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1
Viñas Farre, Ramón. "L’introduction du droit uniforme de geneve sur la leitre de change, le billet a ordre et le cheque dans le droit espagnol". Uniform Law Review os-15, n. 1 (gennaio 1987): 54–70. http://dx.doi.org/10.1093/ulr/os-15.1.54.
Testo completo
2
Cançado, K. N., L. Machado e L. N. Soares. "ANALYSIS OF HEAT TRANSFER IN STEEL BILLETS DURING TRANSPORT". Revista de Engenharia Térmica 17, n. 1 (30 giugno 2018): 69. http://dx.doi.org/10.5380/reterm.v17i1.62261.
Testo completoAbstract (sommario):
During the seamless steel tubes manufacturing process, the temperature decrease between the exit of the furnace and the rolling mill entrance is determinant factor in the rolling process and the quality of the tube. This study aims to model the cooling of the billets during transport in order to evaluate the minimum temperature required for the billet leaves the furnace and also the maximum transport time without compromising the rolling process, allowing a better setup of equipment and reducing the production costs. The cooling profile was determined numerically through energy balances performed on the billet and the results obtained were compared with real values of temperature measurements by thermocouples installed on the billet. Measurements with thermocouples were conducted in billets of 270, 230 and 180 mm diameter. The error relative to the real values for all cases was below than 2.5% and the model is considered validated to use.
3
Ost, François. "Le Marchand de Venise : le pari et la dette, le jeu et la loi". McGill Law Journal 62, n. 4 (2 febbraio 2018): 1103–52. http://dx.doi.org/10.7202/1043162ar.
Testo completoAbstract (sommario):
Le Marchand de Venise est tenu, à raison, pour une des pièces les plus juridiques de W. Shakespeare, avec Mesure pour mesure. Au coeur du débat, la fameuse clause pénale que l’armateur vénitien Antonio se laisse imposer par le prêteur juif de la place, Shylock : une livre de chair prélevée sur son propre corps, en cas de défaut de paiement. On en retient généralement la tirade de Portia plaidant en faveur de la miséricorde (mercy) du prêteur. Et on lit la pièce comme l’illustration du procès éternel entre la lettre et l’esprit, le formalisme juridique et l’équité. La présente contribution entend discuter cette interprétation traditionnelle en replaçant l’intrigue dans son contexte socio-historique : le casino vénitien, ses jeux de séduction et de pouvoir, et le nécessaire financement des aventures d’Antonio par le ghetto. Mais au-delà de l’analyse juridique et du décryptage sociologique, c’est d’une lecture anthropologique que relève l’écriture de Shakespeare. On comprend alors la pièce comme un affrontement de passions juridiques radicalisées. Pour Shylock, le billet à ordre, assorti de la fameuse clause, est l’occasion d’assouvir enfin une vengeance nourrie d’un ressentiment séculaire. Pour Antonio, joueur invétéré, toute l’affaire est l’occasion de jouer son ultime « va-tout » et de jouir à l’avance d’une partie de « qui perd gagne » — car un armateur vénitien ne peut pas perdre, n’est-ce pas, face à un prêteur juif.
4
Chen, Lin, Guo Chang, Shu Qin Liu e Ke Xin Bi. "The Stress Laws of H-Beam Rolling Deformation during Rectangular Billet Cogging-Down". Advanced Materials Research 631-632 (gennaio 2013): 632–36. http://dx.doi.org/10.4028/www.scientific.net/amr.631-632.632.
Testo completoAbstract (sommario):
In order to ensure H-beam’s organization and performance requirements, there is a certain compression ratio from the rolling of the billet to the finished product. This paper select rectangular billets and use DEFORM finite element software to simulate and analyze the rules of stress variation when rectangular billet is cogged down. The simulation results show that: from rectangular billet to finished product, the compression ratio is 17.4 and after cogging, billet size meet the requirements of the CCS rolling. The equivalent stress of breakdown rolling is mainly concentrated in the waist or in the junction of waist and legs. In the first few pass，equivalent stress is mainly concentrated in Sharp-angled position of both top and bottom, however the next few pass’s equivalent stress is mainly concentrated in the junction of web Plate and flange.
5
Kalitaev, A. N., V. D. Tutarova e A. N. Shapovalov. "Effect of Continuous Casting Parameters on Quality of Billets Manufactured by UMMC Steel LLC". Solid State Phenomena 265 (settembre 2017): 952–61. http://dx.doi.org/10.4028/www.scientific.net/ssp.265.952.
Testo completoAbstract (sommario):
The analysis of the production records on casting 150õ150mm billets at UMMC Steel LLC has made it possible to define the basic factors worsening the billet quality and increasing the rejection of the rolled materials: steel casting in case the sulfur and phosphorus content exceeds 0.015 % and overheat is more than 30°Ñ. In order to minimize the formation of local nonuniformity in the billets manufactured from low carbon and medium carbon steel, open cast by CCM, it is necessary to maintain a maximum [Mn]:[S] ratio with [Mn]:[Si] ratio at the level less than 2-3, which ensures the formation of fusible deoxidation products and prevents the formation of solid conglomerates in steel. In order to reduce the formation of axial porosity it is advisable to retain the carbon content at the lower limit for the steel grade and avoid overheating of steel above the specified values. In order to minimize the consequences of the overheated steel casting it is necessary to adjust the billet casting rate in accordance with the operating procedures.
6
Lee, Dock Young, Ki Bae Kim, Ho In Lee e Do Hyang Kim. "Microstructural Effects of Electromagnetic Stirring Strength and Casting Speed in Continuous Casting of Al Alloy". Materials Science Forum 449-452 (marzo 2004): 321–24. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.321.
Testo completoAbstract (sommario):
Semi-solid forming usually requires feed stock material in form of cylindrical billets with a uniform, globular and fine grain microstructure. These billets are commonly being produced by continuous casting involving agitation of the solidifying melt. The paper will present the development of a horizontal continuous casting machine using circumferential electromagnetic stirring to generate melt flow and shear rate in the continuous casting mould. The machine has been used to study the influence of various process parameters such as electromagnetic stirring strength and casting speed in the production of Al billet with a diameter of 76mm. In order to establish the quantitative relationship between microstructure and the process parameters, the morphology and primary crystal size of billet were observed according to the casting speed and electromagnetic stirring strength. A depth and distance of surface defect on the billet was decreased with increasing a casting speed and a very good smooth surface without any surface defect appeared on the billet produced at a casting speed of 600mm/min. A thickness of the solidifying shell was decreased with increasing the casting speed and the maximum casting speed without a break-out was 600mm/min in horizontal continuous caster designed in this study. Both the size and the aspect ratio of primary crystal were decreased with increasing the casting speed and electromagnetic stirring strength in the range of this study.
7
Krayushkin, N. A., I. A. Pribytkov e K. S. Shatokhin. "FORMATION OF TEMPERATURE FIELDS AND THERMAL STRESSES ARISING DURING SOLIDIFICATION OF CYLINDRICAL CONTINUOUSLY CAST STEEL BILLETS". Izvestiya. Ferrous Metallurgy 62, n. 1 (22 febbraio 2019): 57–61. http://dx.doi.org/10.17073/0368-0797-2019-1-57-61.
