| With the advancement of science and technology,the requirements for the use of molds have gradually become higher,and the problem of mold failure has become increasingly prominent.As a common surface modification method,laser cladding has the advantages of low dilution rate and metallurgical bonding between the cladding layer and the substrate.In this paper,TiC and Incone1718 are used as cladding materials,H13 is used as the substrate,and the laser cladding equipment with optical external coaxial powder feeding is used as the experimental equipment.The method of combining simulation and experiment is used to study the effect of process parameters on the temperature field and macroscopic of the cladding layer.The influence of morphology and other aspects.In addition,the microstructure and mechanical properties of cladding layers with different TiC content were studied.Finally,a choice that can improve the wear resistance of the hot extrusion die surface is reached.The main contents are summarized as following:(1)Simulation analysis of temperature field during laser cladding.The temperature field numerical model of laser cladding TiC particle-reinforced Inconel718 composite material was established using finite element software,and the influence of laser power,scanning speed and powder feeding rate on the temperature field,cladding layer morphology and solidification characteristics of the cladding process was explored.The final test and simulation results are in good agreement.With the increase of laser power and powder feeding rate,the maximum temperature,melting width and melting height of the cladding process increase.As the scanning speed increases,the maximum temperature,melting width and melting height of the cladding process decrease.(2)Research on the basic technology of laser cladding.Refer to the simulation results of the temperature field,firstly use the single factor method to explore the influence of the process parameters on the quality of the single-pass single-layer cladding layer(including the aspect ratio,dilution rate,and microhardness),and then use the response surface method to find a good quality process Parameter combination.A theoretical model of overlap rate and z-direction lift is proposed,and multiple layers of laser cladding are performed by changing the overlap rate and z-direction lift.Experiments show that the cladding layer is the flattest when the center distance is 1.57mm and the z-direction lift is 0.57mm.(3)Research on the microstructure of TiC/Inconel718 composite layer by laser cladding.According to the optimized process parameters,different content of TiC is added to laser cladding the composite material.When the TiC content is 5%,the reinforcement phase mainly exists in two forms:granular eutectic TiC and incompletely dissolved TiC.When the TiC content is 10%,in addition to a small part of eutectic TiC,the form of the reinforcement phase also appears dendritic primary TiC.When the TiC content reaches 15%,the dendritic primary TiC becomes coarse.There is a layer of carbides rich in Nb and Ti around the incompletely dissolved TiC.In terms of phase,with the increase of TiC content,the relative intensity of all diffraction peaks of TiC increases.Due to the existence of residual tensile stress,part of the TiC peaks shifted to a small angle.The preferred orientation changes part of the peak intensity of the ? phase.(4)Research on mechanical properties of laser cladding TiC/Inconel718 composite layer.The microhardness of the cladding layer with different composition is tested and analyzed.The addition of TiC helps to improve the microhardness of the cladding layer.When the TiC content is 5%,the friction coefficient is the smallest,and the wear scar width and depth are also the smallest.The wear volume of the matrix is about 13 times that of the sample when 5wt.%TiC is added.Whether it is the matrix or the cladding layer,the wear mechanism of the sample is mainly abrasive wear,adhesive wear and oxidative wear. |
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