Effect of Copper on Passivity and Corrosion Behavior of Fe-xC-5Cu Alloy

Abstract

The correlation between corrosion behavior rate of annealed Fe-xC-5Cu alloys and their microstructure and phase composition is presented. The metallurgical analyses, including, X-Ray diffraction (XRD), the scanning electron microscopy (SEM) with energy dispersive analysis (EDX), and induction hardening characterization are conducted to study the Fe-C-Cu alloys. Corrosion parameters in H₂SO₄ 1N solution have been established by carrying out electrochemical studies such as potentiodynamic (Tafel polarization and linear polarization, LP) and electrochemical impedance spectroscopy (EIS). The coupled effect copper/microstructure is discussed. Alloying Cu showed a beneficial effect on hypoeutectoid steel and harmful effect on hypereutectoid steel. The improved corrosion resistance is related to cementite morphology and by a copper dissolution/re-deposition process.

Keywords: Corrosion; Copper; cementite; EIS; Passivation; Hardness.