Simulation And Experiment Study On 3D Printing Process Of Metal Powder

Metal 3D printing technology provides a new solution for the aerospace,bio-medical,national defense and other fields in manufacturing of complex structure.It has been promoted to an important strategy of a country.There are many technologies to realize metal 3D printing,but the intrinsic mechanism that is the interaction of high energy density laser beam or electron beam with metal powders is similar.The process of "area melting-powdering-area melting" has a significant impact on forming a part.Only depending on a large number of experiments to study the properties of the metal powders how to affect the 3D printing process,the cost will be high.Therefore,the computer simulation technology to aid to analyse the 3D printing process is needed.In this paper,Molecular Dynamics simulation is used to study the process of melting and cooling of Ti and Ti Al alloy under Selective Laser Melting and uniaxial tension simulation is used to study the influence of the properties of particle on the forming.Firstly,the two particle models are established to simulate the rapid melting of Ti and Ti Al alloy with uneven particles and different size particles under the laser beam heating.By analyzing the change of the crystal structure and the radial distribution function of the model during melting and calculating the comparison between the particle melting process of heat supply and demand to study the uneven and different size of particles how to affect the melting process.It is found that the uneven and size of the particles will affect the melting time.The melting time increases with the particle size,and the extra time will produce excessive heat.It will cause local temperature increasing.Then,the multi-particle models are established to simulate the uniaxial tension of the Ti and Ti Al alloy after rapid solidification with different particle gaps and particle sizes.By analyzing the change of density during the solidification and the change of potential energy in the process of tensile,it is found that the intrinsic factors of tensile strength are different because of potential energy.The bigger the potential energy is,the bigger the tensile strength is,but there is no obvious regularity in the change of particle gaps and sizes with tensile strength.The final density of models with different particle gaps are notmuch different.The particle sizes affect the final density of models.The higher final density is,the higher tensile strength is.Finally,the common test methods for metal powders used in 3D printing are summarized by taking Al Si10 Mg as an example.The mechanical experiments are tested by printing samples of Al Si10 Mg and the feasibility of the metal powder 3D printing process simulated by Molecular Dynamics is analyzed.