336.0 (AlSi12CuNiMg)
Eutectic "Y-alloy / Lo-Ex" type piston alloy with nickel, with very low thermal expansion for high-performance engines.
336.0 (formerly designated A332.0) is a eutectic "Y-alloy / Lo-Ex" type piston alloy with ~12% silicon and additions of nickel (2.0–3.0%), copper, and magnesium. The combination of eutectic silicon and nickel yields a very low thermal expansion coefficient (~19–20 µm/m·K) and excellent high-temperature dimensional stability — essential characteristics in high-performance engine pistons. Nickel forms refractory intermetallics that retain hot strength. We manufacture it from a primary aluminum base for precise composition control.
International Nomenclature
| Standard | Designation |
|---|---|
| AA (USA) | 336.0 (antes A332.0) |
| UNS | A03360 |
| EN (Europa) | EN AC-48000 · AlSi12CuNiMg (comparable) |
| ISO | Al-Si12CuNiMg |
Chemical Composition
| Element | Symbol | Percentage |
|---|---|---|
| Aluminum | Al | Balance |
| Silicon | Si | 11.0–13.0% |
| Iron | Fe | ≤1.2% |
| Copper | Cu | 0.50–1.5% |
| Manganese | Mn | ≤0.35% |
| Magnesium | Mg | 0.7–1.3% |
| Nickel | Ni | 2.0–3.0% |
| Zinc | Zn | ≤0.35% |
| Titanium | Ti | ≤0.25% |
| Others (each) | — | ≤0.05% |
Physical Properties
| Property | Value |
|---|---|
| Density | ~2.72 g/cm³ |
| Thermal Expansion Coeff. | ~19–20 µm/m·K |
| Melting Range | ~516–571 °C |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength (UTS) | ~248 MPa (T551) |
| Tensile Strength (UTS) | ~324 MPa (T65) |
| Yield Strength | ~193 MPa (T551) · ~296 MPa (T65) |
| Hardness | ~125 HB |
Key Characteristics
- Eutectic "Y-alloy / Lo-Ex" type piston alloy with nickel for hot strength
- Very low thermal expansion coefficient (~19–20 µm/m·K) for dimensional stability
- Nickel (2.0–3.0%) forms refractory intermetallics that retain high-temperature strength
- Eutectic composition (~12% Si) for excellent wear resistance
- Modern designation 336.0 (formerly A332.0)
- Manufactured from a primary aluminum base for precise composition control
Compared to Similar Alloys
332.0 (AlSi9.5Cu3) vs 336.0 (AlSi12CuNiMg)
Both are permanent-mold Al-Si-Cu cast-piston alloys, but they differ on the main metallurgical lever: 332.0 is hypoeutectic (~9.5% Si) with high copper (2.0–4.0%) for added strength, whereas 336.0 is eutectic (~12% Si) with nickel (2.0–3.0%) and low copper, a "Y-alloy / Lo-Ex" type that prioritizes a very low thermal expansion coefficient and hot strength.
| Dimension | 332.0 (AlSi9.5Cu3) | 336.0 (AlSi12CuNiMg) |
|---|---|---|
| Key alloying / composition | ~9.5% Si hypoeutectic, high Cu 2.0–4.0%, Mg 0.50–1.5%, Ni ≤0.50% | ~12% Si eutectic, Ni 2.0–3.0%, low Cu 0.50–1.5%, Mg 0.7–1.3% |
| Temper & strength (UTS) | T5: ~248 MPa UTS, ~193 MPa yield, ~105 HB | T551: ~248 MPa · T65: ~324 MPa UTS, up to ~296 MPa yield, ~125 HB |
| Thermal expansion (CTE) & dimensional stability | Si lowers CTE; good dimensional stability for pistons | Very low CTE ~19–20 µm/m·K; excellent high-temperature dimensional stability |
| Casting process | High-volume permanent mold; good castability | Permanent mold; eutectic Si for fluidity and wear resistance |
| Hot strength | Good hot strength via Cu (T5 precipitation hardening) | Superior hot strength: Ni forms refractory intermetallics |
| Weldability | Poor: high Cu (up to 4%) promotes hot cracking; not a weld-oriented alloy | Limited: an Al-Si-Cu-Ni piston alloy; likewise not intended for welding |
| Typical application | High-volume cast pistons, powertrain, compressor/pump pistons (Mexican automotive) | High-performance pistons, heavy-duty diesel, motorsport, high-temperature compressors |
332.0 (AlSi9.5Cu3): Choose 332.0 for high-volume automotive cast pistons, where high copper and the T5 temper deliver good strength and dimensional stability at competitive cost.
336.0 (AlSi12CuNiMg): Choose 336.0 when you need the lowest thermal expansion coefficient, greater hot strength (Ni), and higher strength (T65 temper, ~324 MPa) for high-performance, heavy-duty diesel, or racing pistons.
