TY - PAT A1 - Michailov, Vesselin A1 - Ossenbrink, Ralf A1 - Schleuß, Leander A1 - Springer, Katrin A1 - Zoeke, Jörg T1 - Strukturierte Tailored Blanks T1 - Structured tailored blank useful as a semi-finished product or a finished product, which is used as a component, preferably wall element, floor element, ceiling element and/or element of chassis of vehicle, comprises at least two sheets N2 - Die Erfindung betrifft ein strukturiertes Tailored Blank, umfassend mindestens zwei Fügepartner, wobei mindestens ein Fügepartner ein strukturierter Fügepartner ist und wobei der strukturierte Fügepartner regelmäßig angeordnete Versteifungselemente umfasst und wobei der strukturierte Fügepartner an mindestens einen weiteren Fügepartner gefügt ist. N2 - Structured tailored blank comprises at least two sheets. At least one sheet is at least one structured sheet. The structured sheet comprises regularly arranged stiffening elements of honeycomb shapes without planar sections. The stiffening elements are separated by bars. The structured sheet is joined to at least one additional sheet, and both the sheets are not similar. An independent claim is also included for producing the structured tailored blank, comprising the providing first structured sheet, providing at least one additional sheet, which is not similar to the first sheet, and joining the first sheet with at least one additional sheet. Y1 - 2014 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102013101171A1 ER - TY - PAT A1 - Schleuß, Leander A1 - Seidlitz, Holger A1 - Michailov, Vesselin T1 - Neue Fügetechnologie für Mischverbindungen Y1 - 2017 UR - https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102015118058A1 N1 - Offenlegungsschrift ER - TY - GEN A1 - Kondrat’ev, Sergey A1 - Morozova, Iuliia A1 - Golubev, Iurii A1 - Hantelmann, Cord A1 - Naumov, Alexander A1 - Michailov, Vesselin T1 - Microstructure and Mechanical Properties of Welds of Al – Mg – Si Alloys After Different Modes of Impulse Friction Stir Welding T2 - Metal Science and Heat Treatment N2 - Welded joints of aluminum alloy 6082-T6 formed by the method of impulse friction stir welding are studied. The effect of the power and frequency of the pulses on the microstructure and mechanical properties of the welded joints is determined. Application of an additional pulse during the welding affects the surface quality and the shape of the weld, the distribution of the oxide layer and of particles of the hardening phase, and the grain size in the zone of dynamic recrystallization. KW - impulse friction stir welding KW - power and frequency of pulses KW - microstructure KW - mechanical properties KW - Al – Mg – Si alloy Y1 - 2018 UR - https://link.springer.com/article/10.1007%2Fs11041-018-0213-6 U6 - https://doi.org/10.1007/s11041-018-0213-6 SN - 0026-0673 VL - 59 IS - 11-12 SP - 697 EP - 702 ER - TY - GEN A1 - Michailov, Vesselin A1 - Fritzsche, Sebastian A1 - Hantelmann, Cord A1 - Ossenbrink, Ralf T1 - Aluminium foam sandwiches for lightweight structures T2 - Metal Science and Heat Treatment N2 - The properties of sandwiches with aluminum foam and the special features of their use in lightweight welded structures are determined. The weldability of such sandwiches in foamed and non-foamed conditions is analyzed under friction stir welding, laser beam welding and short arc welding in protective gas. The process and mechanical properties of the welds are studied. The results are generalized in a catalog that may be useful for materials scientists and designers. KW - aluminum KW - aluminum foam KW - welded structures KW - composite materials KW - structure KW - mechanical properties Y1 - 2018 U6 - https://doi.org/10.1007/s11041-018-0238-x SN - 1573-8973 VL - 60 IS - 1-2 SP - 44 EP - 49 ER - TY - GEN A1 - Wasilewski, Eric A1 - Wolf, Matthias A1 - Zhang, Wei A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Cu/LaCrO₃ joining by local melt infiltration through laser cladding T2 - Journal of the American Ceramic Society N2 - Direct bonding of copper and porous LaCrO₃ without an extra filler interlayer was successfully completed using local and fast Cu‐infiltration through laser cladding. This significantly reduced the susceptibility of the ceramic to cracking. A high‐speed camera investigation into the wetting and infiltration behavior of a Cu‐melt into LaCrO₃ with a porosity of ~63 vol% was performed. By adjusting the focal distance with a constant laser power of 300 W, the Cu‐melt was rapidly infiltrated into