A356.0 Cast Aluminum

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A356.0 is an Al-Si-Mg casting alloy in the Aluminum Association 3xx.x family. Its 6.5–7.5% silicon content provides strong fluidity and feeding behavior for complex castings, while magnesium enables precipitation hardening after solution treatment and aging. Compared with 356.0, A356.0 has a lower iron limit, supporting better ductility and fatigue-sensitive performance when casting quality is controlled. It is widely specified for sand and permanent-mold castings that need low weight, corrosion resistance, pressure integrity, and useful T6-level strength, including wheels, pump bodies, structural housings, and marine components.

Chemical Composition (wt.%)
Chemical Composition wt.%
Element	Min	Max
Silicon	6.5	7.5
Magnesium	0.25	0.45
Iron	—	0.20
Copper	—	0.20
Manganese	—	0.10
Zinc	—	0.10
Titanium	—	0.20
Other elements, total	—	0.15
Aluminum	Balance

Composition notes

Silicon: Registered range.
Magnesium: Registered range.
Other elements, total: Total maximum reported by the source.
Aluminum: Remainder.

Registered composition limits for the A356.0 casting designation. Values are mass percent. The “A” prefix identifies the controlled-purity A356 family; do not substitute A356.1 or A356.2 ingot chemistry for an A356.0 casting specification. “Others” is a total maximum where specified.

Mechanical values are reported temper-specific figures and should not be treated as universal casting design allowables. Actual results depend substantially on mold process, section thickness, melt quality, porosity control, test-bar method, and heat-treatment practice. Physical values are reported as typical values.

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Table of A356.0 Cast Aluminum Properties

Table of A356.0 Cast Aluminum Properties
Physical Properties	Metric
Density	2.68 g/cm³2.68 g/cm³
Mechanical Properties	Metric
Elastic Modulus	70 GPa
Shear Modulus	26 GPa
Ultimate Tensile Strength	19 ksi
Yield Strength	9.5 ksi
Elongation	2 %
Ultimate Tensile Strength	34 ksi
Yield Strength	24 ksi
Elongation	3.5 %
Thermal Properties	Metric
Coefficient of Thermal Expansion	21 µm/m·K
Thermal Conductivity	150 W/m·K
Melting Range	557–613 °C

Test conditions & data notes

Density: Typical reported value.
Elastic Modulus: Typical reported value.
Shear Modulus: Typical reported value.
Coefficient of Thermal Expansion: Typical reported value.
Thermal Conductivity: Typical reported value; source identifies the value for T6.
Melting Range: Reported solidus-to-liquidus range.
Ultimate Tensile Strength: A356.0-F, as-cast.
Yield Strength: A356.0-F, as-cast.
Elongation: A356.0-F, as-cast.
Ultimate Tensile Strength: A356.0-T6.
Yield Strength: A356.0-T6.
Elongation: A356.0-T6.

Material Conditions & Tempers

A356.0 is supplied as-cast or heat treated to obtain the strength–ductility balance required by the casting. T6 is the common structural condition; it uses solution heat treatment, quenching, and artificial aging to develop Mg-Si precipitation strengthening. Verify required properties against the applicable casting specification and the required test-bar location.

Condition	Tensile Strength	Yield / Proof Strength	Notes
F	19 ksi	9.5 ksi	As-cast condition without a special thermal treatment. Reported elongation: 2%.
T51	26 ksi	16 ksi	Artificially aged condition used where a moderate strength increase and dimensional stability are desired. Reported elongation: 3%.
T6	34 ksi	24 ksi	Solution heat treated, quenched, and artificially aged; commonly selected for higher-strength structural castings. Reported elongation: 3.5%.
T71	31 ksi	18 ksi	Overaged or stabilized condition that trades some peak strength for more stable properties. Reported elongation: 2%.

Advantages & Limitations

Advantages	Limitations
Excellent casting fluidity from the Al-Si chemistry supports intricate geometry, thin sections, and near-net-shape production. Magnesium provides a strong response to T6 precipitation hardening, making A356.0 suitable for lightweight structural castings. The 0.20% maximum iron limit is lower than for 356.0 and helps preserve ductility and fatigue performance when melt cleanliness and solidification are well controlled. Low copper content supports good general corrosion resistance, useful for outdoor, marine, pump, and fluid-handling castings. Thermal conductivity is useful in heat-dissipating housings, tooling, and engine-related cast components. A356.0 is generally practical to machine after heat treatment and can be weld repaired, subject to procedure qualification and post-weld property requirements.	Mechanical properties are highly dependent on porosity, oxide inclusions, microstructure, section thickness, casting route, and the heat-treatment cycle. Welding locally removes the T6 temper; a welded component may require re-heat treatment or acceptance of lower heat-affected-zone strength. The alloy is not normally the preferred choice for high-pressure die casting, where higher-iron alloys are commonly used to reduce die soldering. As a cast alloy, it has lower and more variable elongation than many wrought aluminum products; fatigue-critical designs require casting-quality control and application-specific validation. Quench distortion and residual stress can occur during T6 processing, particularly in thin, asymmetric, or tightly toleranced castings.

Advantages

Limitations

Excellent casting fluidity from the Al-Si chemistry supports intricate geometry, thin sections, and near-net-shape production.
Magnesium provides a strong response to T6 precipitation hardening, making A356.0 suitable for lightweight structural castings.
The 0.20% maximum iron limit is lower than for 356.0 and helps preserve ductility and fatigue performance when melt cleanliness and solidification are well controlled.
Low copper content supports good general corrosion resistance, useful for outdoor, marine, pump, and fluid-handling castings.
Thermal conductivity is useful in heat-dissipating housings, tooling, and engine-related cast components.
A356.0 is generally practical to machine after heat treatment and can be weld repaired, subject to procedure qualification and post-weld property requirements.

