On the characterization of eutectic grain growth during solidification

ABSTRACTThe purpose of this work is to compare the results obtained from three methodologies intended to estimate kinetic parameters describing quantitatively the grain growth during equiaxed eutectic solidification in order to identify the best procedure to characterize grain growth kinetics. A heat transfer / solidification kinetics model is implemented to simulate the cooling and solidification of eutectic Al-Si and eutectic cast iron in sand molds. Using simulated cooling curves and volume grain density data generated by the model, the three methods are applied to obtain their predicted grain growth coefficients. The predicted results are compared with the grain growth coefficients used in the model. The outcome of this work suggests that two of the three methods under study represent the best option to obtain the kinetic parameters of equiaxed growth during eutectic solidification.

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Numerical Processing of Cooling Curves to Obtain Growth Parameters During Eutectic Solidification

MRS Proceedings ◽

10.1557/opl.2012.303 ◽

2012 ◽

Vol 1373 ◽

Author(s):

M. Morua ◽

E. Peña ◽

R. Aparicio ◽

M. Ramirez-Argaez ◽

C. Gonzalez-Rivera

Keyword(s):

Kinetic Parameters ◽

Grain Growth ◽

Growth Parameters ◽

Mechanistic Model ◽

Eutectic Solidification ◽

Exponential Dependence ◽

Cooling Curves ◽

Numerical Processing ◽

Fourier Thermal Analysis ◽

Grain Growth Kinetics

ABSTRACTIn this work a methodology to measure kinetic parameters to describe grain growth during equiaxed eutectic solidification is proposed. This methodology includes the numerical processing of two cooling curves and requires input data concerning the number of grains per unit volume. In addition, free grain growth before impingement and an exponential dependence of the grain growth rate on undercooling are assumed. The evolution of solid fraction of the sample as a function of time is obtained by applying the Fourier thermal analysis (FTA) method. Information collected is processed numerically in order to find numerical values for the pre-exponential and exponential parameters that characterize the grain growth kinetics as a function of undercooling. To validate this methodology a mechanistic model that simulates the cooling and solidification of eutectic Al-Si alloy in a sand mold is used. The results suggest that this methodology can be used to measure the kinetic parameters of equiaxed growth from the numerical processing of cooling curves and grain density data.

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Thermal and Kinetic Analysis of the solidification of a near eutectic Al-Cu Alloy

MRS Proceedings ◽

10.1557/opl.2014.765 ◽

2014 ◽

Vol 1611 ◽

pp. 105-110

Author(s):

M. Morua ◽

M. Ramirez-Argaez ◽

C. Gonzalez-Rivera

Keyword(s):

Heat Transfer ◽

Thermal Analysis ◽

Kinetic Analysis ◽

Eutectic Growth ◽

Eutectic Solidification ◽

Cooling Curves ◽

Transfer Coefficients ◽

Fourier Thermal Analysis ◽

Cu Alloy ◽

Solidification Kinetics

ABSTRACTIn this work the thermal and kinetic analysis of the cooling and solidification of a near eutectic Al-Cu alloy is performed using inverse thermal and solidification kinetics analysis. The Fourier thermal analysis is applied to experimental cooling curves to obtain data on solid fraction evolution and latent heat of solidification. Inverse thermal analysis is applied to calculate the global heat transfer coefficients that allow correct simulation of the cooling of experimental probes. The free growth method is used to obtain the eutectic growth coefficients. All the obtained parameters are feed into a heat transfer-solidification kinetics model to validate the methodology and results generated from this work. It is found a relatively good agreement between experimental and predicted cooling curves which suggest that this methodology could be used to generate useful information needed to simulate eutectic solidification.

