Cast Aluminum alloy
An Aluminum alloy with high castability and fluidity, primarily used for manufacturing complex components via foundry processes.
Aluminum casting is a special case because the material is often porous and contains oils or residues from the casting process. Alloying elements like silicon make the material more fluid, which makes welding tricky. If you hit it with too much heat, the material burns away or it contracts during cooling and cracks. It is important to clean the workpiece thoroughly beforehand and preheat it so that the heat distributes evenly. During welding itself, you have to work calmly and controlled, preferably with TIG and alternating current. Make sure you don't stay in one spot too long, otherwise the structure becomes brittle and you get pores. If you manage that, the weld will hold, but aluminum casting doesn't forgive rough handling.