X-ray Diffraction Study of Residual Macrostresses in Shot peened and Fatigued 4130 Steel

Author:  Esquivel, A.L. and Evans, K.R.
Source:  Experimental Mechanics Mag., Nov. 1968, p.496-503
Doc ID:  1968016
Year of Publication:  1968
Abstract:  
a study has been made of the effects of shot peening and fatigue cycling on the residual macrostresses determined by x-ray methods in an austenitized and tempered AISI 4130 steel. The results show that the effect of shot peening is to produce a residual compressive macrostress layer 0.014" deep. The residual stress profile exhibits a small negative stress gradient at and near the surface and a large positive stress gradient in the interior. Stress relaxation which occured early in the fatigue history of the specimen was found greater at the surface than in the subsurface layers. Stress gradients of the stress profile increased with continued cycling and varied with depth. A correlation appears to exist between stress relaxation and stress gradients at the surface.