Technology to improve spring quality

Isothermal quenching of the spring - for small diameter or enough permeability of the spring can be used isothermal quenching, it can not only reduce deformation, but also improve the strength and toughness, the best tempering after isothermal quenching, can improve the elastic limit, tempering temperature and isothermal quenching temperature the same.

Deformation heat treatment - the combination of steel deformation strengthening and heat treatment strengthening to further improve the strength and toughness of steel. Deformation heat treatment has high, medium and low temperature points. High temperature deformation heat treatment is quenched immediately after deformation in the stable austenite state, and can also be combined with forging or hot rolling, that is, quenched immediately after hot forming. Deformation heat treatment has been applied in the production of automobile plate springs.

Spring relaxation treatment - spring for a long time under the action of external force, due to the stress relaxation results will produce a trace of permanent (plastic) deformation, especially the high temperature working spring, at high temperature stress relaxation phenomenon is more serious, so that the precision of the spring is not allowed for general precision spring. Therefore, this kind of spring should be relaxed after quenching and tempering - the spring is pre-loaded, so that its deformation exceeds the amount of deformation that may occur when the spring is working. Then it is heated at a temperature of 20C above the working temperature and kept for 8-24h.

Low temperature carbonitriding - The combination of tempering and low temperature carbonitriding (soft nitriding) can significantly improve the fatigue life and corrosion resistance of the spring, and this process is mostly used for coiling springs.

Surface defects such as scratches, folding, oxidation and decarburization often become stress concentration places and fatigue fracture sources when the spring is working. If the spring surface is sprayed with small steel balls at high speed, it can not only improve the surface quality of the spring, improve the surface strength, but also make the surface in a state of compressive stress, thus improving the fatigue strength and service life of the spring.