Es geht nicht ohne und nicht mit dem Andern

Der Begriff Selbstentfremdung erscheint paradox: Gerade das Ureigenste tritt als fremd auf, während zugleich die Fremdheit einen Ort des Eigenen zu brauchen scheint, von dem aus sie konstatiert werden kann. Die Klärung des Begriffs kann sich folglich nicht darin erschöpfen das Individuum in jeder Hinsicht als entfremdetes, als bestimmt durch die Ideologie, den Anderen, die Macht der Sprache etc. auszuweisen, während zugleich kein Aspekt des Individuums als sein Wesenskern vom Fremdeinfluss isoliert werden könnte. Im Durchgang durch die Lacan'sche Theorie erweist sich die Selbstentfremdung nicht als Verhältnis zwischen „wahrer Natur“ und konstruiertem Selbst, sondern als die Dezentrierung des Subjekts, als seine Spaltung in zwei unvereinbare Seiten. Im irreduziblen Abstand beider Seiten liegt die Fremdheit im Selbst. Weder die unbewusste Seite des Begehrens und des Traumas, noch die des Ichs ist der Sitz der Subjektivität. Beide sind aus Sprache gemacht, aus dem Anderen. Die Notwendigkeit der Spaltung und des Ausschlusses verweist aber darauf, dass es eine Konfrontation gab. Das Subjekt geht nicht in einer geraden Linie aus dem Anderen als sein Effekt und Produkt hervor. Die Struktur des einzelnen Subjekts trägt die Spur der Unterwerfung durch den Anderen und weist deshalb jenseits des Anderen. Dieses Jenseits ist nicht verloren, sondern unauffindbar. Es bestätigt sich einzig im Akt der Verschiebung des Anderen und ist deshalb niemals mit und niemals ohne ihn. Als verschobene Ordnung existiert das Subjekt als Fremdes im Anderen

Asimetrično valjanje aluminijeve zlitine EN AW-5454

Rolling is as one of the most commonly used metal forming processes. In industrial practice, symmetric rolling technology is usually used. Nevertheless, it is possible to conduct an asymmetric rolling process. Introducing asymmetry in the rolling process is possible via different means. Asymmetry imparts changes in the technical and in the economical aspect of the rolling process. In the framework of this master thesis, the asymmetric rolling of EN AW-5454 aluminium alloy was investigated. For the planned rolling types, numerical simulations with similar conditions and entry rolling parameters were conducted. Symmetric and asymmetric rolling experiments were performed on a laboratory rolling mill and the exit obtained parameters were compared. The deformed workpieces were heat-treated and annealed. Different mechanical tests were performed on both the heat-treated and the deformed samples to find out the influence of asymmetric rolling on the resulting properties. Tensile, plastic strain ratio and hardness tests were performed respectively. Standard sample preparation procedures were applied to the samples subjects. Investigations of light optical and scanning electron metallography were carried out.Proces valjanja je eden najpogosteje uporabljenih postopkov preoblikovanja kovinskih materialov. V praksi se najpogosteje uporablja postopek simetričnega valjanja, lahko pa se uporablja tudi postopek asimetričnega valjanja. Asimetrični način valjanja se lahko izvede na več različnih načinov. Na proces valjanja ima asimetrija pozitiven vpliv tako v tehnološkem kot tudi ekonomskem smislu. V okviru magistrske naloge smo raziskovali asimetrično valjanje aluminijeve zlitine EN AW- 5454. Za predvidene načine valjanja smo pri podobnih pogojih in vhodnih parametrih izdelali simulacije valjanja. Na laboratorijskem valjalnem stroju smo izvedli simetrično kot tudi asimetrično valjanje in različne izhodne parametre valjanja primerjali med seboj. Na deformiranih vzorcih smo izvedli toplotno obdelavo. Vzorce smo žarili do mehkega stanja. Na deformiranih kot tudi na toplotno obdelanih vzorcih smo za ugotovitev vpliva asimetričnega valjanja na mehanske lastnosti izvedli več različnih mehanskih preizkusov. Izvedli smo natezni preizkus, test plastične obremenitve in merjenje trdote. Spremembe mehanskih lastnosti smo analizirali s pomočjo metalografije, kjer smo uporabili optični mikroskop (LOM) in vrstični elektronski mikroskop (SEM)

Characterization of biodegradable alloys based on Fe-Mn synthesized by selective laser melting

