scholarly journals AUSTENITE – FERRITE TRANSFORMATION TEMPERATURES OF C MN AL HSLA STEEL

2021 ◽  
Vol 27 (4) ◽  
pp. 207-209
Author(s):  
Peter Prislupčák ◽  
Tibor Kvačkaj ◽  
Jana Bidulská ◽  
Pavol Záhumenský ◽  
Viera Homolová ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Transformation Temperature ◽  
Hsla Steel ◽  
Cooling Rates ◽  
Transformation Temperatures ◽  
Temperature Range ◽  
Dilatometric Method ◽  
Ferrite Transformation ◽  
Final Microstructure ◽  
Thermo Calc Software

The article is aimed to investigate a shift of transformation temperatures of C-Mn-Al HSLA steel with different cooling rates. The transformation temperatures from austenite to ferrite have been determined by dilatometry using thermal-mechanical simulator Gleeble 1500D. To define the start and finishing temperatures of the austenite-ferrite transformation intersectional method was used. Effect of cooling rate on transformation temperature has been evaluated for 0.17, 1, 5, 10, 15, 20, 25°C.s-1. There was found out that rising the cooling rate results in moving transformation temperature range to lower temperatures. The transformation temperatures have been also compared with temperatures calculated using equations of several authors. Some of them have considered cooling rates only. Cooling rates have effect on final microstructure. The effect has been evaluated by measuring hardness (HV10) relating the cooling rates from 0.17 to 25°C.s-1. Increasing cooling rates resulted in increase of hardness. Moreover, Thermo-Calc software was used to determine the Ae3 and Ae1 equilibrium temperatures. Equilibrium transformation temperatures Ae3-Ae1 were higher than experimentally measured by dilatometric method using Gleeble 1500D.

The effect of cooling rate on crystallization behavior and tensile properties of CF/PEEK composites

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Guangming Dai ◽  
Lihua Zhan ◽  
Chenglong Guan ◽  
Minghui Huang
Keyword(s):  
Cooling Rate ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Crystalline Polymer ◽  
Scanning Calorimetry ◽  
Nonisothermal Crystallization ◽  
Cooling Rates ◽  
Control Range ◽  
Temperature Range ◽  
Transverse Tensile

Abstract In this study, the differential scanning calorimetry (DSC) tests were performed to measure the nonisothermal crystallization behavior of carbon fiber reinforced polyether ether ketone (CF/PEEK) composites under different cooling rates. The characteristic parameters of crystallization were obtained, and the nonisothermal crystallization model was established. The crystallization temperature range of the material at different cooling rates was predicted by the model. The unidirectional laminates were fabricated at different cooling rates in the crystallization temperature range. The results showed that the crystallization temperature range shifted to a lower temperature with the increase of cooling rate, the established nonisothermal crystallization model was consistent with the DSC test results. It is feasible to shorten the cooling control range from the whole process to the crystallization range. The crystallinity and transverse tensile strength declined significantly with the increase of the cooling rate in the crystallization temperature range. The research results provided theoretical support for the selection of cooling conditions and temperature control range, which could be applied to the thermoforming process of semi-crystalline polymer matrixed composites to improve the manufacturing efficiency.

scholarly journals Influence of Cooling Rate on Nature and Morphology of Intercellular Precipitates in Si-Mo Ductile Irons

2018 ◽  
Vol 925 ◽  
pp. 231-238
Author(s):  
Mervat Youssef ◽  
Adel Nofal ◽  
Abdelhamid Hussein
Keyword(s):  
Cooling Rate ◽  
Lamellar Structure ◽  
Wide Spectrum ◽  
State Transformation ◽  
Solid State Transformation ◽  
Scanning Calorimetry ◽  
Cooling Rates ◽  
Eutectic Carbides ◽  
Thermo Calc Software ◽  
Scanning Electron

This work is designed to better understand the influence of cooling rate on the nature and morphology of intercellular precipitates in Silicon-Molybdenum ferritic ductile iron (SiMo). Plates of 3, 6, 9 mm thickness were cast in greensand and investment casting molds to give a wide spectrum of cooling rates. It was found that at higher cooling rates, the intercellular regions have a lamellar structure typical of pearlite. With decreasing cooling rates, the precipitate contains complex (Fe-Mo-Si) carbides of fine spheroidal or rod-like structure surrounding the eutectic carbides.Intensive Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) and Optical Microscopy (OM) investigations showed that the eutectic carbides are mainly (Fe, Mo, Si) C containing up to 48% Mo, whereas the fine precipitates contain lower Mo-contents. Both carbide types did not show to have a strict stoichometric composition. The solidification and solid-state transformation path was determined using both phase diagram calculated from Thermo-Calc software as well as Differential Scanning Calorimetry (DSC).

