This thesis deals with questions concerning the sedentary settlement in central Norrland: its origins, function and development. This type of settlement appears at the start of our calendar. The material comprises an almost fully excavated farmstead from the Early Iron Age (1-600 A.D.), situated on Genesmon in the parish of Själevad, northern Ångermanland. Particular stress has been put on the description of the individual structures and on questions concerning the construction and room-division of the houses. The farm's resource utilization, handicrafts and development are also analysed and discussed.The basic material for the thesis has been obtained through archaeological excavations. To a limited degree a comparative method has been used with regard to the form and content of the farm settlement. In addition data has been extracted from the presence, distribution and species of carbonized seeds, which were collected from post-holes, hearths and other features in and around the nine house foundations found hitherto.Contrary to the views of previous research, the results show that even northern Ångermanland obtained sedentary settlement at about the same time as Hälsingland and Medelpad. With regard to the origin of this settlement a critical examination is made of previous research, which has largely been in agreement that it was a result of colonization from the Mälar Valley. Some circumstances are presented which can be interpreted rather as internal development under influence. The settlement on the excavated site at Gene consists of a farmstead, with a three-aisled long-house and smaller three-aisled houses nearby with special functions. The number of small houses increases with time. Only a few remnants of dividing walls have been encountered. Room analyses show that the long-house was probably divided into six rooms or sections, each with its own function. The general layout and this room-division corresponds well with other contemporary houses in, for example, S.W. Norway and on Jutland. There are however tendencies towards regional differences. During the Migration Period both iron-forging and bronze-casting have taken place on the farm. These handicrafts were probably not carried out by professional smiths. The remains of bronze working show that relief brooches, keys, rings and pins were cast. A preliminary going-through of the literature also shows that bronze-casting was considerably more common on the Migration Period farms in Norden than one generally assumed. The farm on Genesmon is suggested to have been relocated during the 6th or 7th century A.D. Since a similar restructuring or movement of settlement can be noted over large parts of Norden during this period, the explanations for the relocation of the Gene farm must be sought in changes in a long-established inter-regional structure. / digitalisering@umu

Neste trabalho foram avaliadas as condições de processamento e caracterização da liga 66Co-28Cr-6Mo utilizada em implantes. Cada lingote foi produzido por meio de fusão a arco voltáico, sob atmosfera de argônio em um cadinho de cobre refrigerado à água. Os resultados foram comparados com aqueles de uma barra da liga 66Co-28Cr-6Mo comercial. A temperatura de forjamento a quente da liga é em torno de 1200º C, pois temperaturas menores levam a fraturas do material no decorrer do forjamento. Na análise química realizada na liga 66Co-28Cr-6Mo obteve-se uma concentração de 0,038%C, ou seja, esta concentração encontrada nos lingotes da liga 66Co-28Cr-6Mo produzida estão dentro das especificações da norma ASTM F1537 para a liga com baixo teor de carbono (0,14%C). Os lingotes apresentaram uma microestrutura policristalina, com presença de defeitos volumétricos (poros) possívelmente advindos do processo de solidificação. Foram realizados ensaios de oxidação nas temperaturas de 1200 oC, 1100 oC, 1000 oC e 900 oC por cerca de 30 minutos para avaliar o grau de oxidação da liga de 66Co-28Cr-6Mo em elevadas temperaturas, pois a conformação mecânica da liga é realizada a quente conforme descrito na norma ASTM F1537. O limite de escoamento à tração da liga 66Co-28Cr-6Mo na condição bruta é em média de 750 MPa e o módulo de elasticidade da mesma liga é, aproximadamente de 158 GPa. Notou-se na liga 66Co-28Cr-6Mo comercial uma microestrutura com grãos refinados, proveniente do processo de forjamento a quente. Além disso, observa-se a presença de maclas, porém não se pode afirmar se este defeito é devido à deformação plástica ou tratamento térmico. O limite de escoamento à tração da liga 66Co-28Cr-6Mo comercial foi de 975 MPa e módulo de elasticidade é, de aproximadamente de 203 GPa. A densidade de corrente de corrosão das ligas 66Co-28Cr-6Mo produzida e comercial são respectivamente 1,9x10-7 e 1,5x10-7 Acm-2. Estes valores indicam uma alta resistência à corrosão de ambas as ligas em solução de Ringer. As amostras das ligas 66Co-28Cr-6Mo comercial e produzida apresentaram uma curva de viabilidade celular acima da linha do índice de citotoxicidade (IC50%) = 50%, ou seja, as ligas são consideradas não tóxica. / In this study we evaluated the processing conditions and characterization alloy 28%Cr 66%Co-6%Mo used in implants. Each ingot was produced by through arc melting arcing under argon atmosphere in a water-cooled copper crucible. The results were compared with those of a commercial bar 66Co-28Cr-6Mo alloy. The temperature of hot forging 66Co-28Cr-6Mo alloy should be around 1200 º C because lower temperatures lead to fracture of the material during forging. In the chemical analysis performed on the alloy 66Co-28Cr-6Mo obtained a concentration 0,038 %C. Indeed the alloy 66Co-28Cr-6Mo produced are within the specifications of ASTM F1537 for the alloy with low carbon (0.14% C). The ingots had a polycrystalline microstructure with the presence of volumetric defects (pores) possibly arised from the solidification process. Oxidation tests were carried out at temperatures of 1200 oC, 1100 oC 1000 oC and 900 oC for about 30 minutes to evaluate the degree of oxidation of 66Co-28Cr -6Mo alloy at high temperatures because of the mechanical forming league will be held hot. The tensile yield strength of the 66Co-28Cre-6Mo alloy is provided and gross average of 750 MPa and elasticity of the same alloy is approximately 158 GPa. It was noted in the 66Co-28Cr-6Mo alloy commercial grain microstructure with a refined, from the hot forging process. Moreover, observed the presence of twinned, but one cannot say whether this defect is due to plastic deformation or heat treatment. The tensile yield strength of the 66%Co-28%Cr-6%Mo alloy trade was 975 MPa and modulus of elasticity is of approximately 203 GPa. The corrosion current density of the 66Co-28Cr-6Mo alloys and commercial produced are respectively 1,9.10-7 and 1,5.10-7 Acm-2. These values indicate a high corrosion resistence of both alloys in Ringer\'s solution. Samples of the commercial and produced 66Co-28Cr-6Mo alloys a curve above the cell viability index of citotoxicity (IC50%) = 50% the alloys are considered non-toxic.

