Distribution Characteristics and Reinforcing Behavior of (Ti, Nb)C Reinforced Particle in the Coating Fabricated by Laser Rapid Cladding

(Ti, Nb)C reinforced Fe-based laser coatings were prepared with normal and high scanning velocities of the laser beam. The distribution characteristics of reinforced particles in the coatings were investigated. The mechanical properties of coatings were tested. The results showed that the morphologies of the microstructure and the reinforced particle changed dramatically at high solidification rate due to rapid laser processing compared with that prepared by normal processing. Two kinds of particles were observed in the coating. One was (Ti, Nb)C multiple carbide particle with the size of micron and sub-micron scales, in which a mass of dislocations were found. Another was nano-sized particle including α-Fe and (Ti, Nb) C obtained by rapid solidification. The microstructure of the coatings was highly refined and a large number of twin crystals were found in matrix. The results of mechanical properties test revealed that the wear resistance of the coating was improved by rapid laser processing, compared with that of the coating prepared with normal speeds. The above-mentioned conclusion indicated that rapid laser cladding can promote not only the processing efficiency but also the mechanical properties of the coating.