In the process of plate flange heat treatment, annealing cooling speed is the slowest, normalizing cooling speed is faster and quenching cooling speed is faster. However, there are different requirements because of different kinds of steel. For example, air-hardened steel can be hardened at the same cooling rate as normalizing. These processes of plate flange are connected with each other and can not be interrupted.
When metal is heated, the plate flange is often oxidized when the workpiece is exposed to air. Decarbonization, which has a negative impact on the surface properties of parts after heat treatment. Plate flange metals should normally be controlled or protected in an atmosphere. Molten salt neutralization and vacuum heating can also be used by coating or packaging methods for protective heating.
In addition, the heating temperature of flange is one of the important technological parameters of heat treatment process. Selecting and controlling the heating temperature is the main problem to ensure the quality of heat treatment. The heating temperature varies with the treated metal materials and the heat treatment items, but generally it is heated to the phase transformation temperature above to obtain the high temperature structure. Heating is one of the important processes of heat treatment. There are many heating methods for plate flange metal heat treatment, the earliest one is to use charcoal and coal as heat sources, and then use liquid and gas fuels. Nowadays, many manufacturers use electric applications, which are easy to control and free of environmental pollution. These heat sources can be directly heated or indirectly heated by molten salts or metal or floating particles. At the same time, the performance of flanged pipes varies with different cooling methods, and the cooling speed is mainly controlled.
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