Aluminum Solution Heat Treatment

Solution annealing on aluminum is done to redistribute the alloying elements evenly in the matrix and reset the base hardness for subsequent age hardening. The part is fully heated to solution temperature and then must be quenched quickly so the alloying elements are frozen in solid solution. If you delay this or miss the temperature, you won't get proper values during aging and the material will stay soft. After welding, this is often necessary because the heat input disrupts the microstructure in the weld and HAZ.