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1
Knox, E. "Improved property control of hot rolled carbon manganese steel grades." Thesis, Swansea University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637816.
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The work is in the form of a project aimed at furthering the understanding of metallurgical interactions during the processing of hot rolled CMn (-Si) steel grades. The aim has been achieved through a number of complimentary investigations. Through-coil mechanical testing and metallographic examination, coupled with detailed analyses of relevant process parameters, have highlighted the typical properties and property variations within Corus' CMn (-Si) products. Deformation dilatometry experiments have allowed the transformation behaviour of CMn (-Si) compositions to be assessed and compared with that predicted by transformation theory. Laboratory-scale rolling and cooling experiments have demonstrated the effects of composition and process variations on steel properties. These combined discoveries have contributed to a deeper understanding of the metallurgy of CMn (-Si) steel manufacture. The project has illustrated where product design changes can contribute to enhanced properties, helping Corus to ensure the long-term success of its CMn (-Si) steels within the automotive market.
2
Richardson, Andrew David. "Efficient simulation of cooling processes for hot-rolled steel sections." Thesis, Teesside University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411293.
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Nilsonthi, Thanasak. "Caractérisation Physico-chimique et adhérence de couches d'oxydes thermiques sur des aciers recyclés." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00947653.
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.L'objectif de cette étude était, en premier lieu, de mettre en place en Thaïlande un testd'adhésion par traction-écaillage sur une machine de traction classique (test" macroscopique "), de le comparer au test " microscopique " Grenoblois fonctionnant dansla chambre du MEB et de l'utiliser pour évaluer l'adhérence des calamines de process sur desaciers industriels. Deux paramètres ont été étudiés, la vitesse de déformation et la teneur desaciers en silicium. Il apparaît que l'écaillage des calamines au cours du test augmente quandaugmente la vitesse de déformation. Une vitesse de déformation élevée entraîne unedéformation au premier écaillage plus faible, donc une adhérence mesurée plus faible. Ceteffet est lié aux phénomènes de relaxation. On a pu alors montrer que la présence d'oxyde(s)contenant Si, situé(s) à l'interface avec le métal, augmentait l'adhérence. Les étudesd'oxydation dans la vapeur d'eau qui ont aussi été réalisées ont révélé que la présence desilicium réduisait la vitesse d'oxydation. En augmentant la teneur en Si, les couches defayalite et de wüstite s'épaississent ; par contre, les couches externes s'amincissent. Pour lesaciers contenant du cuivre, la vitesse d'oxydation est réduite quand la teneur en Cu estaugmentée. De la même façon, les couches internes sont plus épaisses et on observe uneaugmentation du nombre de précipités de Cu quand la teneur en cet élément augmente.
4
Stalker, Iain Duncan. "Knowledge modelling for the design of hot rolled steel section roll sets." Thesis, Teesside University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.521872.
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Du, Jinlong. "Development of high strength hot rolled strip steel products with bainitic microstructures." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6881/.
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High strength, low alloy, hot rolled strip steels with yield stresses in the range 700 to 1300MPa are required for the Lifting and Excavating product sector. Improved combination of strength and toughness in these high strength steels is desired, requiring a detailed understanding of the relationship between microstructure and mechanical properties. In this work 12mm thick 700MPa yield stress strip steels with fully bainitic microstructures, with different compositions and/or processing conditions, have been studied. The microstructures of the steels were investigated with both optical microscopy and SEM. Micro-hardness and Charpy impact tests (at different temperatures) were carried out to investigate the mechanical properties, followed up with fracture surface analysis and unit crack path (UCP) analysis. Three types of bainitic microstructures were identified and quantified, including upper bainite, lower bainite and granular bainite. The fracture surface and UCP analysis indicating that granular bainite is detrimental to toughness, but cannot necessarily be avoided in the steels investigated; while the presence of a small amount of lower bainite (above 5%) was found to improve the impact toughness significantly. Continuous cooling transformation (CCT) diagrams for steels with different compositions were produced, which allowed investigation of the phase transformation behaviour and selection of optimum chemical composition/coiling temperature for improved properties. The effects of alloying elements (B, Mo and V) on the transformation behaviour have been confirmed through the experiments. An optimised combination of alloying and coiling temperature has been proposed and validated via investigating plant trial products with similar alloying and processing parameters.
6
Glover, Carol. "Thin organic coatings for hot dip galvanised steel and cold rolled products." Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42838.
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Al-Shihri, Marai Abdullah 1958. "BUCKLING STRENGTH OF HEAVY STEEL COLUMNS (WELDED SHAPES, INITIAL CURVED COLUMNS, HOT-ROLLED SHAPES)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291869.
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Tepe, Bulent. "Evaluation of pre-treatment and powder paint process for hot rolled steel (HRS)." Thesis, Ulster University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516518.
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Bryant, Cameron L. "Web crippling of hot-rolled beams at stiffened-seat connections." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12052009-020154/.
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Yousaf, Naeem. "Calucaltion of waste heat from hot rolled steel coils at SSAB and its recovery." Thesis, Högskolan Dalarna, Maskinteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:du-4516.
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Hot rolling process is heat input process. The heat energy in hot rolled steel coils can be utilized. At SSAB Strip Product Borlänge when the hot rolled steel coils came out of the hot rolling mill they are at the temperature range of 500°C to 800°C. Heat energy contained by the one hot rolled steel coil is about 1981Kwh whereas the total heat energy for the year 2008 is 230 GWh/year.The potential of heat is too much but the heat dissipation rate is too slow. Different factors on which heat dissipation rate depends are discussed.Three suggestions are proposed to collect the waste heat from hot rolled steel coils.The 2nd proposal in which water basin is suggested would help not only to collect the waste heat but to decrease in the cooling time.
11
Zhou, Zhongqing. "Flatness control of hot rolled steel strip during cooling on the run-out table." Monash University, School of Physics and Materials Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9489.
