Finite Element Analysis Of Thermal Behavior Of Metal Powder During Selective Laser Melting Under Moving Heat Source

As the important branch of Rapid Prototyping and Manufacturing (PRM), selective laser melting (SLM) attracts more attentions due to its high quality and rapid manufacturing in terms of material with high melting point such as metal. However, there are still many defects including balling effect and deformation during SLM process because of the limitation of technology, and it is expensive and time-consuming to do experiment frequently to explore the theory of SLM. As a result, numerical simulation becomes more and more popular, which is useful to predict the effects of process parameters and material performance parameters on thermal behavior and molten pool dimensions during SLM process, and provide reliable theoretical support and reduce experiment cost.In this paper, aiming at TiAl6V4, the energy conservation equation with a moving Guassian energy source is developed, in which the non-linear temperature-dependent thermal physical properties of materials are taken into account, and material changes in different temperature range. By means of the finite element methods, the temperature distribution and molten pool dimensions are presented, and the related modeling and numerical methods are validated by previous experimental and numerical works. The effects of the linear energy density (LED), scanning track length, dense substrate, hatch spacing and time interval between two neighboring tracks on the temperature distribution and molten pool dimensions are obtained and analyzed. The temperature change of points in different location and the change of maximum temperature with time are explored. Besides, the comparison of whether or not considering volume shrinkage in simulation process is conducted. The results show that the increased laser power is superior to the reduced scan speed in thermal performance, which can improve the temperature distribution and molten pool dimensions. Shorter track, shorter hatch spacing can increase the temperature, and less time interval can lower the temperature gradient. Substrate can increase spread ability of molten pool and cool scanned area effectively, which is beneficial to next scanning. Although temperature field is not influenced by volume shrinkage, the average temperature and dimensions of the molten pool are affected, which is more close to the real situation.