To see the other types of publications on this topic, follow the link: Ingot.
Dissertations / Theses on the topic 'Ingot'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Ingot.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Jennings, Theodore Lee. "Ingot homogenization." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/11240.
Full text
2
Iversen, Fionn. "Meniscus Dynamics in Aluminium Extrusion Ingot Casting." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-527.
Full textAbstract:
In the modern process of continuous Direct Chill (DC) hot top casting of aluminium extrusion ingot with gas slip, poor surface quality of the cast ingot can still be a problem. In the worst cases pronounced surface wrinkling may occur coupled with periodic zones of reduced grain size, macrosegregation and exudation at the surface. The observed surface irregularities are believed to be linked to periodic oscillations or folding of the free molten aluminium surface in the mould, the meniscus, resulting in varying solidification conditions. The focus of this work is to gain a better understanding of the dynamics of the meniscus and the effect it has on ingot surface formation.
3
Jönsson, Johan. "Design Solution for Ingot Handling and Machining." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-85467.
Full textAbstract:
At the electro remelting slag (ESR) facility at Uddeholm, cylindrical steel ingots are produced in several different sizes. The ESR process requires a “starting step” that consist of a 20mm thick steel plate and is a little larger than the diameter of the ingot. During casting the steel plate is inevitably welded to the ingot, also a protective slag layer is also present and flows on top of the melt when the ingot is produced. This layer is sacrificial and is removed before forging. The plate consists of a different and unwanted material composition and must be removed at some point to ensure the best material properties of the ingot. Current process steps at Uddeholm causes the steel plate to be smeared out on the high-quality ingot. The “impure” part of the ingot leads to extra waste and costs after forging. The ingots are cast vertically but needs to be positioned horizontally to be transported to the forge, this is done using an overhead crane and a clamp. This maneuver exerts excessive stress that damages the crane and the clamp sometimes fails and drops the ingot. Because of the high-risk steps during ingot handling as well as the extra waste that is created due to the starting step, the purpose of this thesis is to develop a solution that can: move the ingots from a vertical to a horizontal position in a controlled manner, a method to remove the starting step before forging and reduce the overall risks during ingot handling. The goal is to develop a complete concept that solves the problems mentioned so that the solution can later be realized.To get a deeper understanding of the current procedures and problems, visits and meetings at Uddeholm were carried out. This master thesis builds on the principle of the product development process. Interviews with operators, managers, and other impacted employees at Uddeholm were conducted in order to specify a product specification. To make the project more fathomable, six sub functions were defined. Later a concept generation session using the principles of brainstorming was held with engineers and managers at Uddeholm to find new, plausible solutions to the problems. The results from the session were reviewed and some solutions were discarded directly. Solutions that passed the screening was scored using a weighted decision matrix based on a Kesselring matrix.The chosen concepts were: milling to remove the starting step, “rotary axis grab” to rotate the ingots, a conveyor belt to transport slag, a vacuum and conveyor belt to remove chips, a roll bed with V-pallets to handle and transport the ingots, and let the slag fall of naturally when horizontal. These solutions fulfill almost all of Uddeholm’s requirements and will significantly increase the safety and profitability. The new solutions also bring in high flexibility for production and will free up time for the operators.The lifting tool of the solution needed to be structurally verified to prove it is a valid option. This was done by analyzing the maximum stress in one part of the tool. The results gave that it was indeed a feasible solution.The whole product development process has proven helpful for this machine system. It has especially proven useful for documenting all decisions made throughout the project. This makes it easier for Uddeholm to adopt the solution and develop it further and later realize it.
4
ASUMADU, TABIRI KWAYIE. "MACRO INCLUSION RESEARCH : DETECTION AND EVALUATION OF MACRO INCLUSIONS IN SPECIAL STEELS." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101452.
Full textAbstract:
If these macro inclusions are not detected before the material is put in used, its mechanical properties are greatly affected and this can lead to outrageous consequences in the engineering application.
5
Wu, Yaping. "Numerical analysis of direct-chill casting of aluminum ingot." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=672.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xi, 150 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 86-89).
6
Hintzman, Brian C. (Brian Christopher) 1968. "Capactiy analysis for multi-product, parallel-site aluminum ingot production." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9985.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management; and, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1998.Includes bibliographical references (leaf 76).
by Brian C. Hintzman.
M.S.
7
Lorenz, Michael. "Berechnungsmodelle zur Beschreibung der Interaktion von bewegtem Sägedraht und Ingot." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-130678.
Full textAbstract:
Die vorliegende Arbeit widmet sich der Aufgabe makroskopische Berechnungsmodelle zur Beschreibung des Drahtsägens zu erarbeiten. Ziel ist es, die wesentlichen Effekte abzubilden und den Einfluss von Prozessparametern auf die Dynamik des Systems zu bestimmen. Ein zentraler Punkt ist die Modellierung des bewegten Sägedrahtes. Durch die dem Kontinuum an den Auflagern aufgeprägte Führungsbewegung sind einerseits die Randbedingungen und andererseits ortsfest auf den Draht wirkende Lasten nichtmateriell. Die korrekte kinematische Beschreibung dieses Sachverhaltes ist essentielle Grundlage für die spätere Anwendung des Prinzips von HAMILTON. Durch die Führungsbewegung, die Formulierung der Kontaktkräfte als Folgelasten und durch explizit zeitabhängige Systemparameter ergibt sich ein kompliziertes Systemverhalten. Die dargestellten Berechnungsergebnisse umfassen Studien zu stationären Lagen, die Berechnung von Eigenfrequenzen, Stabilitätsnachweise des dynamischen Grundzustandes, die Bestimmung von Zeitlösungen und die Simulation des Materialabtrages beim EinschnittThe aim of the present thesis is to generate macroscopic models to describe the wire sawing process. The principal purpose is to illustrate basic effects and to investigate the influence of important process parameters relating to the dynamics of the system. A fundamental point is the modeling of the moving wire. Because of the axially movement of the continuum the boundary conditions and spatial acting loads are non-material. The precise kinematical description of this issue is the pre-condition for the correct evaluation of HAMILTON’s principle to characterize the dynamics of the system. The resultant complex system behavior is a consequence of the movement of the wire, of the formulation of the contact forces as follower loads and of explicitly time-dependent model parameters. The results of research contain studies of steady state equilibrium solutions and the proof of their LJAPUNOW stability, the calculation of eigenfrequencies, steady state time solutions under harmonically oscillating contact forces and the simulation of the material removal during the cutting process
8
Kim, Hak Sung. "STUDY ON UNIFORM NEUTRON IRRADIATION FOR SILICON-INGOT IN NEUTRON TRANSMUTATION DOPING." Kyoto University, 2011. http://hdl.handle.net/2433/151902.
Full text
9
Svensson, Jennie. "Plant Experiment Using a Swirl Blade in the Uphill Teeming Process." Thesis, KTH, Materialvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-58923.
Full textAbstract:
The purpose of this thesis has been to evaluate the use of a swirl blade in the uphill teeming process through plant trials. Two series of trials were carried out at Scana Steel Stavanger AS. In the trials a divergent entrance nozzle with a 62° outlet angle were used when casting duplex stainless steel on a base plate with two 6.2 tons ingots. All molds were burned onto the ingots; leading to problems with emptying the ingots from the molds and severe damages on the molds. To get a better insight during the casting and understand why the molds were burned onto the ingots; during the second series of trials one mold on each base plate were filmed in the beginning of the casting process. Evaluation of the castings indicated that splashing on the mold wall at an initial stage was one reason for the mold burned onto the ingot. Further, material samples were collected to evaluate the non-metallic inclusion composition and distribution with SEM when casting with a swirl blade compared to when casting without. The area percentage of the inclusions in the samples was 1% and 2% for samples casted with and without swirl blade respectively with d=2.8 mm. The inclusion size also varied for samples casted with and without swirl blade; 98% of the inclusions were in the size range of 0-10 μm when casted with and in the size range 0-20 μm when casted without swirl blade.Syftet med denna uppsats har varit att utvärdera användningen av swirlblad i götgjutningsprocessen. Två serier med försök har utförts på Scana Steel Stavanger AS. I försöken användes en inloppssten med 62°-vinklat utlopp, där duplexa rostfria stål göts på stigplan med två 6,2 tons kokiller. Alla kokiller brände fast på göten, vilket ledde till svårigheter vid urtag av göten samt skador på kokillerna. För att få en bättre förståelse av varför kokillerna brände fast, filmades ett göt på vardera stigplan under den andra försöksserien. Utvärdering av försöken indikerar att en anledning till att kokillerna brände fast på göten var att det stänkte upp stål på kokillväggen i ett tidigt stadium. Vidare har materialprover samlats in för att utvärdera sammansättningen samt utspridningen av icke-metalliska inneslutningar i SEM då göt gjutits med swirlblad jämfört med utan. Area procenten i proverna var 1% och 2% då proverna gjutits med respektive utan swirlblad, med d=2.8 mm. Även storleken på inneslutningarna i prover som gjutits med och utan swirlblad skiljde sig åt, 98% av inneslutningarna var i storleksintervallet 0-10 μm för prover gjutna med swirlblad medan de som gjutits utan var i storleksintervallet 0-20 μm.
