Investigation of Erosion-corrosion of Carbon Steel Elbow in 3.5% Sodium Chloride Containing Quartz

Abstract

In this study, the erosion-corrosion (E-C) behavior at different locations of a 90° horizontal elbow was investigated under the condition of liquid-solid two-phase flow by weight loss measurement, electrochemical measurement and surface analysis through a loop experimental device. Besides, a quantitative analysis was performed on the pure corrosion rate, the pure erosion rate, the changed amount of corrosion rate caused by erosion, and the changed amount of erosion rate caused by corrosion and their percentages in the E-C rate, in an attempt to reveal the damage mechanism of metal materials. There were different E-C rates, electrochemical characteristics and surface morphologies at different locations of the elbow; the areas with severe E-C appeared at the bottom of the elbow and the outer part of the elbow outlet; surface morphologies were mainly presented as pits and grooves. In the total E-C rates, the percentages of pure corrosion rates and pure erosion rates were very small, while that of E-C interaction rates were large, which demonstrated that the interaction between electrochemical corrosion and mechanical erosion was the main cause of damage to metal materials. In the E-C process, mechanical erosion and electrochemical corrosion can contribute to each other, with the former playing a dominant role and the latter playing a subordinate role.