Heat treatment strengthening technology of spring
1) Protective atmosphere heat treatment.In China, protective atmosphere heat treatment is used in the heat treatment of spring, oil quenching and tempering steel and toughened steel with wire less than 15mm.Protective atmosphere heat treatment can eliminate surface decarburization and oxidation and improve the surface quality of materials.
2) Induction heating or protective atmosphere induction heating heat treatment.This process is usually carried out on the wire before the coil spring is formed. Some spring factories combine the heat treatment of the wire material with the spring making to reduce the cost.Induction heating treatment has a good strengthening effect. Induction heating has a fast speed, which helps to refine grain and reduce surface decarburization. It can give full play to and improve the strength and toughness of materials.
3) Surface nitriding heat treatment technology.In recent years, high stress valve spring or other high stress clutch spring in order to achieve a reliable fatigue life, also use surface nitriding technology, now more advanced technology is low-temperature gas nitriding technology, the general nitriding temperature is (450 ~ 470) ℃, gas nitriding time is (5 ~ 20) h.
(2) Shot peening technology of spring
1) Combined shot peening technology.Combined shot peening, also known as multiple shot peening process.Most economical processes are secondary shot peening.By using different diameters of shot peening to achieve.*** larger pellets are used to obtain residual compressive stress and surface finish.
2) Stress shot peening process.The stress shot peening process is also a classic shot peening process, which is difficult to be used in mass production. However, due to the rapid development of stress shot peening equipment in recent years, it has been greatly developed in the mass production of high-stress automobile suspension springs.In particular, the combined application of stress - enhanced shot peening and other shot peening processes has a good strengthening effect.The prestress of stress shot blasting is generally set at (700 ~ 800) MPa. After stress shot blasting, the peak value of residual stress can reach (1200 ~ 1500) MPa, thus obtaining a high fatigue strength.
(3) Thermal compression technology of spring Thermal compression technology is mainly used in the spiral spring with high resistance to deformation, as the anti-deformation stabilization technology .The thermal compression process can not only significantly improve the deformation resistance, but also improve the fatigue life.
