Effect of Mould Heating Temperature on Cooling Rate of the Melt upon Bronze Crystallization

2014 ◽  
Vol 682 ◽  
pp. 231-235 ◽  
Author(s):  
Nikita Martyushev ◽  
Yuriy N. Petrenko
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Heating Temperature ◽  
Numerical Data ◽  
Cooling Curves ◽  
Cooling Rates ◽  
Thermal Electromotive Force ◽  
Alumel Thermocouple ◽  
Melt Cooling ◽  
Graphite Mould

The article presents the cooling curves of the tin-leaded bronze melt (consists of 10% of lead, 10% of tin, and 80% of copper) being poured in the moulds of various thermal conductivities: massive cast iron chill mould (with the 1:8 cast mass to mould mass ratio) and graphite mould. The curves were plotted for the moulds previously heated to the temperatures of 20; 200; 400; 600; 800 °С. Plotting of the curves was performed with the use of the device Thermograph designed at Tomsk Polytechnic University. The device records thermal electromotive force values of the chromel-alumel thermocouple and converts them into temperature values. The cooling curves are used to determine melt cooling rates within the temperature range involving the crystallization range. It is shown that under similar conditions the cooling rate when casting in cast iron mould is 30-40% higher than in the case of casting in graphite mould. The data given in the paper indicate that preheating of the mould enables us to considerably reduce the cast cooling rate and prolong the period of the melt being in liquid state. It is worth mentioning that cooling rate values of the preheated and non-heated casting moulds are most vividly observed at the initial moments after the melt pouring. When decreasing the casts’ cooling to 300-400 °С the cooling rates tend to be identical. In the article, the numerical data of cooling rates for various mould heating temperatures are presented.

The Influence of Cooling Rate and Equivalent Carbon on the Chill Tendency and Cooling Curves Parameters in Uninoculated and Inoculated Grey Cast Iron

2016 ◽  
Vol 254 ◽  
pp. 255-260
Author(s):  
Elena Panciu ◽  
Denisa Elena Anca ◽  
Mihai Chisamera
Keyword(s):  
Cast Iron ◽  
Comparative Analysis ◽  
Cooling Rate ◽  
Experimental Research ◽  
Grey Cast Iron ◽  
Carbon Equivalent ◽  
Cooling Curves ◽  
Cast Irons ◽  
Grey Cast ◽  
Equivalent Carbon

The main objectiv of this experimental research is a comparative analysis of the changes caused by varying both of cooling rate and carbon equivalent content on depth of chill tendency and cooling curves parameters of grey cast irons.

Validation of a Simple Two-Point Method To Assess Restaurant Compliance with Food Code Cooling Rates

2020 ◽  
Vol 84 (1) ◽  
pp. 6-13
Author(s):  
MATTHEW J. IGO ◽  
NICOLE HEDEEN ◽  
DONALD W. SCHAFFNER
Keyword(s):  
Cooling Rate ◽  
Screening Tool ◽  
Point Method ◽  
Cooling Curves ◽  
Simple Linear Regression ◽  
Point Model ◽  
Slow Cooling ◽  
Cooling Rates ◽  
Novel Method ◽  
Almost All

ABSTRACT Outbreaks from improperly cooled foods continue to occur despite clearly described Food Code cooling guidelines. It is difficult for regulators to enforce these guidelines because they are typically in an establishment for less than the 6 h needed to document proper cooling. Prior research proposed using a novel method to estimate cooling rates based on two time-temperature points, but this method has not yet been validated. Time-temperature profiles of 29 different foods were collected in 25 different restaurants during cooling. Cooling curves were divided into two categories: typical (21 foods) and atypical (eight foods) prior to further analysis. Analysis of the typical cooling curves used simple linear regression to calculate cooling rates. The atypical cooling profiles were studied using Monte Carlo simulations of the cooling rate. Almost all linearized typical cooling curves had high (>0.90) R2 values. Six foods with typical cooling profiles that did not pass Food Code cooling times were correctly identified by the two-point model as having slow cooling rates. Three foods that did not pass Food Code cooling times were identified by the two-point model as having marginal cooling rates. Ten of 12 foods identified by the two-point model as having acceptable cooling rates met Food Code cooling times. Most (six of eight) foods that were considered to have atypical cooling curves failed to meet the Food Code cooling times. The two-point model was also able to determine whether these foods would fail based on Food Code guidelines depending upon the simulation criteria used. Our data show that food depth has a strong influence on cooling rate. Containers with a food depth ≥7.6 cm (3 in.) were more likely to have cooling rates slower than the U.S. Food and Drug Administration Model Food Code cooling rate. This analysis shows that the two-point method can be a useful screening tool to identify potential cooling rate problems during a routine restaurant inspection visit. HIGHLIGHTS

