关键词: 管线钢, 　腐蚀缺陷, 　应力腐蚀, 　有限元模型

Abstract: Due to the effects of service environment, corrosion defects inevitably appear on pipeline surface, which will cause stress concentration and promote crack nucleation. In this study, a coupled stress and electrochemical multi⁃physical field model for predicting the morphological development of corrosion defects was established based on the finite element method. The time dependence of stress corrosion behavior and corrosion morphology of X70 pipeline steel in sea mud simulated solution were studied by using the established model via deformation geometry and dynamic mesh technology. The results showed that the mechanical⁃electrochemical effect played an important role in the nucleation of stress corrosion cracks. The smaller the width of corrosion defects, the greater the stress concentration, the negative shift of the electrode potential and the higher the corrosion rate. With the increase of the operating pressure, there was a large area of high stress concentration area in the bottom of the corrosion defect, and the area of metal loss caused by corrosion increased.

Key words: Pipeline steel, Corrosion defect, Stress corrosion, Finite element model