Development of Low Cost Corrosion Resistant Fe-Cr-Mn-Cu White Cast Irons

摘要

High silicon, M-Resist and high chromium irons are the most frequently used corrosion resistant alloy cast irons. High silicon cast irons have poor mechanical strength while Ni-Resist irons suffer from graphitic corrosion. Ni-Resist irons and high chromium-molybdenum irons are very expensive due to high cost of scarce elements nickel and molybdenum. Fortunately indigenously available elements, manganese and copper, have many characteristics similar to nickel and thus can be utilized for substituting nickel partly or fully. The fact that difference in electrochemical potential between austenite and carbide is less than that between austenite and graphite strengthened the basis of developing low cost corrosion resistant white irons based on Fe-Cr-Mn-Cu system.In the investigated alloys, Fe-3.7 percent C-7 percent Cr-10 percent Mn-3 percent Cu, dispersed second phase precipitated from the austenite matrix, on heat treating, adversely influenced corrosion resistance of the alloys. However, corrosion rates in 5 percent NaCl solution were found comparable to that of Ni-Resist irons.