Artigos de revistas: "Carbon segregation"

1

Tang, Hai Yan, Hong Bin Wang, Hai Shun Li, Jing She Li e Qing Guo Wang. "Researches on the Behavior of Carbon and Sulfur Segregations of 82B Billet". Advanced Materials Research 399-401 (novembro de 2011): 206–10. http://dx.doi.org/10.4028/www.scientific.net/amr.399-401.206.

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The behavior of carbon and sulfur segregations of 82B hard wire steel produced under different continuous casting conditions has been systematically studied by the combination of field trial and laboratory analysis. The results showed three factors such as superheat degree, casting speed and F-EMS which influenced the segregation of billet worked differently with the variations of inner positions of the billet and segregation elements. For the central segregations of carbon and sulfur, the dominant factor was casting speed. Under high casting speed, proper increase of secondary cooling intensity could effectively decrease carbon and sulfur segregations of billet, especially for the central position of billet. The hydraulic simulation of the tundish showed the optimal casting speed should be 1.8m/min.

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Oehme, M., M. Bauer, C. P. Parry, G. Eifler e E. Kasper. "Carbon segregation in silicon". Thin Solid Films 380, n.º 1-2 (dezembro de 2000): 75–77. http://dx.doi.org/10.1016/s0040-6090(00)01533-9.

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3

Chen, Jing Hu, e Xiao Hua Jie. "Study of Centerline Segregation in Alloy Tool Steel on CSP Technology". Advanced Materials Research 197-198 (fevereiro de 2011): 1744–48. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.1744.

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After studying the slab of the CSP, the composition segregation and the finished products, we drew the conclusion that the low magnification of CSP thin slab is denser, columnar grain more developed; Loose and segregation exist while the segregation is smaller than traditional one. From the surface to the center, obvious carbon segregation exists: nearby the center is negative segregation and in the center is positive segregation. With the increase of carbon content, carbon segregation also increases. The carbon content of tundish is different from that of rolled steel coil --namely, the carbon content of the rolled coil is significantly lower.

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4

Ewels, C. P., D. Erbahar, Ph Wagner, X. Rocquefelte, R. Arenal, P. Pochet, M. Rayson, M. Scardamaglia, C. Bittencourt e P. Briddon. "Nitrogen segregation in nanocarbons". Faraday Discuss. 173 (2014): 215–32. http://dx.doi.org/10.1039/c4fd00111g.

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We explore the behaviour of nitrogen doping in carbon nanomaterials, notably graphene, nanotubes, and carbon thin films. This is initially via a brief review of the literature, followed by a series of atomistic density functional calculations. We show that at low concentrations, substitutional nitrogen doping in the sp²-C graphenic basal plane is favoured, however once the nitrogen concentration reaches a critical threshold there is a transition towards the formation of the more thermodynamically-favoured nitrogen terminated ‘zigzag’ type edges. These can occur either via formation of finite patches (polycyclic aromatic azacarbons), strips of sp² carbon with zigzag nitrogen edges, or internal nitrogen-terminated hole edges within graphenic planes. This transition to edge formation is especially favoured when the nitrogen can be partially functionalised with, e.g. hydrogen. By comparison with available literature results, notably from electron energy loss spectroscopy and X-ray spectroscopy, the current results suggest that much of the nitrogen believed to be incorporated into carbon nanoobjects is instead likely to be present terminating the edges of carbonaceous impurities attached to nanoobject's surface. By comparison to nitrogen-doped tetrahedrally amorphous carbon, we suggest that this transition at around 10–20% nitrogen concentration and above towards sp² coordination via internal nitrogen-terminated edge formation may be a general property of nitrogen-doped carbon materials.

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5

Liu, Daiwei, Guifang Zhang, Jianhua Zeng e Xin Xie. "Numerical Simulation of Segregation in Slabs under Different Secondary Cooling Electromagnetic Stirring Modes". Materials 17, n.º 11 (3 de junho de 2024): 2721. http://dx.doi.org/10.3390/ma17112721.

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Secondary cooling electromagnetic stirring (S-EMS) significantly impacts the internal quality of continuous casting slabs. In order to investigate the effects of S-EMS modes on segregation in slabs, a three-dimensional numerical model of the full-scale flow field, solidification, and mass transfer was established. A comparative analysis was conducted between continuous electromagnetic stirring and alternate stirring modes regarding their impacts on steel flow, solidification, and carbon segregation. The results indicated that adopting the alternate stirring mode was more advantageous for achieving uniform flow fields and reducing the disparity in solidification endpoints, thus mitigating carbon segregation. Specifically, the central carbon segregation index under continuous stirring at 320 A was 1.236, with an average of 1.247, while under alternate stirring, the central carbon segregation index decreased to 1.222 with an average of 1.227.

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6

Li, Pengchao, Guifang Zhang, Peng Yan, Nan Tian e Zhenhua Feng. "Numerical and Experimental Study on Carbon Segregation in Shaped Billet of Medium Carbon Steel with Combined Electromagnetic Stirring". Materials 16, n.º 23 (30 de novembro de 2023): 7464. http://dx.doi.org/10.3390/ma16237464.

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Carbon segregation is the major and classical internal defect in the continuous casting process of carbon steel. Based on the combined electromagnetic stirring equipment for new billet in a steel plant, China, the influence of combined electromagnetic stirring (M-EMS + F-EMS) on the carbon segregation of 300 mm × 340 mm special-shaped billet was studied via numerical simulation and on-site industrialization tests. The Lorentz force and carbon solute distribution were simulated under different EMS parameters. The formation mechanism of the carbon segregation of medium carbon steel with different combined electromagnetic stirring processes was analyzed. The results show that: (1) with the combined action of “solute flushing” effect and gravity, the carbon concentration in the loose side of the medium carbon steel casting billet is gradually lower than the fixed side, while the carbon concentration on the fixed side gradually accumulates more; and (2) under the action of combined electromagnetic stirring, the segregation index of casting billet could be controlled to remain between 0.96–1.05 and shows an increasing change in solidification from the skin to the center. When the current and frequency of M-EMS are 250 A and 2.0 Hz and the F-EMS are 180 A and 8.0 Hz, the carbon segregation defects in the special-shaped (300 mm × 340 mm) casting billet can be significantly improved.

