The effects of Cr/Mo micro-alloying on the corrosion behavior of carbon steel in CO2-saturated (Sweet) brine under hydrodynamic control

Abstract

The effects of micro-alloying of plain carbon steel with Cr and Mo on the corrosion behavior in CO2-saturated (sweet) brine (0.5 M NaCl, pH 6.6) environment, under hydrodynamic conditions, at 80°C were investigated. Crystalline siderite/chukanovite scales formed on all the alloys. Analysis of potentiostatic current transient data suggest that there exists a synergistic interaction between Cr and Mo, which induces more rapid crystallization of the scale compared to Mo-free steels. Increasing the Mo content also suppressed the transport-dependent dissolution current passing through the initially-present amorphous surface film. TEM images of the FIB-sectioned corrosion scales confirm that the corrosion scale formed on 1Cr0.7Mo is comparatively thinner and yet offers greater protectiveness when compared to the plain carbon steel.