Influence of cartridge heater heating process
Anyone hopes that the cartridge heater produced can be used for a longer period of time, saving unnecessary expenses, and at the same time, it can be used in the process to improve the quality of the cartridge heater, and heat treatment is required to extend the life. What impact does the heating process have?
The deformation of the cartridge heater after heat treatment is generally considered to be caused by cooling, which is incorrect. cartridge heater, especially complex cartridge heater, the correctness of the processing technology often has a greater impact on the deformation of cartridge heater. It can be clearly seen from the comparison of some cartridge heater that the heating speed is relatively Faster and often produce larger deformations.
(1) Deformation reason: Any metal will expand when heated.Because steel is heated, the temperature of each part in the same cartridge heater (i.e. uneven heating) will inevitably cause each part of the cartridge heater. The inconsistency of the expansion results in internal stress due to uneven heating. At the temperature below the transformation point of steel, non-uniform heating mainly generates thermal stress, and if the heating is not uniform above the transformation temperature, it will also produce unequal time for structural transformation, which will generate structural stress. Therefore, the faster the heating speed, the larger the temperature difference between the surface of the single-headed electric heating tube and the core, the greater the stress, and the larger the deformation caused by the heat treatment of the single-headed electric heating tube.
(2) Precautions: When heating complex cartridge heater below the phase transition point, they should be slowly heated. Generally, the deformation of vacuum heat treatment of cartridge heater is much smaller than that of salt bath furnaces. ‚Use preheating. For low-alloy steel cartridge heater, one-time preheating (550-620ºC) can be used; for high-alloy steel cartridge heater, secondary preheating (550-620ºC and 800-850ºC) should be used.