With the increase of industrial products, the spring products are now enriched, the amount of Wave Spring is gradually increasing, and the spring-related technology is slowly maturing. How to increase the spring life is a problem that most spring manufacturers need to face.
(1) deformation heat treatment
The deformation heat treatment generally combines both the deformation strengthening and the heat treatment strengthening of the steel to further improve the strength and toughness of the steel. The deformation heat treatment has high temperature, medium temperature and low temperature. The high temperature deformation heat treatment is generally quenched immediately after deformation in a stable austenite state, and can also be combined with forging and hot rolling, that is, quenching immediately after thermoforming.
(2) Austempering of springs
For springs with small diameters or sufficient hardenability, austempering can generally be used, which not only reduces the variation of the core, but also improves the toughness. After the austempering, it is better to temper again, so that the elastic limit can be increased, and the tempering temperature and the austempering temperature are the same.
(3) Shot peening
Shot peening is one of the most widely used methods for improving the surface quality of springs. Springs require a high surface quality. Surface defects such as scratches, folds, oxidative decarburization tend to be places where stress is concentrated during spring operation and sources of fatigue fracture. If the surface of the spring is sprayed at a high speed with a small steel shot, the shot peening treatment not only improves the surface quality of the spring, but also improves the surface strength, so that the surface is in a state of compressive stress, thereby improving the fatigue strength and service life of the spring.
(4) Relaxation treatment of the spring
The spring works under the action of external force for a long time. If the stress is relaxed, a slight permanent (plastic) deformation will occur, especially the spring working at high temperature, the stress relaxation phenomenon is more serious at high temperature, and the precision of the spring is lowered. Precision springs are not allowed. Therefore, such springs should be relaxed after quenching and tempering.
(5) Low temperature carbonitriding
For the coil spring, the combination of tempering and low-temperature carbonitriding (soft nitriding) can significantly improve the fatigue life and corrosion resistance of the spring.