Testo completoAbstract (sommario):
The article presents investigation results of the effect of inhomogeneity of boundary conditions on the intensity of metal cooling in the process of continuous casting of cylindrical billets from corrosionresistant steels. It is assumed that the boundary conditions are nonuniform along the billet perimeter. In the longitudinal direction, the cooling intensity is assumed to be constant within the cooled sector of the billet. During the research it was believed that there are flows of thermal energy between the cooling sectors. A comparative analysis of temperature gradients and resulting thermal stresses in the solidified billet at different cooling intensities realized in the secondary cooling zone was carried out The values of thermal stresses are compared with the maximum permissible for each grade of steel in order to find those cooling conditions in which the thermal stresses do not exceed the permissible values. Based on the results obtained, conclusions are drawn about the effect of cooling intensity on the occurrence of external and internal defects in the resulting cylindrical continuous cast billets. The authors have also made the conclusions about the effect of inhomogeneity of the boundary conditions on the formation of temperature fields in a solidified cylindrical continuously cast billet. The results of the conducted studies are presented in a graphic form and their detailed analysis is carried out. To calculate the temperature fields in the solidifying billet, a specially developed mathematical model was used, based on the equation of nonstationary heat conductivity. For the calculation of thermal stresses, known mathematical formulas have been used that allow calculating the values of thermal stresses arising between cooling zones in the solidifying billet during the continuous casting of steel. The obtained data are of high practical importance, since they can be used to develop rational cooling regimes, in which excess permissible thermal stresses will not be observed. This, as a consequence, will reduce the number of internal and external defects arising in the solidifying continuously cast billet.
8
Kim, Jong Ho, Myoung Gyun Kim, Joon Pyo Park, Gyu Chang Lee e Ju Bum Kim. "Electromagnetic Continuous Casting Process for Near Net Shape Aluminum Alloy Billet". Materials Science Forum 654-656 (giugno 2010): 1400–1403. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1400.
Testo completoAbstract (sommario):
A new method and apparatus for the fabrication of high-quality, near net shaped aluminum alloy billets is developed by the combination of continuous casting and electromagnetic casting/stirring technique. Traditional machine for continuous casting process involves round, square and rectangular billets; therefore it requires additional multistep forging process to fabricate final products of complicated shape. A new process for the fabrication of near net shaped aluminum billets offers some advantages: the process of extrusion and forging is simplified and the cost of plastic working can be greatly reduced. In order to reduce the peculiar problems such as surface crack and internal defect due to inhomogeneous heat transfer of solidified billets, electromagnetic casting and stirring technique were adopted. The effect of electromagnetic field was compared by observing the microstructure of billets. Grain refinement of aluminum billet was clearly observed by applying electromagnetic field to continuous casting process.
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Kido, Futoshi, e Tetsuichi Motegi. "Production of Magnesium Alloy Billets by Semisolid Continuous Casting". Materials Science Forum 610-613 (gennaio 2009): 1403–6. http://dx.doi.org/10.4028/www.scientific.net/msf.610-613.1403.
Testo completoAbstract (sommario):
In order to produce AZ91 and AZ31 magnesium alloy billets semisolid continuous casting by using an inclined cooling plate was carried out. The molten magnesium alloy in an electric furnace was flowed on the inclined cooling plate and then poured in a tundish. The slurry prepared using this process was solidified by drawing a dummy bar from a water-cooled copper mold, consequently producing a billet. As a result, we could produce the magnesium alloy billets by semisolid continuous casting. Magnesium alloy billets with refined and globular primary α crystals were successfully and continuously cast by optimizing the solidification conditions. In this case, the grain size of AZ91 billets was about 55μm and that of AZ31 billets was 50μm. The AZ91 billets produced by semisolid continuous casting were employed in thixocasting experiments. The experiments revealed that thixocasting could produce the mobile phone casings with spherical primary α crystals at 858K. Moreover, we proved that the difference of shot cycle did not influence the microstructures for up to 251 shots.
10
Ahmad, Asnul Hadi, S. Naher e Dermot Brabazon. "Injection Tests and Effect on Microstructure and Properties of Aluminium 7075 Direct Thermal Method Feedstock Billets". Key Engineering Materials 611-612 (maggio 2014): 1637–44. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.1637.
Testo completoAbstract (sommario):
The success of semi-solid metal forming is dependent on a globular solid grain formation within a liquid phase. This paper presents experimental works concerning semi-solid metal processing of aluminium 7075 feedstock billets which were produced by direct thermal method. The flowability of feedstock billets was evaluated by an injection test processing unit. The feedstock billets were heated to a temperature of 620 °C by using a box furnace before transferred into a forming die. The formed feedstock billet was removed from the forming die after it was cooled to ambient temperature. Several analyses were conducted on the formed feedstock billets including dimensional measurement and microstructure analysis. The results show that the feedstock billets which contained highest amount of free secondary phase were most successfully formed. Microstructure analysis results also revealed the formation of more globular and larger α–Al solid grains in the same feedstock billets. In this experimental work, the feedstock billets with higher secondary (liquid) phase gives a significant effect to formability. It can be concluded that in order to get successful formability of direct thermal method feedstock billets, the billets need to have higher secondary phase content. Thus, the selection of proper feedstock billets is important to determine the success of the SSM processing.
11
REN, TAO LIN, DE BIN SHAN e YAN LU. "SURFACE PLASTIC DEFORMATION REGULARITY AND MICROSTRUCTURAL EVOLUTION IN THE COMPOUND ROLLING OF Q235 BILLET". International Journal of Modern Physics B 23, n. 06n07 (20 marzo 2009): 1847–52. http://dx.doi.org/10.1142/s021797920906172x.
Testo completoAbstract (sommario):
In order to meet the double demands on the high temperature creep and the fatigue property, compound rolling is put forward in this study. This technique obtains dual microstructures of billet, fine microstructure on the surface and original state microstructure in the center, through localizing the plastic deformation on the surface layer and leaving little plastic deformation in the center. Based on the local load theory, a set of equipment for the compound rolling has been produced. In order to study the deformation regularity of the compound rolling, Q235 billets have been used and the flow net method for strain measurement has been employed. The deformation regularity difference between the compound rolling and the flat rolling has been investigated. In addition, the microstructural evolution after the compound rolling on the surface and in the center of the Q235 billet has been observed. The results indicate that the compound rolling technique will localize the plastic deformation on the surface of the billet but leave little plastic deformation in the center.
12
Shim, Jae Hyun, J. H. Ok, Hyoung Jin Choi, H. S. Koo e Beong Bok Hwang. "A Process Sequence Design of Multi-Step Cold Extrusion Process for Hollow Parts". Materials Science Forum 475-479 (gennaio 2005): 4195–98. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.4195.
Testo completoAbstract (sommario):
Conventional multi-step extrusion processes with solid billet are examined by the rigid-plastic finite element method in order to provide criteria for new process sequence for hollow parts. Two examples are taken for the analyses such as the current three-stage cold extrusion process for a hollow flange part and five-stage process for manufacturing an axle housing. Based on the results of simulation of the current three-stage and five-stage manufacturing processes, new design strategy for improving the process sequences is developed simply by replacing the initial billet from solid to hollow one. The developed new process sequences are applied for simulation by FEM and they are compared with the existing processes to confirm the usefulness of new process sequences with hollow initial billets. The results of simulation show that the newly proposed process sequences with hollow billet instead of solid one are more economical way to manufacture required parts, respectively.
13
Hou, Jin, Ulf Sta˚hlberg e Bo Bengtsson. "Inward Flow of Surface Materials at Back-Ends of Billets During Al-Extrusion, Part 2: Influence of Process Parameters". Journal of Manufacturing Science and Engineering 121, n. 3 (1 agosto 1999): 328–35. http://dx.doi.org/10.1115/1.2832685.
Testo completoAbstract (sommario):
In order to study the inward flow of surface materials at back-ends of billets during Al-extrusion, a FEM model has been proposed and a computer program, named FEMBA, have been developed for PCs. The model and the program FEMBA have been described in part one. In this work, the program FEMBA has been used as a tool to study the flow of surface materials at the back-end under different conditions. The influence of process parameters on the inward flow has been studied. It is found that thickness of surface layer, temperatures and friction at the pad/billet contact surface have significant influence on the inward flow of surface materials. Ram speed can have some influence. The influence of temperatures of the billet, container and pad has been studied separately.
14
Abbas, Adel Taha, Mohamed Adel Taha, Adham Ezzat Ragab, Ehab Adel El-Danaf e Mohamed Ibrahim Abd El Aal. "Effect of Equal Channel Angular Pressing on the Surface Roughness of Solid State Recycled Aluminum Alloy 6061 Chips". Advances in Materials Science and Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/5131403.
