Dissertations / Theses on the topic 'Pearling'
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com, dbearham@hotmail, and Douglas Bearham. "Identification and characterisation of two haplosporidian parasites of oysters in north Western Australia." Murdoch University, 2008. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20081114.120135.
Full textMayo, Lisa Cheree. "Mathematical modelling of the impaction and spreading of spray droplets on leaves." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/91389/1/Lisa%20Cheree_Mayo_Thesis.pdf.
Full textTian, Falin. "Interaction between Nanoparticles and Aggregates of Amphiphile Molecules." Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1002.
Full textAmphiphile molecules, endowed with a particular structure containing a hydrophilic head and a hydrophobic tail, have many important applications, e.g., fabrication of detergents, surface coating or surface functionalization, etc. Molecular aggregates of various forms, micelles, vehicle, membranes, etc. can be formed from amphiphile molecules. The complexity of these molecular aggregates involving a large number of atoms make the theoretical study of these system very challenging. Up to now, our understanding of the interaction between nanoparticles and aggregates of amphiphiles remains quite incomplete. Using a variety of molecular simulation methods and some theoretical approaches (Helfrich theory and perturbation theory), we have studied the following issues in the present thesis: 1. How the presence of nanoparticles, especially due to their highly curved surfaces, affects the aggregation of the amphiphiles? 2. How a lipid bilayer, a particular amphiphile aggregate, induces the self-assembly of hydrophobic nanoparticles.3. How the morphology transition of a membrane nanotube can be induced by nanoparticles?
Keiser, Armelle. "Dynamiques sur des surfaces texturées et imprégnées." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS601.
Full textThis thesis aims at characterizing drops, bubbles and thin films dynamics on biomimetic textured surfaces, impregnated with oil (known as LIS in the literature). When an aqueous liquid is deposited on such surfaces, the four phases at stake (oil, air, textures and deposited liquid) generate multiple interfaces, playing a crucial role in the various dynamics observed. The viscous friction opposing the motion of a drop on an inclined LIS at low capillary numbers is studied as a function of the oil/drop viscosity ratio. The results revealed the crucial role of the microscopic oil meniscus surrounding the foot of the drop. Then, two experiments focusing on the dynamics of a receding contact lines are studied: the dewetting of a thin aqueous film and the pearling instability. In both cases, the qualitative behavior is similar to the one reported in the literature on conventional solid surfaces. However, a deeper study reveals that the presence of oil changes quantitatively the dynamics. The flow in both the aqueous and the oil phases must then be taken into account simultaneously. The results obtained in this work highlight the originality of those surfaces, and shed new light on the very peculiar role of the oil meniscus surrounding the contact lines
Pandit, Ashwin Suresh. "Theory of the pearlite transformation in steels." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609797.
Full textRiehm, Derek J. "Kinetics of the pearlite to austenite reversion transformation." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29739.
Full textApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Das, Bakshi Subhankar. "Wear of fine pearlite, nanostructured bainite and martensite." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/262770.
Full textMojtaba, Mansouri Arani. "Static strain aging in low carbon ferrite-pearlite steel : forward and reverse loading." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/55894.
Full textApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Erkami, Ali Akbar. "The studies of high strain deformation in carbon steels containing differing amounts of pearlite." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303427.
Full textJohn, Pearlie Marie. "A qualitative assessment of the insulation systems of medium voltage induction motors / Pearlie Marie John." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1358.
Full textThesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2007.
Garnham, John Ernest. "The wear of bainitic and pearlitic steels." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/9148.
Full textKinap, Paulo Eduardo Barros. "Tratamentos térmicos para obtenção de cementita esferoidizada em ferro fundido nodular." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-11072017-145654/.
