The quenching treatment of the outer surface of the rapidly heated part by solid phase modification is called external heat treatment, commonly known as external quenching. It contains flame quenching? High (medium) frequency induction hardening? Laser heating or electron beam heating quenching. The characteristics of these methods are: partial external heating and quenching, small deformation of the workpiece; fast heating speed, high production efficiency; short heating time, oxidative decarburization of the surface is very fine. This approach is particularly useful in improving the wear resistance and fatigue strength of large and very large bearing components that accept a certain impact load.
Chemical heat treatment strengthening
The method of modifying the chemical composition of the outer surface layer of the metal by the solid dispersion of the element to complete the surface strengthening is called chemical heat treatment strengthening, which is also called dispersion heat treatment. Alloying includes boronization, carburizing, carbonitriding, nitriding, nitriding, nitriding, sulphide, sulphide, sulphide, aluminized chrome alloying, Al-Si dispersion, etc. Various changes were made to the features. The compound is impregnated or dissolved in a matrix metal to constitute a solid solution, or combined with other metal elements to constitute a compound. In short, the soaking element can modify the chemical composition of the outer layer and can achieve different phase structures. The treatment process of the carburized bearing steel parts and the external nitriding strengthening treatment of the needle bearing sleeve are attributed to this strengthening method.
Surface metallurgical strengthening
The ability to re-melt and condense the metal of the outer skin of the workpiece to achieve the desired composition or texture is known as surface metallurgical strengthening. Including external auto-dissolved alloy or composite powder coating? Appearance of molten crystal or amorphous treatment? Appearance alloying. It is characterized by rapid heating of high energy density, melting of the outer surface of the metal or alloying material coated on the outer surface of the metal, and then solidification by self-cooling to obtain a strengthening layer having a special structure or a specific function. Depending on the process parameters and methods of surface metallurgy, the particular structure can be a refined crystal structure, or a supersaturated phase, a metastable phase, or even an amorphous structure.
The rolling bearing profession has discussed the research on the external laser heating of miniature bearings, and the effect is outstanding.
The outer membrane reinforcement is applied to physical or chemical methods, and the enhancement membrane layer coated on the metal appearance with different substrate properties is called outer membrane reinforcement. It includes electroplating, electroless plating (chrome plating, nickel plating, copper plating, silver plating, etc.) and composite plating, brush plating or conversion treatment, etc., including high-tech development such as CVD, PVD, P-CVD, vapor deposition film strengthening methods and ions. Injecting external reinforcement skills (also known as atomic metallurgy skills). A feature of their combination is that they can form a film with specific properties on the exterior of the work to enhance the wear resistance of the exterior. • Durability, corrosion resistance and self-lubricating properties. For example, the ion implantation technique enhances the bearing working surface and improves the wear resistance of the bearing working surface, corrosion resistance, and touch fatigue strength, which doubles the service life of the bearing.