the ceramic preform in 10 seconds. This was completed under atmospheric air conditions, without added inert gas. The joining process developed can be used to fabricate ceramic/metal joints with targeted (micro‐) structure properties by adjusting the infiltrated melt and the infiltration depth, which would be suitable for many applications, such as multifunctional devices, solid oxide fuel cells or heating elements. Y1 - 2018 U6 - https://doi.org/10.1111/jace.15767 SN - 1551-2916 SN - 0002-7820 VL - 101 IS - 10 SP - 4472 EP - 4472 ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Panchenko, Oleg V. A1 - Michailov, Vesselin T1 - Comparative analysis of non-uniformity of mechanical properties of welded joints of Al - Mg - Si alloys in friction stir welding and laser welding T2 - Metal Science and Heat Treatment N2 - The properties of the welded joints of 6082-T6 alloy produced by friction stir welding (FSW) and laser welding(LW) were studied. The maximum temperature and microhardness fields in the friction stir-welded joints were shown to be asymmetrical. The concentrated energy input during laser welding yields a narrow heat-affected zone (HAZ) with sharp changes in mechanical properties. The strength of the FSW joint constitutes 72% and that of the LWjoint—67% of the base metal strength. In case of LW, the minimum hardness of the joint corresponds to the metal of the welded joint, while in case of FSW, it corresponds to the heat-affected zone. At the same maximum heating temperature, the hardness of the heat-affected zone of the friction stir-welded joint is lower compared to laser welding due to substantially lower rates of heating and cooling. KW - friction stir welding KW - laser welding KW - Al – Mg – Si alloy KW - temperature field KW - welded joint KW - microstructure KW - mechanical properties KW - non-uniformity Y1 - 2018 UR - https://link.springer.com/article/10.1007/s11041-018-0289-z U6 - https://doi.org/10.1007/s11041-018-0289-z SN - 0026-0673 VL - 60 SP - 393 EP - 398 ER - TY - CHAP A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin ED - Seefeldt, Marc T1 - Strength Calculation of Stiffened Structures Taking Into Consideration Realistic Weld Imperfections T2 - European Conference on Residual Stresses 2018, ECRS-10, Leuven, Belgium, 11-14th September, 2018 N2 - The topic of this article is the application of an analytical numerical hybrid model for a realistic prediction of imperfections induced by welds. At the beginning, the analytical model, its physical basis as well as the physical interrelationships are explained. This is followed by the explanation of the coupling procedure between the analytical model and the numerical calculation. Afterwards, the coupled hybrid model is applied on the investigated stiffened curved structure for the determination of the weld imperfections. An ultimate load analysis gives information about the load carrying behavior under axial loading. The results are compared against the traditional approach using eigenmode-based imperfections. The comparison underlines the potential additional utilization of load bearing capacity by this new approach. Y1 - 2018 SN - 978-1-945291-88-3 SN - 978-1-945291-89-0 U6 - https://doi.org/10.21741/9781945291890-39 SP - 245 EP - 250 PB - Materials Research Forum LLC CY - Millersville, PA ER - TY - GEN A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Traglastberechnung versteifter Platten und Schalen unter Berücksichtigung realer Schweißimperfektionen T2 - Bauingenieur N2 - Imperfektionen, die bei Traglastberechnungen Berücksichtigung finden müssen, haben ihre Ursachen in Herstellungs- und Fertigungstoleranzen oder werden durch das Schweißen und den damit zumeist einhergehenden Nachbehandlungen in den Bauteilen hervorgerufen. Durch die Wärmewirkung des Schweißens entstehen sowohl sehr große Verformungen als auch signifikante Zug und Druckspannungen. Der strukturelle und geometrische Imperfektionsgrad wird somit maßgeblich von der Anzahl und der Lage der Schweißnähte sowie den Schweißparametern bestimmt. Für die Berücksichtigung in Traglastberechnungen ist ein physikalisch fundiertes Modell erforderlich, welches die Schweißimperfektionen schnell und präzise berechnet. Das gekoppelte analytisch numerische Hybridmodell erfüllt diese Kriterien. Die mathematischen Grundlagen des analytischen Modells sowie die Kopplung mit der numerischen Finite-Elemente-Berechnung werden eingangs vorgestellt und die Anwendung zur Berechnung von Verzügen an einer