Microstructure and wear properties of Fe-Cr-C and Fe-Cr-Nb-C clads on carbon steel by TIG surfacing process

In the present study, the surface of St52 steel was alloyed with preplaced Fe-Cr-C and Fe-Cr-Nb-C powders by using a tungsten-inert gas (TIG) heat source. The microstructure and phase composition of the alloyed surfaces were investigated using optical microscopy, scanning electron microscopy (SEM) and X-ray diffraction. Microhardness measurements were performed across the alloyed zone. The tribological behaviour of the coatings was evaluated using dry sliding wear tests at room temperature. It was found that the as-deposited coatings consisted of high volume fraction of carbides (Cr7C3, NbC). The Nb free and Nb-contained clad coatings both exhibited an excellent wear resistance compared to 0.22% C carbon steel under dry sliding wear tests. The wear resistance of Nb-contained clad coating was higher than that of the Nb-free clad coating because the hard carbide NbC was distributed in clad coating which increased the wear resistance of clad coating under dry sliding wear test. No cracks were found in the coatings.