The effects of prestressing overload on dow cycle fatigue and fatigue crack growth rates da/dN of titanium alloy TC-11 and Ni-base superalloy GH33A for gas turbine disks were investigated at room temperature and 633K. The experimental results show that the low cycle fatigue crack initiation life is increased by prestressing overload treatment within the range of low cycle fatigue life 5×103 to 5×104

but the effect of the prestressing overload on fatigue crack propagation life Np is not obvious. In addition

an empirical expression is formulated to estimate the fatigue life of side edge notched (SFN) specimen under prestressing overload as Sm（Nf/r） = c. When this expression is employed to estimate the fatigue life of a notched specimen prestressed

it is only necessary to know the conventional fatigue S-N curve.