Schiffsektion demonstriert. Darauffolgend wird das Hybridmodell an einer eben und einer gekrümmten versteiften Platte zur Berechnung der Schweißimperfektionen angewendet. Anschließende Traglastberechnungen sowie der Vergleich mit den Ergebnissen unter der Annahme einer geometrischen Ersatzimperfektion in Form des kritischsten Eigenwerts gibt Auskunft darüber, welches Potenzial die realitätsnahe direkte Berücksichtigung von Schweißimperfektionen birgt. Y1 - 2018 SN - 0005-6650 VL - 93 IS - 10 SP - 403 EP - 411 ER - TY - CHAP A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - The Influence of Geometrical and Welding Imperfections on the Strength of Stiffened Structures T2 - High Performance Steel Structures Research Council (HPSSRC), Delft, Netherlands, 2018 N2 - The strength calculation of stiffened plates and shells via finite element simulation has been part of the state of the art for a long time. Geometrical nonlinearities as well as the nonlinear material behavior are considered within the calculation. To simplify, both types of imperfections, geometrical and structural ones, are mostly combined in these strength calculations being considered as equivalent geometrical imperfections. Values for standard cases are included in EN 1993-1-5 in case of plated structures or 1-6 in case of shells. A second possibility is the separate definition of fabrication tolerances and residual stresses, as far as they are known. With increasing complexity of the structure, less information are however available on geometrical and particularly structural imperfections. Nevertheless, by means of a more realistic consideration of these values, the actual ultimate load can be determined significantly more exactly and the performance of high performance steel structures is increased. In the investigated cases, deformations and stresses arise mainly due to welding. Therefore, the topic of this article is the application of an analytical numerical hybrid model for predicting imperfections induced by welds. This is presented on an example of a stiffened steel structure and a subsequent ultimate load calculation. At the beginning the analytical model, its physical basis as well as the physical interrelationships are introduced and explained. This is followed by the explanation of the coupling procedure between the analytical model and the numerical calculation for the calculation of weld-induced deformations and residual stresses. The significance of the hybrid model is proven by means of a few sample applications. For a realistic determination of the weld imperfections in the investigated stiffened structure, the coupled hybrid model is used afterwards. An ultimate load analysis gives information about the load carrying behavior under axial loading. The results are compared with the results of an ultimate load analysis from a literature example assuming different eigenvalues with different scaling. The results underline the potential additional utilization of load bearing capacity by this new approach. KW - Welding KW - Stresses KW - Strains KW - Imperfections KW - Stiffened Structures KW - Distortions Y1 - 2018 UR - https://www-docs.b-tu.de/fg-stahlbau/public/Fachgebiet_Stahlbau/publikationen/Workshop_Proceedings_of_HPSSRC-updated_cs.pdf SP - 191 EP - 201 ER - TY - CHAP A1 - Ginzburg, Svetlana A1 - Morozova, Iuliia A1 - Kloshek, Alexander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Schweißen von Stahl mit Nanopartikel modifizierten Fülldrähten - Schweißnahtgefüge und -eigenschaften T2 - DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018 N2 - Analyse des Schweißnahtgefüges und -eigenschaften beim Schweißen von Stahl mit Nanopartikel modifizierten Fülldrähten KW - Schweißen KW - Fülldraht KW - Nano KW - Nanotechnologie KW - Stahl KW - Gefüge Y1 - 2018 SN - 978-3-96144-036-8 SP - 40 EP - 46 PB - DVS Media GmbH CY - Düsseldorf ER - TY - CHAP A1 - Fritzsche, Sebastian A1 - Kloshek, Alexander A1 - Dietz, Eric A1 - Michailov, Vesselin A1 - Seidlitz, Holger A1 - Ossenbrink, Ralf T1 - SLM gefertigte Verbindungsknoten für Leichtbaurahmenelemente T2 - DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018 N2 - SLM gefertigte Verbindungsknoten für Leichtbaurahmenelemente KW - Selective Laser Melting KW - SLM KW - Leichtbau KW - 1.4404 KW - Topologieoptimierung KW - Schubfeld Y1 - 2018 SN - 978-3-96144-036-8 IS - 264 EP - 258 PB - DVS Media GmbH CY - Düsseldorf ER - TY - CHAP A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Unterstützung