Structure simulation in unidirectionally solidified turbine blade by dendrite envelope tracking model(I): numerical modeling
(1.School of Materials Science and Engineering, State Key Laboratory of Materials Modification by Laser,
Ion and Electron Beams, Dalian University of Technology, Dalian 116024, China;
2. Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan;
3. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Ion and Electron Beams, Dalian University of Technology, Dalian 116024, China;
2. Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan;
3. School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
Abstract: A 3D dendrite envelope tracking model was developed for estimating the solidification structure of unidirectionally solidified turbine blade. The normal vector of dendrite envelope was estimated by the gradient of dendrite volume fraction, and growth velocity of the dendrite envelope (dendrite tips) was calculated with considering the anisotropy of grain growth. The solute redistribution at dendrite envelope was calculated by introducing an effective solute partition coefficient(ke). Simulation results show that the solute-build-up due to the rejection at envelope affects grain competition and consequently the solidification structure. The lower value of ke leads to more waved dendrite growth front and higher solute rejection. The model was applied to predict the structure of turbine-blade-shape samples showing good ability to reproduce the columnar and single grain structures.
Key words: turbine blade; dendrite envelope tracking model; structure simulation; unidirectional solidification