Deterioration Behavior of Steel Passivation Films in a Nano Perspective: Effect of Shear Stress.

Corrosion of reinforcement is one of the key problems affecting the durability of concrete structures. This phenomenon begins with the deterioration of the passivation film. Regrettably, the underlying microscopic mechanisms governing the deterioration process of passivation films under stress remain inadequately investigated. In this study, we employ molecular dynamics (MD) simulations to model the deterioration of passivation films with different defects and subjected to varying shear stresses. Notably, the presence of defects considerably compromises the passivation film's shear stress resistance. Conversely, the ideal passivation film exhibits robustness against shear stress, manifesting deformation only under high-stress conditions. Moreover, we observe that the defective film only maintains partial stability by dislocation sliding under low stress in the actual simulation. Nevertheless, as stress levels escalate, the dislocation sliding mechanism ceases to be effective, leading to interlayer deterioration and overall deterioration of the structure.