Testo completoAbstract (sommario):
Solid state recycling through hot extrusion is a promising technique to recycle machining chips without remelting. Furthermore, equal channel angular pressing (ECAP) technique coupled with the extruded recycled billet is introduced to enhance the mechanical properties of recycled samples. In this paper, the surface roughness of solid state recycled aluminum alloy 6061 turning chips was investigated. Aluminum chips were cold compacted and hot extruded under an extrusion ratio (ER) of 5.2 at an extrusion temperature (ET) of 425°C. In order to improve the properties of the extruded samples, they were subjected to ECAP up to three passes at room temperature using an ECAP die with a channel die angle(Φ)of 90°. Surface roughness (RaandRz) of the processed recycled billets machined by turning was investigated. Box-Behnken experimental design was used to investigate the effect of three machining parameters (cutting speed, feed rate, and depth of cut) on the surface roughness of the machined specimens for four materials conditions, namely, extruded billet and postextrusion ECAP processed billets to one, two, and three passes. Quadratic models were developed to relate the machining parameters to surface roughness, and a multiobjective optimization scheme was conducted to maximize material removal rate while maintaining the roughness below a preset practical value.
15
Semenov, A. B., Thanh Binh Ngo e B. I. Semenov. "Thixoforming of Hypereutectic AlSi12Cu2NiMg Automotive Pistons". Solid State Phenomena 285 (gennaio 2019): 446–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.285.446.
Testo completoAbstract (sommario):
The microstructure and mechanical properties of thixoformed AlSi12Cu2NiMg (AЛ25) aluminium alloy were investigated. Cooling slope method was employed in order to produce non-dendritic billets. Thixoforming process parameters were determined as follows: die temperature of 250 °C, billet temperature of 555 - 560 °C, punch velocity of 7 mm/s. Mechanical properties of automotive piston with ultimate strength of 309 MPa, yield strength of 274 MPa and elongation of 6.8 % in the T6 condition were obtained successfully, implying success of advantages of cooling slope method.
16
Konstantinov, I. L., P. G. Potapov, S. B. Sidelnikov, D. S. Voroshilov, Yu V. Gorokhov e V. P. Katryuk. "Computer simulation of the technology for AK4-1 alloy die forging production for an internal combustion engine piston". Izvestiya Vuzov. Tsvetnaya Metallurgiya (Universities' Proceedings Non-Ferrous Metallurgy), n. 6 (16 dicembre 2020): 24–31. http://dx.doi.org/10.17073/0021-3438-2020-6-24-31.
Testo completoAbstract (sommario):
The process of hot die forging of AK4-1 aluminum alloy billets for the piston of an internal combustion engine (ICE) for an unmanned aerial vehicle (UAV) was simulated using the Deform-3D software package. The object of research was an ICE piston mounted on one of the UAV types of Russian production. Simulation was performed using the following parameters: tooling and billet temperature was 450 °C, ambient temperature was 20 °C, punch speed was 5 mm/s, and Siebel friction index was 0.4. Rigid plastic medium was chosen as a material model. The number of elements (6000) was selected so that at least 3 elements fit in the narrowest section of the part. Thus, as illustrated by the piston die forging, computer simulation in the Deform-3D software makes it possible to develop hot die forging processes for making aluminum alloy billets for UAV ICE pistons. At the same time, computer simulation can be used to evaluate the power parameters of the hot die forging process, study the nature of billet forming in die forging, make necessary adjustments to the virtual process, and develop the design of a die forging tool in order to select the most effective process solutions when designing a real process. The described computer simulation technique can be extended to other aluminum alloy die forgings.
17
Schönbohm, Alexander, Rainer Gasper e Dirk Abel. "Inductive Reheating of Steel Billets into the Semi-Solid State Based on Pyrometer Measurements". Solid State Phenomena 116-117 (ottobre 2006): 734–37. http://dx.doi.org/10.4028/www.scientific.net/ssp.116-117.734.
Testo completoAbstract (sommario):
The aim of the paper is to demonstrate a control scheme by which it is possible to reproducibly reheat steel billets into the semi-solid state. Usually a heating program is used to reheat the billet into the semi-solid state. Our experiments showed that this control scheme leads to varying semi-solid fractions from one experiment to the next. To gain information about the billet’s state its temperature is often used since there is a known relationship between the temperature and the liquid fraction. Direct measurement of the temperature via thermocouples is not feasible in a production environment, therefore a radiation pyrometer has been used as a contact-less measurement device. The accuracy of the pyrometer depends heavily on the exact knowledge of the radiation coefficient, which can vary from billet to billet due to different surface properties and which is subject to change during the heating process. These uncertainties prohibit the implementation of a closed-loop control scheme since the exact temperature cannot be measured with the required accuracy. In order to be independent of the measurement errors the proposed control scheme only relies on the slope of the temperature. By detecting the distinct change of slope which occurs when the solidus temperature is crossed, the beginning of the melting process can be determined. The energy fed to the billet from this point onward determines the resulting liquid fraction. By detecting the entry into the solidusliquidus interval and then feeding the same amount of energy to each billet, it is guaranteed that the billet reaches the desired liquid fraction even by uncertain absolute value of the temperature and by small variations of the alloy composition. For the experiments the steel alloy X210 has been used and measurement data demonstrate the feasibility of the proposed control scheme.
18
Smolyakov, A. S., S. I. Shakhov e B. A. Sivak. "Improvement of the tube mold to ensure uniform primary cooling of the ingot". Ferrous Metallurgy. Bulletin of Scientific , Technical and Economic Information 77, n. 3 (28 marzo 2021): 288–94. http://dx.doi.org/10.32339/0135-5910-2021-3-288-294.
Testo completoAbstract (sommario):
For centering the cooling jackets of CCM tube molds relative to the tube, bolts twisted into the jacket are used. The adjustment is made manually, as a result the annular gap between the sleeve and the jacket can have a significant deviation from the specified values. The gap function is to cool the structure by passing water. Taking into account that almost all the modern CCMs for casting long, bloom and round billets are equipped with tube molds, creating a mold design in which the gap between the tube and the cooling jacket is formed with a high degree of accuracy, ensuring uniform heat removal from the walls of the tube is an urgent task. This is necessary to ensure a uniform thickness of the shell of the solidifying billet. The conditions were considered for the formation of a uniform shell of a solidifying ingot in a mold and the production of a billet that meets the requirements for its surface and geometric dimensions, the absence of internal and external cracks of thermal origin. It was shown that the violation of the alignment of the cooling jacket and the tube surfaces results in violation of the uniformity of the cooling water flow. The difference in the volume of water flowing in various parts of the gap between the tube and the jacket can reach 40%. When casting billets with diameters of 600 and 550 mm, the difference in heat flows due to misalignment in existing molds can be 30–40% and 25–35% respectively, and with a cross section of 300×400 mm – 13–23%. In order to eliminate these shortcomings, a new design of the tube mold was developed in VNIIMETMASH (Moscow), in which the gap between the sleeve and the cooling jacket is formed with high accuracy, ensuring uniform heat removal from the walls of the tube and obtaining a uniform thickness of the shell of the solidifying ingot. This will ensure that the casted billet meets the requirements for its quality parameters and geometric dimensions. The diagram of the designed mold for the bloom CCM, which produces billets with a cross section of 340×380 mm is presented.
19
Kammler, Matthias, T. Hadifi, M. Nowak e A. Bouguecha. "Experimental and Numerical Investigations on Metal Flow during Direct Extrusion of EN AW-6082". Key Engineering Materials 491 (settembre 2011): 137–44. http://dx.doi.org/10.4028/www.scientific.net/kem.491.137.