Orientador: Maria Helena Robert / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-11-08T18:37:47Z (GMT). No. of bitstreams: 1 Delbin_Daniel_M.pdf: 8551361 bytes, checksum: 770e9d00eeb959cc6e40cf3f314faa4e (MD5) Previous issue date: 2006 / Resumo: Neste trabalho é estudada a viabilidade de produção de esponjas metálicas pela conformação de pasta tixotrópica da liga A2011, sobre camada de agente bloqueador (NaCl) posteriormente removido para formação da porosidade. Investiga-se a influência da temperatura de tratamento térmico, para obtenção da pasta semi-sólida, e da granulometria do agente bloqueador, na estrutura formada do material celular (aspecto geral, caracterização qualitativa e quantitativa dos poros, microestrutura da parede celular e densidade) e nas características de processo (forças de tixoforjamento e capacidade de penetração da pasta). São produzidos cilindros de material poroso metálico tipo sanduíche, compostos de camada porosa entre camadas maciças da liga, com três diferentes classes de porosidade: fina, média e grosseira. As esponjas foram submetidas à tomografia computadorizada e à análise metalográfica para sua caracterização estrutural. Os resultados obtidos mostram a viabilidade de obtenção de esponjas metálicas utilizando a tecnologia de semi-sólidos e o tipo de bloqueador utilizado. O sucesso do processo depende da fração líquida presente na pasta metálica tixotrópica, reduzida fração líquida pode resultar em incompleta infiltração e compressão das partículas do agente bloqueador. Nas condições analisadas a granulometria do agente bloqueador não teve influência sensível na qualidade do produto. A densidade do material poroso aumenta com o aumento da temperatura de processo, devido ao aumento da espessura de paredes metálicas na estrutura porosa / Abstract: The work analyses the possibility of the production of cellular material by pressing the A2011 alloy in the thixotropic semi-solid state, into a space holder pre-form. Space holder particles used are NaCl, which are removed from the product after the forming operation, resulting the porous material. It is investigated the influence of the thixoforming temperature and the size of space holder particles, in the structure of the obtained porous material (general aspect, quantitative and qualitative characterization of porosity, microstructure of cell walls and density of the product), as well as in the processing characteristics (required forces for infiltration, penetration ability of the slurry in the salt pre-form). Cylindrical samples, sandwich type, with a porous layer inserted between layers of compact alloy are produced, presenting three different ranges of porosity. The cellular material obtained contains opened porosity, being characterized as sponge. Products were analyzed by tomography and metallographic techniques. Results show that the proposed process is able to produce acceptable porous material, with a simple and low cost technique. The quality of the product depends rather on the processing temperature than on the size of space holder particles. Low liquid fraction in the thixotropic slurry can lead to incomplete infiltration and deformation of the pre-form. In the analyzed conditions, influence of the size of space holder particles could be observed neither in the processing ability nor in the quality of the product. Density of produced porous material increases as processing temperature increases, due to the increase of thickness of cell walls / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Le forgeage multi-matériaux est un procédé permettant la mise en forme et l’assemblage simultanés de matériaux différents. Ce procédé permet d’obtenir des pièces multi-matériaux avec le « bon matériau placé au bon endroit ». L’objectif des travaux de thèse est de définir les conditions nécessaires à l’établissement de la liaison métallurgique par forgeage à l’interface d’un couple d’aciers. Dans un premier temps, l’état de l’art a servi à l’identification les phénomènes physiques accompagnant le forgeage multi-matériaux et les paramètres clés pilotant l’établissement de la liaison métallurgique. Le principe de base de l’établissement d’une liaison passe par la fragmentation des oxydes en surface des matériaux et par l’application d’une pression de contact favorisant le contact entre les matériaux nus et la diffusion. Les deux paramètres clés identifiés sont donc la pression normale de contact et l’expansion de surface. Le protocole de caractérisation du co-forgeage mis en place comporte trois essais « simples » permettant de solliciter les interfaces avec des pressions et des expansions différentes. Ces dernières, estimées par simulation numérique de l’essai, sont mises en relation avec la qualité des liaisons obtenues évaluée, quant à elle, au travers d’observations métallographiques. Les premières simulations permettent de dimensionner les campagnes expérimentales. Celles-ci sont ensuite conduites sur les moyens de mise en forme de la plateforme VULCAIN. Les efforts de mise en forme et la géométrie globale des pièces et la répartition de matière servent de base à l’identification des paramètres de la simulation. La simulation ainsi obtenue et les observations métallographiques aux interfaces sont ensuite mises en lien. Cette démarche a permis de confirmer l’importance du rôle joué par la pression de contact et l’expansion de surface sur l’établissement d’une liaison