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The technological process of heat treatment
- Jun 24, 2018 -

Heat treatment process generally includes heating, heat preservation and cooling, sometimes only heating and cooling. These processes are interconnected and uninterruptible. Heating is one of the important processes of heat treatment. There are many heating methods for metal heat treatment, the first of which is to use charcoal and coal as heat source and to use liquid and gas fuel. The application of electricity makes heating easy to control and free from environmental pollution. These heat sources can be heated directly or indirectly by molten salt or gold, or even floating particles. Metal heating workpiece when it is exposed to the air, often occur oxidation and decarburization (that is, the surface carbon content lower) steel parts, the performance on the surface of the parts after heat treatment have a bad effect. Therefore, metals should be heated in a controlled atmosphere or a protective atmosphere, molten salt and vacuum, or by coating or packaging. Heating temperature is one of the important process parameters of heat treatment process. Selecting and controlling heating temperature is the main problem to ensure heat treatment quality. The heating temperature varies with the purpose of the treated metal materials and heat treatment, but it is usually heated above the phase change temperature to obtain the high temperature tissue. Another change will take time, so when the heating temperature of metal surface is achieved, still must in the temperature keeping time, make internal and external temperature, the microstructure change completely, this paragraph of time is called the heat preservation time. When high-energy density heating and surface heat treatment are adopted, the heating speed is extremely fast, generally there is no heat preservation time, and the heat preservation time of chemical heat treatment is usually longer.