@misc{AtangaZhangDreibatietal., author = {Atanga, Valetine Kubong and Zhang, Wei and Dreibati, Ossama and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin and Scheffler, Michael}, title = {Alumina-mullite Materials for Refractory Applications: Microstructure, Physical and Finite Element Simulation of Thermal Shock Behaviour}, series = {refractories WORLDFORUM}, volume = {4}, journal = {refractories WORLDFORUM}, number = {1}, issn = {1868-2405}, pages = {159 -- 164}, language = {en} } @misc{GenchevDoynovOssenbrinketal., author = {Genchev, Gancho Vladimirov and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Modelling the Local Microstructure Properties due to Multi-Pass Welding}, series = {Materials Science Forum}, volume = {Vol. 879}, journal = {Materials Science Forum}, issn = {0255-5476}, doi = {10.4028/www.scientific.net/MSF.879.595}, pages = {595 -- 600}, language = {en} } @inproceedings{SeidlitzFritzscheSchleussetal., author = {Seidlitz, Holger and Fritzsche, Sebastian and Schleuß, Leander and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Neuartige F{\"u}getechnologie zum Herstellen von hochbelastbaren Multi-Material-Bauweisen aus textilverst{\"a}rkten Kunststoffen und Metallen bei einseitiger Zug{\"a}nglichkeit der F{\"u}gestelle}, series = {DVS Congress 2016, Große Schweißtechnische Tagung, Vortr{\"a}ge der Veranstaltungen in Leipzig am 19. und 20. September 2016}, booktitle = {DVS Congress 2016, Große Schweißtechnische Tagung, Vortr{\"a}ge der Veranstaltungen in Leipzig am 19. und 20. September 2016}, publisher = {DVS-Verlag}, address = {D{\"u}sseldorf}, isbn = {978-3-945023-74-7}, pages = {424 -- 428}, language = {de} } @inproceedings{GenchevDoynovOssenbrinketal., author = {Genchev, Gancho Vladimirov and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Schweißtechnische Simulation der lokalen Eigenschaften in der W{\"a}rmeeinflusszone von Mehrlagenschweißungen}, series = {ANSYS Conference \& 33rd CADFEM Users' Meeting, 24. - 26. Juni, Bremen, conference proceedings}, booktitle = {ANSYS Conference \& 33rd CADFEM Users' Meeting, 24. - 26. Juni, Bremen, conference proceedings}, publisher = {CADFEM GmbH}, address = {Grafing}, language = {de} } @misc{GenchevDoynovOssenbrinketal., author = {Genchev, Gancho Vladimirov and Doynov, Nikolay and Ossenbrink, Ralf and Bokuchava, Gizo and Petrov, Peter and Michailov, Vesselin}, title = {Numerical and Experimental Study of Residual Stress Distribution in Laser Beam Welded Joint}, pages = {S. 20}, language = {en} } @misc{SchleussRichterOssenbrinketal., author = {Schleuß, Leander and Richter, Thomas and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Plasma Cutting of Structured Sheet Metals in Comparison with Laser Beam Cutting}, series = {Journal of Materials Science and Engineering}, volume = {5}, journal = {Journal of Materials Science and Engineering}, number = {3-4}, issn = {2161-6221}, doi = {10.17265/2161-6221/2015.3-4.004}, pages = {135 -- 144}, language = {en} } @misc{NikitinSchleussOssenbrinketal., author = {Nikitin, Alexander and Schleuß, Leander and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Corrosion Behavior of Brazed Zinc-Coated Structured Sheet Metal}, series = {International Journal of Corrosion}, volume = {2017}, journal = {International Journal of Corrosion}, issn = {1687-9333}, doi = {10.1155/2017/4768505}, pages = {4768505}, language = {en} } @inproceedings{ZhangPrieferOssenbrinketal., author = {Zhang, Wei and Priefer, Marian and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Neue M{\"o}glichkeiten f{\"u}r die Additive Fertigung durch Laser-Pulver-Auftragschweißen}, series = {DVS Congress 2017, Große Schweißtechnische Tagung, DVS Studentenkongress, Vortr{\"a}ge der Veranstaltungen in D{\"u}sseldorf vom 26. bis 29. September 2017}, booktitle = {DVS Congress 2017, Große Schweißtechnische Tagung, DVS Studentenkongress, Vortr{\"a}ge der Veranstaltungen in D{\"u}sseldorf vom 26. bis 29. September 2017}, publisher = {DVS Media}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-008-5}, pages = {278 -- 282}, language = {de} } @misc{GenchevDoynovOssenbrinketal., author = {Genchev, Gancho Vladimirov