au cours de la mise en forme du multi-matériaux. La répartition et la forme des particules d’oxydes semblent liées au chemin thermomécanique subi par l’interface. / The multi-material forging is a forming process allowing, simultaneously, the welding and shaping of multi-material parts with the right material at the right place. The purpose of the presented work is to identify the necessary conditions to obtain a metallurgical bond during forming between two different grades of steel. First, the state of the art allowed the identification of the physical phenomena occurring during multi-material forging and the determination of the key parameters of the bonding which are the contact pressure and the surface expansion at the both sides of the interface. The mechanisms to establish metallurgical bond by forging are based on the breaking and the dispersion of the oxide layer at the interface then the extrusion of the soft material through the voids generated between the oxide fragments. Second, the characterization methodology of this work is presented. It consists of three “simple” forming tests leading to different interface conditions (contact pressure and surface expansion). The first simulations allow the design of the experimental plan for each test. The comparison between simulations and experiments allows the identification of physical parameters of the simulation. Then, the contact pressure and the surface expansion of the identified simulations are used to analyze the metallographic structure and the bonding at the interface.The developed work confirms the major effect of the contact pressure and the surface expansion on the establishment of a metallurgical bond during multi-material forming. The size and the shape of the oxide particles seem to depend on the thermomechanical path at the interface.

<p>Rapporten beskriver en undersökning rörande två olika typer av inre fel, centrumfel och ytnära fel, på valsar. Examensarbete för högskoleingenjörsexamen i maskinteknik (22.5p) vid Instutitionen för ingenjörsvetenskap, fysik och matematik, Karlstad Universitet. Utfört på uppdrag av Scana Steel Björneborg AB.</p><p>Scana Björneborg är en av Europas ledande producenter av tunga friformsmidda detaljer och har eget stålverk, egen smedja, värmebehandlingsanläggning och maskinpark. På Scana Björneborg gjuts göt av järnskrot, varpå de smids, värmebehandlas och maskinbearbetas till valsar. Efter maskinbearbetning kontrolleras valsarna med ultraljud för att hitta eventuella inre fel. Specifikationerna från kund för hur stora indikationer får vara är strama och stora kostnader uppstår i samband med reklamationer, kassationer, omarbeten och förseningar. Felen har blivit alltmer frekventa och Scana Björneborg har satt samman två projektgrupper för att få försöka få bukt på dem. Examensarbetet skall understödja båda dessa grupper och genom undersökningen skapa underlag för vidare beslut. Undersökningen delades in i tre olika moment:</p><p>* Statistik och information som kunde användas för att hitta eventuella samband och orsaker till de olika feltyperna samlades i en databas.</p><p>* Den samlade statistiken och informationen organiserades, förenklades och analyserades sedan med hjälp av programmet SIMCA, ett program gjort för multivariata analyser av stora datamängder. Eventuella samband granskades och analyserades därefter manuellt för att väga och gallra resultatet .</p><p>* Sex ytnära fel i tre olika detaljer öppnades upp för kartläggning av vilken typ av defekter det rörde sig om, och en metallografisk undersökning i ljus- och svepelektronmikroskop och analys av defekternas sammansättning gjordes.</p><p>SIMCA-analys av insamlad statistik med avseende på centrumfel och vidare granskning och analys av dess resultat antyder att hög smidesvikt, hög Vanadinhalt, stukning, hög nedsmidningsgrad och smidestid per ton i den följden är viktiga faktorer vid uppkomsten av centrumfel, och att en viss samverkan finns mellan dem.</p><p>SIMCA-analys av insamlad statistik med avseende på ytnära fel och vidare granskning och analys av dess resultat antyder att ett samband mellan valda parametrar och uppkomsten av ytnära fel inte går att hitta. Metoden bedöms olämplig för vidare undersökning av ytnära fel.</p><p>Den metallografiska undersökningen av öppnade ytnära defekter visade att samtliga sex defekter liknade varandra till utseende och sammansättning. Vanligaste beståndsdelarna i dessa inneslutningar var Aluminium tillsammans med förhöjda halter av Kol och Syre. Dessa ämnen är alla naturliga i stålet och därför bedöms inte de ytnära felen vara utifrån kommande.</p> / <p>The report describes an investigation concerning two types of internal defects, axis-centered defects and near-surface defects, in rolls. Thesis for bachelor’s degree in mechanical engineering (22.5p), at the institution for engineering, physics and mathematics, Karlstad University. Ordered by Scana Steel Björneborg AB.