Microstructures and properties of (2.4%+1.2Ti+15%WC)/FeCsiB layers produced by laser cladding

Abstract

Metal matrix composites (MMCs) layers reinforced by in situ carbide particles were formed by laser cladding using preplaced (2.4%Zr+1.2%Ti+15%WC)/FeCSiB alloy powders on a medium carbon steel matrix. The microstructures of cladded layers, composition and distribution of in situ particles in the cladded layers were observed with optical microscopy (NEOPHOT), scanning electron microscopy (OPTION CSM-950, KYKY2000) and metallographic microstructure computer analysis system. HX-200 micro-Vickers was used to examine the cladded layer microhardness. The microstructure characteristics of MMCs layers are typical hypoeutectic which y austenite dendrites distributed on the FeCSiB quaternary eutectic substrate. The energy dispersive spectroscopy (EDS) analysis shows the reinforcements are in situ synthesis carbides which compositions consist of main transition elements Zr, Ti, w and carbon. The compound carbide particles distributed within dendrite and interdendritic regions with 3.6— 5.8% volume fractions. The martensite transformation went with the rapid cooling processes also. The MMCs layers are dense and free of cracks with a good metallurgical bonding between the layer and matrix. The microhardness values across layer cross section vary between HV0.2 8OO—HV0.2 1000.