Numerical Simulation on Temperature Field and Flow Field of Molten Pool in Laser Cladding

The stress of laser cladding molten pool, including surface tension, viscous shear, gravity and shielding gas pressure, was briefly expounded, and the formation mechanism of cladding layer was briefly analyzed from the aspects of tissue growth and molten pool flow. Moreover, a reasonable heat source model was established to obtain accurate numerical simulation results. The energy distribution laws and equations of different heat source models used in laser cladding simulation were summarized, including surface Gaussian heat source, surface annular heat source, Gaussian body heat source, ellipsoid heat source, compound heat source, etc. Based on the depth analysis of their characteristics, the research progress of numerical simulation of temperature and flow fields of laser cladding pool in China and abroad in recent years was summarized respectively. In addition, the advantages, disadvantages and application scope of various heat source models were analyzed and the distribution laws of temperature field and flow field obtained by different heat sources were discussed, providing a reference for the selection of heat source models. Furthermore, the free surface of the molten pool directly determined the size profile of the cladding layer and the research methods of free surface of molten pool were summarized, including Level Set, Volume of Fluid, Coupled Level-Set with VOF, Phase Field, Arbitrary Lagrangian-Eulerian, etc. By reviewing the research progress of free surface tracking, the advantages and disadvantages of various methods were clarified. Then, while establishing a reasonable numerical analysis model, it was also necessary to verify the model, so the verification methods of flow and temperature fields were described in detail, including measurement and non-contact measurement, as well as in-situ detection and non-in-situ detection. At the same time, numerical simulation technology is mature and simulation of temperature field and flow field of laser cladding is beneficial to revealing metallurgical dynamics of molten pool, but there are still some deficiencies in the molten pool simulation. The problems existing in the numerical simulation of laser cladding pool are pointed out from the aspects of numerical model and boundary conditions, and a number of targeted responses and solutions are raised. Finally, based on the developing status of the simulation research, its future development direction is prospected: one of the future development trends of numerical simulation in laser cladding pool will be the free-form surface, and will give a scientific explanation of the flow behavior and morphology changes of the molten pool under non-planar condition. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.