Guide
What are the mechanical properties of ADC12 aluminum?
ADC12 is the aluminum-silicon-copper die-casting alloy defined in the Japanese Industrial Standard JIS H 5302, and it has no single official set of mechanical properties. The standard fixes its chemistry but leaves strength, elongation and hardness to agreement between buyer and supplier, which is why the tensile figures you find online do not match each other.
By Saola Manufacturing engineering team · Published · Updated
This guide is for mechanical engineers and sourcing managers who have an ADC12 quote in hand and a strength requirement on the drawing. It covers what the Japanese, European and US documents say about die-casting properties, the typical figures for the nearest US alloys, and how to make a strength requirement enforceable. Composition limits are covered separately in the ADC12 vs A380 guide, so this page does not repeat them.
A note on method. JIS H 5302 is sold by its publisher; the statements below about its content come from the 2006 edition, read through a public transcription, and are quoted as clause references rather than reproduced. No ADC12 strength value is printed on this page, because no primary source we could open publishes one as a requirement.
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Why do published ADC12 tensile values disagree?
They disagree because they were measured on different things: some come from separately cast test bars made under ideal conditions, some from specimens cut out of real castings, and some are copied from A380 or 383 data and relabeled as ADC12. None of them is a guaranteed minimum.
A die-cast test bar is a small, uniform, thin section that fills quickly and freezes fast. That gives it a fine grain, a dense chilled skin and little room for trapped gas. A production housing has thick bosses next to thin walls, long flow paths and gates that freeze at different times, so it carries more porosity and a coarser structure in its heavy sections. A specimen machined out of that housing will almost always test lower than the bar, and elongation drops more than strength does.
The second source of spread is chemistry inside the allowed range. ADC12 permits a band of silicon, copper and iron, and each moves the result. The North American Die Casting Association explains that iron is needed to stop molten aluminum soldering to the die, but that it forms needle- or plate-shaped intermetallic particles that reduce ductility and often act as fracture starting points (NADCA, aluminum alloys). Two lots that both meet the grade can therefore show quite different elongation.
The third source is relabeling: because ADC12 sits between A380 and 383 in chemistry, data sheets often print US typical values under the Japanese name. Read any single ADC12 tensile number as an indication of the alloy family, not a property of your part.
What mechanical properties does JIS H 5302 actually require?
None: the 2006 edition of JIS H 5302 requires the chemical composition of each grade but states that mechanical properties are set by agreement between the parties to the delivery. A quote or mill certificate that says only “ADC12” therefore commits the supplier to chemistry, not to strength.
The quality clause of the standard lists what a die casting must meet: a smooth surface free of harmful cracks and cavities, no repair by welding or plugging without the buyer’s consent, chemistry to the composition table, and mechanical properties by agreement (JIS H 5302:2006, clause 5, public transcription). The annex comparing JIS with the matching international standard, ISO 3522, gives the reason. It records that ISO lists mechanical properties for die castings only as guidance, that those guideline values come from very high-quality separately cast test pieces, and that they cannot be applied to test pieces cut from products. JIS chose to leave both the values and the test method to the buyer and supplier.
For a buyer this is useful to know before the first sample arrives. If the drawing carries a tensile requirement and the purchase order only says “ADC12”, the supplier has met the standard even if a coupon from the part tests low. The requirement has to be written into the order, with the specimen type and the test method, to be enforceable.
What typical properties can you expect from the nearest US alloys?
The closest free, primary data set is NADCA’s material properties table for the US die-casting alloys, which lists typical as-cast values for 380.0, A380.0 and 383.0 measured on separately die-cast specimens. ADC12 falls between A380.0 and 383.0 in chemistry, so treat these columns as a range for the family, not as ADC12 values.
NADCA states in the table heading that the figures are typical values for separately die-cast specimens, not for specimens cut from production die castings (NADCA, Table 4.1). The rows below are copied from that table for the three alloys nearest to ADC12.
| Property | 380.0 | A380.0 | 383.0 |
|---|---|---|---|
| Ultimate tensile strength, ksi (MPa) | 46 (320) | 47 (320) | 45 (310) |
| Tensile yield strength, 0.2% offset, ksi (MPa) | 23 (160) | 23 (160) | 22 (150) |
| Elongation, % in 2 in. (51 mm) | 3.5 | 3.5 | 3.5 |
| Hardness, BHN | 80 | 80 | 75 |
| Shear strength, ksi (MPa) | 28 (190) | 27 (190) | Not listed |
| Fatigue strength, rotary bend, ksi (MPa) | 20 (140) | 20 (140) | 21 (145) |
| Young’s modulus, psi × 106 (GPa) | 10.3 (71) | 10.3 (71) | 10.3 (71) |
| Density, lb/in3 (g/cm3) | 0.099 (2.74) | 0.098 (2.71) | 0.099 (2.74) |
Three things in the table matter for design. First, the strength columns barely move between the three alloys, which supports treating ADC12 as a member of the same family for early sizing. Second, the elongation is low, so these alloys give little warning before they crack; design for stiffness and avoid relying on the part to yield and redistribute load. Third, NADCA’s own footnote says that sample soundness has a great effect on fatigue results and that this causes disagreement among data sources, so the fatigue row deserves the widest safety margin.
None of these documents gives a design allowable. Treat the typical figure as the ceiling of what a good casting reaches, apply your own knockdown for section size and porosity, and confirm with coupons cut from the actual part.