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Potekhina, N. D., N. R. Gall’, E. V. Rut’kov e A. Ya Tontegode. "Carbon segregation on a tungsten surface". Physics of the Solid State 45, n.º 4 (abril de 2003): 782–87. http://dx.doi.org/10.1134/1.1569021.

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Janthon, Patanachai, Francesc Viñes, Jakkapan Sirijaraensre, Jumras Limtrakul e Francesc Illas. "Carbon dissolution and segregation in platinum". Catalysis Science & Technology 7, n.º 4 (2017): 807–16. http://dx.doi.org/10.1039/c6cy02253g.

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Density functional studies at show the feasibility of C subsurface incorporation in Platinum occupying tetrahedral sites. A comparative with Ni and Pd highlights that surface relaxation is critical in C dissolution, specially at low-coordinated sites of Pt nanoparticles. Results explain phenomena such as C dissolution and segregation to form graphene from below, and may serve to tune the Pt surface chemical reactivity.

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Mizushima, Ichiro, Eiji Kamiya, Norihisa Arai, Masahisa Sonoda, Masahiko Yoshiki, Shin-ichi Takagi, Mikio Wakamiya et al. "Diffusion and Segregation of Carbon inSiO2Films". Japanese Journal of Applied Physics 36, Part 1, No. 3B (30 de março de 1997): 1465–68. http://dx.doi.org/10.1143/jjap.36.1465.

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10

Alaoua, D., A. Larere, D. Roptin e G. Saindrenan. "Surface segregation in low carbon steels". Materials Science and Engineering: A 174, n.º 2 (fevereiro de 1994): 187–92. http://dx.doi.org/10.1016/0921-5093(94)91087-1.

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11

Dou, Kun, Zhenguo Yang, Qing Liu, Yunhua Huang e Hongbiao Dong. "Influence of Secondary Cooling Mode on Solidification Structure and Macro-segregation Behavior for High-carbon Continuous Casting Bloom". High Temperature Materials and Processes 36, n.º 7 (26 de julho de 2017): 741–53. http://dx.doi.org/10.1515/htmp-2016-0022.

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AbstractA cellular automaton–finite element coupling model for high-carbon continuously cast bloom of GCr15 steel is established to simulate the solidification structure and to investigate the influence of different secondary cooling modes on characteristic parameters such as equiaxed crystal ratio, grain size and secondary dendrite arm spacing, in which the effect of phase transformation and electromagnetic stirring is taken into consideration. On this basis, evolution of carbon macro-segregation for GCr15 steel bloom is researched correspondingly via industrial tests. Based on above analysis, the relationship among secondary cooling modes, characteristic parameters for solidification structure as well as carbon macro-segregation is illustrated to obtain optimum secondary cooling strategy and alleviate carbon macro-segregation degree for GCr15 steel bloom in continuous casting process. The evaluating method for element macro-segregation is applicable in various steel types.

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12

Komarov, O. S., O. V. Rozenberg, N. I. Urbanovich e K. E. Baranowski. "INFLUENCE OF THE MACROSTRUCTURE ON SEGREGATION OF THE STEEL INGOT". Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), n.º 1 (14 de março de 2017): 45–49. http://dx.doi.org/10.21122/1683-6065-2017-1-45-49.

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A theoretical analysis of the influence of carbon content in the steel and nature of macrostructure on segregation of impurities in the crystallization process were made. It is shown that increase of carbon content and transgranular macrostructure creation degree of segregation is being increased. A comparison of sulfur segregation in the ingot with equiaxial and transgranular structure was carried out and the theoretical points were confirmed.

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13

Malherbe, Johan B., Opeyemi S. Odutemowo, Chris C. Theron e Elke Wendler. "Diffusion of strontium implanted in glassy carbon". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 477, n.º 2250 (junho de 2021): 20200797. http://dx.doi.org/10.1098/rspa.2020.0797.

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Glassy carbon has properties making it attractive as a containment material for radioactive waste. In this study, the diffusivity of the radiological important fission product, strontium, is measured. Two hundred kiloelectronvolt strontium ions were implanted at room temperature. The implanted samples were either annealed isochronally for 1 h up to 900°C or by increasing the temperature linearly up to 648°C. The Sr profiles were determined by Rutherford backscattering spectrometry (RBS). The isochronally annealed samples showed Fickian diffusion at 300°C ( D = 6.7 × 10 −19 m 2 s −1 ) with segregation occurring at the higher temperatures. Raman spectroscopy indicated a link between damage annealing and the onset of segregation. During increasing temperature, the system is dynamic with diffusion taking place. An equation to determine diffusion coefficients for ramped heating was derived. Fickian diffusion occurred with an activation energy of 1.97 eV for 414–454°C, and from 458 to 558°C, it was 0.184 eV. At higher temperatures, a segregation of the strontium towards the surface was observed. A calculation of the heat of segregation of Sr in carbon supports this segregation. The results show that the in situ RBS measurements with a linear increase in temperature give additional information compared with the conventional isochronal annealing.

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14

Lerchbacher, Christoph, Silvia Zinner e Harald Leitner. "Carbon Distribution and the Influence on the Tempering Behaviour in a Hot-Work Tool Steel Aisi H11". Advanced Materials Research 409 (novembro de 2011): 702–6. http://dx.doi.org/10.4028/www.scientific.net/amr.409.702.