</p><p>Scana Steel Björneborg AB is one of Europe’s leading producers of heavy free-form forgings and has its own steel plant, forge, heating treatment facility and machine park. Scana Steel Björneborg AB casts ingots from iron scrap. The ingots are then forged, heat treated and machined into rolls. After the machining the rolls are tested with ultrasonic testing equipment to look for indications of internal defects. The specifications on how big the indications are allowed to be from the client are rigid and large costs come up because of reclamations, discarding, reworking and delays. The defects have become increasingly more frequent and Scana Steel Björneborg AB has put together two groups to try and get control over the problem. The thesis is meant to support the two groups by investigating the internal defects, and to create a platform to take further decisions from. The investigation was made up of three parts:</p><p>* Statistics and information that could be used to find connections and cause of the internal defects was gathered in a data base.</p><p>* The gathered statistics and information was organized, simplified and analyzed with SIMCA, a computer software made for multivariate analyzing of large amounts of information. The results of the SIMCA-simulation were then checked further manually to weigh and lay down the fairness of the results.</p><p>* Six near-surface defects in three parts were opened up to map the types of defects and a metallographic examination in optical microscope, scanning electron microscope and spectrometer analysis of the defects’ composition was made.</p><p>The SIMCA analysis of gathered statistics concerning axis-centered defects and later manual analysis of the results showed that high forging weight, high Vanadium content, high degree of forging and low forging-time per tonne all relate to the creation of axis-centered defects, and that some interaction is present between them.</p><p>The SIMCA analysis concerning near-surface defects showed that the chosen parameters do not relate with the creation of near-surface defects. The method is deemed unsuitable for further investigations.</p><p>The metallographic examination of the six near-surface defects showed that all six defects resemble each other in appearance and composition. The most common elements in these inclusions are Aluminum and heightened contents of Carbon and Oxygen. These elements are all naturally occurring elements in the steel and because of this the inclusions are not thought to be exogenous.</p>

Le second chapitre introduit les différents couplages présents dans une analyse mécanique thermique métallurgique. Il rappelle ensuite les notions de métallurgie nécessaires à la compréhension de ce travail. Le troisième chapitre décrit la modélisation adoptée pour l'analyse thermique métallurgique non couplée au problème mécanique. Le modèle choisi est celui de FERNANDES (CP30). Le code développé par ce dernier était limité à l'étude de cylindres infiniment longs, c'est-à-dire à un problème unidimensionnel. L'intégration de ce modèle, dans le code LAGAMINE apporte une grande liberté quant aux formes géométriques traitées. Actuellement, les cas bidimensionnels (état plan ou axisymétrique) peuvent être traités, une extension aux cas tridimensionnels ne pose pas de problème si ce n'est celui des temps de calcul. Du point de vue théorique, nous avons proposé une formulation différentielle de la modélisation des transformations par diffusion. Cette approche, indépendante de celle de SJOSTROM (CP38) a permis de vérifier cette dernière par une voie différente. En outre, la comparaison de cette approche avec celle plus classique de FERNANDES constitue un élément nouveau intéressant. Pour terminer, des tests de validation des développements correspondants dans le code LAGAMINE sont présentés. Le chapitre quatre est consacré aux problèmes numériques à résoudre pour réaliser une simulation de refroidissement d'une pièce métallique. Une bibliographie des schémas d'intégration temporelle des problèmes thermiques linéaires et non linéaires est présentée. A ce niveau, nous ne pouvons parler de contribution originale puisqu'il s'agit de schémas devenus classiques. Cependant, il est assez rare de trouver un résumé de ces notions souvent dispersées dans de nombreux articles. A ce titre, nous considérons ce point comme un apport intéressant de cette thèse. La prise en compte des changements de phase a occasionné un grand nombre de recherches. Après avoir fait le point sur les méthodes proposées par la littérature, nous décrivons les développements introduits dans le code LAGAMINE. Le calcul des flux et de la matrice tangente est détaillé. Ce dernier point constitue un apport personnel original, surtout au niveau de la contribution des transformations de phase à la matrice tangente. Le chapitre cinq est consacré aux interactions existant entre les phénomènes mécaniques, thermiques et métallurgiques. Une présentation approfondie de chaque couplage est réalisée et la notion de plasticité de transformation est introduite. Notre contribution personnelle et originale réside dans :  une loi élasto-plastique thermique couplée pour un matériau monophasique,  une loi élasto-plastique thermique métallurgique pour un matériau multiphasique. L'intégration des lois élasto-plastiques thermiques, métallurgiques ou non, dans le code LA GAMINE constitue le chapitre six. Les points suivants constituent un apport original de cette thèse:  schéma d'intégration temporelle de base pour ces lois couplées,  apport des sous-intervalles d'intégration,  étude de la matrice tangente couplée d'un élément isoparamétrique à 8 nuds,  amélioration du schéma d'intégration temporelle de base pour assurer la stabilité en cas de transformation martensitique,  développement de la notion d'état plan généralisé pour l'étude du refroidissement d'une poutrelle métallique. Le chapitre sept présente le problème