Full textThe purpose of the present work, consisted in obtaining ductile casting iron, that will be used in the shaft production, with de following mechanical properties after the appropriated heat treatments: ultimate tensile strength and yield strength values of 700 N/mm2 and 450 N/mm2 minimum respectively, elongation of 5% minimum and hardness value from 235 to 285 HB. The microstructure more adequated to obtaining the desired mechanical characteristics should consist of spheroidized cementite in a ferritic matrix, to be obtained with the annealing or tempering treatments of microstructures previously pearlitic or martensitic respectively. In the case of the annealing treatment, the initial structures consisted of thick pearlite plus ferrite, wich were in the material in the ascast state, or fine pearlite plus ferrite, of the normalized material. All the used heat treatment, depending on the time of treatment, allowed the obtainment of spheroidized cementite. The material normalized and annealed for 2 hours at 700°C made possible the obtaining of the desired mechanical properties: ultimate tensile strength and yield strength value of 827 N/mm2 and 547 N/mm2 respectively, elongation of 7% and hardness values of 277 HB, values these, in acordance with the aims initially proposed in the present work. In the case of the material quenched and tempered at 700°C for 0,5 hour, it was obtained yield strength values of 542 N/mm2, elongation of 6% and hardness value of 246 HB. The annealing treatment made during 48 hours, produced a microstructure almost totally ferritic, with small areas of aggregated carbides. The remaining of the carbon migrated to the graphite nodules producing secondary graphite around them.
Gießmann, Adam Andreas [Verfasser], Ingo [Akademischer Betreuer] Steinbach, and Werner [Akademischer Betreuer] Theisen. "The influence of stress enhanced diffusion on the growth of pearlite in eutectoid plain carbon steel / Adam Andreas Gießmann. Gutachter: Ingo Steinbach ; Werner Theisen." Bochum : Ruhr-Universität Bochum, 2016. http://d-nb.info/1082425877/34.
Full textDyčka, Martin. "Optimalizace technologie perlitizace masivních vývalků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319561.
Full textLiu, Ning. "Microstructure and mechanical properties of cold drawn steel wires." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2012. https://ro.ecu.edu.au/theses/512.
Full textMoreno, Marc. "Mécanismes métallurgiques et leurs interactions au recuit d’aciers ferrito-perlitiques laminés : caractérisation et modélisation." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0068.
Full textFerrite/Martensite Dual-Phase steels are largely used in the form of thin sheets in the automotive industry for their excellent balance between resistance and strength and thus for their lightening potential. They are elaborated by continuous casting, hot- and cold- rolling, followed by a continuous annealing. During the heating and the soaking stages of this latter process, the deformed ferrite/pearlite microstructure obtained after rolling evolves is transformed into a recrystallized ferrite-austenite microstructure. The experiments show that recrystallization and austenite transformation kinetics as well as the resulting spatial and morphological distribution of the phases are highly sensitive to the heating rate. This PhD thesis aims at understanding the different metallurgical mechanisms explaining this particular sensitivity as carbides ripening, recovery, recrystallization and austenite transformation and all their possible interactions. The mechanisms were characterized at different scales and by in situ technics on an industrial steel and model by physical based approaches in order to drive future production lines. After a first chapter dedicated to the experimental and modeling methods, the second chapter deals with the characterization of the morphogenesis of ferrite-austenite microstructures by Scanning Electron Microscopy (SEM). Chapter 3 is a study by Transmission Electron Microscopy (TEM) and by thermokinetic modeling (ThermoCalc, DICTRA) of the chemical composition of carbides along with manufacturing, from hot-rolling to annealing. Recovery and recrystallization are studied in chapter 4 by the means of in situ High Energy X-Ray Diffraction (HEXRD) experiments conducted on a synchrotron beamline and modeled by an original mean-field approach. Finally, chapter 5 proposes an analysis with DICTRA to understand austenite transformation kinetics as function of heating rates. The proposed approach is innovative as it accounts for intergranular carbides in the ferrite matrix, is conducted in non-isothermal conditions and propose a fine analysis of growth modes of austenite associated to manganese, a key alloying element of the studied steels
Agudelo, Juan Ignacio Pereira. "Analysis of the microstructure transformation (wel formation) in pearlitic steel used in relevant engineering wear systems." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-04092018-131559/.
