A New Concept For Fatigue Strength Evaluation Of Shot Peened Specimens

Author:  Jinkui, Mei, Renzhi
Source:  Conf Proc: ICSP-4, (p.255-262)
Doc ID:  1990001
Year of Publication:  1990
Abstract:  
In this paper, a new concept about the reason for improvement in fatigue property due to shot peening is suggested. It has been found that, for optimumly peened and/or peened and then ground specimens, fatigue failures nearly always start at some subsurface points where tensile residual stresses occur. Stress calculations show that the values of local fatigue strength at positions of fatigue source are about the same for these specimens, although their peening conditions are quite different. Then, it is reasonable to assume that, for a given material there should exist another kind of fatigue strength, namely, internal fatigue strength (IFS) which is different from fatigue strength in common sense (which should be called as surface fatigue strength (SFS) in our opinion). It has been established that the IFL of the steel used in our work is higher than its SFS for about 35%. This may be another important reason, besides compressive residual stress, responsible for improvement in fatigue property of shot peened specimens. Based on this concept, a method for calculation of fatigue strength of optimumly peened and/or peened and then ground specimens has been developed. Descriptors: Shot peening; Residual stress; Fatigue strength