How to improve the quality of the floor spring
1. Thermomechanical heat treatment--Combine the deformation strengthening and heat treatment strengthening of steel to further improve the strength and toughness of steel. Thermomechanical heat treatment is divided into high, medium and low temperature. High-temperature thermomechanical heat treatment is quenched immediately after deformation occurs in the stable austenite state, and can also be combined with forging or hot rolling, that is, quenched immediately after hot forming. Thermomechanical treatment has been used in the production of automobile leaf springs. (60Si2Mn)
2. Austempering of the spring-austempering can be used for springs with a small diameter or sufficient permeability. It can not only reduce deformation, but also improve strength and toughness. After austempering, tempering can be performed again to improve elasticity. , The tempering temperature is the same as the austempering temperature.
3. Spring relaxation treatment-the spring works under the action of external force for a long time, and the result of stress relaxation will produce a small amount of (plastic) deformation, especially the spring working at high temperature, the stress relaxation phenomenon is more serious at high temperature, making the spring The accuracy is reduced, which is not allowed for general precision springs. Therefore, this kind of spring should be relaxed after quenching and tempering-pre-load the spring so that its deformation exceeds the deformation that may occur when the spring is working. Then heat it at 20C higher than the working temperature for 8-24h.
4. Low-temperature carbonitriding-the process of combining tempering and low-temperature carbonitriding (soft nitriding) can significantly improve the fatigue life and corrosion resistance of the spring. This process is mostly used for coil springs.
5. Shot peening-surface defects such as scratches, folds, oxidative decarburization, etc. tend to become stress concentration places and sources of fatigue fracture during spring operation. If a small steel shot is used to spray the surface of the spring at high speed, it will not only improve the surface quality of the spring, increase the surface strength, and put the surface in a state of compressive stress, thereby increasing the fatigue strength and service life of the spring.