining and ageing. | 130 | 175 | 1 | 75 HB | 33 % IACS |
Cooled from hot working and artificially aged | Simple ageing without solution treatment — dimensionally stable pistons where distortion from quenching must be avoided. | 190 | 215 | 1 | 95 HB | 34 % IACS |
Solution heat treated and overaged (stabilized) | Overaged for maximum dimensional and thermal stability plus better ductility, at some loss of room-temperature strength. | 205 | 245 | 1.5 | 95 HB | 36 % IACS |
T6Default Solution heat treated and artificially aged | Standard peak-strength condition for highly loaded pistons, cylinder heads and hot structural castings. | 255 | 295 | 1 | 105 HB | 30 % IACS |
What is AC5A?
AC5A is a JIS Al-Cu-Ni-Mg 'Y-alloy' type casting grade (A242.0 / 242.0) in which Cu and Ni intermetallics hold strength at temperature. It is used for pistons and hot engine parts, offering 255 MPa yield, 295 MPa tensile, 105 HB and a 220 °C maximum service temperature — the highest in the AC family — at 122 W/m·K. Elongation is only 1 % and corrosion resistance is low (score 30), and the high Cu makes it hot-crack prone in fusion welding. Where temperature capability is not the driver, AC4D or AC4C gives far better ductility and corrosion behaviour. AC5A has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 528°C (982 °F). AC5A has a yield strength of 255 MPa (37 ksi) and a tensile strength of 295 MPa (42.8 ksi) — stronger than 67% of aluminum grades. Elongation at break is 1% and the elastic modulus is 71 GPa (10.3 Msi).
What is AC5A used for?
- engine pistons
- cylinder heads
- high-temperature components
Advantages
- High service temperature — 220°C (428 °F), better than 95% of aluminum grades
- Low embodied carbon — 10.5 kg CO₂/kg, better than 95% of aluminum grades
- Easy to machine — 72/100, better than 80% of aluminum grades
Limitations
- Needs corrosion protection — 30/100, worse than 98% of aluminum grades
- Limited ductility — 1%, worse than 95% of aluminum grades
- Limited formability — 5/100, worse than 94% of aluminum grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 83% of aluminum grades
- Difficult to weld — 25/100, worse than 76% of aluminum grades
AC5A properties
Typical room-temperature values for AC5A-T6; bars are the position among aluminum grades.
Physical3
AC5A has a density of 2.81 g/cm³ (0.102 lb/in³), heavier than 86% of aluminum grades. It melts at 528°C (982 °F).
Mechanical14
AC5A has a yield strength of 255 MPa (37 ksi) and a tensile strength of 295 MPa (42.8 ksi) — stronger than 67% of aluminum grades. Elongation at break is 1% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
AC5A is rated for continuous service to 220°C (428 °F). It conducts heat at 122 W/m·K (70.5 BTU/hr·ft·°F), worse than 74% of aluminum grades. Thermal expansion is 22.5 µm/m·K (12.5 µin/in·°F).
Electrical3
AC5A conducts electricity at 30 % IACS, worse than 73% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is poor (30/100), worse than 98% of aluminum grades.
Sustainability4
Producing a kilogram of AC5A takes about 150 MJ of energy and emits 10.5 kg of CO₂ — less than 97% of aluminum grades. Typical recycled content is 35%.
Manufacturability8
AC5A's machinability is very good (72/100, better than 80% of aluminum grades); weldability poor (25/100); formability not recommended (5/100).
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. AC5A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AC5A
Is AC5A easy to machine?
Machines very well with carbide tooling and high speeds; the Cu/Ni intermetallics give short chips and good finish, but they are abrasive so PCD is preferred for high-volume piston skirt turning.
Can AC5A be welded?
Poor fusion weldability — high Cu content makes it hot-crack prone; repair only with 4145/2319 filler, preheat 150–200 °C and re-age afterwards.
Can AC5A be formed, bent or molded?
Gravity die (permanent mold) or sand cast with good feeding and chills; narrow freezing range is not favorable — expect hot tearing at section changes and design generous fillets.
AC5A 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 |
|---|---|---|
| Cu | 3.5 – 4.5 | 4 |
| Niprovides elevated-temperature strength | 1.7 – 2.3 | 2 |
| Mg | 1.2 – 1.8 | 1.5 |
| Si | ≤ 0.6 | 0.3 |
| Fe | ≤ 0.8 | 0.4 |
| Mn | ≤ 0.35 | |
| Zn | ≤ 0.15 | |
| Tigrain refiner | ≤ 0.2 | |
| Cr | ≤ 0.15 | |
| Sn | ≤ 0.05 | |
| Pb | ≤ 0.05 | |
| Al | balance |
What surface finishes work on AC5A?
Hard (Type III) anodize on crowns/ring grooves for wear and heat; decorative anodizing is dark and blotchy, so painting, Ni or ferrous ring-carrier inserts are used where appearance or corrosion matters.
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 AC5A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does AC5A cost?
AC5A is a premium-cost aluminum ($$$), cheaper than about 51% 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.
AC5A — frequently asked
What is AC5A used for?
AC5A is typically used for engine pistons, cylinder heads and high-temperature components. In short: highest service temperature, 220 °C; classic piston casting alloy; low ductility and corrosion resistance.
What is the yield strength of AC5A?
AC5A has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 295 MPa (42.8 ksi) — stronger than 67% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC5A easy to machine?
Yes — machinability is rated very good (72/100, better than 80% of aluminum grades). Machines very well with carbide tooling and high speeds; the Cu/Ni intermetallics give short chips and good finish, but they are abrasive so PCD is preferred for high-volume piston skirt turning.
Can AC5A be welded?
Not readily — weldability is rated poor (25/100). Poor fusion weldability — high Cu content makes it hot-crack prone; repair only with 4145/2319 filler, preheat 150–200 °C and re-age afterwards.
What surface finishes work on AC5A?
Hard (Type III) anodize on crowns/ring grooves for wear and heat; decorative anodizing is dark and blotchy, so painting, Ni or ferrous ring-carrier inserts are used where appearance or corrosion matters.
Can AC5A be formed, bent or molded?
Gravity die (permanent mold) or sand cast with good feeding and chills; narrow freezing range is not favorable — expect hot tearing at section changes and design generous fillets.
What is the maximum service temperature of AC5A?
AC5A is rated for continuous use to about 220°C (428 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC5A-T6 and AC5A-F?
T6 is the default condition — standard peak-strength condition for highly loaded pistons, cylinder heads and hot structural castings. F: lowest-cost condition for non-critical hot parts or as an intermediate state before machining and ageing. Yield strength is 255 MPa in T6 versus 130 MPa in F.
How much does AC5A cost?
AC5A is a premium-cost aluminum ($$$), cheaper than about 51% 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 H 5202 Aluminium alloy castings — JSA (2010)
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys (Alloy 242.0) — ASM International (1990)
- ASM Specialty Handbook: Aluminum and Aluminum Alloys — ASM International (1993)
- ASTM B26/B26M and B108/B108M (242.0 castings) — ASTM (2018)
- Aluminum Association Registration Record (Pink Sheets) — cast alloy 242.0 — The Aluminum Association (2018)
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.