Modelling of Grain Refinement in Aluminium Alloys

1999 ◽  
Vol 578 ◽  
Author(s):  
A. L. Greer ◽  
A. Tronche ◽  
M. Vandyoussefi
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Heat Flow ◽  
Temperature Gradient ◽  
Cellular Automaton ◽  
Directional Solidification ◽  
Grain Growth ◽  
Aluminium Alloys ◽  
Quantitative Prediction ◽  
Free Growth

AbstractCommercial grain refiners for aluminium solidification are so potent that the barrier forgrain initiation is that for free growth rather than for nucleation itself. In this case quantitative prediction of grain size is possible. For small melt volumes a successful isothermal-melt model is presented. This is extended to directional solidification in a temperature gradient using cellular-automaton modelling of grain growth with finite-element heat-flow calculations.

scholarly journals The ‘Isothermal’ Phase of Nova Dust Shells

1983 ◽  
Vol 72 ◽  
pp. 133-138
Author(s):  
R.M. Mitchel ◽  
A. Evans ◽  
M.F. Bode
Keyword(s):  
Grain Size ◽  
Temperature Gradient ◽  
Infrared Spectrum ◽  
Grain Growth ◽  
Optical Depth ◽  
Effective Temperature ◽  
Near Infrared ◽  
Dust Shell ◽  
Consistent Picture ◽  
Significant Temperature

AbstractWe describe a model for the evolution of the infrared spectrum of the dust shell of nova NQ Vul. The effects of nucleation and grain growth, together with.extended, but diminishing, mass loss from the nova, are included. The variations in the effective temperature of the dust shell that occur near infrared maximum may be understood in terms of varying optical depth in a dust shell having significant temperature gradient. However, a more consistent picture is shown to combine interrelated optical depth and grain size variations.

scholarly journals Prediction of Epitaxial Grain Growth in Single-Track Laser Melting of IN718 Using Integrated Finite Element and Cellular Automaton Approach

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5202
Author(s):  
Amir Reza Ansari Dezfoli ◽  
Yu-Lung Lo ◽  
M. Mohsin Raza
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Grain Growth ◽  
Heat Input ◽  
Single Track ◽  
Laser Melting ◽  
Melt Pool ◽  
Initial Substrate ◽  
Average Grain Size ◽  
Epitaxial Grain Growth

The mechanical properties of selective laser melting (SLM) components are fundamentally dependent on their microstructure. Accordingly, the present study proposes an integrated simulation framework consisting of a three-dimensional (3D) finite element model and a cellular automaton model for predicting the epitaxial grain growth mode in the single-track SLM processing of IN718. The laser beam scattering effect, melt surface evolution, powder volume shrinkage, bulk heterogeneous nucleation, epitaxial growth, and initial microstructure of the substrate are considered. The simulation results show that during single-track SLM processing, coarse epitaxial grains are formed at the melt–substrate interface, while fine grains grow at the melt–powder interface with a density determined by the intensity of the heat input. During the solidification stage, the epitaxial grains and bulk nucleated grains grow toward the top surface of the melt pool along the temperature gradient vectors. The rate of the epitaxial grain growth varies as a function of the orientation and size of the partially melted grains at the melt–substrate boundary, the melt pool size, and the temperature gradient. This is observed that by increasing heat input from 250 J/m to 500 J/m, the average grain size increases by ~20%. In addition, the average grain size reduces by 17% when the initial substrate grain size decreases by 50%. In general, the results show that the microstructure of the processed IN718 alloy can be controlled by adjusting the heat input, preheating conditions, and initial substrate grain size.

