Research On Simulation Of Selective Laser Melting Of Metal Matrix Nanocomposites

As a metal Additive Manufacturing technology,selective laser melting(SLM)has been widely used in many fields by virtue of its characteristics of producing parts with high density and high dimensional accuracy.Nowadays,there are more researches on the SLM of metal matrix nanocomposites(MMNCs).In this paper,a simulation model of the SLM process of TiC reinforced Ti6A14V nanocomposites is established to study the influence of nano-reinforcement on molten pool dynamics.Firstly,based on the finite volume method(FVM)modeling theory,a three-dimensional transient model for a single-track SLM process is established with the consideration of the phase transition,nonlinearity of material properties,laser beam with Gaussian distribution,Marangoni convection.Compared with previous models,the impacts of nanoparticles on the variation of thermal physical parameters of nanocomposites,like viscosity,surface tension,laser absorptivity and thermal conductivity,are taken into consideration in our model.Then,based on the established FVM model,the influence of TiC content on the temperature field,velocity field and dimensions of molten pool is studied.The numerical simulation results show that with the increase of TiC volume fraction,the maximum temperature of the molten pool increases and the maximum flow velocity of the molten pool decreases.When the TiC volume fraction increases from 0%to 10%,the molten pool length and depth increases from 247.7 ?m and 35.3 ?m to 280.1?m and 43.4 ?m,respectively,and the molten pool width decreases from 225.4 ?m to 180.8?m.A new parameter,called remelting width,is defined.Remelting width increases with the increasing of TiC content,which helps to expand the processing windows for the SLM process.The significance of the change of thermophysical parameters caused by TiC content on the molten pool dynamics is explored.The results show that the weakening of Marangoni convection is the main factor affecting the temperature and velocity fields of molten pool.Finally,the effects of laser power,scanning speed and TiC content on the maximum temperature,maximum flow velocity and remelting width of the molten pool are quantitatively investigated by analysis of variance(ANOVA).On the basis of ANOVA,multivariate linear regression analysis is carried out,and the optimization strategy of the SLM process parameters for TiC/Ti6Al4V nanocomposites is given according to the fitting equation.