Self-hardening (naturally hard) aluminumdie casting alloy with low iron and high zinc content for die castings with demanding requirements in terms of strength and polishability. An overview of the chemical composition and properties of this alloy are given in Tables 1 and 2.
The alloy type Al Zn10Si8Mg
One way to achieve the highest strength properties while sparing the heat treatment is by using self-hardening or naturally hard materials (s. Hardening). The main alloy used for this in die casting is Al Zn10Si8Mg. For this alloy type, the mechanical properties are achieved after storage for around 7 to 10 days at room temperature.
The die casting alloy achieves the highest values for tensile strength in its self-hardened state and it is especially worth noting the high 0.2% yield strength, however, the low ductility limits the areas where this alloy can be used slightly. Due to the very high zinc content, the alloy has a slightly higher tendency to corrode than AlSi alloys, meaning that a protective coating is recommended. The die casting alloy’s slightly higher iron content is compensated for by a balanced addition of manganese.
The material can be processed brilliantly by machine and can be polished well mechanically. A certain tendency to stress corrosion and contact corrosion muss be observed on a case-by-case basis.
Ductile die casting alloys
Heat treatment of hardenable aluminium alloys