Effect of carbon content on the erosion-corrosion behavior of low-alloy martensitic steels under simulated marine dredging slurry

In this work, five low alloy martensitic steels (362.6∼709.2 HV) with different carbon content (0.1∼0.6%) and Q355 comparative steel (171.8 HV) were designed to study the erosion-corrosion behavior under simulated marine dredging slurry. The mechanism of pure erosion, pure corrosion, and their synergistic effect were analyzed by observing the morphological characteristics of the surface and subsurface. Results showed that the erosion was the main component that constitutes total erosion-corrosion damage (47.4∼68.4%), followed by synergistic effects (27.3∼38.4%). The erosion component gradually decreased with the increase of carbon content, while the synergistic effect component first decreased and then increased, which was attributed to the dominant factor transitioning from hardness to corrosion resistance. For low hardness steel (0.1C steel and Q355), cutting and extrusion were the main damage characteristics. However, erosion-corrosion craters appeared when the carbon content in martensitic steel exceeded 0.2%, which may pose challenges to pipeline transportation efficiency and safe operation. Moreover, increasing hardness did not improve erosion-corrosion resistance linearly, as transverse cracks appeared after repeated sand impacts within the moderate hardness range (460-600 HV). Work hardening played a significant role in enhancing erosion-corrosion resistance for steels with initially lower hardness. The above results provided important guidance for the design and selection of steels under marine dredging conditions.