JK24053
10
Ahmed, Shatil S. "Study of deformation processing of Structural Porous Metals." Ohio University / OhioLINK, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1178817532.
Full text
11
Laczik, Z. "Scanning infra-red microscope studies of inhomogeneities in Si and GaAs ingot materials." Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316864.
Full text
12
Brash, Benjamin. "Distortions of Press Quenched Crown Wheels." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170022.
Full textAbstract:
Scania has experienced difficulties with large variations of the slope of the back plane after press quenching of case hardened crown wheels of especially type R780 Steg supplied from ingot cast material. This leads to that a large number of crown wheels has to be remeasured and sorted according to back slope which is time consuming for operators. Also, after sorting of the crown wheels, hard machining has to be adjusted according to the different slopes of the back plane of the crown wheels. In some cases, it also leads to scrapping of the crown wheels.This master’s thesis was divided in two parts. The aim of the first part was to confirm that the crown wheel type and casting technique that exhibits the largest variations in slope of the back plane is the R780 Steg originating from ingot cast material. The crown wheel types that were compared were the R780 Steg, R780 Slät and R885 Slät. Crown wheels manufactured from ingot cast material and from continuous cast material were compared. Hence, 6 combinations were examined. The slope of the back plane was measured with the measuring probe FARO after press quenching. The slope of the crown wheels was found to depend on both casting technique and the geometry of the crown wheel. The results confirmed that the crown wheel type and supplier combination that by far yields the largest variations in slope of the back plane is the R780 Steg supplied by Steel Plant A who uses the ingot casting technique. For this combination the variation exceeds 0,1 mm. All other combinations of crown wheels and suppliers yield acceptable variations.The second part of this master’s thesis was composed of determining if segregations in the cast ingot are the cause of the variations in slope of the back plane of the crown wheel type R780 Steg. This was done by measuring if there is a correlation between the slope of the back plane of the crown wheel after press quenching, the chemical composition and the original position of the crown wheel in the ingot. As in the first part of the study, the distortion was measured by the measuring probe FARO. The samples were sent to Degerfors Laboratorium for chemical analysis. Analyses of C, S and N were made by using combustion analyses. For As, P, B and Al optic spectrometry (spark) was used. All other elements were analysed by x-ray fluorescence. Segregations were found to be present and in combination with the geometry of R780 Steg to be the cause of the large variations in slope of the crown wheels.The results of this thesis show that, for the crown wheel type R780 Steg, Scania should not use suppliers that employ the ingot casting technique. Instead, only suppliers using the continuous casting technique should be used. However, for the other crown wheel types ingot or continuously cast material can be used.
13
Ragnarsson, Lars. "Formation of non-metallic inclusions and the possibility of their removal during ingot casting." Doctoral thesis, KTH, Mikro-modellering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12458.
Full textAbstract:
The present study was carried out to investigate the formation and evolution of non-metallic inclusions during ingot casting. Emphasize have been on understanding the types of inclusions formed and developed through the casting process and on the development of already existing inclusions carried over from the ladle during casting. Industrial experiments carried on at Uddeholm Tooling together with laboratory work and Computational Fluid Dynamics (CFD) simulations. Ingots of 5.8 tons have been sampled and the types of inclusions together with their distribution within the ingot have been characterized. Two new types of inclusions have been found. Type C1 is found originated from casting powder and in the size from a few μm to 30 μm. Type C2 is of macro inclusion type sizing up to 70 μm. The presence of C2 inclusions are few but very detrimental for the quality of the steel. Both types, C1 and C2 consist of alumina, indicating that reoxidation is the main reason for their existence. The protecting argon shroud has been studied by the use of a 1:1 scaled 2D model. Both flow pattern and oxygen measurement have been carried out. CFD has also been used as an auxiliary tool. It has been found that the oxygen pickup through argon gas shroud depends mostly on the distance between the ladle and the collar placed on top of runner. Further increase of gas flow rate above 2.5 m3.h-1 had very little effect on the oxygen distribution since both the flushing effect and the entraining effect with respect to oxygen are enhanced by further increase of inert gas flow rate. In the case of dual gas inlet, the flow in the shroud was found much less diffused compared with either vertical or horizontal injection system. The oxygen content in this arrangement was also greatly reduced. Studies of the runner after casting revealed a sparse non-metallic network structure around the periphery of the steel rod remained in the runner. The surface of the refractory had been severely attacked by the mechanical force from the streaming steel. The erosions of the centre stone and the end stone were on the other hand negligible. CFD calculations showed that the flow at those locations is almost stagnant. The surface of the refractory in contact with the steel was found to have an increased content of alumina. The source for the alumina could come from either exchange reaction of dissolved aluminium replaces the silica or reoxidation products origin from oxygen pick up during the transfer from the ladle to the vertical runner. Inclusions were also found entrapped in the steel refractory interface. It was also found that a formation of a liquid slag film as early as possible during casting would increase the possibility to remove inclusions and especially inclusions generated by the casting powder.QC 20100617
14
Nelson, Stephen Eric 1960. "The geology and mineralization potential of the Bella Vista-Ingot area, Shasta County, California." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/558057.
Full text
15
Doostmohammadi, Hamid. "A Study of Slag/Metal Equilibrium and Inclusion Characteristics during Ladle Treatment and after Ingot Casting." Doctoral thesis, KTH, Materialvetenskap, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11596.
Full textAbstract:
Today, there is a high demand on clean steel for high performance materialproperties. Thus, steel producers try to deliver a steel product with the highestquality and cleanliness to the market. The number of parameters that affect thesteel cleanliness may vary depending on the required material properties of thefinal product. However, the non-metallic inclusion characteristics represent one ofthe most important parameters. More specifically, the composition, size, numberand morphology affect steel cleanliness. In this work, selected parameters affectingthe inclusion characteristics were studied using the following methods: i)thermodynamic calculations (including computational thermodynamiccalculations), ii) inclusion determinations using a cross sectional (CS) method (2Dinvestigations) and iii) inclusion determinations using an electrolytic extraction(EE) method (3D investigations). The computational thermodynamic calculations of the slag-steel and inclusion-steelequilibriums were carried out using the Thermo-Calc software. With the help ofthese calculations, the influence of the slag carryover on the top slag, aluminumcontent in steel and sulfur distribution ratio as well as predictions of stable phasesof inclusions were studied. In addition, inclusion determinations of tool steel gradesamples collected during various stages of the ladle treatment in a scrap-based steelplant were carried out using both 2D and 3D methods. Furthermore, inclusiondeterminations of bearing steel grade samples from a runner system after ingotcasting were performed using a 2D metallographic method (CS-method). Also, theINCAFeature software was used, when using cross sectional method, in order tocollect more statistics of the inclusion characteristics. It was found that slag carryover has a large influence on the composition of theactual top slag as well as the aluminum content in the steel as well as the sulfurdistribution ratio. In addition, steel and slag were found to be in “near”-equilibriumconditions, after the completion of the vacuum degassing operation. Furthermore,the composition of small-size inclusions in samples taken from tool steel was foundto be very scattered. Moreover, the composition of the large-size inclusions wasfound to be less scattered. Furthermore, closer to the top slag composition insamples collected after vacuum degassing. Finally, the accuracy of the inclusioncomposition determinations of tool steel samples using the electrolytic extractionmethod was found to be better than for the cross sectional method. The worseaccuracy of the CS-method is due to a considerable effect of matrix elements oninclusion composition.QC 20100709
16
Granger, D. A. "Structural control in direct-chill (DC) cast aluminium alloy ingot with special reference to architectural applications." Thesis, Brunel University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245434.
Full text
17
Lane, Malcolm D. "A coupled thermal - fluid flow model of the horizontal direct chill casting process for T-ingot." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31593.
Full textAbstract:
In recent years, Horizontal Direct Chill (HDC) casting has gained
popularity as a method for processing primary aluminum. In an attempt to further
develop the knowledge and understanding necessary to enhance HDC casting
capabilities in industry and improve its economic viability, a coupled thermal-fluid
flow model of T-ingot casting has been developed. The model, developed using
the commercial computational fluid dynamics software, ANSYS CFX-10.0,
predicts the temperature and flow fields which occur during aluminum T-ingot
HDC casting under steady-state operational conditions. Buoyancy, turbulence,
solidification effects including flow damping and latent heat release, and boundary
conditions were accounted for using methods that represent the physics occurring
in the industrial process.
