Study On Microstructure Refinement And Properties Of TiC-VC Reinforced Fe-based Laser Cladding Layers

Iron and steel material is an indispensable metal material in the process of industrialization,which is widely used in all fields of social production and life.However,due to the huge waste of resources caused by material failure,surface engineering can improve the surface properties of metal materials,reduce the waste of resources and improve the level of green production.As a new surface strengthening and repairing technology,laser cladding can significantly improve the wear resistance,corrosion resistance and oxidation resistance of the substrate surface.It can not only meet the specific requirements for the surface properties of the materials,but also save a large number of valuable alloy elements.In this paper,The microstructure refinement and properties of TiC-VC reinforced Fe-based laser cladding layersare studied.Cladding experiment with Fe-Ti-V-C alloy powder.The effects of pulse laser processing parameters?pulse frequency and duty cycle?and the particle size of alloy powder on the microstructure and properties of Fe based coating were studied.It is found that the particle size of TiC-VC decreases and the hardness of the coating increases with the increase of duty cycle from 65%to 95%.With the increase of pulse frequency from 5 Hz to 5000 Hz,TiC-VC,the particle size increases at first and then decreases,and the hardness and corrosion resistance decrease at first and then increase.When the pulse frequency is 5 Hz,the coating property is better.With the increase of laser coating scanning speed,the heat input decreases and the melting width decreases.In a certain range,the particle size of TiC-VC decreases at first and then increases with the increase of scanning speed,and the hardness of the coating increases at first and then decreases.The study on the influence of the particle size of the alloy powder on the size and the properties of the Fe-based cladding.The results show that the average size of TiC-VC particles in the coating decreases with the decrease of the initial alloy powder size.The microstructure of the coating is transformed from lath martensite to flake martensite and retained Austenite.The hardness and corrosion resistance of the coating prepared by 75?m-150?m alloy powder are better.When the particle size of the graphite is reduced alone,the in-situ self-generated TiC-VC particle size decreases.When the particle size of the graphite is reduced to the nanometer size,the carbide is coarsened and accumulated,and the microstructure of the cladding layer is converted into a ferrite and a pearlite structure,and the performance of the cladding layer is relatively poor.After the particle size optimization of the initial alloy powder,the in-situ autogenerated carbide in the coating layer is changed from TiC,C0.88V to submicron/nanocomposite carbide TiVC₂,and the corrosion resistance of the initial coating becomes better.Based on the gradient particle size alloy powder and the cooperative control of pulse laser coating process,the submicron Ti-V carbide enhanced ultra-fine grain Fe base coating was obtained.the coating was formed well,the hardness of the coating increased and the corrosion resistance of the coating was greatly improved.