Four requirements decide the alloy
For a pressure-tight part, start from what the casting must survive, not from a familiar grade name. Four requirements usually decide: castability (enough fluidity to fill the walls without defects), heat treatability (whether T6 is needed), corrosion behaviour in the service medium, and machinability of the sealing features. Then check the alloy against the route: a die casting alloy and a squeeze casting alloy are chosen for different reasons.
Alloys we cast, by what they are chosen for
| Alloy | Route | Typical reason for selection |
|---|---|---|
| A356 / A356.2 | Squeeze casting | Heat-treatable to T6; strength with ductility; low copper for corrosion; weldable |
| A360 | Die casting | Better corrosion resistance and pressure tightness than A380 |
| A413 | Die casting | Excellent castability and pressure tightness where lower ductility is acceptable |
| A319 / A319S | Die casting | Machined parts where sealing or pressure tightness matters |
| A380 / A383 | Die casting, squeeze | General purpose; A383 fills thin or complex sections more easily |
| ADC10 / ADC12 | Die casting | JIS grades for housings, covers and general parts |
| AlSi10Mg | Die casting, squeeze | Low copper; fluidity; heat-treatable on a qualified route |
| AlSi9Mg / AlSi7Mg | Die casting, squeeze | Heat-treatable Al-Si-Mg family |
| AlSi9Cu3 | Die casting, squeeze | European general-purpose die casting alloy |
| Zamak 2, 3, 5, 7; ZA-8, ZA-12, ZA-27 | Zinc die casting | Thin walls, fine detail, as-cast surface; ZA grades for strength and wear |
What pressure tightness depends on
An alloy name does not make a part pressure-tight. Leak paths come from connected porosity, shrinkage at hot spots, cold shuts and machining breakouts. The alloy contributes through its freezing range and fluidity: alloys near the eutectic, such as A413 and the AlSi10–12 family, feed well in die casting; A356 relies on the squeeze route and pressure during solidification. The route, the wall design and the location of sealing faces matter as much as the grade.
Copper, corrosion and the medium
Copper raises strength in die casting alloys (A380, AlSi9Cu3, ADC12) but lowers corrosion resistance. For parts exposed to water, coolant or outdoor service, the low-copper alloys (A356, A360, AlSi10Mg) are evaluated first. State the medium and environment in the RFQ; the alloy follows.
For equivalents across EN, ASTM, JIS and GB, see AlSi10Mg equivalent material and the rest of the substitution checklist.
How composition is verified
- Incoming ingot checked before melting
- Melt verified by optical emission spectrometry, per heat
- Mechanical properties on specimens when the drawing or standard requires them
- Hardness after heat treatment
When the alloy is still open
Send the function, loads, medium, pressure and environment, and say that the material is open. We propose an alloy and route with the reasoning, and you approve the specification before tooling.