beim thermischen Richten von geschweißten Großstrukturen durch praktikable Computersimulationen T2 - DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vorträge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018 N2 - Unterstützung beim thermischen Richten von geschweißten Großstrukturen durch praktikable Computersimulationen KW - Thermisches Richten KW - Großstrukturen KW - Simulation KW - Umformen KW - Schiffbau KW - Richten Y1 - 2018 SN - 978-3-96144-036-8 SP - 364 EP - 369 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Bokuchava, Gizo A1 - Petrov, Peter A1 - Genchev, Gancho Vladimirov A1 - Michailov, Vesselin A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf T1 - Residual stress analysis in welded joints by neutron difffraction and comouter modeling T2 - Romanian Journal of Physics N2 - Numerical models for thermo-mechanical simulation of the welding residual stresses in laser beam and multi-pass arc welded joints are developed. The models describe the resulting microstructure as a function of the peak temperature, austenization time, cooling time and take into account the microstructure formed after single or multiple thermal cycles. The results of simulations are validated by neutron diffraction experiments performed on FSD diffractometer at the IBR-2 pulsed reactor in FLNP JINR (Dubna, Russia). The elaborated numerical models are in good agreement with obtained neutron diffraction data, which enable to study the influence of different conditions and process parameters on the distribution of residual welding stresses. KW - residual stress KW - neutron diffraction KW - computer modeling KW - welding Y1 - 2018 SN - 1221-146X VL - Vol. 63 IS - 7-8 ER - TY - GEN A1 - Zhang, Wei A1 - Evdokimov, Anton A1 - Schleuß, Leander A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Laser beam build-up welding of AlSi12-powder on AlSi1MgMn-alloy substrate T2 - Progress in Additive Manufacturing N2 - In the present work, laser beam build-up welding of AlSi12 alloy powder on AlSi1MgMn-alloy (EN AW-6082) substrate has been studied to determine the laser deposition strategy for fabrication of 3-D structure. First, the influence of laser power, scanning speed and powder feeding rate on the output parameters, such as clad geometry, dilution ratio, powder efficiency and porosity were analysed for deposition of a single track. Mathematical relationships were then established and the optimal parameters were identified by the desirability approach. Second, these optimal process parameters are furthermore adjusted to fabricate rectangular, cylindrical and complex combination volumes; different layer deposition strategies are used and evaluated. Finally, by using an adapted deposition strategy, one prototype consisted of different complexly shaped elements on one curved Al-alloy substrate without welding fusion defects was manufactured. The average tensile strength of deposited samples with four different layer deposition directions (vertical 0°/90°; horizontal 0°/90°; horizontal 0° and horizontal 90°) was measured, respectively, which are comparable strengths or higher than those of cast samples. The microstructure of the laser-deposited material is investigated using optical microscopy and scanning electron microscopy as well as microcomputed tomography. Microstructure and hardness of deposited multilayers exhibit inhomogeneous distributions, which vary with the deposit location KW - Laser beam build-up welding KW - Laser metal deposition KW - AlSi12 KW - Additive manufacturing KW - Build-up strategy Y1 - 2019 UR - https://doi.org/10.1007/s40964-018-0065-z SN - 2363-9512 VL - 4 IS - 2 SP - 117 EP - 129 ER - TY - GEN A1 - Ivanov, Sergey Y. A1 - Karkhin, Victor A. A1 - Michailov, Vesselin A1 - Martikainen, J. A1 - Hiltunen, E. T1 - Assessment of the Sensitivity of Welded Joints of Al –Mg – Si Alloys to Liquation Cracks Under Laser Welding T2 - Metal Science and Heat Treatment N2 - The microstructure and the distribution of chemical elements in laser-welded joints of Al – Mg – Si alloy 6005-T6 are studied. Segregations of chemical elements are detected over grain boundaries in the heat-affected zones of the welded joints. The joints fracture by the intergrain mechanism. A Gleeble 3800 device is used to determine the temperature dependences of the mechanical properties of the alloy with allowance for the special features of the welding cycle. Amethod for evaluating the sensitivity of welded joints of aluminum alloys to