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Why does high-frequency induction heating equipment produce process overheating?

July 30, 2021
The overheating phenomenon of high-frequency induction heating can generally be divided into general overheating, fracture inheritance and small structure inheritance.
The following is a simple analysis of the treatment measures for the three overheating phenomena:
1. General overheating phenomenon of high-frequency induction heating equipment: high-frequency induction heating If the temperature is too high or the holding time at low temperature is too long, it will cause the austenite grains to coarsen, which is called overheating. The fine austenite grains will cause the strength and toughness of the steel to decrease, the brittleness change temperature will decrease, and the deformation and cracking direction during quenching will increase. The cause of overheating is that the furnace temperature meter is out of control or mixing (usually caused by not knowing the process). 
2. The overheated structure can be annealed, normalized or repeatedly tempered at low temperature, and then re-austenized to refine the grains in a deformed environment. The hereditary phenomenon of high-frequency fracture of high-frequency induction heating equipment: steel with overheated structure, after reheating and quenching, although it can refine the austenite grains, occasionally still presents fine-grained fractures. There are many actual disputes about the occurrence of fracture inheritance. It is generally believed that impurities such as MnS have been dissolved into austenite and concentrated in the crystal interface due to excessive heating temperature, and these mixtures will precipitate along the crystal interface during cooling. It is easy to fracture along the fine austenite grain boundary when hit.
3. The genetic phenomenon of the small structure of high-frequency induction heating equipment: when steel parts with small martensite, bainite, and Widmanite structures are newly austenized, they are heated at a slow rate to the general high-frequency quenching temperature, and even then Lower, its austenite grains are still fine, this kind of sign is called structural heredity. To remove the heredity of small structures, central annealing or repeated low-temperature tempering treatment can be adopted.
 
The above phenomenon of overheating should be fully understood to avoid the loss caused by heating. If you need to know more technical issues, please consult our technicians.

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