A modified Beremin model to simulate the warm pre-stress effect

Abstract

Starting from the pioneering work of Beremin (Met. Trans. A 14A (1983) 2277), a modified Beremin model is proposed. As a result of temperature effect on mechanical fields heterogeneity at the micromechanical scale, an apparent temperature dependence of the macroscopic cleavage stress is first introduced to fit correctly the brittle to ductile transition. Then, the classical Beremin–Weibull fracture probability expression is extended to take account of non monotonic thermomechanical loadings. The modified Beremin model is applied to warm pre-stress (WPS) tests performed on low alloy ferritic steel compact tension specimens (see IAEA Specialists’ meeting, Rockville (2000)). Apart from ‘load–unload–cool–fracture’ (LUCF) cycles, for which additional investigations are needed, these simulations are in good agreement with experiments provided that an additional microcrack propagation condition is introduced, namely, necessary slip activity. This additional condition is consistent with the classical Beremin model restricted to monotonic loading paths.