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The microstructure of the common hot-work tool steel AISI H11 has been characterized by atom probe tomography with the focus on the carbon distribution after the hardening treatment and in the early stages of tempering. The carbon distribution shows significant differences within the probed volumes, regions differently affected by carbon segregation can be observed in some specimens. In all samples pronounced carbon segregation to dislocations and cluster formation is observed. Through all hardened samples no segregation of any substitutional elements has taken place. Heating to 500°C does not significantly change the elemental distribution. Carbon enriched interlath austenite films with peak carbon levels of 6 to 9 at% show a thickness increase with increasing λ. These films and the pre-existing carbon clusters have been found to be nucleation sites for carbide formation during heating to 610°C.

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15

Li, Pengchao, Guifang Zhang, Peng Yan, Peipei Zhang, Nan Tian e Zhenhua Feng. "Numerical and Experimental Study on Carbon Segregation in Square Billet Continuous Casting with M-EMS". Materials 16, n.º 16 (9 de agosto de 2023): 5531. http://dx.doi.org/10.3390/ma16165531.

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Electromagnetic stirring (M-EMS) has been extensively applied in continuous casting production to reduce the quality defects of casting billets. To investigate the effect of continuous casting electromagnetic stirring on billet segregation, a 3D multi-physics coupling model was established to simulate the internal heat, momentum, and solute transfer behavior, to identify the effect of M-EMS on the carbon segregation of a continuous casting square billet of 200 mm × 200 mm. The results show that M-EMS can move the high-temperature zone upward, which is favorable for the rapid solidification of the billet, and can promote the rotational flow of the molten steel in the horizontal direction. When the electromagnetic stirring current is varied in the range of 0–500 A, the degree of carbon segregation first decreases and then increases, with the best control of segregation at 300 A. In the frequency range of 3–5 Hz, the degree of carbon segregation degree increases with frequency. Meanwhile, the simulation and experimental results show that 3 Hz + 300 A is the best electromagnetic stirring parameter for improving the carbon segregation of casting billets with a size of 200 mm × 200 mm. So, a reasonable choice of the M-EMS parameters is crucial for the quality of the billet.

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16

Yu, Zhu Huan, e Jun Feng Qiang. "Microsegregation Behavior of Single Crystal Superalloy". Advanced Materials Research 983 (junho de 2014): 121–26. http://dx.doi.org/10.4028/www.scientific.net/amr.983.121.

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The major advancements in some mechanical properties of single crystal superalloys can be attributed to the carbon addition. The present study investigated the effect of carbon addition levels on the microsegregation behavior of single crystal superalloys. Quantitatative partitioning results indicated that typical single crystal superalloy segregation behavior for some elements such as W, Ni, Co, are all towards the dendrite core regions, while for elements of Al, Mo, Ta, Ti, Cr, partition towards the interdendrite regions. For all the alloys studied, the baseline alloy showed the most severe segregation degree, while the no carbon alloy the slightest. Furthermore, the segregation behavior of Ti and Ta were affected by the carbon additions, and that of W was greatly affected by the carbon levels.

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17

Kim, Kwan Ho, e Chul Min Bae. "Study on the Soaking Condition of High Carbon Chromium Bearing Steels". Materials Science Forum 783-786 (maio de 2014): 825–30. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.825.

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In order to seek the proper soaking condition of a high carbon chromium bearing steel, 100Cr6, a new approach was investigated considering the diffusion of chromium atoms. Although it is true that the large carbides are bigger with the worse degree of center segregation of continuously cast blooms, the size of center segregation band in blooms has a more accurate relationship with the degree of center segregation. Therefore, on behalf of the large carbide size in the conventional method, the size of center segregation band in continuously cast blooms of the steel has been used for the new approach. As a result, the center segregation and large carbides in them were removed completely by the new soaking condition.

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Li, Na, Jun Qiao, Junwei Zhang, Minghong Sha e Shengli Li. "Phosphorus Segregation in Meta-Rapidly Solidified Carbon Steels". High Temperature Materials and Processes 36, n.º 9 (26 de setembro de 2017): 905–12. http://dx.doi.org/10.1515/htmp-2016-0066.

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AbstractTwin-roll strip casters for near-net-shape manufacture of steels have received increased attention in the steel industry. Although negative segregation of phosphorus occurred in twin-roll strip casting (TRSC) steels in our prior work, its mechanism is still unclear. In this work, V-shaped molds were designed and used to simulate a meta-rapid solidification process without roll separating force during twin roll casting of carbon steels. Experimental results show that no obvious phosphorus segregation exist in the V-shaped mold casting (VMC) steels. By comparing TRSC and the VMC, it is proposed that the negative phosphorus segregation during TRSC results from phosphorus redistribution driven by recirculating and vortex flow in the molten pool. Meanwhile, solute atoms near the advancing interface are overtaken and incorporated into the solid because of the high solidification speed. The high rolling force could promote the negative segregation of alloying elements in TRSC.

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Li, Na, Jun Wei Zhang e Lu Lu Zhai. "Segregation of C, P and Mn in Rapid Solidified Carbon Steels". Advanced Materials Research 189-193 (fevereiro de 2011): 3857–61. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3857.

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The quality and properties of steels may be affected due to the segregation of the alloying elements, even though the properties of steels can be improved by adding appropriate amount of alloying elements. Rapid solidification was regarded to be an effective method to reduce or eliminate the segregation of alloying elements. While the segregation of C, P and Mn was also observed in rapid solidified (in silicone oil) droplet carbon steels in this paper. The microstructures of rapid solidified droplets were rather fine. When the P content was less than about 0.09% (in mass) in low carbon steels, P did not show obvious segregation in rapid solidified droplet samples; when the P content raised up to about 0.5% in the samples, both P and Mn showed center segregation even though the content of Mn kept unchanged. So the alloying elements can segregate and even effect the distribution of other elements in rapid solidified steel samples. When the C content increased, the segregation of C was observed in high-C samples, while the segregation tendency is opposite to that of P in high-P samples. For all the droplet samples, the micro-hardness of high-P samples was also much higher than those samples with less P content.