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Allam, Tarek [Verfasser], Wolfgang [Akademischer Betreuer] Bleck, and Brita Daniela [Akademischer Betreuer] Zander. "Direct hot rolled dual phase weathering steel / Tarek Allam ; Wolfgang Bleck, Brita Daniela Zander." Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1127051385/34.
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Phadke, Sameer Arvind. "Modeling microstructural evolution and phase transformation for optimized properties of hot rolled steel products." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1302108216.
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Debray, Bruno. "Microstructure and mechanical properties of an as-hot rolled carbon manganese ferrite-bainite sheet steel." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69713.
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By means of torsion testing, the microstructures and mechanical properties produced in a 0.14%C-1.18%Mn steel were investigated over a wide range of hot rolling conditions, cooling rates and coiling temperatures. The reheating temperature was varied between 800$ sp circ$C and 1050$ sp circ$C, and strains between 0 and 0.8 were applied. This led to austenite grain sizes ranging from 10 to 150$ mu$m. Two cooling rates, 55$ sp circ$C/s and 90$ sp circ$C/s, were applied and cooling was interrupted at coiling temperatures ranging from 550$ sp circ$C to 300$ sp circ$C.Optical microscopy and TEM were used to study the microstructures. The mechanical properties were studied by means of tensile testing. A method developed by IRSID for deducing the transformation kinetics from the cooling data was adapted to the present context and used successfully to interpret the observed influence of the process parameters. (Abstract shortened by UMI.)
15
Davies, A. C. "Computer modelling of the microstructural evolution during the cooling phase of hot rolled strip steel." Thesis, Swansea University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636374.
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The modelling of the run out table in the production of hot strip steel requires the investigation into the effect of transformation kinetics of the particular steel under consideration. This requires quantifying the effects of temperature, austenite grain size and the extent of recrystallisation of the austenite before exiting the final finishing stand. In conjunction with the transformation effects on the run out table it is important that to the temperature profile of the strip in known. Therefore, because of the influence of temperature of the strip on the transformation kinetics of the material it is imperative that any model developed to predict the transformation behaviour should include a coupled thermal - microstructural analysis. The coupled two dimensional run out table model developed in the project, will allow investigations into the temperature and microstructural analysis of the cooling phase of hot strip rolling using parameters taken from the mill. The analysis of the thermal characteristics on the run out table is based on the two dimensional finite difference formulation using the energy balance procedure. This work is based upon data available from an existing one dimensional model developed by British Steel Strip Products. The investigation into the transformation characteristics of the steel under consideration (Carbon Manganese Grade) was carried out using isothermal testing conditions in the non-deformed and deformed condition. Run out table parameters such as Strip temperature, velocity and strip speed and detailed run out table temperature plots have been obtained for various cooling conditions based upon the simplified heat transfer coefficient. The temperature predictions of the strip can be seen to be as expected during the cooling in hot strip rolling. To enable further investigations into the effects of rolling parameters such as deformation schedule, extent of recrystallisation prior to cooling and the effect of varying temperature profile and structure across the strip the model has been written to be coupled into a comprehensive hot rolling model which is also being developed.
16
Goode, B. J. "The use of ultrasound to enhance the pickling of hot rolled low carbon steel strip." Thesis, Swansea University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637075.
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This study examines four aspects of the use of ultrasonics in steel strip pickling: the cavitation process, the kinetics of scale removal, the relative significance of variables in ultrasonic pickling and the application of ultrasound in a pilot-scale operation. To ensure optimum location of transducers in relation to their cavitational effects, studies were carried out in water tanks using two techniques to map cavitational activity: resistance thermometry and quantified mechanical damage to coupons of lead or aluminium. Both techniques gave similar results. Thermometric mapping had the advantage of speed but the use of a panel of lead coupons provided more tangible evidence of the mechanical influence of ultrasound in water. A cylindrical bar transducer was the most effective of those tested and could readily be adapted for use in wide strip pickling. The kinetics of pickling were analysed using a Johnson-Mehl type equation. Time exponents 'n' were in the range 2.03 - 2.56 with activation energies in the range 42.18 - 50.54 kJ/mol. The process both in normal and ultrasonic pickling was envisaged to occur by progressive undercutting and fracture of the scale. The application of ultrasonics reduced completion times considerably. To explore the individual and linked influences of variables on the pickling process, and the effect of applying ultrasonics, a statistical factorial analysis was carried out. Acid temperature was found to be the most important single variable while the most significant interaction was that between acid temperature and acid concentration. An equation has been derived reflecting the influence of all the pickling variables and their interactions. Finally, to assess better the applicability of ultrasonics to full-scale commercial operations, tests were carried out on a large pilot plant funded as part of a European Coal and Steel Community project between British Steel plc and Hoogovens Staal. The results of the smaller tests were confirmed and, furthermore, the influence of ultrasound on inhibitor efficiency was found to be insignificant.
17
Dumpawar, Shivani Kishor. "Calcium Silicate/ Phosphate Inhibitors for Corrosion Control of Hot Dipped Galvanized and Cold Rolled Steel." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439308604.
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Jondhale, Kailas Valu. "Heat transfer during multiple jet impingement on the top surface of hot rolled steel strip." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31402.
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The cooling which occurs on the runout table (ROT) is a key processing step for hot
rolled steel strip. It determines the final microstructure and thus mechanical properties as
well as flatness of the hot band. The use of multiple jets during ROT cooling results in
interactions between neighboring water jets which can affect the overall heat transfer rate.
The heat transfer which takes place during cooling with multiple jets is fairly complex and
the available knowledge is limited. The research work described was done to obtain an
understanding of the effect of varying nozzle-to-nozzle distance, plate speed and flow rate
of the impinging water on the heat transfer taking place on the ROT.
Experiments were performed on the pilot scale runout table available at UBC, using
instrumented test samples of steel. Each sample was instrumented with twenty
thermocouples which measured the internal thermal history. This data was then used in
conjunction with an Inverse Heat Conduction (IHC) model to calculate surface heat fluxes
and temperatures. Some of the variables examined included: speed of movement of the test
plate (0.22 m/s and 1 m/s), nozzle spacing (114.3, 76.2 and 38.1 mm) and water flow rate
(15 1/min and 30 1/min). These experimental results provide important information for the
development of improved runout table cooling models.
The results indicated that, during multiple jet cooling, high heat extraction takes
place directly below the nozzles and adjacent to them due to direct impact of water. Lower
heat extraction occurs at the locations between the nozzles, i.e. the interaction region.
Visual observations of the tests-indicate that, when the water jets hit the strip, a small
darkened zone can be observed at the impingement point below each nozzle. In the interaction region, the water flowing from the two adjacent jets interacts with each other
and large splashing of the water is observed in this region. The dark zones below all three
nozzles expand with cooling of the strip, indicating that the water front is progressing
outwards from the stagnation line and more water solid contact is taking place. The boiling
curves below each nozzle are similar to each other and clearly show the different boiling
regimes while the boiling curve for the interaction region does not show these regimes as
clearly. In the interaction region, heat transfer remains relatively low until the water
completely wets the strip. The investigation of the effect of strip speed indicated that the
heat fluxes are higher for lower strip speeds as the strip spends a longer time under the
nozzle. This effect was seen both below the nozzle and in the interaction region. In general,
increase in water flow rate increases heat fluxes at all measuring locations due to higher
amount of water impinged on the strip surface. The nozzle configuration having two
adjacent nozzles at 38.1 mm apart has more cooling capacity than the other two
configurations indicating that, having two nozzles close to each other enhances heat
transfer.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
19
Ritthiruth, Pawin. "Flexural Behavior of Cold-Formed and Hot-Rolled Steel Sheet Piling Subjected to Simulated Soil Pressure." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101845.
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Hot-rolled sheet piling has long-been believed to have a better flexural performance than cold-formed sheet piling based on a test conducted by Hartman Engineering twenty years ago. However, cold-formed steel can have similar strength to the hot-rolled steel This experimental program studied the flexural behavior of hot-rolled and cold-formed steel sheet pilings. This program quantified the influence of transverse stresses from soil pressures on the longitudinal flexural strength. Four cross-sections with two pairs of equivalent sectional modulus were investigated. Sheet-piling specimens were subjected to simulated soil pressure from an air bladder loaded transversely to their longitudinal axis. The span lengths were varied, while the loading area remains unchanged to examine the effect of different transverse stresses. Lateral bracings were provided at discrete locations to establish a sheet piling wall behavior and allow the development of transverse stresses. Load-pressure, load-deflection, load-strain, and moment-deflection responses were plotted to demonstrate the behavior of each specimen. The moment-deflection curves were then normalized to the corresponding yield stress from tensile coupon tests to make a meaningful comparison. The results indicate that transverse stresses influence the flexural capacity of the sheet pilings. The longer span length has less amount of transverse strains, resulting in a higher moment capacity. The hot-rolled sheet pilings have better flexural performance also because of less transverse strains.Master of Science
Sheet piling wall is an essential structure used during the excavation process. Sheet piling can be hot-rolled and cold-formed. Hot-rolled sheet piling has long-been believed to have a better bending performance based on a test conducted by Hartman Engineering twenty years ago. However, cold-formed steel can have similar strength to hot-rolled steel. This experimental program studied the bending behavior of hot-rolled and cold-formed steel sheet pilings. This program quantified the influence of lateral loading from soil pressure on the moment capacity of the sheet piling. Four cross-sections with two pairs of equivalent bending properties were investigated. Sheet-piling specimens were set up as beam members and subjected to simulated soil pressure from an air bladder. The span lengths of the specimens were varied, while the loading area remains unchanged to examine the effect of different amounts of load. Lateral bracings were provided at discrete locations to establish a sheet piling wall behavior and allow local deflection of the cross-section. Load-pressure, load-deflection, load-strain, and moment-deflection responses were plotted to demonstrate the behavior of each specimen. The moment-deflection curves were then normalized to the corresponding material property of each specimen to make a meaningful comparison between different specimens. The results indicate that lateral loading of the soil pressure influences the bending capacity of the sheet pilings. The longer span length has less amount of transverse strains, resulting in a higher bending capacity. The hot-rolled sheet pilings have better bending performance also because of less transverse strains.
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Caruso, Matteo. "Thermomechanical processing of eutectoid steels: strategies to improve the microstructure of the hot rolled strips." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209371.
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Eutectoid steel strips are designed for the production of parts for intensive use such as clutches, seat slides, and springs as they exhibitexcellent strength levels and wear resistance. These properties arise from the unique morphology of lamellar pearlite which can be considered
as a self-laminated nanoscale composite. However, a spheroidization annealing step is nowadays necessary to improve the cold forming properties before further cold rolling steps.
This thesis is aimed at improving the tensile ductility of the hot rolled products of eutectoid composition in order to eliminate the intermediate
annealing step. Two strategies are proposed.
The first is to transpose the concept of controlled rolling developed for HSLA to
eutectoid steels. Through a strict adjustment of the austenite processing and of the cooling strategy, it is possible to improve the ductility
of the final lamellar microstructure. The way the processing parameters influence the hot deformation of austenite, the eutectoid transformation and of the subsequent spheroidization annealing is deeply
investigated. It is found that refinement and pancaking of austenite
is beneficial as it reduces the pearlite block size improving the total
tensile elongation. Accelerated cooling is of paramount importance to
achieve fine Interlamellar spacing (ILS), which lead to high strength
levels and accelerate spheroidization during subsequent annealing.
The second approach involves intercritical or warm deformation. Warm processing of eutectoid steels is first explored by torsion testing
and then up-scaled to a pilot rolling-line. The interactions between thermomechanical parameters, rolling forces generated and microstructural
evolution are carefully scrutinized. During concurrent hot deformation, spheroidization of cementite takes place almost instantaneously
in both torsion and rolling. The restoration processes occurring in the ferrite matrix depends on the strain path and the strain rates. Low strain rates (0,1 s−1) and simple shear promotes the formation of a recrystallized-like HABs network of about 3μm in size.
