Microstructure and mechanical properties of in situ(Ti,Nb)C_p/Fe-based laser composite coating prepared with different heat inputs

摘要

In this paper, in situ (Ti, Nb)C particle ((Ti,Nb)C_p) reinforced Fe-based composite coatings were produced by laser cladding on the surface of the high carbon steel. The effects of heat input on the microstructure, distribution characteristics of particle, and mechanical properties of the coating were investigated. The results show that (Ti, Nb)C multiple carbide particle is synthesized during solidification of molten pool. The size of particle coarsens gradually, the area ratio of particle increases, and the amount of particles presents a non-monotonous variation with the increase in energy density. The mechanical properties of the coating are improved dramatically compared with those of the substrate, benefiting from its higher hardness and dispersed in situ (Ti, Nb)C_p in it. With the change in heat input, the mechanical performances of the coating vary except the hardness. When energy density is1×10～5 J·mm～(-2), tensile strength and wear resistance of the coating achieve optimal value due to moderate content and size of the particle in the coating.