There are significant differences in the state, structure, and performance requirements between the working surface and center of cylindrical roller bearing parts, and overall heat treatment often fails to balance them, and the potential of materials cannot be fully utilized. The application of material surface strengthening technology can not only effectively solve the differences in structure and requirements between the surface and the center, but also further enable the surface to obtain certain special working performance to meet the requirements of bearing working surface performance under specific conditions. This is very meaningful in the development of modern science and technology. The traditional surface strengthening method belongs to the category of heat treatment in terms of technology. The surface strengthening methods developed in modern times, such as laser, electron beam, ion beam, etc., not only apply some high-tech to the surface strengthening of materials, but also exceed the traditional heat treatment scope in terms of technology, forming new technological fields. Therefore, current surface strengthening technologies can form various classification methods from different perspectives, which can be roughly divided into five categories based on the physical and chemical processes of surface strengthening technologies: surface deformation strengthening, surface heat treatment strengthening, chemical heat treatment strengthening, surface metallurgical strengthening, and surface thin film strengthening.
By mechanical means, the metal surface layer undergoes plastic deformation, forming a high hardness and strength hardening layer. This surface strengthening method is called surface deformation strengthening, also known as work hardening. Including shot peening, sandblasting, cold extrusion, rolling, cold milling and impact, explosive impact strengthening, etc. The characteristics of these methods are: increasing the density of dislocation in the strengthening layer, refining the subgrain structure, thereby increasing its hardness and strength, reducing the surface roughness value, and significantly improving the surface fatigue strength of the parts and reducing the sensitivity of fatigue notches. This strengthening method has a simple process and significant effect. There is no obvious boundary between the hardened layer and the matrix, the structure is coherent, and it is not easy to fall off during use. Most of its methods have been applied in the bearing industry: surface impact strengthening of rolling elements is the application of such methods, and precision rolling has become a new method for ring processing and strengthening.
The use of solid-state phase transformation and rapid heating method to quench the surface layer of parts is called surface heat treatment, commonly known as surface quenching. This includes flame heating quenching, high (medium) frequency induction heating quenching, laser heating or electron beam heating quenching, etc. The characteristics of these methods are: local heating and quenching of the surface, small deformation of the workpiece; Fast heating speed and high production efficiency; The heating time is short, and the surface oxidation and decarburization are very slight.