Predictions for HDC T-ingot casting of pure and foundry (alloy A356)
aluminum were compared to measurements made on industrially cast ingots. The
measurements conducted included: drained sump profiles (6 in total), secondary
dendrite arm spacings (SDAS), and location of macrostructure features. In all
cases, the predictions matched the measurements well, providing confidence in the
model and the methodology used.
Throughout development of the model, sensitivity to modelling
methodology as well as process and numerical parameters were explored. To
simplify comparison, an extensive analysis was conducted by varying single
features of a baseline model to show the importance of the modelling
methodologies and process parameters.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
18
Safra, Leandro Cesar Pereira Gomes. "Obtenção de fios em ligas de cobre para utilização em linhas de transmissão e em eletrodos para contatos elétricos." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-20122011-165234/.
Full textAbstract:
O objetivo do presente trabalho consistiu no desenvolvimento de fios de liga de cobre-cromo-zircônio (CuCrZr) em uma composição estabelecida em Cu-0,7%Cr- 0,1%Zr (em massa). Nas etapas desenvolvidas, foram feitos botões de cobrecromo (CuCr) e cobre-zircônio (CuZr) em um forno a arco elétrico de eletrodo não consumível, sendo esses botões, posteriormente, fundidos junto com cargas de cobre em um cadinho de alumina (Al2O3) inserido no interior de um vaso de aço inoxidável, que serviu como suporte. Após a fusão dos botões e cargas, o banho foi vazado em uma coquilha de cobre, obtendo-se os tarugos da liga de cobre. Dos tarugos em estado bruto de fusão, foram retiradas amostras para ensaios de dureza Vickers. Nesses tarugos foi feito um tratamento térmico de homogeneização a 910 °C por 2 h. Os tarugos foram posteriormente trabalhados mecanicamente a frio por forjamento rotativo seguido de trefilação, para obtenção final dos fios no calibre de 2,174 mm. Os fios passaram por dois tratamentos térmicos de recristalização, um a 510 °C por 1 h e outro de 480 °C por 5 h. Os fios foram caracterizados mecanicamente por ensaios de tração e de dureza e os resultados foram comparados com dados experimentais da literatura.The objective of this work is the development of copper alloy wire-chromiumzirconium (CuCrZr) in a chemical composition Cu-0,7% Cr-0,1% Zr (weight). The main steps were, buttons were made of copper-chromium (CuCr) and copperzirconium (CuZr) in an electric arc furnace, these buttons were later melted with copper charge in a alumina crucible, placed inside a stainless steel can which served as a support. After melting buttons and charge, the bath was poured into a copper chill mold obtaining copper alloy billets. From the as cast cooper alloy billets, small samples were cut for Vickers hardness and then, a homogenizing heat treatment at 910 °C for 2 h was performed. The billets were then mechanically cold worked by swaging followed by drawing to obtain the wires with a diameter of 2,174 mm. The wires are mechanically characterized using tensile and hardness testing after recrystallization heat treatment at 510 °C for 1 h and at 480 °C for 5 h and the results were compared with experimental data from literature.
19
Yurgel, Charles Chemale. "Efeito da agitação eletromagnética nas propriedades de aços AISI 1025 forjados a quente." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/96296.
Full textAbstract:
Este trabalho tem como objetivo avaliar o efeito do processo de agitação eletromagnética (AE) utilizado no lingotamento contínuo (LC) e nas propriedades mecânicas e metalúrgicas dos aços ABNT 1025 (com adições de manganês e silício) forjados a quente, para a confecção de flanges de tubulações industriais. As matériasprimas fornecidas foram caracterizadas através de composição química e macrografia. Compararam-se os aços provenientes de três condições de fornecimento: 1º) LC sem AE somado à laminação a quente (LQ); 2º) LC com AE; e 3º) LC sem AE. Em seguida, foram extraídos billets de seção quadrada de 120mmx120mmx58mm das três condições citadas para subsequentes forjamentos a quente e fabricação de flanges. Assim, são mostrados os resultados das propriedades obtidas e a comparação com a norma de validação ASTM A 105 (especificação padrão para forjados de aço carbono para aplicação em tubulações) utilizada nesse tipo de forjado. Através da norma, foram verificados os requisitos químicos e ensaios de tração e de dureza. As propriedades foram, também, analisadas através de metalografias (macro e micro), ensaios de impacto e ensaios não destrutivos de líquidos penetrantes. Através da teoria elementar da plasticidade, os valores requeridos para a força de forjamento da peça em estudo, durante o processo de forjamento a quente, foram estimados em caráter formativo e didático. De acordo com os fundamentos teóricos observados na revisão bibliográfica e com os resultados práticos obtidos, constatou-se a aprovação dos aços provenientes do LC com AE como alternativa aos provenientes da LQ (tradicionalmente fornecidos às forjarias) para a confecção de flanges forjados desse tipo de aço. Na análise dos forjados provenientes do LC sem AE também ocorreu a reprovação de diversos resultados, mostrando o efeito da AE como alternativa para as propriedades desse tipo de forjado.The objective of this work is to evaluate the effect of the process of electromagnetic stirring (ES) used in continuous ingot (CI) in the mechanical and metallurgic properties of 1025 ABNT hot forged steels (with the addition of manganese and silicon) for the manufacture of flanges of industrial pipes. At first, the supplied raw materials were characterized trough chemical compound and macrograph. Then, steels from the following three supplying conditions [ 1º) CI without ES plus hot rolling (HR); 2º) CI with ES; and 3º) CI without ES] were compared. Afterwards, billets were extracted from a square section measuring 120mmx120mmx58mm, from the three previous conditions, to be hot forged and to the manufacture of connection flanges. Thus, the results from these properties and the comparison with the validation norm ASTM A 105 (standard specification for steel-carbon forgings for the application in pipes) for this type of forged are shown. Through this norm, chemical requirements, tension and hardness tests were verified. The properties were also analyzed through metallographies (macro and micro), impact tests and non-destructive tests of penetrating liquids. Through the elementary plasticity theory, the demanded values for the forging force of the studied piece, during the hot forging process, were estimated as didactic and formative natures. According to the theoretical substances observed in the bibliography and to these practical results, the steels from CI with ES were approved as an alternative to the ones from HR (traditionally supplied to forging companies) to the manufacture of forged flanges of this type of steel. Moreover, in the analysis of forgings from CI without ES, the disapproval of various results also occurred, showing the effect of ES as an alternative to the properties of this type of forging.
20
Stachel, Suzanne M. "International Nongovernmental Organizations and Development." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1271691749.
Full text
21
Weaver, Donald S. "Thermomechanical Processing of a Gamma-Prime Strengthened Cobalt-Base Superalloy." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543508199900005.
Full text
22
Junk, Margrit. "Material properties of copper alloys containing arsenic, antimony, and bismuth the material of Early Bronze Age ingot torques /." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968751180.
Full text
23
Niu, Shuai Verfasser], Dieter [Akademischer Betreuer] [Senk, Andreas [Akademischer Betreuer] Bührig-Polaczek, and Karl-Hermann [Akademischer Betreuer] Tacke. "Effect of mechanical vibration on ingot solidification / Shuai Niu ; Dieter Georg Senk, Andreas Bührig-Polaczek, Karl-Hermann Tacke." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1194066925/34.
Full text
24
Niu, Shuai [Verfasser], Dieter [Akademischer Betreuer] Senk, Andreas [Akademischer Betreuer] Bührig-Polaczek, and Karl-Hermann [Akademischer Betreuer] Tacke. "Effect of mechanical vibration on ingot solidification / Shuai Niu ; Dieter Georg Senk, Andreas Bührig-Polaczek, Karl-Hermann Tacke." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1194066925/34.
Full text
25
Ghazian, Tafrishi Babak. "Study of Argon Shrouding in Ingot Casting, with Focus on Improving the Operation at Scana Björneborg Steel Plant." Thesis, KTH, Materialvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160530.
