Designation System for Casting Alloys

Casting aluminium and aluminium alloys are primarily intended for the production of castings by solidification of the molten alloy in a mould.

The properties of castings are related to the composition of the castings alloy, but also significantly by the type of mould and mould filling processes, i.e. the casting processes employed. Casting alloys are tailored to the casting process.

Cast aluminum is a type of aluminum alloy with casting characteristics. Wrought aluminum, on the other hand, is ideal for shaping and machining after heat treatment.

Contrary to the international systems of wrought aluminium alloy designation (AA, ISO, CEN), the designation systems for casting alloys and castings differ significantly.

Specifically, the AA system defines 8 groups of casting alloys, whereas the EN system only differentiates between 4 alloy groups and excludes the tin containing bearing alloys.

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Designation system for casting alloys – EN 1780

The EN designation system for casting alloy composition is made up of the following:

• EN for European standard

• Letter A for aluminium

• Letter C for casting

• Alloy composition is specified either by

  • numericals (5 digits) or

  • by chemical symbols, followed by a letter for the casting process and possibly by a letter and/or digit(s) for temper designation

Example: EN AC-42000KT6 (alloy Al 7%SiMg for chill or permanent mould casting, aged to T6 temper)

The EN designation system by chemical symbols for casting alloy composition is made up of the following:

• Al followed by a space

• Symbol of the major alloying element usually followed by the percentage of mass

• Other alloying elements (max. 4 elements) in descending order; if the mass fractions are the same, in alphabetical order

• In case of similar composition, the difference is made by:
  

  • Stating the nominal contents

  • Example: EN AC-Al Si7Mg0.3, EN AC-Al Si7Mg0.6 or

  • Stating the impurities in brackets

  • Example: EN AC-Al Si10Mg(Cu)
    

Definition of Casting Alloy Groups	First Digit	Second Digit	Chemical
Copper (Cu)	2XXXX	21XXX	AlCu
Silicon (Si)	4XXXX	41XXX	AlSiMgTi
		42XXX	AlSi7Mg
		43XXX	AlSi10Mg
		44XXX	AlSi
		45XXX	AlSi5Cu
		46XXX	AlSi9Cu
		47XXX	AlSi(Cu)
		48XXX	AlSiCuNiMg
Magnesium (Mg)	5XXXX	51XXX	AlMg
Zinc (Zn)	7XXXX	71XXX	AlZnMg

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Designation System for Alloy Castings According to American Standard

Cast Aluminium and Aluminium Alloy Designation System (ANSI H35.1(M)-1997) uses a 4 digit numerical designation

The 1st digit identifies the alloy group. The 2nd two digits determine the alloy or indicate the aluminium purity. The last digit - separated by a decimal point - indicates the product form, i.e. castings (0) or ingot (1, 2). A modification of the original alloy or impurity limits is indicated by a serial letter before the numerical designation.

Example: A356.0 (AlSi7Mg0.3)

Definition of Casting Alloy Groups	Groups
Aluminum, 99 percent and greater Aluminium alloys grouped by major alloying elements	1XX.X
Copper (Cu)	2XX.X
Silicon (Si), with added copper and-or magnesium	3XX.X
Silicon (Si)	4XX.X
Magnesium (Mg)	5XX.X
Zinc (Zn)	7XX.X
Tin (Sn)	8XX.X
Other Elements	9XX.X