This standard defines the key terms and definitions in metal heat treatment, covering the heat treatment process, organization and performance, and heat treatment equipment. Heat treatment is the process of adjusting the organizational structure and performance of metal materials through appropriate heating, insulation and chill down processes. According to the different treatment objects, it can be divided into overall heat treatment, local heat treatment and surface heat treatment. In addition, chemical heat treatment changes the chemical composition, organization and performance of materials by treating in an active medium. This standard applies to the formulation and application of relevant technical standards and documents.