Testo completoAbstract (sommario):
In extrusion processes metal flow has an important influence on the microstructure and the mechanical properties of the extrudates. Thus, a deep knowledge about the metal flow during the forming process is required as basis for further computations of the microstructure evolution. In this study experimental and numerical investigations on the influence of friction on the metal flow in extrusion processes were carried out using visioplastic methods and finite element method (FEA). The objective was to determine the influence of ram speed, ram displacement and billet temperature on the material flow during extrusion of the aluminum alloy AlMgSi1 (EN AW-6082). For this purpose the forming stroke was varied at constant temperature so that a butt length of 100 mm and 150 mm could be produced. Further the influence of different ram speeds at 4.22 mm/s, 6.33 mm/s and 8.44 mm/s was investigated. In order to identify the metal flow and in special the shear zone as well as the dead metal zone, the billets of 250 mm length and a diameter of 140 mm were prepared with round aluminum indicator pins with a diameter of 4 mm which were placed in the plane of symmetry of the billet. For the experimental investigations a compact direct extrusion press with a nominal force of 10 MN (SMS Eumuco) was used. The numerical simulations were carried out using the commercial FEA system simufact.forming 8.1. After extrusion the billets were cut in the plane containing the indicator pins and the surface was polished and etched. The visioplastically determined flow lines and calculated strains were compared with computed flow lines in order to verify the results and to parameterize the simulation. Tresca’s friction model was used in the simulations to describe the frictional conditions between the billet and the tool components. The results of the experimentally and numerically determined strains of the billet at the container wall show a good similarity. With respect to the rigid modeling of the tool components and the fact that Tresca’s friction model considers relative speeds only indirectly the computed ram force curves show also quite good agreement with measured curves. However, the simulation results demonstrates that in further numerical studies advanced plastic flow criteria and flow rules should be used that take into account the anisotropy and inhomogeneity due to the changing grain size and microstructure of the workpiece material.
20
Thienyaem, Titinai, Khwantri Saengprachatanarug, Saree Wongpichet, Taira Eizo e Prakarn Thongrak. "The Influence of the Metering Device Arrangement to the Discharging Consistency of the Sugarcane Billet Planter". Advanced Materials Research 931-932 (maggio 2014): 1561–67. http://dx.doi.org/10.4028/www.scientific.net/amr.931-932.1561.
Testo completoAbstract (sommario):
Sugar cane is an important economic crop of Thailand, used as a raw material to produce sugar and renewable energy. Due to a labor shortage problem, and an increase in the number of sugarcane combine harvesters, sugarcane billet planters from overseas have become more popular, because they can use seed cane prepared by combine harvesters. In order to maintain a high consistency of billet plating, the harvester discharge mechanism needs to accommodate the physical properties of sugarcane billet of Thai's variety, which vary by breed and harvesting method according to area. Thus, this study aims to find the appropriate arrangement of the metering devices within sugarcane billet planters which are suitable for Thai conditions. The stationary experiments were completed using a testing unit driven by an electric motor. At the initial stage the container of the testing unit was filled with 530 kg of Khon Kaen-3 sugarcane billets. The cleated conveyor belt was placed at the container wall, to act as a metering device for the testing unit. There were 3 arrangements of cleats: (1) a full width cleat, with 150mm cleat space, (2) a full width cleat, with 300mm cleat space, and (3) a half width cleat, with 300mm cleat space each side and 150mm displaced, and all were set and tested at a constant linear conveying speed of 0.2 m/s. The effects of each arrangement for discharge rates and consistency were analyzed. The results showed that the 3rd arrangement gave the best discharge consistency, with a precision index of 51.04%.
21
Donati, Lorenzo, Luca Tomesani, Lorella Ceschini e Iuri Boromei. "Microstructure Prediction in Aluminium Extrusion by Means of FEM Simulation". Advanced Materials Research 23 (ottobre 2007): 157–60. http://dx.doi.org/10.4028/www.scientific.net/amr.23.157.
Testo completoAbstract (sommario):
An original inverse extrusion test was developed in order to study the microstructural evolution in the plastic deformation of 6060 and 6082 aluminium alloys. Sample billets were extracted from commercial logs and subjected to plastic deformation in an inverse extrusion process, particularly aimed at producing different strain and strain rate conditions at representative positions within the billet section. Different experiments were performed at various temperatures and strain rates. The particular thermo-mechanical history of each point in different experiments was then reconstructed by FEM analysis. The cups were sectioned and the microstructure was analysed at some representative locations, to relate it to the FEM simulation results.
22
Meechoowas, Ekarat, Parida Jampeerung, Kanit Tapasa, Usuma Naknikham e Tepiwan Jitwatcharakomol. "Low Melting Glass Billets for Pot Furnace Glass Processing". Key Engineering Materials 608 (aprile 2014): 295–300. http://dx.doi.org/10.4028/www.scientific.net/kem.608.295.
Testo completoAbstract (sommario):
Soda-lime-silica glasses were prepared by the composition range of SiO2 67-72, Na2O+K2O 15-18, CaO+MgO 5-8, BaO 2-4 and ZnO 2 in wt% for producing low melting glass billets. The billet properties were similar to commercial glasses, but higher melting ability. Respecting to thermodynamic calculation approach, the exploited heat (Hex), which was the required heat for melting the batch from atmosphere temperature to the melting temperature, was calculated in order to compare the melting ability. The results represented that glass batches with lower silica content which possessed lower Hex than batch with higher silica and consequently higher melting ability. Therefore, to reduce melting energy, silica content in batches should be as low as possible. Hexof batch with SiO2 67 wt% was 480 kWh/t, while the batch with SiO2 72 wt% was higher, namely 495 kWh/t. In addition, the glass batch with SiO2 67 wt% was completely melted at 1350°C only. Properties of billets were determined, and the coefficient of thermal expansion was 9.6 x 10-6 °C-1. The glass transition point was 535 °C, and the refractive index was approximately 1.52. The study succeeded in producing glass billets with good quality and with melting temperatures lower than 1400°C.
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Chumanov, I. V., M. A. Matveeva e D. V. Sergeev. "INFLUENCE OF CONSUMABLE ELECTRODE ROTATION ON ANISOTROPY OF PROPERTIES OF THE BILLET OBTAINED BY ELECTROSLAG REMELTING". Izvestiya. Ferrous Metallurgy 62, n. 2 (30 marzo 2019): 91–96. http://dx.doi.org/10.17073/0368-0797-2019-2-91-96.
Testo completoAbstract (sommario):
The article presents theoretical substantiation of the influence of electroslag remelting technology with rotation of consumable electrode on physicomechanical properties of the formed casting (billet). The technology of electroslag remelting with rotation of consumable electrode around its own axis leads to formation of upward flow of heat in the slag bath, making hydrodynamic environment in mold more rational from the point of using generated heat. During rotation of consumable electrode, centrifugal forces act on liquid metal film formed at the end of the electrode, providing radial flow of molten metal droplets. Subsequent separation occurs from the outer perimeter of electrode. Thus, drops of electrode metal fall into the metal bath closer to the wall of the mold, aligning temperature front of the bath. Decrease in temperature gradient of bath over the cross section leads to a flatter crystallization front. Studied technology of electroslag remelting with rotation of consumable electrode should have an impact on physical and mechanical properties of resulting casting (billet). In order to establish effect of rotation of consumable electrode during electroslag remelting on properties of metal obtained, experimental remelting was carried out. The article presents data on experimental electroslag remelting of electrodes of 20Kh13 grade steel using various technologies at A-550 unit. In course of experiment, influence of rotation technology of consumable electrode on conditions of remelting process, billet crystallization, changes in mechanical and physical properties was established. The influence of remelting method on complex properties of resulting billet was analyzed. As the main research tool, processing of the obtained data on microhardness, density, dendritic cell size of experimental samples was used. Analysis of the research results of billets in transverse direction showed an increase in microhardness uniformity in implementation of electroslag remelting technology with rotation of consumable electrode along the course of smelting. It is also shown that use of the rotation technology reduces size of dendritic cell of billet and increases density of the ingot formed in comparison with traditional technology without rotating electrode.
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Zhang, Bao Hong, e Zhi Min Zhang. "Effect of Extrusion Ratio on Microstructure and Mechanical Properties of As-Cast AZ91D Magnesium Alloy". Advanced Materials Research 445 (gennaio 2012): 237–40. http://dx.doi.org/10.4028/www.scientific.net/amr.445.237.
