Aluminum AC4A
JIS AC4A
AC4A is a JIS heat-treatable Al-Si-Mg casting alloy (AlSi9Mg, equivalent to ZL104, EN AC-43000 and 356.0) that combines high silicon castability with Mg-based age hardening.
Reference datasheet — AC4A 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
AC4A tempers and conditions
AC4A is supplied in 5 conditions, soft to hard. T6 is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Cheapest route for low-stress housings and covers where dimensional stability matters more than strength. | 90 | 170 | 4 | 58 HB | 40 % IACS |
Solution heat treated and naturally aged | Choose when maximum ductility and impact toughness are wanted with moderate strength. | 115 | 215 | 8 | 65 HB | 36 % IACS |
Cooled from hot working and artificially aged | Low-distortion strength boost without solution treatment; good for thin, dimension-critical castings. | 145 | 205 | 2.5 | 70 HB | 41 % IACS |
Solution heat treated and overaged (stabilized) | Pick for parts that run hot or must stay dimensionally stable after machining, accepting some strength loss. | 175 | 230 | 4 | 80 HB | 42 % IACS |
T6Default Solution heat treated and artificially aged | Default condition: highest strength and hardness for load-bearing engine, gearbox and structural castings. | 200 | 260 | 3 | 90 HB | 39 % IACS |
What is AC4A?
AC4A is a JIS heat-treatable Al-Si-Mg casting alloy (AlSi9Mg, equivalent to ZL104, EN AC-43000 and 356.0) that combines high silicon castability with Mg-based age hardening. It is used for general-purpose sand, permanent-mold and low-pressure castings such as engine housings and gearbox casings, reaching 200 MPa yield, 260 MPa tensile, 3 % elongation and 90 HB with 150 W/m·K conductivity. Service is limited to about 150 °C and machinability is modest (score 50) because of the abrasive eutectic silicon. Where more ductility is needed, AC4C or AC4CH is the nearest alternative. AC4A has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 557°C (1,035 °F). AC4A has a yield strength of 200 MPa (29 ksi) and a tensile strength of 260 MPa (37.7 ksi) — stronger than 53% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
What is AC4A used for?
- engine housings
- gearbox casings
- wheels
- structural castings
Advantages
- Low embodied carbon — 9.5 kg CO₂/kg, better than 97% of aluminum grades
Limitations
- Limited formability — 10/100, worse than 80% of aluminum grades
- Limited ductility — 3%, worse than 79% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
AC4A properties
Typical room-temperature values for AC4A-T6; bars are the position among aluminum grades.
Physical3
AC4A has a density of 2.68 g/cm³ (0.0968 lb/in³), lighter than 72% of aluminum grades. It melts at 557°C (1,035 °F).
Mechanical13
AC4A has a yield strength of 200 MPa (29 ksi) and a tensile strength of 260 MPa (37.7 ksi) — stronger than 53% of aluminum grades. Elongation at break is 3% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
AC4A is rated for continuous service to 150°C (302 °F). It conducts heat at 150 W/m·K (86.7 BTU/hr·ft·°F), better than 58% of aluminum grades. Thermal expansion is 21.5 µm/m·K (11.9 µin/in·°F).
Electrical3
AC4A conducts electricity at 39 % IACS, better than 65% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), better than 57% of aluminum grades.
Sustainability4
Producing a kilogram of AC4A takes about 155 MJ of energy and emits 9.5 kg of CO₂ — less than 94% of aluminum grades. Typical recycled content is 70%.
Manufacturability8
AC4A's machinability is fair (50/100, worse than 65% of aluminum grades); weldability good (65/100); formability not recommended (10/100).
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. AC4A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AC4A
Is AC4A easy to machine?
Machinable but abrasive — use PCD or polished-flute carbide, high speed with flood coolant or MQL to avoid built-up edge from the eutectic Si.
Can AC4A be welded?
TIG/MIG weldable with ER4043 or ER4047 filler; preheat 150 °C for thick sections and re-solution/age afterwards to restore T6 properties in the HAZ.
Can AC4A be formed, bent or molded?
Foundry alloy with excellent fluidity for sand, permanent-mold and low-pressure casting; degas and Sr-modify the melt, and use directional solidification to avoid shrinkage porosity.
AC4A 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 |
|---|---|---|
| Siprimary fluidity/strength former; Sr or Na modification usual | 8 – 10 | 9 |
| MgMg2Si precipitation hardening | 0.3 – 0.6 | 0.45 |
| Mnneutralises Fe needles | 0.3 – 0.6 | 0.45 |
| Feimpurity | ≤ 0.55 | 0.35 |
| Cuimpurity; limits corrosion resistance | ≤ 0.25 | 0.1 |
| Znimpurity | ≤ 0.25 | |
| Niimpurity | ≤ 0.1 | |
| Tigrain refiner (Al-Ti-B) | ≤ 0.2 | 0.1 |
| Snimpurity | ≤ 0.05 | |
| Pbimpurity | ≤ 0.1 | |
| Al | balance |
What surface finishes work on AC4A?
Hard anodize for wear (dark grey), chromate/Ti-Zr conversion coat plus powder paint for appearance; shot blasting or impregnation is common to seal microporosity before plating.
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 AC4A in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- ZL104AC-43000AlSi9Mg356.0
How much does AC4A cost?
AC4A 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.
AC4A — frequently asked
What is AC4A used for?
AC4A is typically used for engine housings, gearbox casings, wheels and structural castings. In short: general-purpose AC casting alloy; heat-treatable Al-Si-Mg; balanced strength and castability.
What is the yield strength of AC4A?
AC4A has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 260 MPa (37.7 ksi) — stronger than 53% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is AC4A easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 65% of aluminum grades). Machinable but abrasive — use PCD or polished-flute carbide, high speed with flood coolant or MQL to avoid built-up edge from the eutectic Si.
Can AC4A be welded?
Yes — weldability is rated good (65/100). TIG/MIG weldable with ER4043 or ER4047 filler; preheat 150 °C for thick sections and re-solution/age afterwards to restore T6 properties in the HAZ.
What surface finishes work on AC4A?
Hard anodize for wear (dark grey), chromate/Ti-Zr conversion coat plus powder paint for appearance; shot blasting or impregnation is common to seal microporosity before plating.
Can AC4A be formed, bent or molded?
Foundry alloy with excellent fluidity for sand, permanent-mold and low-pressure casting; degas and Sr-modify the melt, and use directional solidification to avoid shrinkage porosity.
What is the maximum service temperature of AC4A?
AC4A is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC4A-T6 and AC4A-F?
T6 is the default condition — default condition: highest strength and hardness for load-bearing engine, gearbox and structural castings. F: cheapest route for low-stress housings and covers where dimensional stability matters more than strength. Yield strength is 200 MPa in T6 versus 90 MPa in F.
How much does AC4A cost?
AC4A 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)
- GB/T 1173 (ZL104) — SAC (2013)
- EN 1706 Aluminium and aluminium alloys — Castings (EN AC-43000 AlSi10Mg) — CEN (2020)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.15 — Casting — ASM International (2008)
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.