Investigation of erosion-corrosion behavior of Q235B steel in liquid-solid flows

Abstract

This work aims to investigate the erosion-corrosion behavior of Q235B steel in liquid-solid two-phase flows. The weight loss rate, surface morphology and electrochemical parameters of Q235B steel at different temperatures (20 °C, 30 °C, 40 °C) and flow velocities (6 m/s, 7 m/s, 8 m/s, 9 m/s, 10 m/s) were studied separately. The results show that the weight loss rate of Q235B steel specimens after erosion-corrosion increases with increasing flow velocity and temperature. For the erosion-corrosion process, the corrosion rates of specimens increase with increasing flow velocity. The results of surface morphology show that the circular pits with clear edges are distributed randomly over specimen surface at low flow velocity, but the pit edge becomes vague at high flow velocity. With temperature increasing, the erosion-corrosion damage became serious as shown by the aggregation of large and small pits on specimen surface. The working mechanism of erosion-corrosion is found to vary with flow velocity and temperature. The relationships among erosion-corrosion components are quantitatively represented and show that synergy dominates the progress of material loss. Corrosion enhances erosion that is a dominant component in the synergy. The inactions of erosion-corrosion can be described by ‘‘synergistic’’ and ‘‘additive’’ behavior. The results show that “additive” effect becomes more significant with increasing flow velocity but decreases with increasing temperature, while “synergistic” effect is not sensitive to flow velocity and temperature.