How can we prevent defects caused by heat treatment of speed-regulating springs with ultrasonic induction heating equipment?

Speed regulating springs are widely used in machinery such as diesel engines. They are subjected to repeated effects of high pressure and high frequency during work. Therefore, they are required to have high hardness. Therefore, we commonly use ultrasonic induction quenching equipment to perform heat treatment such as quenching and tempering on the speed regulating spring. However, during the heat treatment process, some defects will inevitably occur. Today, we will focus on understanding the causes of defects and how to prevent them?

1. Decarbonization. Decarburization is mainly caused by high heating temperature or long heating time. Therefore, we should control the heating temperature and heating time.

2. Reasons for unqualified deformation and preventive measures:

(1) The tempering temperature is low or insufficient, and the hardness is too high. We should fully temper the workpiece, and the temperature should comply with the process specifications.

(2) Improper heat treatment operation, care should be taken during operation to avoid collision with foreign objects during quenching.

(3) High heating temperature results in coarse tissue. We should strictly control the heating temperature. The holding time should be determined according to the diameter and the size of the furnace.

3. High hardness. The reasons for this defect and preventive measures:

(1) The temperature difference in the furnace is too large. We should ensure that the heating temperature in the furnace is uniform.

(2) If the medium temperature tempering temperature is low or the holding time is short, we should strictly implement the process operation and strengthen the hardness inspection.

4. Causes and preventive measures of overheating: 

(1) Raw materials have coarse crystals. We should strictly inspect the raw materials to ensure that they meet the requirements.

(2) If the heating temperature is too high or the holding time is too long, we should strictly control the quenching heating temperature or forming heating temperature.

5. Causes and preventive measures for elastic deformation and misfitting of the rim:

(1) The hardness does not meet the regulations. We should control the hardness within the required range.

(2) Surface decarburization. During operation, perform according to process operations to avoid surface decarburization.

(3) It is not fully tempered within the required temperature. We should temper according to the required temperature and holding time.

6. Low hardness. Low hardness of the workpiece will reduce the service life of the workpiece. The reasons for low hardness and preventive measures are as follows:

(1) If the medium temperature tempering temperature is high or the holding time is short, we should strictly implement the process parameters to ensure that the tempering temperature and holding time meet the requirements.

(2) The heating temperature is low and not all austenitized. We should increase the quenching heating temperature appropriately.

(3) The cooling speed of the workpiece is slow and there is too much non-martensite. We should improve the cooling capacity of the quenching coolant to avoid the accumulation of springs. We should ensure that the required hardness is obtained after cooling and strengthen the metallographic inspection of the springs after quenching so that It meets the requirements.

Regarding the common defects of speed-regulating springs during quenching, tempering and other heat treatments using ultrasonic induction heating equipment, we will briefly introduce these today. If you want to know more detailed information, please call us.