The impact of alloying element Cu on corrosion and biofilms of 316L stainless steel exposed to seawater.

Copper-containing stainless steel (SS) has been reported to mitigate biofilms in industrial and clinical environments. However, the impact of copper released from copper-containing SS in natural seawater on biofilms and corrosion is still unclear. In this study, three kinds of 316L SS were immersed in natural seawater for 6 months, and the pitting depth decreased in the order: 316L-Cu SS (annealed) > 316L SS > 316L-Cu SS (aged). The biofilm thickness and number of sessile cells on the surface of 316L-Cu SS (annealed) and 316L SS were similar but notably greater than those of 316L-Cu SS (aged). Furthermore, the results of the community analysis indicated that the addition of copper in 316L-Cu SS (aged) reduced the diversity and richness of the microbial community, resulting in a significant reduction in the number of genera constituting the biofilms. Copper ions exhibit a broad-spectrum bactericidal effect, effectively reducing the abundance of dominant populations and microbial genera in the biofilms, thereby mitigating pitting corrosion induced by microorganisms. In addition, the PCoA scatter plot showed that time also played an important role in the regulation of microbial community structure.