How do properties in a real casting differ from test-bar values?
Properties in a real casting are lower and vary from place to place, because thick sections cool more slowly and hold more porosity than a test bar. The difference is largest in heavy bosses, at the end of long flow paths and anywhere the dense surface skin has been machined away.
The European standard shows the same logic in its structure. EN 1706 specifies mechanical properties for separately cast test pieces, puts the high-pressure die-casting data in an informative annex, and gives a separate informative annex for properties that may be achievable in test pieces taken from a casting (EN 1706:2020+A1:2021, scope and contents). In other words, the European and Japanese standards agree that a die-cast part is not a test bar, and neither turns die-cast figures into requirements.
Heat treatment does not close the gap the way it does for sand or permanent-mold castings. NADCA notes that aluminum die castings are not usually solution heat treated, that low-temperature aging is used for stress relief or dimensional stability, and that a T2 or T5 temper can be applied to improve properties. Die castings are also not generally welded or brazed. Plan the part so that it meets its loads in the as-cast state.
Machining changes the picture as well. The fine-grained chilled layer at the surface is usually the strongest and soundest material in the part; cutting a sealing face or a bore removes it and can open subsurface porosity. Where a machined feature carries load or pressure, keep the stock allowance small and ask for the machined zone to be checked. The CNC milling page describes the post-cast machining work done on cast parts.
How should you call out ADC12 properties on a drawing?
Name the alloy and its standard in full, and if strength matters, add the property, the specimen type and the test method as a separate note that the purchase order references. A bare grade name controls chemistry only.
A workable callout has four parts. The material line names one governing standard, for example “Aluminum alloy ADC12 per JIS H 5302”, or the US or European grade if that is what the design was sized on. EN 1706 gives a model for completeness: its designation clause asks the drawing to carry the standard number, the alloy, the casting process and the temper. The property note then states what is required and on what: separately cast bars poured with the lot, or coupons cut from a named location in the part. The test method is named, with the number of specimens per lot. Finally, the acceptance rule says what happens when a result is low, such as retest, sort or reject.
Where strength is not critical, say so. A note such as “mechanical properties not specified; chemistry per JIS H 5302 to be reported per lot” is honest and avoids a dispute over numbers nobody measured. The RFQ preparation guide covers where these notes go in the package, and the tolerance guide covers the dimensional side of the same drawing.
How do you verify ADC12 properties from an overseas die caster?
Verify chemistry on every lot, and verify mechanical properties only through the test you wrote into the order, on the specimen type you named. Chemistry is the part of ADC12 that the standard actually controls, so it is the cheapest and most reliable check.
Suppliers in Japan, China and Vietnam commonly quote die castings in JIS grades, so an ADC12 quote on a US or European drawing is normal. When you move a die-cast part from one Asian supplier to another, the grade name stays the same but the melt practice, the die design and the gating change, and with them the porosity and the properties of the part. Treat a supplier change as a new first article and repeat the checks below, even when the old supplier’s parts never failed.
Keep the checks in proportion to the risk. For a cover or bracket that is sized by stiffness, lot chemistry and a hardness check are often enough. For a pressure-containing housing or a part that carries a structural load, add radiographic inspection of the critical zones, a leak test where it applies, and coupons cut from the part. Hardness is a quick screen but a weak proof: it tracks strength loosely and says little about elongation or porosity.
Saola sources ADC12 aluminum and Zamak 3 zinc die castings from partner foundries and machines them at its lead CNC plant; finishing is done by partner plants, and the quote names the production site and origin. If your drawing carries a property requirement, send it with the RFQ and name the specimen type, so the test plan is agreed before tooling rather than after the first samples.
Frequently asked
Is there an official tensile strength for ADC12?
No. JIS H 5302 leaves mechanical properties to agreement between buyer and supplier, so any ADC12 tensile figure you see is a typical or test value from some source, not a requirement of the standard.
Can I use A380 data to design an ADC12 part?
For early sizing, yes, as long as you treat the published A380 and 383 figures as typical test-bar values for the family and apply your own margin. For a part sized close to its limit, test coupons from the actual casting.
Can ADC12 be heat treated to raise its strength?
Not in the way wrought or sand-cast alloys are. Die castings are not usually solution heat treated; low-temperature aging tempers such as T5 can be used for stability and some improvement, and should be written on the drawing if required.
Why is ADC12 elongation so low?
High silicon, iron-rich intermetallic particles and die-casting porosity all limit how far the alloy stretches before it breaks. Design ADC12 parts for stiffness and avoid features that depend on the part bending without cracking.
What should an ADC12 material certificate show?
The lot or heat number, the measured chemistry against the JIS H 5302 limits, and any mechanical test results only if your order required them, with the specimen type stated.
Sources
- JIS H 5302, Aluminum alloy die castings, clause 5 and Annex 2 (public transcription), Japanese Industrial Standards Committee, 2006 edition
- Table 4.1, Die Casting Alloys Material Properties Comparison, NADCA, Product Design for Die Casting (E606), 2008 chart
- Aluminum Alloys (iron, heat treatment and welding), NADCA Design, North American Die Casting Association, accessed September 2026
- EN 1706:2020+A1:2021, castings: chemical composition and mechanical properties (published sample pages: scope, designations, contents), CEN via SIST, 2021