Modelling for Creep Cavitation Damage and Life of Three Metallic Materials

Abstract

Metallic structures operating at high temperatures can have creep as a life-limiting mechanism. The limit can arise by nucleation and growth of creep cavities that eventually merge becoming the leading damage of the fracture mechanisms. Understanding and modelling for creep cavitation can therefore help in prediction of structural safety and condition of such structures. The present paper will introduce a new model to predict creep cavitation damage so that the associated creep strain is also modelled out of the predictive expression without losing accuracy in the time to critical damage and corresponding residual life. The model was verified for OFHC copper, low-alloy 0.5CMV steel and higher-alloy X20 steel, to cover a wide range of polycrystalline metals and their microstructures. The new model performed as well as or better than the classical approach which requires access to measured strain. The model was applied to predict creep cavitation damage from time, stress and temperature as predictive variables.

Accurate determination of creep cavity nucleation rate and growth rate with considering the partial coalescence prior to rupture and its impact on creep lifetime prediction

“…Selecting suitable experimental techniques and modelling approaches is crucial for developing a robust model of microstructural cavitation damage during creep. Experimentally, according to [10], [11] microscopic techniques like SEM are valuable for examining creep damage and cavitation data, but they are limited to two-dimensional representations. Fortunately, Xsynchrotron tomography cavitation data can overcome this limitation [12], and facilitate displaying the cavitation data from a volumetric or three-dimensional perspective, revealing the chronological sequence of the damage evolution [13].…”