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20

Cabal, Ciro, Ricardo Martínez-García, Aurora de Castro Aguilar, Fernando Valladares e Stephen W. Pacala. "The exploitative segregation of plant roots". Science 370, n.º 6521 (3 de dezembro de 2020): 1197–99. http://dx.doi.org/10.1126/science.aba9877.

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Plant roots determine carbon uptake, survivorship, and agricultural yield and represent a large proportion of the world’s vegetation carbon pool. Study of belowground competition, unlike aboveground shoot competition, is hampered by our inability to observe roots. We developed a consumer-resource model based in game theory that predicts the root density spatial distribution of individual plants and tested the model predictions in a greenhouse experiment. Plants in the experiment reacted to neighbors as predicted by the model’s evolutionary stable equilibrium, by both overinvesting in nearby roots and reducing their root foraging range. We thereby provide a theoretical foundation for belowground allocation of carbon by vegetation that reconciles seemingly contradictory experimental results such as root segregation and the tragedy of the commons in plant roots.

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21

Alaoua, D., A. Larere, Sylvie Lartigue-Korinek e L. Priester. "Interfacial Segregation in Ultra-Low Carbon Steels". Materials Science Forum 126-128 (janeiro de 1993): 185–88. http://dx.doi.org/10.4028/www.scientific.net/msf.126-128.185.

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Bowker, Michael, Jonathan Counsell, Kareem El-Abiary, Lee Gilbert, Chris Morgan, Sankaranarayanan Nagarajan e Chinnakonda S. Gopinath. "Carbon Dissolution and Segregation in Pd(110)". Journal of Physical Chemistry C 114, n.º 11 (março de 2010): 5060–67. http://dx.doi.org/10.1021/jp9108046.

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23

Arabczyk, W., e U. Narkiewicz. "Segregation of carbon in iron and molybdenum". Surface Science 352-354 (maio de 1996): 223–27. http://dx.doi.org/10.1016/0039-6028(95)01137-4.

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24

Réger, Mihály, Balázs Verő, Ibolya Kardos, Fábián Enikő-Réka e György Kaptay. "Diffusion of Carbon in the Centerline Region of Continuous Cast Slabs". Materials Science Forum 659 (setembro de 2010): 441–46. http://dx.doi.org/10.4028/www.scientific.net/msf.659.441.

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The paper deals with the stability of centerline inhomogenity of continuously cast slabs and hot rolled products. The centerline segregation is a disadvantageous failure of slabs which can affect the quality properties of the final products. During hot rolling of the slabs the centerline segregation pattern will become thin and stretched and it can also be detected in the middle part of heavy plates and coils. It is a common experience that the centerline segregation of heavy plates can not be easily decreased by post heat treatment. The pattern of the centerline segregation was modeled physically by preparing a sandwich structure of steel plates with different levels of carbon and alloying elements. Homogenization experiments were performed and the samples were examined metallographically. Diffusional calculations proved the governing role of carbon activity which is influenced by the distribution of alloying elements.

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Wang, Jianjun, Xiaofang Shi, Lizhong Chang, Haijun Wang e Lipeng Meng. "Effect of Ultrasonic Treatment on the Solidification Microstructure of GCr15 Bearing Steel". High Temperature Materials and Processes 35, n.º 2 (1 de fevereiro de 2016): 161–68. http://dx.doi.org/10.1515/htmp-2014-0148.

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AbstractUltrasonic treatment with various powers is introduced to liquid steel from the side wall of a mold during GCr15 steel solidification, and the effect of ultrasonic on the microstructure and properties of GCr15 steel is investigated. Results show that the columnar grains in the GCr15 steel are coarse and that the microstructure is inhomogeneous when ultrasonic is not applied on the liquid steel. A suitable power ultrasonic leads to the appearance of a large number of equiaxed grains and increases the uniformity of the microstructure. The segregation of alloy elements gradually decreases as the power increases from 0 W to 500 W. The maximum segregations of carbon and silicon decrease from 2.541 to 1.129 and 2.861 to 1.196, respectively. Given a power of 500 W, the statistical segregations of carbon and silicon decrease from 0.0964 to 0.0693 and 0.1152 to 0.1075, respectively. A further increase in ultrasonic power is not conducive for improving the element segregation. Ultrasonic treatment can remarkably refine the size of carbide and increase the uniformity of its distribution. When the powers are 0 W, 300 W, 500 W, 700 W, and 1,000 W, the average sizes of carbide are 14.63 μm, 2.96 μm, 3.05 μm, 3.72 μm, and 7.83 μm, respectively. The tensile strength, yield strength, and ductility and reduction of the area of the GCr15 bearing steel are correspondingly improved to varying degrees.

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Cui, Yan, Ai Min Ji, Yun Li Feng, Rui Zhen Wang e Qi Long Yong. "Effect of Grain Size and Annealing Condition on Grain Boundary Segregation of Carbon Atoms in ULC Steel". Applied Mechanics and Materials 302 (fevereiro de 2013): 286–91. http://dx.doi.org/10.4028/www.scientific.net/amm.302.286.

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The grain boundary segregation of carbon atoms is influenced by grain size and annealing condition. Increasing grain size and improving the final cooling ( ＜400 oC) rate can improve the bake hardening property, due to the decreasing of carbon segregation at grain boundaries. Cooling rates have a great effect on bake hardening property of ULC steel with smaller grains

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Kaur, Harpreet, e Paramjeet Kaur. "Factors Determining Household Waste Segregation Behaviour: An Indian Case Study". International Journal of Experimental Research and Review 41, Spl Vol (30 de julho de 2024): 83–95. http://dx.doi.org/10.52756/ijerr.2024.v41spl.007.

