Auto Leaf Spring Shot Peening Treatment Research

With the now with the development of modern transportation industry, the performance of the spring steel requirements more and more high, there is an urgent need to improve the strength of the steel spring and prolong the service life, and shot peening is to improve the fatigue life of mechanical parts of a commonly used surface treatment process, is widely used in automobile, aircraft and other manufacturing industries.This paper mainly to small pieces of variable cross-section leaf spring and sample as the object of study, through experiments to study plate spring shot peening process, heat treatment process and microstructure of workpiece and physical parameters change between the relationship, to find out the effect of strengthening shot peening effect of main factors and law. On the one hand to formulate reasonable shot peening process and heat treatment process to find the theoretical basis, on the other hand, according to the change of various microstructural and physical parameters to determine production and the effect of shot peening, for improving the production quality and product design to provide theoretical basis.Shot peening is using high-speed projectile flow hit the surface of the metal member, produce the plastic deformation layer and the introduction of compressive residual stress on the component surface and to improve parts of the fatigue performance and change the parts of the state of the surface. Spring plate after preliminary heat treatment surface conditions will change, mainly reflected in different surface tempering hardness, surface decarburization layer depth, surface oxide thickness is different. All of these will affect the steel spring late shot peening effect, also shot medium that shot peening pellets diameter, hardness, shot peening velocity different, have certain effect on Spray after spring surface roughness, peening coverage, residual pressure force field depth etc. factors. The residual compressive stress layer formed on the surface of the steel plate spring can effectively prevent the initiation and propagation of the crack source, and greatly prolong the fatigue life of the steel plate spring.In this paper, with the following three kinds of materials: 60Si2Mn(M), 50CrVA(V), FAS3550(F) to study and analysis of leaf spring shot peening. According to the experimental data show that the three kinds of materials after shot peening treatment of the surface of the leaf spring and time are formed on the surface of the residual compressive stress layer, shot peening treatment after treatment of leaf spring fatigue crack initiation of cyclic time is much higher than before the shot peening of leaf spring, which improved after the injection of leaf spring fatigue life had big enhancement.Through the experimental study on a round of, constantly adjust shot peening, gradually in order to adjust is introduced into the residual compression stress field of four characteristics, to meet optimum residual compressive stress field of two criterion in order to obtain the optimized peening residual stress field. At this time, the four parameters of the residual stress field, coupled with the micro hardness, coverage, and a half high wide index, can be used as a quantitative indicator of the effect of shot peening.Final leaf springs in order to reduce the reed contact fatigue and the fatigue life is increased, leaf spring in post production take shot peening strengthening treatment, the surface of the reed obtained good compressive residual stress field, high peening coverage and small roughness, so that the steel plate spring for high fatigue.