Is this an examination question? Or interview questions, general heat treatment normalizing, tempering, quenching, tempering and annealing. Generally, annealing is arranged after forging section to improve the internal crystal structure of forgings, which is beneficial to machining. It is also used to relieve welding stress after welding. Tempering is used to improve the mechanical properties of large workpieces, or for parts that require certain mechanical properties and are difficult to process after quenching. Tempering is used to reduce brittleness and eliminate or reduce residual stress. Arranging tempering after quenching also improves the crystal structure, improves the willfulness of quenched parts, and meets the use requirements. Tempering can stabilize the size of parts.

There are many kinds of annealing, such as stress relief annealing, spheroidizing annealing, complete annealing and isothermal annealing. Different processes have different structures and different mechanical properties. According to different materials and different mechanical requirements, the corresponding heat treatment is carried out.

Your question is very broad. If you are interested, you can buy a mechanical engineering material, which is published by the mechanical industry. Although it is not as detailed as the material specialty, it is enough for engineering application and can be regarded as understanding common sense.