The influence of the stress ratio on fatigue crack growth in a cermet

The fatigue crack growth behavior in a cermet was investigated as a function of the stress ratio, R. At the higher Kmax values the fracture path was through the cermet particles as well as through the binder phase. At low growth rates the fracture path was primarily through the binder phase. As a result the fatigue crack growth process, at a growth rate of l0−7 m/cycle the rate was influenced by Kmax, and to a lesser extent by the R value, whereas at a growth rate of 10−11 m/cycle the growth rate depend upon ΔK as well as the R value.