Induction hardening is a selective heat treatment that uses electromagnetic induction to generate heat inside the surface layer of a metal part. The quenched metal undergoes a martensitic transformation, increasing the hardness and brittleness of the part. Induction hardening is used to selectively harden areas of a part or assembly without affecting the properties of the part as a whole. This process is commonly used to increase the hardness and wear resistance of various metal components. Like any industrial process, induction hardening has its advantages and disadvantages.
Advantages of induction hardening
- It can heat and cool a metal component much faster than other methods, such as flame or furnace hardening.
- It can customize the hardness of the steel workpiece to the desired level.
- It can produce hard, highly wear-resistant surfaces (deep case depths) with good capacity for contact load and good bending fatigue strength.
- It can repair warranty claims or field failures without having to redesign the component.
- It can use low-cost steels such as 1045.
Disadvantages of induction hardening
- It requires an induction coil and tooling that relates to the part’s geometry. Since the part-to-coil coupling distance is limited, it may be difficult to heat thicker or irregularly shaped parts evenly.
- It has a greater likelihood of cracking compared to most heat treatment processes. This is due to the rapid heating and cooling process that can cause thermal stresses and distortions in the metal.
- It can produce hard, brittle surfaces that are prone to cracking under impact or fatigue loading. The hardness of the surface layer may not match the hardness of the core or other parts of the component.
- It can cause intergranular cracking due to the thermal expansion that concentrates impurities at grain boundaries. This can weaken the grain structure and reduce the ductility of the metal.
- It can retard recovery processes and leave more defects, such as dislocations and vacancies, in the material. This can affect the mechanical properties and performance of the metal.