Thesis: Sc. D., Massachusetts Institute of Technology, Department of Metallurgy, 1947 / Vita. / Includes bibliographical references (leaves 183-184). / by Recep Ali Safoglu. / Sc. D. / Sc. D. Massachusetts Institute of Technology, Department of Metallurgy

Выпускная квалификационная работа (магистерская диссертация) посвящена исследованию налогового планирования и налоговой оптимизации на предприятии. Предметом исследования выступают совокупность экономических отношений, направленных на деятельность предприятия по налоговому планированию и налоговой оптимизации. Основной целью магистерской диссертации является разработка теоретических положений по налоговому планированию и практических рекомендаций по проблеме налогового планирования и налоговой оптимизации. / Tax planning for many became one more source of financing and also a factor, increasing competitiveness of the produced goods and services. Heads are interested more in a tax planning, in tax minimization by lawful or illegal methods, as economy on tax payments in fact it is a reserve for increase in profit and consequently, increases in dividends. In these conditions, the importance tax planning increases every day.

Pulvermetallurgi är en tillverkningsteknik för en stor mängd maskinkomponenter såsom kugghjul, lager och filter. Tillverkningen sker genom sammanpressning och upphettning, eller sintring, av ett fint metallpulver för att på så sätt direkt skapa komponenter med önskad form, istället för att behöva skära bort delar av detaljen för att det ska erhålla den önskade formen. Detta är särskilt fördelaktigt vid kugghjulstillverkning, på grund av deras komplexa former. Tekniken är även ekonomiskt fördelaktig eftersom den knappt producerar något spillmaterial alls i jämförelse med alternativa tillverkningstekniker. Syftet med denna studie var att undersöka huruvida pulvermetallurgi är lämplig som tillverkningsmetod för kugghjul som ska användas i lastbilars växellådor, en applikation som kännetecknas av väldigt höga belastningar och driftsäkerhetskrav. Undersökningen genomfördes genom studie av tre fallstudier och en intervju. Resultatet löd att pulvermetallurgi har svårt att mäta sig med de alternativa tillverkningsmetoder som finns för denna typ av kugghjul när det gäller uppnådd komponentlivslängd, förmodligen på grund av svårigheter med att minimera porer. Dock kan en omställning till kugghjul tillverkade enligt pulvermetallurgiskt vis fortfarande vara ekonomiskt försvarbart tack vare teknikens kostnadsfördelar som erhålls ur en lägre grad av materialförbrukning. Ett företags val av tillverkningsteknik bör baseras på vilken teknik som kan skapa den bästa och långsiktigt hållbaraste ekonomiska utvecklingen. / Powder metallurgy is a manufacturing method for a vast amount of machine components, including gears, bearings and filters. The production is carried out through compression and heating, or sintering, of a fine metal powder, in order to directly produce components with the wanted geometrical dimensions instead of having to shape the components through cutting or machining procedures. This is especially advantageous when producing gears, because of their complex shapes. The technique is also economically advantageous since it barely produces any spill material at all incomparison to alternative manufacturing techniques. The purpose of this study was to examine whether powder metallurgy could be an appropriate manufacturing method for gears used in the transmission of a truck, an application that is characterized by high loads and strong demands on dependability of the gears. The investigation was carried out through analyzing three case studies and through one interview. The result stated that powder metallurgy has difficulties to compete with the other options of manufacturing methods that exists for this application when it comes to achievable component lifetime, which probably is a consequence of the difficulties in minimizing pores. Despite this may a switch to powder metallurgically manufactured gears still be economically sound thanks to the technology’s cost advantages due to the higher raw material utilization. A company’s choice of manufacturing technology should be based on which technology that can create the best and most long‐term sustainable economic development.

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In this work, the metal and slag phase mixing in three steps of a ladle refining operation of steel melts and for an oxygen balance during cooling of cast iron melts have been studied at two Swedish steel plants and at two Swedish cast iron foundries, respectively. In order to predict the oxygen activity in the steel bulk in equilibrium with the top slag as well as in metal droplets in the top slag in equilibrium with the top slag, three slag models were used. In addition, the assumptions of a sulphur-oxygen equilibrium between steel and slag and the dilute solution model for the liquid steel phase were utilized in the calculations. Measured oxygen activities in steel bulk, which varied between 3.5-6 ppm, were compared to predicted oxygen activities. The differences between the predicted and measured oxygen activities were found to be significant (0-500%) and the reasons for the differences are discussed in the thesis. Slag samples have been evaluated to determine the distribution of the metal droplets. The results show that the relatively largest numbers of metal droplets are present in the slag samples taken before vacuum degassing. Also, the projected interfacial area between steel bulk and top slag has been compared to the interfacial area between the metal droplets and slag. The results show that the droplet-slag interfacial area is 3 to 14 times larger than the flat projected interfacial area between the steel and top slag. Furthermore, the effect of the reactions between top slag and steel and the slag viscosity on the metal droplet formation is discussed. The results show significant differences between the steel bulk and steel droplet compositions and the reasons for the differences are discussed in the thesis. The oxygen activity in different cast irons was studied. Plant trials were performed at three occasions for lamellar, compacted and nodular iron melts. The results show that at temperatures close to the liquidus temperature the oxygen activities were 0.03-0.1 ppm for LGI, around 0.02 ppm for CGI, and 0.001ppm for SGI. In addition, it was found that as the oxygen activities increased with time after an Mg treatment, the ability to form a compact graphite or a nodular graphite in Mg-treated iron melts was decreased. Also, extrapolated oxygen activity differences up to 0.07 ppm were found for different hypoeutectic iron compositions for lamellar graphite iron at the liquidus temperature. Overall, the observed differences in the dissolved oxygen levels were believed to influence how graphite particles are incorporated into the austenite matrix and how the graphite morphology will be in the cast product. / <p>QC 20160518</p>

