Study on microstructure and compressive properties of Fe-C-W-Cr-V-Nb coating with boron addition

Abstract

A trace amount of boron was added into Fe-based coatings prepared on 42CrMo by laser cladding. The effect of additive boron level on the reinforcements and compressive properties of the coating were analyzed; the microstructure evolution and strengthening mechanism of the coating were illustrated by first-principle calculation. When the additive boron level changed in the coating, the reinforcements transformed from NbC type carbide to Cr23C6 type carbide and finally to Fe3C type carbide, and the strength of the coatings improved significantly. When the boron content was raised to 0.75%, the coating exhibited the best compressive strength and plasticity (3510 MPa with 6.39% strain). The compression properties of the coating defined a new space in the strength-ductility map. The addition of boron was beneficial to forming a eutectic structure composed of Fe3C type carbides and γ-Fe by reducing the formation energy of Fe3C. The Fe3C type carbide played an important role in increasing the strength, and the γ-Fe around Fe3C type carbide could improve the plasticity of the coating.