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Waste represents used things or materials that are no longer required or wanted. These articles are cast off as they have stopped working or because they have ceased to be of value. Human settlements inevitably generate waste. According to UNEP's Global Waste Management Outlook 2024, the quantity of waste being generated is growing each year due to augmented economic growth accompanied with untenable consumption and production practices. In fact, global municipal solid waste (MSW) generation per year is projected to grow from 2.1 billion tonnes in 2020 to 2.7 billion tonnes in 2030 and further to 3.2 and 3.8 billion tonnes in 2040 and 2050 respectively. According to the World Bank, more than a third of waste generated globally is not managed in an environmentally sound manner and emissions related to solid waste are likely to increase to 2.6 billion tons of carbon dioxide equivalent by 2050. The present study based in Delhi with a sample of 708 households aims to understand the factors influencing the adoption of the “practice of waste segregation” by households. From our SEM and Path analysis we conclude that environmental awareness, knowledge about waste segregation and the perception about actual task of waste segregation have a significant impact on the practice of waste segregation. Environmental awareness has the largest impact followed by knowledge about how to undertake the task of waste segregation. In the light of our results, it is important and imperative to create awareness about the negative environmental impact of not segregating waste as well as demystifying the actual task of practising waste segregation.

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Zhang, Mengyun, Yanping Bao, Lihua Zhao e Xin Li. "Improvement of carbon segregation in cast bloom and heredity in hot-rolled bar". Metallurgical Research & Technology 118, n.º 6 (2021): 610. http://dx.doi.org/10.1051/metal/2021072.

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In this study, the effect of mechanical soft reduction on carbon segregation in the continuous casting of 300 × 400 mm 42CrMo alloy structural steel blooms was comparatively investigated by adjusting the casting speed, which was systematically optimized through numerical simulation. When the casting speed is 0.60 m · min−1, during the soft reduction process, the central solidification structure of the bloom becomes dense, and carbon segregation is improved. Moreover, the distribution of carbon in the samples before and after rolling was analyzed. Combined with the soft reduction process, the uniformity of carbon across the cross section of the bloom /bar distinctly improved for casting speeds of 0.50 m · min−1, 0.55 m · min−1 and 0.60 m · min−1, this was predominantly reflected in the core areas. The effective segregation length proportion of the bloom and rolled bar is approximately 40%. This phenomenon fully verifies the heredity characteristics of the elements in the rolling process.

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Wang, Yadong, e Lifeng Zhang. "Effect of the current intensity and positions of mold electromagnetic stirring on the macrosegregation in the full-length curved continuous casting bloom". Metallurgical Research & Technology 120, n.º 5 (2023): 502. http://dx.doi.org/10.1051/metal/2023062.

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A full-length curved continuous casting bloom mathematical model, coupling flow field, heat transfer, solidification, and electromagnetic stirring, was established to investigate the effect of the current intensity and positions of mold electromagnetic stirring (M-EMS) on the macrosegregation. M-EMS can optimize the negative segregation in the subsurface of the bloom and the positive segregation in the bloom center. With the current intensity of M-EMS increasing from 0 A to 350 A, the minimum carbon content in the subsurface of the bloom was 0.165%, 0.169%, 0.176%, and 0.182%. The carbon content in the bloom center was 0.246%, 0.243%, 0.241%, and 0.238%. The installation position of M-EMS can change the flow field and then affected the macrosegregation. When the positions of M-EMS were 0.77 m, 0.57 m, and 0.37 m beneath the meniscus, the minimum carbon content of negative segregation in the subsurface of the bloom was 0.174%, 0.182%, and 0.175%. The carbon content in the bloom center was 0.245%, 0.238%, and 0.235% respectively.

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An, Hanghang, Yan Ping Bao, Min Wang, Quan Yang, Xiang Hong Wang e Yan Yin Dang. "High-efficiency continuous casting of GCr15 bearing steel bloom based on cooperative control technique of complex electromagnetic stirring and soft reduction". Metallurgical Research & Technology 116, n.º 6 (2019): 621. http://dx.doi.org/10.1051/metal/2019051.

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GCr15 bearing steel exhibits comparatively serious center macro-segregation in the continuous casting of bloom with the increase of casting speed. In the present work, the influence of complex electromagnetic stirring (M + F-EMS) and mechanical soft reduction (MSR) on the center macro-segregation in the continuous casting of 220 × 260 mm blooms of GCr15 bearing steel have been comparatively investigated to increase casting speed in order to ensure a good internal quality. Based on numerical simulation and experiments, M + F-EMS and MSR have been comprehensively evaluated and compared by combination of industrial trials. The results show that center carbon segregation first decreases and then increases with the increase of casting speed in both processes without optimization. For M + F-EMS process, when casting speed increases from 0.75 to 0.85 m · min−1, the average degree of center carbon segregation decreases from 1.2 ∼ 1.26 to 1.18 ∼ 1.25 by asymmetrical optimization; with regard to combination of M + F-EMS and MSR process, when casting speed increases from 0.75 to 0.9 m · min−1, the average degree of center carbon segregation decreases from 1.2 ∼ 1.26 to 1.08 ∼ 1.1 and the solute element distribution becomes homogeneous by optimization. In comparison, significant reduction of the center macro-segregation with the increase of casting speed can be achieved for combination of M + F-EMS and MSR process, however, it is infeasible for M + F-EMS process in the present technology situation.

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Réger, Mihály, Balázs Verő, Ibolya Kardos e Péter Varga. "The Effect of Alloying Elements on the Stability of Centerline Segregation". Defect and Diffusion Forum 297-301 (abril de 2010): 148–53. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.148.

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The paper deals with the stability of centerline inhomogenity of continuously cast slabs and hot rolled products. The centerline segregation is a disadvantageous failure of slabs which can affect the quality properties of the final products. During hot rolling of slabs the centerline segregation pattern will become thin and stretch and it can also be detected in the middle part of heavy plates and coils. It is a common experience that the centerline segregation of heavy plates can not be easily decreased by post heat treatment. The pattern of the centerline segregation was modeled physically by preparing a sandwich structure of steel plates with different levels of carbon and alloying elements. Homogenization experiments were performed and the samples were examined metallographically. Diffusional calculations proved the governing role of carbon activity which is influenced by the distribution of alloying elements.