Full textAbstract:
This thesis has been carried out as a development project at Scana Steel Björneborg with the purpose to study the influential parameters in argon shrouded ingot casting during the manufacturing of low-alloy steels. In the first stage, a literature study was conducted in order to investigate the theoretical background of the procedure and the importance of protecting the melt during ingot casting. Next, a computer model of the shield was designed using COMSOL Multiphysics® with regard to the process conditions at Scana Steel Björneborg. The effect of various parameters on the process was examined through simulations of the argon gas flow pattern, heat transfer between the gas and the melt stream, and the chemical species transport in the gas around the melt stream. Based on the simulation results, two different shapes of shield were proposed for the argon shrouding operation. A set of implementation tests was executed in order to check the installation and usage conditions of the two new shields. After deciding the proper shape of the shield, a full-scale ingot-casting test was performed with the selected shield to investigate the protection behavior. Moreover, the impact of the new casting-protection shield on the nitrogen and oxygen contents of steel was examined through sampling and analyzing the steel before and after casting. It was found that the use of the new shield during the uphill ingot casting is an effective way to reduce the final nitrogen and oxygen contents of the casted ingot. Therefore, the new design of the shield can be used as a developed substitute for the protection of the melt stream in the ingot casting operation.
26
Tan, Zhe. "Some Aspects of Improving Initial Filling Conditions and Steel Cleanliness by Flow Pattern Control Using a Swirling Flow in the Uphill Teeming Process." Doctoral thesis, KTH, Tillämpad processmetallurgi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-117718.
Full textAbstract:
The flow pattern has widely been recognized to have an impact on the exogenous non-metallic inclusion generation in the gating system and mold flux entrapment in the uphill teeming process. Thus, a well-controlled flow pattern during the teeming process can improve the quality of ingots and further increase the yield during steel production. The current study focused on investigating and optimizing the flow pattern of steel in the gating system and molds to improve steel cleanliness during the initial filling moment. A mathematical model considering a trumpet was initially compared to a reduced model only considering part of the runner channel. Thereafter, the influence of swirl blades implemented at the bottom of the vertical runner on the improvement of initial filling conditions in the molds was investigated in a model considering the entire mold system including a trumpet. The effects of a swirl blade orientation on a swirling flow were further discussed. The simulation results, when utilizing swirl blades, were also verified by plant trials performed at Scana Steel. In addition, a new novel swirling flow generation component, TurboSwirl, was studied in a model considering the entire mold system including a trumpet. The model was based on modifications of the refractory geometry at the elbow of the runners near the mold without the usage of an inserted flow control device in the gating system. Owing to its great potential for improving the flow pattern of steel during the initial filling moment, the effect of TurboSwirl on steel cleanliness was also studied. The results showed that the initial filling conditions during the uphill teeming process can be improved by using a swirl blade or a TurboSwirl in the gating system. This makes it possible to further decrease the initial position of mold powder bags. In addition, it reduces the possibilities of exogenous non-metallic inclusion generation in the gating system as well as mold flux entrapment in the mold during the uphill teeming process. However, the utilization of swirl blades created a considerable amount of droplets when steel entered the molds during the first couple of seconds, which also was verified by the plant trials. The introduction of TurboSwirl showed a greater potential than a swirl blade due to a more evenly distributed swirling flow. The DPM model adopted in the simulations revealed that the TurboSwirl can improve steel cleanliness by increasing the non-metallic inclusion collision rate both with respect to Stokes and turbulent collisions.QC 20130204
27
Xue, Boran. "Heat transfer characterization of secondary cooling in the horizontal direct chill casting process for aluminum alloy re-melt ingot." Thesis, University of British Columbia, 2010. http://hdl.handle.net/2429/26877.
Full textAbstract:
Horizontal direct chill (HDC) casting is a continuous process used to produce extrusion billet and re-melt aluminum ingot. As in vertical DC casting, secondary cooling, where water directly impinges on the cast surface, is an important process that can affect cast quality and production rates. During HDC casting, secondary cooling is further complicated by horizontal water flow and the water spray conditions. Characterizing the heat transfer during the secondary cooling process is necessary for improved understanding of the process. Since the accessibility of the HDC casting machine is limited and the direct measurement of heat transfer in secondary cooling are difficult, numerical modeling thus becomes a good approach for process development.
In this research, the heat transfer occurring in secondary cooling of an HDC ingot has been studied. Water spray conditions on three different casting surface were simulated separately by quenching the blocks of HDC cast A356 aluminum alloy which was cut from a T-ingot. The temperature history during the cooling within the blocks was recorded by sub-surface thermocouples. An inverse heat transfer model was developed and used to calculate the heat fluxes on the casting surfaces using measured temperature data. The heat fluxes were characterized via boiling curves, which are the functions of surface temperatures, in each spray configuration.
The effects of operational parameters, including the casting speed and the water cooling rate, were investigated by comparing the characteristic features of the calculated boiling curves. The spray configuration effect was also studied with the calculated results from the stationary tests in a qualitative fashion.
Then a fitting technique was developed to idealize the calculated boiling curves. The idealized boiling curves were summarized into the functions,
which provide practical database for application of the results in this research.
All in all, the simulation apparatus and the IHC model provide the ability of characterizing the heat transfer occurring in secondary cooling region of HDC casting with lab-scale experiments. Consequently, the expensive and risky plant trials can be avoided.
28
Lorenz, Michael [Verfasser], Alfons [Akademischer Betreuer] Ams, Alfons [Gutachter] Ams, and Jörg [Gutachter] Wauer. "Berechnungsmodelle zur Beschreibung der Interaktion von bewegtem Sägedraht und Ingot / Michael Lorenz ; Gutachter: Alfons Ams, Jörg Wauer ; Betreuer: Alfons Ams." Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://d-nb.info/1220911747/34.
Full text
29
Rappaport, Aviva. "A 12 month randomized control trial assessing the efficacy of an iron ingot to improve hemoglobin concentration in rural Cambodian women." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59496.
Full textAbstract:
Background: Anemia affects 45% of women of reproductive age in Cambodia. Globally, iron deficiency is thought to be the most common cause of anemia. Iron supplementation is recommended in populations where anemia prevalence is high. However, there are issues of cost, distribution and compliance with iron supplementation. A potential alternative is The Lucky Iron Fish® (LIF®), a reusable fish-shaped iron ingot which, when added to the cooking pot, leaches iron into the boiling water or soup in which it is prepared.
Objective: The primary objective of this study was to determine if there was a difference in hemoglobin concentration among rural Cambodian anemic women (18-49 y) cooking with the LIF or a daily iron supplement compared to control after one year.
Methods: In Preah Vihear, 340 women (18-49 y) with mild or moderate anemia (hemoglobin< 80-119 g/L) were randomized to: 1) a LIF group, 2) a daily 18 mg iron supplement group, or 3) a control group. A venous blood sample was taken at baseline, 6 and 12 months. Blood was analyzed for hemoglobin, serum ferritin and serum transferrin receptor (sTfR). Hemoglobin electrophoresis was used to detect structural hemoglobin variants.
Results: During recruitment, anemia prevalence (hemoglobin<120 g/L) was 45% with the HemoCue 301. At baseline, prevalence of iron deficiency anemia differed by biomarker: 9% with serum ferritin (<15μg/L), and 30% with sTfR (>8.3 mg/L).
At endline, the prevalence of anemia was 61%, 67%, and 62% in the LIF, supplement, and control groups, respectively. There was no significant difference in hemoglobin (mean; 95% CI) between the LIF group (116; 113, 118 g/L), iron supplement group (115; 112, 117 g/L), and control group (115; 113, 118 g/L; p=0.897). Serum ferritin was significantly higher in the iron supplement group (97; 88, 105 μg/L; p=0.002) compared to the LIF (78; 69, 83 μg/L) and control groups (76; 71, 85 μg/L).
Conclusions: Our findings show that in this population with a low rate of iron deficiency, the LIF is ineffective at reducing anemia. Our findings suggest that factors other than iron deficiency are likely responsible for the high rate of anemia in Preah Vihear, Cambodia.Land and Food Systems, Faculty of
Graduate
30
Tan, Zhe. "Modeling of Initial Mold Filling in Uphill Teeming Process Considering a Trumpet." Licentiate thesis, KTH, Tillämpad processmetallurgi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-73948.
