Aluminum AC4A-T6
Temper · default condition
JIS AC4A
T6 = solution heat treated and artificially aged
Default condition: highest strength and hardness for load-bearing engine, gearbox and structural castings.
Values for the T6 condition
Other AC4A tempers and conditions
AC4A is listed in 5 conditions; see the grade overview at AC4A.
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 |
T6DefaultThis page 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-T6?
AC4A-T6 is AC4A in the T6 temper — default condition: highest strength and hardness for load-bearing engine, gearbox and structural castings. AC4A-T6 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). AC4A-T6 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).
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-T6 properties
Typical room-temperature values for AC4A-T6; 11 are specific to this condition. Other listed values are AC4A reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
AC4A-T6 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-T6 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-T6 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-T6 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-T6 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-T6'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. Confirm any required mill or lot documentation when quoting.
Working with AC4A-T6
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.
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.
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 | — |
AC4A-T6 — frequently asked
What is AC4A-T6 used for?
AC4A-T6 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-T6?
AC4A-T6 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-T6 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-T6 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-T6?
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-T6 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-T6?
AC4A-T6 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.