AlSi10Mg is an aluminum alloy with about 9–11% silicon and 0.2–0.45% magnesium. Originally a casting alloy (EN AC-43000 under EN 1706), it is the most widely used aluminum for laser powder bed fusion (DMLS and SLM). Its near-eutectic composition melts and solidifies over a narrow temperature range, so it prints with little tendency to crack. Rapid cooling in the melt pool produces a very fine microstructure: printed parts are stronger than castings of the same alloy, at about one-third the density of steel.
Choose AlSi10Mg for light, complex parts that are difficult or impossible to machine or cast: heat exchangers, manifolds with internal channels, topology-optimized brackets and lattice structures. It is offered through Uretyco's manufacturing partners as a DMLS material. Its limits are lower ductility and fatigue strength than wrought aluminum, direction-dependent properties, a rough as-built surface and strength that falls above about 150 °C. For simple shapes, machined 6061-T6 is usually cheaper, faster and more precise.
Mechanical and physical properties
| Property | Typical value | Notes |
|---|---|---|
| Tensile strength (Rm) | ≈ 350–470 MPa | As built, in the build plane (XY). Falls to ≈ 300–350 MPa after stress relief; a T6-type treatment gives similar or slightly lower values. |
| Yield strength (Rp0.2) | ≈ 220–290 MPa | As built. ≈ 180–230 MPa after stress relief, compared with ≈ 276 MPa for wrought 6061-T6. |
| Elongation at break | ≈ 3–9% | As built; lowest in the build direction (Z). Rises to ≈ 8–15% after stress relief. |
| Hardness | ≈ 100–130 HB | As built; heat treatment lowers it. |
| Elastic modulus | ≈ 65–75 GPa | Similar to other aluminum alloys. |
| Density | ≈ 2.67 g/cm³ | Printed parts typically reach more than 99.5% of full density. |
| Thermal conductivity | ≈ 100–130 W/m·K | As built; rises to ≈ 150–175 W/m·K after heat treatment, which matters for heat exchangers. |
| Thermal expansion | ≈ 20–22 µm/m·K | 20–100 °C; similar to cast aluminum-silicon alloys. |
| Service temperature | Up to ≈ 150 °C under load | Aluminum alloys lose strength quickly above this range; check the data for load-bearing parts. |
| As-built surface roughness | ≈ Ra 6–15 µm | Upward-facing and vertical faces; downward-facing and supported faces are rougher. |
| Fatigue strength | Strongly condition-dependent | As-built surfaces and porosity reduce fatigue life sharply; machining, polishing and HIP improve it. |
Ranges combine published data for laser powder bed fused AlSi10Mg measured on test specimens. Real parts vary with machine, process parameters, powder, build orientation, wall thickness and heat treatment. For load-bearing parts, design to the data sheet named in the quote, a specification such as ASTM F3318 where it applies, and tests on specimens built together with the parts.
Designing AlSi10Mg parts for DMLS and SLM
In laser powder bed fusion, a laser melts the powder layer by layer in an argon atmosphere, typically 30–60 µm per layer. Parts are anchored to a build plate by supports that also conduct heat away, so support strategy and orientation decide cost, distortion and surface quality. General rules, confirmed in the quote:
- Overhangs and supports: faces flatter than about 45° to the build plate need supports. Supports are removed by cutting, sawing or machining and leave witness marks, so keep functional and visible faces free of them where possible.
- Holes and channels: horizontal holes and channels up to about 6–8 mm in diameter usually print without internal supports. Larger ones need supports, which are hard to remove inside a channel, or a self-supporting teardrop or diamond profile.
- Walls and details: walls down to about 0.5 mm can be printed, but 1 mm or more is more robust and easier to finish. Thin, tall features can be damaged by the recoater during the build.
- Residual stress: large flat areas and abrupt changes from thin to thick sections distort. Use ribs, fillets and gradual transitions instead of solid blocks; parts are usually stress-relieved on the build plate before removal.
- Powder removal: every internal cavity needs openings to remove unfused powder, because closed voids keep it inside. Plan at least two openings for long channels and check that they can be flushed.
- Machining stock and orientation: leave about 0.5–1 mm of stock on faces, bores and threads that will be machined, and state the main load direction. Elongation is lowest across the layers, so keep the main load path in the build plane where possible.
