Full factorial, microscopic and spectroscopic study of erosion-corrosion of AISI 1018 steel elbows in potash brine-sand slurry

Carbon steels are commonly used in minerals processing facilities, but their susceptibility to erosion-corrosion attack can lead to pipe leakage. Hence, the development of a predictive model to estimate equipment lifespan has become essential. In this study, an empirical linear regression model was developed to predict the erosion-corrosion rates of carbon steel elbows in potash brine-sand slurry using full factorial experimental analysis. It was found that velocity, particle concentration and the interaction between them are statistically significant, with velocity having the most significant influence on erosion-corrosion rate. Microstructural examination of the elbows that suffered erosion-corrosion damage indicated cutting, horseshoe-shaped depressions and pitting corrosion as the primary forms of damage to the elbow surface. Analysis of the corrosion products using XPS and Raman spectroscopy showed the presence of γ-FeOOH, α-FeOOH, α-Fe2O3 and Fe3O4. •Erosion-corrosion rate of the elbow increases with the increase of velocity and particle concentration.•The model successfully predicted the erosion-corrosion rate of the elbow under the specified flow conditions.•Flow velocity had the highest influence on the material removal rate of the elbow.•Damage to the elbow surface was caused by grooving, cutting and dissolution of the elbow.•Corrosion products after erosion-corrosion damage are composed of γ-FeOOH, α-FeOOH, α-Fe2O3 and Fe3O4.