In the mechanical transmission system, the flange shaft plays an important role in transmitting torque and positioning, and its surface wear resistance directly affects the operating life and stability of the equipment. As the core means to improve the performance of metal materials, the heat treatment process can significantly improve its ability to resist wear by changing the organizational structure and mechanical properties of the flange shaft surface. From quenching and tempering to surface chemical heat treatment, multiple processes work together to ensure the reliable operation of the flange shaft under high load and high friction conditions.
Quenching and tempering is a basic heat treatment process to improve the surface wear resistance of the flange shaft. During the quenching process, the flange shaft is heated to above the critical temperature to transform the internal structure into austenite, and then quickly immersed in a quenching medium such as water and oil for rapid cooling, and the austenite is transformed into a martensite structure with extremely high hardness. This high-hardness martensite surface can effectively resist plastic deformation and material peeling during friction, and significantly improve wear resistance. However, the brittleness of the material after quenching is relatively large, and tempering treatment is required to eliminate internal stress and adjust toughness. Low-temperature tempering can reduce brittleness while maintaining high hardness, so that the flange shaft surface has good wear resistance and can withstand certain impact loads, balance the relationship between hardness and toughness, and meet the actual working conditions.
Carburizing treatment increases the surface carbon content by infiltrating carbon atoms into the surface of the flange shaft, thereby improving wear resistance. The flange shaft is placed in a carbon-containing carburizing medium (such as methane and propane in gas carburizing). Under high temperature conditions, carbon atoms gradually diffuse into the metal surface to form a carburized layer of a certain thickness. Subsequently, quenching and low-temperature tempering are performed to transform the carburized layer structure into high-hardness tempered martensite and carbide. Carbides are evenly distributed in the martensite matrix as hard particles, just like forming a "wear-resistant armor" on the surface, effectively hindering the cutting and plowing of the surface by abrasive particles, greatly improving the wear resistance of the flange shaft during friction contact, especially suitable for working conditions with heavy loads and strong friction.
Nitriding treatment is a heat treatment method that uses nitrogen atoms to infiltrate the surface of the flange shaft to form a hardened layer. In the nitriding furnace, the flange shaft reacts with ammonia or nitrogen-hydrogen mixed gas at a certain temperature, and nitrogen atoms diffuse into the metal surface to form nitrides such as iron nitride. The nitriding layer has extremely high hardness (up to HV 800-1200) and good thermal stability, and also has excellent anti-seizure and anti-corrosion properties. Compared with carburizing treatment, the nitriding layer is harder and less brittle, and can provide a solid wear-resistant barrier for the flange shaft surface without significantly reducing the toughness of the matrix. In addition, the nitriding treatment temperature is relatively low, which is not easy to cause flange shaft deformation, and is particularly suitable for improving the wear resistance of precision flange shafts with high precision requirements.
Induction heating surface quenching is used to quickly heat and cool the local parts of the flange shaft that are prone to wear to achieve surface strengthening. Through the principle of electromagnetic induction, an induced current is generated on the surface of the flange shaft, and the current thermal effect is used to quickly heat the temperature to the quenching temperature, and then the quenching is completed by spraying water cooling. This process has a fast heating speed and controllable heating layer depth, and can accurately strengthen key parts such as the journal and flange connection surface to avoid material performance changes and deformation problems caused by overall quenching. Since the hardened layer formed by induction heating surface quenching has a good transition with the matrix, while improving local wear resistance, it maintains good toughness of the matrix, so that the flange shaft can withstand local high friction and ensure overall structural strength.
To further improve wear resistance, multi-element co-diffusion and composite treatment technology are widely used. Multi-element co-diffusion simultaneously infiltrates two or more elements (such as carbonitriding and oxygen-nitrogen co-diffusion) into the surface of the flange shaft, combining the advantages of different elements to form a hardened layer with better comprehensive performance. For example, carbonitriding combines the high hardness of carburizing and the anti-seizure property of nitriding, so that the surface has both good wear resistance and fatigue resistance. Composite treatment is to combine multiple heat treatment processes or surface coating technology, such as carburizing and quenching first, and then hard chrome plating, to form a denser protective layer on the surface of the hardened layer, further reduce the surface roughness, reduce the friction coefficient, and enhance the wear resistance of the flange shaft surface from multiple dimensions to adapt to complex and harsh working environments.
The heat treatment process of flange shaft uses quenching and tempering, carburizing, nitriding, induction heating surface quenching and other methods to comprehensively improve its surface wear resistance from the perspectives of changing the material structure, increasing the surface hardness, and forming a special protective layer. Different processes have their own characteristics and applicable scenarios. In actual production, it is necessary to reasonably select or combine heat treatment processes according to the material, working conditions and performance requirements of the flange shaft. With the continuous development of materials science and heat treatment technology, more efficient and environmentally friendly heat treatment processes will be applied to flange shaft manufacturing in the future to continuously improve its wear resistance and service life, providing a solid guarantee for the stable operation of mechanical transmission systems.
