Your drawing says A380, the foundry quote comes back as A383, and the thin rib on your housing still shows cold shuts. Alloy questions usually arrive exactly like this, late in a project and tied to a defect. A383 aluminum exists for that situation. It is the castability-focused sibling of A380, giving up a small margin of strength for measurably better die filling and hot cracking resistance. This guide compares the two alloys on composition, properties, castability, cost, and sourcing, so you can specify the right one before the mold is cut.
Both alloys belong to the same aluminum-silicon-copper family used in high-pressure aluminum die casting, and on a datasheet they look nearly interchangeable. The differences appear on the shop floor: in scrap rates on thin-wall parts, in cracking around bosses, and in how forgiving the melt is when gate design or die temperature drifts. The sections below quantify each difference and close with a practical selection rule.
A383 Aluminum vs A380 at a Glance
A383 aluminum is a modified version of A380 with higher silicon (9.5–11.5% vs 7.5–9.5%) and lower copper (2.0–3.0% vs 3.0–4.0%). It fills thin walls and complex cavities more easily and resists hot cracking better, while sacrificing a small amount of tensile strength. A380 stays the cheaper, more available default for conventional part geometries.
| Dimension | A380 Aluminum | A383 Aluminum |
|---|---|---|
| Silicon content | 7.5–9.5% | 9.5–11.5% |
| Copper content | 3.0–4.0% | 2.0–3.0% |
| Tensile strength (typical) | ~324 MPa | ~310 MPa |
| Die filling / fluidity | Very good | Excellent |
| Hot cracking resistance | Good | Very good |
| Thin-wall capability | Good down to ~2 mm | Better below 2 mm and in fine ribs |
| Availability | Widest of all die casting alloys | Common, slightly less stocked |
| Relative material cost | Baseline | Small premium |
| Best for | Conventional geometries, global sourcing | Thin walls, long flow paths, cracking-prone parts |
The table compresses the whole comparison. If your part is a simple bracket or housing with walls above 2 mm, you can stop reading here and stay with A380. The sections below explain what each row means in production.
Chemical Composition: More Silicon, Less Copper
Under ASTM B85, A383 carries 9.5–11.5% silicon against 7.5–9.5% for A380, and 2.0–3.0% copper against 3.0–4.0%. The extra silicon improves fluidity and reduces solidification shrinkage. The reduced copper trims strength slightly and improves corrosion behavior. Iron, manganese, zinc, and other limits are nearly identical between the two grades.
| Element | A380.0 (ASTM B85) | A383.0 (ASTM B85) |
|---|---|---|
| Silicon (Si) | 7.5–9.5% | 9.5–11.5% |
| Copper (Cu) | 3.0–4.0% | 2.0–3.0% |
| Iron (Fe) | 1.3% max | 1.3% max |
| Manganese (Mn) | 0.5% max | 0.5% max |
| Magnesium (Mg) | 0.10% max | 0.10% max |
| Nickel (Ni) | 0.5% max | 0.3% max |
| Zinc (Zn) | 3.0% max | 3.0% max |
| Tin (Sn) | 0.35% max | 0.15% max |
| Aluminum (Al) | Balance | Balance |
Two details in this table drive everything else. First, the aluminum-silicon eutectic sits at 12.6% silicon, so A383 solidifies closer to the eutectic point with a narrower freezing range. The melt feeds better and stays fluid longer, which is the physical reason behind its die filling advantage. Second, copper strengthens the alloy through CuAl2 phases but hurts corrosion resistance, so the lower-copper A383 holds up marginally better in humid or mildly corrosive service.
Mechanical and Physical Properties
A380 is modestly stronger: roughly 324 MPa typical tensile strength versus 310 MPa for A383, with yield strength near 159 and 152 MPa respectively. Elongation is similar at about 3.5%. Density is effectively equal, 2.71 versus 2.74 g/cm³, so a part redesigned from A380 to A383 changes weight by around 1%.
| Property (as-cast, typical) | A380 | A383 |
|---|---|---|
| Ultimate tensile strength | 324 MPa | 310 MPa |
| Yield strength (0.2% offset) | 159 MPa | 152 MPa |
| Elongation (in 50 mm) | 3.5% | 3.5% |
| Hardness | 80 HB | 75 HB |
| Density | 2.71 g/cm³ | 2.74 g/cm³ |
| Melting range | 540–595 °C | 516–582 °C |
| Thermal conductivity | ≈96 W/m·K | ≈96 W/m·K |
The strength gap is small enough that casting quality usually matters more than the alloy choice. Porosity, wall thickness, and gate design shift real-world strength by more than the 14 MPa between these grades. Choosing A380 purely for its tensile number rarely survives contact with actual test data; request tensile bars and material certificates from your supplier if the margin matters on your drawing.
