This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Continuous Observation of Cavity Growth and Coalescence By Creep-Fatigue Test in Sem
Published April 15, 1996 by Institution of Mechanical Engineers in United Kingdom
Event: Sixth International Conference on Creep and Fatigue Design and Life Assessment at High Temperature
In this study, static creep and creep-fatigue tests with tensile hold-time were conducted on a SUS304 stainless steel by using a high temperature fatigue testing machine combined with a scanning electron microscope (SEM), and cavity growth and coalescence behaviors on surface grain boundaries were observed continuously by the SEM. As a result, it was found that cavities nucleated at random and grew preferentially on grain boundaries in a direction nearly normal to a stress axis. Under creep condition, the cavities grew monotonously while remaining an elliptical shape. On the other hand, under creep-fatigue condition, the cavities grew with the effect of local strain distribution around the grain boundary and micro cracks of one grain-boundary length were formed by coalescence of cavities. Also, cavity nucleation and growth rates for creep fatigue were more rapid than those for static creep and the constrained cavity growth model coincided well with the experimental data for creep.