Direct Answer: ADC12 (JIS H 5302 / Al-Si11Cu3) and A380 (ASTM B85 / Al-Si8.5Cu3.5) are secondary Al-Si-Cu alloys engineered for high-fluidity thin-wall die casting of electronics, automotive, and appliance housings, with A380 offering slightly higher impact toughness and ADC12 delivering superior fluidity in ultra-thin cooling fins. By contrast, A356 (AlSi7Mg0.3) is a low-iron, copper-free primary hypoeutectic alloy poured via gravity permanent mold, low-pressure casting, sand, or investment casting because it can be T6 solution heat-treated, welded, and anodized for safety-critical structural components.
Direct Foundry & CNC Manufacturing — Pingdu, Qingdao
Qingdao Yucheng Machine (YCUMETAL) operates a 34,000 m² integrated casting and CNC machining facility in Pingdu, Qingdao (approx. 50 km from Qingdao Port). We pour and finish-machine stainless steel, carbon & alloy steel, ductile/grey iron, aluminum, and copper/bronze alloys across silica-sol investment casting, sand casting, lost foam, gravity, and low-pressure casting.
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1. Technical Comparison Matrix: ADC12 vs A380 vs A356-T6 Aluminum
Engineers frequently ask whether an A380 or ADC12 housing can be substituted with A356-T6 (or vice versa) during prototyping or medium-volume production. Compare their chemical limits and mechanical performance below:
| Parameter | ADC12 (JIS H 5302 / A383 equiv.) | A380 (ASTM B85 / EN AC-46000) | A356-T6 (ASTM B26 / B108 / EN AC-42100) |
|---|---|---|---|
| Silicon (Si) wt.% | 9.6 – 12.0% (Near-eutectic; maximum fluidity) | 7.5 – 9.5% | 6.5 – 7.5% |
| Copper (Cu) & Magnesium (Mg) | Cu 1.5–3.5%, Mg ≤0.30% | Cu 3.0–4.0%, Mg ≤0.10% | Cu ≤0.20%, Mg 0.25–0.45% (Mg2Si age hardening) |
| Iron (Fe) Limit | ≤ 1.3% (prevents die soldering) | ≤ 1.3% | ≤ 0.20% (maximizes ductility & fracture toughness) |
| Primary Casting Processes | High-pressure die casting | High-pressure die casting | Gravity permanent mold, low-pressure, sand & lost-wax |
| Tensile / Yield Strength | ~310 MPa / ~150 MPa (as-cast skin) | ~324 MPa / ~160 MPa (as-cast skin) | 230–280 MPa / 165–210 MPa (uniform through full cross-section in T6) |
| Elongation (A5) | 1.5 – 3.0% (brittle under shock) | 2.5 – 3.5% | 5.0 – 10.0% (high structural ductility) |
| T6 Heat Treatment & TIG Welding | No (blisters during solution heat treat) | No | Yes (T6 solution + artificial aging; fully weldable) |
| Thermal Conductivity & Anodizing | ~96 W/m·K; turns dark grey when anodized due to high Si/Cu | ~96 W/m·K; poor decorative anodizing | 150–160 W/m·K; clear protective anodizing & chromate conversion |
2. Why Gravity & Low-Pressure Cast A356-T6 Outperforms Die-Cast ADC12/A380 in Structural & Pressure Parts
While ADC12 and A380 excel at high-volume thin-wall enclosures (>50,000 pcs/year), high-velocity die injection traps air bubbles inside the casting interior. If you machine deeper than 0.8 mm into an ADC12 or A380 boss, internal gas porosity is exposed—causing hydraulic leakage and preventing T6 solution heat treatment at 540 °C.
At YCUMETAL’s 34,000 m² Pingdu facility, we pour A356 and ZL101A/ZL104 aluminum alloys via low-pressure casting (filling the die uphill from bottom to top under 0.02–0.06 MPa dry air pressure) and gravity permanent mold casting with rotary argon degassing and Sr modification. The result is an X-ray/CT-verified dense core that can be T6 heat-treated, deep-pocket CNC machined, and pressure-tested for automotive gearbox housings, robotic arm brackets, and 5G telecom heat-sink enclosures. Contact our engineering team to evaluate your 3D CAD file.
Frequently Asked Questions (Engineering FAQ)
Are ADC12 and A380 aluminum interchangeable on engineering drawings?
For most non-structural die-cast enclosures and motor housings, ADC12 and A380 are functionally equivalent and interchangeable. ADC12 has slightly higher silicon (9.6–12.0% vs 7.5–9.5% in A380), giving it better fluidity for thin radiator fins and complex ribs, while A380 has slightly higher copper and lower silicon, yielding marginally higher impact resistance.
Can I prototype an A380 or ADC12 die-cast housing using A356 sand, investment, or gravity casting?
Yes. Before committing to expensive high-pressure die-casting steel tooling, OEMs routinely produce 10 to 2,000 functional assemblies at YCUMETAL in A356-T6 via sand casting, lost-foam casting, or gravity permanent mold casting followed by 5-axis CNC machining—achieving higher ductility, zero internal gas blistering, and higher thermal conductivity (150 W/m·K vs 96 W/m·K).
Why does ADC12 turn dark grey or blotchy during anodizing?
ADC12 contains 9.6–12% silicon and 1.5–3.5% copper. During sulfuric acid anodizing, aluminum dissolves and oxidizes while elemental silicon and copper intermetallics remain trapped in the oxide layer, producing a dark grey smudge. For clear or uniform anodized finishes, low-copper A356 or Al-Mg casting alloys are required.
Related Foundry Specifications & Engineering Guides
Core Capabilities: Gravity Permanent Mold Casting · Low-Pressure Aluminum Casting · Electronics & Telecom Castings · Robotics Aluminum Castings · Pillar Guide: ADC12 vs A380 vs A356 Aluminum Casting Alloys: Composition, T6 Strength & Process Selection
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