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Macro-Micro Modeling and Simulation of Solidification Kinetics of Pb-Sn Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.509.171 ◽

2006 ◽

Vol 509 ◽

pp. 171-176

Author(s):

L. López ◽

H. Cruz ◽

B. Campillo ◽

Carlos González-Rivera

Keyword(s):

Heat Transfer ◽

Solidification Rate ◽

Primary Phase ◽

Experimental Results ◽

Eutectic Solidification ◽

Cooling Curves ◽

Solidification Kinetics ◽

Eutectic Morphology ◽

Micro Modeling ◽

Kinetics Of

The purpose of this work is to explore the effect of the presence of two different primary phases on the microstructure and solidification kinetics of Pb-Sn alloys. The experimental results have been compared with predictions obtained from the Newton Thermal Analysis of cooling curves generated by a conventional heat transfer-solidification kinetics model. Three Pb-Sn alloys have been considered in this work in order to explore the solidification characteristics of the eutectic in hypoeutectic, hypereutectic and eutectic compositions. Experimental results indicate that the Pb-Sn eutectic morphology and the solidification rate depend on the nature of the pre-existent primary phase during eutectic solidification. From the observed discrepancies between experimental and simulated results it is concluded that further improvements are needed to simulate the solidification kinetics of eutectic microconstituents in the presence of pre-existing primary phases.

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Influence of Ti on Graphite Morphological Transition in Flake Graphite Cast Iron

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.457.25 ◽

2010 ◽

Vol 457 ◽

pp. 25-30 ◽

Cited By ~ 5

Author(s):

Hideo Nakae ◽

Kyohei Fujimoto

Keyword(s):

Cast Iron ◽

Volume Fraction ◽

Solidification Rate ◽

Eutectic Solidification ◽

Morphological Transition ◽

Cooling Curves ◽

Shell Mold ◽

Solidification Mode ◽

Volume Fractions ◽

Ti Addition

The morphological transition from the A-type to D-type graphite (undercooled graphite) in cast iron has been studied using Fe-3.5%C-2.0%Si-0/0.1%Ti samples. The samples were prepared using a high frequency induction furnace flowing Ar atmosphere using 0.25% steel rods with or without Ti addition. The samples had Ti contents that ranged from 0 to 0.10% at 5 different levels by the addition of sponge titanium. The cooling curves of these melts were measured in a shell mold with an inside diameter of 30mm and 50mm height and in four BN-coated steel cup molds with a volume of 30ml each. The cooling curves were measured by CA thermocouples located at the center. The cooling curves were differentiated to determine the transition points, namely the onset and end points of the eutectic solidification. Three out of the four samples, solidifying in steel molds, were quenched during the eutectic solidification and their macro-structures and micro-structures were observed for the determining the solidification mode. The volume fractions of the D-type graphite area in the samples were measured using 30 microscope images of 50× magnification, and their eutectic temperature was also determined using their cooling curves. The volume fraction of the shell mold samples increased with the Ti addition from 5% to 55%, and if the Ti content was greater than 0.05%, the acceleration occurred with their maximum undercooling, ΔTMAX. The critical undercooling temperature, TA/D, and the critical solidification rate, RA/D, of the A-type to D-type graphite transition were determined by comparing the volume fractions to the solidification time. The ΔTMAX　and TA/D values increased with the Ti addition. This is the main reason why the Ti addition accelerates the D-type graphite increase.

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A rapid approach to estimate the mechanical properties of grey cast iron castings

Acta Metallurgica Slovaca ◽

10.12776/ams.v24i3.1146 ◽

2018 ◽

Vol 24 (3) ◽

pp. 213 ◽

Cited By ~ 2

Author(s):

Paolo Ferro ◽

Thomas Borsato ◽

Franco Bonollo ◽

Stefano Padovan

Keyword(s):

Mechanical Properties ◽

Cast Iron ◽

Master Curve ◽

Mechanical Characterization ◽

Grey Cast Iron ◽

Iron Castings ◽

Solidification Kinetics ◽

Grey Cast ◽

Microstructure Morphology

<p>Grey cast iron is a brittle or quasi-brittle material very sensitive to the microstructure morphology deriving from its solidification kinetics. This is the reason why different zones of a casting, even with the same thickness, may be characterized by different mechanical properties according to the solidification time. The mechanical characterization of the alloy made by following the Standards that refer to values obtained from separately casted samples is insufficient for a designer who needs to know the specific properties of the material in each zone of interest of the casting. In this work a method is described to predict the mechanical properties of castings made of GH 190 cast iron that correlates the solidification times with the ultimate tensile strength through a master curve, supposed to depend only on alloy chemical composition. This predictive approach was successfully validated with experimental mechanical characterization of a real industrial casting.</p>

