Microstructure and property of laser clad Fe-based composite layer containing Nb and B4C powders

Abstract

In present study, Fe-based composite layers were fabricated on steel substrate by laser cladding with or without the addition of Nb and B4C in Fe-based alloy powders. The phase composition, microstructure evolution, microhardness and wear properties of Fe-based composite layers were studied. The results showed that the phases in the Fe-based composite layer were mainly α-Fe, Fe2B, Cr7C3 and Cr23C6. The addition of Nb and B4C resulted in the in-situ formation of NbC phase, an increase in the amount of Fe2B phase, and the refinement of the microstructure in the Fe-based composite layer. The microhardness of the Fe-based composite layer was increased by 269.5 HV0.5 and the wear resistance was improved to about 1.5 times the original wear resistance when the 5% Nb and 5% B4C powders were added. The wear mechanisms of both two Fe-based composite layers were abrasive wear and adhesive wear.