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Ayçiçek, İlker, e Nuri Solak. "Optimization of Macro Segregation and Equiaxed Zone in High-Carbon Steel Use in Prestressed Concrete Wire and Cord Wire Application". Metals 13, n.º 8 (10 de agosto de 2023): 1435. http://dx.doi.org/10.3390/met13081435.

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In this study, the relationship between macro segregation and the equiaxed zone in high-carbon grades with continuous casting parameters was investigated and optimized at the İsdemir iron and steel plant. The work was conducted for the 1080 quality of the SAE J403 standard. In this study, some parameters, such as casting speed, secondary cooling, EMS current value and EMS frequency value, were examined. When the results of the experiments are examined, it can be observed that the equiaxed zone in the macrostructure decreases significantly with the reduction of the EMS frequency value. The decrease in casting speed and increase in EMS current value caused an increase in the equiaxed zone. The increment in secondary cooling led to a decline in the equiaxed zone. Once the macro segregation results are examined, it can be seen that it is very important to optimize the continuous casting parameters in order to reduce the macro segregation results of—especially—carbon, sulfur and phosphorus elements. It has also been determined that the macro segregation values of carbon, sulfur and phosphorus elements are low in casting conditions where casting speed is low, and the EMS current value and EMS frequency value are high. In addition, macro segregation measurements of manganese, silicon, chromium and vanadium elements are found to be low under similar casting conditions. It is critical to optimize the continuous casting parameters before production, especially in high-carbon grades to be used for prestressed concrete wire and cord wire applications. As a result of the work conducted using the İsdemir billet continuous casting machine for the 1080-grade SAE J403 standard, aiming to optimize macro segregation and the equiaxed zone, the effective results have been achieved by using process parameters of 2.8 m/min casting speed, 360 A EMS current, 5 Hz EMS frequency and low secondary cooling intensity.

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Sun, Hai Bo, Zheng Li, Lie Jun Li e Bao Hua Nie. "A Mathematical Model on Macro-Segregation Formation for Popular Bloom Continuous Casting Process". Materials Science Forum 944 (janeiro de 2019): 770–77. http://dx.doi.org/10.4028/www.scientific.net/msf.944.770.

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A segmented 3-D coupled electromagnetic-thermal solute transportation model, aimed to better understand the macro-segregation formation in the strand during a popular continuous casting (CC) process, has been developed. Based on the model validation by industrial tests, the effect of M-EMS and F-EMS running parameters on the segregation distribution were subsequently carried out. It is shown that the simulated solute segregation profile in the W-shape along the casting thickness direction is in a good agreement with the measured profile. In the initial solidification shell with thickness in 0.020 m, the solute segregation degree changes from a positive value to a negative with the increasing distance from strand surface because of the washing effect induced by the impact flow from the nozzle side port and M-EMS. Here, the minimum degree of carbon segregation decreases from 0.976 to 0.875 with the increasing stirring current from 100A to 550A. As the stirring current of F-EMS decreases from 630A to 200A, the minimum segregation degree locating at 0.109 m distance from strand surface increases from 0.805 to 0.967. The carbon segregation degree at the strand center first decreases from 1.10 to the minimum value of 1.06 at the case of 350 A/4 Hz because of the concentration equilibrium for the local decreasing negative segregation induced by F-EMS, and then increases to 1.16 due to the local poor stirring.

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Steinbeck, J., G. Braunstein, G. Dresselhaus, M. S. Dresselhaus, T. Venkatesan e D. C. Jacobson. "Segregation of impurities in pulsed‐laser‐melted carbon". Journal of Applied Physics 64, n.º 4 (15 de agosto de 1988): 1802–9. http://dx.doi.org/10.1063/1.341779.

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Bets, Ksenia V., Evgeni S. Penev e Boris I. Yakobson. "Janus Segregation at the Carbon Nanotube–Catalyst Interface". ACS Nano 13, n.º 8 (19 de julho de 2019): 8836–41. http://dx.doi.org/10.1021/acsnano.9b02061.

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36

Zhang, Zaoli, Qingying Lin e Zongsen Yu. "Grain boundary segregation in ultra-low carbon steel". Materials Science and Engineering: A 291, n.º 1-2 (outubro de 2000): 22–26. http://dx.doi.org/10.1016/s0921-5093(00)00977-1.

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Brenner, S. S., e Hua Ming-Jian. "Grain boundary segregation of carbon and boron in". Scripta Metallurgica et Materialia 24, n.º 4 (abril de 1990): 667–70. http://dx.doi.org/10.1016/0956-716x(90)90220-b.

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BERGSTRØM, T., S. COWLEY, A. C. FOWLER e P. E. SEWARD. "Segregation of Carbon Paste in a Smelting Electrode". IMA Journal of Applied Mathematics 43, n.º 1 (1989): 83–99. http://dx.doi.org/10.1093/imamat/43.1.83.

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Alaoua, D., S. Lartigue, A. Larere e L. Priester. "Precipitation and surface segregation in low carbon steels". Materials Science and Engineering: A 189, n.º 1-2 (dezembro de 1994): 155–63. http://dx.doi.org/10.1016/0921-5093(94)90411-1.

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Massardier-Jourdan, Véronique, David Colas e Jacques Merlin. "Role of Manganese and Chromium on the Segregation Kinetics of Carbon and Nitrogen to the Dislocations in Ferritic Steels". Materials Science Forum 539-543 (março de 2007): 4303–8. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.4303.

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The thermoelectric power (or TEP) technique was used to determine the segregation kinetics of the interstitial atoms (C or N) to the dislocations in various extra-mild steels submitted to a heavy deformation by cold-rolling when substitutional atoms (Mn or Cr) are simultaneously in solid solution. It was shown that the substitutional atoms (Mn or Cr) have almost no influence on the segregation kinetics of carbon and on the activation energy associated with the segregation of this element. In contrast, these elements tend to delay the segregation kinetics of nitrogen to the dislocations all the more so as their content in solution is high. In the mean time, the activation energy associated with the segregation of nitrogen is increased.

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Kovalev, A., e D. Wainstein. "Modelling of grain boundary segregation kinetics that are responsible on irreversible and reversible temper embrittlement of engineering steels". Journal de Physique IV 120 (dezembro de 2004): 69–77. http://dx.doi.org/10.1051/jp4:2004120007.

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There are presented the computer models of multicomponent grain boundary segregation (GBS) that are formed at quenching or tempering of engineering steels. The modelling of these processes requires different algorithms. The dynamic model of segregation at quenching is based on solution of independent diffusion and adsorption-desorption equations for various impurities in steel tied by feedback. The model of segregation under tempering considers the influence of alloying and tempering parameters on concentration and thermodynamic activity of carbon in the α-solid solution. It is based on regression analysis of experimental data on grain boundaries chemical composition obtained by Auger spectroscopy. There is established that grain boundary enrichment by harmful impurities (S and P) is possible after carbon and nitrogen segregation dissolution. The models allow to analyze the competition of elements during formation of GBS and to establish main factors responsible on development of different kinds of embrittlement in engineering steels with various alloying and content of harmful impurities.

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Sundaralingam, Sathiyapoobalan, e Neela Ramanathan. "A Deep Learning-Based approach to Segregate Solid Waste Generated in Residential Areas". Engineering, Technology & Applied Science Research 13, n.º 2 (2 de abril de 2023): 10439–46. http://dx.doi.org/10.48084/etasr.5716.

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Residential waste is a substantial contributor to solid waste generation, which is approximately around 36.5 million tons annually in India. The waste created in households is not separated at the source. All waste is accumulated in a single waste bin and stashed in a nearby public waste bin, resulting in a massive amount of waste being dumped in landfills and also infused with other types of waste, causing environmental pollution. The core objective of this research is to develop a household waste segregator using the TensorFlow object detection model and Arduino microcontroller. The SSD MobileNet V2 model has been trained with a household dataset consisting of paper, plastic, metal, organic waste, glass, and one more additional empty class to detect whether waste is placed for detection or not. This proposed system can predict the waste class and segregate it into their specific dustbin with mean Average Precision (mAP) and recall of 86.5% and 88.3%, respectively. Waste segregation and recycling can reduce landfills, lower carbon footprints, increase recycling, recover value from garbage, and lower greenhouse gases emitted from waste. Segregation at the source will reduce the cost of the segregation process carried by the municipal solid waste management.

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Song, Xianglian, Lixin Song, Xiaoying Chen e Tao Zhang. "The characterization of graphene prepared using a nickel film catalyst pre-deposited to fused silica". RSC Advances 6, n.º 27 (2016): 22244–49. http://dx.doi.org/10.1039/c5ra26875c.

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Paul, Alan J., e Peter M. A. Sherwood. "An X-Ray Photoelectron Spectroscopic Study of the Free Surface Segregation of Impurities in Platinum and Palladium". Applied Spectroscopy 41, n.º 3 (março de 1987): 516–22. http://dx.doi.org/10.1366/0003702874448896.

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X-ray photoelectron spectroscopy has been used to observe the free surface segregation of impurities in samples of platinum and palladium. Heating in vacuo to 600°C promoted the surface segregation of silver, gold, and carbon in platinum and the surface segregation of silver and sulfur in palladium. All species segregated in their elemental form. The core level binding energies of the silver and gold segregants were lower than those measured for the corresponding pure metal states.

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Hutny, A. M., M. Warzecha, W. Derda e P. Wieczorek. "Segregation of Elements in Continuous Cast Carbon Steel Billets Designated for Long Products". Archives of Metallurgy and Materials 61, n.º 4 (1 de dezembro de 2016): 2037–42. http://dx.doi.org/10.1515/amm-2016-0328.

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Abstract This article presents research results concerning designation of the scope of segregation of elements by analysing the ingot, designated for hot rolling of long products. The research tests were performed under industrial conditions, during continuous casting production cycle of high carbon steels. From cc ingots with square cross-section of 160 mm samples having the length of 400 mm were collected, out of which two samples were cut up, the so-called templates with the thickness of 20 mm. Segregation of elements was determined based on the quantitative analysis of results performed by using spark spectrometry pursuant to PN-H-04045. Changes in concentrations of elements were analysed along the line, which join the opposite sides of the sample in their half length and pass through the geometric centre of the square cross-section. In the further course of the research study, there was also determined the segregation along perpendicular line up to the surface connecting the core of the cross-section with lateral plane. Designations of element contents were performed at points distanced from each other by approx. 10 mm and situated on the lines. There was found segregation of carbon, sulphur and phosphorus.

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Sumi, Y., S. Narita e M. Yamashita. "The macrosegregation behaviour of Fe-C-Cr-Mo type steel in laboratory scale model ingot." IOP Conference Series: Materials Science and Engineering 1274, n.º 1 (1 de janeiro de 2023): 012048. http://dx.doi.org/10.1088/1757-899x/1274/1/012048.

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Abstract In ingot casting, it is important to predict and control segregation and casting defects that occur during the solidification process, because they have a significant effect on the quality of the steel ingot. In some special steels, in typical Fe-C-Cr-Mo type high carbon tool steels, macro-segregation tends to be more pronounced due to their wide solid-liquid coexistence temperature range and molten steel properties such as relatively higher liquid viscosity than basic carbon steels. In order to investigate segregation and defect formation phenomena during solidification, many experiments have been conducted using specially designed laboratory scale model ingots that can induce partial difference of solidification to cause macrosegregation phenomena. However, these kind of experimental approaches for special steels are less conducted and influence of alloy types on the macrosegregation behaviour is still not well understood. In this study, a model ingot which have a steel chill ring in the middle region of a mullite mold was prepared, then Fe-0.45C(mass%) carbon steel, Fe-1C-1.8Cr(mass%) bearing steel and Fe-1C-8Cr-2Mo(mass%) high carbon tool steel were cast into 30kg ingots and the macrosegregation behaviour was investigated.

