The debug register rootkit is a special type of rootkit that has existed for over a decade, and is told to be undetectable by any scanning tools. It exploits the debug registers in Intel’s IA-32 processor architecture. This paper investigates the debug register rootkit to find out why it is considered a threat, and which malware removal tools have implemented detection algorithms against this threat. By implementing and running a debug register rootkit against the most popular Linux tools, new conclusions about the protection of the Linux system can be reached. Recently, debug register rootkits were found on Windows as well. This project intends to bring knowledge about the problem and investigate if there are any threats. Our study has shown that still after 12 years, the most popular tools for the Linux operating system have not implemented any detection algorithms against this threat. The security industry may need to prepare for this threat in case it is spread further.

Magnesium is the lightest metal that can be used for structural applications. For the reasons of weight saving, there has been an increasing demand for magnesium from the automotive industry. However, poor formability at room temperature, due to a limited number of slip systems available owing to its hexagonal close packed crystal structure, imposes severe limitations on the application of Mg and its alloys in the wrought form. One possibility for improving formability is to form the components superplastically. For this, it is necessary to refine the grain structure. A fine-grained material is also stronger than its coarse grain counterpart because of grain size strengthening. Moreover, fine-grained magnesium alloys have better ductility as well as a low ductile to brittle transition temperature, thus their formability at room temperature could be improved. In addition to grain refinement, the issues pertaining to poor formability or limited ductility of Mg alloys can be addressed by controlling the crystallographic texture. Recently, it has been shown that warm equal channel angular extrusion (ECAE) of magnesium led to reduction in average grain size and shear texture formation, by virtue of which subsequent room temperature rolling was possible. Based on the literature, it was also certain that, in order to make magnesium alloys amenable for processing, grain refinement needs to be carried out and the role of shear texture needs to be explored. Since processing at higher temperature would lead to relatively coarser grain size, large strain deformation at lower temperatures is desirable. The present thesis is an attempt to address these issues. The thesis has been divided in to eight chapters. The chapters 1 and 2 are dedicated to introduction and literature review on the subject that provides the foundation and motivation to the present work. Subsequent chapters deal with the research methodology, experimental and simulation results, discussion, summary and conclusion. In the present investigation, two single phase alloys were chosen, the commercially pure magnesium and the magnesium alloy AM30. These materials were subjected to suitable processing techniques, detailed posteriori. A systematic analysis of microstructure and texture for each of the as-processed materials was performed by electron backscattered diffraction (EBSD) using a field emission gun scanning electron microscope (FEG-SEM). Bulk texture measurement by X-ray diffraction, neutron diffraction and local texture measurement by synchrotron X-rays were also carried out. In addition, dislocation density was measured using X-Ray diffraction line profile analysis (XRDLPA). The experimental textures were validated by using Visco-Plastic Self Consistent (VPSC) simulation. The details of experimental as well simulation techniques used in the present investigation is described in chapter 3. To understand the philosophy of large strain deformation by shear in magnesium and its alloy, free end torsion tests could provide a guide line. Based on the understanding developed from these tests, further processing strategy could be planned. Therefore, a rigorous study of deformation behaviour under torsion was carried out. In chapter 4, the results of free end torsion tests carried out at different temperatures, 250⁰C, 200⁰C and 150⁰C and strain rates, 0.01 rad.s-1, 0.1 rad.s-1, 1 rad.s-1 are presented for both the alloys. In addition to the analysis of stress-strain behaviour, a thorough microstructural characterization including texture analyses pertaining to deformation and dynamic recrystallization was performed. Both pure Mg and the AM30 alloy exhibit similar ductility under the same deformation condition, while the strength of AM30 was more. The strain hardening rate decreased with temperature and increased with strain rate for both the materials. However, the strain hardening rate was always higher in case of the alloy AM30. Large amount of dynamic recrystallization (DRX) was observed for both the alloys. The initial texture had an influence on the deformation behaviour under torsion and the resulting final texture. The initial non-axisymmetric texture of pure Mg samples led to nonaxisymmetric deformation producing ear and faces along the axial direction, and the final texture was also non-axisymmetric. An examination of the texture heterogeneity was carried out in one of the pure Mg torsion tested samples by subjecting it to EBSD examination at different locations of the surface along the axial direction. The strain induced on the ear portion was maximum, and in the face was lower. This has been attributed to the orientation of basal planes in the two regions. The axisymmetric initial texture in case of the alloy AM30 led to the formation of axisymmetric texture with no change in the shape of the material. Owing to this simplicity, the occurrence of dynamic recrystallization (DRX) was studied in more detail for this alloy. The mechanism of texture development due to deformation as well as dynamic recrystallization could be tracked at every stage of deformation. A typical shear texture was observed with respect to the strain in each case. Very low fraction of twins was observed for all the cases indicating slip dominated deformation, which was validated by VPSC simulation. It was found that with the increase in strain during torsion, the fraction of dynamically recrystallized grains increased. The recrystallization mechanism was classified as “continuous dynamic recovery and recrystallization” (CDRR) and is characterized by a rotation of the deformed grains by ~30⁰ along c-axis. After developing an understanding of large strain deformation behaviour of pure Mg and the alloy AM30 through torsion tests, the possibility of low temperature severe plastic deformation for both the materials by equal channel angular extrusion (ECAE) was explored. The outcome of this investigation has been presented in chapter 5. At first, ECAE of pure magnesium was conducted at 250⁰C up to 4 passes and then the temperature was reduced by 50⁰C in each subsequent pass. In this way, ECAE could be carried out successfully up to 8th pass with the last pass at room temperature. A grain size ~250 nm and characteristic ECAE texture with the fibres B and C2 were achieved. The AM30 alloy subjected to similar processing schedule as pure Mg, however, could be deformed only up to 6th pass (TECAE=150⁰C) without fracture. An average grain size ~ 420 nm and a texture similar to ECAE processed pure Mg was observed for this alloy. The difference in the deformation behaviour of the two alloys has been explained on the basis of the anisotropy in the stacking fault energy (SFE) in the case of pure Mg. Neutron diffraction was carried out to confirm and validate the microtexture results obtained from the EBSD data, while the local texture measurement by synchrotron radiation was carried out at different locations of the ECAE samples to give a proper account of the heterogeneity in texture. The effect of grain refinement was examined, deconvoluting the effect of shear in improving the strength and ductility using another severe plastic deformation technique, namely multi axial forging (MAF). In this process, the material was plastically deformed by a combination of uniaxial compression and plane strain compression subsequently along all the three axes. The details of this investigation has been presented in chapter 6. By this method, the alloy AM30 could be deformed without fracture up to a minimum temperature of 150⁰C leading to ultra-fine grain size (~400 nm) with very weak texture. A room temperature ductility ~55% was observed for this material. Finally, a comparison of room temperature mechanical properties of the alloy AM30 was carried out for the ECAE and MAF processed conditions having similar grain size in order to observe the effect of texture formed during both the processes. A similar strength and ductility for both the cases was attributed to the orientation obtained from both the ECAE and MAF, which is away from the ideal end orientation for tensile tests. The final outcomes of the thesis has been summarized in chapter 7.