Mechanical properties are highly dependent on porosity, oxide inclusions, microstructure, section thickness, casting route, and the heat-treatment cycle.
Welding locally removes the T6 temper; a welded component may require re-heat treatment or acceptance of lower heat-affected-zone strength.
The alloy is not normally the preferred choice for high-pressure die casting, where higher-iron alloys are commonly used to reduce die soldering.
As a cast alloy, it has lower and more variable elongation than many wrought aluminum products; fatigue-critical designs require casting-quality control and application-specific validation.
Quench distortion and residual stress can occur during T6 processing, particularly in thin, asymmetric, or tightly toleranced castings.

Processing & Fabrication

Process	Description
Sand casting	A356.0 is commonly poured into sand molds for complex or lower-volume castings. Provide adequate feeding, controlled gating, degassing, and filtration to limit hydrogen porosity, oxide films, and shrinkage.
Permanent-mold casting	Permanent and semi-permanent molds can provide a finer, more consistent structure than sand casting for suitable shapes. Mechanical requirements must still be specified for the actual mold process and section thickness.
T6 heat treatment	A reported T6 sequence uses solution treatment at 535–540 °C for up to 12 hours, followed by quenching and artificial aging. Exact time, quench practice, and aging cycle must be established for casting section and governing specification.
Machining	Machine after stabilization or final heat treatment where possible. Leave appropriate machining allowance, especially around parting lines, cores, and regions susceptible to local distortion.
Welding and repair	Weld repair can be practical for qualified castings, but the local thermal cycle reduces precipitation-hardened strength. Define permissible repair areas, inspection method, and any required post-weld heat treatment before production.

Applications

A356.0 is selected when a casting must combine shape complexity with low mass and useful heat-treated strength. The alloy is particularly appropriate where corrosion resistance, pressure integrity, thermal transport, or cyclic loading are important, provided the foundry process and inspection level match the service risk.

Automotive wheels and suspension-related castings: Low density and T6 response support high strength-to-weight performance; the controlled iron limit is beneficial for ductility and fatigue-sensitive designs.
Pump housings, impellers, and valve bodies: Good castability enables internal passages and complex hydraulic geometry, while corrosion resistance and potential pressure tightness suit fluid-handling hardware.
Aerospace and defense housings: The alloy can provide lightweight, intricate structural forms with heat-treated strength when produced to appropriately controlled casting-quality requirements.
Marine fittings and equipment housings: Low copper content supports good corrosion resistance for marine exposure when suitable design, finishing, and galvanic-corrosion controls are used.
Engine, drivetrain, and industrial equipment components: A356.0 combines thermal conductivity, low mass, and castability for brackets, covers, housings, and heat-managing components.
Rotational-molding and thermal tooling: The alloy’s castability and thermal conductivity are useful for complex tooling that benefits from effective heat transfer.

Standards & Designations

Designation	Value	Description
Aluminum Association	A356.0	Casting-alloy designation in the 3xx.x Al-Si-Mg family; the .0 suffix identifies the casting form.
UNS	A13560	Common Unified Numbering System designation associated with A356.0.
ASTM	ASTM B26/B26M	Specification commonly referenced for aluminum-alloy sand castings; confirm alloy, temper, test requirements, and applicable revision.
ASTM	ASTM B108/B108M	Specification commonly referenced for permanent-mold aluminum-alloy castings; confirm alloy, temper, test requirements, and applicable revision.
EN	EN AC-42100 / AlSi7Mg0.3	Commonly cited closest European designation; equivalence should be confirmed against the full chemistry and property requirements.

Frequently Asked Questions

What is the difference between A356.0 and 356.0 cast aluminum?

Both are Al-Si-Mg casting alloys, but A356.0 is the controlled-purity A variant. In particular, A356.0 limits iron to 0.20% maximum. Lower iron helps reduce brittle iron-bearing phases and is one reason A356.0 is often preferred where ductility and fatigue performance matter.

Why is A356.0-T6 used so often for structural castings?

The T6 treatment solutionizes the casting, quenches it, and artificially ages it to form strengthening Mg-Si precipitates. This produces much higher strength than the as-cast F condition while retaining the shape freedom and low weight of a casting. Final results depend on casting quality, section thickness, and the qualified heat-treatment cycle.

Is A356.0 suitable for high-pressure die casting?

It is generally used for sand, permanent-mold, and investment-type casting routes rather than conventional high-pressure die casting. High-pressure die-casting alloys often use higher iron contents to reduce die soldering, whereas A356.0 deliberately restricts iron to support ductility and heat-treatment response.

References & Data Notes

(n.d.). A356 Aluminum Alloy: Composition, Properties & Applications. https://rotocastmold.com/feeds/blog/a356-0-aluminum-alloy-composition
(n.d.). Everything You Need to Know About A356 Aluminum Alloy: Properties, Applications, Benefits, and Limitations. https://topsbest-precision.com/blog/a356-aluminum-alloy
(n.d.). A356 Aluminum Alloy: Properties, Composition, and Casting Guide. https://www.leclairemfg.com/blog/a356-aluminum-alloy

Composition limits and numerical properties are reproduced from the cited supplied sources. Confirm current governing specification, product form, temper, test-bar method, casting process, and purchaser-specific acceptance criteria before material selection or procurement.