How to improve the service life of compression springs
1. Isothermal quenching: Isothermal quenching can be used for compression springs with small diameters or sufficient hardenability, which not only reduces the variation in the center, but also improves strength and toughness.
After isothermal quenching, it is best to perform another tempering, which increases the elastic limit, and the tempering temperature is the same as the isothermal quenching temperature.
2. Relaxation treatment: Compression springs work for a long time under the action of external forces, due to stress relaxation, a slight deformation will occur, especially in compression springs working at high temperatures.
The stress relaxation phenomenon is more serious at high temperatures, which reduces the accuracy of the compression spring, which will lead to the general precision compression shrinkage spring is not allowed.
Therefore, such compression springs should be relaxed after quenching and tempering.
3. Heat treatment process: Preload the compression spring so that it is deformed beyond the deformation that can occur when the compression spring is in operation. It is then heated at a temperature of 20°C above the working temperature and kept at that temperature for 8-24h.
4. deformation heat treatment: deformation heat treatment is a combination of deformation strengthening and heat treatment strengthening of steel to further improve the strength and toughness of steel. Deformation heat treatment can be divided into high temperature, medium temperature and low temperature.
High-temperature thermomechanical treatment is quenched immediately after deformation in a stable austenitic state, or can be combined with forging or hot rolling, that is, quenched immediately after hot forming.
Automotive leaf springs made of 60Si2Mn steel are subjected to high-temperature deformation heat treatment (930°C + 18% thermal deformation, oil quenching) and rapid tempering at 650°C. After 25 minutes, the strength and fatigue life are greatly improved.
5. Shot peening: Shot peening is one of the widely used methods to improve the surface quality of compression springs. Compression springs require high surface quality, and surface defects, such as scratches, folding, oxidation and decarburization
often become a source of stress concentration and fatigue fracture during compression spring operation. If you use high speed blasting and shot blasting on the surface of small compression springs not only improves the surface quality of the compression spring, but
It also improves the surface strength and puts the surface in a state of compressive stress, thus improving the fatigue strength and service life of the compression spring.