A356

Introduction to A356

A356 is a hypoeutectic aluminum-silicon-magnesium alloy widely applied in high-integrity casting scenarios such as aerospace structures, automotive suspensions, and precision enclosures. Comprising approximately 7.0% silicon and 0.3% magnesium, this alloy effectively balances mechanical strength and castability. When artificially aged to T6 condition, A356 achieves tensile strengths up to 310 MPa while maintaining ductility levels above 5%, satisfying many OEM component performance requirements.

As part of the aluminum die casting alloy portfolio, A356 is optimized for applications that demand thin-walled geometry, low porosity, and high dimensional stability. At Neway Die Casting, A356 is processed using controlled solidification and mold temperature systems to reduce hot tearing and maximize material homogeneity.

A356 Chemical Composition

This composition complies with ASTM B26 and ISO 3522 standards for aluminum casting alloys.

Physical Properties of A356 Aluminum Alloy

These physical properties make A356 suitable for heat-dissipating parts like LED housings, compressor covers, and automotive pump casings.

Mechanical Properties (T6 Heat Treatment)

Mechanical characteristics are aligned with the requirements outlined in SAE J452 and AMS 4218 for heat-treated aluminum alloys in structural applications.

Castability of A356

A356 exhibits excellent foundry characteristics, making it one of the most frequently used alloys in precision sand and permanent mold casting:

• High fluidity promotes complete cavity filling in thin sections

• Low solidification shrinkage reduces hot cracking

• Superior feeding characteristics minimize internal porosity

• Excellent compatibility with semi-permanent core inserts and metal chills

In Neway’s metal casting process, A356 is cast using real-time thermal control systems, ensuring predictable microstructure and consistent wall thickness across batches.

Common Applications

A356 is engineered for moderate- to high-load components requiring a combination of light weight, corrosion resistance, and mechanical durability:

• Automotive: Suspension arms, steering knuckles, compressor housings

• Aerospace: Navigation enclosures, fuel system housings

• Marine: Anti-corrosive pump bodies and valve housings

• Energy: Alternator end covers, motor enclosures

• General Industry: Structural brackets, light load-bearing frames

• Rapid prototyping of critical components before production tooling

Machining Challenges and Solutions

Despite its overall machinability, A356 presents specific challenges during high-speed or high-precision machining operations:

• Entrapped gases and shrinkage porosity may cause tool chatter or insert failure

• High silicon content (eutectic structure) accelerates cutting tool wear

• Thin-walled castings may experience stress warping post-fixturing

To ensure geometric accuracy, post-machining services at Neway incorporate:

• CNC path optimization tailored for Si-rich microstructures

• PCD or TiAlN-coated cutting tools to prolong service life

• Secondary heat treatment (stress relief) prior to finishing

• CMM-based in-process inspection ensuring ±0.05 mm tolerances

Surface Treatment Compatibility

A356 offers excellent substrate behavior for surface finishing methods, enhancing both durability and cosmetic value:

• Anodizing increases surface hardness and corrosion resistance

• Powder coating adds abrasion resistance and UV protection

• Painting and polishing achieve commercial-grade aesthetic quality

These treatments help extend the life of parts in marine, outdoor, and corrosive chemical environments.

FAQs

1. What heat treatments are commonly used for A356 aluminum castings?

2. How does A356 compare to A319 or A380 in terms of mechanical performance?

3. Is A356 suitable for thin-wall complex part designs?

4. What is the typical porosity level for A356 sand cast parts?

5. Can A356 parts be TIG or MIG welded after casting?