Erosion–corrosion resistance of Mo–Ti- and Ni–Cr–Mo-alloyed medium-carbon martensitic steels: a critical analysis of synergistic effect of erosion and corrosion

Grain refinement renders Mo–Ti-alloyed medium-carbon martensitic steel to exhibit high hardness, high strength, and good toughness, but the erosion–corrosion resistance of steel in a corrosive slurry environment is not known. Mo–Ti-alloyed medium-carbon martensitic steel is compared with Ni–Cr–Mo-alloyed medium-carbon martensitic steel, and the erosion–corrosion resistance of those two steels under impingement by NaCl solution with gravels has been investigated. Three components, pure-corrosion rate, pure-erosion rate, and synergistic effect of erosion and corrosion (SEEC) of erosion–corrosion rate, were quantified. The pure-corrosion and pure-erosion rates of Mo–Ti-alloyed steel were higher than those of Ni–Cr–Mo-alloyed one; however, its erosion–corrosion rate was relatively lower because of a weak SEEC. Surface plastic deformation and work hardening due to gravel impingement were the essential reason for SEEC, which could be reduced by grain refinement, and consequently, Mo–Ti-alloyed steel with finer grains had better erosion–corrosion resistance. Grain refinement could be an effective way to improve the erosion–corrosion resistance of martensitic steels.