When we understand the bearing manufacturing process, we usually find that the bearing will harden the surface of the material, which can strengthen the bearing surface and make the bearing material surface beautiful and smooth. The editor mainly shares the technical classification of surface hardening of bearing steel materials, which is mainly divided into five technical classifications: chemical heat treatment, surface deformation strengthening, surface heat treatment, surface metallurgical strengthening and film surface strengthening. 1. Chemical heat treatment The method of solid-phase diffusion into some elements to change the chemical composition of the metal surface layer to achieve surface strengthening represents enhanced chemical heat treatment, also known as thermal diffusion. Including boronizing, carburizing, carburizing and carbonitriding, nitriding and nitrocarburizing, sulfide and sulfur nitrocarburizing, chromizing, aluminum and silicon penetration, graphitized layer, etc., varieties, characteristics. Infiltrate elements or dissolve into the base metal to form a solid solution, or form compounds with other metal elements. In short chemical compositions, the elements in the surface layer can be changed, and different phase structures can be obtained. The reinforcement process of carburized bearing steel and the reinforcement method of nitriding on the surface of Timken imported needle roller bearing sleeves. 2. Surface deformation strengthening The metal surface layer is mechanically and plastically deformed to form a hardened layer with high hardness and strength. The method of surface strengthening is called enhanced surface deformation, also known as work hardening. Including shot blasting, sand blasting, cold extrusion, rolling, rolling and impact, explosion impact, etc. The characteristics of these methods are: increasing dislocation density, refining the substructure, increasing hardness and strength, and reducing surface roughness, which can significantly improve the surface fatigue strength of parts and reduce fatigue notch sensitivity. This reinforcement method has a simple process and significant effect. It has a hardened layer and a matrix structure. There is no obvious boundary between the continuity and it is not easy to fall off. Many methods have been used in the imported bearing industry: the application of surface impact to strengthen this rolling element method, and precision rolling has become a new reinforcement method for ring processing. 3. Surface heat treatment Using solid-state phase change, the surface layer is rapidly heated by quenching treatment of parts, which is called surface heat treatment, commonly known as surface hardening. Including flame quenching, high (medium) high frequency induction heating quenching, laser heating or electron beam heating quenching. The characteristics of these methods are: partial quenching of the surface, small deformation of the workpiece; fast heating speed, high production efficiency; short heating time, very slight surface oxidation and decarburization. This method is especially used to improve the wear resistance and fatigue strength of large and extra-large imported bearings under obvious impact loads. 4. Surface metallurgical strengthening The melting and solidification of the metal surface layer, in order to obtain the desired surface metallurgical strengthening of the composition or structure of the surface strengthening technology. Including surface autolyzing alloy or composite powder coating, surface melting crystallization or amorphous treatment, surface alloying methods. With rapid heating of high energy density, the metal surface layer or coating alloy material melts the metal surface, followed by enhanced cooling and solidification to obtain special structures or specific properties. This special structure or crystal structure refinement may also be a supersaturated phase, a metastable phase, or even an amorphous structure, depending on different process parameters and surface metallurgical methods. Research on laser heating surface strengthening of rolling work in the imported bearing industry of miniature imported bearings, good results. 5. Membrane surface strengthening Using physical or chemical methods, the properties of the metal surface coating on the substrate material of different reinforcement layers are called enhanced surface films. It includes electroplating, chemical plating (chromium, nickel, copper, silver, etc.) and composite electroplating, brush plating or conversion processes, including high technologies that have developed rapidly in recent years: such as CVD, PVD, P-CVD and other vapor deposition films Strengthening methods and ion implantation surface strengthening technology (also known as atomic metallurgical technology), etc. Their common feature is that the film can form specific properties on the working surface, improving the surface’s wear resistance, fatigue resistance, corrosion resistance and self-lubricating properties. For example, the surface strengthening technology of ion implantation of imported bearings can significantly improve the wear resistance, corrosion resistance and contact fatigue resistance of the imported bearing surface, doubling the service life of the imported bearings.

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