Este trabalho tem como objetivo avaliar o efeito do processo de agitação eletromagnética (AE) utilizado no lingotamento contínuo (LC) e nas propriedades mecânicas e metalúrgicas dos aços ABNT 1025 (com adições de manganês e silício) forjados a quente, para a confecção de flanges de tubulações industriais. As matériasprimas fornecidas foram caracterizadas através de composição química e macrografia. Compararam-se os aços provenientes de três condições de fornecimento: 1º) LC sem AE somado à laminação a quente (LQ); 2º) LC com AE; e 3º) LC sem AE. Em seguida, foram extraídos billets de seção quadrada de 120mmx120mmx58mm das três condições citadas para subsequentes forjamentos a quente e fabricação de flanges. Assim, são mostrados os resultados das propriedades obtidas e a comparação com a norma de validação ASTM A 105 (especificação padrão para forjados de aço carbono para aplicação em tubulações) utilizada nesse tipo de forjado. Através da norma, foram verificados os requisitos químicos e ensaios de tração e de dureza. As propriedades foram, também, analisadas através de metalografias (macro e micro), ensaios de impacto e ensaios não destrutivos de líquidos penetrantes. Através da teoria elementar da plasticidade, os valores requeridos para a força de forjamento da peça em estudo, durante o processo de forjamento a quente, foram estimados em caráter formativo e didático. De acordo com os fundamentos teóricos observados na revisão bibliográfica e com os resultados práticos obtidos, constatou-se a aprovação dos aços provenientes do LC com AE como alternativa aos provenientes da LQ (tradicionalmente fornecidos às forjarias) para a confecção de flanges forjados desse tipo de aço. Na análise dos forjados provenientes do LC sem AE também ocorreu a reprovação de diversos resultados, mostrando o efeito da AE como alternativa para as propriedades desse tipo de forjado. / The objective of this work is to evaluate the effect of the process of electromagnetic stirring (ES) used in continuous ingot (CI) in the mechanical and metallurgic properties of 1025 ABNT hot forged steels (with the addition of manganese and silicon) for the manufacture of flanges of industrial pipes. At first, the supplied raw materials were characterized trough chemical compound and macrograph. Then, steels from the following three supplying conditions [ 1º) CI without ES plus hot rolling (HR); 2º) CI with ES; and 3º) CI without ES] were compared. Afterwards, billets were extracted from a square section measuring 120mmx120mmx58mm, from the three previous conditions, to be hot forged and to the manufacture of connection flanges. Thus, the results from these properties and the comparison with the validation norm ASTM A 105 (standard specification for steel-carbon forgings for the application in pipes) for this type of forged are shown. Through this norm, chemical requirements, tension and hardness tests were verified. The properties were also analyzed through metallographies (macro and micro), impact tests and non-destructive tests of penetrating liquids. Through the elementary plasticity theory, the demanded values for the forging force of the studied piece, during the hot forging process, were estimated as didactic and formative natures. According to the theoretical substances observed in the bibliography and to these practical results, the steels from CI with ES were approved as an alternative to the ones from HR (traditionally supplied to forging companies) to the manufacture of forged flanges of this type of steel. Moreover, in the analysis of forgings from CI without ES, the disapproval of various results also occurred, showing the effect of ES as an alternative to the properties of this type of forging.