Full textAbstract:
The flow pattern in the uphill teeming process has been found to be closely related to the quality of ingots and further to affect the yield of ingot production, which is crucial for the steel making process. The formation of non-metallic inclusion and entrapment of mold flux has been considered to be affected by the flow pattern in the gating system and molds by many previous researchers. The aim of this study is to investigate the flow pattern of steel in the gating system and molds during the initial filling stage. In addition, to study the utilization of swirl blade implemented at the bottom of the vertical runner on the improvement of initial filling condition in the mold. A three dimensional model of two molds gating system for 6.2 ton ingots from Scana Steel was adopted in the present work. A reduced geometry model including one mold and a runner, based on the method from previous researchers, was also used for comparison with the current more extensive model. Moreover, a reduced geometry model including one swirl blade and a runner was simulated to find effects of an increased-length vertical runner on the flow pattern improvement at the vertical runner outlet. Flow pattern, hump height and wall shear stress were respectively studied. A reduced geometry with homogenous inlet conditions fails to describe the fluctuating conditions present as the steel enters the mold. However, the trends are very similar when comparing the (hump height-surface height) evolution over time. The implementation of swirl blades gives a chaotic initial filling condition with a considerable amount of droplets being created when steel enters the molds during the first couple of seconds. However, a more calm filling condition with less fluctuation is achieved at the molds after a short while. Moreover, the orientation of the swirl blades affects he flow pattern of the steel. A proper placement of a swirl blade improves the initial filling conditions. The utilization of swirl blades might initially result in larger hump height. However, it gives fewer fluctuations as the casting proceeds. In the model without swirl blades, the maximum wall shear stress fluctuates with a descending trend as the filling proceeds. An implementation of swirl blades can decrease and stabilize the wall shear stress in the gating system. A special attention should be made in choosing refractory at the center stone, the horizontal runner near center stone and the vertical runner at the elbow. This is where the wall shear stress values are highest or where the exposure times are long.QC 20120203
31
Oppitz, Mattias. "Glödskalsrensning på göt med varierande tvärsnitt." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19578.
Full textAbstract:
På Ovako i Hofors, framställs stål via götgjutning. Göten har ett kvadratiskt tvärsnitt som varierar mellan 300 och 700 mm. Dessa transporteras från stålverket, till valsverket för uppvärmning. Varpå de varmvalsas till färdiga ämnen. Under tiden i ugnen när göten värms upp, oxiderar järn och andra legeringar och bildar glödskal. Om glödskalet valsas in i ämnet ger det upphov till defekter, som föroreningar och sprickor, med kvalitetsproblem som följd. Därför var det en önskan från Ovako att ta fram en metod för att rensa glödskal på göt med varierande tvärsnitt. Syftet med examensarbetet var att utreda möjligheterna att avlägsna glödskal från göt, med hjälp av vattentryck eller andra metoder. Olika metoder har utvärderats utifrån tidigare forskning inom området, och utifrån olika värderingar, valdes högtrycksspolning med vatten som metod att gå vidare med. Under höga tryck och flöden sprutas vatten genom dysor, som bryter glödskalet och avlägsnar det från götet. Denna metod är den mest förekommande på de flesta valsverk. Problematiken hos Ovako är att deras göt har varierande tvärsnitt, och utrustningen måste anpassa sig efter dimensionerna. Beräkningar gjordes med värden från befintliga valsverk, och med deras utrustning som klarar av att rensa glödskal på ett tillfredsställande sätt. Ett systemtryck på 25 MPa, med ett totalflöde på nästan 130 l/s levereras genom 44 dysor fördelat på götets fyra sidor. Avståndet mellan dysor och göt är 150 mm, där dysornas stråle har en vinkel på 15 grader mot ytans normal. Detta system ger ett yttryck på 0,92 MPa. Varav yttrycket bör ligga mellan 0,5 och 1,0 MPa för att ge god rensning. Ackumulator bör användas, med en volym på ca 0,35 m3. När götets tvärsnitt ändras vid rensningen, kommer dysramperna att justeras för att alltid ha samma avstånd från dysorna till götet. Slutsatsen av arbetet är att denna metod och utrustning kommer att rensa göt på ett tillfredsställande sätt. Däremot bör utrustningen optimeras, för att passa de olika typerna av stål som tillverkas på Ovako.At Ovako in Hofors, steel is produced through ingot casting. These ingots have a square cross-section, which varies between 300 and 700 mm. These are transported from the steel plant, to a hot-rolling mill for reheating. Whereupon it then gets rolled into finished materials. During the time in the furnaces, when ingots are heated, iron and other alloys oxidize and form a scale. If this scale then is rolled into the material, defects, such as impurity and cracks are formed in the steel, with quality issues as a result. Therefore, it was a desire from Ovako to develop a method to clean the scale on ingots with varying cross-section. The aim of this thesis was to investigate the possibility of removing scale from ingots using high-pressure water or other methods. Various methods have been evaluated on the basis of previous research in the area, and based on different values, water was chosen as a method to proceed with. Under high pressure and flow, water is sprayed through nozzles, which breaks the scale and removes it from the ingot. This method is the most occurring in hot-rolling mills. The problem at Ovako is that their ingots have varying cross-section, and the equipment must adapt to the difference in the dimensions. Calculations were made using values from existing rolling mills and with their equipment that is capable of descale in a satisfactory manner. A system pressure of 25 MPa, with a total flow of almost 130 l/s are delivered through 44 nozzles distributed over the ingots four sides. The nozzle distance to the ingot is 150 mm, where the nozzles have a jet angle of 15 degrees to the surface normal. This system provides a surface pressure of 0,92 MPa. Which should be between 0,5 and 1,0 MPa to give a satisfactory result. Accumulator should be used, with a volume of 0,35 m3. When the ingots cross-section changes during descaling, the spray headers will adapt to have the same distance between nozzles and the ingot. The conclusion of this work, is that this method and equipment will clean ingots in a satisfactory manner. However, the equipment should be optimized to suit the different types of steel, produced in Ovako.
32
Krüger, Thomas. "Entwicklung einer Erregereinheit zur Erzeugung hochfrequenter Schwingungen beim Drahtsägen." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-157218.
Full textAbstract:
Bei der Fertigung von Siliziumwafern durch Zerteilen eines Siliziumblockes kommt das Drahttrennläppverfahren zur Anwendung. Es wird eine Erregereinheit entwickelt, die den Siliziumblock während des Schneidprozesses zu Schwingungen anregt. Die Verwendung von Piezoaktoren ermöglicht mehrachsige Schwingungen mit variabler Frequenz und Amplitude. Wesentliche Bestandteile der Arbeit sind experimentelle Untersuchungen an den Aktoren und der gesamten Erregereinheit sowie die Modellierung des Gesamtsystems mit Hilfe linearer Einzelmodelle. Es zeigt sich, dass die Aktoren bei dynamischen Anwendungen linear beschrieben werden können, während das Gesamtmodell besonders in den Resonanzbereichen aufgrund montagebedingter Einflüsse Schwächen aufweist. Abschließend wird der Einfluss der Schwingungsanregung beim Drahtsägen untersucht. Aus den Versuchen geht hervor, dass im getesteten Frequenz- und Amplitudenbereich sowohl hohe Erregerfrequenzen als auch –amplituden geringere Schnittkräfte zur Folge haben.
33
Gennesson, Marvin. "Étude expérimentale de la mise en place des structures de solidification dans les lingots d'acier." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0278/document.
Full textAbstract:
L’amélioration de la solidification de lingots d’acier industriels de plusieurs tonnes demeure un défi scientifique. Lors de cette étape cruciale, des hétérogénéités chimiques – à l’échelle du mètre – peuvent se développer. Le mouvement des grains solides qui se forment et se déplacent dans le bain liquide est un des leviers d’action sur la macroségrégation. L’inoculation permet d’agir sur le nombre, la taille et la morphologie de ces grains via des ajouts dans le métal liquide. Dans ce travail, les nuances 42CrMo4 et 34Cr4 ont été inoculées pour plusieurs formats de lingots. Des techniques de caractérisation (2D et 3D) ont été développées pour la comparaison des structures de solidification dendritiques avant et après inoculation. Une première série de lingotins (50 g) a montré l’effet affinant de poudres à bonne cohérence cristallographique avec la ferrite et l’effet grossissant d’un ferroalliage de cérium. Après une étude à plus grande échelle (8 kg) pour les meilleurs candidats (poudres de TiN, CeO2, Si3N4 et ferroalliage de cérium), un ajout de cérium a été fait dans un lingot industriel de 6,2 t. Le cérium, responsable de la croissance des grains équiaxes pour l’ensemble des lingots caractérisés. Il agit probablement sur les tensions interfaciales solide/liquide et moule/liquide tout en remplaçant les sites de germination nativement présents dans le métal liquide par des inclusions au cérium qui ne servent pas de sites de germinationImproving the solidification of large industrial steel ingots remains a scientific challenge. During casting chemical heterogeneities (macrosegregation), sometimes in the scale of meters, can arise. Solid grain motion is one phenomena responsible for macrosegregation. Inoculation allows the number, size and morphology of these grains to be modified through additions to the liquid metal. In this work 42CrMo4 and 34Cr4 grade steel ingots of several sizes were modified with potential inoculants. Characterization techniques (2D and 3D) were developed to compare dendritic solidification structures before and after inoculation. The first series of small ingots (50 g) showed grain refinement for powder additions with a low lattice misfit between the inoculant and solidifying melt, and a coarsening effect when ferrocerium was added. The best inoculant candidates (TiN, CeO2, Si3N4 powders and cerium ferroalloy) were tested in medium sized ingots, after which the cerium addition was tested with a 6,2 t industrial ingot. Cerium is responsible for coarsening the grain size in all sizes of cast ingots investigated. This is likely due to a modification of the solid/liquid and liquid/mold interfacial energy along with the replacement of existing sites with cerium inclusions which are not active during nucleation
34
Zhang, Xiaohuan Verfasser], Dieter [Akademischer Betreuer] [Senk, Bernhard [Akademischer Betreuer] Peters, and Yanping [Akademischer Betreuer] Bao. "Investigation of Mould Filling and Solidification during Ingot Casting Process with Experiments and OpenFOAM Numerical Modelling / Xiaohuan Zhang ; Dieter Senk, Bernhard Peters, Yanping Bao." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1125973234/34.
Full text
35
Zhang, Xiaohuan [Verfasser], Dieter [Akademischer Betreuer] Senk, Bernhard [Akademischer Betreuer] Peters, and Yanping [Akademischer Betreuer] Bao. "Investigation of Mould Filling and Solidification during Ingot Casting Process with Experiments and OpenFOAM Numerical Modelling / Xiaohuan Zhang ; Dieter Senk, Bernhard Peters, Yanping Bao." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1125973234/34.
Full text
36
Mutsakatira, Innocent. "The effect of the surface condition of Aluminium ingot (AA3003) during roll bonding with clad Aluminium alloy (AA4045) to form an Aluminium brazing material." Master's thesis, Faculty of Engineering and the Built Environment, 2021. http://hdl.handle.net/11427/32875.
Full textAbstract:
Hulamin is the leading producer of aluminium products in South Africa. One of the products made at Hulamin is the aluminium brazing sheet. The aluminium brazing sheet is made from two aluminium alloys, AA3003 and AA4045. The main alloying element in the 3XXX series alloy is manganese and the main alloying element in the 4XXX series alloy is silicon. An aluminium brazing sheet is manufactured during an industrial process called “accumulative roll bonding”, where AA4045 is termed “the clad” and AA3003 “the core”. The two materials are stacked together with the core sandwiched between two clad layers. Before the materials are stacked together, they undergo surface preparation. At Hulamin, the surface roughness of the core is kept at 10 µm and the surface roughness of the clad at 1 µm. After surface preparation, the stacked material is put into a hot rolling mill, where it undergoes reduction through several passes until it reaches the desired gauge. The aim of this project is to determine the effect of the surface roughness of both the clad and the core on the quality of the bond after roll bonding. While the relevant literature specifies that an increase in surface roughness increases bond strength, the current set surface finishes being implemented at Hulamin have been obtained through trial and error, with no validated experimental work to support them. This research aims to find the optimum surface finish in order to streamline the process of surface preparation. A design matrix was constructed based on the surface finish being used at Hulamin, where the core was at 10 µm and the clad at 1 µm. Fourteen surface conditions were formulated and three tests were performed on each surface condition. The samples were manually ground on different grit papers to an average surface roughness of 0.5 µm, 1 µm and 3 µm for the clad and 7 µm, 10 µm, 15 µm and 25 µm for the core. Simulation of the hot rolling at the University of Cape Town's (UCT's) Centre for Materials Engineering (CME) laboratory was achieved using plane strain compression testing (PSC) on the Gleeble 3800. The PSC sample geometry of 30 mm x 50 mm x 10 mm was achieved by stacking a 5 mm sample from the clad liner plate and a 5 mm thick sample from the as-cast core material. To simulate the hot roll bonding the tests were run at 450 ºC at a strain rate of 1.5 s-1 . The test parameters were obtained from the Hulamin mill log data. In order to assess the strength of the bond, post PSC test, tensile shear testing was performed on specimens wire-cut from the gauge of the deformed PSC sample. The tensile shear specimens were designed according to ASTM D3165. The tensile shear tests were performed on a Zwick Universal Testing machine, in conjuction with single-camera Digital Image Correllation (DIC). The purpose of the DIC was to monitor the strain localisation at the interface. The tensile test was run at 0.0012 mm/min at room temperature. The shear test results confirmed that surface roughness played a major role in the bond strength formed between these two dissimilar materials. It was found that the Hulamin benchmark surface preparation, set at 10 µm and 1µm, could be improved by increasing the surface roughness of the core to 15µm while keeping the clad surface finish constant. The rolling direction (RD) of the specimen was cut, mounted and polished for microstructural feature characterisation, using light microscopy and scanning electron microscopy (SEM) with backscattered electron (BE) imaging. In order to characterise the bond further, energydispersive X-ray spectroscopy (EDS) was performed across the interface of the samples to show the diffusion of Si. Microstructural analysis revealed that a poor bond resulted in the presence of large voids, while a high integrity metalurgical bond contained very small voids. Also, a good metallurgical bond allowed for the diffusion of Si across the bond, although these results were qualitative because diffusion of Si across the interface is largely time- and temperature-dependent. Combined strain and microstructural results showed that finer surface roughnesses yielded poorer bonds because of minimal frictional force and that rougher surface finishes also yielded poorer bonds, owing to larger troughs on the surface of the material that led to void formation at the interfaces, which in turn caused sites of delamination. There had to be an optimum surface finish that existed between the two alloys where the finish would obtain a metallurgical bond that was of optimum strength. Should this optimum finish be exceeded, the strain level would inevitably increase during tensile shear testing, with the induced voids increasing in size and Si diffusion across the interface decreasing, thereby indicating a compromise in the quality of the bond. It was found that the Hulamin benchmark surface preparation, set at 10 µm and 1µm, could be improved by increasing the surface roughness of the core to 15µm while keeping the clad surface finish constant. The findings of this research could be of significant value to Hulamin in the improvement of the quality and cost of the end product under consideration.
37
Sobotka, Petr. "Vady a vlastnosti masivních odlitků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230127.
Full textAbstract:
A diploma thesis was objected to a figure analyzing and a figure interpretation of ingot processing. The described figures were obtained from samples which were taking from feeder-heads of ingot of lower ram, produced in Vitkovice Machinery Group. The thesis was focused on ingot solidification and segregation processes which were associated with this procedure. The figures obtained from numeric simulation of ingot solidification in defined places were analyzed using statistic method – linear regression, as well as linear regression was used for evaluation of explored samples, their chemical compositions and mechanical properties. In conclusion all acquired results were summarized.
38
Jakubčíková, Lucie. "Návrh technologie a ověření výroby malých ocelových ingotů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401512.
Full textAbstract:
The thesis deals with the design of ingots from duplex (austenitic-ferritic) stainless steels in terms of minimal occurrence of axial porosity. The optimal shape and dimension of the ingot and the casting conditions are determined based on numerical simulations. The resulting internal quality of the realized ingot is evaluated. The presence of shrinkage porosity is determined by penetrant testing. The degree of chemical heterogeneity, the extent of macrosegregation, of selected elements in given ingot locations is measured by an optical emission spectrometer. Segregation values are compared with simulation results. The micro-purity of the ingot is assessed on the basis of metallographic samples.
39
Roch, François. "Modélisation de la solidification d'un lingot de forge." Vandoeuvre-les-Nancy, INPL, 1992. http://docnum.univ-lorraine.fr/public/INPL_T_1992_ROCH_F.pdf.
Full textAbstract:
Des hétérogénéités chimiques se développent pendant la solidification d'un alliage du fait des phénomènes de transport de soluté. Un modèle prenant en compte les phénomènes de transport de chaleur, de masse et de quantité de mouvement lors de la solidification d'un alliage à plusieurs constituants est présenté. Des exemples illustrent les capacités et les limites d'une telle approche pour la prédiction des ségrégations dans un lingot d'acier
40
Bursík, Miroslav. "Otočný zvedací stůl QHZ 20." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229984.
Full textAbstract:
This master’s thesis deals with the design of the new concept of lifting turntable QHZ 20. The main objective is to reduce the installation depth of table. Part of thesis is background research of individual components of the forging complex with hydraulic press CKW 25. It describes the current structure QHZ table, comparing the advantages and disadvantages of possible solutions of the table. The work also includes design, description and calculation of the chosen solution.
41
Olofsson, Anders. "Hardening Distortions of Serial Produced Gears." Licentiate thesis, KTH, Skolan för industriell teknik och management (ITM), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207087.
