Numerical Optimization of the Casting of Ceramic Material EUCOR

2011 ◽  
Author(s):  
Frantisek Kavicka ◽  
Jana Dobrovska ◽  
Karel Stransky ◽  
Bohumil Sekanina ◽  
Josef Stetina
Keyword(s):  
Numerical Optimization ◽  
Numerical Models ◽  
Statistical Processing ◽  
Solidification Process ◽  
Quantitative Information ◽  
Solidification Time ◽  
Local Solidification Time ◽  
Material Structure ◽  
Chemical Heterogeneity ◽  
Measurement Results

Corundo-baddeleyit material (CBM) – EUCOR – is a heat- and wear-resistant material even at extreme temperatures. This article introduces a numerical model of solidification and cooling of this material in a non-metallic mold. The model is capable of determining the total solidification time of the casting and also the place of the casting which solidifies last. Furthermore, it is possible to calculate the temperature gradient at any point and time, and also determine the local solidification time and the solidification interval of any point. The local solidification time is one of the input parameters for the cooperating model of chemical heterogeneity. This second model and its application on EUCOR samples prove that the applied method of measuring the chemical heterogeneity provides the detailed quantitative information on the material structure and makes it possible to analyze the solidification process. The analysis of this process entails statistical processing of the measurement results of the heterogeneity of the EUCOR components and performs the correlation of individual components during solidification. The verification of both numerical models was conducted on a real cast 350 × 200 × 400 mm block.

Two Numerical Models for Optimization of the Foundry Technology of the Ceramics EUCOR

Volume 3 ◽  
2004 ◽  
Author(s):  
Jana Dobrovska ◽  
Frantisek Kavicka ◽  
Karel Stransky ◽  
Vera Dobrovska ◽  
Josef Stetina ◽  
...  
Keyword(s):  
Numerical Models ◽  
Statistical Processing ◽  
Solidification Process ◽  
Quantitative Information ◽  
Solidification Time ◽  
Local Solidification Time ◽  
Material Structure ◽  
Chemical Heterogeneity ◽  
Crystallisation Process ◽  
Method Of Measurement

Corundo-baddeleyit material — EUCOR — is a heat- and wear-resistant material even at extreme temperatures. This article introduces a numerical model of solidification and cooling of this material in a non-metallic mould. The model is capable of determining the total solidification time of the casting and also the place of the casting which solidifies last. Furthermore, it is possible to calculate the temperature gradient in any point and time, and also determine the local solidification time and the solidification interval of any point. The local solidification time is one of the input parameters for the cooperating model of chemical heterogeneity. This second model and its application on samples of EUCOR prove that the applied method of measurement of chemical heterogeneity provides detailed quantitative information on the material structure and makes it possible to analyse the solidification process. The analysis of this process entails statistical processing of the results of the measurements of the heterogeneity of the components of EUCOR and performs correlation of individual components during solidification. The crystallisation process seems to be very complicated, where the macro- and microscopic segregations differ significantly. The verification of both numerical models was conducted on a real cast 350 × 200 × 400 mm block.

Original Industrial Application of two Numerical Models in Concasting Technology

2011 ◽  
Vol 291-294 ◽  
pp. 411-417
Author(s):  
František Kavička ◽  
Jana Dobrovská ◽  
Karel Stránský ◽  
Bohumil Sekanina ◽  
Josef Stetina ◽  
...  
Keyword(s):  
Solid State ◽  
Cross Section ◽  
Industrial Application ◽  
Numerical Models ◽  
Mathematical Statistics ◽  
Internal Crack ◽  
Chemical Heterogeneity ◽  
Steel Slab ◽  
Measurement Results ◽  
Analytical Equipment

This paper deals with the causes of a transversal crack in a steel slab with an l300×l45 mm cross-section by means of results from two models. Samples were taken from and around the crack in order to analyze the concentration (chemical heterogeneity) of the selected elements. Simultaneously, the concentration of elements at the surface of the crack was measured after the crack was opened. The chemical heterogeneity of elements was analyzed by means of the JEOL JXA 8600/KEVEX analytical equipment. The measurement results were processed using mathematical statistics procedures. The results proved that there was an internal crack initiating immediately below the curve of the solid-state temperature and consecutively propagating.