Nepogrešljiva prisotnost kovinskih materialov v medicinskih aplikacijah je z najnovejšimi izzivi in trendi prehoda iz stalnih na začasne implantante bila razširjena tudi na raziskovanje biorazgradljivih kovinskih materialov. Glede na pomanjkljivosti prepočasne razgradnje zlitin na osnovi Fe, se dodatek Mn ter posledično zlitine iz sistema Fe-Mn obravnavajo kot ene najbolj perspektivnih za izdelavo in kasnejšo uporabo v želenih aplikacijah za medicinske namene. Pri ustvarjanju in razvoju novih zlitin in izdelkov iz navedenega binarnega sistema, ki bi izkazovali za telo neškodljivo in povečano stopnjo razgradljivosti, smo glede na ustvarjalne prednosti dodajalnih tehnologij izbrali selektivno lasersko taljenje. Z raziskavami smo v prvi vrsti dokazali razlike med uporabo mehansko mešanih elementarnih kovinskih prahov in predhodno izdelanimi zlitinskimi kovinskimi prahovi. Hitrost napredovanja korozije kot tudi raztapljanje izdelkov iz primerjanih kovinskih prahov izdelanih s selektivnim laserskim taljenjem v različnih medijih lahko ocenimo kot povsem primerljivo. Z omogočenim načinom spreminjanja obratovalnih parametrov (moč laserja in hitrost vrstičenja) in obsežno karakterizacijo materiala smo izdelali procesna okna, ki so nam služile za ugotavljanje vpliva in optimizacijo parametrov, kar je vodilo v izbiro najugodnejših obratovalnih parametrov za povečanje reakcijske površine in posledičnega hitrejšega napredovanja korozije. Iz potrebe po prekrivanju premera laserskega snopa in medlaserske razdalje smo izpeljali novo enačbo za izračun gostote vnesene energije. Za podrobno analizo in ugotovitev vpliva procesnih parametrov smo primerjali tudi vzorce izdelane z enako vneseno gostoto energije vendar uporabljenimi različnimi vrednostmi moči laserja in hitrosti vrstičenja. Kljub opaženemu splošnemu upočasnjevanju hitrosti napredovanja korozije ob dodatku Ag nam je s Fe-Mn-Ag zlitino in s skoraj polovično vrednostjo ustvarjene poroznosti uspelo izdelati material s hitrostjo korozije kar 1775,22 µm/leto.With the current trends to make a transition from permanent to temporary medical implants, the indispensable presence of metallic materials in medicinal applications has been extended to the research of biodegradable metallic materials. Taking the disadvantages of slow decomposition of Fe-based alloys into account, the addition of Mn and consequently alloys from the Fe-Mn system is considered one of the most promising for manufacturing and subsequent use in applications for medical purposes. In the creation and development of new alloys and products from the above binary system, which would show an increased degree of degradability, we have chosen a selective laser melting due to the creative advantages of additive manufacturing. Through our research, we firstly demonstrated the differences between the use of mechanically mixed elemental metal powders and prefabricated alloy metal powders systematically. The rate of corrosion progression as well as the dissolution of products from the compared metal powders made by selective laser melting in different media can be assessed as entirely comparable. With the ability of modifying the operating parameters (laser power and scanning speed), we created process maps at different levels of material characterization, which served us to determine the impact and optimize the parameters. It all led to the selection of the most favorable operating parameters to increase the reaction surface and consequently to a faster progress in corrosion. From the need to overlap the laser diameter and the hatch distance, we have derived a new equation to calculate the input energy density. For a more detailed analysis, and to determine the impact of process parameters, we have also compared the samples manufactured with the same input energy density but using different laser power and scanning speed combinations. Despite the general inhibition of the corrosion rate with the addition of Ag, we have managed to produce a material with as much as 1775.22 μm /year with FeMnAg alloy and almost half the value of the generated porosity

Cold Rolling Technology Optimization for EN AW 4343/3003/4343 Cladded Aluminum Alloys and Influence of Parameters on Microstructure, Mechanical Properties and Sustainable Recyclability

The present study investigates the accumulative roll bonding process applied to the EN AW 3003 aluminum alloy, serving as a composite material on both sides and consisting of the EN AW 4343 aluminum alloy. For the characterization of the optical microscopy, corrosion tests with saltwater acetic acid and mechanical properties before and after the braze test were employed. The numerical simulations accurately predicted the industrial cold rolling values for the rolling force and surface temperature. The most comprehensive understanding of the cold rolling parameters for both side-cladded materials was achieved by combining predictions for cladded and uncladded materials. The thickness of the cladded layer presented as a percentage after roll bonding was 18.7%. During the cold rolling and annealing, the cladded thickness was increased to 24.7% of the final 0.3 mm of the total cold-rolled product thickness. According to the performed braze test for final thickness, the ultimate tensile strength and yield strength were decreased, and the elongation increased to 18.1%. In addition to the described changes in mechanical properties, the material’s anisotropy improved from 5.4% in the cold-rolled condition to 2.0% after the braze test. After multiple re-meltings of the cladded material, the analyzed chemical compositions allow for recycling and reuse as different 4xxx, 5xxx, and 6xxx alloys