Full textNesta tese foi caracterizado o comportamento do aço perlítico em condições controladas de desgaste em laboratório e em serviço em dois estágios do processo de mineração de minério, cominução e transporte ferroviário. A tese consiste em três capítulos experimentais divididos segundo o tribosistema analisado. Em todos os capítulos do trabalho foi utilizada a técnica de microscopia eletrônica para análise microestrutural. Foi utilizado Microscopia eletrônica de varredura (MEV), Focused Ion Beam (FIB-SEM), Electron Backscatter Diffraction (EBSD) e Microscopia eletrônica de transmissão (MET). O primeiro capítulo experimental mostra a análise da perlita in condições de desgaste abrasivo com partículas soltas em eventos múltiplos. As amostras foram tiradas de um moinho semi-autógeno (SAG) e realizada uma simulação experimental do desgaste em condições controladas usando o tribômetro de roda de borracha (RWAT). Os resultados mostraram a formação de camada branca em ambas as condições de análise, consistindo em uma camada poli cristalina caracterizada pela formação de grãos ultrafinos na camada mais próxima da superfície de desgaste. Também foi concluído que a roda de borracha pode simular o desgaste produzido nos moinhos SAG tanto nas características superficiais quanto microestruturais em condições de maior severidade as comumente utilizadas na norma ASTM G65 (procedimento B). O Segundo capítulo experimental explora a caracterização da microestrutura depois da passagem do endentador no ensaio de riscamento (scratch test) utilizando duas condições de carga normal aplicada e 5 sequências de riscamento. A análise microestrutural mostrou a formação de duas camadas subsuperficiais identificadas pelo nível de alteração microestrutural. Na camada mais próxima da superfície de desgaste foi observada a formação de grãos ultrafinos de ferrita. A segunda camada identificada mais profundamente na amostra, denominada como camada de transição, é caracterizada pela combinação de colônias deformadas (redução do espaçamento interlamelar) e camadas não afetadas pelos esforços produzidos no contato. Nesta camada foi determinada a texturização em direção RD // nas amostras testadas a 4 N (carga normal aplicada) e uma passada. Posteriormente à análise de riscamento foi caracterizada a microestrutura de uma amostra tirada de um trilho esmerilhado (processo industrial que pode ser considerado como aplicação do ensaio de riscamento). Foram consideradas duas condições de esmerilhamento com variação de velocidade de esmerilhamento (deslocamento linear do veículo esmerilhador) e potência dos motores dos rebolos usada no procedimento. A combinação de baixa velocidade de esmerilhamento e alta potência nos motores controladores dos rebolos promoveu uma grande deformação nas camadas subsuperficiais na região de contato e uma baixa aleatoriedade das orientações cristalográficas das colônias de perlita. Finalmente, no capítulo três, a caracterização da microestrutura perlitica foi finalizada com o estudo de amostras de roda e trilho em condições de desgaste em campo e de Rolling Contact Fatigue (RCF) em ensaios de laboratório. A simulação experimental foi realizada utilizando o tribômetro twin-disc rolling (configuração disco-disco) com variação do número de ciclos. A caracterização da roda ferroviária mostrou a formação da camada branca caracterizada por níveis de cementita fraturada e alinhada em direção do movimento de rolamento/deslizamento com áreas de dissolução do átomo de carbono na ferrita formando uma ferrita supersaturada. Foi identificado a formação de policristais de ferrita (grãos ultrafinos) na camada mais superficial e uma orientação preferencial RD // na camada de transição. Os resultados dos ensaios de laboratório mostraram a nucleação de trincas superficiais se propagando a baixo ângulo na camada branca. A transformação microestrutural dessa camada após ensaios de laboratório consiste em policristais de ferrita e dissolução da cementita.
Chaves, Ana Paula Gonçalves. "Rodas ferroviárias: análise, microestrutura e propostas de melhoria." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-02032017-144335/.
