Heat Treatment process generally includes heating, holding, cooling three processes, these processes are interlocked and can not be interrupted. Heat treatment is the metal material in a controlled atmosphere or protective atmosphere, molten salt and vacuum heating to above the phase change temperature to obtain high-temperature tissue, insulation for a certain period of time, so that the internal and external temperatures are consistent, so that the microstructure transformation is complete, with a certain rate of cooling to room temperature or lower, so as to improve the structure of the material, to obtain excellent performance of the material.