Writer: Eric Bearing Limited
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 surface of the bearing material beautiful and smooth. ERIC BEARING LIMITED mainly shares the classification of surface hardening technologies for bearing steel materials, which are mainly divided into five technical classifications: chemical heat treatment, surface deformation strengthening, surface heat treatment, surface metallurgy strengthening and membrane surface strengthening.
1. Chemical heat treatment
Using solid phase diffusion to some elements to change the chemical composition of the metal surface layer, the method to achieve surface strengthening means strengthening 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 infiltration, graphitized layer, etc., varieties, characteristics. Infiltrate the element or dissolve into the base metal to form a solid solution, or form a compound with other metal elements. In the short chemical composition, the elements of the surface layer can be changed and different phase structures can be obtained. Carburized bearing steel reinforcement treatment process and Timken imported needle roller bearing sleeve surface reinforcement method nitriding.
2. Surface deformation strengthening
The metal surface layer is mechanically and plastically deformed to form a hardened layer with high hardness and high strength. The method of surface strengthening is called enhanced surface deformation, also called work hardening. Including shot peening, sandblasting, cold extrusion, rolling, rolling and impact, explosion impact, etc. The characteristics of these methods are: enhanced dislocation density increases, substructure refinement increases hardness and strength, and surface roughness decreases, which can significantly increase the surface fatigue strength of parts and reduce fatigue notch sensitivity. This kind of reinforcement method has the advantages of simple process, remarkable effect, hardened layer and matrix structure, no obvious boundary between coherence, and it is not easy to fall off and use. Many of the methods have been applied to the imported bearing industry: the application of surface impact to strengthen this rolling element, precision rolling into a new reinforcement method for ferrule processing.
3. Surface heat treatment
The use of solid-state phase change is quenched by parts, called surface heat treatment, and the surface layer is rapidly heated, 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: the surface is locally quenched, the deformation of the workpiece is small; the heating speed is fast, and the production efficiency is high; the heating time is short, and the surface oxidation and decarburization are very slight. This method is especially useful for improving the wear resistance and fatigue strength of large and extra-large imported bearing parts under obvious impact loads. SKF L555249/210 tapered roller bearings online , pls click here :
4. Surface metallurgy strengthening
Melting and solidification of the metal surface layer, in order to obtain the desired surface strengthening technology composition or structure surface metallurgical strengthening. Including surface self-dissolving alloy or composite powder coating, surface melting crystallization or amorphous treatment, surface alloying methods. Rapid heating with high energy density, metal surface layer or coating alloy material melting metal surface, followed by enhanced cooling and solidification, to obtain special structure or specific performance. This special structure or crystal structure refinement may also be the supersaturation stage, the metastable phase, or even the amorphous structure, according to different process parameters and surface metallurgy methods. In the miniature imported bearing imported bearing industry rolling work laser heating surface strengthening research, good results.
5. Film surface strengthening
Using physical or chemical methods, the performance of the metal surface coating on the substrate materials of different reinforcement layers is called enhanced surface film. It includes electroplating, electroless plating (chromium, nickel, copper, silver, etc.) and composite electroplating, brush plating or conversion process, including the rapid development of high technology in recent years: such as CVD, PVD, P-CVD and other vapor deposited films Strengthening methods and ion implantation surface strengthening technology (also known as atomic metallurgy 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 imported bearings can significantly improve the wear resistance, corrosion resistance and contact fatigue resistance of imported bearings, and double the life of imported bearings.