Castability: Where A383 Aluminum Earns Its Premium
A383 fills thin walls, fine ribs, and long flow paths more reliably because its higher silicon content keeps the melt fluid longer and narrows the freezing range. It also resists hot tearing at thick-to-thin transitions better than A380. On difficult geometries, foundries consistently report lower cold shut and misrun scrap with the higher-silicon grade.
Three situations justify the switch. Walls in the 1.5–2.5 mm band, where A380 begins to misrun at the far end of the cavity. Fine ribs, small bosses, and deep pockets, where flow length is long relative to section thickness. And parts with a production history of hot cracks near intersecting walls, where the better feeding behavior of A383 reduces tearing during solidification.
Alloy fluidity works together with tooling, not in place of it. At our facility, mold filling is validated with JSCAST casting simulation and UG 3D modeling at the mold design stage, before any die steel is cut. Pairing a higher-fluidity alloy with a verified gate and overflow design is what actually moves the scrap number on a thin-wall job.
Is A383 the Same as ADC12?
They are near-equivalents rather than identical grades. ADC12 is the Japanese JIS grade with 9.6–12.0% silicon and 1.5–3.5% copper, a range that overlaps A383 almost completely. In global sourcing the two are routinely treated as interchangeable, and most Asian foundries quote ADC12 when a North American drawing calls for A383. Confirm the exact limits against your purchase standard before switching designations.
This matters in practice because drawings and supply chains often cross regions. A part specified as A383 in the US will usually be cast in ADC12 in China or Japan without any engineering change. For a deeper look at each grade, see our guides to ADC12 aluminum and A380 aluminum.
Where A413 Fits In
A413 (413.0) pushes silicon further, to 11.0–13.0%, essentially at the eutectic composition. It delivers the best fluidity and pressure tightness of the common die casting alloys, at lower strength, and suits intricate or leak-tight parts such as pump bodies and valve housings. Evaluate it when A383 still leaves filling or sealing problems unsolved.
Think of the three grades as a fluidity ladder: A380 at the base, A383 one step up, A413 at the top. Each step trades a little strength and machinability for better flow and tightness. Most parts never need to climb past the first step, but knowing the ladder exists saves a redesign when a difficult cavity refuses to fill.
Cost, Availability, and Part Weight
A380 is the most widely stocked die casting alloy in the world and usually the cheapest per kilogram. A383 carries a modest material premium and occasionally longer lead times, yet on complex parts it can lower total cost by cutting scrap, rework, and leak-related rejects. Part weight is effectively identical between the two, since density differs by only about 1%.
The cost question deserves a total-cost answer rather than a price-per-kilo answer. Better die filling means fewer cold shuts, which means less scrap and less sorting, which means a lower finished-piece cost on difficult parts. On simple parts the calculation flips: A380 wins through availability, faster quoting, and the fact that nearly every die caster on the planet runs it daily. Ingot pricing for both grades tracks the same aluminum market, so the alloy premium stays stable relative to material swings.
How to Choose Between A383 and A380
Choose A383 when the part has thin walls, fine ribs, long flow paths, or a production history of cold shuts and hot cracks. Stay with A380 when geometry is conventional, multi-country sourcing matters, and your foundry already runs a stable process on it. When the decision is genuinely close, let casting simulation and a trial shot settle it.
A short checklist for your next RFQ:
- Walls below roughly 2 mm, or long thin ribs: specify A383 or ADC12.
- Hot cracks near bosses or thick-to-thin transitions: switch to A383 before touching the mold.
- Standard housings and brackets with multi-region sourcing: stay with A380.
- Leak-tight parts that still fail with A383: evaluate A413 with vacuum assist.
- Decorative anodizing as a hard requirement: neither alloy is ideal; review A360 or a wrought grade with your supplier.
Meituo casts both alloys across 20 cold chamber machines from 160T to 1650T, with annual aluminum die casting capacity near 10,000 tons. Incoming ingot lots are verified by fluorescence spectrometer before melting, so the chemistry on your material certificate matches what actually goes into the furnace, and every new mold is proven out with flow simulation before sampling.
The short version: A380 is the default, and A383 aluminum is the problem solver for thin walls and cracking-prone geometries. Define the geometry problem first, then pick the alloy. If you are weighing the two for a live project, send us the part file for a free DFM review and we will recommend the alloy, gate design, and process window together.
