Bearing steel ball in the production process of its pre-heating quenching before heating, its attention to its purpose in Austria is to shorten the quenching heating time, so that it can effectively reduce the deformation cracking, but also can be reduce the tendency of overheating and decarburization, the process using salt bath furnace preheating, the temperature is about 600 ℃, preheating 8-10 minutes, if using a box-type electric furnace preheating, the temperature is about 530-550 ℃ longer .
Bearing steel ball to determine the heating time, during the operation of the plant to determine the heating time is not the same, under normal circumstances will be effective after the preheating of the heating time is 10-15s / mm, box Electric furnace 35-50s / mm. Without preheating salt stove 30-35s / mm, box-type electric furnace 90-100s / mm. In this case GCr15 bearing ball after preheating salt furnace quenching heating time to consider loading furnace take 8 minutes.
Bearing steel ball quenching, GCr15 bearing balls contain more alloying elements, hinder the composition of the homogenization, but also to prevent GCr15 bearing steel deformation and also have some toughness and fatigue resistance, so the oil cold.
Improvement Measures of High Carbon Martensitic Bearing Ball to Prevent Cracking Process
Forging Increase the forging ratio, forging process control strictly to prevent the forged heart organization coarse.
2. To reduce the bearing steel ball quenching water temperature, increase the water temperature, the workpiece quenching stress can be significantly reduced and mitigated.
3 before quenching increase spheroidizing annealing, refine the organization, so that after the workpiece was fine needle-like (fine tablets.) Martensite, to prevent the formation of coarse tissue after quenching.
4. Tempering after quenching in time to eliminate quenching stress, stable organization, to further remove the risk of cracking of the workpiece.