du remaillage. Après une description succincte des solutions proposées par la littérature, nous justifions notre choix d'un remaillage avec maillage indépendant. Ce dernier semble en effet le mieux adapté aux problèmes de forgeage et d'estampage que nous désirons résoudre. Le chapitre huit est consacré à la détermination de l'instant opportun pour réaliser un remaillage. Nous distinguerons deux types de critères: a. les critères avec estimation de l'erreur, développés dans le cadre de l'optimisation des maillages d'éléments finis lors d'une analyse linéaire, ou adaptés aux problèmes non linéaires de formage des métaux, b. les critères sans estimation de l'erreur, basés sur des mesures de distorsion des éléments, les valeurs propres, les mesures des interpénétrations de la pièce forgée et de la matrice. Concernant les critères du type a, notre contribution personnelle est la suivante:  étude bibliographique traduisant dans un vocabulaire d'ingénieur, les développements mathématiques souvent présents lors des études d'estimateurs d'erreur,  adaptation du critère proposé par ZIENKIEWICZ aux lois élastoviscoplastiques présentes dans LAGAMINE et essai d'une variante basée sur une idée personnelle. Concernant les critères de type b, nous proposons des mesures de distorsions originales pour un élément isoparamétrique plan à 8 nuds et nous présentons une analyse des valeurs propres de la matrice tangente. Pour terminer, nous présentons une comparaison des critères de type a et b programmés dans LAGAMINE. A notre connaissance, une telle comparaison n'avait encore jamais été réalisée. Elle nous permet de vérifier la concordance des deux approches. Les avantages et inconvénients de chacune de ces méthodes sont établis. Ils permettent de réaliser un choix des critères à conserver dans l'optique d'un remaillage automatique. Le chapitre neuf présente succinctement la création du nouveau maillage. Les exigences relatives à un mailleur automatique adapté au problème de remaillage sont précisées. Une première approche fut réalisée par nos soins grâce à un programme interactif REMDATA. Les développements originaux de ce programme sont détaillés en annexe 3. Le chapitre dix traite le transfert des informations de l'ancien maillage au nouveau maillage. A ce niveau, deux types d'informations sont considérés: a. les informations relatives aux éléments de solide, b. les informations relatives aux éléments modélisant le contact Le transfert des informations de type a est une opération souvent traitée par la littérature. Après une revue bibliographique des méthodes proposées, nous présentons une méthode originale et personnelle de transfert. Ses qualités principales sont sa précision, sa facilité de mise en uvre et sa souplesse d'utilisation. Une comparaison de cette méthode avec deux autres méthodes basées respectivement sur les moindres carrés et sur l'extrapolation nodale des valeurs aux points d'intégration est présentée. Concernant les informations de type b, nous n'avons trouvé aucune référence qui traitait leur transfert d'un maillage à l'autre. Ce point est cependant important, comme le montrent des essais de remaillage réalisés sans interpolation de ces variables. Les deux méthodes de transfert présentées dans cette thèse montrent l'évolution de notre approche de ce problème. Toutes deux constituent des apports personnels et originaux. Le chapitre onze présente cinq exemples d'application des développements réalisés: 1. l'analyse thermique métallurgique d'une poutrelle métallique refroidie par arrosage et refroidissement naturel, 2. l'analyse thermique métallurgique mécanique d'une poutrelle métallique refroidie par arrosage et refroidissement naturel, 3. l'analyse thermique métallurgique mécanique de la trempe d'un cylindre en acier 60NCD11, 4. la simulation de l'estampage d'une aube de turbine (analyse mécanique avec remaillage), 5. la simulation de l'estampage d'un pignon de machine (analyse mécanique avec remaillage). Hormis l'application 3 qui constitue l'application du code à un cas test déjà traité par DENIS et SJOSTROM (CP31), ces exemples constituent des contributions originales. Quelques conclusions sont proposées au chapitre douze. Parmi nos contributions originales, certaines nous semblent d'une ampleur et d'un intérêt plus grands :  la loi élastoplastique thermique métallurgique et son schéma d'intégration prennent en compte les couplages existant entre les différents phénomènes. Le nombre de codes réalisant une telle analyse est assez réduit alors que des calculs réalistes de contraintes résiduelles de trempe, de soudure ne peuvent être obtenus par des analyses découplées. De plus, l'adaptation des modèles développés à d'autres traitements thermiques (revenu n.) constitue de nouvelles perspectives de recherches pour l'équipe de M.S.M.,  une présentation des estimateurs d'erreur disponibles dans le cadre de la méthode des éléments finis est une information précieuse pour les ingénieurs numériciens comme pour les industriels qui ont recours à ces calculs,  les différents avantages et inconvénients des critères de remaillage basés respectivement sur les estimateurs d'eITeur et les mesures des distorsions des éléments constituent un élément important pour ceux qui doivent faire un choix entre ces deux types de critères,  l'importance du transfert des informations relatives au contact a été mis en évidence, alors que ce sujet n'est pas abordé dans la littérature.

