aluminum profile materials 31 and 12 are all three materials. Brand name: material 22 is an aluminum alloy with 8 zinc as the main alloy element G; material 613 is an aluminum alloy with 3 magnesium and silicon as the main alloy element E and 5 mg, and Si phase 8 as the main alloy element. See GB for details. Table 3a of T 36876-626_ "Variant aluminum and C-aluminum alloy brand indicating square and 8 method"