Jivkov's articles
The role of strain-induced passivity breakdown in corrosion crack initiation
Abstract
Corrosion crack nucleation and growth are modelled as a moving boundary problem. The model incorporates
three physical processes – dissolution, passivation and straining – into a continuum mechanical framework.
The dissolution triggers surface advance; the passivation restrains the access of the environment to bare metal;
the deformation causes for passivity breakdown. Plane cracks nucleating from surface pits in an elastic-plastic
material body under fatigue load are considered. The problem is solved using a FEM program and a moving boundary
tracking procedure. The model simulates how cracks form and grow in a single continuous course. The geometry of
the developed cracks is found independent of the initial pit size. Plasticity is found to influence the curvature
at the tip of the nucleated corrosion cracks. The most important evolution length parameter, the width of the
corrosion crack, is found to depend on the size constraints of the tracking procedure. It is concluded that the
model is deficient for determining all length scales observed in reality. Physical processes to be considered
in an advanced model are proposed and discussed.