Rapporten beskriver en undersökning rörande två olika typer av inre fel, centrumfel och ytnära fel, på valsar. Examensarbete för högskoleingenjörsexamen i maskinteknik (22.5p) vid Instutitionen för ingenjörsvetenskap, fysik och matematik, Karlstad Universitet. Utfört på uppdrag av Scana Steel Björneborg AB. Scana Björneborg är en av Europas ledande producenter av tunga friformsmidda detaljer och har eget stålverk, egen smedja, värmebehandlingsanläggning och maskinpark. På Scana Björneborg gjuts göt av järnskrot, varpå de smids, värmebehandlas och maskinbearbetas till valsar. Efter maskinbearbetning kontrolleras valsarna med ultraljud för att hitta eventuella inre fel. Specifikationerna från kund för hur stora indikationer får vara är strama och stora kostnader uppstår i samband med reklamationer, kassationer, omarbeten och förseningar. Felen har blivit alltmer frekventa och Scana Björneborg har satt samman två projektgrupper för att få försöka få bukt på dem. Examensarbetet skall understödja båda dessa grupper och genom undersökningen skapa underlag för vidare beslut. Undersökningen delades in i tre olika moment: * Statistik och information som kunde användas för att hitta eventuella samband och orsaker till de olika feltyperna samlades i en databas. * Den samlade statistiken och informationen organiserades, förenklades och analyserades sedan med hjälp av programmet SIMCA, ett program gjort för multivariata analyser av stora datamängder. Eventuella samband granskades och analyserades därefter manuellt för att väga och gallra resultatet . * Sex ytnära fel i tre olika detaljer öppnades upp för kartläggning av vilken typ av defekter det rörde sig om, och en metallografisk undersökning i ljus- och svepelektronmikroskop och analys av defekternas sammansättning gjordes. SIMCA-analys av insamlad statistik med avseende på centrumfel och vidare granskning och analys av dess resultat antyder att hög smidesvikt, hög Vanadinhalt, stukning, hög nedsmidningsgrad och smidestid per ton i den följden är viktiga faktorer vid uppkomsten av centrumfel, och att en viss samverkan finns mellan dem. SIMCA-analys av insamlad statistik med avseende på ytnära fel och vidare granskning och analys av dess resultat antyder att ett samband mellan valda parametrar och uppkomsten av ytnära fel inte går att hitta. Metoden bedöms olämplig för vidare undersökning av ytnära fel. Den metallografiska undersökningen av öppnade ytnära defekter visade att samtliga sex defekter liknade varandra till utseende och sammansättning. Vanligaste beståndsdelarna i dessa inneslutningar var Aluminium tillsammans med förhöjda halter av Kol och Syre. Dessa ämnen är alla naturliga i stålet och därför bedöms inte de ytnära felen vara utifrån kommande. / The report describes an investigation concerning two types of internal defects, axis-centered defects and near-surface defects, in rolls. Thesis for bachelor’s degree in mechanical engineering (22.5p), at the institution for engineering, physics and mathematics, Karlstad University. Ordered by Scana Steel Björneborg AB. Scana Steel Björneborg AB is one of Europe’s leading producers of heavy free-form forgings and has its own steel plant, forge, heating treatment facility and machine park. Scana Steel Björneborg AB casts ingots from iron scrap. The ingots are then forged, heat treated and machined into rolls. After the machining the rolls are tested with ultrasonic testing equipment to look for indications of internal defects. The specifications on how big the indications are allowed to be from the client are rigid and large costs come up because of reclamations, discarding, reworking and delays. The defects have become increasingly more frequent and Scana Steel Björneborg AB has put together two groups to try and get control over the problem. The thesis is meant to support the two groups by investigating the internal defects, and to create a platform to take further decisions from. The investigation was made up of three parts: * Statistics and information that could be used to find connections and cause of the internal defects was gathered in a data base. * The gathered statistics and information was organized, simplified and analyzed with SIMCA, a computer software made for multivariate analyzing of large amounts of information. The results of the SIMCA-simulation were then checked further manually to weigh and lay down the fairness of the results. * Six near-surface defects in three parts were opened up to map the types of defects and a metallographic examination in optical microscope, scanning electron microscope and spectrometer analysis of the defects’ composition was made. The SIMCA analysis of gathered statistics concerning axis-centered defects and later manual analysis of the results showed that high forging weight, high Vanadium content, high degree of forging and low forging-time per tonne all relate to the creation of axis-centered defects, and that some interaction is present between them. The SIMCA analysis concerning near-surface defects showed that the chosen parameters do not relate with the creation of near-surface defects. The method is deemed unsuitable for further investigations. The metallographic examination of the six near-surface defects showed that all six defects resemble each other in appearance and composition. The most common elements in these inclusions are Aluminum and heightened contents of Carbon and Oxygen. These elements are all naturally occurring elements in the steel and because of this the inclusions are not thought to be exogenous.

La conception de machines électriques tend à intégrer l’impact des procédés de fabrication dans le but d’optimiser la conversion d’énergie mécanique en énergie électrique, en lien avec la maîtrise des propriétés électromagnétiques des composants des machines. Les interactions entre procédés, propriétés électromagnétiques et autres propriétés du matériau ont beaucoup été étudiées dans le cas des tôles compte tenu de leur large utilisation dans le domaine de l’électrotechnique et des moyens de caractérisation magnétique normalisés actuels. Cependant, un alternateur à griffes, utilisé dans l’industrie automobile, comporte des composants massifs au rotor pour la conversion mécanique/électrique. Ces composants, appelés roues polaires, sont obtenus par un processus de fabrication comprenant des opérations de forgeage et dont l’impact sur les performances de la machine est encore mal déterminé. Les nouvelles problématiques que pose ce genre de pièces ont mené, dans le cadre des présents travaux, au développement d’une méthodologie spécifique comprenant : l’identification du lien procédés – produit, le développement d’un banc de caractérisation magnétique d’échantillons représentatifs ainsi que la construction de lois de comportement sur des paramètres matériau pertinents à partir de ces échantillons. Les résultats, en accord avec la littérature, ont montré un impact fort de la déformation plastique et de la taille de grain sur les propriétés magnétiques. Cela se traduit, une fois les propriétés modifiées intégrées dans la simulation des performances d’un alternateur, par une baisse significative du courant débité. / The design of electrical machines aims to integrate the impact of the manufacturing process in order to optimize the conversion from mechanical to electrical energy, with the consideration of the electromagnetic properties of the machine components. The interactions between processes, electromagnetic properties and other material properties have been well studied in the case of the steel laminations, regarding their wide use in electrical engineering and the current standards of magnetic characterization devices. However, the claw pole alternator used in automotive industry has a rotor with massive components for the mechanical-to-electrical energy conversion. These components, called claw poles, are manufactured with forging operations whose impact on the machine performance is yet not well determined. The new challenges brought by this kind of work pieces led, in the frame of the current study, to the development of a specific methodology involving: identification of the link process – product, designing of a magnetic characterization device specific for representative samples as well as the establishment of behavior laws regarding relevant material parameters. The results, in accordance with the literature, have shown a strong influence of plastic strain and grain size on magnetic properties. Once these modified properties integrated in the electromagnetic model of the claw pole alternator, a significant decreased of the output current is eventually observed.