Effect of Cooling Rate on Drop-Tube Processed Commercial Grey Cast Iron

2015 ◽  
Author(s):  
Olamilekan R. Oloyede ◽  
Tim Bigg ◽  
Andrew M. Mullis
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Microstructural Analysis ◽  
Control Sample ◽  
Grey Cast Iron ◽  
Drop Tube ◽  
Flake Graphite ◽  
Cooling Rates ◽  
Grey Cast

This study focuses on the fundamental of solidification of commercial grey cast iron as a function of the externally applied cooling rate. Grey cast iron powders were prepared using the drop-tube method, which is a good analogue for commercial production via high pressure gas atomization. The as-solidified droplets were collected and sieved into size ranges from > 850 μm to < 53 μm diameter, with estimated cooling rates of 500 K s−1 to 75,000 K s−1, with each sieve fraction being prepared for metallographic characterization. The microstructure and phase composition of the powders were analyzed using XRD, optical and scanning electron microscopy, with the results being compared against a control sample subject to slow cooling in the drop-tube crucible; which has typical grey cast iron microstructure with extensive flake graphite in a largely ferrite matrix. In contrast, flake graphite was absent in virtually all the drop-tube samples, even in those with the most modest cooling rates. Microstructural analysis revealed that as the cooling rate increased there was less fragmentation of the primary austenite/ferrite dendrites and the volume fraction of primary dendritic material increased. Hence, as the particle fractions get smaller (D < 106 μm) there is a distinct microstructural evidence of a martensite phase which is related to its better mechanical properties (microhardness) as the sample sizes decrease.

Thermal Profiles and Fraction Solid of Aluminium 7075 at Different Cooling Rate Conditions

2013 ◽  
Vol 554-557 ◽  
pp. 582-595 ◽  
Author(s):  
Asnul Hadi Ahmad ◽  
Sumsun Naher ◽  
Dermot Brabazon
Keyword(s):  
Cooling Rate ◽  
Air Flow ◽  
Phase Changes ◽  
Crucible Wall ◽  
Cooling Curves ◽  
Cooling Rates ◽  
Labview Software ◽  
Fraction Solid ◽  
Forced Air ◽  
Semi Solid

In order to determine suitable processing conditions for semi-solid aluminium 7075 thermal analysis (TA) was performed in order to obtain the relationship between fraction solid and temperature. During experimental work, the alloy was heated to 750°C by induction furnace and solidified at various cooling rates. Cooling curves for the metal were recorded with two thermocouples, one at the centre of the melt volume and one beside the containing crucible wall. A specially designed chamber with kaowool blanket was used to achieve the slowest cooling rate. The faster cooling rate was achieved with the crucible in open atmosphere with a set air flow rate over the crucible. A Data Acquisition (DAQ) system controlled by LabVIEW software was used to record the temperature-time profiles. From these cooling curves, the phase change at any corresponding time and temperature was estimated. The temperature difference between centre and wall of crucible was used to determine dendritic coherency point (DCP). Results show that, the slowest cooling rate with the kaowool blanket was at 0.03°C/s. An intermediate cooling rate of 0.21°C/s was achieved by leaving the melt to cool without kaowool blanket or forced air flow, and the fastest cooling rate was 0.43°C/s. The change in cooling rate altered the temperatures at which phase changes occurred, including those for eutectic and solidus. It was found that for lower the cooling rates that the DCP occurred at lower temperatures. The DCP for the cooling rate of 0.03 °C/s was found to be 574°C (corresponding to 0.85 fraction solid) whereas the DCP for 0.43 °C/s was found to be 623°C (corresponding to 0.55 fraction solid).

