The Chaboche type UVP material model1,3,49 is adopted in this work, to describe the high temperature, cyclic visco-plastic behavior of FV566 steel. The basis for choosing such a model is that the overall high temperature cyclic behavior is a combination of rate-dependent cyclic plasticity and temperature-dependent creep, which can be well described by Chaboche UVP model, in which, the total deformation is simply assumed to consist of elastic and inelastic (visco-plastic) components, where the latter is a combination of creep and cyclic plasticity. Hence, under small-strain deformation, the total strain tensor,, is composed of both a small recoverable elastic strain tensor,, and a large irreversible visco-plastic strain tensor,, such that: