Microstructure and wear resistance of Cr powder alloying layers on cast iron

The grey cast iron was alloyed by light beam remelting the preplacing layer of Cr powder. The microstructure and phase of alloying layers were analyzed by SEM,EDS and X-ray diffraction. The ring-block wear test was use to evaluate the wear resistance of alloying layers. The results show that the wear resistance of Cr powder alloying layer is greatly higher than that of grey cast iron. The wear resistance is heightened with the increases of preplacing mass of Cr powder,and the wear mechanism changes from furrow and scratch to surface plastic deformation. The reason is that with the increases of preplacing mass of Cr powder,the eutectic matrix of α-(Fe,Cr) rich in Fe+Cr7C3 in alloying layer is replaced by the eutectic of α-(Fe,Cr) rich in Fe+Cr23C6,then replaced by α-(Fe,Cr) ferrite rich in Cr.