Heat treatment: as built, stress relieved or T6-type
Heat treatment changes AlSi10Mg more than most printed alloys: it trades part of the high as-built strength for ductility, dimensional stability and conductivity. Specify the condition explicitly, because suppliers use different default routes.
| Condition | Typical treatment | Effect | Use when |
|---|---|---|---|
| As built | None | Highest strength and hardness, lowest ductility; residual stresses remain | Compact, stiff parts and prototypes, if the supplier accepts it |
| Stress relieved | ≈ 300 °C for about 2 h, often on the build plate | Rm ≈ 300–350 MPa, higher elongation, less distortion during machining, higher conductivity | The usual default for functional parts |
| T6-type | Solution treatment at ≈ 520–540 °C, quenching, artificial aging at ≈ 160–180 °C | More uniform, less direction-dependent properties with good ductility; quenching can distort thin parts | Parts that need ductility and consistent properties and are machined after heat treatment |
| HIP | Hot isostatic pressing, usually followed by heat treatment | Closes internal porosity and improves fatigue life | Fatigue-critical or pressure-tight parts |
Tolerances and surface
Printed accuracy depends on part size, orientation, supports and distortion. As a planning guide, small features typically hold about ±0.1–0.2 mm, with larger deviations on long or flat parts; final values are confirmed in the quote and order review. Fits, sealing faces and threads are machined after printing and can be toleranced like CNC parts, where Uretyco's default for unspecified tolerances is ISO 2768-mK. As-built surfaces are matte and slightly grainy; state Ra only on faces that will be machined or polished.
Finishing options
Bead blasting after support removal is the standard finish. Further steps are functional or cosmetic and are added in the quote.
| Finish | Effect | Notes |
|---|---|---|
| Bead blasting | Uniform matte surface | Removes loose powder and smooths the surface slightly; the usual base finish. |
| CNC machining | Precise fits, sealing faces and threads | Needs machining stock and clamping features; mark machined faces on the drawing. |
| Vibratory finishing | Smoother surfaces and rounded edges | Suits small parts; does not reach deep internal channels. |
| Shot peening | Compressive stress at the surface | Improves fatigue life; specify the intensity for critical parts. |
| Anodizing | Corrosion and wear protection | The high silicon content gives a gray, uneven appearance; protective rather than decorative. |
| Conversion coating, paint or powder coat | Corrosion protection and color | Paint and powder coat give the most even color on printed aluminum. |
When printed parts are finish-machined, add reference faces and clamping features to the model and state which faces stay as printed. This saves setups and prevents thin printed walls from being machined away.
Cost and lead-time drivers
Metal printing is priced mainly by machine time and post-processing rather than by powder. The main levers:
- Build height and machine time: every layer takes time, so tall parts cost more than flat parts of the same volume. Several parts can share one build plate.
- Melted volume: solid blocks are expensive; shelling, lattices and topology optimization reduce volume and weight.
- Supports: support structures consume machine time and powder, and removing them is manual work. A good orientation and self-supporting features reduce both.
- Post-processing: stress relief, T6-type treatment, HIP, machining and finishing are separate steps, each adding cost and lead time.
- Documents and review: material certificates and measurement reports are opt-in and should be requested at quote time; feasibility, orientation and lead time are confirmed in the quote and order review.
AlSi10Mg vs. common alternatives
| Material and process | Strength (Rm) | Elongation | Density | Relative cost | Best for |
|---|---|---|---|---|---|
| AlSi10Mg, printed (DMLS, SLM) | ≈ 300–470 MPa | ≈ 3–15% | ≈ 2.67 g/cm³ | High | Complex, light parts with internal channels or lattices |
| Aluminum 6061-T6, machined | ≈ 310 MPa | ≈ 12–17% | 2.70 g/cm³ | Low to medium | Precise prismatic parts, anodized finishes |
| Aluminum A356-T6, cast | ≈ 250–280 MPa | ≈ 3–10% | 2.68 g/cm³ | Low at volume; needs tooling | Repeat housings and structural castings |
| Ti-6Al-4V, printed | ≈ 900–1100 MPa | ≈ 6–15% | 4.43 g/cm³ | Very high | Highly loaded, hot or corrosive parts |
If a part can be machined from plate or bar, 6061-T6 usually costs less, gives better surfaces and tighter tolerances, and anodizes evenly. Cast A356 becomes cheaper once quantities pay for a pattern or mold. Ti-6Al-4V offers more than twice the strength at about 1.7 times the density and suits loads, temperatures or environments where aluminum is not enough.
