Study On Laser Cladding Process Of In-situ WC Reinforced Nickel-based Coating And Its Database

H13 die steel is widely used in die-casting dies,forging dies and hot extrusion dies with large impact loads.The mould is prone to failure modes such as wear,cracks and fractures under the action of large loads.Laser cladding is an advanced surface strengthening technology that can increase the service life of the mold.In-situ generated particle-reinforced cladding layer has the characteristics of thermodynamic stability,clean particle and matrix interface,high particle bonding strength and simple synthesis process.In this thesis,based on laser cladding technology,in-situ generated WC-reinforced Ni-based coating is prepared on the surface of H13 mold steel,which improves the hardness and wear resistance of the mold steel and extends the service life of the mold.The specific research contents are as follows:(1)Finite element analysis of laser cladding Ni-based coatingThe thermophysical parameters of Ni60 and(W+C)mixed powder were calculated by using JMat Pro material analysis software.Based on the simulation software COMSOL,the temperature field and thermal stress field of the in-situ generated WC-reinforced Ni coating were simulated and analyzed by using a continuous plane heat source,and the ideal laser process parameters are obtained.Through the analysis of the thermal stress cycle of the cladding layer,the maximum thermal stress and residual stress value in the coating are obtained;the alternating thermal stress in the cladding coating is found,and the value of the maximum stress amplitude is obtained.By analyzing the thermal cycle and thermal stress cycle of the cladding layer,the depth of the cladding layer is obtained.The laser cladding experiment is carried out according to the process parameters obtained from the simulation,and the accuracy of the simulation results is verified.(2)Preparation of in-situ WC-reinforced Ni-based coatingThrough the HSC software,the possible in-situ reactions in the cladding process are analyzed,and the feasibility of in-situ generation of WC is determined.The in-situ WC-reinforced Ni-based coating and the external WC-reinforced Ni-based coating are prepared.Comparative analysis is carried out in terms of coating morphology,particle morphology,coating hardness and wear resistance.The in-situ WC-reinforced Ni-based coating the performance of the layer is higher than that of the external WC reinforced Ni-based coating.The in-situ WC-reinforced Ni-based coatings with different process parameters and different powder ratios are prepared,and the influence of laser process parameters on the phase,microstructure and microhardness of the in-situ WC-reinforced Ni-based coatings is obtained.The friction and wear performance of in-situ generated WC-reinforced Ni-based coatings under different powder ratios were analyzed,and the mechanism of the in-situ generated WC-reinforced particles on the friction and wear properties of the cladding layer are revealed.(3)Establishment of laser cladding databaseThe database of laser cladding process is created by Visual Basic language and Access2003 on Windows platform.The database mainly contains two modules: data module can input laser cladding process parameters and cladding coating performance parameters,and can also inquire the cladding coating performance parameters through process parameters.The image module can store and query the coating phase diagram.