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Li, Yutang, Haoran Zhu, Dengping Ji, Bin Luo e Jianxun Fu. "Investigation on carbide dispersion modified by magnesium and rare earth in high-carbon martensitic stainless steel". Metallurgical Research & Technology 120, n.º 5 (2023): 510. http://dx.doi.org/10.1051/metal/2023068.

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Fine and uniform carbides play a beneficial role in the high hardness and wear resistance of martensitic stainless steel. This paper investigates the effect of magnesium and rare earth(RE) on the dispersion of carbides in a high-carbon martensitic stainless steel. The results show that RE-Al-O and RE-Al-O-S inclusions were generated in RE-containing steel, while Mg-Al-O+(Ca, Mn)S and MgO+CaS inclusions were in Mg-containing steel. MC, M7C3, and M23C6 types of carbides were detected in both RE-containing and Mg-containing steels, which is consistent with thermodynamic calculation. The RE-Al-O inclusion can act as heterogeneous nuclei for carbides, while Mg-containing inclusions do not promote carbide precipitation for sulfur enrichment. The three-dimensional etching test suggests that RE-containing steel has more serious network carbides and larger carbide sizes than Mg-containing steel. The carbon segregation ratio presents an “M” shape due to δ→γ phase transformation. Rare earth is easy to combine with S and weaken the inhibiting effect of carbon segregation. Thus, magnesium has a stronger inhibitory effect on carbon segregation than rare earth.

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Liu, Xingyu, Guotao Zhou, Yangyang Shen, Wei Yan e Jing Li. "Numerical Investigation on the Electroslag Remelting of High Carbon Martensitic Stainless Steels". Metals 13, n.º 3 (26 de fevereiro de 2023): 482. http://dx.doi.org/10.3390/met13030482.

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Control of solidification structure and segregation is crucial to improve the service performance of high carbon martensitic stainless steels. Design of the electroslag remelting (ESR) process based on the essential parameters of melting rate, filling ratio, and slag thickness is a precondition to achieve optimal control of solidification structure and segregation of the steels. However, there is still a lack of coupled works giving deep insight into the overall effect of the parameters on the expected control. With this background, a 2D numerical model was established to probe into the effect of process parameters. The results showed that: (1) With the increase of melting rate from 90 kg/h to 180 kg/h, the molten metal pool depth increased by about 4 cm. Meanwhile, the center LST, PDAS, and SDAS increased by about 450 s, 100 μm, and 12 μm. The segregation index of C and Cr increased by about 0.15 and 0.09. (2) As the filling ratio increased from 0.16 to 0.43, the depth of the metal pool decreased by about 4.5 cm, LST and SDAS received a slight increase of about 41 s and less than 5 μm, but PDAS had little change. The segregation index of C had an increase of about 0.03, but the segregation index of Cr demonstrated tiny changes. (3) As the slag thickness increased from 0.08 to 0.14 m, the metal pool depth presented a first increase of about 1 cm and then a slight decrease. The center LST, PDAS, and SDAS first increased by 148 s, 30 μm, and 4 μm and then decreased slightly. The changes of the segregation index of C and Cr presented a similar tendency than that of LST, but the changes are extremely small. (4) A low melting rate less than 120 kg/h, a filling ratio of about 0.23–0.33, and a slag thickness of 0.08–0.10 m were appropriate to obtain good performance for ESR of high carbon stainless steels in this study.

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Feng, Zhenhua, Guifang Zhang, Pengchao Li e Peng Yan. "Numerical Simulation of Fluid Flow, Solidification, and Solute Distribution in Billets under Combined Mold and Final Electromagnetic Stirring". Materials 17, n.º 2 (22 de janeiro de 2024): 530. http://dx.doi.org/10.3390/ma17020530.

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In this study, a three-dimensional segmented coupled model for continuous casting billets under combined mold and final electromagnetic stirring (M-EMS, F-EMS) was developed. The model was verified by comparing carbon segregation in billets with and without EMS through plant experiments. The findings revealed that both M-EMS and F-EMS induce tangential flow in molten steel, impacting solidification and solute distribution processes within the billet. For M-EMS, with operating parameters of 250A-2Hz, the maximum tangential velocity (velocity projected onto the cross-section) was observed at the liquid phase’s edge. For F-EMS, with operating parameters of 250A-6Hz, the maximum tangential velocity occurred at fl=0.7. Furthermore, F-EMS accelerated heat transfer in the liquid phase, reducing the central liquid fraction from 0.93 to 0.85. M-EMS intensified the washing effect of molten steel on the solidification front, resulting in the formation of negative segregation within the mold. F-EMS significantly improved the centerline segregation issue, reducing carbon segregation from 1.15 to 1.02. Experimental and simulation results, with and without EMS, were in good agreement, indicating that M+F-EMS leads to a more uniform solute distribution within the billet, with a pronounced improvement in centerline segregation.

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Yogo, Yasu, K. Tanaka, Hideaki Ikehata, Noritoshi Iwata, Kou Nakanishi e T. Ishikawa. "The Solute Drag Model to Calculate Grain Growth Rate at High Temperatures in Carbon Steels". Materials Science Forum 706-709 (janeiro de 2012): 1574–79. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.1574.

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Based on the solute drag model, a practical model incorporating the segregation effect is proposed to calculate grain growth rates in carbon steels. The segregation effect is modeled using two factors: the difference in atomic diameter between a solvent and a substitutional element, and the solubility of a substitutional element. By including the segregation energy, the proposed model enables the simulated retardation of grain growth by the addition of microalloying elements. The calculated grain growth rate by the proposed model shows reasonable correspondence between grain growth rates for experimental and calculated results. The temperature dependence of the grain growth rate is also well simulated.

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