Testo completoAbstract (sommario):
In order to study the effect of deformation extent on microstructure and mechanical properties of as-cast AZ91D magnesium alloy, experiments of direct extrusion were performed at temperature of 420 and different extrusion ratios. The microstructure and mechanical properties of billets and extrudates were measured. Experimental results show that the grain size of as-cast AZ91D magnesium alloy can be dramatically refined by extrusion. Direct extrusion can obviously improve the mechanical properties of as-cast AZ91D magnesium Alloy, comparing with the pre-extruded billet, the tensile strength, yield strength and elongation of extrudate can be improved by at least 83%, 154% and 150% respectively. As the extrusion ratio increases, the tensile strength and yield strength of extrudate will increase at first and then fall.
25
Puteev, V. S., S. A. Savchenko, I. A. Pankovets, V. I. Voznaja e I. V. Astapenko. "Improvement of the technological process of manufacturing bearing grades of steel at the 370/150 mill." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), n. 3 (10 settembre 2021): 65–73. http://dx.doi.org/10.21122/1683-6065-2021-3-65-73.
Testo completoAbstract (sommario):
The actual problem of obtaining long products from bearing steel grades with specified microstructure characteristics is considered. The analysis of the capabilities of the existing equipment – a heating furnace and a rolling mill 370/150 of OJSC “BSW – Management Company of the Holding “BMC” was carried out in order to introduce technical measures aimed at reducing carbide heterogeneity in products made of bearing steel grades on the example of steel grade 100Cr6.The influence of different modes of preliminary thermal preparation of continuously cast billets from bearing steel grades on the carbide inhomogeneity in the finished rolling is studied. According to the results of the research, the optimal mode of heat treatment of a continuously cast billet was determined, which allows to produce rolled products that meet the highest requirements of consumers.
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Zhang, Yin Juan. "Research of Billet Heating Optimal Strategy Oriented to Energy Saving". Advanced Materials Research 512-515 (maggio 2012): 1303–6. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.1303.
Testo completoAbstract (sommario):
The character of billet heating is studied, in order to improve the billet heating quality and save energy, the prediction model within a billet temperature field is established. The billet heating process is carried on the modeling successful used finite element analysis. Based on analysis of billet heating model and ANSYS software, the temperature field in billet and the temperature setting of reheating furnace are combined, two methods are put forward of temperature optimal setting, the heat transfer situation and temperature field distribution within billet has been reappeared in the billet heating process, the optimal energy saving strategy of billet heating has got.
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Cerri, Emanuela, P. P. De Marco e Paola Leo. "A Multipass ECAP Study of Modified Aluminium Alloys". Materials Science Forum 604-605 (ottobre 2008): 163–70. http://dx.doi.org/10.4028/www.scientific.net/msf.604-605.163.
Testo completoAbstract (sommario):
ECAP (Equal Channel Angular Pressing) is a very interesting method for modifying microstructure in producing UFG (Ultra Fine Grained) materials. It consists of pressing test samples through a die containing two channels, equal in cross section and intersecting at an angle Φ. As a result of pressing, the sample theoretically deforms by simple shear and retains the same cross sectional area to repeat the pressing for several cycles. 2-D and 3-D FEM simulations of both one and four ECAP passes of two modified aluminium alloys were performed in order to investigate the deformation state of processed workpiece and, moreover, the effect of the different alloy related Strain Hardening Rate (SHR), die geometry (in terms of variation of channel outer angle) and friction on deformation distribution and magnitude. FEM results showed a lower equivalent plastic strain on the outer side of both cross and longitudinal sections of the billets after one and four passes. Microhardness tests performed on the same sections of ECAP processed billets supported these findings. Moreover, FEM analysis indicated that an higher SHR means a greater strain inhomogeneity on cross section of the processed billet. The same effect was observed by increasing the channel outer angle by computing friction.
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Katsivarda, Marianna, Athanasios Vazdirvanidis, George Pantazopoulos, Nikos Kolioubas, Sofia Papadopoulou, Andreas Rikos, Eugenia Spiropoulou e Spyros Papaefthymiou. "Investigation of the Effect of Homogenization Practice of 6063 Alloy Billets on Beta to Alpha Transformation and of the Effect of Cooling Rate on Precipitation Kinetics". Materials Science Forum 941 (dicembre 2018): 884–89. http://dx.doi.org/10.4028/www.scientific.net/msf.941.884.
Testo completoAbstract (sommario):
A joint research project was accomplished with the aim to determine the effect of homogenization conditions (temperature, time, cooling rate) on the microstructure and hardness of 6063 alloy billets. Homogenization is crucial for the ability to extrude the piece in low cost, but mainly without defects. Thus, it is of importance to determine the most suitable homogenization conditions (temperature, time, cooling rate) and its effect on both microstructure and hardness of 6063 alloy billets. Furthermore, the size and morphology of the AlFeMnSi intermetallic particles (mean diameter, aspect ratio) and the precipitation behavior of Mg2Si constituents are examined in detail via optical (OM) and scanning electron microscopy (SEM). The resulting mean diameter and aspect ratio data generated by such measurements using OM and image analysis of the intermetallics, that are relevant to the extent of beta-to-alpha transformation, are statistically processed with “ANOVA”. Differential Scanning Calorimetry (DSC) tests are used to determine the coherency level of the particles that were precipitated during the different cooling rates and to reveal the potential for resolutioning the precipitates during billet preheating. Samples received from the plant are compared to laboratory samples in order to facilitate the process of optimization the thermal treatment and improve extrudability.
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Chaengkham, Pongsak, e Panya Srichandr. "Modular Horizontal Continuous Casting Machine: Meeting the Challenge of Flexible Manufacturing of the Future". Key Engineering Materials 419-420 (ottobre 2009): 349–52. http://dx.doi.org/10.4028/www.scientific.net/kem.419-420.349.
Testo completoAbstract (sommario):
Manufacturing of the future has to be more flexible and versatile in order to meet the ever changing needs of the customer. Most continuous casting machines today are rather inflexible in that they are designed to cast specific types of alloys and with limited size ranges, thus suitable for the mass production paradigm. This paper reports the design and development of a modular horizontal continuous casting machine (HCCM). The aim is to have a machine that can continuously cast a variety of ferrous alloys from carbon steels, low alloy steels, stainless steels to cast irons, and with ranges of cross-sectional areas. The modular design approach and quick changing techniques are employed as the key design concept. The construction of the first prototype of the machine is completed and several field trials have been conducted. The results are promising. For carbon and low alloy steel billets, the overall structures and surface quality are good although the amount of porosities is rather large. The overall quality of stainless steel billets is better than that of carbon and low alloy steels. Adapting and setting up the machine for casting different alloys and/or different billet sizes require a little time, no more than 20 minutes.
30
Korzhyk, V. N., L. D. Kulak, V. E. Shevchenko, V. V. Kvasnitskiy, N. N. Kuzmenko, X. Liu, Yi Xiang Cai, L. Wang, H. W. Xie e L. M. Zou. "New Equipment for Production of Super Hard Spherical Tungsten Carbide and other High-Melting Compounds Using the Method of Plasma Atomization of Rotating Billet". Materials Science Forum 898 (giugno 2017): 1485–97. http://dx.doi.org/10.4028/www.scientific.net/msf.898.1485.
