The effect of Cr addition on microstructure and tribological properties of iron aluminide cladding produced by GTAW process

In this study, formation of Fe 3 Al and (Fe,Cr) 3 Al intermetallic compounds and the effect of Cr on microstructural and mechanical properties of Fe-Al cladding system such as hardness and wear resistance, were evaluated.For this purpose, first, iron and aluminum powders were mixed in the first series without chromium powder and in the second series with the addition of chromium powder in high energy planetary ball mill, and Fe 3 Al and (Fe,Cr) 3 Al intermetallic compounds were synthesized.The preplaced powders were cladded on the surface of CK45 steel using gas tungsten arc welding process.The microstructure, formed phases and properties of the cladded layers were studied by optical microscope, scanning electron microscope, X-Ray Diffraction, micro and macro hardness, energy dispersive X-ray spectroscopy (EDS) and pin on disk wear test at 25, 250, and 500C temperatures.It was found that the microstructure of Fe-Al binary cladding contained Fe3Al dendrites with non-epitaxial growth.This non-epitaxial growth results from the difference in the chemical composition of the coating and the substrate at the interface between the coating and the substrate, which has caused the formation of new crystals at the interface.However, the microstructure of Fe-Al-Cr ternary cladding contained martensitic blades within (Fe,Cr) 3 Al matrix.The results of hardness tests revealed that the hardness of ternary cladding is twice as compared with the binary cladding (30 and 60 HRC for binary and ternary claddings, respectively).Also it was found that the presence of Cr element in Fe-Al cladding improved the wear resistance of deposited layers.The predominant wear mechanism of Fe 3 Al pin was adhesive, while for (Fe,Cr)3Al pin moreover adhesive wear, micro-plowing abrasive wear was also seen.The mass losses of both pins were maximum at ambient temperature and minimum at temperature of 500 o C.