SURFACE HARDENING WITH INDUCTION
It is a surface hardening process performed by instantaneously heating and cooling the surface of the part with the help of induction current. It increases wear resistance, surface hardness and fatigue life by imparting a hardened layer to the outer surface without affecting the microstructure of the core. It is similar to flame hardening, but it is more efficient in terms of both processing time and high thermal accumulation on the surface. Flash cooling after induction heating is usually done with water and increases the likelihood of cracking in high carbon steels. Cooling water around 60 ˚C or using oil reduces the possibility of cracking and internal stress.Tempering (Blueing) is done between 150-200 ˚C to relieve internal stresses after hardening.
It is preferred in parts exposed to excessive load. Induction provides parts with a deep, hard surface on which they can withstand overloads. Fatigue strength is increased by the formation of a soft core surrounded by an extremely hard outer layer. These properties are required for surfaces subjected to torsional moment and impact. Commonly used parts for induction hardening include gears, shafts, axles, cam lobes, pressing assemblies, often symmetrical parts. Induction hardening is used to harden certain areas of parts. It is part-based and the desired parts of the part are hardened.
- Carbon steels
- Alloy steels
- Stainless steels (martensitic)
- Powder metallurgy parts
- Cast iron
- Gray cast iron
- Nodular cast iron
- Tempered cast iron