The transition temperature of the transition between grey and white tin

1958 ◽  
Vol 244 (1236) ◽  
pp. 101-109 ◽  
Keyword(s):  
Transition Temperature ◽  
Change Point ◽  
Transformation Temperature ◽  
Strain Energy ◽  
Transformation Temperatures ◽  
Temperature Range ◽  
Two Samples ◽  
Bismuth Antimony ◽  
Do So

Systematic experiments, using a sensitive dilatometric technique, have been carried out on the transformation temperatures of two samples of metallic tin and of a number of dilute tin-rich alloys. Vulcan tin(99·997% pure—majorimpurity iron) transforms in the temperature range 9·9 to 10·8°C, while Pass-S tin (also 99·997% pure—major impurity lead) transforms in the range 13·0 to 13·6°C. The transformation temperature observed for a given sample is higher the greater its ‘activity' (as measured by the time necessary to secure 40% transformation from grey tin to white tin at 30°C), suggesting that the observed change point is a function of the strain energy of the white tin formed. Additions of lead, bismuth, antimony and tellurium in the range 0·001 to 0·005 at. % raise the apparent transformation temperature of Vulcan tin, while similar quantities of zinc and aluminium have little effect. Substantial additions of zinc, aluminium, tellurium and germanium lower the observed transformation temperature of Vulcan tin. The results are discussed and it is suggested that those elements which raise the transformation temperature do so by increasing the degree to which strain energy may be retained in the white tin formed by the transformation.

Influence of Cooling Rate on Growth of Bacillus cereus from Spore Inocula in Cooked Rice, Beans, Pasta, and Combination Products Containing Meat or Poultry

2018 ◽  
Vol 81 (3) ◽  
pp. 430-436 ◽  
Author(s):  
Vijay K. Juneja ◽  
Tim B. Mohr ◽  
Meryl Silverman ◽  
O. Peter Snyder
Keyword(s):  
Bacillus Cereus ◽  
Cooling Rate ◽  
Egg Yolk ◽  
Spore Concentration ◽  
Cooling Rates ◽  
Cooling Period ◽  
Temperature Range ◽  
Cooked Rice

ABSTRACT The objective of this study was to assess the ability of Bacillus cereus spores to germinate and grow in order to determine a safe cooling rate for cooked rice, beans, and pasta, rice-chicken (4:1), rice-chicken-vegetables (3:1:1), rice-beef (4:1), and rice-beef-vegetables (3:1:1). Samples were inoculated with a cocktail of four strains of heat-shocked (80°C for 10 min) B. cereus spores (NCTC 11143, 935A/74, Brad 1, and Mac 1) to obtain a final spore concentration of approximately 2 log CFU/g. Thereafter, samples were exponentially cooled through the temperature range of 54.5 to 7.2°C in 6, 9, 12, 15, 18, and 21 h. At the end of the cooling period, samples were removed and plated on mannitol egg yolk polymyxin agar. The plates were incubated at 30°C for 24 h. The net B. cereus growth from spores in beans was <1 log after 9 h of cooling, but the pathogen grew faster in rice and pasta. In combination products, the net growth was as follows: 3.05, 3.89, and 4.91 log CFU/g in rice-chicken; 3.49, 4.28, and 4.96 log CFU/g in rice-beef; 3.50, 4.20, and 5.32 CFU/g in rice–chicken–mixed vegetables; and 3.68, 4.44, and 5.25 CFU/g in rice–beef–mixed vegetables after 15, 18, and 21 h of cooling, respectively. This study suggests safe cooling rates for cooling cooked rice, beans, pasta, rice-chicken, rice-chicken-vegetables, rice-beef, and rice-beef-vegetables to guard against the hazards associated with B. cereus.

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 Microstructure and Hardness Evolution of Al8Zn7Ni3Mg Alloy after Casting at very Different Cooling Rates

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 762 ◽  
Author(s):  
Pavel Shurkin ◽  
Torgom Akopyan ◽  
Nataliya Korotkova ◽  
Alexey Prosviryakov ◽  
Andrey Bazlov ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Melt Spinning ◽  
Nickel Content ◽  
Microstructural Analysis ◽  
Aluminum Matrix ◽  
High Strength ◽  
Eutectic Type ◽  
Cooling Rates ◽  
Aging Response ◽  
Thermo Calc Software

In this study, we combined both a high strength Al-8%Zn-3%Mg aluminum matrix and a reinforcing contribution of Al3Ni intermetallics in Al8Zn7Ni3Mg hypereutectic alloy with a tuned microstructure via a variation of cooling rates from 0.1 K/s to 2.3 × 105 K/s. Using the Thermo-Calc software, we analyzed the effect of nickel content on the phase equilibria during solidification and found out that 7%Ni provides a formation of equal fractions of primary (6.5 vol.%) and eutectic (6.3 vol.%) crystals of the Al3Ni phase. Using microstructural analysis, a refinement of intermetallics with an increase in cooling rate was observed. It is remarkable that the structure after solidification at ~103 K/s across 1 mm flake casting consists of a quasi-eutectic with 1.5 μm Al3Ni fibers, while an increase in the cooling rate to ~105 K/s after melt spinning leads to the formation of 50 nm equiaxed Al3Ni particles. Under these conditions, the alloy showed an aging response at 200 °C, resulting in hardness of 200 HV and 220 HV, respectively. After 470 °C annealing, the fibers in the 1 mm sample evolved to needles. However, in melt-spun ribbons, the particles were kept globular and small-sized. Overall, the results may greatly contribute to the development of new eutectic type composites for rapid solidification methods.