Submitted by Haroudo Xavier Filho (haroudo.xavierfo@ufpe.br) on 2016-04-05T15:14:16Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE PARA O DEPÓSITO PDF.pdf: 2900383 bytes, checksum: ce72e0d7b6e5c9b80143aacc757d6966 (MD5) / Made available in DSpace on 2016-04-05T15:14:16Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE PARA O DEPÓSITO PDF.pdf: 2900383 bytes, checksum: ce72e0d7b6e5c9b80143aacc757d6966 (MD5) Previous issue date: 2012-11-26 / FACEPE / A passagem do século XVIII para o XIX é uma das mais importantes para a compreensão do que somos na contemporaneidade. Koselleck afirma que o intervalo de 1750 a 1850 diz respeito a um tempo cindido: não mais nos encontrávamos nos primeiros passos de uma modernidade incipiente, mas ainda não havíamos alcançado a plena racionalização anunciada pelas ‘Luzes’. Esse conflito reflete-se exemplarmente nas primeiras décadas de prática de impressões de imagem por luz solar, que vai de 1814 a 1850. A análise de manuais fotoquímicos oitocentista e das cartas trocadas por Niépce e Daguerre é uma prova disso. A heliografia e a daguerreotipia, entendidas como dispositivos so ciais, disputaram, a partir de suas substâncias fotossensíveis, um espaço de construção da verdade sobre um tempo-técnico de captação de imagem. Esta pesquisa partiu do princípio de que tal temporalidade ligada à estética fotográfica não é neutra à medida que se relaciona com modalizações histórico-temporais que emergem no campo do fotossensível. Pensamentos e práticas setecentistas, através de um tempo distenso, influenciaram as impressões das imagens de Niépce, cujas cópias solares advinham de uma intimidade com o mundo vital formado na interface de uma fisiologia da vida e uma química pré-moderna dos reinos naturais. Já as práticas de Daguerre se desenvolveram a partir de um tempo célere moderno. As impressões que resultam na imagem sobre a prata espelhada, banhada com iodo, bromo e cloro retomam fortemente os primeiros movimentos da química teórica cuja identidade encontrava-se atrelada ao inorgânico das sínteses laboratoriais. Essa disposição dicotômica dos saberes mostra que, na passagem do século XVIII para o XIX, uma série de conceitos que se davam a uma razão mais utilitarista não havia ainda atingido seu ideal de cientificidade, sendo perpassada por toda uma tradição de saberes de um mundo natural e espiritual. As experiências de Niépce emergem desse momento no qual a alquimia já não reinava e ainda se estava longe da figura do químico especializado. Neste contexto, Niépce ocupou um lugar de resistência aos saberes modernos. Tal fato implica uma revisão da afirmativa, tradicionalmente disposta nas histórias da fotografia, de que entre a duração da captação de imagem niépciana e o imperativo de uma aceleração temporal, representada pela captação de imagem daguerreana, havia um horizonte de expectativa que encaminharia ambas as experiências à premência temporal moderna. Esse dito não deve mais perdurar sob pena de se continuar mascarando, através de uma vontade de verdade desmedida, um espaço de resistência vicejante que fez surgir, a partir de uma lógica pré-moderna, um determinado sonho da imagem impressa por luz solar. / The passage from the 18th to 19th century is one of the most important to the understanding of what we are currently. Koselleck says that the period of time from 1750 to 1850 concerns an intermediate phase: we took no more the first steps towards an incipient modernity, and yet we did not reach the full rationalization announced by the „Lights‟. This conflict is reflected exemplary in the first decades of practice in printing images by sunlight, which goes from 1814 to 1850. The analysis of photochemical manuals of 18th century and the correspondence between Niépce and Daguerre prove this. Heliography and daguerreotype, considered social dispositive, disputed, through its photosensitive substances, a space on building the truth upon a technical time of image caption. This research assumed that such temporality, linked to photographic esthetic, isn‟t neutral, as it is related to historical and temporal modeling emerging in the photosensitive field. Thoughts and practices of 17th century, through a relaxed time, influenced the printing of Niépce images, whose sunlight copies derived from an intimacy with the vital world which is formed in the interface between a physiology of life and a pre-modern chemistry of natural realms. As to Daguerre practices, it were developed from a quick modern time. Printing resulting in the image on mirrored silver, iodine, bromine and chlorine plated, remake the first movements of theoretical chemistry, whose identity was tied to the inorganic of laboratory synthesis. This dichotomist disposition of knowledge shows that, in the passage from 18th to 19th century, a series of concepts which follows a more utilitarian reason, did not reached its ideal of science, being per passed by a whole tradition on knowledge of natural and spiritual realms. Niépce experiences come out of this moment where alchemy no more reign and we were far enough from the character of specialized chemist. In this context, Niépce occupied a place of resistance to modern knowledge. This fact implies a revision of the statement, traditionally disposed on photography history, which between the length of Niepce image caption and the imperative of a temporal acceleration, represented by Daguerre image caption, there was a horizon of expectations, which would lead both experiences to modern temporal urgency. This statement should no long last, or we will continue to hide, through a unmeasured truth wish, a luxuriant resistance space, that brought up, through a pre-modern logic, the dream of the image printed by sunlight.