Este trabalho tem como propósito analisar o modelo matemático baseado na Teoria Elementar da Plasticidade (TEP) para o Forjamento em Matriz Aberta (FMA) de tarugos cilíndricos com o intuito de obter um eixo vazado para a utilização em aerogeradores. Foram realizadas simulações computacionais pelo Método dos Elementos Finitos (FEM) com efeito de comparação, utilizando o software Simufact.Forming 11.0. Foi exposto a sequência de cálculos e as interações realizadas para a construção de um modelo matemático a partir da TEP. Esse modelo matemático foi aplicado para os dois primeiros recalques em um tarugo cilíndrico vazado. Ambos os recalques foram executados no processo de Forjamento em Matriz Aberta. Tanto com o procedimento matemático baseado na TEP, quanto na simulação numérica baseado no FEM, foram obtidos os valores de distribuição de deformações, de distribuição de tensões e de forças de compressão requeridos pela prensa de forjamento para ambos os recalques. Com a conclusão dos experimentos físicos foi constatado que os valores das forças obtidos pela Teoria Elementar da Plasticidade (TEP) e pelo Método dos Elementos Finitos (FEM) variaram aproximadamente entre 5 a 15% em relação aos valores experimentais, possibilitando fazer comparações com variações e alterações na metodologia do processo. Observou-se que as regiões que apresentaram maiores concentrações de deformações equivalentes e tensões na direção z pelo modelo matemático (TEP) coincidiram com as regiões de maiores concentrações encontradas no software de simulação numérica (FEM). Desta forma, estima-se para a geometria estudada que a TEP pode ser empregada como uma ferramenta de simulação eficiente no processo de Forjamento em Matriz Aberta. / This paper aims to analyze the mathematical model based on the Plasticity Elementary Theory (TEP) for the Open Die Forging of cylindrical billets in order to get a hollow shaft for using in wind generator. Computer simulations were performed by the Finite Element Method (FEM) with purpose of comparison, using the software Simufact.Forming 11.0. It was exposed the calculations sequence and performed interactions to make a mathematical model from the TEP. This mathematical model was applied for the first two upsetting in a hollow cylindrical billet. Both upsetting were executed in the process of Open Die Forging. Both the mathematical method based in the TEP as the numerical simulation based in the FEM, it were obtained the value of the strains distribution, the stresses distribution and the compressive force required by the forging press for both upsetting. With the physical experiments concluded, it was found that the forces values obtained by the TEP and by the FEM ranged approximately between 5 and 15% compared to the experimental values, allowing make comparisons with variations and changes in the process methodology. It was observed that regions where showed higher concentrations of equivalent strains and stresses in the z direction by the mathematical model (TEP) coincided with the regions of higher concentrations found numerical simulation software (FEM). It’s demonstrated for the geometry studied that the TEP can be employed as a simulation efficient tool in the process of Open Die Forging.

