Casting aluminium alloys can be classified into four categories based on their major alloying elements:
1. Aluminium-Silicon Alloys (also known as “Silumin” or “Si-Al Alloys”)
- Have good casting and wear resistance properties.
- Low thermal expansion coefficient.
- The most widely used type of cast aluminum alloy, with silicon content ranging from 10% to 25%.
- Sometimes 0.2% to 0.6% magnesium is added to improve the mechanical properties and heat resistance.
- Widely used for structural parts such as housings, cylinders, boxes, and frames.
2. Aluminium-Copper Alloys
- A copper content of 4.5% to 5.3% achieves the best strengthening effect.
- Appropriate addition of manganese and titanium can significantly improve room temperature, high temperature strength, and casting performance.
- Mainly used for making sand castings thatsustain large dynamic and static loads and have simple shapes.
3. Aluminium-Magnesium Alloys
- The casting aluminum alloy with the lowest density (2.55 g/cm3) and the highest strength (around 355 MPa).
- The best strengthening effect is achieved with 12% magnesium content.
- The alloy has good corrosion resistance in the atmosphere and seawater, and good comprehensive mechanical properties and machinability at room temperature.
- This alloy finds application in radar bases, aircraft engine housings, propellers, landing gear, and even decorative materials.
4. Aluminium-Zinc Alloys
- Manufacturers often add silicon and magnesium elements to improve performance, creating what’s known as “Zinc-Silicon-Aluminum Alloys.
- Under casting conditions, this alloy has a quenching effect, i.e. “self-quenching”.
- This alloy doesn’t require heat treatment for use, and gains even higher strength after solution heat treatment.
- Stabilization treatment ensures dimensional stability, making this alloy ideal for models, patterns, and equipment supports.
Casting Aluminoum Alloy-Main Elements Comparison
| Chmeical Symbol | Si | Cu | Mg | Mn |
| Alloy | ||||
| AlSi10Mg | 9.0~11.0 | 0.05 | 0.20~0.45 | 0.45 |
| AlSi7Mg03 | 6.5~7.5 | 0.05 | 0.25~0.45 | 0.1 |
| ASi7Mg06 | 6.5~7.5 | 0.05 | 0.10~0.60 | 0.1 |
| AlSi10MnMg | 9.0~11.5 | 0.05 | 0.10~0.60 | 0.40~0.80 |
| AlSi12 | 10.5~13.5 | 0.05 | 0.45 | 0.1 |
| AlSi9Cu3(Fe) | 8.0~11.0 | 2.0~4.0 | 0.15~0.55 | 0.55 |
| AlSi8Cu3 | 7.5~9.5 | 2.0~3.5 | 0.05~0.55 | 0.15~0.65 |
| AlSi7Cu3Mg | 6.5~8.0 | 3.0~4.0 | 0.30~0.60 | 0.20~0.65 |
| AlCu4MgTi | 0.2 | 4.2~5.0 | 0.15~0.35 | 0.1 |
| AlCu4MnMg | 0.1 | 4.0~5.0 | 0.15~0.50 | 0.20~0.50 |
| AlMg3 | 0.55 | 0.05 | 2.5~3.5 | / |
Comparison with Wrought Aluminum Alloys
Aluminum Casting alloys have the same alloy system as wrought aluminum alloys and the same strengthening mechanism (except for strain strengthening). The main difference between them is that the maximum silicon content in cast aluminum alloys exceeds the silicon content in most wrought aluminum alloys. In addition to containing strengthening elements, casting aluminum alloys must also contain a sufficient amount of eutectic elements (usually silicon) to give the alloy sufficient fluidity and to easily fill the shrinkage cavities of the casting during casting.
With a wide variety of casting aluminum alloys available, selecting the right die cast aluminum material and process is crucial for product performance. Sunrise Metal specializes in aluminum die casting, and with our extensive experience and expertise, we can provide customized solutions to meet your specific requirements. Contact us for a free consultation and quote.