Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 92-95).

Thesis (M.S.)--University of Iowa, 2006. / Supervisor: Ralph I. Stephens. Includes vita. Includes bibliographical references (leaf 95).

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / Title from title screen (viewed July 30, 2007). Includes bibliographical references. Online version of the print original.

Orientador: Jefferson de Oliveira Gomes / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T00:45:15Z (GMT). No. of bitstreams: 1 Buchli_Marcelo_M.pdf: 3752727 bytes, checksum: 40d7b010cd2e281baaa3faf8554cb691 (MD5) Previous issue date: 2010 / Resumo: Neste trabalho foi estudado o ferro fundido austemperado (ADI) grau 3 para substituir o aço forjado SAE 1045 temperado e revenido na aplicação do eixo comando de válvulas para motores Diesel. Na comparação dos materiais foram verificadas as propriedades mecânicas através de ensaios de laboratório e na literatura. A resistência ao desgaste foi a principal propriedade mecânica avaliada. Com o objetivo de se eliminar a operação de acabamento em retífica, especificada para os eixos comando de válvulas em aço forjado, o acabamento na usinagem de torneamento do ADI grau 3, no estado beneficiado, também foi analisado. O ADI grau3 atendeu à solicitação de desgaste quando comparado ao aço forjado e obteve um acabamento na operação de usinagem em torno, muito próximo ao acabamento do aço forjado na operação de retífica. Os resultados deste trabalho servem como base de estudo para o desenvolvimento e a fabricação de eixo comando de válvulas em ferro fundido austemperado grau 3 para motores Diesel / Abstract: The austempered ductile iron grade 3 was investigated as a substitute to SAE 1045 forged steel quenched & tempered in Diesel engines camshaft application. The mechanical properties for both materials were compared in laboratory tests and in the literature. The main mechanical property studied was the wear resistance. The microstructure, chemical composition was analyzed and correlated to camshaft requirements. The finishing turning machining characteristic of heated treated ADI grade 3 also was tested to verify the possibility of eliminating the grinding operation to SAE 1045 forged steel. As a conclusion of this study the ADI grade 3 complied with wear requirements when compared to forged steel and reached a finishing turning machining very close to grinding operation on forged steel. The results of this study can be used as basis to new development and production of diesel engines camshaft with austempered ductile iron / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Automobilistica

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M.Tech (Metallurgy) / Abrasive wear is a major factor in the production costs of the mining industry in South Africa (as is the case in the rest of the world). These costs arise from the need to replace consumables such as digger teeth, mill liners, screens and chutes. Some materials used in these areas have been used for years with little or no change to their properties such as Hadfields manganese steel; others have been significantly modified to improve their performance, as is the case with high chromium white cast iron. Some areas in the mining industry have made a complete chanlfe of material in order to reduce wear rates; the use of 9% Cr stainless steel ( ) is an example of this. In some applications metals have been successfully replaced by ceramics for example the use of alumina in combination with cemented tungsten carbides ash conditioner blades (2) at ESKOM power stations. Significant improvements in profitability (in the form of reduced consumable costs and increased productivity) can be realised by the development of new abrasion resistant materials; hence many organisations are constantly involved in such work. The fundamental property required to resist abrasive wear is hardness, however a degree of toughness is always required depending on the application. Composite materials have the best possibility of combining these properties, for example high chrome white iron can be regarded as a composite material on a microscopic scale with very hard carbides supported by a tough martensitic matrix. This material performs extremely well in many highly erosive environments; it is also relatively cheap as the "composite microstructure" forms directlJ: from casting with a heat treatment process providing a hardened matrix 3). Another example of a composite material is cemented tungsten carbide; this is manufactured as a true composite, i.e. discrete particles of tungsten carbide are sintered with cobalt particles to form a relatively tough extremely hard material. This combines the hard brittle WC with the relatively soft tough cobalt binder acting as a matrix. This material has the best resistance to abrasive wear of all metallic materials. Ceramics have higher hardness but are significantly more brittle hence their application is limited to erosive rather than abrasive environments. Cemented tungsten carbide inserts are brazed or shrunk into steel holders and used as drill tips for rock drilling; this can be regarded as a composite product, using the strong and tough steel to hold the hard tungsten carbide inserts in place.

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No description available.

Thesis (M.S.)--Oregon State University, 2004. / Printout. Includes bibliographical references. Also available on the World Wide Web.

The relationship between some mechanical properties (tensile, creep and thermal fatigue behaviour) and microstructure has been investigated for lead sheet containing <0.06 wt % Cu (the eutectic composition), made either by a conventional milling (rolling) process, or by continuous casting (Direct Method). Milled lead sheet exhibits a recrystallised microstructure, the grain size of which decreases with increasing copper content; copper is present as particles of ≃1-5 μm long, formed from the initial needles or plates of the cast billet by spheroidisation, or by particle break-up during rolling. A comparison of materials produced by several manufacturers indicates that the copper distribution and final grain size are dependent on the thermo-mechanical history of the sheet. Direct Method (DM) sheet exhibits a cast cellular structure within grains which usually extend through the full thickness of the cast sheet; copper is present as a fine dispersion (particles ≃0.5 μm diameter) at cell boundaries. The copper distribution in both materials is stable to prolonged heating (100 hours at 200<SUP>o</SUP>C), but some grain growth occurred in the milled sheet. It was not possible to obtain a fully dispersed eutectic microstructure at the eutectic composition; primary lead dendrites (or cells) were always present. This is thought to be due to the difficulty of nucleating a copper particle at the very low copper concentrations used in this work. The tensile behaviour of specimens was investigated at various strain rates and temperatures. DM sheet exhibits an increase in UTS both with increasing copper content at each strain rate, and with increasing strain rate for each copper content; no systematic variation of strain with copper content was observed. The UTS of milled lead sheet (at ambient temperature and slow strain rates) was a maximum at 0.02 - 0.03 % copper. A steady increase in UTS with increasing copper content was obtained at higher strain rates (2.67 min<SUP>-1</SUP> and above) and low temperatures (≃200 K) and indicated that a time and temperature dependent softening process is active at ambient temperature and slower strain rates (up to 1.33 min^-1) which is thought to be grain boundary sliding, although no evidence for this has been detected in the recrystallised microstructure. Values of the work-hardening coefficient (n) and the strain-rate sensitivity (m) were determined for milled and DM sheet, and were found in all cases to be high. DM sheet exhibits good creep resistance, which increases with increasing copper content, owing to the large grains and stable grain boundaries at ≃90' to the direction of stress. Milled lead sheet was less creep resistant, exhibiting maximum creep resistance at 0.03% copper; this is thought to be due to competing processes of strengthening by copper (which pins grain boundaries to some extent) and grain boundary sliding, which increases with the corresponding decrease in grain size. Thermal fatigue tests have been conducted externally, using lead flashing lengths fixed to an outside wall, and in the laboratory using specially developed apparatus. The development of the apparatus, specimen shape and test cycle length is described. Cracking is usually multiple and intergranular; examination of the fracture surface indicates a combination of intergranular fatigue, creep processes (cavitation) and regions of ductile failure. The use of acetate replicas to trace crack growth has shown the migration of grain boundaries to directions of high stress in milled lead, and in 0.01% copper DM sheet. Grain boundary migration was not observed in the more stable DM microstructures of higher copper content.