Aluminium casting alloys are designated under several standards: the Japanese ADC series, the British LM series, American grades (such as A356 and A380) and European designations such as AlSi9Cu3. This article reviews the most widely used alloys and what each is used for.
ADC12 and ADC10: the most widely used die-casting alloys
With about 9.6–12% silicon and 1.5–3.5% copper, ADC12 is the most widely used high-pressure die-casting alloy. Its high fluidity, dimensional stability and good machinability suit it to gearbox housings, engine brackets, home appliance parts and power tool bodies. ADC10, with more copper, is slightly stronger.
A380 and LM24
A380 (7.5–9.5% Si and 3–4% Cu) and its British equivalent LM24 are all-purpose die-casting alloys that offer a good balance of castability, strength and cost, and are used in automotive parts, housings and industrial components.
A356 and A357: strength and ductility
A356 (about 7% Si and 0.3% Mg) has high strength and ductility after T6 heat treatment and is used for aluminium wheels and automotive chassis and suspension parts. Grade A356.2, with very low iron (below 0.12%), is chosen for critical safety parts. A357, with more magnesium, is stronger still.
LM6 and A413: the best castability
With a near-eutectic composition (10–13% Si), these alloys have the highest fluidity. Thin-walled parts, pressure-tight parts, pump housings and marine components are typical uses.
LM13, LM26 and LM28: piston alloys
Low thermal expansion and high wear resistance make these alloys suitable for pistons and engine parts that work at high temperatures. LM28, with 17–20% silicon, is a hypereutectic alloy.
LM2, LM4, LM21 and LM27: general engineering
These grades are used for gravity, sand and die casting of general engineering parts, manifolds and automotive components, and, depending on their copper and silicon content, offer different balances of strength and castability.
AS grades (French standard)
Grades such as AS7G (roughly equivalent to A356), AS9U3 (roughly equivalent to AlSi9Cu3) and AS5U3 are common among Iranian parts makers, and Almas Aluminium produces them too.
Summary
When choosing an alloy, consider the casting process, whether heat treatment is needed, the wall thickness and the part's working environment. The chemical composition of every grade Almas produces is in the composition table. For advice and an aluminium ingot quote, contact the sales team.