Aluminum alloy processing is to fill molten metal in the mold to obtain aluminum alloys of various shapes of parts. It has the advantages of low density, high specific strength, good corrosion resistance and casting processability, and less restrictions on part structure design. Aluminum alloy processing can be dividedAl-Si and Al-Si-Mg-Cu-based medium-strength alloys; aluminum-copper-based high-strength alloys; aluminum-magnesium-based corrosion-resistant alloys; Al-Re-based hot-strength alloys. Most of the heat treatment is required to achieve the purpose of strengthening the alloy, eliminating the internal stress of the casting, and stabilizing the organization and size of the parts. Aluminum alloy processing is generally used to manufacture beams, gas turbine blades, pump bodies, towers, hubs, intake lips and engine shells. It is also used in the manufacture of automotive cylinder heads, gearboxes and pistons, instrument housings and turbocharger pump bodies. Let's take a look at the heat treatment of aluminum alloy processing.

(1) Annealing: Heat the aluminum alloy processed products to a certain temperature, keep them for a certain time, and then cool them to room temperature at a certain cooling rate. Through the diffusion and migration of atoms, the structure is more uniform and stable, and the internal stress is eliminated, which can greatly improve the plasticity of the material, but the strength will be reduced.

(2) solid solution quenching treatment: the cast aluminum alloy material is heated. Aluminum alloy processing products can be strengthened by heat treatment to a higher temperature and maintained for a certain period of time, so that the second phase or other soluble components in the material are fully dissolved into the aluminum matrix to form a supersaturated solid solution, which can then be cooled down quickly. This supersaturated solid solution remains at room temperature, which is an unstable state. But at this time, the material has high plasticity and can be cold worked or straightened.

(3) Aging: Keep the aluminum alloy processed parts after solid solution quenching at room temperature or higher for a period of time, the unstable supersaturated solid solution will decompose, and the second phase particles will precipitate from the supersaturated solid solution. It is distributed around the alpha (AL) aluminum grains and produces a strengthening effect, called precipitation (precipitation) strengthening.

A, natural aging: some alloys at room temperature can produce precipitation strengthening, called natural aging.

B. Artificial aging: Some aluminum alloy processing products have no obvious precipitation strengthening at room temperature, but have obvious precipitation strengthening effect at higher temperatures, which is called artificial aging.

Artificial aging is divided into under aging and excessive aging.

① Underaging: In order to obtain certain performance of aluminum alloy processing products, the aging temperature is controlled and the aging time is shortened.

② Over-aging: In order to obtain some special properties and better comprehensive properties, aluminum alloy processing is carried out at a higher temperature or for a longer time.

③ Multi-stage aging: In order to obtain some special properties and good comprehensive properties of aluminum alloy processed products, the aging process is divided into several stages. It can be divided into two stages and three aging stages.