site logo

Defects in heat treatment of induction heating equipment

Defects in heat treatment of induction heating equipment

Some common defects and countermeasures to be taken in the heat treatment of the use of intermediate frequency induction heating equipment,

1) Insufficient hardness


1. The unit surface power is low, the heating time is short, and the gap between the heating surface and the inductor is too large, which reduces the induction heating temperature, and there is more undissolved ferrite in the quenched structure

2. The time interval from the end of heating to the beginning of cooling is too long, the spraying time is short, the spraying liquid supply is insufficient or the spraying pressure is low, the quenching medium cooling speed is slow, so that non-martensitic structures such as troostite appear in the structure.

The countermeasures taken are:

1. Increase the specific power, extend the heating time, and reduce the distance between the inductor and the surface of the workpiece

2. Increase the supply of spray liquid, reduce the time from the end of heating to the beginning of cooling, and increase the cooling rate.

Soft spot

Cause: The spray hole is blocked or the spray hole is too thin, which reduces the cooling rate of the local area of ​​the surface.

Countermeasure: Check the spray hole

Soft belt

Cause: When the shaft workpiece is continuously heated and quenched, a black and white spiral band appears on the surface or a linear black band appears in a certain area along the movement direction of the workpiece. There are non-martensitic structures such as undissolved ferrite and troostite in the black area.


1. Small spray angle, backwater in heating zone

2. The rotation speed of the workpiece is inconsistent with the moving speed, and the relative movement distance of the sensor is relatively large when the workpiece rotates once.

3. The angle of the spray hole is inconsistent, and the workpiece rotates eccentrically in the sensor


1. Increase the spray angle

2. Coordinate the rotation speed of the workpiece and the moving speed of the sensor

3. Ensure that the workpiece rotates concentrically in the induction furnace of the intermediate frequency diathermy furnace