Plane strain compression and high strain rates (10 s−1) leads to the formation of a typical recovered dislocation substructure (LABs) of 1μm in size. During annealing, no recrystallization occurs and the LABs substructure remains stable. This substructure influences drammatically the mechanical properties: the strength is very high and the work-hardening behavior is poor due to high recovery rate in the region close to the LABs. However, due to the presence of spheroidized
cementite particles the ductility of warm rolled eutectoid steels is higher than that of ultra fine grained low carbon steels.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
21
Weidenmüller, Jens [Verfasser]. "Optimization of Encircling Eddy Current Sensors for Online Monitoring of Hot Rolled Round Steel Bars / Jens Weidenmüller." Aachen : Shaker, 2014. http://d-nb.info/1058316036/34.
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Ding, Yongcong. "Residual stresses in hot-rolled solid round steel bars and their effect on the compressive resistance of members." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0030/MQ62207.pdf.
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Alzghoul, Ahmad, and Burim Hyseni. "Övergång till högre stålhållfastheter - konsekvensanalys." Thesis, Högskolan i Halmstad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-35844.
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Olah, Neto André. "Estudo do efeito da deformação plástica sobre a cinética de transformação de fase de um aço 22MnB5 estampado a quente." Universidade do Estado de Santa Catarina, 2015. http://tede.udesc.br/handle/handle/618.
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In recent decades the automobile industry has made a great effort to deal with ecological and security challenges. To do so, it was necessary to develop vehicles which are lighter, more economical and have a greater intrusion resistance when subjected to a crash. This was made possible, among other actions, by the development of advanced high strength steels, associated with the use of new manufacturing processes. Inside this approach the use of the hot stamping and the emergence of 22MnB5 boron-alloyed steel, with high hardenability, stand up. The hot stamping operation has gained great importance for enabling the manufacture of strategic components of high complexity and high mechanical resistance, associated with reasonable toughness. In order to ensure its technological evolution this process has been widely studied by numerous authors, so that the phenomenon was better understood, allowing better control as well as the quality and reliability requirements involved in the stamped components. This focus led to the development of this work, whose main objective was to study the hot stamping process, evaluating the mechanical and thermal effects. To achieve this aim an experimental apparatus was developed which allowed simulating the main thermomechanical aspects involved, such as the temperature, the conformation and the cooling. The purpose was to reproduce the conditions of the process and evaluate the influence of certain variables of the cooling speed on microstructure and on the final properties of the material, in order to study and understand some phenomena involved. This apparatus was composed of a heating furnace, an aluminum cooler, water cooled, operated at low pressure of closing and a control system, assembled on a mechanical testing 12 machine to promote the desired deformation. The experimental work was carried out in three stages. Initially, the hot plastic behavior of 22MnB5 steel was studied, evaluating the effect of temperature and strain rate on the mechanical characteristics, to determine the conditions for necking formation. In the second stage, the kinetics of phase transformation was studied, seeking to understand the effect of heating and cooling conditions on the cooling rate and on the final properties after quenching. In the last step, the plastic behavior on the kinetics of phase transformation, i.e., the effect of necking on cooling, was studied. The main objective was to show that the necking, depending on its intensity and geometry, generates the formation of a clearance between the cooler and the surface material, reducing the cooling rate to the point of affecting the mechanical properties in this region. Despite being localized, it can jeopardize the stamped component performance forming a fragile region of low mechanical strength and low toughness. It was concluded that hot plastic deformation undergone during the hot-stamping has a significant influence on the phase transformation, being necessary the proper control of process conditions so that the necking is also controlled, thus ensuring the structural homogeneity of the component and its performance.
Nas últimas décadas a indústria automobilística tem realizado um grande esforço em atender os desafios ecológicos e de segurança e para isto foi necessário desenvolver veículos mais leves, econômicos e com maior resistência à intrusão quando submetidos a um acidente. Isto foi alcançado, entre outras ações, através do desenvolvimento de aços avançados de elevada resistência mecânica, associado à utilização de novos processos de fabricação. Dentro deste enfoque se destaca dois aspectos, a utilização do processo de estampagem a quente e o surgimento do aço 22MnB5 de elevada temperabilidade ligado ao boro. A operação de estampagem a quente tem ganhado uma forte importância por possibilitar a fabricação de componentes estratégicos de elevada complexidade e elevada resistência mecânica, associada à razoável resistência ao impacto. No sentido de garantir sua evolução tecnológica este processo tem sido amplamente estudado por inúmeros autores, para que os fenômenos envolvidos pudessem ser mais bem entendidos, permitindo um melhor controle bem como o atendimento dos requisitos de qualidade e a confiabilidade envolvida nos componentes estampados. Com este enfoque desenvolveu-se este trabalho, cujo principal objetivo foi estudar o processo de estampagem a quente, avaliando os efeitos mecânicos e térmicos. Para este fim foi desenvolvido um aparato experimental, que permitiu simular os principais aspectos termomecânicas envolvidos, como a temperatura, a conformação e o resfriamento. O propósito foi o de reproduzir as condições do processo e avaliar a influência de determinadas variáveis sobre a velocidade de resfriamento, sobre a microestrutura e sobre as propriedades finais do material, no sentido de estudar e entender 10 alguns fenômenos envolvidos. Este aparato foi dotado de um forno de aquecimento, de um resfriador de alumínio refrigerado a água, operado a baixa pressão de fechamento e de um sistema de controle, montados sobre uma máquina de ensaios mecânicos para promover a deformação desejada. O trabalho experimental foi realizado em três etapas. Inicialmente foi estudado o comportamento plástico a quente do aço 22MnB5, avaliando-se o efeito da temperatura e da velocidade de deformação sobre as características mecânicas, determinando-se as condições para formação da estricção. Na segunda etapa foi estudada a cinética de transformação de fase, procurando-se entender o efeito das condições de aquecimento e do resfriamento sobre a velocidade de resfriamento e sobre as propriedades finais deste aço após têmpera. Na última etapa se relacionou o comportamento plástico sobre a cinética de transformação de fase, ou seja, o efeito da estricção sobre o resfriamento. O objetivo principal foi mostrar que a estricção, dependendo de sua intensidade e geometria, gera a formação de uma folga localizada entre a superfície do resfriador e do material, reduzindo a velocidade de resfriamento a ponto de afetar as propriedades mecânicas nesta região. Apesar de localizada esta folga pode comprometer o desempenho do componente estampado formando uma região de pouca resistência mecânica. Concluiu-se que a deformação plástica a quente sofrida durante a estampagem a quente apresenta uma significativa influência sobre a transformação de fase, sendo necessário o controle adequado das condições do processo para que a estricção também seja controlada, garantindo assim a homogeneidade estrutural do componente e o seu desempenho.