A conformação mecânica está presente em diversos processos industriais e classificam-se em diversas categorias com base em critérios como: o tipo de esforço que provoca a deformação do material, a variação relativa da espessura da peça, o regime de operação de conformação, a temperatura de trabalho, o propósito da deformação. Basicamente, os processos de conformação mecânica podem ser classificados em: conformação de chapas, extrusão, trefilação, laminação e forjamento. O desempenho dos componentes mecânicos pode ser avaliado por uma série de ferramentas matemáticas, porém o conjunto de soluções analíticas nem sempre atendem a solução do problema, o que leva ao uso de métodos numéricos com soluções aproximadas. Com a evolução tecnológica muito tem se utilizado das simulações computacionais visando obter resultados mais rápidos, confiáveis e econômicos. Muitos métodos tem sido implementados para a realização de simulações e em destaque tem-se a modelagem por elementos finitos. O método dos elementos finitos considera a região de solução do problema formada por pequenos elementos conectados entre si, onde a região em estudo é analiticamente modelada ou aproximada por um conjunto de elementos discretos pré-definidos. A metodologia utilizada, consiste nas definições do produto a ser estampado, processo de conformação, e os projetos das ferramentas que serão utilizadas na fabricação do produto, após estas definições, serão modelados no software Inventor os componentes que atuam diretamente na conformação, em seguida serão inseridos no software DEFORM as ferramentas modeladas, e as informações técnicas referentes ao processo e todas as condições que podem influenciar no trabalho de conformação. Após a realização da simulação, é feita a análise das informações obtidas para que seja avaliada a viabilidade do processo, se o processo se mostrar capaz de atingir as especificações desejadas é dado prosseguimento na fabricação do produto, caso contrário serão feitas revisões e correções para que sejam alcançados as especificações, sem que seja necessário a construção de ferramentas. / The mechanical conformation is present in many industrial processes and are classified into several categories based on criteria such as: the type of stress that causes the deformation of the material, the relative variation of the thickness of the workpiece, the scheme forming operation, the temperature work, the purpose of deformation. Basically, the mechanical forming processes can be classified as: sheet metal forming, extrusion, wire drawing, rolling and forging. The performance of mechanical parts can be assessed by a number of mathematical tools, but the joint analytical solutions do not always meet the problem solution, which leads to the use of numerical methods to approximate solutions. With the technological evolution has long been used computational simulations to obtain results faster, reliable and economic. Many methods have been implemented to carry out simulations and has been highlighted by finite element modeling. The finite element method considers the region of solving the problem consists of small elements connected to each other, where the region under study is analytically approximated or modeled by a set of predefined discrete elements. The methodology used is the product settings to be printed, forming processes, and the tools projects that will be used in the manufacture of the product, after these settings, will be modeled in Inventor software components that act directly on the conformation then be entered into the software DEFORM patterned tools, and technical information related to the process, and all the conditions that may influence on the conformation work. Upon completion of the simulation is made analysis of information to be made to evaluate the process of viability, if the process proves capable of achieving the desired specifications are given further in the manufacture of the product, otherwise revisions and corrections will be made that the specifications are achieved without the build tools required.