Full textResearch about rail transport in Brazil has been intensified recently due the need to improve the wheel-rail performance, considering the demand of increasing axle load aiming for transportation cost reduction. Changes in the material microstructure or in the alloys composition can improve the wheel-rail resistance. A eutectoid steel similar to that used in conventional class C AAR wheels (designed to heavy haul transportation - high loads and low speeds) was submitted to isothermal heat treatments applying dilatometry techniques at ten different cycles. Different microstructures (totally pearlitic and pearlitic-bainitic) were obtained and their influence on the mechanical and magnetic properties was analyzed. The analysis included metallographic techniques (identification of phases and pearlite interlamellar spacing), magnetic testing (magnetic saturation and magnetic Barkhausen noise) and mechanical testing (hardness and pin-ondisc tests). Railway wheels Class C ARR were characterized in four different conditions: new and used, cast and forged.
Green, Colin S. "Case studies of effective assimilation programs in selected churches." Theological Research Exchange Network (TREN), 2008. http://www.tren.com/search.cfm?p001-1241.
Full textCaruso, 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.
Full textexcellent 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
Pan, L. (Longxiu). "Two methods for processing an ultrafine ferritic grain size in steels and the thermal stability of the structure." Doctoral thesis, University of Oulu, 2004. http://urn.fi/urn:isbn:951427489X.
Full textFager, Fredrick, and Serg Chanouian. "Nuclear Waste Canister : Evaluating the mechanical properties of cassette steel after casting." Thesis, KTH, Materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209803.
Full textThe Swedish Nuclear Fuel and Waste Management Company (SKB) have developed a final storage canister that will contain waste from the Swedish nuclear power plants. However, it is still in a development phase and therefore different types of methods and canister materials are investigated to produce the most durable and safe canister. The canister is made of a copper tube with a welded bottom and lid with an insert. The insert is a cylindrical construction of nodular cast iron that contains a welded steel cassette, to make space for the spent fuel, and a steel lid. The steel tubes showed inhomogeneous properties after being exposed to a casting around them. The aim of this investigation is to clarify the impact of casting on the chemical composition of the steel as well as the microstructure. The cause to the inhomogeneous properties were the diffusion of carbon from the cast iron to the steel, which then produced a harder and more brittle material. Experiments and simulations were used to see the carbon diffusion into the steel as well as what happens with the chemical composition in the affected zones. Identification of phase changes, diffusion and microstructures contributed to changes of mechanical properties in the steel.
Mäkinen, Katri. "Optimisation of local material parameters : Optimising local material parameters in ductile cast iron cylinder head casting." Thesis, Jönköping University, JTH, Material och tillverkning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-54500.
Full textKuprin, Corinna. "Verformungsverfestigung bei zyklisch inkrementeller Torsion von Reineisen und dem Stahl 42CrMo4N." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-103890.
Full textFerritic-pearlitic steel 42CrMo4N and pure iron under different strain paths are compared regarding their flow behaviour. Mainly in cyclic torsion tests with resulting strain increment per cycle shear stresses and strain hardening are analysed. The results show, that the cementite lamellae determine the flow behaviour of the steel 42CrMo4N, whereas the properties of pure iron are governed by the evolving dislocation cell structure. The dependency of flow stress on the strain direction is different for the two materials. Yield surfaces describe strain hardening quantitatively. The procedure for yield point detection and the dependency of subsequent yield surfaces on experimental conditions and strain states is shown. For pure iron isotropic hardening, for steel 42CrMo4N kinematic strain hardening dominates the flow behaviour
Suyitno, Budhi-Muliawan. "Etude du comportement en fatigue d'aciers à dispersoïdes." Poitiers, 1988. http://www.theses.fr/1988POIT2342.
Full textXiong, Xiao Chuan. "Élaboration et genèse des microstructures dans les "aciers" fer-azote." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL079N/document.
