Evaluation of component strength under corrosive conditions using a short crack fracture mechanics approach

摘要

Components used in oil and gas production often are exposed to dynamic loads in a corrosive environment. A crack initiation caused by high load frequencies has to be avoided, since component failure can arise in short-terms. So there is a need to perform an analytical strength assessment which incorporates the effects of corrosion but common guidelines do not include this effect.This paper presents an approach to determine the loss of fatigue strength due to a special type of corrosion, called pitting corrosion fatigue (PCF), the interaction of pitting corrosion and fatigue. The basic idea of this approach is to determine the remaining fatigue strength σ_(DR) of the component due to the size of the corrosion pits through using short crack fracture mechanics. According to Fujimoto [3], stresses with distance a_s to the surface are used to calculate σ_(DR). In order to validate the proposed approach, experiments have been carried out. The results of these were then compared with the short crack fracture mechanics approach and showed a general applicability of this approach.