and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin and Bokuchava, Gizo and Petrov, Peter}, title = {Residual stresses formation in multi-pass weldment: A numerical and experimental study}, series = {Journal of Constructional Steel Research}, volume = {138}, journal = {Journal of Constructional Steel Research}, issn = {0143-974X}, doi = {10.1016/j.jcsr.2017.08.017}, pages = {633 -- 641}, abstract = {In this study, the residual stresses distribution induced by multi-pass arc welding of the steel S355J2+N are investigated experimentally and numerically. An extended approach is used for the simulations, which considers the change of the local microstructure properties due to multiple reheating. Experimental material data obtained from physical welding simulations with Gleeble® are used for the model calibration. The experimental stress study is performed using a neutron diffraction method on a fourier stress diffractometer. Numerical analysis of the welding stresses formation in the weldment is performed and compared to the experimental study. The results explain the influence of the welding thermal history on the resulting local thermo-mechanical properties in the heat-affected zone and, thus, on the residual stress distribution. The consideration of the local microstructure properties in the welding simulation leads to a significant increase in accuracy of the numerical results. The major influence factor on the residual stress formation is the change in the interpass microstructure yield strength. When a root pass with short cooling times is subjected to re-austenitisation in the fine-grained zone, the yield strength increases in this area and affects consequently the residual stress distribution. The influence of the reheating is detectable in the depth of the weldment, but it is less significant for the residual stress formation near the surface of the welded joint.}, language = {en} } @misc{EvdokimovSpringerDoynovetal., author = {Evdokimov, Anton and Springer, Katrin and Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Heat source model for laser beam welding of steel-aluminum lap joints}, series = {International Journal of Advanced Manufacturing Technology}, volume = {93}, journal = {International Journal of Advanced Manufacturing Technology}, number = {1-4}, issn = {0268-3768}, doi = {10.1007/s00170-017-0569-6}, pages = {709 -- 716}, abstract = {In this study, a three-dimensional thermal conduction model based on the finite element analysis was established to predict a heat distribution during laser welding in overlap configuration of austenitic stainless steel 1.4301 and hardenable aluminum alloy 6016. A hybrid model based on two expanded curve-rotated volumetric heat sources is suggested to capture the complex weld geometry. Since thermal flow in the overlap area is a crucial part of the model, an analytic calculation of a thermal contact conductance between the plates and its subsequent implementation in the FE model through a superposition of two contact surfaces are described in details in this paper. Full thermal cycles, weld shapes, and thus mixing grades were successfully predicted by means of the developed model for different parameter combinations.}, language = {en} } @misc{EvdokimovObrosovOssenbrinketal., author = {Evdokimov, Anton and Obrosov, Aleksei and Ossenbrink, Ralf and Weiß, Sabine and Michailov, Vesselin}, title = {Mechanical properties of dissimilar steel-aluminum weld}, series = {Materials Science and Engineering: A}, volume = {Volume 722}, journal = {Materials Science and Engineering: A}, issn = {0921-5093}, doi = {https://doi.org/10.1016/j.msea.2018.03.019}, pages = {242 -- 254}, abstract = {Knowledge of the properties of dissimilar welds is of great significance for the development of multi-material lightweight structures. In this study, stainless steel (1.4301) and aluminum alloy (6082-T6) sheets were welded in overlap configuration in keyhole mode. The resulting weld metals were investigated with respect to their mechanical properties. Several samples were cut out of different locations along the welds and their cross-sections were subjected to indentation testing