For high-pressure die casting of intricate, thin-wall aluminum parts, A383 (also designated ADC12 in JIS) is a deliberate rebalance of the A380 chemistry: silicon is raised to 9.5–11.5% (versus 7.5–9.5% in A380) and copper is cut to 2.0–3.0% (versus 3.0–4.0%), trading roughly 14 MPa of ultimate tensile strength for noticeably better melt fluidity and reduced hot-cracking tendency [S3][S9].
A380 remains the higher-strength benchmark with 324 MPa UTS, 159 MPa yield, and 80 Brinell hardness per the Aluminum Association / NADCA data sheet, and is cited as the most widely specified die-casting alloy globally [S2][S8]. The decision between the two is therefore a section-thickness and complexity call rather than a generic "stronger is better" choice, and that is the lens this reference uses to compare them across chemistry, mechanicals, castability, surface finish, and cost.
Chemistry Comparison: Where A383 Diverges from A380
Both alloys sit in the Al–Si–Cu 3xx.x family, but A383's 9.5–11.5% Si range pushes it close to the eutectic point, which is the metallurgical reason it flows into thinner walls and longer flow paths than A380 [S3][S4]. Copper is reduced to 2.0–3.0% in A383 versus 3.0–4.0% in A380, which lowers strength slightly but improves corrosion resistance and reduces the cracking tendency you see on A380 in constrained geometries [S3][S5]. Magnesium is also bumped to 0.1–0.3% in A383 (≤0.10% in A380 standard, although NADCA permits up to 0.30% Mg in variant E380), allowing some age-hardening response if a T5 or T6 temper is later specified [S3][S5]. Tin is capped lower in A383 (≤0.15% vs ≤0.35%), which is relevant for corrosion-critical electronics housings.
For engineers familiar with the broader aluminum alloy family, the A383 move is the same logic that drives A413 (Si 11.0–13.0%) toward even thinner sections: more silicon, less copper, more melt flow at the cost of as-cast strength. A380, by contrast, leans on copper for its 324 MPa UTS figure that appears in the NADCA Alloy Data table [S8].
Mechanical and Physical Properties Side by Side
The headline mechanical numbers per NADCA / Gabrian: A380 delivers 324 MPa UTS, 159 MPa yield, 80 HB hardness, 3.5% elongation; A383 delivers 310 MPa UTS, 152 MPa yield, 75 HB, 3.5% elongation [S2][S3][S8]. That is a roughly 4–5% strength penalty and a 5 HB hardness drop in exchange for the fluidity benefit. Thermal conductivity is essentially tied at 96 W/m·K for both, with electrical conductivity at 23% IACS, so thermal management housings behave the same regardless of choice [S3].
Elongation at break is identical at 3.5% for both, confirming that neither alloy is a "ductile" choice, and that snap-fit features, threaded bosses, and any post-cast plastic deformation still need generous radii and draft, regardless of whether you pick A380 or A383 [S3]. For deeper context on the casting equipment envelope that processes both alloys, see the aluminum die casting machine reference page.
Castability: Wall Thickness, Fluidity, Hot Tearing
A383 is the consensus pick for very thin-wall and intricate die-cast parts, with multiple sources stating it fills complex molds more reliably than A380, and the JIS ADC12 cross-reference is explicitly highlighted as the common Japanese equivalent used for that reason [S2][S3][S4]. Hotean CNC's alloy-selection guide quantifies the gain as "15–20% better fluidity" for ADC12 (A383) relative to A380 in thicker-section fills, which matters at the end of fill where melt temperature is lowest and shrinkage stress peaks [S7].
A380, by contrast, is described as the "balanced, general-purpose" alloy: it still flows well enough for thin walls in many HPDC cells, but its lower silicon content and higher copper make it more prone to hot tearing on long, thin, constrained features, which is the failure mode A383 was specifically engineered to mitigate [S3][S5][S9]. If a part has uniform 3–4 mm walls with simple geometry, A380 is usually the cheaper and stronger default; if it drops below ~2 mm, has long flow lengths, or includes thin ribs and bosses around a thicker boss, A383 (or ADC12) is the safer production choice [S4][S7].
