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High-chromium cast iron (HCCI) coatings with multicomponent carbides were prepared on low-alloy steel substrates using a laser cladding technique in this work. The microstructure and wear resistance of the coatings were characterized via optical microscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction and block-on-ring wear testing. Multicomponent carbides (Ti, Nb, Mo, W, V)C with an FCC structure and multicomponent compounds (Nb, Mo, W, V) (B,C) with an FCC structure were found in the microstructures of coatings after multielement doping. In addition, (Cr, Mo, W, V)23C6 compounds could be obtained by heat treatment. These multicomponent compounds were beneficial for obtaining coatings with an excellent hardness (60 HRC) and high wear resistance. This multielement doping method provides an effective modified method for preparing high-wear-resistance laser cladding coatings. [ABSTRACT FROM AUTHOR]

Highlights: The structural and elastic properties of (Fe, Cr, W)7C3 were investigated by first principles. Tungsten doping can improve the ductility and the indentation modulus of (Fe, Cr)7C3 carbides. The elastic anisotropy of M7C3 became weaker after tungsten doping. A new carbide (Fe3.27Cr2.99W0.74) C3 was found to be a combination of mechanical properties. Tungsten doping is critical for the wear resistance and application of High-Chromium Cast Iron (HCCI). A series of investigations of (Fe, Cr, W)7C3 carbides were performed by first principles calculations and experimental analysis. The calculated results showed that with the increase in tungsten content in M7C3, the equilibrium cell volumes and the density gradually increased, and the formation energy of M7C3 carbides gradually decreased. The TEM results showed that the (Fe, Cr, W)7C3 carbides were (Fe3.27Cr2.99W0.74) C3 with a hexagonal structure after adding 2.13 wt % tungsten into laser cladding coatings of High-Chromium Cast Iron with a composition of Fe-26.8 wt % Cr-3.62 wt % C. These results from calculations and in situ nanoindentation show that tungsten doping could improve the ductility and indentation modulus of (Fe, Cr)7C3 carbides, and the composition of (Fe, Cr, W)7C3 was expected to be a high hardness and softness material. The wear test results showed that the wear resistance of tungsten-bearing HCCI was better than ordinary HCCI. [ABSTRACT FROM AUTHOR]