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Bau-MingSu and 蘇保鳴. "Modeling Phase Transformation in Hot Rolled Low Carbon Steel." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/88203810772786159899.
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Sue, Yu-Cheng, and 蘇育誠. "Slurry Erosion Characteristics of Hot Rolled SUS 403 Stainless Steel." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/15773656006220617059.
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碩士中華技術學院
機電光工程研究所碩士班
97
The slurry erosion characteristics of hot-rolled SUS 403 stainless steel was studied in a function of reduction ratios and temperatures. The experimental material was hot rolled with reduction ratios of 15, 30 and 50%. Then, the sample of 50% reduction ratio was tempered at 200-500℃ to investigate the influence of tempering temperatures on the erosion. Both 15% and 30% reduction ratio samples were tempered at 500℃ to compare the effect of rolling reduction ratio on the erosion with those of 50% reduction ratio sample. In this study, the erosion mode, rolling reduction, tempering temperature, grain size and mechanical properties repeat to erosion rate at different impact angle were discussed partially. The results show that a fine grained structure was obtained after hot rolling and the grain size decreased with increasing in reduction. The dominated mechanism for material removal at oblique impact angle (15° and 30°) is cutting. At higher impact angle (90°), the mechanism is based on extrusion crater. However, at medium impact angle (45° and 60°), the wear is dominated by transition of mechanism mixed with cutting and crater. For all reduction ration samples, when the samples were tempered at 500℃, the maximum erosion rate occurred at impact angle of 30°, while the minimum erosion rate occurred at normal impact angle. When the 50% reduction samples were tempered at 200-500℃, apart the 200℃ tempering sample, the maximum erosion rate occurred at impact angle of 45°, the others were at impact angle of 30°. Generally, the maximum erosion rate decreased with increasing in reduction ratios. Because the tensile strength, hardness, ductility and toughness were increased with decreasing in grain size, and then the erosion resistance was improved. The XRD analysis also show that the strain-induced transformed ε-martensite increased with increasing in impact angle.
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Bell, Grant. "THE RELATIONSHIP BETWEEN MICROSTRUCTURE AND DAMAGE EVOLUTION IN HOT-ROLLED COMPLEX-PHASE STEEL SHEET." Thesis, 2013. http://hdl.handle.net/1974/8530.
Full textAbstract:
Complex-phase (CP) steels are employed in applications that require high-strength and good edge formability. These steels derive their strength from a fine-grained bainite-ferrite microstructure, and alloying to provide solid-solution and precipitation strengthening. CP steels are produced industrially through a process of controlled rolling and cooling to produce desirable microstructures.
Hole-expansion tests are typically used as a measure of edge formability for applications such as stretch-flanges. It has been shown that CP microstructures are susceptible to large fluctuations in hole-expansion performance with little change in processing or resulting tensile properties. The steel’s characteristics of damage evolution are critical to the hole-expansion performance.
This study investigates the role of microstructure in the development of damage in CP microstructural variants. Two variant pairs of different thicknesses were produced from the leading and trailing edge of industrially produced hot-rolled sheet. Each pair consisted of a variant with poor hole-expansion performance, and a variant with good hole-expansion performance. Each variant was tested via interrupted double-notched uniaxial tension testing to induce damage. Damage evolution in each variant was quantified by X-ray micro-computed tomography (XµCT), and supplementary optical micrography. The damage results were correlated with microstructural characteristics.
It was shown that poor hole-expansion variants failed by intergranular fracture. In these variants, void damage induced by hard martensite and retained austenite was not critical in producing failure. Purely void-damaged microstructures failed by ductile fracture, whereas cracked microstructures failed in a mixed brittle-ductile failure initiated by planar cracks. Microstructural banding of large elongated ferrite grains correlated with the existence of intergranular planar fractures.Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-12-17 15:03:02.206
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Barnard, Hein. "The elastic and inelastic lateral torsional buckling strength of hot rolled type 3CR12 steel beams." Thesis, 2012. http://hdl.handle.net/10210/6885.
Full textAbstract:
M.Ing.Type 3CR12 steel is a corrosion resisting steel which is intended to be an alternative structural steel to replace the use of coated mild steel and low alloy steels in mild corrosive environments. This necessitate the experimental verification of the structural behaviour thereof. The purpose of this dissertation is therefore to compare the experimental structural bending behaviour regarding elastic and inelastic lateral torsional buckling of doubly symmetric I-beams and monosymmetric channel sections with the existing theories for carbon steel beams and to modify or develop new applicable theories if necessary. From the theoretical and experimental results it is concluded that the behaviour of heat treated Type 3CR12 beams can be estimated fairly accurate with existing theories and that the tangent modulus approach should be used for more accurate estimates as well as for beams that are not heat treated.
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Lee, Wen-Ruey, and 李文瑞. "TO IMPROVE HIGH SPEED STEEL(DIN 1.3343) HOT-ROLLED FLAT BAR YIELD BY SIX-SIGMA METHOD." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/82405728347680578662.
