Microstructure and sliding wear properties of laser clad TiN reinforced composite coating

The microstructure and sliding wear properties of a laser clad TiN composite coating on steel 1045 hare been investigated using scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and energy dispersive X-ray analysis and a pin-ring dry sliding wear test machine. Excellent fusion bonding with low dilution and absence of cracks has been obtained under laser cladding conditions in which specific energy was in the range 5-20 kJ cm^-2 and power density was in the range 3·5-5 kWcm^-2. The clad layers have been characterised by metallurgical examination, which showed that the bonding zone, which is about 6 μm thick, is a γ nickel solid solution growing from the bottom of the malten pool with planar crystal morphology. Particles of TiN,. γ nickel, and a fine eutectic of γ nickel and (Fe,Cr)₂₃ C₆ in the interdendritic regions have been observed and a large number of TiN particles with irregular shapes remained after laser cladding. Partial dissolution occurred on the edges of the original TiN particulates, growth in which during resolidification was found in the clad region. The TiN reinforced composite coating produced by laser cladding has also been shown to possess good wear resistance.