Finite Element Analysis on Directional Solidification of Al-Ni-Co Alloys

2012 ◽  
Vol 472-475 ◽  
pp. 494-498
Author(s):  
Shi Long Tian ◽  
Zhi Li Yang
Keyword(s):  
Finite Element ◽  
Temperature Gradient ◽  
Directional Solidification ◽  
Molten Steel ◽  
Solidification Front ◽  
Solidification Rate ◽  
Temperature Fields ◽  
Transient Temperature ◽  
Element Analysis ◽  
Co Alloys

Transient temperature fields of directional solidification of Al-Ni-Co alloys were studied by employing finite element method. Temperature gradient at solidification front and solidification rate was analyzed under different pouring temperature of molten steel. The results show that with different initial pouring temperatures of molten steel, individual ratio of temperature gradient at solidification front to solidification rate soars up in the initial stage of solidification, then varies within 2000-6000°C•s•cm-2, and finally plunges down and goes together when the solidification thickness reaches 5-6cm. Simulation result is consistent with the production reality. Numerical simulation results can provide an available reference for process optimization of directional solidification of Al-Ni-Co alloys.

Mean Field and Finite Element Modeling of Static and Dynamic Recrystallization

2012 ◽  
Vol 715-716 ◽  
pp. 737-737
Author(s):  
Roland E. Logé ◽  
P. Bernard ◽  
K. Huang ◽  
S. Bag ◽  
M. Bernacki
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Finite Element ◽  
Dynamic Recrystallization ◽  
Level Set ◽  
Volume Fraction ◽  
Mean Field ◽  
Quantitative Prediction ◽  
Finite Element Approach ◽  
Element Approach

Quantitative prediction of grain size and recrystallized volume fraction is still a real challenge for many alloys, and even for simple materials when subjected to complex thermal/mechanical histories, as in multi-pass (industrial) processing. A first step is therefore taken in the direction of multiscale modelling of recrystallization, by considering digital polycrystalline microstructures. These synthetic mesoscopic microstructures are meshed adaptively and anisotropically, with refinement close to the grain boundaries. Crystal plasticity finite element (CPFEM) simulations are combined with a level set framework to model primary recristallization, following plastic deformation. In the level set method, the kinetic equation describing interface motion uses the calculated stored energy field provided by CPFEM calculations, and works on the same mesh. Discontinuous dynamic recrystallization can be modelled within the same approach, effectively coupling plastic deformation with nucleation and growth processes. Parallel to the finite element approach, a mean field model is developed in the general context of multi-pass processing. The model considers categories of grains based on two state variables : grain size and total dislocation density. As opposed to the finite element approach, there is no crystallographic or topological information. It is computationally much cheaper and therefore suitable for direct coupling at the scale of forming processes, for industrial applications. The parameters of the model can be identified from inverse analysis, using experimental stress-strain curves, recrystallized volume fractions, and grain sizes. Mean field and finite element models are compared, and it is shown that the detailed information provided by finite element simulations can be used to calibrate or optimize the mean field method.

scholarly journals Coupled Cellular Automaton (CA) – Finite Element (FE) Modeling of Directional Solidification of Al-3.5 wt% Ni Alloy: A Comparison with X-ray Synchrotron Observations

2014 ◽  
Vol 54 (2) ◽  
pp. 392-400 ◽  
Author(s):  
Dong Rong Liu ◽  
Guillaume Reinhart ◽  
Nathalie Mangelinck‑Noel ◽  
Charles-André Gandin ◽  
Henri Nguyen-Thi ◽  
...  
Keyword(s):  
Finite Element ◽  
Cellular Automaton ◽  
Directional Solidification ◽  
Fe Modeling ◽  
X Ray ◽  
Ni Alloy

scholarly journals Modelling Microstructure Evolution in ATI 718Plus® Alloy

2016 ◽  
Vol 716 ◽  
pp. 352-359
Author(s):  
Aleksey Reshetov ◽  
Olga Bylya ◽  
Michal Gzyl ◽  
Malgorzata Rosochowska ◽  
Paul Blackwell
Keyword(s):  
Finite Element Analysis ◽  
Grain Size ◽  
Finite Element ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Deformation Process ◽  
Main Trend ◽  
Main Body ◽  
Element Analysis ◽  
Average Grain Size

The present study details the results of finite element analysis (FEA) based predictions for microstructure evolution in ATI 718Plus® alloy during the hot deformation process. A detailed description of models for static grain growth and recrystallisation is provided. The simulated average grain size is compared with those experimentally measured in aerofoil parts after forging trials. The proposed modified JMAK model has proved to be valid in the main body of the forging. The results predicted for the surface are less accurate. The recrystallised grain size on the surface is smaller than in the centre of the part which corresponds to the experimental results and reflects the main trend.

