Dissertations / Theses on the topic 'Grain coarsening'
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Yu, Wanhua. "Cellular automata modelling of austenite grain coarsening during reheating." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251524.
Full textShaw, N. J. "Structure and grain coarsening during the processing of engineering ceramics." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378400.
Full textPayton, Eric John. "Characterization and Modeling of Grain Coarsening in Powder Metallurgical Nickel-Based Superalloys." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1250265477.
Full textLee, Bongjoon. "Analysis of the Kinetics of Filler Segregation in Granular Block copolymer Microstructure." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/705.
Full textChang, Chung-Shing. "Fracture processes in simulated HAZ microstructures of stainless steel." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367606.
Full textMelquíades, Sérgio dos Reis. "O efeito do carbono no aumento do tamanho de grão e nas propriedades magnéticas de aços elétricos semiprocessados após o recozimento final." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-22072007-204504/.
Full textAnnealing applied by the motors plants that are made on the semi processed electrical steels without an exact and precisious control of the decarburization on the lamination can brings undesirable results on the grain size coarsening and as a result an increasing on the core losses with a significant depreciation on the efficiency of the electrical motors. Most of the domestic motors fabrics make use of this kind of electrical steel and they do on their process the final annealing on continuous furnaces with atmospheres based on nitrogenium with around 5 until 10% of hidrogeniun and a little fraction of water vapor enough to generate an atmosphere that reacts to the carbon from the steel, eliminating it. If this decarburization is not been made sucessfully there will be an effective loss on the motor efficiency due the incresing on the core losses. Commercial samples from different steels with several carbon contents were choosen to evaluate the influence of carbon content, strain grade, time and furnace atmosphere on the grain size coarsening and core losses. It was effetived vacumn and decarburizing annealing. Core losses and grain size measurements were made in addition to the evaluation of the microstructure to determine this influence. It was verified that on the vacumn annealing, even on differents strain reductions grades, the samples with initial carbon content bigger than 300 ppm, had a meaninfull late on the grain size increase. On the situation that do not occurred a significative increase on the grain size the core losses presented undesirable high values. On the other hand samples without strain did not presented a significative increase on the grain size even with decarburization during the annealing. It was still verified that the columnar grain formation occur on specific strain grades, on decarburizing annealing and to more than 300 ppm carbon content steels. In addition where there is a fast heating rate until the annealing temperature.
Danielsson, Olivia. "Effect of carbon activity on microstructure evolution in WC-Ni cemented carbides." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226566.
Full textKlemm, Robert. "Zyklische Plastizität von mikro- und submikrokristallinem Nickel." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2004. http://nbn-resolving.de/urn:nbn:de:swb:14-1085403884093-17423.
Full textEkström, Emanuel. "Impact of Milling and Sintering on Growth of WC Grains in Liquid Co - and an evaluation of existing growth theories." Thesis, KTH, Materials Science and Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4591.
Full textCemented carbides (WC-Co) are powder metallurgical products produced by liquid phase sintering. WC-Co is widely used for making a large variety of cutting tools, such as drills and inserts turning applications, due to its great mechanical properties, where the hardness of the WC grains is combined with the toughness of the of the Co binder. WC grain size and grain size distribution are the two most important factors to control the mechanical properties of the products.
This study examined the grain growth dependence of different milling and sintering times. The resulting grain size and grain size distribution were measured using image analysis on scanning electron microscopy images (SEM) and by using electron backscatter diffraction (EBSD). In addition, the correlation between hardness and coercivity, the most common indirect measures of grain size, and different methods of calculating average grain radius were investigated. An attempt was also made to study the contribution of defects to grain growth. This work also includes an overview of various grain growth equations and a numerical implementation of these.
Experimental results show that for shorter sintering times, powders milled for short times (15 min and 1 h) have larger average grain radii. There is a crossover after 6 to 8 h of sintering, where the powders milled for a long time (40 h and 200 h), have larger average radii. The measured hardness values correlate well with the average grain radius calculated from the grain surface area and the coercivity correlates with the established equations. EBSD measurements detected boundaries that could not be detected by image analysis, and that were not Sigma 2 boundaries. It is likely that these boundaries are either low energy boundaries or boundaries between grains that are very closely oriented. Comparing heat-treated powder with the untreated resulted in a lower average grain size after sintering for the heat-treated powder. None of the growth equations investigated in this work could fully describe the experimental grain growth.
Through increased understanding of the grain growth, the growth can be controlled and the end product can have the desired tool properties. The occurrence of abnormal grains in cutting tool applications can cause breakage, which is especially important to avoid in applications such as PCB drills. A correlation between hardness and grain size provides further means for cheap and fast indirect measures of the grain size in production.
Hårdmetall är ett pulvermetallurgiskt material som tillverkas genom smältfassintring och som kännetecknas av hårdhet, styvhet och god slitstyrka. Volframkarbidens (WC) kornstorlek och kornstorleksfördelning är två viktiga faktorer för att kontrollera de mekaniska egenskaperna i hårdmetall.
I den här studien har korntillväxtens beroende på malning och sintring undersökts. WC-Co maldes och sintrades fyra olika tider och kornstorleksfördelningen mättes med bildanalys på svepelektronmikroskopbilder samt med ``electron backscatter diffraction'' (EBSD). I arbetet har även korrelationen mellan hårdhet, koercivitet och olika sätt att beräkna medelkornstorleken undersökts. Ett försök har också genomförts för att studera hur defekterna i det malda pulvret påverkar korntillväxten. I arbetet har även ett flertal olika tillväxtekvationer modellerats numeriskt och för och nackdelar med de olika tillväxtekvationerna har vägts mot varandra.
