A356 Aluminum: Properties, Applications, and Advantages

A356 aluminum is one of the most widely used aluminum casting alloys, prized for its combination of strength, corrosion resistance, and excellent castability. Whether in automotive wheels, aerospace housings, or marine components, A356 offers a proven balance of performance and versatility.

At Metal Exchange, we work with manufacturers around the world who rely on high-quality casting alloys like A356 to meet demanding standards. Understanding what makes this alloy special—and how it compares to others—is essential for engineers, buyers, and designers alike.

What Is A356 Aluminum?

A356 is an aluminum-silicon-magnesium alloy developed for casting applications. It’s a refined version of 356 aluminum, with tighter controls on impurities, particularly iron and other trace elements, resulting in improved mechanical properties and consistency.

The typical composition of A356 aluminum includes:

• Silicon (Si): 6.5–7.5%
• Magnesium (Mg): 0.25–0.45%
• Iron (Fe): ≤0.2%
• Copper (Cu): ≤0.2%
• Titanium (Ti): ≤0.2%
• Aluminum (Al): Balance

A356 is used primarily in sand casting, permanent mold casting, and die casting, offering excellent fluidity and resistance to hot cracking.

Key Properties of A356 Aluminum

The alloy’s strength, ductility, and machinability make it a go-to material for structural and non-structural castings. Its performance depends heavily on heat treatment—particularly the T6 condition, which significantly increases mechanical strength.

Here’s a quick comparison of its properties:

A356 vs. 356 Aluminum — What’s the Difference?

While A356 and 356 aluminum are closely related, A356 is produced under stricter metallurgical control. The “A” designation ensures lower iron content and fewer inclusions, which improves ductility and fatigue strength.

• 356: Standard casting alloy suitable for general use
• A356: Refined variant offering better consistency and higher mechanical performance

For applications where safety, precision, and reliability matter—such as aerospace and automotive parts—A356 is the preferred choice.

Common Applications

Thanks to its combination of light weight and strength, A356 is used across a wide range of industries:

• Automotive: wheels, suspension arms, cylinder heads, transmission housings
• Aerospace: non-structural components, brackets, and housings
• Industrial equipment: pump and valve bodies
• Marine: corrosion-resistant fittings and housings
• Energy and power systems: heat exchangers and enclosures

Heat Treatment and Processing

A356 can be heat treated to the T5 or T6 condition, which dramatically increases strength and stability.

• T5: Artificially aged after casting for moderate improvement in strength
• T6: Solution heat treated and artificially aged for maximum mechanical performance

Proper heat treatment not only enhances tensile and yield strength but also improves machinability and dimensional stability—critical for high-precision castings.

Machinability and Finishing

After heat treatment, A356 aluminum machines exceptionally well. Its uniform microstructure allows for tight-tolerance machining, and it responds favorably to:

• Anodizing (for corrosion protection)
• Powder coating (for color and wear resistance)
• Polishing (for aesthetic or aerodynamic applications)

These finishing options make it suitable for components that need both performance and appearance.

Advantages and Limitations

Advantages:

• Excellent castability
• High strength-to-weight ratio
• Great corrosion resistance
• Excellent machinability and weldability
• Suitable for complex shapes and thin-wall designs

Limitations:

• Loses strength at elevated temperatures
• Requires controlled heat treatment for optimal properties
• Shrinkage defects possible if not properly cast

A356 Aluminum in the Global Supply Chain

At Metal Exchange, we supply and trade high-quality aluminum alloys like A356 as part of our comprehensive global supply chain. From primary foundry alloys to recycled materials, we help our customers manage every aspect of sourcing, logistics, and risk management.

Learn more about our related capabilities:

• Recycled Materials
• Primary Foundry Alloys

Our team supports manufacturers with expertise in casting alloys, processing, and sustainability—ensuring every customer has the right material for their needs.