Ab Initio Monte Carlo Simulations of the Acidic Dissolution of Stainless Steels Effect of Mechanical Deformation

Abstract

This work is devoted to the Monte Carlo (MC) simulation of the acidic dissolution of mechanically deformed stainless steels (SS). Ab initio relaxation techniques are first used to calculate the bonding energies between atoms as a function of the interatomic distance. Dissolution kinetics of pre-deformed SS structures are then evaluated by means of an MC algorithm. Calculations show that the dissolution probability of surface atoms depends strongly on the strain field near the surface, compressed zones being found to dissolve more rapidly than extended ones. Mechanically induced defects, such as dislocation loops, were also investigated and shown to form preferential dissolution pathways due to the high levels of deformation and to significantly enhance the dissolution kinetics. Last, adding alloying elements is shown to increase the weakening effect of the strain field, regardless of the deformation mode. The addition of molybdenum for instance, known to improve the anodic dissolution resistance, may become less effective in deformed stainless steels.