Development of a finite element model for simulation and prediction of mechanoelectrochemical effect of pipeline corrosion

In this work, a finite element model was developed to study mechanoelectrochemical effect of pipeline corrosion through a multiphysics field coupling technique. The modeling results, i.e., corrosion potential and corrosion current density, are well consistent with experimental measurements on pipeline steel in a near-neutral pH solution. It is demonstrated that, while a tensile strain enhances stress uniformly through pipe wall, an increasing depth of corrosion defect results in a concentrated stress at the defect center only. When the corrosion defect is under an elastic deformation, there is no apparent effect of mechanical-electrochemical interaction on corrosion. However, when the applied tensile strain or the geometry of corrosion defect is sufficient to cause a plastic deformation at the defect, the local corrosion activity is increased remarkably. Corrosion at the defect is composed of a series of local galvanic cells, where the region with a higher stress, such as the defect bottom, serves as anode, and that under lower stress, such as the defect sides, as cathode. The locally accelerated corrosion at the defect center can be further enhanced as the corrosion defect deepens.