Variations in microstructure of high chromium cast irons and resultant changes in resistance to wear, corrosion and corrosive wear

摘要

High chromium cast irons are widely used in many industrial machineries and facilities that are attacked by wear in dry condition or corrosive environments. Appropriate selection of materials with optimum microstructure can extend their service life and thus minimize the maintenance cost. For the white cast irons, their resistances to wear and corrosion largely depend on the concentrations of chromium and carbon. In this study, microstructures of a series of high chromium white cast irons (wt%Cr=30, wt%C = 1, 2,3,4,5 and 6, wt%Mn = 2, wt%Si = 0.5, balanced by iron) were cast and characterized, and corresponding resistances to wear, corrosion and corrosive wear were evaluated, respectively. It was demonstrated that the corrosion resistance of these high chromium alloys largely depended on the Cr concentrations in the matrix and the volume fraction of carbides, while the wear resistance was dominated by the volume fraction of carbides. Efforts were made to correlate the variations in performance of these alloys during wear, corrosion and corrisive wear tests with their microstructures.