Today, China branded a small compilation to introduce you to the introductionHeat Treatment Spring steel BeltProcess skills.
Spring steel requires high strength and fatigue limits, generally in quenching+ Medium temperature Tempering in the state of use, in order to obtain a higher elastic limit. Heat treatment technology has a crucial effect on the inner quality of the spring. Therefore, how to further improve the fatigue life of spring, it is necessary to further study, especially chemical surface modification heat treatment, shot peening and so on have an important impact on spring fatigue life. In order to further strengthen the surface strength of valve spring, increase compressive stress, improve fatigue life, after valve spring forming, it is necessary to further through nitriding, low-temperature liquid carbon-nitrogen co-seepage or sulfur-nitrogen co-seepage treatment, and then reinforced by shot peening. For example, in Japan, the fatigue limit of f4mm's SI-CR oil quenching steel wire can be increased by 240mpa by 450℃x4.5h low temperature carbon and nitrogen co-seepage with 400℃x15min medium temperature tempering. Nitrogen infiltration not only eliminates the adverse effects of decarbonization, but also improves the residual compressive stress, while increasing the high temperature strength of the valve spring through nitriding and cryogenic liquid carbon-nitrogen co-seepage, the deformation at 150 ℃ is 0.2% (the specified value is 0.5%), and the deformation of 250 ℃ is 0.56%, The thermal stability and anti-relaxation stability of valve spring are improved, but the time of nitriding and liquid carbon and nitrogen co-seepage should be strictly controlled, otherwise reticulated sulfide and mesh nitride will be formed, but the fatigue strength will be reduced.
Valve spring to improve the strength of the method can also choose shot peening, through the production of practice surface valve spring shot can be used two kinds of pellets, a diameter of0.8mm, its microhardness is 720hv0.2, another diameter of 0.25mm, its microhardness is 800hv0.2, three shot peening can achieve a better strengthening effect, but also can improve the surface quality.
The above isHeat Treatment Spring steel BeltProcess skills.