Short Crack Fatigue Behaviour Of Nitrided And Shot Peened Steels

Author:  I. Fern
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008086
Year of Publication:  2008
Abstract:  
ABSTRACT The execution of shot peening of steels after nitriding is a compound treatment that has been not sufficiently investigated to assess how and when it can be useful to improve the fatigue beahviour of components. In this paper the fatigue threshold of two nitrided and shot peened steels is investigated by means of experimental rotating bending fatigue tests carried out on specimens containing a micro-hole, acting as a pre-crack. Due to the dimension of the pre-cracks, they were considered as short crack. After a critical discussion of the results in terms of residual stress, microhardness and inclusion rate, a fracture mechanics based approach is proposed to predict the fatigue threshold value of the stress intensity factor of nitrided and shot peened steels. The results are in good agreement with the experiments. KEY WORDS Nitriding, shot peening, residual stress, FWHM, fatigue threshold (