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.

Automated summary

This study compares the erosion-corrosion resistance of Mo-Ti-alloyed medium-carbon martensitic steel with Ni-Cr-Mo-alloyed medium-carbon martensitic steel under impingement by NaCl solution with gravels. It is found that the erosion-corrosion rate of Mo-Ti-alloyed steel is relatively lower, which is due to the reduction of synergistic effect caused by surface plastic deformation and work hardening.