formation of liquation cracks with allowance for the local properties of the metal, the welding conditions, and the rigidity of the construction is suggested. KW - laser welding KW - Al – Mg – Si alloy KW - microstructure KW - microscopic chemical analysis KW - liquation cracks KW - stress-strain state Y1 - 2018 U6 - https://doi.org/10.1007/s11041-018-0225-2 SN - 0026-0673 VL - Vol. 59 IS - 11-12 SP - 773 EP - 778 ER - TY - GEN A1 - Bobrynina, E. V. A1 - Larionova, T. V. A1 - Koltsova, Tatiana S. A1 - Ginzburg, S. A. A1 - Michailov, Vesselin T1 - Effect of alumina addition on weld deposits microstructure at the welding of carbon steel T2 - Materials Physics and Mechanics N2 - The formation of acicular ferrite in the structure of weld deposits when welding carbon steels is often associated with the introduction of nonmetallic additives into the electrode material. Fe–alumina composite powders with alumina particles less than 1 µm were used as a filler for cored welding wire and the influence of aluminum oxide additives up to 2,5 wt.% on the structure of the welded seam was studied. It was shown that the addition of aluminum oxide to the welding wire led to the initiation of the formation of intragranular acicular ferrite in the weld deposit and to a more even distribution of hardness through the zones of weld seam. KW - acicular ferrite KW - alumina KW - welding KW - carbon steel Y1 - 2018 U6 - https://doi.org/10.18720/MPM.3812018_4 SN - 1605-8119 VL - Vol. 38 IS - 1 SP - 26 EP - 32 ER - TY - GEN A1 - Doynov, Nikolay A1 - Stapelfeld, Christoph A1 - Michailov, Vesselin A1 - Pasternak, Hartmut A1 - Launert, Benjamin ED - Sommitsch, Christof ED - Enzinger, Norbert ED - Mayr, Peter T1 - Distortion analysis of large scaled welded structures T2 - Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria N2 - The work presents an innovative approach for simulation of welding induced distortions, which allows taking into consideration the local effects of the welding process as well as the global interactions in the structure. The approach bases on an integration of analytical and numerical calculation’s procedures in a hybrid model, realized with the aid of the inherent strain concept. The analytical procedure calculates the shrinkage strain components and area of the plastic deformed zone, caused by welding. The calculated strains are then transferred to the global finite element model in order to predict the distortions and stresses in the structure after every welding stage, as well as their final state. The consideration of welding scenarios, weld sequence, clamping conditions and the assembling stages is done by taking into account the intermediate variation of the strain state during the manufacturing steps. The article gives the theoretical basis of the analytical model. The consideration of the essential physical relations is put into discussion. The application of the model is illustrated on complex structures. Its reliability and practicability are demonstrated by means of a validation study. Y1 - 2019 SN - 978-3-85125-615-4 U6 - https://doi.org/10.3217/978-3-85125-615-4 SP - 254 EP - 280 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - GEN A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Improve load capacity calculations by considering realistic imperfections induced by welding for plates and shells T2 - Stability and ductility of steel structures 2019 : proceedings of the International Colloquia on Stability and Ductility of Steel Structures (SDSS 2019), September 11-13, 2019, Prague, Czech Republic Y1 - 2019 UR - https://www.b-tu.de/fg-stahlbau/publikationen/veroeffentlichungen SN - 978-0-367-33503-8 SP - 1059 EP - 1067 PB - CRC Press CY - Boca Raton ER - TY - GEN A1 - Naumov, Anton A1 - Morozova, Iuliia A1 - Rylkov, Evgenii A1 - Obrosov, Aleksei A1 - Isupov, Fedor A1 - Michailov, Vesselin A1 - Rudskoy, Andrey I. T1 - Metallurgical and Mechanical Characterization of High-Speed Friction Stir Welded AA 6082-T6 Aluminum Alloy T2 - Materials N2 - The objective of this study was to investigate the effect of the high welding speed on the mechanical properties and their relations to microstructural characteristics of butt friction stir welded joints with the use of 6082-T6 aluminum alloy. The aluminum sheets of 2.0 mm thick were friction stir welded at low (conventional FSW) and high welding speeds (HSFSW) of 200 and 2500 mm/min, respectively. The grain size in the nugget zone (NZ) was decreased; the width of the softened