T-6 HEAT TREATMENT = 30% STRENGTH INCREASE
All cast and forged aluminium must be heat treated following casting or forging to give final strength and hardness to the material. The exact process varies between Cast and Forged, but broadly there are two stages to the treatment.
The cast or forged piece is heated to around 900degF for 9-10 hours. This causes the copper in the aluminium alloy to dissolve into the aluminium, creating a what is called a “Single Phase Alloy.” The piece is then cooled rapidly by “quenching” it in water, which prevents the copper reconstituting within the alloy, thus keeping the alloy “locked” in the “Single Phase Alloy” state.
Following quenching, the piece is heated to a relatively low temperature – around 350degF – for 10 hours, then allowed to cool slowly in air. During this phase, the copper and alumnium (which were thoroughly dissolved and “locked” together in the Quenching Phase) combine to form copper aluminium crystals, CuAl2. It is these crystals that give the alloy (and the piece) it’s strength.
The tricky part is to control the size of the CuAl2 crystals. For best results, the crystals are kept very small to ensure conformity within the cystal structure of the alumnium. Crystal size is carefully controlled by heating and cooling temperatures and times to give the highest strength possible from the treatment.
All our cast and forged trucks use the T-6 process to add strength to the raw aluminium.