A356 Aluminium Alloy Ingot

A356 aluminium alloy ingots are defined by a siliconrich AlSiMg composition designed for excellent castability, good strength after heat treatment, and controlled impurities. The core answer is that A356 contains ~6.57.5% Si, 0.250.45% Mg, very low Fe/Cu/Mn/Zn/Ti, and the balance aluminium.

Chemical Composition of A356 Aluminium Alloy

Typical ranges (wt.%):

• Aluminium (Al) Balance (~91.192%)
• Silicon (Si) 6.57.5%
• Magnesium (Mg) 0.250.45%
• Iron (Fe) 0.20%
• Copper (Cu) 0.20%
• Manganese (Mn) 0.10%
• Zinc (Zn) 0.10%
• Titanium (Ti) 0.20%
• Other elements (each) 0.05%
• Other elements (total) 0.15%
  
  

Why These Elements Matter

• Silicon improves fluidity, reduces shrinkage, and enhances castability.
• Magnesium enables precipitation hardening (MgSi), crucial for T5/T6 strength.
• Iron is controlled tightly to avoid brittle intermetallics.
• Copper slightly increases strength but may reduce corrosion resistance.
• Titanium acts as a grain refiner for better microstructure.
  
  

Grade Variants (A356.0 / A356.1 / A356.2)

• A356.0 Standard commercial grade for sand/permanentmold casting.
• A356.1 Higher purity, lower Fe; better mechanical properties.
• A356.2 Highest purity; used for premium, highintegrity castings.

Quick Comparison Table

Practical Insight for Metallurgy & Casting

The key control parameters for A356 ingots are:

• SiMg balance determines T6 response and final strength.
• Fe control critical for avoiding AlFeSi platelets that reduce ductility.
• Ti additions improve grain refinement, especially in sand casting.
• Hydrogen & porosity control essential for fatiguecritical components.