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Effect of Latent Heat Related to Solidification Kinetics on Heat Transfer during Solidification of Al Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.884-885.273 ◽

2014 ◽

Vol 884-885 ◽

pp. 273-276

Author(s):

Seok Jae Lee

Keyword(s):

Heat Transfer ◽

Latent Heat ◽

Temperature Compensation ◽

Solid Phase ◽

A356 Alloy ◽

Cooling Curve ◽

Al Alloy ◽

Cooling Curves ◽

Solidification Kinetics ◽

Heat Transfer Simulation

The effect of the latent heat related to the rate of the solidification kinetics during solidification was investigated by using the heat transfer simulation. The latent heat was generated proportional to the amount of the fraction of transformed solid phase and directly affected the temperature compensation during solidification. The importance of the solidification kinetics was discussed by comparing cooling curves calculated using different solidification kinetics with experimentally measured cooling curve of A356 alloy.

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A Study of the Convective Cooling of Large Industrial Billets

Journal of Manufacturing and Materials Processing ◽

10.3390/jmmp5040137 ◽

2021 ◽

Vol 5 (4) ◽

pp. 137

Author(s):

Richard Turner

Keyword(s):

Heat Transfer ◽

Convective Heat Transfer ◽

Convective Heat ◽

Cooling Curves ◽

Temperature Dependent ◽

Fundamental Relationship ◽

Grain Growth Kinetics ◽

Value Model ◽

Transfer Mechanisms ◽

Cooling Model

The thermodynamic heat-transfer mechanisms, which occur as a heated billet cools in an air environment, are of clear importance in determining the rate at which a heated billet cools. However, in finite element modelling simulations, the convective heat transfer term of the heat transfer mechanisms is often reduced to simplified or guessed constants, whereas thermal conductivity and radiative emissivity are entered as detailed temperature dependent functions. As such, in both natural and forced convection environments, the fundamental physical relationships for the Nusselt number, Reynolds number, Raleigh parameter, and Grashof parameter were consulted and combined to form a fundamental relationship for the natural convective heat transfer as a temperature-dependent function. This function was calculated using values for air as found in the literature. These functions were then applied within an FE framework for a simple billet cooling model, compared against FE predictions with constant convective coefficient, and further compared with experimental data for a real steel billet cooling. The modified, temperature-dependent convective transfer coefficient displayed an improved prediction of the cooling curves in the majority of experiments, although on occasion a constant value model also produced very similar predicted cooling curves. Finally, a grain growth kinetics numerical model was implemented in order to predict how different convective models influence grain size and, as such, mechanical properties. The resulting findings could offer improved cooling rate predictions for all types of FE models for metal forming and heat treatment operations.

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Spark Plasma Sintering and Microstructural Characterization of Additive-Free Polycrystalline β-SiC

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.423.67 ◽

2009 ◽

Vol 423 ◽

pp. 67-72 ◽

Cited By ~ 5

Author(s):

A. Lara ◽

R. Poyato ◽

A. Muñoz ◽

A.L. Ortiz ◽

Arturo Domínguez-Rodríguez

Keyword(s):

Grain Growth ◽

Spark Plasma Sintering ◽

Sintering Temperature ◽

Microstructural Characterization ◽

Holding Time ◽

Plasma Sintering ◽

Final Microstructure ◽

Spark Plasma ◽

Grain Growth Kinetics

Additive-free -SiC powders were sintered by means of Spark Plasma Sintering System. Experiments were performed in the temperature range from 1650°C to 2200°C, 3 to 10 min holding time and pressure from 50 until 150 MPa. In order to favour sinterization, the starting powder was mechanically activated: defect concentration was increased by centrifugal ball milling. Applied temperature, holding time and/or pressure were varied to analyze their effect on the densification and grain growth kinetics. The full sinterization of the material was obtained for temperatures as high as 1900°C and over. The relative density of the obtained material was high, up to 97.0  0.6 % the theoretical density for 2200°C sintering temperature. An intense grain growth took place while sintering. The final microstructure exhibited a grain size distribution range from 1.0 to 2.5 m, depending on the sintering conditions. Such grain growth strongly depends on the sintering time, not so much on the sintering temperature.

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