A novel understanding of dislocation density effect on the corrosion resistance of 316L stainless steel with passive film nucleation growth kinetic calculation

Abstract

This work illustrates the relationship between dislocation density and corrosion resistance of 316L stainless steel based on passive film nucleation growth kinetics calculations. Contrary to previous reports, the increase in high dislocation density zones is an important feature associated with the passivation behaviour of stainless steel. With the expansion of the high dislocation density region, the passivation current density decreases from 1.48 × 10⁻⁵ A·cm⁻² to 1.35 × 10⁻⁷ A·cm⁻², and the corrosion resistance of the stainless steel increases. The results of TEM showed that the thickness of the passive film increased from 3 ∼ 4 nm to 6 ∼ 7 nm after 72 h of immersion after the dislocation density was increased. Based on the laboratory results, a theoretical validation was carried out by means of a computational model of passive film nucleation and growth kinetics. The results show that the number of nucleation sites can be increased by increasing the dislocation density, resulting in faster passive film growth. Te and La improve the stability of the passive film mainly by hindering the dissolution of the elements. La does not exist stably in the passive film but can be preferentially deposited to increase the nucleation sites to promote the growth of the passive film.