Effect of Nano-sized Cu-Rich Phase on Microbiological Corrosion Behavior of Cu and Ni-Added Steel for Oil Country Tubular Goods

The Cu-bearing antibacterial low-alloyed steel pipe is a new strategy to mitigate microbiologically influenced corrosion (MIC) for oil and gas industry. It can effectively alleviate the occurrence of bacterial corrosion, but cannot avoid the MIC totally. To enhance the resistance to MIC of Cu-bearing low-alloyed steel, the MIC behavior of a Cu and Ni-added experimental steel with different nano-sized Cu-rich precipitates was investigated. Results showed that the synergistic effect of antibacterial ability of nano-sized Cu-rich precipitates and protective Cu–Ni enrichment layer formed on the steel surface contributed to the good MIC resistance. Although the Cu-rich precipitates possessed antibacterial actively, they also increased the surface potential difference simultaneously, resulting in promoting MIC. The extremely fine and dispersed Cu-rich precipitates with high-density was the preferred microstructure to achieve better MIC resistance for the steel.