Research On Composite Strengthening Mechanism And Properties Of Inconel 625 Alloy Based On Laser Melting Deposition

Inconel 625 superalloy has excellent properties and is widely used in aerospace,industrial and chemical fields,etc.In order to further improve its wear resistance,the idea of preparing tungsten carbide and graphene reinforced Inconel 625 composite material by laser melting deposition method is proposed.Inconel 625/WC-12Co composite coating and Inconel 625/graphene composite coating are prepared.The microstructures and properties of coatings were studied by field emission scanning electron microscope(FESEM),x-ray diffractometer(XRD),Raman spectrometer,microhardness tester and friction and wear tester.The main work's contents and results are as follows:(1)Single track experiments of Inconel 625 alloy were carried out on Q235substrate by changing the laser power and scanning speed.Choose appropriate aspect ratio and dilution rate,the optimum process parameters are obtained:laser power 750W,scanning speed 8.5mm/s,and overlap ratio 50%.(2)Composite coatings containing 0wt%,5wt%,10wt%and 15wt%WC-12Co were prepared.The microstructure,microhardness and friction and wear properties of Inconel 625 coating and composite coatings were analyzed.Inconel 625 coating is mainly columnar crystal,equiaxed crystal and cellular crystal,and the phase composition is mainly?-Ni matrix phase.Spherical WC-12Co particles are uniformly distributed in the coatings,some of them are ablated and decomposed,and element segregation occurs between interdendrite,resulting in Nb C,M₂₃C₆ and other new phases.Adhesion wear is the main mode of Inconel 625 coating.With the increase of WC-12Co ratio,the wear resistance of particle reinforced composite coating is further enhanced,and the microhardness increases from 264HV_0.2 to 308HV_0.2.(3)The mixed powder with 5wt%graphene content was prepared by ball milling method,and the LMD experiment was carried out with the mode of prefabricated powder.The graphene composite coating is dominated by reticular dendrites,with obvious channel segregation,and a large number of star-shaped or point-shaped precipitates.Raman spectra shows that graphene still exists in the composite coating,but the defect density increases.The microhardness of graphene composite coating is increased by 376.9HV_0.2 compared to without graphene,the adhesion wear degree is greatly reduced,the oxidation wear is dominant,and the friction and wear properties are improved significantly.