Non-isothermal crystallization behavior of spinel crystals in FeO-SiO2-TiO2-V2O3-Cr2O3 slag

2018 ◽  
Vol 116 (1) ◽  
pp. 110
Author(s):  
Lixiong Shao ◽  
Jiang Diao ◽  
Wang Zhou ◽  
Tao Zhang ◽  
Bing Xie
Keyword(s):  
Cooling Rate ◽  
Crystallization Behavior ◽  
Crystal Size ◽  
Growth Mechanisms ◽  
Vanadium Slag ◽  
Growth Behaviour ◽  
Temperature Range ◽  
Chromium Spinel ◽  
Mean Diameter ◽  
The Mean

The growth behaviour of spinel crystals in vanadium slag with high Cr2O3 content was investigated and clarified by statistical analyses based on the Crystal Size Distribution (CSD) theory. The results indicate that low cooling rate and Cr2O3 content benefit the growth of spinel crystals. The chromium spinel crystals firstly precipitated and then acted as the heterogeneous nuclei of vanadium and titanium spinel crystals. The growth mechanisms of the spinel crystals at the cooling rate of 5 K/min consist two regimes: firstly, nucleation control in the temperature range of 1873 to 1773 K, in which the shapes of CSD curves are asymptotic; secondly, surface and supply control within the temperature range of 1773 to 1473 K, in which the shapes of CSD curves are lognormal. The mean diameter of spinel crystals increases from 3.97 to 52.21 µm with the decrease of temperature from 1873 to 1473 K.

scholarly journals A Comparative Study of Acicular Ferrite Transformation Behavior between Surface and Interior in a Low C–Mn Steel by HT-LSCM

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 699
Author(s):  
Xiaojin Liu ◽  
Guo Yuan ◽  
Raja. Devesh Kumar Misra ◽  
Guodong Wang
Keyword(s):  
Grain Boundaries ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Laser Scanning ◽  
Sample Surface ◽  
Surface Microstructure ◽  
In Situ Observation ◽  
Low Carbon ◽  
Transformation Behavior ◽  
Ferrite Transformation

In this study, the acicular ferrite transformation behavior of a Ti–Ca deoxidized low carbon steel was studied using a high-temperature laser scanning confocal microscopy (HT-LSCM). The in situ observation of the transformation behavior on the sample surface with different cooling rates was achieved by HT-LSCM. The microstructure between the surface and interior of the HT-LSCM sample was compared. The results showed that Ti–Ca oxide particles were effective sites for acicular ferrite (AF) nucleation. The start transformation temperature at grain boundaries and intragranular particles decreased with an increase in cooling rate, but the AF nucleation rate increased and the surface microstructure was more interlocked. The sample surface microstructure obtained at 3 °C/s was dominated by ferrite side plates, while the ferrite nucleating sites transferred from grain boundaries to intragranular particles when the cooling rate was 15 °C/s. Moreover, it was interesting that the microstructure and microhardness of the sample surface and interior were different. The AF dominating microstructure, obtained in the sample interior, was much finer than the sample surface, and the microhardness of the sample surface was much lower than the sample interior. The combined factors led to a coarse size of AF on the sample surface. AF formed at a higher temperature resulted in the coarse size. The available particles for AF nucleation on the sample surface were quite limited, such that hard impingement between AF plates was much weaker than that in the sample interior. In addition, the transformation stress in austenite on the sample surface could be largely released, which contributed to a coarser AF plate size. The coarse grain size, low dislocation concentration and low carbon content led to lower hardness on the sample surface.

Intercritical Interrupted Jominy Test

2007 ◽  
Vol 537-538 ◽  
pp. 549-554
Author(s):  
Mihály Réger ◽  
Balázs Verő ◽  
Zsolt Csepeli ◽  
Péter Pinke
Keyword(s):  
Cooling Rate ◽  
Treatment Process ◽  
Intercritical Annealing ◽  
Technological Parameters ◽  
Post Heat Treatment ◽  
Quenching Process ◽  
Final Microstructure ◽  
Jominy Test ◽  
The Individual ◽  
Quench Test

The final microstructure of DP and TRIP assisted steels can evolve after hot working (hot rolling) or during post heat treatment process. In the formation of the final structure a number of different technological parameters have important role, e.g. finishing temperature of rolling, cooling rates, temperature of intercritical annealing, etc. As a result of the individual factors and their combinations a lot of production technology routes are feasible. The effect of the different combinations of these technological parameters on the microstructure can be mapped by a special Jominy end-quench test (so called intercritical Jominy end-quench test) described in this paper. Unlike the traditional Jominy test, in this case there is a partial austenizing between A1 and A3 temperatures which results in a given amount of ferrite in the microstructure before quenching. The amount of ferrite depends on the temperature. In some cases the quenching process was interrupted for a given period of time in order to model the cooling process on the run-out table. During cooling each point of the Jominy specimen has a different cooling rate, so the effect of cooling rate on the microstructure can be evaluated along the length of the specimen.

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