Influence of the Energy Density for Selective Laser Melting on the Microstructure and Mechanical Properties of Stainless Steel

We have investigated the impact of the process parameters for the selective laser melting (SLM) of the stainless steel AISI 316L on its microstructure and mechanical properties. Properly selected SLM process parameters produce tailored material properties, by varying the laser’s power, scanning speed and beam diameter. We produced and systematically studied a matrix of samples with different porosities, microstructures, textures and mechanical properties. We identified a combination of process parameters that resulted in materials with tensile strengths up to 711 MPa, yield strengths up to 604 MPa and an elongation up to 31%, while the highest achieved hardness was 227 HV10. The correlation between the average single-cell diameter in the hierarchical structure and the laser’s input energy is systematically studied, discussed and explained. The same energy density with different SLM process parameters result in different material properties. The higher energy density of the SLM produces larger cellular structures and crystal grains. A different energy density produces different textures with only one predominant texture component, which was revealed by electron-backscatter diffraction. Furthermore, three possible explanations for the origin of the dislocations are proposed

Metal Artefacts and Remains of Armour from Kozlov Rob Castle: Metallurgical Analyses as a Tool for Identification and Interpretation of Fragmentary Archaeological Finds

The castle on Kozlov Rob above Tolmin is one of the most important historical sites in western Slovenia. Over the years, large quantities of finds dating from the late medieval and early modern periods have been recovered from the castle ruins in the process of archaeological investigations and construction works. Many of the recovered iron artefacts are extremely difficult to identify due to their fragmentary state. This paper presents the study of four relatively recently discovered artefacts. The available evidence suggests that at least one of them belongs to a helmet, while another has been identified as the remains of a lock. The artefacts were analysed with X-ray radiography and X-ray diffraction. Additionally, samples were taken for microhardness Vickers measurements and metallographic analysis with a light microscope and a scanning electron microscope. Additional microchemical and structural phase analysis were done with the electron microscope. The aim of archaeometallurgical analyses is to contribute to a more precise interpretation and add a new dimension to our knowledge of the castle site at Kozlov Rob

Thermodynamic behavior of Fe-Mn and Fe-Mn-Ag powder mixtures during selective laser melting

Additive manufacturing is a form of powder metallurgy, which means the properties of the initial metal powders (chemical composition, powder morphology and size) impact the final properties of the resulting parts. A complete characterization, including thermodynamic effects and the behavior of the metal powders at elevated temperatures, is crucial when planning the manufacturing process. The analysis of the Fe-Mn and Fe-Mn-Ag powder mixtures, made from pure elemental powders, shows a high susceptibility to sintering in the temperature interval from 700 to 1000 °C. Here, numerous changes to the manganese oxides and the αMn to βMn transformation occurred. The problems of mechanically mixed powders, when using selective laser melting, were highlighted by the low flowability, which led to a less controllable process, an uncontrolled arrangement of the powder and a large percentage of burnt manganese. All this was determined from the altered chemical compositions of the produced parts. The impact of the increased manganese content on the decreased probability of the transformation from γ-austenite to ε-martensite was confirmed. The ε-martensite in the microstructure increased the hardness of the material, but at the same time, its magnetic properties reduce the usefulness for medical applications. However, the produced parts had comparable elongations to human bone

Asymmetric rolling process

Asymmetric rolling is a novel technique used to control both the texture and the grain refinement of metallic materials. The aim of asymmetric rolling is to apply a large shear strain uniformly through the thickness of the plate, by maintaining a high degree of friction between the sheet and the rolls. It can be used to improve the formability of material. One of the advantages of asymmetrical rolling is that the rolling force and torque can be decreased. The methods used for the asymmetric rolling are single roll drive, different work roll speeds, different work roll diameters or different lubricated work roll surfaces

Microstructure and texture evolution with relation to mechanical properties of compared symmetrically and asymmetrically cold rolled aluminum alloy

The impact of asymmetric cold rolling was quantitatively assessed for an industrial aluminum alloy AA 5454. The asymmetric rolling resulted in lower rolling forces and higher strains compared to conventional symmetric rolling. In order to demonstrate the positive effect on the mechanical properties with asymmetric rolling, tensile tests, plastic-strain-ratio tests and hardness measurements were conducted. The improvements to the microstructure and the texture were observed with a light and scanning electron microscopethe latter making use of electron-backscatter diffraction. The result of the asymmetric rolling was a much lower planar anisotropy and a more homogeneous metal sheet with finer grains after annealing to the soft condition. The increased isotropy of the deformed and annealed aluminum sheet is a product of the texture heterogeneity and reduced volume fractions of separate texture components