Process Of Shot Peening And Cleaning And Preparing Shot Pellets Thereof

Author:  Straub, J. C.
Source:  US Patent 4,067,240
Doc ID:  1978005
Year of Publication:  1978
Abstract:  
A process of compression stressing shot pellets to increase the fatigue strength or resistance thereof to brittle fractures by impact of the pellets during shot peening and cleaning operations wherein the elastic radial tensile stress at the surface of the pellets is maintained at a safe low value during initial compression stressing and preparation for and performance of peening and cleaning operations. The process entails subjecting the pellets initially to compression stresses of sufficiently low value to avoid the spontaneous formation of superficial or surface cracks in pellets formed of notch sensitive material and then subjecting the pellets to stresses normal in shot peening and cleaning operations. The compression stresses occurring at the surface of the pellets in the initial step of the process minimize the likelihood of formation of surface cracks in the pellets when subsequently subjected to the greater impact forces to which the pellets are subject during peening and cleaning operations, thus increasing the life of the pellets.