Simulation Analysis Of Temperature Field And Stress Field Of Laser Cladding CoNiCrAlY

The thermal barrier coating consists of a ceramic coating with thermal insulation and a bonding metal bonding layer,wherein the metal bonding layer is MCrAlY(M=Ni,Co or Ni-Co)to improve the ceramic coating.The physical compatibility of the substrate,the quality of the bonding layer is one of the main factors determining the service life of the thermal barrier coating.Laser cladding technology,as an emerging technology for preparing metal bonding layers,uses a high-energy laser beam to form a metallurgically bonded metal bonding layer on the surface of the substrate by powder feeding or powdering.Under the current technology,it is very difficult to obtain the distribution of the internal temperature field and the stress field in the laser cladding process through experiments.Based on the finite element numerical simulation method,not only the temperature field and stress field in the laser cladding process can be simulated,but also a convenient way for the selection and even optimization of the laser cladding process parameters.The main work of the thesis is as follows:Firstly,the laser cladding CoNiCrAlY finite element model is established by setting the thermal property parameters of the material in ANSYS.By applying the heat source to the model,the size and temperature information of the molten pool under 1400 W,1600W and 1800 W laser power are obtained.According to the process parameters selected by the model,the corresponding laser cladding experiments were carried out.The experimental results obtained a good cladding layer combined with the matrix under the three laser powers,which is consistent with the simulation results.In the geometry of the molten pool,the experimental results in the depth direction are consistent with the simulation results.In the width direction,the simulation results are compared.The experimental results are slightly wider.Comprehensive comparison of simulation results and experimental results proves that the established finite element model is feasible.Secondly,a simulation of the multilayer temperature field was performed.By applying different process parameters(laser power,scanning speed)to the model,the variation of the size,temperature and cooling rate of the molten pool with the process parameters in the process of laser cladding multi-layer CoNiCrAlY is obtained.The influencing factors of the final cladding quality.At the same time,the experimental platform of molten pool temperature monitoring was built to monitor the variation of temperature field during laser cladding,and the results of finite element simulation were verified by experiments.Finally,the temperature field simulation results are applied as temperature load to the model after the conversion unit type,and the boundary conditions are applied to the model to obtain the residual stress inside the model under different process parameters,which provides a reference for the optimization of process parameters.