Defects and preventive measures caused by ultrasonic induction heating equipment when heat treating hobs and saw blade milling cutters

Hobs and saw blade milling cutters are made of high-speed tool steel, which requires high hardness and good red hardness. Many manufacturers use ultrasonic induction heating equipment for simple heat treatment of hobs and saw blades. During the heat treatment process (quenching, tempering and cooling) of hobs and saw blade milling cutters, some simple heat treatment defects will occur due to the influence of raw materials, human factors and environmental factors. Zhengzhou Gou's has been engaged in induction heating equipment for many years and has many methods on how to prevent these defects. Today, we will share it with you.

1. Overheating or overburning will cause the workpiece to deform greatly, reduce its toughness, and reduce the service life of the workpiece. The cause is that the quenching temperature is too high or the heating time is long, or the cutting tool or the card in contact with it has rust. We can lower the quenching temperature and shorten the heating time.

2. Uneven hardness will reduce the service life of the workpiece. Causes and defensive measures:

(1) Heating causes local decarburization of forgings, and we should strictly implement deoxidation treatment.

(2) When quenching, too much is loaded into the furnace at one time, or the holding time is too short. We should strictly implement the heat treatment process and inspect the grains.

3. Insufficient hardness. Insufficient hardness is a common defect in the heat treatment of workpieces. The occurrence of this defect will reduce the wear resistance and service life of the workpiece. The causes and preventive measures are as follows:

(1) If the quenching temperature is too low or the holding time is short, we should strictly implement the quenching process parameters to avoid the temperature or holding time not meeting the requirements.

(2) Multiple heatings cause severe decarburization of the surface of forgings. If re-quenching is required, annealing should be carried out in a salt bath furnace or protective atmosphere furnace with sufficient deoxidation.

(3) The preheating temperature is too low. We strictly control the preheating temperature.

(4) The tempering temperature is too high. For this reason, we should check and calibrate the set tempering temperature. We also need to check the instrument to avoid losing control of the instrument.

(5) If the chemical composition of steel is unqualified, we should strictly check the raw materials and prohibit the use of steel with unqualified composition.

4. If the hardness is too high, the workpiece will be more brittle and prone to chipping. Causes and defensive measures:

(1) The quenching temperature is high and the quenching temperature must be strictly controlled.

(2) The carbon content of the steel is too high, so steel with composite requirements should be used.

(3) The high-temperature tempering is insufficient or the time is short. We should check whether the tempering is sufficient.

5. Strip fracture has low strength and toughness, and the workpiece is easy to chip and break during use. Causes and measures:

(1) The annealing after forging is insufficient, the workpiece should be fully annealed.

(2) There is no annealing treatment between the two quenching processes, and sufficient annealing treatment is performed between the two quenching processes.

(3) The forging stop temperature is too high and the deformation is too small during forging. We should strictly control the forging stop temperature and the deformation should meet the minimum requirements.

6. Cracking or chipping of teeth will render the workpiece unusable. Causes and preventive measures for this defect:

1. If the hardness is too high after tempering, we need to increase the tempering temperature or lower the quenching temperature.

2. Insufficient tempering. We need to perform high-temperature tempering three times and perform metallographic inspection after tempering.

3. The raw materials have large carbide segregation or uneven structural composition. We must choose qualified raw materials.

Zhengzhou Gou's is a manufacturer specializing in the production of ultrasonic induction heating equipment. Its products have a wide range of applications. They can not only be used to quench workpieces, but also weld workpieces. If you want more detailed information, please call us.