There are many different types of hardening treatments that can be used for various metals and alloys. One process that can be used to create a martensitic transformation in a metal is induction hardening.
An Introduction to The Process
The key factor with induction hardening is the use of induction heating. In other words, the surface of the metal is not in contact with a heat source to cause the rise in temperature. Instead, electromagnetic induction is used to heat the material from the inside out at the surface layer.
This is done by exposing the conductive metal to a magnetic field. As this magnetic field alternates, the electromagnetic energy flows into the metal, just under the surface layer. The depth to which the electromagnetic energy will penetrate is a factor of the metal as well as the magnetic field strength.
As the surface layer heats it is quenched, typically in water or oil, but sometimes in a specific type of polymer based material. This rapid cooling process alters the surface layer to make it much harder than the inner core of the metal.
The Advantages
In addition to a much harder and more durable surface layer, the use of induction hardening also prevents changes to the inner core of the base metal. This would not be possible with contact heating where the outer surface and inner core would heat at the same time.
By going through this hardening treatment, parts and components will have a much longer life cycle. They will also be more resistant to wear and tear in operation, extending the life and also reducing part or component failure.
This is a hardening treatment that is used in the automotive industry and also by OEMs manufacturing equipment for production. It is a low cost, highly effective option for any type of conductive and magnetic metals.