# Corrosion Behavior of Stainless Steel in Seawater in the Presence of Sulfide
## 1 Introduction
Moreover, [PERSON] [20] observed that the pitting corrosion of low-carbon steels in the polluted seawater of San Diego Harbor in California, SAD, was several times higher than the corrosion that normally occurs in clean seawater [20]. Although most of the published research results indicate a negative influence of sulfides on the corrosion of metals and alloys, there are also those showing the opposite influence, namely the positive effects of sulfides inhibiting corrosion under certain conditions by the formation of protective iron sulfide layers [21]. For instance, [PERSON] et al. found that sulfide film on the steel surface prevents pitting and the corrosion resistance increases with immersion time [22]. Stainless steels are widely used in marine structures, so the study of their behavior in seawater is of great interest. Austenitic stainless steel grades 304 and 316 have excellent ductility, good strength, nonmagnetic properties, good weldability, and very good corrosion resistance, so these materials find widespread practical applications [23; 24; 25; 26; 27]. Grade 304 stainless steel is commonly used as a material for marine fittings, while grade 316 stainless steel (UNS S31600/S31603--commonly referred to as marine stainless steel) is used in about 90% of marine applications. The high corrosion resistance of austenitic stainless steels is a consequence of the natural formation of a protective passive oxide layer on their surface with a high Cr content and a thickness of 1-10 nm [28; 29; 30]. Although the resistance of passive films to general corrosion is relatively high, they are susceptible to localized attack. Fitting corrosion is the most common form of electrochemical damage to stainless steel, caused by the local breakdown of the surface passive layer. The susceptibility of metals and alloys to pitting corrosion depends on factors such as temperature and environmental composition. As with chemical reactions, the rate of pitting corrosion increases with increases in electrolyte temperature. Indeed, a strong dependence of pitting potential on temperature has been found in previous studies on stainless steel,with higher pitting potentials observed at lower temperatures and lower pitting potentials at higher temperatures [31; 32]. The presence of impurities such as sulfides and sulfur oxides in seawater has a negative effect on the passivation kinetics of stainless steel [33]. It has been suggested that sulfide and chloride may act synergistically in the film, with the integration of sulfide into the passive film facilitating further infiltration by chloride and promoting the formation of pits at surface inhomogeneities [34]. [PERSON] [35] and later [PERSON] [36] proposed a mechanism by which sulfur species adsorbed on the pit surface maintain activity and retard repassivation, leading to the propagation of pits in stainless steels. [PERSON] et al. [37] found that the passive film in Cl\({}^{-}\) solution without sulfide has a variation of p/n semiconductor type, which can provide good protection for the film. However, the passive film in H\({}_{2}\)S-Cl\({}^{-}\) solutions exhibits only an n-type semiconductor behavior, which tends to attract anions to the film and impair its protective effect. The n-type semiconductor in H\({}_{2}\)S-Cl\({}^{-}\) solutions is caused by the sulfidation of oxides on the film. Although the mechanism of H\({}_{2}\)S-induced sour water corrosion of various alloys has been researched, some contradictory results and the high damage caused by corrosion in the presence of H\({}_{2}\)S provide the impetus for further research on this topic.