Can high-frequency quenching equipment quench steel with banded structure?

Induction hardening workpieces are generally made of medium carbon steel, and the problem of “band structure” is sometimes encountered in the quenching of medium carbon steel. The so-called banded structure is a defect of the original microstructure, and its ferrite is distributed in bands. During induction heating, banded ferrite is not easy to dissolve into austenite. Even with the best induction heating specification, residual banded ferrite can still be seen beside the field of view of martensite after quenching. After fire, the hardness is not uniform, and the effective hardened layer decreases, so that the mechanical properties of the workpiece (hardness, wear resistance, contact fatigue strength, etc.) decrease.

Banding can be improved by pre-normalizing, but it cannot be completely eliminated. In addition, it can also be improved by increasing the induction heating temperature of the workpiece, but this will lead to an increase in the hardness of the core of the workpiece and coarse martensite.