FG Metallische Werkstoffe

28 Items

Recent Submissions
Synchrotron Sub‐μ X‐ray Tomography of Kirkendall Porosity in a Diffusion Couple of Nickel‐Base Superalloy and Nickel after Annealing at 1250 °C

Epishin, Alexander ; Camin, Bettina ; Hansen, Lennart ; Chyrkin, Anton ; Nolze, Gert (2021-01-21)

Kirkendall porosity that forms during interdiffusion in a diffusion couple of nickel‐base superalloy CMSX‐10 with pure nickel is investigated. The diffusion experiments are conducted at a temperature of 1250 °C, where the strengthening γ′‐phase is partially dissolved. The porosity is studied by X‐ray sub‐μ tomography with a spatial resolution of about 0.353 μm3 at the European Synchrotron Radia...

Quantifizierung von Fehlstellen in teiltransparenten Festkörpern mittels der Impulsthermografie

Bernegger, Raphael Kim (2021)

Die Impulsthermografie (PT) gehört zu den zerstörungsfreien Prüfverfahren und wird für die Detektion und Quantifizierung von verdeckten Fehlstellen in einem Bauteil eingesetzt. Bei Materialien, die im Wellenlängenbereich der optischen Anregungsquelle und der Infrarot(IR)-Kamera teiltransparent sind, z.B. glasfaserverstärkter Kunststoff (GFK), können die bestehenden Auswertemethoden der PT nicht...

Microstructural Stability of Extruded Mg-Mn-Ce Hollow Profiles with Weld Seams

Gensch, Felix ; Gall, Sven ; Lechner, Stefan ; Fahrenson, Christoph ; Müller, Sören (2021-03-27)

Despite aluminum profiles, magnesium profiles have not been well developed due to the low formability. Furthermore, extruded magnesium profiles show a strong dependence on the mechanical properties, according to the loading direction. This is caused by a strong basal texture, which is directly dependent on the process parameters during the extrusion and the subsequent aging. Thus, the present p...

Adjustment of the Mechanical Properties of Mg2Nd and Mg2Yb by Optimizing Their Microstructures

Schmidt, Jonas ; Beyerlein, Irene J. ; Knezevic, Marko ; Reimers, Walter (2021-02-25)

The deformation behavior of the extruded magnesium alloys Mg2Nd and Mg2Yb was investigated at room temperature. By using in situ energy-dispersive synchrotron X-ray diffraction compression and tensile tests, accompanied by Elasto-Plastic Self-Consistent (EPSC) modeling, the differences in the active deformation systems were analyzed. Both alloying elements change and weaken the extrusion textur...

Investigation of Elastic Properties of the Single-Crystal Nickel-Base Superalloy CMSX-4 in the Temperature Interval between Room Temperature and 1300 °C

Epishin, Alexander ; Fedelich, Bernard ; Finn, Monika ; Künecke, Georgia ; Rehmer, Birgit ; Nolze, Gert ; Leistner, Claudia ; Petrushin, Nikolay ; Svetlov, Igor (2021-02-02)

The elastic properties of the single-crystal nickel-base superalloy CMSX-4 used as a blade material in gas turbines were investigated by the sonic resonance method in the temperature interval between room temperature and 1300 °C. Elastic constants at such high temperatures are needed to model the mechanical behavior of blade material during manufacturing (hot isostatic pressing) as well as duri...

Influence of die surface topography and lubrication on the product quality during indirect extrusion of copper-clad aluminum rods

Kuhnke, Stefan ; Gensch, Felix ; Nitschke, René ; Sanabria, Vidal ; Mueller, Soeren (2020-07-04)

Copper-clad aluminum rods are usually fabricated using hydrostatic extrusion, since during direct and indirect extrusion fracture of the copper sleeve is difficult to avoid. In this study, different die surface topographies and lubrication conditions were applied to improve the material flow during indirect extrusion of copper-clad aluminum rods. Thus, conic dies with different roughness (polis...

In Situ 3D-µ-Tomography on Particle-Reinforced Light Metal Matrix Composite Materials under Creep Conditions

Camin, Bettina ; Hansen, Lennart (2020-08-01)

In transportation light metal matrix composites (L-MMCs) are used increasingly due to their improved creep resistance even at higher application temperatures. Therefore, the creep behavior and failure mechanisms of creep loaded particle reinforced L-MMCs have been investigated intensively. Until now, creep damage analyses are usually performed ex situ by means of interrupted creep experiments. ...

Verhalten des hochwarmfesten Stahles P92 unter zyklischen thermo-mechanischen Bedingungen in lastflexiblen Dampfkraftwerken

Jürgens, Maria (2020)

Die Erzeugung von Erneuerbaren Energien unterliegt starken Schwankungen, die von konventionellen Kraftwerken ausgeglichen werden müssen, um das Stromnetz stabil zu halten. Für die konventionellen Kraftwerke bedeutet dies eine zunehmend zyklische Fahrweise, die zu häufigeren Last- und Temperaturwechseln führt. Von den eingesetzten Werkstoffen fehlen Daten zum Verhalten unter zyklischer Fahrweise...

Numerical Investigations on Material Flow During Indirect Extrusion of Copper-Clad Aluminum Rods

Kuhnke, Stefan ; Sanabria, Vidal ; Gensch, Felix ; Nitschke, Renè ; Müller, Sören (2020-06-09)

In the extrusion of clad composite materials with different flow stresses are usually used. This causes an inhomogeneous material flow which can induce sleeve or core fracture. In the present study, the material flow during indirect extrusion of copper-clad aluminum (CCA) rods was analyzed by means of experimental and numerical investigations throughout the process. In order to provide material...

