The differences between Aluminum 356.0 and Aluminum A356.0, both in the permanent mold cast, T6 condition:
| Property | Aluminum 356.0 | Aluminum A356.0 |
|---|---|---|
| Designation | 356.0 (Aluminum Association) | A356.0 (Aluminum Association) |
| UNS Number | A03560 | A13560 |
| EN Number | EN AC-42000 / EN AC-Al Si7Mg | EN AC-42000 / EN AC-Al Si7Mg |
| Typical Applications | Automotive parts (e.g., wheels, manifolds) | Similar applications with improved properties |
| Aluminum Content (%) | 90.1–93.3 | 91.1–93.2 |
| Magnesium (Mg, %) | 0.2–0.45 | 0.25–0.45 |
| Iron (Fe, %) | ≤0.6 | ≤0.2 |
| Copper (Cu, %) | ≤0.25 | ≤0.2 |
| Mechanical Properties | ||
| Yield Strength (MPa) | 164–182 | 241–263 |
| Tensile Strength (MPa) | 235–259 | 283–307 |
| Elongation (%) | 2.9–3.4 | 2.5–3 |
| Hardness (HV) | 89–105 | 100–110 |
| Fracture Toughness (MPa·m^0.5) | 19–21 | 35–40 |
| Thermal Properties | ||
| Melting Point (°C) | 582–648 | 560–610 |
| Thermal Conductivity (W/m·°C) | 150–162 | 149–155 |
| Machinability | Excellent (Speed: 101 m/min) | Excellent (Speed: 88.4 m/min) |
| Recyclability | Recyclable with energy efficiency | Recyclable with similar efficiency |
| 356.0 vs A356.0 |
Key Points
–A356.0 offers higher mechanical properties, including yield strength and tensile strength, making it more suitable for applications requiring higher performance.
-The 356.0 alloy has slightly lower impurity limits for some elements (e.g., Fe, Cu), which may influence its suitability for specific casting conditions.
-Both alloys exhibit excellent castability and corrosion resistance in similar environments.
The superior mechanical properties of A356.0 compared to 356.0 are primarily due to its stricter control of impurities and a slightly higher magnesium content. Here’s a detailed explanation:
Why A356.0 Has Higher Mechanical Properties
- Stricter Impurity Limits:
- Iron (Fe): In A356.0, Fe content is limited to a maximum of 0.2%, compared to 0.6% in 356.0. Iron can form brittle intermetallic compounds (such as Al-Fe-Si phases) in aluminum alloys, which act as stress concentrators and reduce ductility and strength.
- Copper (Cu): A356.0 allows a maximum of 0.2% Cu, compared to 0.25% in 356.0. Copper increases the susceptibility to corrosion and lowers the toughness of the material. Lower copper content in A356.0 contributes to better overall mechanical properties and corrosion resistance.
- Titanium (Ti) and Zinc (Zn): Both elements are limited to 0.2% and 0.1% respectively in A356.0, versus 0.25% and 0.35% in 356.0. This results in fewer unwanted secondary phases that might compromise mechanical performance.
- Higher Magnesium Content:
- Magnesium (Mg) is an essential alloying element for strengthening aluminum alloys through precipitation hardening. A356.0 has a slightly higher Mg range (0.25–0.45%) compared to 356.0 (0.2–0.45%), which increases its ability to form hardening precipitates (e.g., Mg2Si). This results in better strength and hardness after T6 heat treatment.
- Refinement of Microstructure:
- The stricter impurity control in A356.0 leads to a finer and more uniform microstructure. This reduces the formation of brittle intermetallics and results in improved fracture toughness and fatigue resistance.
- Optimized for High-Performance Applications:
- A356.0 is specifically developed for applications where mechanical performance is critical. The tighter compositional limits are engineered to meet the demands of industries such as aerospace, automotive, and high-end manufacturing.
Details on Key Mechanical Properties
| Property | Impact of Composition and Heat Treatment |
|---|---|
| Yield Strength (241–263 MPa) | Higher Mg content and fewer impurities improve the strength after T6 treatment. |
| Tensile Strength (283–307 MPa) | Precipitation of Mg2Si provides enhanced load-bearing capacity. |
| Elongation (2.5–3%) | Lower Fe content minimizes brittle phases, balancing strength and ductility. |
| Hardness (100–110 HV) | Controlled precipitation during T6 hardening contributes to increased hardness. |
| Fracture Toughness (35–40 MPa·m^0.5) | Fine microstructure reduces crack propagation, enhancing toughness. |
| Fatigue Strength (100–116 MPa) | Fewer defects and lower porosity improve resistance to cyclic loading. |
Applications Leveraging A356.0’s Advantages
- Aerospace Components: High toughness and strength make A356.0 ideal for structural parts subjected to dynamic loads.
- Automotive Parts: Wheels, suspension systems, and engine components benefit from its fatigue resistance and lightweight nature.
- Industrial Equipment: Pump housings and electronic enclosures exploit its improved machinability and corrosion resistance.
Conclusion
The higher mechanical properties of A356.0 stem from its optimized composition and refined microstructure. These characteristics make it the preferred choice for high-performance applications requiring excellent strength, toughness, and durability.