OS12W0391 Advanced creep damage analysis of low-alloy steel welds considering the microscopic damage progress

Abstract

A simulation method for multi-site creep damage at the fine-grain heat-affected zone of welds involving high energy piping consisting of low alloy steel was proposed on the basis of the combination of elastic-creep FEM analysis and random fracture resistance modeling of the materials. First, the initiation and the growth driving forces of small defects taking into account the dependence on stress and temperature were concretely determined based on microscopic observation of the damage progress of the material. Then, a simulation procedure combining the stress distribution from elastic-creep FEM and the random fracture resistance model was proposed, and this procedure was applied to the simulation of the microscopic damage progress in a welded joint model test and in actual power piping. The results in terms of the simulated number density of small defects throughout the wall thickness matched well with the observed results.

Life prediction of repaired welds in a pressurised CrMoV pipe with incorporation of initial damage

“…The initial cavitation site is generally just below the outer surface and gradually extends through the Type IV microstructural region to the inner surface as a function of time, e.g. see Kawashima et al [16]. In addition, it extends back to the outer surface allowing detection using conventional inspection techniques.…”