Full textCar designers are seeking ways to increase the proportion of parts made of sheet steels of higher strength and lower cost. The parallel between the Fe-N and Fe-C phase diagrams shows that it is possible to develop similar steels in the Fe-N system. The objective of this study was to prepare binary Fe-N steels and to develop structures equivalent to those in carbon steels. Approaches to meet the objectives are considered: Preparations of Fe-N steels: gas nitriding in austenite domain followed by homogenization treatments allowed to introduce high amount of nitrogen in pure iron sheet. A simulation of the nitrogen diffusion was proposed to describe the weight increase during nitriding. Genesis of microstructures: The slow cooling of the Fe-N austenite led to lamellar and globular pearlitic structures composed of ferrite and nitrideFe4N. An acicular microstructure, which is the consequence of the precipitation of the ferrite in the nitride Fe4N, was also identified. The slow cooling of the supersaturated Fe-N ferrite led to the precipitation of the stable nitride Fe4N and the metastable nitride Fe16N2, which witnessed a rapid diffusion of nitrogen in ferrite at low temperature, comparable to that of carbon. The multiphase microstructures [alpha+alpha'+gamma] were obtained by intercritical treatments followed by quenching. The intercritical domain was reviewed using the sub-lattice model. In-situ TEM investigations have identified the precipitation of Fe16N2 nitride in the ferrite during the aging at 85 °C. High amount of the residual austenite have been identified, which would be the basis for development of TRIP nitrogen steels
Pappas, Adlreburg Nickolas. "To Make Iron of Iron : A Comprehensive Analytical Study of Spade Shaped Iron Bars." Thesis, Stockholms universitet, Arkeologiska forskningslaboratoriet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-145694.
Full textHumiski, Lisa. "Effects of pearling level and genotype on physical grain characteristics, composition, and technological and sensory properties of selected western Canadian barley varieties." 2011. http://hdl.handle.net/1993/4500.
Full textCaines, Megan. "The experiences of two caregiver populations : an application of Pearlin's stress process framework." Thesis, 2008. http://hdl.handle.net/1828/2581.
Full textPham, Tri T. "Mathematical modelling of the onset of transformation from austenite to pearlite under non-continuous cooling conditions." Thesis, 1993. http://hdl.handle.net/2429/2384.
Full textSong, Yuan-Shung, and 宋元聖. "The study of a eutectoid reaction for the formation of κ-pearlite in a Mn-Al steel." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/dwp3xy.
Full text國立臺灣科技大學
機械工程系
99
We have studied the phase transformations of a Mn-Al steel during low temperature aging processes. The heat treatment of the steel was solution treated at 1100℃ and followed by heating isothermally at temperatures from 850 to 500℃. The composition of the steel is Fe-14.5 Mn-6.4 Al-0.78 C (wt%). The constituent phases of the Mn-Al steel is single austenite at temperatures between 1100 and 825℃. At temperatures below 800℃, ferrite and ??carbide precipitate at the grain boundaries of the austenite matrix. Furthermore, at aging temperatures below 675℃, we found lamellar grains of ferrite and ??carbide forming ??pearlite appear in the austenitic grains as pearlitic colonies. It is a eutectoid reaction which supersaturated austenite decomposed into ferrite and ??carbide. The ??pearlite nucleated at the grain boundary areas, grow into the austenitic matrix, and form pearlitic colonies in the austenitic matrix. The ??pearlite is very similar to the pearlite in steels, except that the carbide is in different crystal structure. When the aging temperatures are lower than 625℃, in addition to ferrite and ??carbide grains in ??pearlite, we found M23C6 carbide precipitates in the lamellar ferritic grains. The appearance of the M23C6 carbide is a result of the decomposition of supersaturated ferrite into more stable ferrite and M23C6 carbide. Thus, the constituent phases of the Mn-Al steel are austenite, ferrite, ??carbide and M23C6 carbide. The M23C6 carbide precipitates inside the ferritic grains of the ??pearlite. The trends for the compositions of the constituent phases are as follows. The Mn content in various phases in the decreasing trend is M23C6, ??carbide, austenite, and ferrite. The Al content decreasing trend of the phases is ??carbide, ferrite, austenite, and M23C6 carbide. We found a K-S orientation relationship exists between k-carbide and ferrite: [01 ]κ//[ 11]α, (111)κ//(110)α. The same situation exist between M23C6 and ferrite: [01 ]C//[ 11]α, (111)C//(110)α
John, Pearlie Marie. "A qualitative assessment of the insulation systems of medium voltage induction motors / by Pearlie M. John." Thesis, 2007. http://hdl.handle.net/10394/1358.
