Laser cladding of Ni-Cr3C2/(Ni+Cr) composite coating

Laser clad coatings of Ni alloy as well as a composite made from 50 wt% Cr3 C2 particles coated with a Ni-Cr alloy and Ni-base alloy on steel 1045 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD ), energy-dispersive X-ray analysis (EDX) and microhardness tests, respecti vely. The effects of microstructure obtained by varying the laser process p arameters on the microhardness profile along the depth were studied in the two kinds of clad layers. The results showed that a strengthened surface la yer was produced on steel 1045 by laser incorporation of Cr3C2 particles, w hich increased the hardness of the surface layer by 350-400 HV. The presenc e of undissolved Cr3C2 particles, the formation of dense dendrites surround ed by a fine eutectic and the precipitation of Cr7C3, Fe-23(C, B)(6) compou nds during rapid solidification after the laser treatments were thought to be the main factors for the strengthening of the composite coating. (C) 199 8 Elsevier Science S.A. All rights reserved.