For the heat treatment of GCr15 bearing steel balls, the key is to master the preheating, heating time and cooling of the process to obtain the desired effect. GCr15 bearing steel ball preheating before quenching, its main purpose is to shorten the quenching heating time and reduce deformation cracking.
At the same time, it can also reduce the tendency of GCr15 bearing steel ball to overheat and decarburize. The process adopts preheating in salt bath furnace. The temperature is about 600 °C, preheating for 8-10 minutes. If box type electric furnace is used for preheating, the temperature is 530-550. °C is longer.
Secondly, the heating time of the GCr15 bearing steel balls is not exactly the same in each factory. Generally, the heating time after preheating is 10-15s/mm, and the box type electric furnace is 35-50s/mm; the preheating salt furnace is 30-35s/mm, box-type electric furnace is 90-100s/mm. For the GCr15 bearing steel ball, it is usually taken after the preheating to take the furnace amount for 8 minutes in the salt furnace quenching heating time.
Since the GCr15 bearing steel ball contains more alloying elements, it will hinder the homogenization of the components, and also to prevent the deformation of the GCr15 bearing steel ball and also have certain toughness and fatigue resistance, so the cooling effect with oil is the best.