Material Name : GD-ALSi12
Material Identification & Standards
GD-ALSi12 is a eutectic aluminum–silicon die‑casting alloy (≈12% Si). Equivalent designations include:
- JIS (Japan): ADC1
- AA (USA): A413
- BS (UK): LM6 (BS 1490)
- DIN (Germany): GD‑AlSi12 (DIN 1725)
- ISO (International): Al‑Si12 (ISO 3522)
- Common Use Type : Al‑Si‑Mg die casting alloy
- EN (Europe): EN AC-44100 (EN 1706)
EN 1706 is a standard designation, officially titled:
EN 1706: Aluminium and aluminium alloys — Castings — Chemical composition and mechanical properties.
It is a European Standard (EN) that specifies the chemical composition and mechanical properties of cast aluminum alloys.
Therefore, all European cast aluminum alloys, such as EN AC‑44300, EN AC‑44100, EN AC‑43000, etc., are defined and governed under the framework of EN 1706.
Chemical Composition
- Aluminum (Al): Balance
- Silicon (Si): 11.0–13.0%
- Copper (Cu): ≤ 1.0%
- Magnesium (Mg): ≤ 0.3%
- Zinc (Zn): ≤ 0.5%
- Iron (Fe): ≤ 1.3%
- Manganese (Mn): ≤ 0.3%
- Nickel (Ni): ≤ 0.5%
- Tin (Sn): ≤ 0.1%
- Lead (Pb): ≤ 0.2%
This composition ensures excellent castability and stable mechanical properties.
Mechanical & Physical Properties
| Property | Typical Value Range |
| Tensile Strength | 240–290 MPa |
| Yield Strength | 130–150 MPa |
| Elongation | 1–4% |
| Brinell Hardness | 60–80 HB |
| Density | ~2.67 g/cm³ |
| Melting Temperature | 560–580 °C |
Thermal and Electrical Properties
| Property | Typical Value Range |
| Thermal Conductivity | ~120 – 140 W/m·K |
| Electrical Conductivity | ~24% IACS（~13–14 MS/m） |
| Thermal Expansion Coefficient | ~21 – 22 µm/m·K |
Pros & Cons Summary
| Feature | Pros | Cons |
| Strength & Toughness | Moderate mechanical strength; good compressive strength | Low ductility; relatively brittle under tensile loads |
| Corrosion Resistance | Good general corrosion resistance (stable oxide layer) | – (no major drawback noted) |
| Castability | Excellent fluidity and thin-wall castability | – (requires careful shrinkage control) |
| Machinability | Machinable and polishable with standard tools | Silicon content is abrasive; tool wear must be managed |
GD-ALSi12 alloy chemistry yields excellent castability (high fluidity, low shrinkage) and good corrosion resistance in normal and humid environments. Its main drawback is low ductility: it can crack under overloading. The high Si content also makes it somewhat abrasive on cutting tools, so machining conditions should be optimized (though it machines well when handled properly).
Castability & Corrosion Resistance
GD-ALSi12 is well-suited to pressure die casting of complex, thin-walled components. As an approximately eutectic Al–Si alloy, it has very good melt fluidity and filling ability, minimizing shrinkage defects. It tolerates rapid filling and can produce intricate, sharp‑corner shapes. Unlike high‐copper or high‐magnesium alloys, its Al–Si composition forms a stable aluminum oxide, giving strong corrosion resistance in air, humidity, and even marine environments.
In practice, GD-ALSi12 requires standard die-casting mold design (well‑vented cavities, controlled cooling) to avoid porosity or hot tears. Its high silicon also causes significant solidification shrinkage, so gating and cooling must be arranged to prevent voids. Nevertheless, the alloy consistently produces smooth cast surfaces and fine grains, making post‐machining and finishing reliable.
Key Characteristics
- Eutectic Al–Si (~12% Si) alloy: Exceptional cast fluidity for thin-walled, complex parts.
- Moderate strength, low ductility: Tensile ~240–290 MPa, elongation ~1–4% – suitable for moderate-load structural use.
- Excellent corrosion resistance: Al–Si alloy resists oxidation and salt‑water exposure.
- Good machinability: Can be machined, welded, brazed and polished with common methods.
- Lightweight and dimensionally stable: Density ~2.67 g/cm³, low thermal expansion. Ideal for weight‑sensitive designs.
Applications
GD-ALSi12 is widely used where strength and casting flexibility are needed more than absolute load capacity. Typical applications include:
- Automotive parts: Structural housings, engine covers, gearbox and pump housings, brackets and frames (e.g. engine mounting frames).
- Electronics and electrical: Enclosures and heat sinks for electronics or motors (e.g. hard-disk drive housing, charger connectors).
- Consumer and mechanical: Complex lamp or appliance bodies, thin‑walled gear cases, pump and compressor housings.
- Outdoor/Marine: Die‑cast parts exposed to weather or salt (radiator housings, marine engine components) due to its corrosion resistance.
Its reliability in castability and corrosion performance makes GD-ALSi12 ideal for mid‑strength structural applications in automotive, electronics, and machinery.
Conclusion & Recommendation
GD-ALSi12 is a balanced aluminum–silicon die-casting alloy. It offers exceptional castability and good corrosion resistance while retaining moderate strength and hardness. In demanding environments where complex shapes and corrosion resistance are required (e.g. automotive housings, electrical enclosures, marine parts), GD-ALSi12 is a top choice.
Compared to high-silicon or Al–Mg alloys, GD-ALSi12 trades off some strength for easier casting and finishing. Designers should consider it for lightweight, intricate cast components that do not require very high ductility. Its proven use in engine and equipment housings, coupled with wide international standardization, make GD-ALSi12 a highly reliable candidate for die-cast structural parts.