Este trabalho apresenta um estudo relacionado a três estados de superfície aplicados em um substrato de aço ferramenta AISI H13 temperado e revenido utilizado no processo de calibração a frio para a fabricação de forjados de precisão, os quais posteriormente processados transformam-se em componentes de um semieixo homocinético. O foco deste trabalho foi demostrar através da aplicação de tratamentos de superfície o aumento do desempenho em termos de resistência ao desgaste na interface da superfície da ferramenta em análise e também correlacionar com o seu custo benefício do produto final, visto que o critério para avaliação de vida útil depende diretamente do dimensional final do forjado. Para a comparação e o teste industrial foram estipuladas três condições diferentes de superfície para serem avaliadas. A primeira sem revestimento, a segunda com modificação superficial pelo processo de nitretação gasosa e a terceira com revestimento Dúplex PVD a base de CrTiN. A caracterização das amostras foram realizadas com o auxílio de microscopia eletrônica de varredura, análises metalográficas de microestrutura e dureza. A partir dos resultados obtidos foi constatado que o revestimento Dúplex aplicado em ferramentas para calibração a frio apresentou o melhor desempenho em relação às outras duas condições propostas. O revestimento Dúplex obteve um ganho de 400% em vida útil de ferramentas correlacionado a melhor resistência ao desgaste e, além disso, uma melhor performance em seu comportamento dimensional perante ao processo aplicado. Como segunda alternativa, as ferramentas com o processo de nitretação gasosa atingiram uma redução de 17% nos custos de ferramentas por peças produzidas e acréscimo de 20% em vida útil de ferramentas, apresentando uma melhora em relação as ferramentas sem tratamento de superfície. / This work presents a study related to three surface states applied on a quenching and tempered AISI H13 tool steel substrate used in the cold calibration process for the manufacture of precision forgings, which are subsequently processed into components of a halfshafts. This dissertation aims at demonstrating, through the application of surface treatments, the increase in the wear resistance performance of the tool under analysis and correlating this with cost benefit in the final product, since the end life criterion for the tools depends directly on the dimensions of the forged part. For comparison and industrial testing three different surface conditions were stipulated for evaluation. The first uncoated, the second with surface modification by the gas nitriding process and the third with PVD duplex coating based on CrTiN. The characterization of the samples was carried out with Optical and Scanning Electron Microscopy, Metallographic Analysis of the Microstructure and Hardness Tests. According with obtained results it was verified that the treatment duplex coating applied in tools for cold calibration presented the best performance in relation to the other two conditions proposed. The duplex coating obtained a gain of 400% in tool life correlated to better resistance to wear and, in addition, a better performance in its dimensional behavior in relation to the previous condition without surface treatment. As a second alternative, the tools treated by the gas nitriding process achieved a 17% reduction in tooling costs per parts produced and a 20% increase in tool life, showing an improvement over tools without surface treatment.

The diploma thesis deals with the optimization of final position of overlaps on a forged cam. This part is manufactured in Šroubárna Kyjov, spol. s r.o. The cam is made from ČSN 14 109 (100Cr6) steel. The thesis is focused on the optimization of overlaps arising due to pressed burrs on the edges of the semifinished forging. Currently, the final position of these overlaps is very close to the edge of the pre-forged hole of the cam. Undesired chipping of material occurs during machining of the hole to the exact dimension. The final position of the overlaps is optimized by using the numerical simulation in Simufact Forming 15.0, including a verification simulation for optimal parameter settings. Various diameters of semifinished products, turned tools, and modification of shapes of the tools are tested in the thesis to prevent occurrence of the overlaps in undesired positions.

This diploma thesis deals with the influence of graded deformation of 8Cr3MoV steel rolling mills on the structure and mechanical properties. The theoretical part of this thesis describes general requirements for rolling mills, commonly used material, and the making of hot rolling mill rolls with emphasis on 8Cr3MoV steel. The second part is a report on experimental material and used methods. Then the results are presented. The influence of distance from the longitudinal axis of ingot and graded deformation on the forged shaft on the structure and mechanical properties are discussed at the end of this thesis, as well as a comparison of structure and mechanical properties of ingot and forged shaft.

This Diploma thesis deals with design technology of alternator claw pole. The technology is designed to achieve low production costs. The purpose is to prevent the transfer of manufacturing contract to countries with cheap manpower and low production costs. Technology design is done by selecting billets to the processing and economic evaluation. The dominant technology is a cutting operation that is performed on numerically controlled machines.

Taking into account modern technology solutions has been selected die forging of the wheel hub of automobile steel 14220 (DIN 16MnCr5) about the serial 50000 pcs. Based on the literature study and practical experience has been solved forging process, including technological calculations, engineering drawings and results of simulations of the forging process performed by the Qform software tool. A tool was designed to be made of 19552 grade alloy tool steel. The forged piece is to be forged on an LZK 1000 crank press with the nominal forming force of 10 MN manufactured by Šmeral Brno. The stock is divided with shears from bar 45 mm 6 m long to bar 89.5 mm long.