Journal ArticleDOI
Thermal and Grain Structure Simulation in a Land-based Turbine Blade Directionally Solidified with the Liquid Metal Cooling Process
TLDR
In this article, the thermal field and the grain structure of a cored superalloy turbine blade, which has been directionally solidified with the liquid metal cooling (LMC) process, has been simulated in three dimensions using a cellular automaton coupled with finite-element (CAFE) model.Abstract:
The thermal field and the grain structure of a cored superalloy turbine blade, which has been directionally solidified with the liquid metal cooling (LMC) process, has been simulated in three dimensions using a cellular automaton (CA) coupled with finite-element (CAFE) model. The cooling induced by the liquid aluminum bath has been replaced by a heat-transfer coefficient, whose temperature- and time-dependence has been adjusted on the basis of natural convection simulations and dimensionless analyses. The simulated grain structure and crystallographic texture have been compared with the microstructure, and the electron back-scattered diffraction (EBSD) results were obtained for a real blade. In both the experiment and the simulation, it has been found that the grains do not exhibit a well-defined texture, even near the top of the blade, mainly as a result of a concave liquidus surface. In order to improve the texture and decrease the number of stray crystals, the LMC process was then optimized by changing several parameters. The baffle geometry, the liquid bath level, and the thermal conductivity of the ceramic mold were found to be the dominant parameters. Using the optimized design, the effect of the withdrawal rate on the resulting grain structure was investigated.read more
Citations
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Journal ArticleDOI
Directional solidification of large superalloy castings with radiation and liquid-metal cooling: A comparative assessment
Andrew John Elliott,Tresa M. Pollock,Sammy Tin,W. T. King,S. C. Huang,Michael Francis Xavier Gigliotti +5 more
TL;DR: A columnar-grain variant of single-crystal RENE N4 has been directionally solidified over a range of conditions in order to assess the possible benefits of the use of liquid metal-enhanced cooling for large cross-sectional castings as discussed by the authors.
Journal ArticleDOI
Application of electron backscatter diffraction to the study of phase transformations
TL;DR: The application of the electron backscatter diffraction technique to the investigation of phase transformations is reviewed in this article, where a wide variety of results obtained using this technique are illustrated and discussed, focusing on thermodynamics and kinetics of phase transformation, solidification, solid state phase transformations, environmentally assisted reactions and thin film deposition.
Journal ArticleDOI
Thermal Analysis of the Bridgman and Liquid-Metal-Cooled Directional Solidification Investment Casting Processes
TL;DR: In this article, models of the directional solidification processes for columnar-grain alloy GTD-444 are used to evaluate the various heat transfer steps and heat extraction modes within each process.
Journal ArticleDOI
A new microsegregation model for rapid solidification multicomponent alloys and its application to single-crystal nickel-base superalloys of laser rapid directional solidification
TL;DR: In this paper, a new micro-segregation model for rapid solidification multicomponent alloys was developed to predict the microsegregation in the single-crystal superalloys of laser rapid directional solidification.
Journal ArticleDOI
Mechanical Blocking Mechanism for the Columnar to Equiaxed Transition
TL;DR: In this article, the columnar front during columnar to equiaxed transition (CET) is studied by quantitatively comparing the CET positions obtained with one stochastic model and two deterministic models for the unidirectional solidification of an Al-7 (wt pct) Si alloy.
References
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Book ChapterDOI
Theory of Microstructural Development during Rapid Solidification
Rohit Trivedi,Wilfried Kurz +1 more
TL;DR: In this article, some of the fundamental factors which play important roles in determining microstructures under rapid solidification condition are described, and it is shown that the interface stability analysis needs to be extended to include the possibility of high thermal as well as high solute undercoolings.
Journal ArticleDOI
A 3D Cellular Automaton algorithm for the prediction of dendritic grain growth
Ch.-A. Gandin,Michel Rappaz +1 more
TL;DR: In this paper, two-and three-dimensional (3D) cellular automata (CA) algorithms are proposed for modeling the growth of dendritic grains from the liquid phase.
Journal ArticleDOI
Analysis of solidification microstructures in Fe-Ni-Cr single-crystal welds
TL;DR: In this paper, a general procedure for predicting the solidification microstructure of single-crystal welds with any arbitrary orientation is established, and steady state is established within a few millimeters of the beginning of the weld.
Journal ArticleDOI
Prediction of Grain Structures in Various Solidification Processes
TL;DR: In this article, a physically based cellular automaton (CA) model was coupled with finite element (FE) heat flow computations and implemented into the code3-MOS. This CAFE model, which allows the prediction and visualization of grain structures during and after solidification, is applied to various solidification processes: the investment casting of turbine blades, the continuous casting of rods, and the laser remelting or welding of plates.
Journal ArticleDOI
Influence des conditions de solidification sur le déroulement de la solidification des aciers inoxydables austénitiques
TL;DR: In this paper, the effects of the composition and rate of solidification on mode (δ or γ) o austenitic stainless steels are studied on the bases of former experimental results and of a theoretical analysis of constrained dendrite growth.
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