Cu-bearing, martensitic stainless steels for applications in biological environments

Abstract

Precipitation of Cu in stainless steels disturbs the passivating oxide layer and intensifies the release of Cu ions in biological environments which act toxically against the microorganisms. The phenomenon allows promisingly the production of age hardenable, Cu-bearing stainless steels with antibacterial property, suitable for fabrication of medical, home and environmental appliances. In the present study, aging behavior, microstructure and antibacterial performance of AISI 410s stainless steel with different amounts of Cu addition (nominally 1, 3 and 5wt%) were investigated. Microhardness, X-ray diffraction, optical, scanning and transmission electron microscopy were used. After solution annealing at 1330K and oil quenching, the AISI 410s steel showed dual phase martensite-ferrite microstructure. It was found that increasing of Cu content decreases ferrite content remarkably. Both of martensite and ferrite phase constituents showed remarkable precipitation hardening after aging at 773K. Their age hardenability increases with increasing of Cu content. Antibacterial performance was evaluated against Escherichia coli and Staphylococcus aureus bacteria, the common pathogens of human disease and food poisoning. Addition of 3wt% Cu gives appropriate age hardenability and antibacterial performance.