Full factorial investigation on the erosion–corrosion resistance of UNS S31603

The interactions that occur when erosion and corrosion act simultaneously are extremely complex and are often difficult to interpret. These interactions generate either a synergistic or antagonistic material loss effect for a particular material in a certain environment. The level of interaction between impact energy, number of impacts, fluid temperature, material properties, fluid flow and electrochemical properties severely complicates the analysis of erosion–corrosion wear rates. This paper investigates the interaction between the main parameters influencing erosion–corrosion. A combination of statistical analysis and interaction contour plots has been employed to obtain in-depth understanding of the variables influencing erosion–corrosion, namely particle velocity, sand size, sand concentration and fluid temperature. An empirical equation has been derived from test results to describe the relationship between the test parameters. Analysis of the residuals versus predicted erosion–corrosion shows a normalized distribution and thereby confirms the suitability of this model. Velocity was found to have the strongest influence on erosion–corrosion rate followed by sand concentration, temperature and finally sand size, which had the least significant effect. SEM surface features show that the increase in sand concentration causes the surface to be covered with a higher number of impact craters and lips indicating a linear relationship between the two. The SEM micrographs also show that the increase in sand size produces deeper craters and more prominent lips compared to fine sized particles where the particles tend to graze the surface without sufficient kinetic energy to plastically deform the material surface.