region was narrowed down as well as the lowest microhardness value located in the heat-affected zone (HAZ) was enhanced by HSFSW. The increasing welding speed resulted in the higher ultimate tensile strength and lower elongation, but it had a slight influence on the yield strength. The differences in mechanical properties were explained by analysis of microstructural changes and tensile fracture surfaces of the welded joints, supported by the results of the numerical simulation of the temperature distribution and material flow. The fracture of the conventional FSW joint occurred in the HAZ, the weakest weld region, while all HSFSW joints raptured in the NZ. This demonstrated that both structural characteristics and microhardness distribution influenced the actual fracture locations. KW - high-speed friction stir welding (HSFSW) KW - aluminum alloy KW - remnant oxide line (ROL) KW - microstructural characteristics KW - mechanical properties KW - fracture behavior KW - FEM Y1 - 2019 UR - https://www.mdpi.com/1996-1944/12/24/4211 U6 - https://doi.org/10.3390/ma12244211 SN - 1996-1944 VL - 12 IS - 24 ER - TY - GEN A1 - Morozova, Iuliia A1 - Bonnel, Jean-Marie A1 - Rosert, Reinhard A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin T1 - Einfluss der Schweißposition beim MSG-Fülldrahtschweißen auf die Kerbschlagzähigkeit von hoch- und niedriglegierten Stählen T2 - DVS Congress 2019Große Schweißtechnische Tagung : DVS-Studentenkongress : Vorträge der Veranstaltungen in Düsseldorf vom 16. bis 17. September 2019 N2 - Die Schweißposition beeinflusst erheblich die mechanischen Eigenschaften der Schweißnaht, insbesondere die Kerbschlagzähigkeit. Dies zeigt ein umfassender Vergleich der mechanischen Eigenschaften von Schweißgütern, die in der Steigposition (PF) und Wannenlage (PA) ausgeführt wurden. Schweißgüter von Kohlenstoff-Mangan-Stählen weisen in der PF-Position eine reduzierte Kerbschlagarbeit im Vergleich zur PA-Position auf. Dagegen ist bei austenitischen und Duplexstählen der Einfluss der Schweißposition auf die Kerbschlagarbeit genau entgegengesetzt. Der Vortrag fasst den Einfluss der Schweißpositionen auf die mechanischen Eigenschaften zusammen und liefert eine Erklärung für die gegensätzlichen Auswirkungen auf die Kerbschlagzähigkeit der Schweißgüter. Der Schwerpunkt liegt dabei auf hochlegierten Fülldrähten mit einer schnell erstarrenden Schlacke. Die Schlackeneigenschaften, Schweißgutmikrostruktur, Delta-Ferrit-Gehalte für Schweißgüter vom Typ Duplexstahl (2209) und von austenitischen Schweißgütern (308L) sowie die Auswirkungen der Schweißposition auf die Richtung des Schweißkornwachstums werden erläutert. Zum Vergleich werden Kohlenstoff-Mangan-Rutil-Fülldrähte mit schnell erstarrender Schlacke herangezogen. Y1 - 2019 UR - https://www.gbv.de/dms/tib-ub-hannover/1067034390.pdf SN - 978-3-96144-066-5 SP - 310 EP - 318 PB - DVS Media GmbH CY - Düsseldorf ER - TY - GEN A1 - Naumov, Anton A1 - Morozova, Iuliia A1 - Isupov, Fedor A1 - Golubev, Iurii A1 - Michailov, Vesselin T1 - Temperature Influence on Microstructure and Properties Evolution of Friction Stir Welded Al-Mg-Si Alloy T2 - Key Engineering Materials N2 - The temperature influence on the microstructure evolution and microhardness of the agehardenable aluminium alloy 6082 T6 during friction stir welding was defined. In order to achieve this aim, the thermocycles calculated using the developed 3D Finite Element Model were physically simulated on the Gleeble-3800 in the points which located in the different zones of the weld. The microstructure in the chosen points after Gleeble testing was investigated as well as the microhardness was measured. The results were consequently compared with the relevant results obtained after friction stir welding. It was shown that the microstructure and microhardness profile are influenced not only by temperature but by deformation. The increase in hardness in different zones after FSW compared to Gleeble testing can be explained by the grain refinement in the nugget zone as well as the hardening precipitate distribution along the weld which can occur more rapidly due to the deformation influence. Y1 - 2019 U6 - https://doi.org/10.4028/www.scientific.net/KEM.822.122 SN - 1662-9795 VL - 822 SP - 122 EP - 128 ER - TY - GEN A1 - Golubev, Iurii A1 - Morozova, Iuliia A1 - Naumov, Anton A1 - Hantelmann, Cord A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Numerical Simulation and Experimental Investigation on Impulse Friction Stir