Stress Relaxation Resistance For Improved Fatigue Performance Of Shot Peened Tool Components

Author:  Medvedeva, Bergstr
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008083
Year of Publication:  2008
Abstract:  
ABSTRACT Shot peening is an extensively used process in the production of mechanical components to improve their fatigue strength at ambient temperature. At higher working temperatures of some mechanical components, e.g. from 300 to 600..C, the influence and behaviour of the compressive residual stresses are more uncertain, since they tend to relieve at higher temperatures. The response to shot peening induced residual stresses of low alloyed and hot work tool steels was evaluated with respect to stress relief heat treatments and isothermal high temperature fatigue testing. Not only the residual stresses, but also the material substructure and its dislocation characteristics are of importance. Dislocation structures were determined using X-ray diffraction to explain the preference of the different steel grades. Also, results obtained from bending fatigue testing at ambient temperature of tool components after shot peening and stress relief heat treatments demonstrated the different ability of retaining the fatigue strength. KEY WORDS Shot peening, Fatigue strength, Isothermal fatigue, Residual stress, Stress relaxation