Etude Par Diffractometrie X Et Par Microscopie Electronique Des Couches Grenaillees

Author:  Hakimi, Servant, Castex
Source:  Conf Proc: ICSP-2, (p.249-258)
Doc ID:  1984020
Year of Publication:  1984
Abstract:  
This paper reports the results of a study of shot-peened steel surfaces aimed at a better understanding of the mechanisms leading to the improvement invariably observed in the fatigue behaviour of shot-peened components. In an earlier study (Castex and Joubert, 1981), a theoretical model for the mechanical effects of shot-peening was developed and its validity verified on a number of types of steel. The current study is a follow-up on this earlier work with emphasis on residual stress measurements by X-ray diffraction and on transmission electron microscopy. The different steel specimens used were first heat treated to achieve several levels of hardness and then shot-peened at different Almen intensities. The results show that: (i) the surface strain during shot-peening may reach several percentage points; (ii) the level of the residual stresses reached is mostly characteristic of the material; (iii) there is in-depth residual stress accumulation ultimately leading to saturation; and finally (iv) the form and the density of the dislocations change rapidly with depth. Descriptors: Shot-peening; X-ray diffraction; Residual stresses; Electron microscopy