AlSi10MnMg (EN AC-43500)
The alloy of the future: designed for mega-castings and high-ductility structural die castings without heat treatment.
AlSi10MnMg (EN AC-43500) is the reference alloy for the mega-casting revolution and high-pressure structural die cast (HPDC) parts. Used by Tesla, BMW, Mercedes-Benz, and other OEMs to produce large structural parts in a single shot. Its copper-free design with controlled manganese (0.50–0.80%) enables high ductility in the F (as-cast) state, eliminating the need for heat treatment. Requires primary aluminum as the base due to its demanding iron limit (≤0.15%).
International Nomenclature
| Standard | Designation |
|---|---|
| EN (Europa) | EN AC-43500 · AlSi10MnMg |
| Equivalente AA | 365.0 / 367.0 (aprox.) |
| Nombres comerciales | Silafont-36 · Aural-2 · Maxxalloy-Ultra |
Chemical Composition
| Element | Symbol | Percentage |
|---|---|---|
| Aluminum | Al | Balance |
| Silicon | Si | 9.5–11.5% |
| Manganese | Mn | 0.50–0.80% |
| Magnesium | Mg | 0.10–0.50% |
| Iron | Fe | ≤0.15% |
| Copper | Cu | ≤0.05% |
| Titanium | Ti | ≤0.15% |
| Strontium | Sr | 0.01–0.03% |
| Zinc | Zn | ≤0.07% |
Physical Properties
| Property | Value |
|---|---|
| Density | 2.65 g/cm³ |
| Melting Range | 555–600 °C |
| Thermal Conductivity | 120–140 W/m·K |
| Electrical Conductivity | ~28% IACS |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength (UTS) | 280–310 MPa (F (as-cast)) |
| Yield Strength | 130–160 MPa (F (as-cast)) |
| Elongation | 6–12% (F (as-cast)) |
| Hardness | ~75 HB |
Key Characteristics
- Designed for mega-castings and large-format structural HPDC parts
- High ductility in F state (as-cast): 6–12% elongation without heat treatment
- Copper-free (Cu ≤0.05%) for maximum corrosion resistance and ductility
- Mn (0.50–0.80%) neutralizes iron by forming compact phases instead of brittle needles
- Ultra-low iron (≤0.15%) requires primary aluminum base
- Eliminates heat treatment → reduces cost and distortion in large parts
Industries & Applications
Automotive — BEV Structural
Underbody mega-castings (Tesla), rear subframes, shock towers, battery tray components
Automotive — Body-in-White
Structural junction nodes, pillar reinforcements, crash management components
Transportation
Structural components for electric and autonomous vehicles
Special Notes
AlSi10MnMg is the alloy transforming the automotive industry through mega-castings. Tesla uses it for the Giga Press machine, producing the Model Y rear underbody in a single shot (previously 70+ stamped and welded parts). Manganese is key: it forms compact, rounded Al₁₅(Mn,Fe)₃Si₂ intermetallics, neutralizing iron's negative effects. This enables good ductility even at HPDC solidification rates. We manufacture this alloy exclusively with P1020/P0610 primary aluminum to meet the strict Fe ≤0.15% limit.
Frequently Asked Questions
What is AlSi10MnMg (EN AC-43500) and what is it used for?
It is a structural aluminum-silicon alloy designed for high-pressure die casting (HPDC), known as the mega-casting alloy. OEMs such as Tesla, BMW and Mercedes-Benz use it to produce large structural parts in a single shot: BEV underbody, rear subframes, shock towers and battery-tray components. Its best-known trade name is Silafont-36 (also Aural-2 and Maxxalloy-Ultra).
What is its composition and what does each element do?
Its base is aluminum with 9.5–11.5% silicon (castability), 0.50–0.80% manganese and 0.10–0.50% magnesium. Silicon provides fluidity and low shrinkage; magnesium enables hardening, and manganese neutralizes iron by forming compact Al₁₅(Mn,Fe)₃Si₂ phases instead of brittle needles. It is essentially copper-free (Cu ≤0.05%) and keeps iron ultra-low (Fe ≤0.15%).
Does it need heat treatment? What mechanical properties does it reach?
It does not require heat treatment: it reaches high ductility already in the F (as-cast) state, with 6–12% elongation, 280–310 MPa tensile strength (UTS), 130–160 MPa yield strength and ~75 HB hardness. Eliminating heat treatment lowers cost and avoids the distortion typical of large die-cast parts.
Why is it ideal for high-pressure die casting (HPDC) and mega-castings?
It is purpose-designed for large-format structural HPDC parts. The controlled manganese forms compact, rounded intermetallic phases that neutralize iron's effect, preserving good ductility even at the high solidification rates of HPDC. This is why Tesla uses it on the Giga Press to cast the Model Y rear underbody in a single shot, replacing 70+ stamped and welded parts.
How does it behave against corrosion?
It offers very good corrosion resistance thanks to its copper-free design (Cu ≤0.05%): the absence of copper avoids the galvanic coupling that degrades other Al-Si-Cu alloys. Combined with its high ductility, this makes it suitable for structural components of electric and autonomous vehicles.
Does TP make this alloy from recycled wheel scrap or only from primary aluminum?
We manufacture it exclusively from primary aluminum (P1020/P0610). The iron limit is very strict (Fe ≤0.15%) and recycled scrap —including car wheels (rin)— contributes too much iron to meet it, so a primary aluminum base is required to guarantee the composition and structural performance.
How does it differ from an Al-Si-Cu alloy such as A380?
A380 is a copper-bearing die-casting alloy optimized for non-structural parts with good castability but low ductility. AlSi10MnMg is structural: copper-free, with manganese and ultra-low iron, it prioritizes ductility and mechanical integrity in the as-cast state for parts that must carry load and absorb crash energy. That is why it is the choice for mega-castings, while A380 covers more conventional functional components.
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