Aluminum AlSi12 · heat-treated state
Aluminum AlSi12 Stress Relieved
Properties of the Stress Relieved condition, compared with the other AlSi12 tempers.
Standard choice for dimensionally stable parts: removes build residual stress and raises ductility and conductivity at the cost of ~25 % strength.
What is AlSi12 Stress Relieved?
AlSi12 Stress Relieved is AlSi12 heat treated to Stress Relieved — standard choice for dimensionally stable parts: removes build residual stress and raises ductility and conductivity at the cost of ~25 % strength. AlSi12 Stress Relieved has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 54% of aluminum grades. Elongation at break is 9% and the elastic modulus is 72 GPa (10.4 Msi). AlSi12 Stress Relieved has a density of 2.67 g/cm³ (0.0965 lb/in³), lighter than 78% of aluminum grades. It melts at 574°C (1,065 °F). As Printed is the default condition FabDigit quotes; Stress Relieved is available on request or by drawing note.
Limitations
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 83% of aluminum grades
AlSi12 Stress Relieved properties
Typical room-temperature values for AlSi12 Stress Relieved — 12 properties are specific to this condition; the rest are grade-level values shared by every AlSi12 temper. Each bar shows where the value sits among the aluminum grades in FabDigit's library — further right is higher.
Physical3
AlSi12 Stress Relieved has a density of 2.67 g/cm³ (0.0965 lb/in³), lighter than 78% of aluminum grades. It melts at 574°C (1,065 °F).
Mechanical14
AlSi12 Stress Relieved has a yield strength of 180 MPa (26.1 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 54% of aluminum grades. Elongation at break is 9% and the elastic modulus is 72 GPa (10.4 Msi).
Thermal6
AlSi12 Stress Relieved is rated for continuous service to 150°C (302 °F). It conducts heat at 145 W/m·K (83.8 BTU/hr·ft·°F), better than 53% of aluminum grades. Thermal expansion is 20.4 µm/m·K (11.3 µin/in·°F).
Electrical3
AlSi12 Stress Relieved conducts electricity at 33 % IACS, worse than 57% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 51% of aluminum grades.
Sustainability4
Producing a kilogram of AlSi12 Stress Relieved takes about 215 MJ of energy and emits 13 kg of CO₂ — more than 92% of aluminum grades. Typical recycled content is 10%.
Manufacturability7
AlSi12 Stress Relieved's machinability is good (58/100, worse than 53% of aluminum grades); weldability very good (80/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other AlSi12 tempers and conditions
AlSi12 is also supplied in 3 other conditions. The full side-by-side table is on the AlSi12 overview.
- As PrintedDefaultHighest strength and hardness from the ultrafine cellular Si network; use when residual stress and distortion are tolerable.250 MPa yield · 105 HB
- Stress RelievedStandard choice for dimensionally stable parts: removes build residual stress and raises ductility and conductivity at the cost of ~25 % strength.180 MPa yield · 78 HB
- T6Applied when maximum ductility and stability are wanted; because AlSi12 has essentially no Mg or Cu the age-hardening response is small and strength stays below the as-printed level.150 MPa yield · 70 HB
- HIPCloses gas and lack-of-fusion porosity for fatigue-critical or pressure-tight parts; strength drops sharply because the Si network spheroidises.130 MPa yield · 63 HB
Working with AlSi12 Stress Relieved
Is AlSi12 easy to machine?
Machine with polished-flute uncoated or diamond-coated carbide, high speed and copious coolant; the eutectic Si is abrasive and chips are gummy without sharp edges.
Can AlSi12 be welded?
Excellent — the alloy is essentially 4047 filler chemistry, so TIG/laser repair welding of printed parts is straightforward with little hot-cracking risk.
Can AlSi12 be formed, bent or molded?
Not a wrought alloy: parts are built by LPBF (or cast); design for self-supporting angles, keep walls ≥0.4 mm, and stress-relieve before removing from the plate to avoid distortion.
What surface finishes work on AlSi12?
Blast, tumble or machine to remove partially melted particles; hard anodising is possible but the high Si gives a dark grey, patchy colour, so paint, powder coat or chemical conversion coating is preferred for cosmetics.
AlSi12 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 |
|---|---|---|
| Sinear-eutectic; AM powders typically 11–13 | 10.5 – 13.5 | 12 |
| Fe | ≤ 0.55 | 0.2 |
| Cu | ≤ 0.1 | 0.02 |
| Mn | ≤ 0.45 | 0.05 |
| Mgmax; no deliberate Mg, hence weak T6 response | ≤ 0.1 | 0.02 |
| Zn | ≤ 0.15 | 0.03 |
| Ti | ≤ 0.15 | 0.03 |
| Ni | ≤ 0.05 | — |
| Pb | ≤ 0.05 | — |
| Sn | ≤ 0.05 | — |
| Others (each / total)0.05 each, 0.15 total | ≤ 0.15 | — |
| Al | balance | — |
AlSi12 Stress Relieved — frequently asked
What is AlSi12 Stress Relieved used for?
AlSi12 Stress Relieved is typically used for heat sinks and cold plates, thin-wall housings and enclosures, fluid and air manifolds, electronics and RF housings, lightweight brackets and mounts and jigs, fixtures and tooling inserts. In short: eutectic Al-Si AM powder; excellent castability.
What is the yield strength of AlSi12 Stress Relieved?
AlSi12 Stress Relieved has a typical yield strength of 180 MPa (26.1 ksi) and a tensile strength of 300 MPa (43.5 ksi) — weaker than 54% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AlSi12 Stress Relieved easy to machine?
Reasonably — machinability is rated good (58/100, worse than 53% of aluminum grades). Machine with polished-flute uncoated or diamond-coated carbide, high speed and copious coolant; the eutectic Si is abrasive and chips are gummy without sharp edges.
Can AlSi12 Stress Relieved be welded?
Yes — weldability is rated very good (80/100). Excellent — the alloy is essentially 4047 filler chemistry, so TIG/laser repair welding of printed parts is straightforward with little hot-cracking risk.
What surface finishes work on AlSi12 Stress Relieved?
Blast, tumble or machine to remove partially melted particles; hard anodising is possible but the high Si gives a dark grey, patchy colour, so paint, powder coat or chemical conversion coating is preferred for cosmetics.
Can AlSi12 Stress Relieved be formed, bent or molded?
Not a wrought alloy: parts are built by LPBF (or cast); design for self-supporting angles, keep walls ≥0.4 mm, and stress-relieve before removing from the plate to avoid distortion.
What is the maximum service temperature of AlSi12 Stress Relieved?
AlSi12 Stress Relieved 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 AlSi12 As Printed and AlSi12-HIP?
As Printed is the default condition — highest strength and hardness from the ultrafine cellular Si network; use when residual stress and distortion are tolerable. HIP: closes gas and lack-of-fusion porosity for fatigue-critical or pressure-tight parts; strength drops sharply because the Si network spheroidises. Yield strength is 250 MPa in As Printed versus 130 MPa in HIP.
Can FabDigit make parts in AlSi12 Stress Relieved?
Yes — AlSi12 Stress Relieved is available for 3D printing with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 1706 — Aluminium and aluminium alloys, castings (EN AC-44200) — CEN (2020)
- ASTM B108 / Aluminum Association designation A413.0 — ASTM / Aluminum Association (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- EOS Aluminium AlSi12 material data sheet — EOS GmbH (2022)
- SLM Solutions / Nikon SLM Al-Alloy AlSi12 powder data sheet — SLM Solutions (2021)
- Published LPBF AlSi12 mechanical and thermophysical property studies — peer-reviewed AM literature (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.