Full textAbstract:
碩士國立中正大學
企業管理所
96
After WTO entrance in future, the pace of import market opening will be faster. The competition for local industries to fight against exported steel goods will be definitely more violent. Some weak industries will be damaged or flunked certainly. In view of local market demands, because flat bar for building construction is affected by economic recession, the decline trend is shown. Under the blighting competition of low-cost flat bar available for mechanical structures exported from Mainland China, it has been improper for local makers to make products of general specifications. It is supposed to develop toward products featured with high additive values. Thus, the direct influence on markets posed by China products with low cost and fewer additive values can be avoided. Under the economic climate with incessantly soaring prices and increasingly violent competition of raw materials, it is required to evaluate the way how to make good use of Six Sigma kits to provide hot-rolled high speed steel flat bars with high quality, precision and additive values from the quality improvement rates of hot-rolled production techniques. As such, downstream makers can be favored with reduced cost, together with speedy, flexible and alert competition of industries. In addition, the product type gaps of local special steel markets can be well fulfilled to replace the import-depending industries in the past. This article is operated with case studies. Customers of high speed steel flat bars customarily procure black bars. Customers requested products with pre-arranged minimum dimensions for further processing to minimize the cost of raw material. In view of suppliers, makers can take the opportunity to replace the export-depending material ecotype only when black bars with stable quality and improved yield rates are provided. Thus, this study is aimed to explore the way to use Six Sigma in improving yield rates of high speed steel flat bars. This study is attempted to propose available solutions for reference through the process with issues and improvement experienced by subjects under our case studies. In this study, by using Six Sigma, it is aimed to discover the critical factors (Vital-X) affecting yield rates. By using the Finite Element Method, the hot-rolled simulation model can be created. The trial and error efforts can be saved remarkably. In combination with theories and practical discovery of optimal control methods, following problems can be solved. The said problems are: 1. critical factors affecting quality and yield rates, 2. verification of improved achievements under the control of critical factors, and 3. creation for the engineering design of hot-rolled simulation. It is expected that the win-win competence advantages of both companies under our case studies and relevant applicable industries can be reached. Finally, this article is proposed with the opinion that the critical factors to affect quality and yield rates are exactly the control over the selecting of hot-rolled billets and rolled volumes. Meanwhile, the engineering design with simulation dimensions is also created. It is allowable for on-site operators to adjust dimensions of hot roller grooves according to simulation dimensions. The trial and error efforts for practical hot rolling can be reduced with more excellent quality reachable. Keywords：High Speed Steel Flat Bar; Six Sigma; the Finite Element Method
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CHANG, LI-HSIEN, and 張禮賢. "A Case Study of the Water Mist Fire Extinguishing Systems For a Hot Rolled Steel Plant." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/2kk74c.
Full textAbstract:
碩士吳鳳科技大學
消防研究所
104
Water mist fire extinguishing systems in engineering practice examples have less available for analysis, the paper work for a hot-rolled steel plant of the hydraulic oil chamber of the water mist fire extinguishing system design, construction, testing and agreement; Through Entity brazier fire testing and FDS computer simulation results show that water mist systems for the oil fire machine chamber can achieve cooling effect of fire. this paper as a case study of water mist design and construction on the key points to provide a reference in the future.
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Huang, Rong-Shie, and 黃榮喜. "Effect of Si Content on the Scale Formation and Pickling Performance of Hot-Rolled Steel Strip." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/81815572692522844555.
Full textAbstract:
碩士國立成功大學
材料科學及工程學系碩博士班
93
Exposing to oxidizing environment, scaling always occurs on the steel surface during heating, hot-rolling and subsequent cooling. The removal of scale by pickling is a common practice before cold rolling. The thickness, chemical composition and microstructure of scale are important factors affecting the pickling efficiency. In this study, the pickling behavior of various hot rolled steels in 5 wt % HCl solution with or without Fe+2 was investigated. Four different steels with various Si content, in the range of 0.01~1.91wt %, was used. The effect of silicon content on the scale characteristics and the subsequent pickling performance was studied. XRD, SEM and EPMA were employed to analyze the microstructure and chemical composition of the scales formed in these steels. The pickling behavior was evaluated by conducting the test either in static or flowing acidic solution. The experimental results indicated that the upper and lower surfaces of the steel strips had different roughness. The results of XRD analyses showed the scale consisted of Fe 2 O 3 and Fe 3 O 4 . SEM examination exhibited that the thickness continuity and uniformity of the cross section of the scale varied considerably. It was also found that a continuous thin film or discrete particles containing Fe, Al, O and Si were present in the Fe / scale interface which might be Fe 2 SiO 4 , Fe 2 Al 2 O 4 or other silicates. The open circuit potential (OCP) measurements demonstrated that the exposure of the low silicon content carbon steel in the pickling solution might result in the formation of a meta-stable oxide on the steel surface. The formation of such meta-stable compound was characterized by the existence of a peak potential during OCP measurement. For the hot rolled steels, the experimental results showed the pickling efficiency decreased with increasing Si content in the steel. Furthermore, the presence of Fe+2 in HCl solution had no significant effect on the pickling performance of the steels in this study.
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Chiu, Jing-xin, and 邱敬欣. "Effects of hot-rolled band annealing temperature on the texture and mechanical propeties of 2205 duplex stainless steel." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/11598918960157372662.
Full textAbstract:
碩士國立雲林科技大學
機械工程系碩士班
94
This study investigates the effects of hot-rolled band annealing temperature on the texture and mechanical properties of hot rolled and cold rolled 2205 duplex stainless steel. There are two parts in this thesis. In the first part, we studied the effects of hot band annealing temperature and hot rolled reduction on the microstructure characteristics and texture of hot bands. In the second part, we studied the effects of hot band annealing temperature on the microstructure, texture, mechanical properties and formability of cold rolled steel sheets. In the first part, during hot band annealing between 950-1100℃, the grain size of transformed γ phase increased with increasing hot band annealing temperature due to less nucleation site and fast growth rate. In addition, proportion of γ phase decreased with increasing temperature and decreasing of hot rolled reduction. Furthermore, annealing temperature and hot rolled reduction didn’t change the type of texture. However, they influenced the texture intensity. Main textures of α phase are {011}<100> and {001}<110>. But, the main textures of γ phase are {011}<211> and {011}<322> for the as hot-rolled band. After hot band annealing, it changed to {011}<322>. In the second part, chromium nitride formed on the surface during the cold-rolled steel sheet annealing in the nitrogen atmosphere. In the cold-rolled state, the main texture of α phase is {001}<110> and the main texture of γ phase is {011}<211>. After cold-rolled annealing, the texture of α phase doesn’t charge. But the textures of γ phase are {011}<211> and {011}<322>. Furthermore, the elongation increased with increasing hot band annealing temperature. However, the tensile strength and yield strength decreased with increasing hot band annealing temperature. These results are influenced by their hot band microstructures. The r value and n value are lower than usual stainless steel. In addition, the planar anisotropy of the steel sheet is high. It is postulated that poor mechanical properties is due to the precipitation of σ phase for the furnace cooling after final annealing.
