What is the effect of annealing on the performance of deep groove ball bearings

In the manufacturing process of deep groove ball bearings, the initial state of the raw materials usually shows high hardness and high internal stress. For example, after forging and other processes, the internal grains of commonly used bearing steel are often coarse and accompanied by significant residual stress. At this time, spheroidizing annealing treatment is particularly important. This treatment spheroidizes the carbides in the steel by heating the bearing steel to above the austenitizing temperature and slowly cooling it, thereby forming a uniform and fine spherical pearlite structure. This process not only effectively reduces the hardness of the material, controlling it within the range of HRB88 to 94, but also eliminates the internal residual stress. This reduction in hardness significantly improves the cutting performance of the material, provides convenience for subsequent mechanical processing, improves processing efficiency and reduces tool wear. At the same time, the elimination of residual stress effectively prevents deformation and cracking of the bearing due to stress concentration during subsequent processing and use, thus laying a solid foundation for the dimensional accuracy and shape stability of the bearing.

As the manufacturing process advances, semi-finished bearings often experience work hardening after cold processing and other processes. In this case, recrystallization annealing becomes a key technology to solve this problem. Recrystallization annealing heats the semi-finished product to above the recrystallization temperature, transforming the deformed grains back into uniform equiaxed grains, thereby effectively eliminating work hardening and residual stress. This process is like an "energy restart" for the semi-finished bearing, restoring it to its original plasticity and toughness. The treated semi-finished product can better withstand deformation in subsequent cold rolling and other processing procedures, reduce the occurrence of processing defects, and improve the surface quality and dimensional accuracy of the bearing.

Annealing also plays a vital role in optimizing the organizational structure of deep groove ball bearings. A reasonable annealing process can make the internal organization of the bearing material more uniform and delicate, thereby improving the overall performance of the bearing. This uniform and delicate organizational structure helps to reduce the friction coefficient, increase the limiting speed, and enhance the ability to bear complex loads. For example, under the condition of large radial loads, annealed bearings can more effectively disperse stress, reduce wear, and thus extend service life. In addition, annealing also prepares the organization for subsequent heat treatment processes such as quenching and low-temperature tempering. The spheroidal pearlite structure formed after spheroidizing annealing provides favorable conditions for obtaining uniform and fine martensite structure during quenching, thereby significantly improving the hardness and wear resistance of the bearing.