Full textAbstract:
Hardening distortions are unwanted changes in shape and dimension that arise during hardening of steel components. Uncontrolled distortions induce random errors to the manufacturing process, and have a strong negative impact on manufacturing costs. The distortions are not only caused by the hardening process, several factors from previous manufacturing steps including the component geometry itself contribute to varying extent. The aim of the current work is to investigate the main influencing factors on hardening distortions for serial produced gears. The investigations were done on two different types of gears for heavy-duty transmissions, crown wheels for the rear axle central gear and main shaft gears for the gearbox. The steel was produced using either continuous casting or ingot casting. For rectangular continuously cast steel, the effect of disabling magnetic stirring of the steel melt during casting was investigated, finding a strong reduction of gear runout for crown wheels. Segregations in crown wheels produced from the top and bottom of ingots were shown to go in opposite directions, producing opposite back-face tilts. For crown wheels quenched one at a time, influences of stacking level on the hardening tray were found, indicating an impact from small variations in the carburizing process, despite identical quenching conditions. For main shaft gears, horizontal loading gave considerably less roundness and runout errors but increased flatness errors compared to vertical loading. This thesis shows the complexity of the distortion phenomenon and how several factors interact and contribute to the final result. It is shown that factors with significant impact on hardening distortions for one component may be less important for another component. With this in mind, each type of component to be hardened should be produced by a manufacturing chain where each process step is carefully chosen with respect to minimizing distortions.QC 20170516
42
Koshikawa, Takao. "Deformation of steel ingots by punch pressing during their solidification. Numerical modelling and experimental validation of induced hot cracking and macrosegregation phenomena." Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM027/document.
Full textAbstract:
Ces travaux portent sur la déformation des aciers au cours de leur solidification, au moyen d'une expérience instrumentée et de sa simulation numérique. L'étude est focalisée sur deux phénomènes induits par la déformation : la fissuration à chaud et la macroségrégation. L'expérience consiste à poinçonner latéralement un lingot de 450 kg, alors que son cœur est encore partiellement liquide.L'expérience est instrumentée thermiquement et mécaniquement. Les lingots sont analysés, visuellement en termes de lieu et de fréquence d'apparition de fissures, et par microsonde pour les ségrégations chimiques.Pour la fissuration à chaud, une simulation numérique 3D par éléments finis est mise en œuvre avec le logiciel Thercast®, dans lequel a été implanté un critère d'amorçage de fissure basé sur la déformation plastique cumulée en fin de solidification, entre deux valeurs critiques de fraction de liquide. La comparaison entre simulations et observations montre le caractère prédictif du critère.La simulation numérique de la macroségré-gation est réalisée avec le logiciel R2sol qui résout simultanément la déformation du solide et l'écoulement du liquide. La simulation montre la redistribution des solutés dans le cœur du lingot sous l'effet de la compression du squelette solide et de l'écoulement du liquide, induits par le poinçonnement. Elle reproduit qualitativement les mesures expéri-mentales mais sous-estime l'amplitude des hétérogénéités de composition chimique. Une discussion des résultats permet de dégager des pistes permettant d'espérer une prédiction quantitative dans le futur.Les deux thématiques étudiées ont mis en relief la nécessité d'une bonne modélisation des phénomènes de microségrégation des alliages multiconstitués. Un modèle a été spécifiquement développé à cet effetExperimental and numerical studies of hot tearing and macrosegregation formation during steel solidification are reported. On one hand, an ingot punching test is considered. It consists of the application of a deformation at the surface of a solidifying 450 kg steel ingot. On the other hand, finite element thermo-mechanical modelling of the test is used.For hot tearing analysis, 3D finite element modeling is applied by use of Thercast® software. The time evolution of the strain tensor serves to evaluate the possibility for hot tear formation with a Hot Tearing Criterion (HTC). The HTC compares the local accumulation of strain over a certain solidification interval with the expression of a critical value proposed in the literature. Detailed comparisons reveal an excellent capability of the HTC to predict the formation of hot tears.For macrosegregation analysis, a two-phase formulation has been implemented (R2sol software), in which the velocities of the liquid and solid phases are concurrently solved for. The simulation shows how solutes are redistributed through the central mushy zone of the ingot under the effect of the com-pression of the solid phase resulting from the punching of the solid shell. The simulation proves its capability to reproduce the main experimental trends. However the predicted intensity of macrosegregation is lower than measured. Through discussion and analysis of different numerical sensitivity tests, critical material parameters and model improvements are identified in view of achieving better quantitative predictions in the future.The two topics studied have clearly shown the need for a good modelling of microsegregation phenomena in multicomponent alloys. A numerical model has especially been developed and implemented in the two software packages
43
Pickering, Edward John. "Macrosegregation in steel ingots." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708651.
Full text
44
Thomas, Brian Gordon. "Investigation of panel crack formation in steel ingots using mathematical and physical models." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25980.
Full textAbstract:
An investigation of panel crack formation in steel ingots was undertaken
to improve understanding of the mechanisms by which they develop and to evaluate possible solutions to the problem. The investigation revealed that two distinct types of panel cracks, both of which are partly caused by intermediate-temperature embrittlement of steel involving aluminum nitride precipitation, operate under different mechanisms. Isothermal, physical modelling experiments were conducted to determine the flow patterns, velocity profiles and flame geometry in a bottom-fired soaking pit and the resultant effects on heat transfer. An investigation involving comparison with analytical solutions determined the optimum numerical method to employ for the mathematical modelling of complex, two-dimensional, transient, heat-conduction problems. This method was formulated to calculate the temperature distribution in a steel ingot during the various processing stages from initial casting up to rolling and was verified with industrial measurements. A transient, elasto-visco-plastic, thermal-stress model employing the finite-element method was formulated, developed and verified using analytical solutions. Based on the temperatures calculated by the finite-element, heat-transfer model as input data, the transient, internal stress state of the ingot was calculated, taking into account the effects of phase-transformation volume changes and kinetics, creep, and temperature-dependent mechanical property behavior. The simulated stress histories were found to be directly linked to the progress of the phase-transformation front and were used to clarify the role of stress generation in panel crack formation. Finally, the results of a metallurgical investigation of steel ingot samples containing off-corner panel cracks were synthesized with the results of the physical and mathematical models to determine mechanisms and to suggest solutions for the formation of both mid-face and off-corner panel cracks. Mid-face panel cracks are apparently formed during air cooling when the mid-face surface is between the Ar₁ and 500 °C. Off-corner panel cracks appear to initiate internally during the early stages of reheating, but do not propagate to the surface until air cooling after removal from the soaking pit.Applied Science, Faculty of
Mining Engineering, Keevil Institute of
Graduate
45
Riber, Stéphanie. "Méthodes numériques pour la simulation des écoulements de matériaux granulaires par une approche continue." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEM020/document.
Full textAbstract:
Cette thèse traite de la modélisation et des méthodes numériques pour la simulation d'écoulements de fluides non-Newtoniens, et particulièrement, de matériaux granulaires. Une application de ce travail concerne les poudres de couverture utilisées pour protéger thermiquement le métal de l'air dans le procédé de coulée en source d'alliages métalliques. Ces poudres sont conditionnées dans des sacs disposés dans la lingotière, qui brûlent suite aux fortes chaleurs engendrées, et permettant son écoulement sur la surface du métal. Ainsi, la simulation numérique apparaît comme un puissant outil pour l'optimisation du procédé, et notamment, de l'étalement de ces poudres.Dans ce travail, une formulation éléments finis a été proposée pour modéliser l'écoulement multiphasique des matériaux granulaires dans un formalisme de la mécanique des milieux continus. Les équations associées sont résolues via des schémas numériques stabilisés, couplés avec la méthode Level-Set pour capturer et suivre le profil du matériau granulaire au cours de la simulation. Dans un premier temps, les outils numériques ont été testés sur des cas d'écoulements de fluides de Bingham, où les fortes non-linéarités sont traitées par une méthode de régularisation. Puis la formulation est étendue aux écoulements de granulaires secs, dont le comportement piezzo-dépendent est traduit par la loi mu(I). Le modèle a été validé sur des cas d'effondrement de colonnes de grains, et une étude de sensibilité aux conditions aux limites et constantes physiques du modèle est proposée.Enfin, des cas industriels de chutes de poudres sur substrats solide et métal fondu ont été menés, amenant à des premières pistes pour l'optimisation du procédé de coulée en lingotièreThis thesis is devoted to the modeling and numerical methods for the simulation of non-Newtonian flows, and focuses particularly on granular materials flows. This work is applied to molten powders aiming to ensure metal thermal protection from the air in ingot casting process of metallic alloys. These powders are conditionned into bags disposed into the mold, which burn due to high temperatures, and allowing the powder spreading onto the metal surface. Thus, numerical simulation appears as a powerful tool for the process optimization, and especially, for the powder spreading.In this work, a finite element formulation has been proposed for the modeling of granular multiphase flows, by a continuum approach. The associated equations are solved using stabilized numerical schemes, coupled with the Level-Set method to capture and follow the granular profile during the simulation. First, the numerical tools have been implemented for Bingham flows, by using regularization a method. Then, the formulation was extended to dry granular flows, by the use of the mu(I) rheology constitutive model for describing its pressure-dependent behavior. The model has been validated on granular collapses, and a sensitivity analysis to boundary conditions and physical constants has been proposed.Finally, industrial cases of powder chutes ontoboth solid and liquid metla substrates have been conducted, leading to preliminary solutions for the optimization of ingot casting process
46
Dratnal, Lukáš. "Analýza vad typu nekovových vměstků v odlitcích hlav motorů a návrh metod jejich odstranění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241731.
