Steps of solid solution heat treatment of parts

During the solid solution heat treatment, the parts are heated to 1,000 ° F for up to 12 hours.

At this temperature, the hardened elements silicon (Si) and magnesium (Mg) dissolve into aluminum, forming a uniform solid solution. The solid-solution heat treatment also breaks down eutectic Si into smaller pieces, changing the shape from plate to round. This improves the mechanical properties of castings.

Immediately after the solid solution heat treatment, the parts are quenched in water and cooled rapidly to dissolve the Si and Mg in the desired composition. A balance must be struck between rapid cooling (retaining most of the hardened elements) and reduced residual stresses that may cause warping; The higher the temperature of the water bath, the lower the cooling speed, usually using about 160°F of the bath temperature.

The final step is artificial aging, which involves heating the parts for up to 5 hours at about 310°F, or the length of time necessary to process the parts according to their geometry and the necessary mechanical specifications.