Particulate reinforced Al alloy composites (AlMCs) are recognized as important structural materials due to their lightweight, high modulus and strength and high wear resistance. In order to understand the effect of matrix, reinforcement and secondary processing techniques on the microstructure development and mechanical properties of AlMCs produced by powder metallurgy routes, Al alloy composites reinforced with three types of reinforcements by different secondary processing techniques have been produced and examined. Fabrication of Al or 6061Al alloy based composites reinforced with nano-sized SiC particles (~500nm), micro-sized (<25µm) quasicrystalline alloy particles (hereinafter referred to as “NQX”) and micro-sized Nb particles (~130µm) has been carried out by powder metallurgy routes followed by extrusion or cold rolling. After extrusion, a homogeneous distribution of secondary particles has been obtained with rare interfacial reaction products. The 6061Al/SiC composites exhibit superior mechanical properties than either monolithic alloys or composites reinforced with micro-sized particles with retained ductility while the 6061Al/NQX and 6061Al/Nb composites show limited improvement in tensile strength mainly due to their reinforcement size and poor interfacial bonding. After cold rolling, the evolution in microstructure, texture and strength has been analysed. A typical near β fibre texture with highest intensities near Copper and Brass orientations has been developed for 6061Al/NQX and 6061Al/Nb composites. For 6061Al/SiC composites, a randomized texture with very small grains has achieved due to the presence of the non-deformable SiC particles. Mechanical property tests including microhardness, three-point bending tests and tensile tests have been carried out on cold rolled samples and the results exhibit some level of improvement when compared with as-extruded samples due to work hardening. Finally, the work moves on to the general discussion based on the previous result chapters. The microstructural development related to reinforcement, matrix and interfacial areas during extrusion and cold rolling has been summarised and the correlation between microstructure and mechanical properties has been discussed. The thesis provides a thorough understanding of AlMCs produced by powder metallurgy routes in terms of matrix, reinforcement and processing techniques. It can provide reference to the future development of AlMCs for high strength applications.

This study was an evaluation of thermite rail welding with the goal of the development of welds with improved mechanical properties. The first part of the study involved an in-depth evaluation of 14 thermite rail welds produced by the Department of Transportation using current production practices. These welds were produced using CrMo, CrV and Cr alloy rails, AREA CC rails (i.e., standard rails) and head-hardened rails which were welded with weld metal produced by the aluminothermic reaction of "standard" and "alloy" thermite charges. Temperature at various locations was measured during welding for both the rails and the weld metal. After welding, mechanical properties, macro- and microstructure, inclusion levels and residual stresses induced by the welding operation were all determined. Low impact properties and ductility (2-6 percent reduction in area) were observed in the thermite rail weld metal. These low properties were attributed to microstructure and, to a lesser extent, inclusion content. In order to improve the process by reducing the inclusion content, attempts were made to filter the molten thermite steel by passing it through zirconia/mullite filters. This was included in the second part of the study in which 9 plate welds we made using "standard" thermite charges. Filtering, at best, was only partly successful. However, it was observed that a 30 percent increase in yield strength and hardness was achieved in weld metal containing approximately 0.55 percent carbon and 0.06 percent vanadium. Normalization of the plate welds resulted in a significant improvement in the tensile ductility of as-cast weld metal. Weld metal of 0.55 percent carbon and 0.06 percent vanadium had ductilities in the range of 10-20 percent when the cooling rate exceeded 37 K(DEGREES)/min. through the transformation range. At cooling rates of four times this level, tensile properties equivalent to those of the "alloy" weld metal were obtained along with the enhanced tensile ductility. It was concluded that it is possible to produce a thermite weld with both improved strength and ductility by the judicious control of composition, the addition of microalloying elements and the application of an appropriate post-weld heat treatment, such as normalization.