Aluminum Precipitation Hardening

Precipitation hardening works like this: you anneal the material to soften it and then hold it at a certain temperature so that fine particles form in the structure. These make the part really strong. When welding such alloys, you have to be careful that the heat at the weld destroys this fine structure again – the zone next to it becomes softer and loses strength. If you re-age the component completely after welding, you get the original values back.