Research On Numerical Simulation Method Of Laser Surfacing

Laser surfacing welding is a process that uses a high-power laser beam to melt a thin surface layer and overlay powder at a localized location on the substrate to weld a new material layer on the substrate.This method allows the substrate to guarantee high strength and high toughness while redesigning the macro and micro structure of the substrate surface,repairing the surface structure of the part and even improving the performance of the part,making the surface of the part with high temperature resistance,wear resistance,fatigue resistance,corrosion resistance and other characteristics.The excellent properties of laser surfacing technology and its revolutionary three-dimensional manufacturing capabilities have led to continuous and extensive research by many scholars in China and abroad.The evolution of the temperature field and microstructure during laser surfacing welding has a very important impact on the mechanical properties of the overlay layer,but it is difficult and expensive to observe the evolution of the transient temperature field and microstructure in real time by experimental means.Therefore,in this paper,the dynamic simulation of the transient temperature field of laser surfacing welding is carried out by numerical simulation method,and the influence of process parameters on the temperature field is investigated,the distribution of temperature field is predicted by surrogate model and the evolution of microstructure of the overlay layer is simulated by phase field model,the main studies in this paper are as follows.(1)According to the basic theory of heat transfer,the convective heat transfer coefficient,thermal property coefficient and thermal radiation coefficient of the material surface are taken into consideration,and a three-dimensional finite element model of the transient temperature field of laser surfacing welding is established by using a double ellipsoidal heat source model and applying ABAQUS finite element software,which verifies that the"activation"technique of the unit It is verified that the deposition process of laser surfacing can be well simulated by the cell"activation"technique.The simulation of the temperature field in the laser surfacing welding process is carried out,and the distribution of temperature and temperature gradient in the overlay layer is obtained.The research plan of the influence of process parameters on the temperature field is designed,and the connection between the process parameters and the temperature field distribution is established,and the variation of laser power,laser scanning speed and the shape and size of the moving heat source on the temperature field distribution and the influence on the mechanical properties of the overlay layer are discussed.(2)An agent model-based prediction model of the temperature field of laser surfacing welding is established.The sample points are extracted by the optimal Latin hypercube sampling algorithm,the singular value decomposition is applied to reduce the dimensionality of the temperature field data,and the Kriging surrogate model is constructed in the low-dimensional response.and the temperature field distribution of laser surfacing welding is predicted through the surrogate model.The accuracy of the model was verified using the cross-validation criterion and the~2 test.Compared with the finite element model,the computational efficiency of the prediction model is significantly improved.(3)The temperature-dependent grain structure evolution model based on the phase field model was established by coupling the laser surfacing macroscopic temperature field model and the phase field model,and the growth process of the two-dimensional sectional grain structure of the laser surfacing formed overlay layer was predicted.