Cooling of a Massive Casting of Ductile Cast-Iron and Its Numerical Optimization

2009 ◽  
Author(s):  
Frantisek Kavicka ◽  
Karel Stransky ◽  
Bohumil Sekanina ◽  
Jana Dobrovska ◽  
Josef Stetina
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Temperature Field ◽  
Cast Iron ◽  
Numerical Optimization ◽  
Numerical Models ◽  
Ductile Cast Iron ◽  
Chemical Heterogeneity ◽  
Numerical Finite Element ◽  
Original Application

The numerical models of the temperature field of solidifying castings often observe two main goals: directed solidification and optimization of the technology. These goals can be achieved only if the deciding factors which either characterize the process or accompany it are analysed and their influence controlled. An original application of ANSYS, based on the numerical finite-element method, is applied. The numerical model simulated the forming of the temperature field of a two-ton 500×500×1000 mm casting from ductile cast-iron during the application of various methods of its cooling using steel chills. This model managed to optimize more than one method of cooling but, in addition to that, provided results for the successive model of structural and chemical heterogeneity, and so it also contributes to influencing the pouring structure. The file containing the acquired results from both models, as well as from their organic unification, brings new and, simultaneously, remarkable findings of causal relationships between the structural and chemical heterogeneity and the local solidification time in any point of the casting. This has established a tool for the optimization of the structure with an even distribution of the spheroids of graphite in such a way so as to minimize the occurrence of degenerated shapes of graphite, which is one of the conditions for achieving good mechanical properties of castings of ductile cast-iron.

Effects of Solidification Parameters on SDAS of A357 Alloy

2008 ◽  
Vol 51 ◽  
pp. 85-92 ◽  
Author(s):  
Juan He ◽  
Jian Min Zeng ◽  
Along Yan
Keyword(s):  
Cooling Rate ◽  
Solidification Time ◽  
Local Solidification Time ◽  
A357 Alloy ◽  
Solidification Condition ◽  
Alloy Casting ◽  
Furan Resin ◽  
Solidification Parameters ◽  
Relationship Of ◽  
The Relationship

In this investigation, experiments were carried out to study the relationship of solidification parameters and the secondary dendrite arm spacing (SDAS) in A357 alloy casting with various thicknesses under the same solidification condition. The results show that the cooling rate decreases as the thickness of specimens increases, the local solidification time increased, and SDAS increased. The relationships between the SDAS and cooling rate and local solidification time under the condition of furan resin self-hardening sand casting were obtained: SDAS = 20.8 tf 0.3, SDAS = 69.34 v -0.3. The mechanical properties have some linear relations with SDAS of A357 alloy after aging heat treatment. The correlations can be expressed: UTS=410.4-0.8SDAS and El%=7.9-0.05SDAS.

Characterization of AM60 Magnesium Alloy Prepared by Rapid Solidification and Plastic Consolidation Technique

2010 ◽  
Vol 667-669 ◽  
pp. 997-1002
Author(s):  
Tomasz Tokarski
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Rapid Solidification ◽  
Melt Spinning ◽  
Bulk Material ◽  
Structure Refinement ◽  
Hot Extrusion ◽  
Solidification Process ◽  
Protective Atmosphere ◽  
Material Structure

Magnesium and its alloys are attractive candidates for automotive and aerospace applications due to their relatively high strength and low density. However, their low ductility determined by hcp structure of material results in limitation of plastic deformation processing. In order to improve ductility as well as mechanical properties, structure refinement processes can be used. It is well known that effective refining of the material structure can be achieved by increasing the cooling rate during casting procedures, hence rapid solidification process (RSP) has been experimented for the fabrication of magnesium alloys. The present paper reports an experimental investigation on the influence of rapid solidification on the mechanical properties of AM60 magnesium alloy. In order to obtain RS material melt spinning process was applied in protective atmosphere, resulting in formation of RS ribbons. Following consolidation of the RS material is necessary to obtain bulk material with high mechanical properties, as so hot extrusion process was applied. It was noticed that application of plastic consolidation by hot extrusion is the most effective process to achieve full densification of material. For comparison purposes, the conventionally cast and hot extruded AM60 alloy was studied as well. The purpose of the present study was to investigate in detail the effect of rapid solidification and extrusion temperature on the structure and mechanical properties of the materials.

Flow Control during Solidification of AlSi-Alloys by Means of Tailored AC Magnetic Fields and the Impact on the Mechanical Properties

2014 ◽  
Vol 790-791 ◽  
pp. 384-389
Author(s):  
Dirk Räbiger ◽  
Bernd Willers ◽  
Sven Eckert
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Grain Size ◽  
Magnetic Fields ◽  
Flow Field ◽  
Phase Distribution ◽  
Solidification Process ◽  
Quantitative Information ◽  
Rotating Magnetic Field ◽  
The Impact

This paper presents an experimental study which in a first stage is focused on obtaining quantitative information about the isothermal flow field exposed to various magnetic field configurations. Melt stirring has been realized by utilizing a rotating magnetic field. In a second step directional solidification of AlSi7 alloys from a water-cooled copper chill was carried out to verifythe effect of a certain flow field on the solidification process and on the resulting mechanical properties. The solidified structure was reviewed in comparison to an unaffected solidified ingot. Measurements of the phase distribution, the grain size, the hardness and the tensile strength were realized. Our results demonstrate the potential of magnetic fields to control the grain size, the formation of segregation freckles and the mechanical properties. In particular, time–modulated rotating fields show their capability to homogenize both the grain size distribution and the corresponding mechanical properties.

