Finite Element Analysis Of Ti-6Al-4V Titanium Alloy Fabricated By Additive Manufacturing Via Electron Beam Melting

Electron beam additive manufacturing is one of advanced additive manufacturing technologies in recent years.It has been gradually applied in the fields of rapid manufacturing,biomedical engineering and so on.In the process of EBAM,the powder layers underwent rapid heating and cooling,which resulted in high temperature gradient and then generation of stress and strain fields.Residual stress and strain seriously affect the formability of materials,and reduce the dimensional accuracy and properties of the parts.Thus,it is important to study the temperature and stress fields in the forming process of EBAM for optimizing the processing technology and improving the mechanical properties of the parts.In this paper the temperature and stress fields of the bulk and porous cubic Ti-6Al-4V meshes were studied by large-scale finite element analysis software ANSYS.The distribution of temperature field in bulk materials is studied.The influence of different process parameters on temperature field and the distribution law of multi-layer and multi-channel temperature field are mainly analyzed.The results showed that process parameters have different effects on the temperature field.The molten pool temperature and cooling rate increases with the increase of scanning power,and the decrease of electron beam spot diameter,scanning spacing,scanning speed.With the increase of scanning power,the width of molten pool increases and the depth decreases.By controlling the electron power,the temperature of molten pool can be controlled to achieve smaller temperature gradient.Based on the results of temperature fields of bulk material,the temperature fields of the porous cubic meshes under the annular scanning path and the Y-direction scanning path were analyzed.The results showed that the substrate temperature,molten pool temperature,cooling rate and temperature gradient under the annular scanning path are higher than that under the Y-direction scanning path.By using the indirect thermo-mechanical coupling method,the stress field of porous cubic mesh materials were analyzed.With the movement of electron beam spot,the compressive stress and tensile stress alternatively change along the scanning direction,and finally tends to be balanced.For additive manufacturing of single-layer meshes,the stress distribution under the Y-direction scanning path is more uniform.For the multi-layer meshes,the non Mises stress under the annular scanning path is lower than that under the Y-direction scanning path.The maximum of the equivalent stress occurred at the central node and decreases with the increase of scanning layers.