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Lin, Yi-wen, and 林意雯. "Effect of annealing temperature and time on microstructure and tensile properties of a hot-rolled medium Mn steel." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/96738118166984454531.
Full textAbstract:
碩士國立中山大學
材料與光電科學學系研究所
104
This study explores the effect of annealing temperature and time on microstructure and tensile properties of a hot-rolled medium Mn steel after two-stage annealing procedures. The results show that on the first annealing stage, annealing time gives similar microstructures and tensile properties, and on the second annealing stage, annealing time changes the grain size which altered austenite stability, therefore changes the tensile properties. Different annealing temperatures on the second stage change the volume fraction and Mn composition of austenite which in turn influence austenite stability, so that change the tensile properties.
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Huang, Bo-Ming, and 黃柏銘. "Effect of Mo addition on the development of microstructure in Nb Containing Low Carbon Bainitic Hot Rolled Steel Strips." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/34194340895258958554.
Full textAbstract:
博士國立臺灣大學
材料科學與工程學研究所
102
In related research, Mo element was shown to effectively enhance precipitation strengthening via nanometer-sized carbides and retard the recovery of dislocations in Nb-containing low-carbon bainitic fire-resistant steel. It is of some interest to apply the concept to another steel product, hot-rolled strips. In addition, the present study investigated the effects of adding Mo on interphase precipitation in ferritic hot-rolled strips to promote precipitation strengthening. After the comparison of the effects of Mo on the two types of hot-rolled strips, it was possible to determine whether the addition of Mo is beneficial to bainitic hot-rolled strips. The composition was primarily designed to be 0.05C-1.7Mn-0.08Nb (wt% based composition) with 0 and 0.1 wt% Mo, separately labeled Nb and Nb-Mo strips. In the practical hot-rolling process, the residual strain in prior austenite grains inevitably promotes greater transformation of ferrite, so in the present study, it was necessary to reduce the coiling temperature and accelerate the cooling rate so as to prevent the formation of a fully ferrite structure in present study. The coiling temperatures (C.T.) in the hot rolling process in this study were 450oC and 550oC. Observations of the microstructure revealed that C.T. 450oC and Mo both efficiently suppressed the ferrite transformation and promoted the granular bainite structure in bainitic hot-rolled strips. Then during the simulated coiling procedure, tempering treatment at 600oC, the strips with granular bainite demonstrated a significant secondary hardening effect. Elevating the coiling temperature to 650oC produced a fully ferrite structure with interphase precipitation in the hot-rolled strips. The strips achieved the same strength as the strips with the secondary hardening effect. However, the addition of 0.1 wt% Mo did not improve the precipitation strengthening by interphase precipitation and induced more unstable second phases in the coiling procedure in Nb-Mo strips with C.T. 650o C. From the above, it is concluded that Mo alloy has a positive effect on Nb-containing low-carbon bainitic strips. In order to increase the volume fraction of bainite and enhance the secondary hardening effect, the concentration of Mo in Nb-Mo strip with C.T. 450oC was increased to 0.3wt%, labeled the Nb-3Mo strip. In the microstructure, the morphology of bainite was the same as that of granular bainite, and the amount seems to increase with the greater addition of Mo. In further analysis to quantitate granular bainite, the electron backscattering diffraction technique was used to feature the unique misorientation gradient in granular bainite because scanning electron microscopy was unable to distinguish ferrite from granular bainite due to their similar morphologies. In the phase qualification of three hot-rolled strips with C.T. 450oC, it was surprising to find that only the high addition of Mo, 0.3wt%, effectively increased the volume fraction of granular bainite. Further dilatometry experiments led to the conclusion that the formation of ferrite must have been prohibited, allowing more prior austenite regions and the grain boundaries in the promotion of granular bainite. During tempering treatment, the high addition of Mo rarely promoted the secondary hardening effect of tempered granular bainite in Nb-3Mo strip. To determine the reason, Electron Energy Loss Spectroscopy (EELS), high resolution TEM (HR TEM), Energy dispersive X-ray spectroscopy (EDX), and atom probe tomography (APT) were used to investigate the effect of Mo solute on nanometer carbides and the dislocation structures in tempered bainite. Measurements of dislocation density revealed that no obvious recovery occurred in the three strips. It is probable that, unlike in the high temperature tensile test, the slipping of dislocation lines was slight in the current tempering treatment lacking external stress. Thus, the Mo solute could not retard the movement of static dislocation lines in granular bainite during tempering. In the evolution of nanometer carbides in tempered bainite with increasing Mo, Mo solute was homogeneously dissolved in (Nb,Mo) carbides in tempered bainite. Furthermore, the Mo solute became a significant carbide-forming element, and the carbides were slightly coarsened by absorption of excess Mo solute. In the reports on fire-resistant steel, the carbon replica method allowed confusion of the nanometer carbides in tempered bainite with strain-induced Nb carbides in prior austenite. This confusion is likely to have caused misunderstanding of the refinement of nanometer carbides by the addition of Mo in tempered bainite . In the present study, HR TEM images were used to focus on the nanometer carbides and statistically analyze their sizes during tempering because the featured Baker-Nutting orientation relationship between carbides and matrix could be recognized accurately with the technique. In addition, the signal of Mo occurred in strain-induced Nb carbides after tempering. It was concluded that Nb and Mo solute segregated toward the strain-induced Nb carbides and then formed a layer of carbides on the surface. It is likely that in previous research, segregation of Mo solute was believed to occur in the nanometer carbides in tempered bainite because the two types of carbides could not be resolved. Therefore, in the present study, it was necessary to dispel the fallacy that the addition of Mo can promote precipitation strengthening via nanometer carbides in tempered bainite in steels. Mo alloy strengthens the Nb-containing low-carbon bainitic hot-rolled strips by increasing the hardenability, rather than by a synergistic effect of Nb and Mo.
