The casting alloy naming system is based on the 3-digit plus decimal designation xxx.x (i.e. 356.0). The first digit (Xxx.x) indicates the primary alloying element added to the aluminum alloy.
The second and third numbers (xXX.x) are arbitrary numbers used to designate a specific alloy in the series. The number after the decimal point indicates whether the alloy is a casting (.0) or an ingot (.1 or .2). Capital letter prefixes indicate modifications to a specific alloy.
For example, Alloy - A356.0, a capital A (Axxx.x) indicates a modification to Alloy 356.0. The number 3 (A3xx.x) indicates that it belongs to the silicon plus copper and/or magnesium family. 56 (Ax56.0) means the alloy is in the 3xx.x series, and .0 (Axxx.0) means its final shape is a casting, not an ingot.
