Dent and Affected Layer Produced by Shot Peening

Author:  K. Iida
Source:  The Shot Peener magazine, Vol 14 / Issue 3, Fall 2000
Doc ID:  2000033
Year of Publication:  2000
Abstract:  
Reprinted with permission from Proceedings of ICSP2 ABSTRACT This paper presents several basic factors for shot peening. Shot Peening consists of making of a dent, and the dent is formed by the impact of a steel ball. Laws of the dent formation as to the diameter and depth and volume for outside dent and inside dent which is yield zone of steel are obtained on the function of velocity and diameter of steel ball and hardness of material to be peened. Yield zone produced by shot peening makes affected layer which involves residual stress, change of hardness, and so on. The characteristics of formation of yield layer produced by shot peening are described. The hardness distribution in affected layer shows work hardening and work softening, then the distinction of both cases was cleared. Work softening phenomenon happens in cold workings of prestrained metals under certain combined strain. Residual stress in peened surface shows the size effect for thickness of specimen and decreases within the critical thickness related to peening conditions, and then, there is no residual stress in only affected layer made by etching from non-peened surface.