Full textLin, Chia-Chi, and 林家吉. "Effect of Pearlite Stabilization on Tensile Embrittlement and Thermal Shocking Failure of S.G. Cast Iron at Elevated Temperatures." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/04475442957392103674.
Full text國立成功大學
材料科學及工程學系碩博士班
96
This study is intended to evaluate how feasible it is to suppress the intergranular embrittlement fracture behavior of spheroidal graphite (SG) cast iron with the formation of pearlite in the cast iron. Intermediate-temperature embrittlement and cyclic heating induced embrittlement are investigated in this study. In the latter case, the primary objective is to examine the effect of cyclic heating at the maximum temperature and the resultant microstructural change due to the instability of pearlite at high temperatures. Two types of SG cast iron have been chosen. One is as-cast SG cast iron that has been added with pearlite promoting elements (Cu, Mn and Cr) and has a bull’s eye structure. The other is SG cast iron which has undergone a ferritization heat treatment to achieve a matrix with lower pearlite content and is used as a contrast material. Experimental results indicate that the location of crack nucleation remains the same despite the existence of pearlite. The hindrance of pearlite to the propagation of cracks that emerge from eutectic cell boundary regions is also unapparent. Consistence is found in the intermediate-temperature embrittlement fracture behaviors between SG cast irons with different pearlite contents, namely that in-tergranular fractures only occur in the ferritic region. The RT~550℃ tensile strength and crack cross sections of SG cast irons with different pearlite contents reveal the differences in grain strength and grain boundary strength between pearlite and ferrite. This also leads to the higher critical fracture stress of pearlite compared to ferrite and the higher equicohesive temperature(ECT) in pearlite compared to ferrite. These are verified by the result that intergranular fractures only occur in the ferritic region of SG cast iron at specific tem-peratures. On the other hands, when the cyclic heating temperature reaches 800℃, significant martensitic phase transformation occurs and results in anmarked change in the tensile property. When cyclic heating temperature reaches 750℃, the decomposition of pearlite is mainly responsible for the change in the tensile property at the room temperature. More notably, such decomposition is less significant in the SG cast with lower pearlite percentage. Finally, an intermediate temperature tensile test following cyclic heating confirms that pearlite has a higher critical fracture stress than ferrite.
Garrison, Christy C. "“Still Here”; The Enduring Legacies Of Dorothy Bolden, Ella Mae Wade Brayboy, And Pearlie Dove’s Community Leadership In Atlanta, 1964-2015." 2017. http://scholarworks.gsu.edu/history_diss/61.
Full textKuprin, Corinna. "Verformungsverfestigung bei zyklisch inkrementeller Torsion von Reineisen und dem Stahl 42CrMo4N." Doctoral thesis, 2012. https://monarch.qucosa.de/id/qucosa%3A19830.
Full textFerritic-pearlitic steel 42CrMo4N and pure iron under different strain paths are compared regarding their flow behaviour. Mainly in cyclic torsion tests with resulting strain increment per cycle shear stresses and strain hardening are analysed. The results show, that the cementite lamellae determine the flow behaviour of the steel 42CrMo4N, whereas the properties of pure iron are governed by the evolving dislocation cell structure. The dependency of flow stress on the strain direction is different for the two materials. Yield surfaces describe strain hardening quantitatively. The procedure for yield point detection and the dependency of subsequent yield surfaces on experimental conditions and strain states is shown. For pure iron isotropic hardening, for steel 42CrMo4N kinematic strain hardening dominates the flow behaviour.