and energy dispersive X-ray (EDS) analysis. Young's modulus E, yield stress σy, and strain hardening exponent n, were determined by means of reverse analysis of the indentation load (P) - depth (h) curves, allowing construction of true stress - true strain relations. An essential increase in yield stress in comparison to the one of the base alloys was observed inside the weld metal. In contrary, Young's modulus and strain hardening exponent of the welds were almost identical to corresponding values of the base steel metal. Due to the sensitivity of yield stress to the aluminum content, slight variations of the welding parameters lead to significant changes in elastic-plastic behavior of the weld metal.}, language = {en} } @misc{MichailovOssenbrinkSchleussetal., author = {Michailov, Vesselin and Ossenbrink, Ralf and Schleuß, Leander and Springer, Katrin and Zoeke, J{\"o}rg}, title = {Strukturierte Tailored Blanks}, abstract = {Die Erfindung betrifft ein strukturiertes Tailored Blank, umfassend mindestens zwei F{\"u}gepartner, wobei mindestens ein F{\"u}gepartner ein strukturierter F{\"u}gepartner ist und wobei der strukturierte F{\"u}gepartner regelm{\"a}ßig angeordnete Versteifungselemente umfasst und wobei der strukturierte F{\"u}gepartner an mindestens einen weiteren F{\"u}gepartner gef{\"u}gt ist.}, language = {de} } @misc{MichailovFritzscheHantelmannetal., author = {Michailov, Vesselin and Fritzsche, Sebastian and Hantelmann, Cord and Ossenbrink, Ralf}, title = {Aluminium foam sandwiches for lightweight structures}, series = {Metal Science and Heat Treatment}, volume = {60}, journal = {Metal Science and Heat Treatment}, number = {1-2}, issn = {1573-8973}, doi = {10.1007/s11041-018-0238-x}, pages = {44 -- 49}, abstract = {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.}, language = {en} } @misc{WasilewskiWolfZhangetal., author = {Wasilewski, Eric and Wolf, Matthias and Zhang, Wei and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Cu/LaCrO₃ joining by local melt infiltration through laser cladding}, series = {Journal of the American Ceramic Society}, volume = {101}, journal = {Journal of the American Ceramic Society}, number = {10}, issn = {1551-2916}, doi = {10.1111/jace.15767}, pages = {4472 -- 4472}, abstract = {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.}, language = {en} } @inproceedings{GinzburgMorozovaKlosheketal., author = {Ginzburg, Svetlana and Morozova, Iuliia and Kloshek, Alexander and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Schweißen von Stahl mit Nanopartikel modifizierten F{\"u}lldr{\"a}hten - Schweißnahtgef{\"u}ge und -eigenschaften}, series = {DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vortr{\"a}ge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018}, booktitle = {DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vortr{\"a}ge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-036-8}, pages = {40 -- 46}, abstract = {Analyse des Schweißnahtgef{\"u}ges und -eigenschaften beim Schweißen von Stahl mit Nanopartikel modifizierten F{\"u}lldr{\"a}hten}, language = {de} } @inproceedings{FritzscheKloshekDietzetal., author = {Fritzsche, Sebastian and Kloshek, Alexander and Dietz, Eric and Michailov, Vesselin and Seidlitz, Holger and Ossenbrink, Ralf}, title = {SLM gefertigte Verbindungsknoten f{\"u}r Leichtbaurahmenelemente}, series = {DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vortr{\"a}ge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018}, booktitle = {DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vortr{\"a}ge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018}, number = {264}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-036-8}, abstract = {SLM gefertigte Verbindungsknoten f{\"u}r Leichtbaurahmenelemente}, language = {de} } @inproceedings{DoynovOssenbrinkMichailov, author = {Doynov, Nikolay and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Unterst{\"u}tzung beim thermischen Richten von geschweißten Großstrukturen durch praktikable Computersimulationen}, series = {DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vortr{\"a}ge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018}, booktitle = {DVS Congress 2018 : Große Schweißtechnische Tagung, DVS-Studentenkongress, Vortr{\"a}ge der Veranstaltungen in Friedrichshafen am 17. und 18. September 2018}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-036-8}, pages = {364 -- 369}, abstract = {Unterst{\"u}tzung beim thermischen Richten von geschweißten Großstrukturen durch praktikable Computersimulationen}, language = {de} } @misc{BokuchavaPetrovGenchevetal., author = {Bokuchava, Gizo and Petrov, Peter and Genchev, Gancho Vladimirov and Michailov, Vesselin and Doynov, Nikolay and Ossenbrink, Ralf}, title = {Residual stress analysis in welded joints by neutron difffraction and comouter modeling}, series = {Romanian Journal of Physics}, volume = {Vol. 63}, journal = {Romanian Journal of Physics}, number = {7-8}, issn = {1221-146X}, pages = {16}, abstract = {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.}, language = {en} } @misc{ZhangEvdokimovSchleussetal., author = {Zhang, Wei and Evdokimov, Anton and Schleuß, Leander and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Laser beam build-up welding of AlSi12-powder on AlSi1MgMn-alloy substrate}, series = {Progress in Additive Manufacturing}, volume = {4}, journal = {Progress in Additive Manufacturing}, number = {2}, issn = {2363-9512}, pages = {117 -- 129}, abstract = {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}, language = {en} } @misc{MorozovaBonnelRosertetal., author = {Morozova, Iuliia and Bonnel, Jean-Marie and Rosert, Reinhard and Ossenbrink, Ralf and Michailov, Vesselin}, title = {Einfluss der Schweißposition beim MSG-F{\"u}lldrahtschweißen auf die Kerbschlagz{\"a}higkeit von hoch- und niedriglegierten St{\"a}hlen}, series = {DVS Congress 2019Große Schweißtechnische Tagung : DVS-Studentenkongress : Vortr{\"a}ge der Veranstaltungen in D{\"u}sseldorf vom 16. bis 17. September 2019}, journal = {DVS Congress 2019Große Schweißtechnische Tagung : DVS-Studentenkongress : Vortr{\"a}ge der Veranstaltungen in D{\"u}sseldorf vom 16. bis 17. September 2019}, publisher = {DVS Media GmbH}, address = {D{\"u}sseldorf}, isbn = {978-3-96144-066-5}, pages = {310 -- 318}, abstract = {Die Schweißposition beeinflusst erheblich die mechanischen Eigenschaften der Schweißnaht, insbesondere die Kerbschlagz{\"a}higkeit. Dies zeigt ein umfassender Vergleich der mechanischen Eigenschaften von Schweißg{\"u}tern, die in der Steigposition (PF) und Wannenlage (PA) ausgef{\"u}hrt wurden. Schweißg{\"u}ter von Kohlenstoff-Mangan-St{\"a}hlen weisen in der PF-Position eine reduzierte Kerbschlagarbeit im Vergleich zur PA-Position auf. Dagegen ist bei austenitischen und Duplexst{\"a}hlen der Einfluss der Schweißposition auf die Kerbschlagarbeit genau entgegengesetzt. Der Vortrag fasst den Einfluss der Schweißpositionen auf die mechanischen Eigenschaften zusammen und liefert eine Erkl{\"a}rung f{\"u}r die gegens{\"a}tzlichen Auswirkungen auf die Kerbschlagz{\"a}higkeit der Schweißg{\"u}ter. Der Schwerpunkt liegt dabei auf hochlegierten F{\"u}lldr{\"a}hten mit einer schnell erstarrenden Schlacke. Die Schlackeneigenschaften, Schweißgutmikrostruktur, Delta-Ferrit-Gehalte f{\"u}r Schweißg{\"u}ter vom Typ Duplexstahl (2209) und von austenitischen Schweißg{\"u}tern (308L) sowie die Auswirkungen der Schweißposition auf die Richtung des Schweißkornwachstums werden erl{\"a}utert. Zum Vergleich werden Kohlenstoff-Mangan-Rutil-F{\"u}lldr{\"a}hte mit schnell erstarrender Schlacke herangezogen.}, language = {de} } @misc{EvdokimovOssenbrinkDoynovetal., author = {Evdokimov, Anton and Ossenbrink, Ralf and Doynov, Nikolay and Michailov, Vesselin}, title = {Laser beam welding of steel-aluminum joints - influence of weld metal elastic-plastic properties on the distortions}, series = {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}, journal = {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}, editor = {Sommitsch, Christof and Enzinger, Norbert and Mayr, Peter}, publisher = {Verlag der Technischen Universit{\"a}t Graz}, address = {Graz}, isbn = {978-3-85125-615-4}, doi = {10.3217/978-3-85125-615-4}, pages = {431 -- 440}, abstract = {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.}, language = {en} }