Full textAbstract:
Improving the quality of metal castings for serial production of automotive industry, leading to improvements in the properties of casts and their lower costs. This publication analyzes the non-metallic inclusions contained in casts of heads of internal combustion engines, molded of Nemak Czech Republic, Ltd. Tackling includes analysis of size, shape, chemical composition and hardness of the specific non-metallic inclusions. The thesis describes the purity metal holding furnaces and proposals to eliminate inclusions from metal.
47
Jones, Michael Rice. "Oxhide ingots, copper production, and the mediterranean trade in copper and other metals in the bronze age." Texas A&M University, 2003. http://hdl.handle.net/1969.1/5957.
Full textAbstract:
The production and trade in copper and bronze was one of the major features of the
complex societies in the Near East and Mediterranean during the third to first
millennia B.C. While finished metal objects are common finds from the period,
ancient metal ingots and hoards of scrap metal, as well as archaeological evidence of
metallurgical activities, are often more important sources of information for how
ancient technology and trade functioned. Shipwrecks, particularly those found off the
coast of Turkey at Uluburun and Cape Gelidonya, as well as mining and smelting sites
in the Mediterranean region, provide invaluable information on the production and
trade of copper and tin, the main ingredients of bronze. In this thesis, I examine the
evolution of the copper trade in the eastern and central Mediterranean, particularly
during the Late Bronze Age, when âÂÂoxhideâ ingots were widely exported. Finds of
oxhide ingots have increased dramatically in recent years, and no synthesis of all of
this newly available evidence is currently available. I attempt to analyze this new
evidence in relation to older finds and research, with a particular focus on the cargo of
the Uluburun shipwreck, the largest collection of Bronze Age metal ingots from a
single site in the Mediterranean. The history of oxhide ingot production is complex,
but by the Late Bronze Age Cyprus was supplying much of the copper used to
neighboring regions, with revolutionary effects on societies in Cyprus and elsewhere. The archaeological evidence shows that oxhide ingots are early examples of a
standardized industrial product made for export by emerging state-level societies
during the second millennium B.C. and fueled the development of international trade,
metallurgical technology, and complex social institutions in a variety of Mediterranean
societies from Egypt and the Levant, Greece, Cyprus, to Sardinia in the central
Mediterranean.
48
Holmkvist, Sandra, and Lina Lidström. "Av inget, kommer inget? : Hur förändras revisionspraktiken och vad beror det på?" Thesis, Umeå University, Umeå School of Business, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-34910.
Full text
49
Almqvist, Johan, and Martin Holmgren. "Inget förtroende, Inget köp : En studie hur förtroendet för influencers påverkar konsumtionsvanor." Thesis, Södertörns högskola, Företagsekonomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-38629.
Full textAbstract:
Within today's society, social media has grown to become a more common thing than most. In Sweden, almost 83 % of the population use social media. With this marketing growth, a role that have become more common is the term ‘influencer’. Whereas an influencer is someone who inspires people in any sort of way by using social media platforms, such as Instagram. The marketing strategy that has evolved through influencers is called ‘influencers marketing’ and is a commonly used marketing strategy in today’s reality. However, the question that companies must ask themselves is - How will this affect consumers? By studying how ‘influencer marketing’ affect consumers whom all follow influencers on Instagram - this study presents which factors have a more deciding role when it comes to being affected by influencer marketing. Whereof we have had several semi-qualitative interviews regarding questions such as; how trustworthy a person finds influencers and if influencer marketing affects a person's consumer behaviour. The results of this study show that consumers feel a certain trust to influencers whereof this study presents 4 factors that affects an individual's ‘trust’. The result showed for example that a person value, genuity and personal connection to an influencer. The trust that an individual has towards influencers showed to have a direct connection to consumer behaviour.I dagens samhälle har sociala medier växt fram och blivit allt vanligare. Hela 83% av internetanvändarna i Sverige använder sig av sociala medier (Karlsson 2018). En roll som har uppmärksammats på sociala medier är begreppet influencer. En influencer är en person som via sina sociala medier kan påverka och inspirera andra människor. Varav denna studie fokuserar på sociala medie-plattformen Instagram. Begreppet influencer är dock något som en stor mängd människor inte vet om vad det betyder (Kádekova & Holienčinová 2018). Detta är ett problem för framförallt företag som vill använda sig av influencer marketing. Problemet ligger i att det är svårt att veta vilken genomslagskraft en influencer har på konsumenterna. Denna studie ämnar därför att undersöka om en konsument känner förtroende för influencers samt om de påverkar en individs konsumtionsvanor. Denna studie är av den kvalitativa forskningsansatsen eftersom det är känslor och upplevelser som studerats. Därav valdes det att utföra semistrukturerade intervjuer för att få djupgående svar från respondenterna. Intervjuerna utfördes på 12 stycken respondenter som alla är mellan åldrarna 18–25 år. Åldersspannet är en medveten avgränsning då tidigare forskning visar på att influencers har mest påverkan på dessa åldrar. Svaren från intervjuerna är den data som används i undersökningen, det vill säga ingen sekundärdata har tagits i beaktning vid resultatet. Resultatet inom studien visade att konsumenter känner förtroende för influencers och studien har kommit fram till ett antal faktorer som bidrar till förtroende. Bland annat att en influencer visar genuinitet eller att en konsument känner en personlig anknytning till influencern. Det förtroende en konsument har för en influencer visade sig ha en direkt påverkan på en individs konsumtionsvanor.
50
Hallén, Björn, and Beatrice Ulfvin. "Utan operatörer inget samband." Thesis, Högskolan i Halmstad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-36999.
Full textAbstract:
Nästan varje organisation är beroende av sina anställda i någon form t.ex. deras kompetens, att det finns tillräckligt många för att lösa organisationens uppgifter eller att de trivs och utför de uppgifter de är ålagda att lösa. Personalen identifieras ofta därför som en nyckelkompetens, bland de viktigaste av en organisations resurser. Detta gäller även inom Sveriges Försvarsmakt. År 2010 ändrades förutsättningarna för Försvarsmakten avseende hur att personalförsörja organisationen. Det gamla personalförsörjningssystemet var baserat på en pliktlag, där personer var tvungna enligt lag att tjänstgöra en begränsad tid inom Försvarsmakten. Detta ersattes av ett frivilligbaserat personalförsörjningssystem. Det går ut på att att all personal är frivilligt anställda, de söker jobb hos Försvarsmakten som soldat eller sjöman. Nu, åtta år senare, är det intressant att ta reda på hur det går. Syftet med denna uppsats är att belysa vilka delar i empirin (kategorier) som skapar bidragande faktorer till den ansträngda bemanningssituationen för sambandsoperatörer inom flottan idag. Detta sker genom att i studien söka efter faktorer som har en påverkan på nu rådande situation och vad som kan förändras för att eventuellt göra tjänsten inom flottans sambandsorganisation mer attraktiv. Både för dem som redan är anställda och för dem som ännu ej är anställda. Detta sker genom att med personintervjuer bygga empiri kring frågeställningen och med kvalitativ dataanalys söka efter faktorer kopplat till denna. Resultatet visar på flera faktorer som huvudsakligen har sitt ursprung inom organisationsteorin. Några exempel av dessa är: informationsspridningen överlag inom organisationen ofta uppfattas som seg, ibland otydlig och motsägelsefull. de administrativa uppgifterna som åläggs mellancheferna tar upp alldeles för stort fokus från mellanchefernas huvuduppgifter. den begreppsförvirring som uppstått inom organisationen i samband med systemskiftet gör att det är svårt att hålla reda på vem som behöver komplettera med vilken utbildning för att passa in “i det nya”. Slutligen för vi en diskussion om huruvida resultatet av studien kan visa på att Försvarsmakten troligen underskattat svårigheterna med övergången från plikt-till frivilligsystem. Det arbete som krävdes inom organisationen för att anpassa sig och förbereda en sådan övergång blev genomfört under stor tidspress och organisationen lever med bieffekterna av det än idag.