Determination of dendrite coherency point characteristics using first derivative curve versus temperature

Djurdjevic, Mile B.; Sokolowski, J. H.; Odanović, Zoran

doi:10.1007/s10973-012-2490-4

Cited by 38 publications

(23 citation statements)

References 3 publications

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“…Colas and a group of authors (Chávez-Zamarripa et al, 2007) applied three thermocouples located in the centre, middle, and close to the wall of steel and graphite crucibles to measure the variation in the thermal diffusivity of A319 alloy (AlSi7Cu3). Comparing this method with the other aforementioned methods, it was concluded that all three methods yield similar results and can be used to evaluate the DCP temperature (Djurdjevic et al, 2012b).…”

Section: Dendrite Coherency Temperaturementioning

confidence: 92%

“…Recently, several authors (Djurdjevic et al, 2001b;Chávez-Zamarripa et al, 2007;Djurdjevic et al, 2012b;Djurdjevic et al, 2012c;Krohn , 1985 andCanales, 2010) have started to use the first derivative versus temperature plot in order to simplify the detection of the solidification characteristic events during the solidification process, since they can be read directly from the first derivative curves, as shown in Figure 7.…”

Section: Derivative Curves Plotted Versus Temperaturementioning

confidence: 99%

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Review of thermal analysis applications in aluminium casting plants

Djurdjevic¹,

Vicario²,

Huber³

2014

REVMETAL

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SUMMARY:Thermal analysis has been applied as a quality control tool in aluminium casting plants for many years. Recently, it has been recognized that the cooling curve and its first derivative analysis offer parameters that can successfully be used in simulation software programs to improve simulation accuracy. The latest developments in cooling curve analysis are related to the application of higher order derivatives, showing that the thermal analysis technique can be applied to calculate the total amounts of different phases precipitated in the solidification process, including copper-rich eutectic. This paper gives a short overview of cooling curve applications in aluminium casting plants, and the impact of lead on solidification characteristic temperatures of AlSi6Cu4 alloy. RESUMEN:Revisión de las aplicaciones del análisis térmico en las plantas de fundición de aluminio. El análisis térmico ha sido usado como una herramienta de control de calidad desde hace tiempo en las plantas de fundición de aluminio. Recientemente ha sido reconocido que el análisis de la curva de enfriamiento y su primera derivada ofrecen algunos otros parámetros que pueden ser usados de manera exitosa en los programas de simulación para mejorar su precisión. Los nuevos desarrollos en el análisis de la curva de enfriamiento aplicando las derivadas de orden superior han mostrado que la técnica del análisis térmico puede aplicarse para calcular la cantidad de precipitados en el proceso de solidificación. Este artículo proporciona una pequeña revisión de la aplicación de la curva de enfriamiento en las plantas de fundición de aluminio y del efecto del plomo sobre las temperaturas características de solidificación de la aleación AlSi6Cu4.

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Section: Dendrite Coherency Temperaturementioning

confidence: 92%

Section: Derivative Curves Plotted Versus Temperaturementioning

confidence: 99%

Review of thermal analysis applications in aluminium casting plants

Djurdjevic¹,

Vicario²,

Huber³

2014

REVMETAL

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“…The point of dendritic coherency can be determined by rheological means or by thermal analysis technique. [9][10][11] In the rheological technique, a rotating impeller is immersed into a solidifying alloy and the torque is recorded as a function of the temperature of the melt. A sudden increase in torque is associated with the point at which the dendrites start to touch, impeding the free rotation of the impeller.…”

Section: Introductionmentioning

confidence: 99%

“…[13,16] The DCP is then determined by measuring the maximum point of the temperature difference. This technique is used by Gholizadeh et al, [5,17] Djurdjevic et al, [10] and other researchers. [18] The single thermocouple method is based on the assumption that solidification affects the cooling rate of the material, and as a consequence, a minimum value in the second derivative of the temperature with respect to time (d 2 T/dt 2 ) will be found.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rate on the Dendrite Coherency Point During Solidification of Al2024 Alloy

Ghoncheh

Shabestari

2014

Metall Mater Trans A

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Most research related to dendrite coherency point (DCP) has been done on cast aluminum alloys and at a low cooling rate condition. In this research, the DCP of a wrought aluminum alloy is calculated in the range of high cooling rates used in the direct-chill casting process. The two-thermocouple thermal analysis technique was used to determine the DCP of Al2024 alloy. The aim of this work is to investigate the effect of different cooling rates on the dendrite coherency characteristics of Al2024. The cooling rates used in the present study range from 0.4 to 17.5°C s À1 . Also, the effect of 1.2 wt pct Al-5Ti-1B grain refiner on the DCP was studied. To calculate the solid fraction at dendrite coherency, solid fraction versus time is plotted based on Newtonian technique. The results show that by increasing the cooling rate, both time and temperature of dendrite coherency are decreased. Also, by adding the Al-5Ti-1B master alloy, dendrite coherency temperature is reduced and dendrite impingement is postponed. To reduce casting defects occurring during equiaxed solidification, e.g., macrosegregation, porosities, and hot tearing, these two operations which lead to postpone the transition from mass to interdendritic feeding, or dendrite coherency, can be useful. By increasing the cooling rate, solid fraction at dendrite coherency increases initially and then decreases at higher cooling rates. Presence of grain refiner leads to increasing of solid fraction at DCP. Thus, by delaying the dendrite coherency and increasing the solid fraction at DCP, semi-solid forming can be performed on parts with higher solid fraction and less shrinkage. Microstructural evaluation was carried out to present the correlation between the cooling rate and solid fraction in 2024 aluminum alloy.

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“…It is based on the measurement and analysis of the temperature of cooling sample in a small cup. CA-CCA techniques include the determination of liquidus and solidus temperature [5], grain refinement [6,7], phase transitions [4,8,9], dendrite coherency point [2,10], solid fraction, and latent heat [4,11,12]. Cooling curve analysis has been applied using various methods for several types of alloys in metallurgical applications [2][3][4][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

A new baseline for the Newtonian thermal analysis of casting: two-capacitive system baseline

Erbaş

2014

J Therm Anal Calorim

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Computer-aided cooling curve thermal analysis for the casting process is usually applied to predict the latent heat of transformation and the solid fraction. In this study, one of the important limitations of the Newtonian thermal analysis for the prediction of the latent heat was determined as the disregard of the thermal capacity of mold. Therefore, a new baseline technique, two-capacitive system baseline (TCSBL), was developed by taking the thermal capacity of the mold into account. This new method was modeled by considering the analogy between RC circuits and the metal-mold thermal capacitance system. It was improved by a Taylor series expansion approach to express the cooling rates in terms of the metal and mold temperatures. Ten experiments with four types of pure metals were undertaken to compare the latent heat results of TCSBL with the Newtonian and Dynamic Baselines (NBL and DBL). The mean percentage error for the latent heat prediction of TCSBL, NBL, and DBL were calculated as 4.3, 29, and 24 %, respectively, in comparison with the literal value of the latent heats.

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Determination of dendrite coherency point characteristics using first derivative curve versus temperature

Cited by 38 publications

References 3 publications

Review of thermal analysis applications in aluminium casting plants

Review of thermal analysis applications in aluminium casting plants

Effect of Cooling Rate on the Dendrite Coherency Point During Solidification of Al2024 Alloy

A new baseline for the Newtonian thermal analysis of casting: two-capacitive system baseline

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