Heat Treatment Process for Aluminum Casting

Generally, the shape of the castings processed by aluminum casting is relatively complex, the thickness is uneven, the grain size is coarse, and the segregation is severe, so it needs to be properly heat treated before it can be used normally. The usual heat treatment processes include annealing, quenching and aging and stabilization.

The purpose of heat treatment of casting aluminum alloys by professional precision casting manufacturers is to eliminate the internal stress of castings; eliminate casting segregation, change the shape of needle-like components in the alloy structure; improve the mechanical properties of aluminum alloys; Function; Improve the machinability of castings.

Annealing: It is carried out in an aluminum alloy annealing furnace, and the room temperature is heated to 280-300 °C. According to the thickness of the casting, the size of the furnace and the way of placement, the holding time is reasonably confirmed, generally 2-3 hours, and the annealing process can be completed. , and then power off and open the furnace door to scatter the castings on the cooling table for air cooling, and it is strictly forbidden to stack them.

Quenching and aging: Considering that the cast aluminum alloy contains more impurities, the arrangement is uneven and the eutectic arrangement with low melting point will appear, so the heating temperature for quenching is lower than the solubility temperature. Quenching heating temperature is generally 500 ~ 535 ℃, lower than 350 ℃ furnace, it should be heated slowly, the holding time is 2 ~ 20h, considering to prevent the deformation and cracking of complex parts, cast aluminum alloy should be cooled in 80 ~ 100 ℃ water.

When selecting the quenching temperature, the influence of the above factors should be considered to avoid overheating or overburning. The intention and effect of aging are divided into two types: complete aging and incomplete aging, which should be reasonably selected according to the specific requirements of the parts, and will not be repeated here. After quenching, the parts can be stabilized and tempered in the electric furnace to replace the aging treatment. Usually, the tempering temperature is higher than the artificial aging temperature, but close to the working temperature of the casting, and air-cooled after the heat preservation.