Some parts in the workpiece in the alternating load, such as torsion and bending under impact load, the surface layer undertake higher stress than the core part. Occasions of friction, the surface layer is worn, some parts of the surface put forward the requirements on layer with high strength, high hardness, high wear resistance and high fatigue limit, only the surface enhanced to meet the above requirements. Hardening the surface deformation is small, the productivity advantages of the wide range of applications in production. Depending on the heating mode, the surface hardening, induction heating surface hardening, flame heating surface hardening, the electrical contact heating surface quench.
The basic principles of induction heating:
The workpiece on the sensor when the sensor by an alternating current, the same as the current frequency alternating magnetic field around the sensor, the induced electromotive force in the workpiece corresponding to the formation of the induced current in the surface, that is, vortex. Eddy current in the resistance of the workpiece under the action of electrical energy into heat, so that the surface temperature reaches the quenching temperature can be achieved surface quenching.
Induction heating performance after surface quenching
1, the surface quenching: The high, medium frequency induction heating surface quenching of the workpiece, its surface quenching is more often than the general quenching of 2 to 3 units (HRC).
2 workpiece wear resistance, abrasion resistance: high-frequency quenching after ordinary quenching. This is mainly the hardened layer of fine martensite grain carbide dispersion is high, and relatively high hardness, high compressive stress in the surface of the integrated results.
3, the fatigue strength: high, medium frequency surface quenching greatly improved fatigue strength, notch sensitivity decreased. The same material of the workpiece, the depth of hardened layer within a certain range, the increase in fatigue strength increases with the depth of hardened layer, but the depth of hardened layer is too deep when surface compressive stress, thus increase to fight the fatigue strength reduction rather than depth of hardened layer and the workpiece increased fragility. General hardening layer depth δ = (10 20)% D. More appropriate, where D The effective diameter of the workpiece.