The erosive wear in an alkaline slurry containing alumina particles of three typical engineering materials, the mild steel BS 6323 (Fe-C), the AISI 410 stainless steel (Fe-Cr-C), and the AISI 304 stainless steel (Fe-Cr-Ni), was carried out, by means of rotating cylinder, three-electrode erosion-corrosion test, with a view to investigation into the roles of the typical elements and the mechanical and chemical properties in the erosive wear under simultaneous controlled corrosion. The total weight loss of erosion-corrosion was obtained by precision weighing and the result was compared and interpreted, for each material, by a full microscopical examination of the erosion-corrosion scars using scanning electron microscopy (SEM). It was found that the overall performance under erosion-corrosion in an descending order was the stainless steels AISI 304, AISI 410, and the mild steel, although the precise difference in performance was dependent upon the process conditions. Such a ranking of performance was not in total consistence with that expected only from the mechanical or the chemical property differences of the materials concerned. The individual contribution of each erosion and corrosion process was thus further separated through corrosion charge conversion using the Faraday's second law and the results were interpreted by discussion, on basis of the experimental and microscopical evidences, of the main factors that influenced the mechanical and wear behaviour, in conjunction with those influencing corrosion and passivity. Finally, schematic diagrams were proposed to outline the typical erosion and corrosion features thus obtained for all the three materials during erosion-corrosion.