The Microstructure, Antimicrobial Properties, and Corrosion Resistance of Cu‐Bearing Strip Cast Steel

Abstract

The antimicrobial and corrosion properties of Cu‐bearing steels fabricated via simulated strip casting are examined. Two distinct microstructures are observed: those alloys with Cu concentrations below 5 wt% retain the Cu in solid solution, and those alloys with high Cu concentrations form a two‐phase structure containing an austenite matrix and large Cu‐rich precipitates. The alloys display antimicrobial properties against Escherichia coli, causing up to 65% of bacteria death upon direct contact for 24 h. Surface analysis by X‐ray photoelectron spectroscopy indicates that after exposure to bacteria, the surface passive film remains enriched in Cu and its oxides, and immersion studies confirm gradual release of Cu ions from the passive film in a wet environment. Corrosion testing of the Cu alloys demonstrates that when the copper is retained in solid solution, the corrosion behavior is not markedly different from the copper‐free reference alloy. However, in those higher‐concentration alloys that contain Cu‐rich precipitates, the anticorrosion performance of the steel is greatly deteriorated, with the corrosion mechanism changing from pitting corrosion to selective corrosion.