Testo completoAbstract (sommario):
In order to ensure high wear resistance of parts and tools, operating at significant dynamic loads in the extreme conditions, the layers different in their function purpose obtained using surfacing methods are widely used. In such surfacing compositions, the powders of high-melting compounds characterized by high hardness and strength, are used as a wear resistant component, for example, alloys of tungsten carbide WC + W2C (cast tungsten carbide), and as binder matrix the plastic and metal alloys are used.The great interest is the development of methods allowing producing powders of cast tungsten carbide and other high-melting-point materials of uniform composition, characterized by a high sphericity of the particles and having higher physical-mechanical properties. The spherical tungsten carbide was produced by plasma atomization of rotating billet. The universal installation for production of super-hard spherical tungsten carbide and other high-melting-point compounds by plasma atomization of rotating billets was designed for industrial application. The results showed that the application of the technology of plasma rotary atomization of rotation billet to obtain granules of powders of high-melting-point materials was promising, in particular tungsten carbide with sphericity over 90%, microhardness HV0.1 more than 3000 kg / mm2 characterized by high flow ability more than 7.5 s/ 50 g. Due to the use of new materials and innovative design and technological solutions the high reliability, maximum interval of technical service, high resource of operating units and executing mechanism of the equipment were ensured. Due to the use of new high-power plasma system with power supply source with high efficiency coefficient and improved dynamic characteristics, the system of preliminary heating of billets, innovative gas systems, high performance vacuum system, the developed universal system for the production of granules of powders of high-melting-point material were also applicable for the manufacture of spherical powders of metals and alloys, including highly active, and provided lower costs of products (powder) with an increased productivity, economic efficiency of the atomization process and reduced the impact of atomization process on the environment.
31
Hnatushenko, V. V., T. A. Zheldak e L. S. Koriashkina. "Mathematical model of steel consumption minimization considering the two-stage billets cutting". Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, n. 2 (2021): 118–24. http://dx.doi.org/10.33271/nvngu/2021-2/118.
Testo completoAbstract (sommario):
Purpose. To achieve a decrease in energy and resource costs in the multi-stage production of rolled products within a given plan through the development of appropriate mathware. Methodology. The multi-stage problem mathware for producing rolling steel products is developed on the basis of system approach applying fundamental principles of the optimization and operation research theory. Realization of the developed mathematical model allows discovering such a strategy of using steel during the whole manufacturing process, which minimizes not only the steel waste at the moment of its casting in a mold, but also the offcuts in the process of cutting the obtained ingots into the billets. Findings. A mathematical task model is built to minimize the amount of steel for producing a certain order of size of one cast volume only. The developed model specifies the possibility to pre-evaluate the billet optimal size, based on the necessary cutting along the final product length, appropriate for the certain billet form of section, and ingot weight limits. Originality. A mathematical model is provided for the optimal metal distribution process when implementing the plan of manufacturing rolling products. The model, in contrast to the existing ones, shifts the emphasis on forming the optimal ingot weight, which has a pre-calculated optimal cutting plan. Practical value. The use of the developed mathematical optimization model (minimizing the amount of steel for producing a certain order) as part of an automated decision support system for management of rolling production will reduce the number of cutting machine changeover and minimize resources use and stock balance.
32
Wang, Zhen Yu, Ze Sheng Ji, Hong Yu Xu e Tie Lei Zhang. "Coarsening Mechanism of Isothermal Heat Treatment for ADC14 Semi-Solid Alloy". Solid State Phenomena 192-193 (ottobre 2012): 123–29. http://dx.doi.org/10.4028/www.scientific.net/ssp.192-193.123.
Testo completoAbstract (sommario):
The strain-induced melt activation (SIMA) process is one form of the thixoforming for aluminum alloy. However, the non-uniform stress distribution restricts its application. In order to avoid this problem, a chip recycling strain-induced melt activation (CR-SIMA) process has been developed to prepare semi-solid billet. Microstructures of semi-solid ADC14 aluminum alloy billets heated to different temperatures and held for various times were investigated. The typical semi-solid microstructure with globular solid particles distributed in the liquid matrix is obtained in the temperature range of 560 and 565oC. The spheroidizing mechanism of ADC14 alloy prepared by the CR-SIMA process was studied. It was found that the severe deformation not only influences the solidification of spherical α-Al particles, but also affects the morphology of primary Si. The primary Si phases become tiny particles and distribute around the α-Al particles.
33
Srinivasan, R., B. Cherukuri e Prabir K. Chaudhury. "Scaling up of Equal Channel Angular Pressing (ECAP) for the Production of Forging Stock". Materials Science Forum 503-504 (gennaio 2006): 371–78. http://dx.doi.org/10.4028/www.scientific.net/msf.503-504.371.
Testo completoAbstract (sommario):
Over the past two decades equal channel angular processing (ECAP) and other severe plastic deformation (SPD) processes have been shown, in the laboratory scale, to produce material with promising properties for industrial applications. In particular, ultrafine grain (UFG) metals produced by ECAP process, for example, have been shown to exhibit higher strain rate sensitivity at lower temperatures and higher strain rates. These factors translate to improved hot formability. However, scale up of these processes to manufacture industrial size components has not been widely undertaken. In this study, billets of annealed AA6061 with 12.5 mm (0.5-in), 50 mm (2-in) and 100 mm (4-in) square cross section were ECAP processed. For the first time, these larger SPD billets were used as starting stock for subsequent hot forging. Several parts were forged on an industrial scale press with the UFG material, as well as conventional stock materials. These parts varied in complexity, as well as size in order to cover the variability in industrial components. This paper will present the effect of scaling up on the mechanical properties, microstructure, and the hot workability of the alloy from the laboratory scale (12.5 mm) to industrial scale (100 mm). Results show that both the forging temperature of the billets and the starting billet size can be substantially decreased compared to conventional forging practice. Therefore, the use of SPD materials, as forging stock, results in decreased energy usage and increased material yield. Results presented will include examples of forged parts, estimated energy savings associated with the use of SPDUFG stock, and properties after forging and subsequent heat treatment.
34
Harel, Galia, Menachem Bamberger, Y. Rami, S. Spigarelli, Mohamad El Mehtedi e Giuseppe Cupitò. "DC Casting - Simulation and Microstructure of Mg-Zn Alloys". Materials Science Forum 638-642 (gennaio 2010): 1518–23. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.1518.
Testo completoAbstract (sommario):
The market share of wrought Magnesium products such as structural and functional components is recently increasing. Extrusion at elevated temperatures is used to produce reliable plastic deformation, since magnesium alloys have limited ductility at room temperature. In order to produce sound extruded products, high quality billets are required. Understanding the influence of direct chill casting conditions on the production properties such as quality, safety, workability and microstructure have a profound importance. Comprehensive computer simulations were used in order to model the casting so that process parameters can be identified and controlled, resulting in significant benefits. The aim of modeling is to provide temperature profiles for a more accurate solidification analysis, predict the solidification time and the effect of cooling on the solidification. The experimental study included castings of several Magnesium alloys, each with 7 (seven) thermocouples that were submerged into the billet. Verification of the simulations was carried out based on the data collected. Complimentary work was conducted on microstructure analysis in as cast and as-extruded states.
35
Yang, Tung Sheng, J. Y. Li e C. Y. Liu. "Study on the Maximum Forging Load and Final Face Width of Powder Spur Gear Forging". Materials Science Forum 697-698 (settembre 2011): 420–23. http://dx.doi.org/10.4028/www.scientific.net/msf.697-698.420.
Testo completoAbstract (sommario):
Powder forging combines powder metallurgy and forging technology, thus possess the advantages of both processes that result in both stronger and yet more versatile products with complicated geometry and arbitrary alloy compositions. For complete filling up, predicting the power requirement and final face width is an important feature of the powder forging process. In this paper, a finite element method is used to investigate the forging force, the final face width and the density variation of the spur gear powder forging process. In order to verify the FEM simulation results, the experimental data are compared with the results of the current simulation for the forging force and the final face width of spur gear. The influences of the parameters such as modules, number of teeth, the initial relative density, the ratio of the height to diameter of billet and friction factor on the forging force and the final face width of the billets are also examined.
36
Pallikonda, Mahesh K., e Taysir H. Nayfeh. "Experimental Investigation to Study the Feasibility of Fabricating Ultra-Conductive Copper Using a Hybrid Method". Materials 14, n. 19 (25 settembre 2021): 5560. http://dx.doi.org/10.3390/ma14195560.