When not to choose AlSi10Mg
Simple parts that machine easily from 6061 or 7075: machining is cheaper, faster and more precise. Larger quantities of the same part: casting or die casting costs less per part. Decorative anodized surfaces. Continuous load above about 150 °C: consider titanium or steel. Fatigue-critical parts without machined or polished surfaces, HIP and a test plan. Parts larger than the partner's build envelope, unless they can be split and joined.
Typical applications
- Heat exchangers, cold plates and housings with integrated cooling channels.
- Hydraulic and pneumatic manifolds with internal passages.
- Topology-optimized brackets and lightweight lattice structures.
- Prototypes and small series for motorsport, drones and aerospace.
- Functional prototypes of future cast or die-cast aluminum parts.
- Lightweight grippers and end-of-arm tooling for robots.
Specifying AlSi10Mg on Uretyco
- 1Upload the model and a drawing
STEP is preferred for metal parts; STL or 3MF also work. Add a PDF drawing for machined faces, threads, tolerances and inspection requirements.
- 2Choose DMLS and AlSi10Mg
Select the layer thickness setting: thicker layers build faster, thinner layers give finer detail. Leave the choice between DMLS and SLM machines open unless your specification fixes it.
- 3State the condition
As built, stress relieved or T6-type, plus HIP if required. Name the specification or data sheet if your design depends on it.
- 4Mark critical faces and orientation
Show faces that must stay free of supports, faces to be machined with their allowance, and the main load direction.
- 5Choose finishing and documents
Bead blasting, machining, anodizing or paint; request material certificates and measurement reports at quote time.
- 6Review the quote
Feasibility, orientation, heat treatment and lead time are confirmed in the quote and order review before production starts.
FAQ
Is there a difference between DMLS and SLM?
Both names describe laser powder bed fusion, which ISO/ASTM 52900 classifies as powder bed fusion. Although DMLS has sintering in its name, the metal is fully melted in both. Results depend far more on the machine, the process parameters and the heat treatment than on the name.
Is printed AlSi10Mg as strong as 6061-T6?
As built, its tensile strength exceeds that of 6061-T6, but its elongation and fatigue strength are lower. After stress relief, its yield strength falls below that of 6061-T6. A design made for machined 6061 therefore cannot simply be switched to printing; check the condition, the load direction and the surfaces.
Which heat treatment should I specify?
Stress relief is the usual default for functional parts. Choose as built only for compact prototypes where maximum strength matters and residual stress is acceptable, and a T6-type treatment when ductility and uniform properties matter more than peak strength. Add HIP for fatigue-critical or pressure-tight parts.
Can printed AlSi10Mg be anodized?
Yes, but the high silicon content produces a gray, sometimes blotchy layer, and colors look muted. Anodizing works well as protection; for an even cosmetic color, use paint or powder coat, or have the part machined from 6061.
Related resources
- Aluminum 6061-T6Machined alternative for simpler parts.
- Aluminum A356 (Cast)Cast aluminum for repeat parts.
- Titanium Grade 5 (Ti-6Al-4V)For higher loads and temperatures.
- Maraging Steel 1.2709Printed tool steel for molds and inserts.
- 3D PrintingWhen metal printing is justified.
- Surface Finish GuideAnodizing, paint and drawing callouts.
Related materials
Metals
Aluminum 6061-T6
Versatile, weldable aluminum alloy with great machinability, anodizing quality, and corrosion resistance. One of the most common CNC materials.
Metals
Aluminum 7075-T6
High-strength Al-Zn-Mg-Cu alloy with roughly 1.7–1.8× the strength of 6061-T6. Machines very well but needs a protective finish and is not weldable. The choice when strength-to-weight matters most.
Metals
Aluminum 5052
Strain-hardened Al-Mg sheet alloy with good formability, very good weldability and excellent marine corrosion resistance. The default aluminum for bent sheet-metal parts.
Metals
Aluminum 3003
Al-Mn sheet alloy with excellent formability and weldability, good corrosion resistance and low strength. A practical choice for decorative panels, ducting, food-service equipment and light covers.
Metals
Aluminum A356
The standard heat-treatable Al-Si-Mg casting alloy. Pours well in sand and permanent molds, reaches useful T6 strength with good ductility, and suits pressure-tight housings and structural castings.
Metals
Stainless 304
The default austenitic stainless steel: excellent corrosion resistance indoors and in fresh water, well suited to food equipment and widely stocked. Slower to machine than aluminum because it work-hardens.
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