scholarly journals Study of the Effect of Cooling Rate on Eutectic Modification in A356 Aluminium Alloys

2013 ◽  
Vol 765 ◽  
pp. 130-134 ◽  
Author(s):  
Deni Ferdian ◽  
Jacques Lacaze ◽  
Ibon Lizarralde ◽  
Andrea Niklas ◽  
Ana Isabel Fernandez-Calvo
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Cooling Rate ◽  
Melting Temperature ◽  
Aluminium Alloys ◽  
A356 Alloy ◽  
Cooling Curves ◽  
Eutectic Melting ◽  
Cooling Rates ◽  
Eutectic Modification

In this present work, an assessment of eutectic modification based on thermal analysis was performed on modified A356 alloy. The effect of various cooling rates which were achieved by means of casting samples with various moduli in sand and metallic moulds was investigated. Cooling curves recorded from thermocouples inserted in the centre of the samples showed characteristic undercooling and recalescence associated with (Al)-Si eutectic modification. The results showed that cooling rate has a role in observed modification level. Furthermore, differential thermal analysis was included to determine the eutectic melting temperature.

Effect of Cooling Rate on the Microstructure of Al-5.17Cu-2.63Si Cast Alloy

2013 ◽  
Vol 813 ◽  
pp. 157-160
Author(s):  
Guang Wei Zhao ◽  
Xi Cong Ye ◽  
Zeng Min Shi ◽  
Wen Jun Liu
Keyword(s):  
Cooling Rate ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Eutectic Phase ◽  
Cooling Curves ◽  
Cooling Rates ◽  
Dendrite Arm Spacing

The effect of cooling rate on the solicitation microstructure of a ternary cast Al-5.17Cu-2.63Si alloy is investigated. To create widely different cooling rates for the investigated alloy, the melts were cast into four molds made of different materials: aluminum, graphite, sand, and alumina-silicate-fiber felt (a thermal insulated material), respectively. The cooling curves for each mold specimen were simultaneously measured using calibrated K-type thermocouples, which are linked to a PC computer. The microstructures are characterized in terms of eutectic volume fraction and second dendrite arm spacing. The experiment result shows that increasing the cooling rate increases the amount of eutectic phase and decreases significantly the second dendrite arm spacing.

scholarly journals Determination of Eutectoid Transformation Temperatures in Ductile Cast Iron

2015 ◽  
Vol 15 (4) ◽  
pp. 51-54 ◽  
Author(s):  
A.W. Orłowicz ◽  
A. Trytek ◽  
M. Mróz ◽  
M. Tupaj
Keyword(s):  
Cast Iron ◽  
Cooling Rate ◽  
Ductile Cast Iron ◽  
Eutectoid Transformation ◽  
Heating Rates ◽  
Cooling Rates ◽  
Metallographic Examination ◽  
Transformation Temperatures ◽  
Rate Of Cooling

Abstract The paper proposes a methodology useful in verification of results of dilatometric tests aimed at determination of temperatures defining the start and the end of eutectoid transformation in the course of ductile cast iron cooling, based on quenching techniques and metallographic examination. For an industrial melt of ductile cast iron, the effect of the rate of cooling after austenitization at temperature 900°C carried out for 30 minutes on temperatures TAr1start and TAr1end was determined. The heating rates applied in the study were the same as the cooling rates and equaled 30, 60, 90, 150, and 300°C/h. It has been found that with increasing cooling rate, values of temperatures TAr1start and TAr1end decrease by several dozen degrees.

scholarly journals Bathroom brake circuits with vermicular graphite

2018 ◽  
pp. 40-49
Author(s):  
L Ivanova ◽  
E Kolotilo
Keyword(s):  
Rare Earth ◽  
Cast Iron ◽  
Cooling Rate ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Physical And Mechanical Properties ◽  
Cooling Rates ◽  
Highly Effective ◽  
Graphite Inclusions ◽  
The Rare Earth

