A356 Aluminum Casting Alloy

AA A356.0 / T6. A356 is a premium Al-Si-Mg casting alloy that is heat-treatable to T6 for high strength, ductility and leak-tightness — the go-to for structural gravity and sand castings.

Chemical composition (nominal wt %)

Element	%
Silicon (Si)	6.5–7.5
Magnesium (Mg)	0.25–0.45
Iron (Fe)	≤0.20
Copper (Cu)	≤0.20

Mechanical properties

Property	Value
Tensile strength (T6)	234–262 MPa (34–38 ksi)
Yield strength (T6)	165–185 MPa
Elongation (T6)	3.5–5%
Hardness	70–80 HB

Density: 2.68 g/cm³ · Heat treatment: Heat-treatable: T6 (solution treat + artificial age) for peak strength; T5/F also used.

Cross-standard equivalents

Standard	Equivalent grade
JIS	AC4C
EN AC	EN AC-42000 (AlSi7Mg0.3)
GB	ZL101 / ZL101A

Equivalents by nominal class — confirm exact chemistry & spec for critical parts.

Typical applications

Automotive wheels & knuckles
Structural & aerospace castings
Pressure-tight / leak-free housings
Valve bodies

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FAQ

What is the difference between A356 and A380?

A356 (Al-Si-Mg) is heat-treatable with higher ductility and leak-tightness for structural gravity/sand castings; A380 (Al-Si-Cu) is a die-casting alloy with higher as-cast strength but no heat treatment and lower corrosion resistance.