A transient,two-dimensional,coupled finite element model was employed to simulate the solidification and shrinkage of continuous casting steels by means of ANSYSTM.In the model,a gap-dependent heat transfer condition was introduced to modify the heat flux function,and the variations of material thermal properties,mechanical properties as well as the yield function with temperature were considered.The solidification and shrinkage processes of four round billets and two square billets were simulated by indirect coupled method.Simulation results show that carbon content,pouring temperature,casting speed and shape of billets have distinct influence on the solidification shrinkage of billets.Ideal continuous parabolic tapers were designed and optimized according to the calculated shrinkage curves of billets.
Wang Tongmin Cai Shaowu Li Jun Xu Jingjing Chen Zongning Zhu Jing Cao Zhiqiang Li Tingju
The microstructure of Al-Ni alloy has a significant influence on its performance, while electromagnetic stirring is one of the most effective methods for control of solidification structure of Al alloy. To investigate the effect of electromagnetic stirring on the solidification of the ingot, the solidification of the Al-50Ni alloy in vacuum with electromagnetic stirring was described by numerical simulation in this paper; and a three dimensional mathematical model was established. The electromagnetic field was simulated by ANSYS software and the thermal-flow field was simulated by FLUENT software. The coupling between the electromagnetic field and the thermal-flow field was implemented by user-defined subroutines. It is found that the current intensity has significant influences on the fluid flow and the microstructure of the alloy. The simulation results agree well with the experimental results, and the optimum current intensity under the exprimental conditions is 80 A, while the frequency is 50 Hz.
This study was trying to observe the real-time dendrite growth of Sn-Bi and Sn-Pb binary alloys by a synchrotron radiation imaging technology.The imaging system includes an intense and high brightness synchrotron radiation source,a high-resolution and fast-readout charge coupled device camera,an alloy sample and a Bridgman solidification system.The imaging experiments were done at Beijing Synchrotron Radiation Facility with an updated synchrotron radiation imaging technique,diffraction-enhanced imaging,which was firstly used to study the dendrite growth of metallic alloy.A series of growth behavior and morphology evolution of dendrite have been in situ observed,such as columnar-to-equiaxed transition,dendrite competition,dendrite fragmentation and floating,etc.,which can offer the direct proofs to verify or improve the solidification theories of metallic alloy.This research opens a novel window for the study of alloy solidification and enables the unambiguous understanding of solidification processes in optically opaque,metallic alloys.
WANG TongMin1,XU JingJing1,LI Jun1,HUANG WanXia2,LIU ShengChu1 & LI TingJu1 1 School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China