Neste trabalho foram avaliadas as condições de processamento e caracterização da liga 66Co-28Cr-6Mo utilizada em implantes. Cada lingote foi produzido por meio de fusão a arco voltáico, sob atmosfera de argônio em um cadinho de cobre refrigerado à água. Os resultados foram comparados com aqueles de uma barra da liga 66Co-28Cr-6Mo comercial. A temperatura de forjamento a quente da liga é em torno de 1200º C, pois temperaturas menores levam a fraturas do material no decorrer do forjamento. Na análise química realizada na liga 66Co-28Cr-6Mo obteve-se uma concentração de 0,038%C, ou seja, esta concentração encontrada nos lingotes da liga 66Co-28Cr-6Mo produzida estão dentro das especificações da norma ASTM F1537 para a liga com baixo teor de carbono (0,14%C). Os lingotes apresentaram uma microestrutura policristalina, com presença de defeitos volumétricos (poros) possívelmente advindos do processo de solidificação. Foram realizados ensaios de oxidação nas temperaturas de 1200 oC, 1100 oC, 1000 oC e 900 oC por cerca de 30 minutos para avaliar o grau de oxidação da liga de 66Co-28Cr-6Mo em elevadas temperaturas, pois a conformação mecânica da liga é realizada a quente conforme descrito na norma ASTM F1537. O limite de escoamento à tração da liga 66Co-28Cr-6Mo na condição bruta é em média de 750 MPa e o módulo de elasticidade da mesma liga é, aproximadamente de 158 GPa. Notou-se na liga 66Co-28Cr-6Mo comercial uma microestrutura com grãos refinados, proveniente do processo de forjamento a quente. Além disso, observa-se a presença de maclas, porém não se pode afirmar se este defeito é devido à deformação plástica ou tratamento térmico. O limite de escoamento à tração da liga 66Co-28Cr-6Mo comercial foi de 975 MPa e módulo de elasticidade é, de aproximadamente de 203 GPa. A densidade de corrente de corrosão das ligas 66Co-28Cr-6Mo produzida e comercial são respectivamente 1,9x10-7 e 1,5x10-7 Acm-2. Estes valores indicam uma alta resistência à corrosão de ambas as ligas em solução de Ringer. As amostras das ligas 66Co-28Cr-6Mo comercial e produzida apresentaram uma curva de viabilidade celular acima da linha do índice de citotoxicidade (IC50%) = 50%, ou seja, as ligas são consideradas não tóxica. / In this study we evaluated the processing conditions and characterization alloy 28%Cr 66%Co-6%Mo used in implants. Each ingot was produced by through arc melting arcing under argon atmosphere in a water-cooled copper crucible. The results were compared with those of a commercial bar 66Co-28Cr-6Mo alloy. The temperature of hot forging 66Co-28Cr-6Mo alloy should be around 1200 º C because lower temperatures lead to fracture of the material during forging. In the chemical analysis performed on the alloy 66Co-28Cr-6Mo obtained a concentration 0,038 %C. Indeed the alloy 66Co-28Cr-6Mo produced are within the specifications of ASTM F1537 for the alloy with low carbon (0.14% C). The ingots had a polycrystalline microstructure with the presence of volumetric defects (pores) possibly arised from the solidification process. Oxidation tests were carried out at temperatures of 1200 oC, 1100 oC 1000 oC and 900 oC for about 30 minutes to evaluate the degree of oxidation of 66Co-28Cr -6Mo alloy at high temperatures because of the mechanical forming league will be held hot. The tensile yield strength of the 66Co-28Cre-6Mo alloy is provided and gross average of 750 MPa and elasticity of the same alloy is approximately 158 GPa. It was noted in the 66Co-28Cr-6Mo alloy commercial grain microstructure with a refined, from the hot forging process. Moreover, observed the presence of twinned, but one cannot say whether this defect is due to plastic deformation or heat treatment. The tensile yield strength of the 66%Co-28%Cr-6%Mo alloy trade was 975 MPa and modulus of elasticity is of approximately 203 GPa. The corrosion current density of the 66Co-28Cr-6Mo alloys and commercial produced are respectively 1,9.10-7 and 1,5.10-7 Acm-2. These values indicate a high corrosion resistence of both alloys in Ringer\'s solution. Samples of the commercial and produced 66Co-28Cr-6Mo alloys a curve above the cell viability index of citotoxicity (IC50%) = 50% the alloys are considered non-toxic.