In the 1950s, induction heat treatment began to be applied in China. This new heat treatment process uses coil electromagnetic induction to heat the workpiece to quickly reach the quenching temperature, and then cool it rapidly, so that only the surface layer can obtain the quenched structure. It has the characteristics of fast heating speed, good working conditions, high surface strength and small deformation. Therefore, it is quickly accepted and developed by heat treatment workers.  
Advantages of induction heat treatment:
1. Energy saving in induction heating
The induction heating speed is fast, which can increase the phase transformation temperature of metal materials (50 ~ 100 ℃) and accelerate the austenite transformation process. After quenching, fine cryptocrystalline martensite is obtained on the surface, and the surface hardness is 2 ~ 3HRC higher than that of general quenching. Induction heating quenching and tempering treatment can save 35% ~ 50% electricity instead of box electric furnace quenching and tempering treatment; Induction heating can save electricity by 80% ~ 5% instead of surface hardening treatment such as carburizing and carbonitriding; Instead of overall heating and quenching in the furnace, power can be saved by 40% ~ 50%.  
2. Energy saving in tempering of induction heating parts
The induction heating is used to transfer the heat outside the quenching layer, and the quenching cooling does not take away all the residual heat to realize short-time tempering. It has high efficiency and energy saving. In many cases, such as high carbon steel and high carbon high alloy steel, quenching cracking can be avoided. At the same time, once the process parameters are determined, it has the advantages of mass production and remarkable economic benefits.  
3. Energy saving of induction heating equipment
The power consumption of induction heat treatment accounts for 20% ~ 25% of the total power consumption of heat treatment equipment. The thermal efficiency of electric furnaces commonly used in heat treatment in China is generally less than 55%, the quenching rate of box electric furnace is 30% ~ 40%, and the high temperature tempering rate is 40% ~ 50%. The carburizing rate of well gas carburizing furnace is 7% ~ 15%, the quenching and heating rate of medium temperature electrode bath furnace is 18% ~ 25%, and the tempering rate of well tempering furnace is 40% ~ 60%. The carburizing layer of 0.35 ~ 0.45mm can be obtained by high frequency induction heating DC discharge, and the surface carbon potential of the carburizing layer is 0.9% ~ 1.05%, which can greatly shorten the production cycle.  
At present, induction heat treatment can be used to replace quenching and tempering, normalizing, annealing and chemical heat treatment in general heat treatment for many workpieces. For example, carburizing quenching can be replaced by induction surface quenching of medium carbon steel, and quenching of some cutting tools, such as saw blade, file and other hardware tools; Induction quenching is adopted for plate spring, disc spring, cast iron guide rail, crankshaft and cam quenching, which has remarkable energy-saving effect, can shorten the production cycle and improve the economic benefit.  
Based on this, in production, we should further expand the application scope of induction heat treatment, publicize induction heat treatment, promote new equipment, new process and new technology of induction heat treatment, constantly improve the standards of induction heat treatment, incorporate them into the mechanical design manual, increase the proportion of induction heat treatment in production, and achieve great results in energy saving of heat treatment.