Testo completoAbstract (sommario):
Ultra-conductive copper (UCC) has an enormous potential to disrupt the existing electrical and electronic systems. Recent studies on carbon nanotubes (CNTs), a new class of materials, showed the ballistic conductance of electricity. Researchers around the world are able to demonstrate ultra-conductivity in micro- and millimeter-length sections using various processing techniques by embedding CNTs in the copper matrix. Although multiple methods promise the possibility of producing copper-based nanocomposites with gains in electrical conductivity, thus far, scaling up these results has been quite a challenge. We investigated a hybrid method of both hot-pressing followed by rolling in order to produce UCC wire. Cu/CNT billets of 1/10%, 1/15%, and 1/20% were hot-pressed and the conductivity results were compared to a hot-pressed pure copper billet. Our results indicated that this method is not a viable approach, as the gains in electrical conductivity are neutralized, followed by attenuation of the wire cross-section.
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Olmedo, Bladimiro Hernán Navas, e Hernán Alberto Navas Moscoso. "Comparación y Efecto del Homogenizado en Billets de Aluminio AA 6063". KnE Engineering 3, n. 1 (11 febbraio 2018): 322. http://dx.doi.org/10.18502/keg.v3i1.1437.
Testo completoAbstract (sommario):
The lack of comparative studies about the distribution of the main alloying elements along aluminum billet´s AA 6063 widely use in extrusion companies to produce aluminum profiles, It makes necessary to counterpoise the difference between homogenized billet produced in horizontal continuous casting machine and a billet produced in vertical semi-continuous casting process. Applying spectrometric tests to quantify the weight percent of main alloying elements, brings out its own nature of each production process on every billet. Nevertheless, helped out by a metallographic test reveals in one billet the negative effect of an inadequate process of homogenization after the heat treatment process T5 in the aluminum profiles that holds it back to reach an adequate Webster hardness related to quality assurance. It reflects that is not enough to have a billet with a uniform chemical composition but the importance of an adequate billet´s heat treatment in order to be use in the extrusion process.Keywords: AA 6063, Billet, Comparison, Homogenized
38
Lorbiecka, Agnieszka Zuzanna, e Božidar Šarler. "A Sensitivity Study of Grain Growth Model For Prediction of ECT and CET Transformations in Continuous Casting of Steel". Materials Science Forum 649 (maggio 2010): 373–78. http://dx.doi.org/10.4028/www.scientific.net/msf.649.373.
Testo completoAbstract (sommario):
A two dimensional model was developed to predict the grain structure (Equiaxed to Columnar Transformation (ECT) and Columnar to Equiaxed Transformation (CET) in the continuous casting of steel. The processes of nucleation, growth and impingement of the grains are modelled as follows: (I) the nucleation is modeled through a continuous dependency of the nucleation density on temperature by the Gaussian distribution. Different nucleation parameters are used at the boundary and in the bulk region. (II) The growth and impingement are modeled by the Kurz, Giovanola, Trivedi (KGT) model. The Cellular Automata (CA) technique is used to solve the model. The CA method is based on the Nastac’s and simplified neighborhoods. Calculations are shown for square billets of the dimension 140 mm. Fixed input parameter of the model represents the macroscopic temperature field obtained from the Štore Steel billet simulation system [1]. All other grain structure physical model parameters are varied, such as: the surface and the bulk area, mean nucleation undercooling, standard deviation of undercooling, maximum density of nuclei. The computational parameters, such as the micro mesh size and the time step are varied as well. The influence of the variation of different parameters on calculated grain structure is shown. Finally, the model parameters are adjusted in order to obtain the experimentally determined actual billet ECT and CET positions for 51CrV4+Mo spring steel (Al: 0.02, Cr: 1.05, Cu: 0.125, Mn: 0.9,Mo: 0.025, Ni: 0.1, Si: 0.275, V: 0.155, C: 0.51, P: 0.0125, S: 0.0275 wt%). A systematic procedure is outlined for adjusting of the model data with the experiment.
39
Luo, Guang Zheng, Xin Liu, Ying Zhi e Xiang Hua Liu. "Simulation to the Temperature Field for Continuous Casting Billet during Direct Rolling of Free-Heating". Advanced Materials Research 941-944 (giugno 2014): 1890–94. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.1890.
Testo completoAbstract (sommario):
The temperature field of continuous casting billet (CC-billet) is important to carry out the research on direct rolling of free-heating (DROF). The solidification and the heat transfer process of CC-billet from crystallizer to cutting point were studied by finite element method (FEM).The casting speed was improved in order to get reasonable temperature field during DROF.
40
Clitan, Iulia, Vlad Mureşan, Andrei Florin Clitan e Mihail Abrudean. "Fractional Order Model Identification for a Billet Unloading Robotic Arm". Applied Mechanics and Materials 841 (giugno 2016): 234–39. http://dx.doi.org/10.4028/www.scientific.net/amm.841.234.
Testo completoAbstract (sommario):
This paper presents a fractional model identification for a billet unloading robotic arm’s positioning system. First, an integer order model is obtained using a graphical identification method based on a set of experimental data. The experimental data represents the robotic arm’s position, measured using an encoder, at a constant billet displacement. The integer order model was obtained based on the overall performances of the measured robotic arm’s step response. The mean square error between the measured data and the model step response is high, thus, in order to decrease the error and to obtain a more accurate model, a fractional order model is determined using an iterative procedure.
41
Zhang, Bao Hong, e Zhi Min Zhang. "Influence of Hot Extrusion on Microstructure and Mechanical Properties of As-Cast AZ91 Magnesium Alloy". Materials Science Forum 704-705 (dicembre 2011): 892–96. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.892.
Testo completoAbstract (sommario):
In order to study the effect of plastic deformation on microstructure and mechanical properties of as-cast AZ91 magnesium alloy, experiments of hot direct extrusion were performed at different extrusion temperatures and different extrusion ratios. The microstructure and mechanical properties of extruded billets and extrudate were measured. Experimental results show that the grain size of as-cast AZ91 magnesium alloy can be dramatically refined by extrusion. Hot extrusion can obviously improve the mechanical properties of as-cast AZ91 magnesium Alloy, comparing with the pre-extruded billet, the tensile strength, yield strength and elongation of extrudate can be improved by at least 69%, 117% and 150% respectively. As the extrusion temperature increases, the tensile strength and yield strength of extrudate will increase. As the extrusion ratio increases, the tensile strength and yield strength of extrudate will increase at first and then fall. At the time of extrusion temperature of 420°C and extrusion ratio of 45, the highest tensile strength of 381Mpa and yield strength of 303MPa can be achieved for the extrudate.
42
Omura, Naoki, Yuichiro Murakami, Ming Jun Li, Takuya Tamura e Kenji Miwa. "Effect of Volume Fraction Solid and Injection Speed on Mechanical Properties in New Type Semi-Solid Injection Process". Solid State Phenomena 141-143 (luglio 2008): 761–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.761.
Testo completoAbstract (sommario):
We have developed new type semi-solid injection process, that is, runner-less injection process which can obtain high material yield of about 90% for magnesium alloy. In this process, alloy billets are heated to the semi-solid temperature in the injection cylinder and are injected into a permanent mold. In order to investigate the effects of volume fraction solid and injection speed on microstructure and mechanical properties of AZ91D magnesium alloy injected into the permanent mold, semi-solid forming testing machine which has the same system as a runner-less injection machine, has been made on an experimental basis. The magnesium billet precisely controlled at given temperature has been injected into a permanent mold with two kinds (slow and high) of speed and plate-like specimens with each fraction solid have been fabricated. Microstructure has been observed by optical microscopy and X-ray computerized tomography (CT) scanner. Mechanical properties have been measured by tensile test. The effects of volume fraction solid of the alloy slurry and injection speed on mechanical properties have been clarified.
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Liu, Yun Zhong, e Yuan Yuan Li. "Numerical Simulation of Thermal History in a Novel Spray Forming Process". Materials Science Forum 539-543 (marzo 2007): 1171–76. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1171.
