Aluminum AlSi9Cu3-T6
Temper
EN AlSi9Cu3
T6 = solution heat treated and artificially aged
Maximum strength for gravity/vacuum-assist castings only — conventional HPDC parts blister during the ~490 °C solution soak.
Values for the T6 condition
Other AlSi9Cu3 tempers and conditions
AlSi9Cu3 is listed in 5 conditions; see the grade overview at AlSi9Cu3.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
F | Choose for larger, thicker gravity-cast parts where die casting is impractical; coarser structure, lower strength. | 110 | 200 | 1.5 | 80 HB | 25 % IACS |
FDefault As fabricated | Standard supply condition: high-pressure die castings used as-cast, best strength/cost balance. | 165 | 300 | 2 | 85 HB | 24 % IACS |
Solution heat treated and overaged (stabilized) | Pick when dimensional stability and elevated-temperature service matter more than peak strength. | 200 | 280 | 2.5 | 95 HB | 30 % IACS |
Cooled from hot working and artificially aged | Low-cost ageing (~200-230 °C) of die castings to raise yield strength and dimensional stability without blistering risk. | 210 | 320 | 1.5 | 95 HB | 26 % IACS |
T6This page Solution heat treated and artificially aged | Maximum strength for gravity/vacuum-assist castings only — conventional HPDC parts blister during the ~490 °C solution soak. | 250 | 330 | 1.5 | 110 HB | 25 % IACS |
What is AlSi9Cu3-T6?
AlSi9Cu3-T6 is AlSi9Cu3 in the T6 temper — maximum strength for gravity/vacuum-assist castings only — conventional HPDC parts blister during the ~490 °C solution soak. AlSi9Cu3-T6 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 65% of aluminum grades. Elongation at break is 1.5% and the elastic modulus is 75 GPa (10.9 Msi). AlSi9Cu3-T6 has a density of 2.75 g/cm³ (0.0994 lb/in³), heavier than 67% of aluminum grades. It melts at 515°C (959 °F). F is the default condition FabDigit quotes; T6 is available on request or by drawing note.
Advantages
- High service temperature — 175°C (347 °F), better than 83% of aluminum grades
Limitations
- Low electrical conductivity — 25 % IACS, worse than 92% of aluminum grades
- Limited ductility — 1.5%, worse than 91% of aluminum grades
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 89% of aluminum grades
- Difficult to weld — 20/100, worse than 89% of aluminum grades
AlSi9Cu3-T6 properties
Typical room-temperature values for AlSi9Cu3-T6; 10 are specific to this condition. Other listed values are AlSi9Cu3 reference data and may not represent this condition. Bars are the position among aluminum grades.
Physical3
AlSi9Cu3-T6 has a density of 2.75 g/cm³ (0.0994 lb/in³), heavier than 67% of aluminum grades. It melts at 515°C (959 °F).
Mechanical13
AlSi9Cu3-T6 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 65% of aluminum grades. Elongation at break is 1.5% and the elastic modulus is 75 GPa (10.9 Msi).
Thermal6
AlSi9Cu3-T6 is rated for continuous service to 175°C (347 °F). It conducts heat at 118 W/m·K (68.2 BTU/hr·ft·°F), worse than 81% of aluminum grades. Thermal expansion is 21 µm/m·K (11.7 µin/in·°F).
Electrical3
AlSi9Cu3-T6 conducts electricity at 25 % IACS, worse than 92% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 79% of aluminum grades.
Sustainability4
Producing a kilogram of AlSi9Cu3-T6 takes about 190 MJ of energy and emits 12.5 kg of CO₂ — less than 89% of aluminum grades. Typical recycled content is 85%.
Manufacturability8
AlSi9Cu3-T6's machinability is good (68/100, better than 67% of aluminum grades); weldability poor (20/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AlSi9Cu3-T6
Is AlSi9Cu3 easy to machine?
Machines well for a casting alloy — Cu gives short chips, but primary/eutectic Si is abrasive, so use PCD or polished-flute carbide, high speed, low feed and flood or MQL cooling.
Can AlSi9Cu3 be welded?
Poor fusion weldability: 2-4 % Cu promotes hot cracking and die-cast gas porosity blisters; join by mechanical fastening, adhesive or self-pierce riveting, or use friction stir/laser welding on vacuum-cast and LPBF material with 4047 filler.
