Wear and Corrosion Behavior of High-Cr White Cast Iron Alloys in Different Corrosive Media

Abstract

This study aims to investigate the effect of Cr/C ratio on wear and corrosion behavior of a group of high-Cr white cast iron (HCCI) alloys. Three different alloys of HCCI with different chemical compositions were tested against 3.5 % NaCl, 0.5 M H2SO4, and 0.5 M NaOH solutions as corrosive media. Electrochemical polarization technique has been used to determine the corrosion current density. The microstructure characteristics of HCCI alloys were analyzed by using optical microscope, SEM, EDS, and XRD. XRD analysis reveals that the microstructure of the HCCI alloys is composed of a network of chromium-rich carbides (M7C3) in an austenitic matrix. The abrasive wear resistance of HCCI alloys was found to be rely on their chemical composition and microstructure. The corrosion resistance of the HCCI alloys strongly depends on the Cr/C ratio and the ratio of chromium content in the M7C3 carbide to that in the matrix (CrM7C3/Matrix). The experimental results of this study showed that the alloy HCCI-2 with the lower Cr/C ratio exhibited the lowest abrasive wear loss while the alloy HCCI-1 with higher Cr/C ratio exhibited the highest abrasive wear loss. On the other hand, the HCCI-1 alloy was the most corrosion resistant and revealed the lowest current density. In addition, the corrosion current density of all specimens is elevated in 0.5 M H2SO4 solution in comparison with 3.5 wt% NaCl and 0.5 M NaOH solutions.