What is Induction Hardening?

Induction hardening is one of the type of the surface hardening processes. In this hardening process, the metal part is passed through induction heating and then through quenching. After quenching, the heated metal is converted into martensite. So, the metal in the martensite form has higher hardness and at the same time it increases the brittleness of the material.

History Behind the Induction Hardening:

The Michael Faraday is the person behind the induction hardening. Faraday discovered the phenomenon of the electromagnetic induction in 1831. Later the engineers at the Midvale steel and The Ohio Crankshaft Company use the Faraday’s electromagnetic induction and induction heating for the first time.

Induction heating is the heating process which is operated on the principle of the electromagnetic induction. In induction hardening, the metal is heated with the help of changing magnetic fields above or below its critical temperature and then passed through the quenching process. It is mostly suitable for steel alloys which contain 0.4% of carbon. In this technique, the eddy currents are produced on the surface of the metal. These eddy current increases as a result of weak resistance which gives rise to Joule’s heating. And we get the required heat in the form as I2R. Here, I is the current and R is the resistance.

In induction hardening there are a number of methods that you must know:

Traverse Hardening:

Traverse hardening is used in the manufacturing of equipment like drive shafts, steering components and shafts. In transverse hardening, the given metal is passed through the induction coil steadily. Transverse hardening also finds its applications in the production of the blades like hacksaw blades and bottom blades and also in the manufacturing of knives made up from paper or leather.

Also Read:

What is Quenching Process And Why it is Necessary?

What is Cryogenic Treatment?

What is Annealing Process and Why it is done?

Single Shot Hardening:

In the single shot hardening, the metal is kept in the static position and it is heated uniformly from all the sides. In single shot hardening a coil is used. There are a lot of disadvantages of the single shot hardening:

  1. The coil which is used in the single shot hardening has a very complex design.
  2. To practice single shot hardening, a lot of power supply is required.

Role of power supply in the induction heating:

Induction heating requires power supply ranging from few kilowatts to hundreds of kilowatts. For determining the amount of the power supply required in the induction heating it is essential to first calculate the surface area of the metal.


  • It is a super-fast process and requires a very less time to take place.
  • It helps in increasing the wear resistance of the metal
  • It also results in improving the hardness of the metal.


  • With the help of induction heating, equipment like axle can be manufactured easily as well as effectively.
  • Induction hardening is used in the processes related with steel.

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