1, annealing treatment. After the casting is heated to a higher temperature (about 300℃) and kept for a certain time, the process of cooling with the furnace is called annealing. Annealing treatment can eliminate the internal stress of castings, stabilize the size of castings, reduce deformation and increase the plasticity of castings.
2. Solution treatment. Heat the casting to the highest possible temperature (close to the melting point of * * * crystal), and then keep the temperature for a long time and then cool it quickly, so that the strengthening components can be dissolved in aluminum to the maximum extent. This process of fixed preservation at room temperature is called solution treatment, commonly known as quenching. Solution treatment can improve the strength and plasticity of castings and the corrosion resistance of alloys.
3. aging treatment. The process of heating the casting after solution treatment to a certain temperature, keeping the temperature for a certain time, and then taking it out of the furnace for air cooling is called aging. The aging treatment with lower aging temperature or shorter holding time is called incomplete artificial aging; The aging treatment with higher aging temperature or longer holding time is called complete artificial aging. Incomplete artificial aging can make the casting obtain excellent comprehensive mechanical properties, that is, high strength, good plasticity and toughness, but the corrosion resistance may be low. Full artificial aging can make the casting obtain the maximum strength, that is, the highest tensile strength, but the elongation is low.
4. recycling. The process of cooling the casting to sub-zero temperature for many times, keeping the temperature for a certain time and then heating it to the working temperature of the casting is called cyclic treatment. Cycling treatment can improve the dimensional stability of castings and is suitable for the treatment of precision parts.
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