Can AlSi9Cu3 be formed, bent or molded?
Outstanding die-casting fluidity, low shrinkage and low die soldering with 0.8-1.1 % Fe; in LPBF it prints readily at ~350-400 W with 60-80 µm layers but needs preheated plate (150-200 °C) and reflective-powder-tolerant optics.
What surface finishes work on AlSi9Cu3?
Do not decorative-anodize (dark, patchy film from Si+Cu); use chromate-free conversion coating, powder coat, e-coat or hard anodize for wear; shot blasting and vibratory finishing work well, mirror polishing is limited by Si particles.
AlSi9Cu3 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 |
|---|---|---|
| SiEN AC-46000 AlSi9Cu3(Fe) | 8 – 11 | 9.5 |
| Cu | 2 – 4 | 3 |
| Fe0.6-1.1 % preferred for die-soldering control | ≤ 1.3 | 0.9 |
| Mn | ≤ 0.55 | 0.25 |
| Mg | 0.05 – 0.55 | 0.25 |
| Zn | ≤ 1.2 | 0.6 |
| Ni | ≤ 0.55 | 0.1 |
| Cr | ≤ 0.15 | — |
| Ti | ≤ 0.25 | 0.1 |
| Pb0.25 max in ELV/RoHS-compliant variants | ≤ 0.35 | — |
| Sn | ≤ 0.25 | — |
| Others (each) | ≤ 0.05 | — |
| Others (total) | ≤ 0.25 | — |
| Al | balance | — |
AlSi9Cu3-T6 — frequently asked
What is AlSi9Cu3-T6 used for?
AlSi9Cu3-T6 is typically used for housings, low-cost prototypes, automotive components and general industrial brackets. In short: best-machining Al-Si casting alloy; low-cost LPBF aluminum; poor fusion weldability.
What is the yield strength of AlSi9Cu3-T6?
AlSi9Cu3-T6 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 65% of aluminum grades. Strength varies by condition: see the 5 listed tempers.
Is AlSi9Cu3-T6 easy to machine?
Reasonably — machinability is rated good (68/100, better than 67% of aluminum grades). Machines well for a casting alloy — Cu gives short chips, but primary/eutectic Si is abrasive, so use PCD or polished-flute carbide, high speed, low feed and flood or MQL cooling.
Can AlSi9Cu3-T6 be welded?
Not readily — weldability is rated poor (20/100). Poor fusion weldability: 2-4 % Cu promotes hot cracking and die-cast gas porosity blisters; join by mechanical fastening, adhesive or self-pierce riveting, or use friction stir/laser welding on vacuum-cast and LPBF material with 4047 filler.
What surface finishes work on AlSi9Cu3-T6?
Do not decorative-anodize (dark, patchy film from Si+Cu); use chromate-free conversion coating, powder coat, e-coat or hard anodize for wear; shot blasting and vibratory finishing work well, mirror polishing is limited by Si particles.
Can AlSi9Cu3-T6 be formed, bent or molded?
Outstanding die-casting fluidity, low shrinkage and low die soldering with 0.8-1.1 % Fe; in LPBF it prints readily at ~350-400 W with 60-80 µm layers but needs preheated plate (150-200 °C) and reflective-powder-tolerant optics.
What is the maximum service temperature of AlSi9Cu3-T6?
AlSi9Cu3-T6 is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AlSi9Cu3-F and AlSi9Cu3-T6?
F is the default condition — standard supply condition: high-pressure die castings used as-cast, best strength/cost balance. T6: maximum strength for gravity/vacuum-assist castings only — conventional HPDC parts blister during the ~490 °C solution soak. Yield strength is 165 MPa in F versus 250 MPa in T6.
Sources
- EN 1706 — Aluminium and aluminium alloys: Castings, chemical composition and mechanical properties (EN AC-46000) — CEN (2020)
- EN 1676 — Aluminium alloy ingots for remelting — CEN (2020)
- JIS H 5302 (ADC12) / ASTM B85 (A380.0) equivalents — JSA / ASTM (2021)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- ASM Handbook Vol.15 — Casting — ASM International (2008)
- Al-Si-Cu die-casting and LPBF powder datasheets — Rheinfelden Alloys / ECKA Granules / SLM producers (2023)
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.