Microstructure and wear properties of Fe–6wt.%Cr–0.55wt.%C–Xwt.%Nb laser cladding coating and the mechanism analysis

Abstract

Ultra-high performance FeCrC laser cladding coatings with different Nb contents were designed. The effect of Nb content on the microstructure and properties of the coating was researched and the corresponding influence mechanism was analyzed. The microstructure of the coating consists of martensite matrix and MC carbide. With Nb content increases form 0wt.% to 0.71wt.%, the martensite matrix is refined and the amount of MC carbide is increased, so the hardness, strength and wear resistance of the coating improve gradually. When the Nb content is 0.71wt.%, all of the properties are the excellent, in which, the hardness is 620HV, the tensile strength and yield strength are 1588MPa and 1344MPa, respectively, the abrasive wear weight loss is 0.15g/h and the COF of adhesive wear is 0.52. The lattice misfit between (110)NbC//(100)α-Fe is 10.3%, which indicates that NbC act as the heterogeneous nucleus of α-Fe is medium effective. With the increase of the Nb content, the precipitation temperature and precipitation amount of MC carbide both increase, when the Nb content is 1.03wt.%, they are 1072°C and 0.97wt.%, respectively.