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Chiu, Hsin-Chin, and 邱信欽. "Integrated Life Cycle Assessment and Energy Management into Firm''''s Production Strategic Planning－Case Study of Integrated Steel Firm''''s Hot-Rolled Products." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/44609332268258599602.
Full textAbstract:
碩士國立中興大學
資源管理研究所
87
Green-revolution has become the acknowledged opinion recently, so that the reduction of global warming gases and development in greening products have posed an urgent call for both private and public sectors in Taiwan to adopt immediate actions to response. Energy audit can help us to monitor production procedures and collect energy consumption data in the system. It can reflect, to certain degree, detailed energy flows for each production procedure and equipment. The effectiveness of energy audit system has been examined as well as the appropriateness of top-down implementation structure has been discussed in this study. It is hope that the conceptual structure delineated in this study can be of help to formulate bottom-up policy structure for firms in industrial sector to perform a self-governed energy audit as well as environmental management systems. More reliable energy flow data from energy demand side are expected to obtain so that government can be of better control of the potential estimation of the energy conservation in related industrial sectors. This study also constructs an analytical model, which takes account of energy use, environment impact and manufacturer’s economic output performance (3E). It is the intention of this model to demonstrate the application of 3E aspects as part of the consideration of production strategic planning. Under the implementation of model, an integrated steel firm''''s hot-rolled products is chosen as case study, product yields of this firm in 2000 are estimated accordingly by the model. Simulations are also proceeded under the assumption of specific technical and resources constraints.
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Lee, Tsai-Chun, and 李采錞. "Influences of Cold Rolling Reductions and Strain Mode Changes on the through-thickness Texture Evolutions of a Hot-Rolled Non-oriented Electrical Steel." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/v3jsd2.
Full textAbstract:
碩士國立中山大學
材料與光電科學學系研究所
106
In this study, non-oriented electrical steel (NOES) which was hot-rolled and APL (annealing and pickling line) treated was used as the starting material. Two types of hot band annealed specimens were prepared and they were either ground on one side of the normal plane to remove half of the original thickness (Type Ⅰ) or on both sides of the normal plane to remove quarters of the original thickness (Type Ⅱ). These two materials were then cold rolled to different rolling reductions (50% and 78%). Depending on the different locations of the specimens, different deformation modes dominate. Therefore, five different types of specimens were obtained (S-S, SS-S, C-S, SS-C, C-C), where S stands for the surface layer of the specimen, SS stands for the sub-surface layer of the specimen, and C stands for the center layer of the specimen. The specimens were then heat treated at different annealing temperatures to obtain the early, middle and late stages of RX process, according to the measured micro-hardness value variations as a function of annealing temperature. Macrotextures were obtained by using X-ray diffractometer (XRD) to measure the pole figures. The results of the macrotexture show that α-fiber and γ-fiber intensities are observed in the CR state in the five specimens. It is also observed that α-fiber intensity increases with rolling reduction. The specimen underwent plane strain deformation is found to have the highest {111} <110> intensity. The effect of deformation mode changes is observed to be affected by rolling reductions. After the specimens were annealed at different temperatures, it is observed that the one deformed by shear deformation results in the highest intensity of Goss texture in the 78% CR specimen. Electron backscatter diffraction (EBSD) was used to observe the microstructures and microtextures. It is observed that different microstructures exist at the hot band annealed specimens and therefore Type Ⅰ and Type Ⅱ CR microstructures are compared carefully. There are more shear bands in Type Ⅰ specimen, while smooth grains with laminar morphology dominates in Type Ⅱ specimen for the 50% CR condition. Moreover, the deformed grains in C-S specimen are more elongated than those in S-S specimen. On the contrary, the microstructure difference is not obvious in the 78% CR specimens. By observing the results of the microtexture in different cold rolling reduction specimens, there are higher fractions of Goss texture in Type Ⅰ specimens, while Type Ⅱ specimens have a higher fractions of Rotated cube, {112} <110>, and Cube textures. After annealing treatments, it is observed that the 78% CR specimens are more favorable to the development of Goss texture.
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HUNG, CHEN CHING, and 陳慶鴻. "The Study of Formation Mechanism and Improvement in Surface Defects of Wire Coil- A Case Study of the Hot-Rolled Plant of X Steel Co., LTD." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/yr278g.
Full textAbstract:
碩士致遠管理學院
金屬材料工程與管理產業研發碩士專班
98
Of the wire coil surface quality defects in the rod mill plant, the highest failure rate of the rod mill materials has become the serious problem that want to solve. This study is to investigate the coil surface defects of X steel wire rod rolling processes, and statistical analysis, experimental observation and analysis, planning and implementation of the improvement and benefit evaluation methods are discussed. This study, combining with X steel ERP system data analysis, finds that in 2007, the lap and seam failure goods weight up to 941.4 tons. It accounts 44.22% of total defects, and 0.385% of the annual production. With actual observation and analysis, it is concluded the leading factors of causing rolling seam and lap surface defects includes the roller exception, adjustment, equipment, guide and other issues. Furthermore, after analyzing the cause-effect figures, the material size control, billet heating, guides, rollers, billet factors can be controlled. With the seam and lap surface defect formation mechanism analysis, it is found that the key factor is whether the formation of steel materials in rolling process can form a concave edge of the flange or poor conditions or defects. As for effects on flange in IM, roll groove fill rate up to more than 95% will result in the rolling steel flange phenomenon, of the materials which leads to complete formation of surface defects of final rolling wire.