AlSi7Mg0.6 (A357)
The high-strength version of A356, with higher magnesium for safety-critical automotive structural and aerospace applications.
A357 (AlSi7Mg0.6) is the premium version of A356, with higher magnesium content (0.45–0.60%) that increases mechanical strength ~15% after T6 heat treatment. It is the preferred alloy for safety-critical automotive structural parts (nodes, shock towers, subframes) and aerospace components. The A357.2 version requires ultra-low iron (≤0.09%), demanding P0610 primary aluminum as the base. We manufacture this alloy exclusively with primary aluminum base.
International Nomenclature
| Standard | Designation |
|---|---|
| AA (USA) | A357.0 / A357.2 |
| EN (Europa) | EN AC-42200 · AlSi7Mg0.6 |
| DIN (Alemania) | G-AlSi7Mg0.6 / 3.2372 |
| ISO | AlSi7Mg0.6 |
| JIS (Japón) | AC4CH |
Chemical Composition
| Element | Symbol | Percentage |
|---|---|---|
| Aluminum | Al | Balance |
| Silicon | Si | 6.50–7.50% |
| Magnesium | Mg | 0.45–0.60% |
| Iron | Fe | ≤0.20% (A357) · ≤0.09% (A357.2) |
| Copper | Cu | ≤0.20% |
| Manganese | Mn | ≤0.10% |
| Zinc | Zn | ≤0.10% |
| Titanium | Ti | ≤0.20% |
| Beryllium | Be | 0.04–0.07% (opcional) |
Physical Properties
| Property | Value |
|---|---|
| Density | 2.68 g/cm³ |
| Melting Range | 557–613 °C |
| Thermal Conductivity | 150–160 W/m·K |
| Electrical Conductivity | 35–40% IACS |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength (UTS) | ~345 MPa (T6) |
| Yield Strength | ~290 MPa (T6) |
| Elongation | 2–5% (A357.2 T6: 5–8%) |
| Hardness | ~100 HB |
Key Characteristics
- High-strength version of A356, with ~15% higher mechanical strength in T6
- Higher Mg content (0.45–0.60%) vs. A356 (0.25–0.45%) drives mechanical property improvement
- A357.2 with ultra-low iron (≤0.09%) for superior ductility and fatigue life
- Requires primary aluminum base (P1020 or P0610) to guarantee low iron content
- Heat-treatable in T6 and T61 tempers for optimal properties
- Compatible with strontium (Sr) modification for eutectic refinement
Compared to Similar Alloys
AlSi7Mg (A356) vs AlSi7Mg0.6 (A357)
These are sibling Al-Si-Mg alloys with identical silicon (6.5–7.5%), so they share fluidity and castability. The key difference is magnesium: A356 runs 0.25–0.45% while A357 raises it to 0.45–0.60%, which after T6 heat treatment gives A357 ~15% higher mechanical strength, with even tighter iron control.
| Dimension | AlSi7Mg (A356) | AlSi7Mg0.6 (A357) |
|---|---|---|
| Magnesium (key alloying element) | 0.25–0.45% Mg — Si 6.5–7.5%, Cu ≤0.20% | 0.45–0.60% Mg — same Si 6.5–7.5%; optional Be 0.04–0.07% |
| Heat treatment & strength (T6) | T6: UTS ~310 MPa, yield ~230 MPa, ~75 HB. Tempers F/T5/T6/T61/T71 | T6: UTS ~345 MPa, yield ~290 MPa, ~100 HB (~15% higher). Tempers T6/T61 |
| Ductility / elongation (T6) | 3–10%; A356.2 (Fe ≤0.12%) reaches 6–10% | 2–5%; A357.2 (Fe ≤0.09%) reaches 5–8% — more strength, slightly less elongation |
| Iron control / base metal | Fe ≤0.20% (A356) · ≤0.12% (A356.2); primary or secondary base per spec | Fe ≤0.20% (A357) · ≤0.09% (A357.2); manufactured exclusively from primary aluminum base (P0610) |
| Casting process | Excellent fluidity and low shrinkage; permanent mold, sand, gravity. Sr-modifiable | Same castability (identical Si); strontium-modifiable for eutectic refinement |
| Typical application | Aluminum wheels, cylinder heads, suspension, landing gear — the versatile workhorse | Structural nodes, shock towers, subframes, aerospace — top safety-critical strength |
AlSi7Mg (A356): Choose A356 when you need the versatile reference casting alloy with maximum ductility and fatigue life (e.g. A356.2 wheels) and the flexibility of a primary or secondary base.