Understanding Channel Segregates in Numerical Models of Alloy Solidification: A Case of Converge First and Ask Questions Later

2014 ◽  
Vol 790-791 ◽  
pp. 73-78 ◽  
Author(s):  
Igor Vušanović ◽  
Vaughan R. Voller
Keyword(s):  
Numerical Models ◽  
Solidification Rate ◽  
Grid Cell ◽  
Solidification Process ◽  
Solute Concentration ◽  
Heat Transfer Fluid ◽  
Mushy Region ◽  
High Concentration ◽  
Flow Paths ◽  
Grid Convergence

In static castings of multi-component alloys, visually observable bands of channels, with high solute concentration, can form in the final solidified product. The phenomenological explanation for these formations is that perturbations during the solidification process lead to preferred flow paths in the solid-liquid mushy region. Once these flow paths are initiated, the higher solute liquid that flows in them suppresses the solidification rate and thus provides a mechanism through which the preferred paths can evolve into high concentration channels. Models of solidification that couple heat transfer, fluid and flow and mass transport appear able to predict the formation of these channels. In many cases, however, the formation of these numerical channels is highly dependent on the nature of the numerical calculation. In particular, geometric attributes of the channels is a strong function of the size of the computational grid and in some cases the particular method (code) used. In this work, after discussing what might drive the observed discrepancies in predictions, a grid convergence study is undertaken. This study shows that for the case of a side cooled solidification of a binary (Al-4.5wt%Cu) in a square (40mm x 40mm) domain, it is possible to approach grid converged results of the solution of the standard mixture model for macrosegregation. Achieving this level of convergence requires the use of an explicit time stepping scheme to couple the thermal and solute fields along with a Carman-Kozeny permeability and lever rule microsegregation models. The results indicate that to reach grid convergence the size of a grid cell has to be on the order ~0.25-0.5 mm.

Analysis of a Transversal Crack in a Steel Slab

2007 ◽  
Vol 567-568 ◽  
pp. 105-108 ◽  
Author(s):  
Jana Dobrovská ◽  
Karel Stránský ◽  
František Kavička ◽  
Josef Stetina ◽  
Zdenek Franek
Keyword(s):  
Solid State ◽  
Cross Section ◽  
Mathematical Statistics ◽  
Internal Crack ◽  
Chemical Heterogeneity ◽  
Steel Slab ◽  
Measurement Results ◽  
Analytical Equipment

This paper deals with an analysis of the possible causes of a transversal crack in a steel slab with a l300×l45 mm cross-section using results from two models. Samples were taken from and around the crack in order to analyze the concentration (i.e. chemical heterogeneity) of the relevant elements. Simultaneously, the concentration of elements at the surface of the crack was measured after the crack was opened. The chemical heterogeneity of elements was analyzed with the aid of the JEOL JXA 8600/KEVEX analytical equipment. The measurement results were processed using mathematical statistics procedures. The results proved that there was an internal crack initiating immediately below the curve of the solid-state temperature and consecutively propagating.

Modular ultrasound platform for flow mapping in magnetohydrodynamics

2015 ◽  
Vol 82 (11) ◽  
Author(s):  
Kevin Mäder ◽  
Richard Nauber ◽  
Hannes Beyer ◽  
Arne Klaß ◽  
Norman Thieme ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Phased Array ◽  
Liquid Metals ◽  
Numerical Models ◽  
Sound Field ◽  
Solidification Process ◽  
Flow Mapping ◽  
Ultrasound Doppler ◽  
Model Experiments ◽  
Array Ultrasound

AbstractFlow control based on time-dependent magnetic fields is used in various industrial processes involving liquid metals, i. e. during the solidification process of silicon to improve the quality and efficiency of wafers. In order to investigate the interactions between spatiotemporal-varying magnetic fields and conductive fluids numerical simulations are performed. The numerical models are verified by model experiments with opaque low-melting alloys. A suitable measurement technique for flow mapping in such model experiments is ultrasound Doppler velocimetry. In contrast to conventional systems employing transducers with fixed sound field our approach is to use a phased array with the ability to focus and steer its acoustic field. We present the Phased Array Ultrasound Doppler Velocimeter (PAUDV) for flow mapping in magnetohydrodynamics. With its custom host software for control and signal processing experiments that are flexible regarding the experimental setup can be defined.

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