What is A356 Aluminum - A356 Aluminum Composition, Properties, Uses & A356 Aluminum vs 6061
In casting alloys collection, A356 aluminum is a typical material for aircraft applications. Unlike wrought alloys, cast aluminum has a different designation system. In this article, we’ll focus on A356 (A356.0) aluminum alloy, explain what is A356 aluminum, list its composition, properties, tempers, and uses, as well as 6061 vs A356. For superior quality A356 aluminum casting parts, we’re capable of aluminum die casting for a wide range of industries.
What is A356 Aluminum? - Introduction to A356 Aluminum Names and Properties
A356 is a type of aluminum alloy for casting. In cast aluminum alloy designation system, there are 1xx.x, 2xx.x, 3xx.x, 4xx.x, 5xx.x, 6xx.x, 7xx.x, 8xx.x, and 9xx.x series. The 3xx.x series means the principal alloying element is silicon plus copper and/or magnesium. The second and third digits reveal the minimum percentage of aluminum. The number following the decimal point indicates whether the alloy is a casting (.0) or an ingot (.1 or .2). The A in front of an alloy designation denotes a higher purity version of the chemical composition. A356.0 is the designation for this material from Aluminum Association (AA). In UNS standard, it is A13560 and the SAE designation is 336. A356 aluminum die casting alloy has good casting and machining performance, suitable for use in aircraft, pump housings, impellers, high-velocity blowers, and other structural castings that require high strength. A356 aluminum often used to manufacture intricate and complex aluminum castings, which provides lightweight, pressure tightness and great mechanical properties. Sometimes, A356 used as an alternative for 6061 aluminum.
A356 Aluminum Specification
A356 Chemical Composition (wt%)
Si (Silicon): 6.5 – 7.5%
Mg (Magnesium): 0.25 – 0.45%
Fe (Iron): ≤ 0.20%
Cu (Copper): ≤ 0.20%
Mn (Manganese): ≤ 0.10%
Zn (Zinc): ≤ 0.10%
Ti (Titanium): ≤ 0.20%
Other each: ≤ 0.05%
Other total: ≤ 0.15%
Al (Aluminum): Balance
Mechanical Properties (typical, heat-treated A356-T6)
Tensile Strength: ~310 MPa (45 ksi)
Yield Strength: ~230 MPa (33 ksi)
Elongation: 3–6% (depending on casting quality)
Hardness: ~75 HB
Density: ~2.68 g/cm³
Key Characteristics
Excellent corrosion resistance (better than many Al casting alloys).
Good weldability and machinability.
High strength-to-weight ratio.
Can be heat-treated (commonly T6: solution heat treated + artificially aged).
Standards & Designations
ASTM: A356.0
AA (Aluminum Association): A356
Similar alloys: A357 (slightly higher Mg for increased strength)
A356 (A356.0) Aluminum Composition
– Cu: 0.20% (max)
– Mg: 0.25 to 0.45%
– Mn: 0.10% (max)
– Si: 6.5 to 7.5%
– Fe: 0.20% (max)
– Zn: 0.10% (max)
– Ti: 0.20% (max)
– Others (total): 0.15% (max)
– Al: balance
A356 (A356.0) Aluminum Properties - Physical and Mechanical Properties of A356 Aluminum
The a356 material properties including 5 variations (tempers), they are A356.0-F, A356.0-T6, A356.0-T51, A356.0-T61, and A356.0-T71. T6 heat treatment of a356 alloy castings offers improved hardness and other mechanical properties. Here we create a chart that shows some properties of A356.0 aluminum in the T51, T6, and T71 temper.
A356.0 Aluminum Uses/Applications
The typical applications of a356 aluminium including aircraft structures and engine controls, nuclear energy installations, high strength airframe and space frame structural parts, machine parts, truck chassis parts, high-velocity blowers, and impellers, and other applications where high-strength permanent mold or investment castings are required
A356 Aluminum vs 6061
Why a356 aluminum alloy can be used as a substitute for 6061 aluminum? Let’s take a look at the comparison between 6061-T6 aluminum and A356.0 aluminum. They have 94% of their average alloy composition in common. Check out the difference between 6061 and A356 properties.
A356 vs 6061, What's the Difference?
Processing Method
A356 → Casting alloy (Al–Si–Mg family). Poured into molds, excellent for complex shapes.
6061 → Wrought alloy (Al–Mg–Si family). Rolled, extruded, or forged, ideal for bars, plates, and structural sections.
Chemical Composition
A356: ~7% Si, ~0.3% Mg, trace Fe/Cu, balance Al.
6061: ~1% Mg, ~0.6% Si, ~0.3% Cu, ~0.2% Cr, balance Al.
Strengths
A356
Excellent corrosion resistance (better in marine/saltwater than 6061).
Castable → Can form complex geometries (engine blocks, wheels, housings).
Lighter Si content improves fluidity in casting.
6061
Higher toughness and ductility.
Better fatigue resistance.
Easier to machine and form (extrusions, plates).
More consistent properties (less porosity than cast alloys).
Applications
A356: Automotive wheels, aerospace castings, marine components, pump housings.
6061: Structural aerospace parts, frames, pipelines, pressure vessels, machining stock.
Which is Better?
It depends on how you’ll use it:
Choose A356 if → you need cast parts with complex shapes, good corrosion resistance, and cost-effective manufacturing in bulk.
Choose 6061 if → you need machined/extruded parts, higher ductility, toughness, or precision with fewer casting defects.
A356 Aluminum Equivalent
A356 aluminum is a casting alloy in the Al–Si–Mg family, so its equivalents are usually other casting alloys with similar chemistry and properties rather than wrought alloys (like 6061). Here are the closest equivalents:
International Equivalents of A356 Aluminum
ASTM / SAE: A356.0
AA (Aluminum Association): A356
UNS Number: A13560
ISO: AlSi7Mg0.3
DIN / EN (Europe): EN AC-42100 (AlSi7Mg0.3)
JIS (Japan): AC4CH
BS (UK): LM25