Development Of Hard And Tough Steel Shot

Author:  Hatano, Namiki, Endo, Doizaki
Source:  Conf Proc: ICSP-4, (p. 37-46)
Doc ID:  1990019
Year of Publication:  1990
Abstract:  
In order to enhance the performance of machines, steel components have been shot peened, recently very hard with the arc height more than 0.7mmA. Such a process requires hard shot media around HV700, especially for peening on case hardened components. Generally the harder media become more brittle and so shorter lives. The authors have succeeded in developing hard and besides tough cast steel shot produced by centrifugal atomizing. The reduction of C content revealed the most effective to improve the toughness of particles. Therefore, the newly developed steel shot contains 0.5%C, instead of 0.8%C in conventional one, and also 0.5%Si and 0.3%Mn. The hardness of the new grade shot remains HV700 and the life of it extends to four times of conventional one's. The peening effect of the new grade proved to be the same as conventional one's for the gears in JIS SCM420 (SAE4118) carburized and shot peened with the arc height 1.0mmA, that is, the residual compressive stress and fatigue strength are analogous to those of gears peened by conventional steel shot. Descriptors: Shot peening, Hard shot peening, Fatigue strength, Toughness, Cast steel shot, Centrifugal atomizing, Residual stress