En lång maltid (40 h och 200 h) visade sig ge liten kornstorlek för sintring kortare än 6 h, men för sintringar längre än 8 h gav istället kort malning (15 min och 1 h) den mindre kornstorleken. Det visade sig att uppmätt hårdhet korrelerar bäst med den medelkornstorleksradie som räknats fram från kornytan. I EBSD mätningarna kunde man observera ett flertal korngränser, utöver Sigma 2 korngränser, som inte hade detekterats med bildanalys. Värmebehandlingen av det malda pulvret minskade korntillväxten under efterföljande sintring. Ingen av de undersökta tillväxtekvationerna kunde beskriva de experimentella resultaten fullt ut.
Genom ökad förståelse för korntillväxt kan man kontrollera tillväxten och slutprodukten kan få önskade egenskaper. Förekomsten av abnorm korntillväxt i skärverktyg i hårdmetall är en av de vanligaste kritiska defekterna och det är speciellt viktigt är undvika korntillväxt i tillverkning av små verktyg, som till exempel kretskortsborrar. Hårdhet och koercivitet är de vanligaste indirekta mätmetoderna för att mäta kornstorlek i produktion. En bra korrelation mellan kornstorlek och indirekta mätmetoder ger utökade verktyg för snabba och billiga mätningar.
Klemm, Robert. "Zyklische Plastizität von mikro- und submikrokristallinem Nickel." Doctoral thesis, Technische Universität Dresden, 2003. https://tud.qucosa.de/id/qucosa%3A23831.
Full textArnaud, Laurent. "Modélisation de la transformation de la neige en glace à la surface des calottes polaires : étude du transport des gaz dans ces milieux poreux." Phd thesis, Université Joseph Fourier (Grenoble), 1997. http://tel.archives-ouvertes.fr/tel-00709566.
Full textChen, Chun-Chi, and 陳俊吉. "Study on Grain Coarsening in Aluminum Alloy 6061 By Using Ring Compression Test." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/14130181810493860863.
Full text國立中興大學
機械工程學系所
104
This research is trying to use ring compression method, in different time to heat preservation and different heat treatment to figure out development of grain size. The research used Aluminum 6061 as material and used Taguchi method to get process parameters of material temperature, ring compression speed, the mount of compression and lubricant in ring compression test and coarse grain process. After numbers of experimental results, the researchers found out the most influence average grain size is lubricant, next is material temperature, and next is the mount of compression, the last ring compression speed has minimal impact in the test. The researchers used finite element method program DEFORM to analysis the development of grain size in ring compression process and compared with test, the result showed: Using lower friction coefficient made aluminum 6061 deformed will-distributed, also brings dynamic recrystallization distribution ratio will-distributed, and the average of grain size smaller than others. As the material temperature raise up, aluminum 6061 all produced dynamic recrystallization, but after ring compression the researchers compared the original material found overall grain size not change too much. Although through the experiment and calculated an overall grain size was not the same as simulation, but it has same development trend, showed the simulation is feasible. The research used after ring compression material to heat preservation in different time, and found after 2 hours continued heat preservation, the material’s inside still residual strain, made produce recrystallize. And after 3 hours continued heat preservation, grain started to grow up. In terms of heat treatment, results showed T4 and T6 heat treatment can reduced the average of grain size, and given a different effectiveness period of time of treatment did not affect change in grain size.
Mei-HsuanChen and 陳美璇. "Effect of Magnesium Addition on Grain Coarsening in Low Carbon Steels during Austenitizing Process." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/14744570671681108272.
Full textMaya, Kini K. "Interfacial Processes in Densification of Cubic Zirconia." Thesis, 2016. http://hdl.handle.net/2005/3158.
Full text"An evolution concerning coarsening of the urban grains in Mong Kok District." 2003. http://library.cuhk.edu.hk/record=b5891775.
Full text"Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2002-2003, design report."
Includes bibliographical references (leaf 76).
THESIS STATEMENT & INTRODUCTION --- p.1
URBAN GRAINS --- p.2
THESIS PROPOSAL --- p.3
THE PROJECT --- p.4-9
With Outling Zoning Plans (1990 & 2000)
Main issued researched & Special objectives on this thesis --- p.10-11
SITE ANALYSIS --- p.12-43
Chapter 1 --- Content page --- p.12
Chapter 2 --- District Level --- p.13-22
Chapter 3 --- Street Level --- p.23-34
Chapter 4 --- Building Level --- p.35-41
Chapter 5 --- Site selection --- p.42-43
DESIGN PART --- p.44-46
Chapter 6 --- Design issues
Chapter 7 --- District methodology
Chapter 8 --- The program
Chapter 9 --- Design tectonics
Chapter 10 --- Site selection
DESIGN DEVELOPMENT --- p.47-50
Chapter 11 --- Stage 1 - sketches --- p.47
Chapter 12 --- Stage 2 - Sketches --- p.48
Chapter 13 --- Stage 2- A preliminary thought on site planning --- p.49
Chapter 14 --- Stage 3 - Test on service planning configuration --- p.50
DESIGN CONCEPT --- p.51-59
Chapter 15 --- Merged organism growing in future --- p.51-52
Chapter 16 --- Concept 1 - Mong Kok under 7 storeys --- p.53-54
Chapter 17 --- Concept 2 -- Software & Hardware --- p.55-57
Chapter 18 --- Concept 3 - Facade Coverage --- p.58-59
PROGRAM / FUNCTIONAL SPACES DESIGNED --- p.60-61
FIANL DRAWINGS- FLOOR PLANS --- p.62-65
BUILDING SECTIONS --- p.66
DIAGRAMS & EXPLANATORY SECTIONS --- p.67-74
The DESIGN AS SUMMARY --- p.75
REFERENCES & ACKNOWLEDEMENTS --- p.76