The processes of structuring in cast iron of different chemical composition in the range of cooling rates of 0.5 ... 5.5 deg / s, which take place in the roll casting mould, are investigated. Scientifically based theoretical and experimental results were obtained, the set of which allowed to develop highly effective technologies of casting of rolling rolls from cast iron with vermicular graphite with increased operational characteristics. Optimum content of rare earth metal (REM) in roller cast iron with vermicular graphite at different cooling rates was experimentally established. In the low sulfur (up to 0,03%) cast iron, the rare earth metal residual (REMres) content is -0,065 ... 0,176 (for a cooling rate of 0,5 deg / s) and 0,01 ... 0,156% (for a cooling rate of 5,5 deg / s) . In the cast iron with high sulfur content (up to 0.10%), at the cooling rates studied, the intervals of concentrations of REMres have been experimentally established to provide the vermicular inclusions of graphite: at a cooling rate of 5.5 deg / c - 0.081-0.129%, and at a speed of 0.5 deg / s - 0.161 ... 0.190%. When modifying melts with a complex modifier based on magnesium KMg9, the Mg content at cooling rates of 5.5 and 0.5 deg / s should be within 0.022 ... 0.03 and 0.019 ... 0.03%, respectively, when treated with the complex KMg9 and FS30RZM30 in the cast iron it is necessary to have 0,0071 ... 0,015% Mg and 0,023 ... 0,025% REMres. With such content of modifiers, the best combinations of microstructure and physical and mechanical properties of castings are obtained. The areas of formation of vermicular graphite inclusions in roll cast irons were determined when processed with a complex modifier based on rare-earth metals and ferrotitanium: at a cooling rate of 5.5 degrees / s and a titanium content of 0.40 ... 0.42%, the concentration range of the rare-earth bridge for stable production of graphite inclusions of vermicular form has expanded and was 0.061 ... 0.169%, and at a cooling rate of 0.5 deg / s –0.129 ... 0.230%. The technological process of casting of bleached roller rolls has been improved due to the application of a highly effective complex modifier (ligature) of optimal composition for the modification of the base metal. The technology for the production of pig iron with vermicular graphite is developed and mastered at casting of rollers with the use of mixtures for modification consisting of two ligatures in the ratio of 1: 3.

Effect of Melt Cooling Rate on Microstructure of Sn - Bi and Sn - Pb Eutectic Alloys

2013 ◽  
Vol 856 ◽  
pp. 236-240 ◽  
Author(s):  
Olga Gusakova ◽  
Vasiliy Shepelevich ◽  
Lilia Scherbachenko
Keyword(s):  
Cooling Rate ◽  
Electron Backscatter Diffraction ◽  
Rapid Quenching ◽  
Grain Structure ◽  
Eutectic Alloys ◽  
Microcrystalline Structure ◽  
Cooling Rates ◽  
Mold Casting ◽  
Solidification Mechanism ◽  
Melt Cooling

The results of microstructure investigation of eutectic alloys Sn Bi and Sn Pb, obtained at cooling rates of the melt 10-2 K/s, 1 K/s and 105 K/s are represented. Various cooling rates are achieved by graphite mold casting and by ultra fast quenching from the melt. Microstructure and grain structure are investigated by scanning electron microscopy and the electron backscatter diffraction technique. It has found that the melt cooling rate increasing at rapid quenching leads to microcrystalline structure and to a change of the solidification mechanism. The reasons for the transition from lamellar to the microcrystalline structure are discussed.

The Effect of the Structure and the Heating and Cooling Rate on the Thermal Expansion of Grey Cast Iron

1984 ◽  
Vol 34 ◽  
Author(s):  
P. A. Sunnerkrantz ◽  
H. Fredriksson
Keyword(s):  
Thermal Expansion ◽  
Cast Iron ◽  
Temperature Dependence ◽  
Carbon Content ◽  
Cooling Rate ◽  
Grey Cast Iron ◽  
Cooling Rates ◽  
Heating And Cooling ◽  
Grey Cast ◽  
Increasing Temperature

ABSTRACTThe thermal expansion of grey cast iron was studied in six different alloys. The expansion was determined at two different heating and cooling rates. It was found that the expansion was influenced by the heating and cooling rates. The thermal expansion was larger than the thermal expansion in steel and the thermal expansion also increased with increasing temperature. The thermal expansion was theoretically analysed. The temperature dependence was accounted for, by considering the fact that the carbon content in austenite and ferrite increases with increasing temperature.

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