Testo completoAbstract (sommario):
A novel spray forming process was developed to produce large billets, wide plates or thick tubes with excellent microstructures and high cooling rates. Its uniqueness lies in a combination of the wide-range reciprocating movement and the swing scan of a gas atomizer, and the externally forced cooling of substrate during this spray deposition procedure. Its basic concept is that both good sticking and rapid solidification can be achieved if droplets with high liquid fractions impact a cold substrate, spread fully and then deposit on the surface. In order to control and optimize this new process, the thermal histories of droplets and deposits for spray forming of aluminum alloy billets were simulated with a set of new numerical models. Through shortening spray distance and raising melt superheat properly, the liquid fraction of droplets before deposition will increase and their spread on the deposit surface can improve for good sticking. Simulation results show that the optimal liquid fraction of droplets for deposition is about 0.2 higher than that in the conventional Osprey process. Its optimum spray distance is about 0.25m, which is nearly half as that in the Osprey process. In addition, this new process increases the mushy layer area and the specific surface area of heat extraction during deposition. Together with the forced cooling of substrate, it results in higher cooling rates. A high-quality large billet can be obtained by controlling the atomizer movement, the droplet liquid fraction and the deposit surface temperature properly in this new process.
44
Ji, Li. "The Production and Experience of Hot Charging Process of Concasting Billet". Advanced Materials Research 662 (febbraio 2013): 666–69. http://dx.doi.org/10.4028/www.scientific.net/amr.662.666.
Testo completoAbstract (sommario):
Practice of hot charging process of concasting billet，is a process technology which is encouraged by nation industrial policy. It makes use of the sensible heat of conticasting billet, and can save energy consume, cut production cycle, improve product quality, advance recovery of metal and reduce cost of production. Motor transport, assort thermal retardation in burial pits, transfer component by computer, self-action assort group batching by computer are used by LongSteel, can solve various contradicitions of hot charging process of concasting billet, ensure the order of elevated temperature billet hot charging process, produce considerable economic benefit and offer experience for generalization and application.
45
Yang, Tung Sheng, e Yu Liang Chang. "Application of FEM and Abductive Network to Determine Forging Force and Billet Dimensions of Near Net-Shape Helical Bevel Gear Forging". Materials Science Forum 920 (aprile 2018): 205–10. http://dx.doi.org/10.4028/www.scientific.net/msf.920.205.
Testo completoAbstract (sommario):
In this paper, the use of the finite element method in conjunction with abductive network is presented to predict the maximum forging force and the volume of billet during near net-shape helical bevel gear forging. The maximum forging load and volume of billet are influenced by the process parameters such as modules, number of teeth, and die temperature. A finite element method is used to investigate the forging of helical bevel gear. In order to verify the prediction of FEM simulation for forging load, the experimental data are compared with the results of current simulation. A finite element analysis is also utilized to investigate the process parameters on forging load and volume of billet. Additionally, the abductive network was applied to synthesize the data sets obtained from the numerical simulation. The prediction models are then established for the maximum forging load and volume of billet of near net-shape helical bevel gear forging under a suitable range of process parameters. After the predictions of the maximum forging force and the volume of billet, the optimum of the power of forging machine and the dimensions of billet are determined.
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Zhang, Hai Tao, Hiromi Nagaum, Yu Bo Zuo e Jian Zhong Cui. "Numerical Modeling of Low Frequency Electromagnetic Casting of 7XXX Aluminum Alloys". Materials Science Forum 546-549 (maggio 2007): 707–12. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.707.
Testo completoAbstract (sommario):
Low frequency electromagnetic casting is a new developed technology that appears in the recent years. In this paper, a comprehensive mathematical model has been developed to describe the interaction of the multiple physics fields during LFEC (low frequency electromagnetic casting) process. The model is based on a combination of the commercial finite element package ANSYS and the commercial finite volume package FLUENT, with the former for calculation of the electromagnetic field and the latter for calculation of the magnetic driven fluid flow, heat transfer and solidification. Moreover, the model has been verified against the temperature measurements obtained from one 7XXX aluminum alloy billet of 200mm in diameter, during the LFEC casting processes, respectively. There was a good agreement between the calculated results and the measured results. Further, the effects of electromagnetic frequency on fluid flow, temperature field and solidification during LFEC process have investigated numerically by using the mathematic model. The choosing criterion of the electromagnetic frequency during LFEC process has been used in order to obtain the best structure of the billets by analyzing the effects of fluid flow and temperature field on the solidification process in the presence of electromagnetic field.
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Li, Mu Yi, Yan Hu e Hai Hao. "Continuous Casting of a Multi-Crystalline Silicon Billet". Materials Science Forum 833 (novembre 2015): 112–16. http://dx.doi.org/10.4028/www.scientific.net/msf.833.112.
Testo completoAbstract (sommario):
In order to improve the production efficiency, numerical simulation and experiments of continuous casting of a multi-crystalline silicon (mc-silicon) billet were carried out. Modeling works were done firstly to optimize casting recipe and predict billet cooling behaviors, a three-dimensional finite element model for the simulation of thermal field and fluid flow was built. The continuous casting of cylindrical silicon billet was studied considering different casting parameters such as withdrawal speed and heat transfer ability of mold. The simulation results indicate that lower casting speed and lower heat transfer coefficient of mold are beneficial to acquire better morphology. Experimental works were practiced lying on the modeling results, using the self-designed mc-silicon continuous casting apparatus, mc-silicon billet with a diameter of 100 mm was obtained.
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Hou, Jin. "Inward Flow of Surface Materials at Back-Ends of Billets During Al-Extrusion, Part 1: A Finite Element Model". Journal of Manufacturing Science and Engineering 121, n. 3 (1 agosto 1999): 321–27. http://dx.doi.org/10.1115/1.2832684.
Testo completoAbstract (sommario):
In hot extrusion of Al-profiles, the billet-container boundary is characterized by the sticking condition. The outer surface layer of the billet is stuck to the container wall. At the back-end of the billet, the metal flow is complicated. The surface material, which is initially stuck to the wall, will be scraped away by the pad and flow inward into the billet. This kind of inward flow of surface material is usually undesirable and it is important to control such flow so that no surface material should be found in extruded profiles. In order to study this phenomenon, a model is proposed for the metal flow at the back-end, in which the rigid-plastic FEM is used. A computer program FEMBA has been developed based on the model. The simulation results are in qualitatively good agreement with experiments.
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Gasper, Rainer, Alexander Schönbohm, Manfred Enning e Dirk Abel. "Flatness Based Control of Inductive Heating of X210CrW12 into the Semi Solid State". Solid State Phenomena 141-143 (luglio 2008): 127–32. http://dx.doi.org/10.4028/www.scientific.net/ssp.141-143.127.
Testo completoAbstract (sommario):
The inductive heating of the feedstock material is a very important step in the processing of semi solid metals. On the one hand, the billet has to be heated as fast as possible to the target temperature. On the other hand, it must be guaranteed that the outer area does not begin to melt prematurely. Also, at the end of the heating the billet should have an uniform temperature distribution in order to obtain good forming results. A flatness based control will be presented to calculate the induced power over time trajectory from a desired trajectory for the temperature in the middle of the billet. The temperature trajectory has to be chosen so that the billet has the desired temperature behaviour. Experimental results will be shown for the flatness based inductive heating of X210CrW12 just below the semi solid state.
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Sabater, Marc, Maria Luisa García-Romeu e Joaquim de Ciurana. "Input Parameters Determination for Predicting Ram Speed and Billet Temperature for the First Billet". Key Engineering Materials 367 (febbraio 2008): 161–68. http://dx.doi.org/10.4028/www.scientific.net/kem.367.161.
Testo completoAbstract (sommario):
The aim of this paper is to present the results of the first step of a defined methodology for the neural network tool development. That first step is to studying the variables that have influence on extrusion process, especially in those that affect billet temperature and extrusion speed. In order to determine those parameters, a preliminary analysis was conducted with experimental data from real industry. Then, a multiple regression analysis was carried out to define which parameters will be the inputs of the neural network prediction tool.