Let us know the aluminum casting parts from the view of the strength properties.
Normally a rough subdivision into four groups is practical:
“strong and ductile”
The most important age-hardenable casting alloys belong to this group. By means of different kinds of heat treatment, their properties can be adjusted either in favors of high tensile strength or high elongation.
Some casting alloys are used for highgrade construction components, especially for critical parts.
“hard” The casting alloys of this group must display a certain tensile strength and hardness without particular requirements being placed on the metal’s elongation.
First of all, Al SiCu alloys belong to this group. Due to their Cu, Mg and Zn content, these casting alloys experience a certain amount of self-hardening after casting (approx. 1 week). These alloys are particularly important for pressure die casting since it is in pressure die casting – except for special processes such as vacuum die casting – that process- induced structural defects occur, preventing high elongation values. Due to its particularly strong self-hardening characteristics, the Autodur casting alloy represents a special case allowing hardness values of approx. 100 HB and a corresponding strength – albeit at very low ductility – in all casting processes.
Hypereutectic AlSi casting alloys such as Al Si18CuNiMg and Al Si17Cu4Mg, for example, which display particularly high wear resistance due to their high silicon content, can also be classified in this group.
Casting alloys which display particularly high ductility, e.g. Silumin-Kappa
(Al Si11Mg), come under this general heading. This casting alloy is frequently used for the manufacture of automobile wheels.
In this particular application, a high elongation value is required for safety reasons.
“other” Casting alloys for more decorative purposes with lower strength properties, e.g.
Al Mg3, belong to this category.