scholarly journals GPU-Accelerated Cellular Automaton Model for Grain Growth during Directional Solidification of Nickel-Based Superalloy

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 298
Author(s):  
Yongjia Zhang ◽  
Jianxin Zhou ◽  
Yajun Yin ◽  
Xu Shen ◽  
Taher A. Shehabeldeen ◽  
...  
Keyword(s):  
Cellular Automaton ◽  
Directional Solidification ◽  
Grain Growth ◽  
Large Scale ◽  
Solidification Process ◽  
Computing Platform ◽  
Nickel Based Superalloy ◽  
Parallel Performance ◽  
Ca Model ◽  
Columnar To Equiaxed Transition

To accelerate the large-scale cellular automaton (CA) simulation for grain growth, a parallel CA model for grain growth was developed. The model was implemented based on the compute unified device architecture (CUDA) parallel computing platform. The model was verified by the grain growth of a single crystal and the columnar-to-equiaxed transition (CET) of an Al-7wt% Si specimen of uniform undercooling with a constant cooling rate. The grid independence of the model was verified. The grain growth of a plate-like casting of nickel-based superalloy during directional solidification process was simulated and the obtained results of grain density at each section with different heights were compared with the experimental data. The CET transition of directional solidified Al-7wt% Si cylindrical ingot was simulated. The grain texture and cooling curves were in good agreement with experimental results from the literature. Finally, high parallel performance of the CA model was obtained and evaluated.

Grain Growth in Vapor Deposited Aluminium Alloys

1986 ◽  
Vol 77 ◽  
Author(s):  
Uwe Köster ◽  
Paul S. Ho
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Growth ◽  
Grain Size Distribution ◽  
Aluminium Alloys ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Quantitative Electron Microscopy ◽  
Grain Sizes ◽  
Grain Coalescence

ABSTRACTIn a number of vapor deposited aluminium alloys grain growth has been investigated systematically by means of quantitative electron microscopy and found to proceed not by grain boundary migration, but by grain coalescence. Parameters influencing the observed mode of grain growth will be discussed with respect to the formation of microstructures with optimal resistance to electromigration, i.e. microstructures with large grain size, high homogeneity in the grain size distribution as well as a strong texture.Analyses of grain size distribution after annealing indicate a strong retardation in grain growth by the solute in all aluminium alloys except Al(Cu). Relative large grain sizes and very small lognormal standard deviations have been observed in Al-l%Cu as well as ternary Al(Cu,Hf) thin films.

Calculating Energy Release Rate as a Function of Crack Length Using a Multiple-Step Crack Closure Technique in Tire Finite Element Models

2018 ◽  
Vol 46 (3) ◽  
pp. 130-152
Author(s):  
Dennis S. Kelliher
Keyword(s):  
Finite Element ◽  
Energy Release Rate ◽  
Crack Length ◽  
Energy Release ◽  
Crack Closure ◽  
Release Rate ◽  
Fatigue Behavior ◽  
Three Dimensions ◽  
Quantitative Prediction ◽  
Closure Technique

ABSTRACT When performing predictive durability analyses on tires using finite element methods, it is generally recognized that energy release rate (ERR) is the best measure by which to characterize the fatigue behavior of rubber. By addressing actual cracks in a simulation geometry, ERR provides a more appropriate durability criterion than the strain energy density (SED) of geometries without cracks. If determined as a function of crack length and loading history, and augmented with material crack growth properties, ERR allows for a quantitative prediction of fatigue life. Complications arise, however, from extra steps required to implement the calculation of ERR within the analysis process. This article presents an overview and some details of a method to perform such analyses. The method involves a preprocessing step that automates the creation of a ribbon crack within an axisymmetric-geometry finite element model at a predetermined location. After inflating and expanding to three dimensions to fully load the tire against a surface, full ribbon sections of the crack are then incrementally closed through multiple solution steps, finally achieving complete closure. A postprocessing step is developed to determine ERR as a function of crack length from this enforced crack closure technique. This includes an innovative approach to calculating ERR as the crack length approaches zero.

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