Electron beam additive manufacturing is an effective method for the fabrication of complex metallic components.With rapid solidification,the characteristics of microsegregation within the interdendritic region are int...Electron beam additive manufacturing is an effective method for the fabrication of complex metallic components.With rapid solidification,the characteristics of microsegregation within the interdendritic region are interesting and important for the subsequent phase transformation and final mechanical properties.However,in view of the microsecond lifetime and the small length scale of the molten pool,experimentally investigating microsegregation is challenging,even with electron probe micro-analysis.In this study,a multiphase-field model coupled with the real thermodynamic data of Ti6Al4V alloy was successfully developed and applied to simulate the rapid solidification of columnarβgrains via electron beam additive manufacturing.The thermal gradient(G)and cooling rate(R)were obtained from a 3D powder-scale multiphysics simulation and provided as inputs to a multiphase-field model.The eff ects of the electron beam process parameters and thermal conditions on the columnarβgrains were investigated.Liquid films and droplets were observed to have solute enrichment in the intercellular region.The size of the liquid film increased at a lower scanning speed and energy power.Increasing the scanning speed and energy power refined the columnarβgrains and decreased the liquid film size.The extent of microsegregation considerably increased at lower energy power,whereas the change in scanning speed had little eff ect on the microsegregation.The results also indicate that solute vanadium results in significant solute trapping and microsegregation during the rapid solidification of the Ti6Al4V alloy.展开更多
基金the National Key Research and Development Program of China(Grant No.2017YFB1103303)the National Natural Science Foundation of China(Grants No.51874245)+1 种基金the Fundamental Research Funds for the Central Universities(No.3102019ZD0402)the Research Fund of the State Key Laboratory of Solidification Processing(Northwestern Polytechnical University),China(Grant No.2020-TS-06)。
文摘Electron beam additive manufacturing is an effective method for the fabrication of complex metallic components.With rapid solidification,the characteristics of microsegregation within the interdendritic region are interesting and important for the subsequent phase transformation and final mechanical properties.However,in view of the microsecond lifetime and the small length scale of the molten pool,experimentally investigating microsegregation is challenging,even with electron probe micro-analysis.In this study,a multiphase-field model coupled with the real thermodynamic data of Ti6Al4V alloy was successfully developed and applied to simulate the rapid solidification of columnarβgrains via electron beam additive manufacturing.The thermal gradient(G)and cooling rate(R)were obtained from a 3D powder-scale multiphysics simulation and provided as inputs to a multiphase-field model.The eff ects of the electron beam process parameters and thermal conditions on the columnarβgrains were investigated.Liquid films and droplets were observed to have solute enrichment in the intercellular region.The size of the liquid film increased at a lower scanning speed and energy power.Increasing the scanning speed and energy power refined the columnarβgrains and decreased the liquid film size.The extent of microsegregation considerably increased at lower energy power,whereas the change in scanning speed had little eff ect on the microsegregation.The results also indicate that solute vanadium results in significant solute trapping and microsegregation during the rapid solidification of the Ti6Al4V alloy.