AlSi7Mg0.6 (A357): Choose A357 when you need ~15% higher strength after T6 for safety-critical structural parts (nodes, subframes, aerospace), accepting the tighter iron control and primary-aluminum base.
Industries & Applications
Structural Automotive
Structural nodes, shock towers, subframes, safety-critical suspension parts
Aerospace
Aircraft structural components, landing gear parts, turbine housings
Defense
Armored vehicle components, missile structural parts
Special Notes
A357 is identical to A356 except for its higher magnesium content: 0.45–0.60% vs. 0.25–0.45%. This increase achieves UTS of ~345 MPa vs. ~310 MPa in T6. The A357.2 version requires Fe ≤0.09% (even more restrictive than A356.2's ≤0.12%), so we manufacture this alloy exclusively from P0610 primary aluminum base. It is the preferred alloy of OEMs like VW/Audi for next-generation structural automotive parts.
Frequently Asked Questions
What is A357 (AlSi7Mg0.6) alloy and what is it used for?
A357 is a premium Al-Si-Mg casting alloy (3xx.x series), the high-strength version of A356 with higher magnesium content (0.45–0.60%). It is the preferred choice for safety-critical structural automotive parts such as structural nodes, shock towers, subframes and suspension parts, as well as for aerospace components (aircraft structures, landing gear) and defense applications.
What are the key alloying elements in A357 and what do they contribute?
A357 combines silicon (6.50–7.50%), which provides excellent fluidity and castability, with magnesium (0.45–0.60%), which after T6 heat treatment forms Mg2Si precipitates that drive mechanical strength. Iron is kept low (≤0.20% in A357; ≤0.09% in A357.2) to preserve ductility and fatigue life. Beryllium (0.04–0.07%) is added optionally.
Is A357 heat-treatable and what strength does it reach?
Yes, A357 is heat-treatable in T6 and T61 tempers for optimal properties. In the T6 condition it reaches a tensile strength (UTS) of ~345 MPa, a yield strength of ~290 MPa and a hardness of ~100 HB. Elongation is 2–5%, rising to 5–8% in the ultra-low-iron A357.2 T6 variant.
How does A357 differ from A356?
A357 is identical to A356 except for its higher magnesium content: 0.45–0.60% versus 0.25–0.45% in A356. That extra magnesium raises mechanical strength by about 15% in T6, reaching ~345 MPa UTS versus ~310 MPa for A356. In addition, the A357.2 version requires an even more restrictive iron level (≤0.09%) than A356.2 (≤0.12%).
Can Transformación Puebla produce A357 from recycled wheel aluminum?
No. Because of its low-iron requirement (≤0.20% in A357 and ≤0.09% in A357.2), we manufacture this alloy exclusively from a primary aluminum base (P1020 or P0610). The A357.2 version demands P0610 primary aluminum to guarantee the ultra-low iron, since recycled wheel aluminum tends to accumulate iron that would prevent meeting the specification.
Does A357 support strontium modification and why does it matter?
Yes, A357 is compatible with strontium (Sr) modification, which refines the eutectic silicon structure. This eutectic refinement improves ductility and mechanical properties, which is especially valuable for the safety-critical structural parts this alloy is used for.
Under which designations and standards is A357 known?
A357 is recognized internationally under several standards: A357.0 / A357.2 (AA, USA); EN AC-42200 · AlSi7Mg0.6 (EN, Europe); G-AlSi7Mg0.6 / 3.2372 (DIN, Germany); AlSi7Mg0.6 (ISO); and AC4CH (JIS, Japan). It is the preferred alloy of OEMs such as VW/Audi for next-generation structural automotive parts.
Need AlSi7Mg0.6 (A357)?
We manufacture this alloy in ingots, donuts, and bars to your exact specifications.