Phase-field simulation of microstructure evolution in electron beam additive manufacturing
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THE EUROPEAN PHYSICAL JOURNAL E
Regular Article
Phase-field simulation of microstructure evolution in electron beam additive manufacturing Shuo Chu1 , Chunwen Guo1 , Tongxin Zhang1 , Yueting Wang1 , Junjie Li1,a , Zhijun Wang1,b , Jincheng Wang1 , Ya Qian2 , and Haiyan Zhao2 1 2
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, P.R. China Department of mechanical engineering, Tsinghua University, Beijing, 100084, P.R. China Received 31 December 2019 and Received in final form 21 April 2020 Published online: 10 June 2020 c EDP Sciences / Societ` a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. Electron beam additive manufacturing (EBAM) is an emerging additive manufacturing technology with extremely high energy beam. The rapid solidification in the molten pool is of interest but not fully understood. In EBAM, with both large thermal gradient and cooling rate, the microstructure evolution during solidification is difficult to be described. The quantitative multi-phase-field model provides an effective way to reveal the dynamic evolution of dendrites in the molten pool of EBAM. In this study, the thermal profile is interpolated from the macroscale simulation at each time-step, to couple the realistic thermal evolution in the molten pool. The microstructure evolution and competitive growth have been investigated in details. Simulations of dendrite arrays with the same orientation showed how the growth velocity and the primary spacing of columnar dendrites depend on thermal gradient and cooling rate. The results are in agreement with theoretical models qualitatively. Moreover, the Gaussian nucleation model was introduced so as to give a better prediction of the microstructure in EBAM.
1 Introduction EBAM is an emerging additive manufacturing (AM) technology, where a high-energy electron beam is used as a powerful heat source to melt the metallic powders and fuse according to a predetermined processing path, stacking layer-by-layer, and finally forming metallic parts in a short time with high precision [1]. EBAM has broad industrial prospects in aerospace and bioengineering industry [2]. During the EBAM process, an instantaneous molten pool is formed when the electron beam scans the surface at a high speed. The heat flow is rapidly absorbed by the substrate material, resulting in a moving thermal field on the surface and rapid solidification. There are many complex physical processes [3] along with the rapid solidification in the molten pool, including thermal/mass transport, and fluid flow of the solidification [4–6]. The solidification can be controlled by changing the nucleation and growth of grains to determine the final microstructure. Therefore, an in-depth investigation of the microstructure
Contribution to the Topical Issue “Branching Dynamics at the Mesoscopic Scale” edited by Yongsheng Han, Hui Xing, Dongke Sun. a e-mail: [email protected] (corresponding author) b e-mail: [email protected] (corresponding author)
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