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The overheating phenomenon in high-frequency induction heating can generally be divided into common overheating, fracturing inheritance, and fine microstructure inheritance.
Below is a brief analysis of the treatment measures for these three types of overheating phenomena:
If the temperature is too high or the low-temperature holding time is too long in high-frequency induction heating, the austenite grains will coarsen, which is referred to as overheating. Fine austenite grains can cause the strength and toughness of the steel to decrease, lower the temperature of brittle change, and increase the direction of deformation and cracking during quenching. The cause of overheating is usually due to the furnace temperature gauge being out of control or mix-ups (generally caused by not understanding the process).
Overheated microstructure can be treated by annealing, normalizing, or multiple low-temperature tempering, then re-austenitizing in a deformed environment to refine the grains. In high frequency induction heating equipment.
Steel with an overheated microstructure, after reheating and quenching, although it can refine austenite grains, occasionally shows fracturing of fine grains. There is considerable debate about the hereditary phenomenon of fracturing; it is generally believed to be due to excessively high heating temperatures, where impurities like MnS dissolve into the austenite and accumulate at the grain boundaries. When cooling, these mixtures precipitate along the grain boundaries, making it easy to fracture along the fine austenite grain boundaries when impacted.
Steel parts with fine martensite, bainite, and Widmanstätten microstructures, when re-austenitized at a slower rate to normal high-frequency quenching temperatures, or even lower, still have very fine austenite grains. This phenomenon is referred to as microstructure inheritance. To eliminate fine microstructure inheritance, central annealing or repeated low-temperature tempering can be used.
Understanding these overheating phenomena thoroughly is necessary to avoid losses due to heating. As a professional high frequency induction heating equipment factory, Junko provides customers with answers to technical questions.For more technical issues, please consult our technical personnel.