390.0 / A390 (AlSi17Cu4.5Mg) vs 336.0 (AlSi12CuNiMg)
Both are very-low-expansion Al-Si casting alloys, but they take different routes: 390.0/A390 is hypereutectic (16–18% Si, above the ~12.6% eutectic) with primary silicon crystals and high copper (4.0–5.0%) for maximum wear resistance, ideal for linerless blocks. 336.0 is eutectic (~12% Si) with nickel (2.0–3.0%) of the "Lo-Ex / Y-alloy" type, optimized for the hot strength and dimensional stability of high-performance pistons.
| Dimension | 390.0 / A390 (AlSi17Cu4.5Mg) | 336.0 (AlSi12CuNiMg) |
|---|---|---|
| Key composition / alloying | Hypereutectic: Si 16–18%, Cu 4.0–5.0%, Mg 0.45–0.65%; requires phosphorus (P) modification | Eutectic: Si 11–13%, Ni 2.0–3.0%, Cu 0.50–1.5%, Mg 0.7–1.3% |
| Si microstructure | Primary silicon crystals (hypereutectic) giving exceptional wear resistance | Eutectic silicon (~12%); nickel forms refractory intermetallics for hot strength |
| Heat treatment & strength | T6 (precipitation hardening): UTS ~280 MPa, yield ~265 MPa, elongation ~1%, 110–145 HB | T551: UTS ~248 MPa · T65: UTS ~324 MPa, yield ~296 MPa, ~125 HB |
| Thermal expansion (CTE) | ~18 µm/m·K (very low) | ~19–20 µm/m·K (low) |
| Machinability / processing | Primary Si crystals are highly abrasive: demanding machining (PCD tooling); grades 390.0, A390.0 (low Fe) and B390.0 (die casting) | Eutectic with less primary Si: more manageable machining than the hypereutectic; sand/permanent-mold casting |
| Weldability | Poor: the high copper (4.0–5.0%) makes it crack-sensitive; not recommended for structural welding | Limited: piston alloy with Cu and Ni; not intended as a weldable alloy |
| Typical application | Linerless engine blocks, cylinders, A/C compressors, pump bodies and high-wear hydraulic components | High-performance and heavy-duty diesel engine pistons, racing pistons, high-temperature compressor pistons |
390.0 / A390 (AlSi17Cu4.5Mg): Choose 390.0/A390 when you need maximum wear resistance and cylinder surfaces that run without a liner (linerless blocks, compressors, pumps), accepting more demanding machining and poor weldability from the high copper.
336.0 (AlSi12CuNiMg): Choose 336.0 when making high-performance pistons that demand hot strength and maximum dimensional stability, where the nickel (2.0–3.0%) and eutectic composition matter more than the extreme wear of primary silicon.
Industries & Applications
Automotive
High-performance engine pistons, heavy-duty diesel pistons
Motorsport
Racing pistons with low thermal expansion and high strength
Machinery
High-temperature compressor pistons, refractory components
Special Notes
336.0 was formerly designated A332.0; it should not be confused with the current 332.0. Its eutectic composition (~12% Si) plus nickel (2.0–3.0%) yield a very low thermal expansion coefficient (~19–20 µm/m·K), making it the classic "Lo-Ex / Y-alloy" alloy for high-performance pistons. We compare it to EN AC-48000 (AlSi12CuNiMg) for reference. We manufacture it from a primary aluminum base for precise composition control.
Frequently Asked Questions
What is alloy 336.0 (AlSi12CuNiMg) and what is it used for?
336.0 is a eutectic Al-Si-Cu-Ni-Mg casting alloy of the classic "Y-alloy / Lo-Ex" type, with ~12% silicon and nickel additions. Its very low thermal expansion coefficient and hot dimensional stability make it ideal for high-performance engine pistons, heavy-duty diesel pistons, racing (motorsport) pistons, and high-temperature compressor pistons.
What are the key alloying elements of 336.0 and what do they do?
Its main elements are silicon (11.0–13.0%, eutectic composition), nickel (2.0–3.0%), copper (0.50–1.5%), and magnesium (0.7–1.3%). Eutectic silicon provides excellent wear resistance, while nickel forms refractory intermetallics that retain strength at high temperature. The combination of eutectic silicon and nickel is what yields the very low thermal expansion coefficient (~19–20 µm/m·K).
Why does 336.0 have such a low thermal expansion coefficient, and why does it matter?
Its eutectic composition (~12% Si) combined with nickel (2.0–3.0%) produces a very low thermal expansion coefficient (~19–20 µm/m·K). This gives excellent dimensional stability as the engine heats up, controlling piston-to-cylinder clearance and reducing the risk of seizure. That is why it is the reference "Lo-Ex / Y-alloy" piston alloy for high-performance engines.
Is 336.0 heat-treatable? Which tempers and strengths does it offer?
Yes. As an Al-Si-Cu-Mg alloy it responds to heat treatment, thanks to copper and magnesium which provide precipitation hardening. In T551 temper it reaches a tensile strength of ~248 MPa and a yield strength of ~193 MPa; in T65 it rises to ~324 MPa tensile and ~296 MPa yield, with a hardness of ~125 HB. The T65 temper maximizes strength for the most demanding applications.
How does 336.0 differ from 332.0?
336.0 was formerly designated A332.0, so it should not be confused with the current 332.0 — they are distinct alloys. The key difference is 336.0's nickel content (2.0–3.0%), which together with its eutectic composition gives it a very low thermal expansion coefficient and hot strength. This is why 336.0 is the specific "Lo-Ex / Y-alloy" high-performance piston alloy.
How does Transformación Puebla manufacture 336.0, and from what feedstock?
We manufacture it from a primary aluminum base, which lets us precisely control the composition — especially the nickel (2.0–3.0%) and the eutectic silicon range (11.0–13.0%) that define its performance. For reference we compare 336.0 to the European EN AC-48000 (AlSi12CuNiMg). Fine control of the nickel intermetallics is essential to guarantee hot strength and the low expansion coefficient.
Need 336.0 (AlSi12CuNiMg)?
We manufacture this alloy in ingots, donuts, and bars to your exact specifications.