Surface quenching is a local quenching method that hardens the surface of a steel component to a certain depth while keeping the core in an un quenched state. The most widely used methods in production currently are induction heating surface quenching and flame heating surface quenching.
Induction heating surface quenching is the process of placing a steel component in an induction coil. When a certain frequency of alternating current is applied, an alternating magnetic field of the same frequency is generated around the induction coil. The steel component in the magnetic field will generate a closed induction current of the same frequency and opposite direction as the induction coil. By relying on the thermal effect of induced current, steel parts can be quickly heated to quenching temperature within a few seconds, and then immediately cooled to achieve surface quenching.
Flame heating surface quenching is a quenching process that uses oxygen acetylene or other combustible gas flames to heat the surface of steel parts and then rapidly cool them.