Welding of 6082-T6 Aluminum Alloy T2 - Papers from Materials Science and Technology 2017 (MS&T17), October 8 – 12, 2017, David L. Lawrence Convention Center, Pittsburgh, Pennsylvania USA N2 - The series of impulse friction stir welding (IFSW) experiments for aluminum alloy 6082-T6 butt joints was performed to obtain micrographs, tensile and hardness test samples and to receive the validation data for a numerical model of the process. Impulse force and frequency were varied to determine the effect of individual process parameters on microstructure evolution and mechanical properties of the welded butt joints. A three-dimensional model was established to simulate temperature distribution, heat generation and contact state between the tool and the workpiece during IFSW. Based on the numerical simulation, the influence of the impulses on heat input, maximum weld temperatures and contact state was found. The combination of impulse force and frequency effected the grain refinement. The influence of impulses on the elongation and hardness of the welded joints during IFSW were determined. Y1 - 2017 UR - https://www.researchgate.net/publication/326434324_Numerical_Simulation_and_Experimental_Investigation_on_Impulse_Friction_Stir_Welding_of_6082-T6_Aluminum_Alloy U6 - https://doi.org/10.7449/2017/mst_2017_987_994 SP - 987 EP - 994 ER - TY - GEN A1 - Evdokimov, Anton A1 - Ossenbrink, Ralf A1 - Doynov, Nikolay A1 - Michailov, Vesselin ED - Sommitsch, Christof ED - Enzinger, Norbert ED - Mayr, Peter T1 - Laser beam welding of steel-aluminum joints - influence of weld metal elastic-plastic properties on the distortions T2 - Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria N2 - Great attention is focused nowadays on laser welding of dissimilar steel-aluminum joints in overlap configuration in key-hole mode. It was found that elastic-plastic properties of the weld metal exhibit strong difference to those of the base alloys and can be defined as a function of aluminum content in the weld metal. A developed Finite-Element simulation model allows prediction of the aluminum content as a function of welding parameters and subsequently the elastic-plastic properties of the weld metal as a function of the determined content. The main goal of the present study is to show the impact of the weld metal properties on welding distortions and residual stresses. For that purpose, a sensitivity analysis of the thermomechanical model was performed, where the distortions and residual stresses were computed as a function of welding parameters and therefore as a function of corresponding weld metal properties. The analysis showed that the influence of the weld metal is essential, and its properties should be taken into consideration in the models for better prediction accuracy. Y1 - 2019 SN - 978-3-85125-615-4 U6 - https://doi.org/10.3217/978-3-85125-615-4 SP - 431 EP - 440 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - GEN A1 - Kaisheva, Darina A1 - Bokuchava, Gizo A1 - Papushkin, Igor A1 - Genchev, Gancho Vladimirov A1 - Doynov, Nikolay A1 - Ossenbrink, Ralf A1 - Michailov, Vesselin A1 - Petrov, Peter T1 - Determination of residual stresses in fiber laser welded stainless steel joints by neutron diffraction method T2 - Proc. SPIE 11047, 20th International Conference and School on Quantum Electronics: Laser Physics and Applications N2 - This study presents an experimental results of residual stress states in stainless steel plate samples with size 100 x 50 x 10 mm welded using a high-power fiber laser. The technological parameters of the welding process were: laser power Q = 15 kW; laser spot size = 0.65 mm; welding speed V = 3 m/min; 4 m/min; 5 m/min, using 30 L/min of protective Ar gas. The neutron diffraction method was used to determine the residual stresses in the bulk of the material. The neutron experiments were performed on the FSD diffractometer at the IBR-2 pulsed reactor in the Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research - Dubna, Russian Federation. The measured residual stress distributions exhibit maxima at weld seam centers. As expected, for all specimens the residual stress is falling down in regions distant from the weld zone. Maximal residual stress value of 492 MPa was observed for sample welded with speed of V = 5 m/min. KW - Diffraction KW - Laser welding KW - Metals KW - Fiber laser KW - Laser processing KW - Laser applications KW - Sensors Y1 - 2019 U6 - https://doi.org/10.1117/12.2516421 CY - Nessebar ER -