Microstructure and properties of Fe-base alloy +WC laser cladding layer

Laser cladding of Fe-base Alloy+WC powders on Q235 steel and QT-600 spheroidal graphite cast iron substrates was carried out.The microstructure,microhardness and wear resistance of the laser cladding layers were analyzed and tested with scanning electron microscopy(SEM),optical microscopy(OM),energy-dispersive spectrometer(EDS)and X-ray diffraction(XRD).The results show that the microstructure of the laser cladding layer on Q235 steel surface is fine,the interface between the coating and substrate is unconspicuous wavy and appears a bright layer.While the microstructure of the laser cladding layer on QT-600 spheroidal graphite cast iron surface is coarse.The wavy interface becomes more obvious and the interlarded amount of substrate is more.No bright layer appears.The hardness and wear resistance of the composite coating are relative lower.It is considered that the difference of the microstructure and properties is due to the higher melting point of Q235 steel which decreases the melted amount and the rapid cooling rate of laser molten pool which results in refined microstructure.The microstructure of the laser clading layer on QT-600 spheroidal graphite cast iron surface is un-uniform;equiaxed grains have higher wear resistance than that of columnar grains because equiaxed grains have more crystal boundary and enhance the resistance to slip.