Original Article

Influence of Cu and Sn on the microstructure and properties of antibacterial ferritic stainless steel

¹ School of Metallurgy, Northeastern University, Shenyang City 110819, Liaoning Province, China
² School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan City 430081, Hubei Province, China

^* e-mail: 18524407363@163.com

Received: 16 February 2023
Accepted: 9 January 2023

Abstract

The influence of Cu and Sn on the microstructure, mechanical properties, corrosion resistance, and antibacterial properties of 430L ferritic stainless steel has been investigated by using Thermo-Calc calculations, EPMA (electron probe microanalysis), TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy). Vichers hardness tests, potentiodynamic polarization, and antibacterial tests were also performed. For a copper content of 1.5 wt.%, the results showed that aging treatments at 600 °C, 700 °C and 800 °C are conducive for the precipitation of an ε-Cu phase in the 430L ferritic stainless steel. It was also found that the ε-Cu phase was composed of almost pure Cu (with a the content of 98.6–99.7 wt.%). Thermo-Calc calculations showed that there was only a very small amount of Fe, Cr, and Mn in the ε-Cu phase. Moreover, the ε-Cu phase was found to substantially coarsen with an extension of the aging time. The size of ε-Cu phase increased from a few nanometers to hundreds of nanometers, and the number of ε-Cu phase decreased gradually. Furthermore, the antibacterial rate of the 2^# (430L − 1.5 wt.% Cu) and 3^# steel (430L − 1.5% Cu − 0.4 wt.% Sn) samples increased significantly with an extension of the aging treatment time, and the antibacterial rate of the 3^# steel was higher than that of the 2^# steel sample. The antibacterial rate reached as high as 91.60% and 97.37%, respectively, for an aging time of 79,200 s.