Surface Finish, Corrosion, and Post-Cast Processing
Both alloys accept the standard die-cast surface-finish stack: shot blasting, vibratory finishing, powder coat, wet paint, chromate conversion, and anodizing with the usual caveats for high-copper Al–Si–Cu alloys. Because A380 has the higher copper (3.0–4.0%), it is marginally more prone to surface staining and corrosion in salt-spray exposure than A383, although the 2.0–3.0% Cu in A383 is still high enough that neither alloy is a "marine-grade" choice without coating [S3][S5].
On the cosmetic side, the lower copper in A383 slightly improves as-cast color uniformity after anodizing, because copper-rich intermetallics are the main cause of dark streaking in Type II anodize on 3xx.x alloys, although both still need process tuning for premium cosmetic Class-A finishes. Neither alloy is weldable in the conventional sense (fusion welding of die-cast Al–Si–Cu is generally avoided), so design for mechanical fastening, snap-fit, or adhesive bonding applies equally to both.
Selection Matrix: A380 vs A383 by Use Case
Casting engineers typically apply this decision matrix: pick A380 when the part is structural or load-bearing, when section thickness stays above ~2.5 mm uniformly, when ultimate tensile strength and hardness drive the design, and when cost per kilogram is the dominant variable, since A380 is the higher-volume, more recycled, and therefore cheaper melt stock [S2][S5][S8]. Pick A383 (ADC12) when wall thickness drops below ~2.0 mm, when flow length is long relative to wall thickness, when hot-tear scrap has been a problem on A380, or when the JIS supply chain (ADC12) is the local availability, which is common across Asian OEM and contract manufacturing [S2][S3][S6].
For applications that sit on the boundary (e.g. 2.0–2.5 mm walls with moderate complexity), pilot runs on both alloys are cheap insurance: in published comparisons A383's fluidity win typically delivers 2–5% fewer misruns and cold-shut rejects, while A380's strength win shows up in burst-pressure and drop-test results on housings [S4][S7]. The trade-off should be quantified in PPAP rather than assumed.
Standards, Designations, and Where the Two Cross-Reference
A380 is designated ANSI/AA A380.0 and is the headline alloy in the NADCA Alloy Data sheets that most North American HPDC cells reference for die-life, shrink, and process-window guidance [S8]. A383 is designated ANSI/AA A383.0, equivalent to JIS ADC12, and is the alloy that bridges U.S. spec language and Japanese supply-chain sourcing for the same thin-wall application space [S3][S4]. Both are covered under ASTM B85 for composition and mechanical-property conformance, and both belong to the 3xx.x casting-alloy family whose behavior on the aluminum die casting machine cell is broadly the same except for the higher melt temperature and slightly longer in-cavity flow time you see on A383 because of the higher silicon charge.
For applications where the design also involves mating metal enclosures, sheet covers, or facade-style housings, the cast A380/A383 part is often paired with metal curtain wall panel architecture or glass curtain wall framing in the same building envelope, although the alloy choice is independent of the facade decision. Where thin-wall die-cast parts also need decorative or protective trim, the door window curtain wall reference covers the integration side; the alloy selection here is governed only by the casting and assembly requirements.
When Neither A380 nor A383 Is the Right Pick
Skip A380 when wall thickness falls below ~2 mm or the part is highly intricate; A383 outperforms it there on fill and hot-tear resistance [S3][S4]. Skip A383 when the part is structural or pressure-tight and the design depends on those last 14 MPa of UTS and the higher 80 HB hardness, or when a low-copper alloy is needed for corrosion-critical service, in which case A360, A413, or K-Alloy/A304 are the documented alternatives [S1][S2][S3]. For very thin-wall die castings where corrosion, ductility, or paint-free finish is required, K-Alloy/A304 cites a 15% better cooling rate versus A380 and eliminates chromating and anodizing steps, so it should be on the shortlist alongside A383 for that specific problem [S1].
For longer-flow, very thin-wall production where the JIS supply chain dominates, ADC12 (A383) is essentially the only practical choice in many Asian contract shops, and any U.S. or EU spec for "A383" will accept ADC12 melt stock with the same ASTM B85 envelope. Confirm melt certification to A383.0 / ADC12 on incoming material certificates before PPAP, since ADC10 (A383's lower-copper sibling at 2.0–4.0% Cu) is sometimes substituted by mistake and will shift both strength and corrosion results. Also useful on the engineering bench: keep a reference to the related why ZA-27 must run on cold chamber die casting machines note if the cell is shared with zinc-family alloys, and to mold base price per kg of steel 2026 cost breakdown when sizing the die budget against alloy savings.