Research Progress in Numerical Simulation of Laser Cladding Process and Crack Regulation
Laser cladding is a three-way dynamic laser-powder-substrate interaction process in which the complex heat and mass transfer and convective behavior of the molten pool are closely related to the coating quality.Presently,it is difficult to visually and accurately observe the effect of the transient evolution of the laser cladding process on the coating quality by relying only on experimental methods,and it is limited by the high requirements of specialized equipment,high experimental costs,long cycle time,and other problems,which make it difficult to track the dynamic changes of multi-physical fields in the laser cladding process in real time.With the remarkable development of computer technology,numerical simulation provides an effective method for the in-depth analysis of the temperature change law,residual stress distribution,and melt pool flow behavior in the cladding process and provides a theoretical basis for process optimization and improvement of the coating quality.However,only a few reviews have addressed this aspect.Based on this,this paper reviews the current research status of the numerical simulation of multi-physical fields of the"temperature field-stress field-flow field"from the heat source models,thermal properties of materials,mechanical models and thermal-force coupling methods,as well as the flow behavior of the molten pool.The temperature and flow field evolution affect heat transfer,convection,and solidification in the molten pool,which directly affects the coating quality.Owing to the strong transient nature of laser cladding,stress is easily generated inside the coating,which affects its morphology,dimensions,and performance.However,current research on the numerical simulation of the laser cladding process is still limited in the accurate reflection of the actual cladding situation.In the future,it will be necessary to comprehensively consider the details of multiple physicochemical changes in the laser cladding process,such as phase transition,heat conduction,and heat convection,and build more reliable and accurate models to predict the properties of the cladding layer by considering heat source models and boundary conditions that are more compatible with laser cladding and by reducing model simplification.For the crack regulation problem,the influencing factors causing cracks are summarized.Cracks are mainly caused by residual stress exceeding the tensile strength of the material,while differences in the material properties,dilution rate,and elemental segregation also have an impact.The intrinsic correlation between multi-physics field-coupled dynamic evolution,process optimization,and crack regulation is also outlined.Numerous influencing factors lead to crack generation,and accurate simulation results are necessary to effectively guide practice.Therefore,the difficulties affecting the accuracy of the simulation are summarized,and an outlook is provided.In the future,we can improve the simulation methods,optimize the process and material systems,and combine them with nondestructive testing technology.Comprehensive simulation,experiments,monitoring,and other measures are used to establish a systematic and comprehensive crack quantitative index.Starting from the dynamic evolution level of multiscale multi-physical field coupling,realizing the integrated regulation of cracks will be the focus of future research.With continuous development and improvement at the industrial level,the realization of industrial intelligence and automation is an inevitable trend for future development,and the use of numerical simulation technology to guide the actual laser cladding process is a reliable method for effectively improving the coating quality.Therefore,a systematic review of the intrinsic connection between the dynamic evolution of multi-physics fields in laser cladding and crack regulation is necessary to provide references for subsequent research or practical work on numerical simulation and crack regulation of the laser cladding process.
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