Röntgenographische Analysen der Umformmechanismen und der Eigenspannungen umgeformter Bleche im Single Point Incremental Forming-Verfahren

Dobecki, Mateus (2020)

Die inkrementelle Blechumformung ist ein flexibles Fertigungsverfahren zur Herstellung komplex geformter Teile durch die kontrollierte Bewegung des Umformwerkzeugs. Die mechanischen Eigenschaften inkrementell umgeformter Bleche im Single Point Incremental Forming (SPIF)-Verfahren werden maßgeblich von den wirkenden Umformmechanismen während der Herstellung beeinflusst. In der vorliegenden Arbei...

Extrusion of Aluminum Tubes with Axially Graded Wall Thickness and Mechanical Characterization

Negendank, Maik ; Müller, Sören ; Reimers, Walter (2014-08-25)

In this study the indirect extrusion of seamless aluminum tubes with variable wall thickness was investigated. Therefore, an axially moveable stepped mandrel was applied. Investigations revealed that wall thickness transitions can either be graded over the tube length or very sharp. The microstructures in thin-walled and thick-walled tube sections were investigated. The local variation of the e...

Influence of choked angle of bearing channel on profile grain structure during multi-hole extrusion of aluminum alloy

Müller, Sören ; Sanabria, Vidal (2018-08-11)

Direct extrusion of aluminum alloy EN AW-6060 was carried out applying a four-hole die with pair-wise parallel and choked long channels. Due to the dissimilar friction inside parallel and choked channels profiles with different length were extruded simultaneously. In order to investigate the grain structure evolution along the whole extrusion process, multiple sections from the beginning to the...

Application of Friction Shear Test for Constitutive Modeling Evaluation of Magnesium Alloy AZ31B at high Temperature

Sanabria, Vidal ; Gensch, Felix ; Müller, Sören (2020-04-26)

The experimental determination of the flow stress and its mathematical formulation are essential for the numerical simulation of metal forming processes. The hot compression test is widely used to analyze the flow stress evolution as function of temperature, strain and strain rate. The compression test is limited to a relative low strain (ε≤1) which is acceptable when the stress is minor influe...

Microstructure Evolution of Friction Boundary Layer during Extrusion of AA 6060

Sanabria, Vidal ; Müller, Sören ; Reimers, Walter (2014-10-14)

The tribological behavior between the aluminium alloy AA 6060 and the hot working steel 1.2344 has been recently studied using a new axial friction test for extrusion processes. With this new test, the friction forces as well as the specimens’ plastic deformations generated during sliding tests can be investigated. Selected specimens tested at high temperature (300-500 °C), normalized normal st...

Backward rod extrusion of bimetallic aluminum-copper alloys at room temperature

Sanabria, Vidal ; Gall, Sven ; Gensch, Felix ; Nitschke, René ; Müller, Sören (2019-07-02)

The backward rod extrusion of bimetallic aluminum-copper alloys at room temperature was investigated. The aluminum alloy EN AW-1080A and the copper alloy Cu-ETP were selected to prepare the core and sleeve of the billet respectively. The copper cross section was equivalent to 30% of the billet. Moreover, the billet was extruded applying a conic die angle of 90° and an extrusion ratio of 14:1. E...

Extrusion of magnesium alloy hollow profiles with axial variable wall thickness

Negendank, Maik ; Sanabria, Vidal ; Müller, Sören ; Reimers, Walter (2019-07-02)

Industrially extruded profiles are characterized by a constant cross section along the length since rigid dies are applied in the process. However, if it would be possible to extrude profiles with cross sections that can be locally adapted (tailored) to the acting forces or stresses this would mean a significant potential for weight and material savings. Hence, in this study the extrusion of ma...

Analysis of the flow imbalance on the profile shape during the extrusion of thin magnesium sheets

Gall, Sven ; Müller, Sören ; Reimers, Walter (2013-12-31)

The extrusion process facilitates the production of magnesium sheets featuring a very thin thickness as well as excellent surface properties by using a single process step only. However, the extrusion of the magnesium sheets applying not optimized process parameters, e.g. low billet temperature or/ and poorly deformable magnesium alloy, produce pronounced buckling and waving of the extruded she...

Modification of the anisotropy and strength differential effect of extruded AZ31 by extrusion-shear

Jähnke, Martin ; Gensch, Felix ; Müller, Sören (2018-05-03)

The extrusion of magnesium alloys results in a pronounced fiber texture in which the basal planes are mostly oriented parallel and the c-axes are oriented perpendicular to the extrusion direction. Due to this texture the Strength Differential Effect (SDE), which describes the strength difference between tensile and compression yield strength, and the elastic anisotropy in the sheet plane are ob...

Influence of temperature and sliding speed on the subsurface microstructure evolution of EN AW-6060 under sticking friction conditions

Sanabria, Vidal ; Müller, Sören (2017-10-16)

The microstructure evolution of the friction boundary layer of the aluminum alloy EN AW-6060 was investigated. Sticking friction tests at different temperatures and sliding speeds were carried out. A severe deformation below the friction surface was observed by means of LOM and EBSD mapping. Thus, the thickness variation and the grain structure of the high deformation zone could be described. F...

Influence of the Microstructure and Silver Content on Degradation, Cytocompatibility, and Antibacterial Properties of Magnesium-Silver Alloys In Vitro

Liu, Zhidan ; Schade, Ronald ; Luthringer, Bérengère ; Hort, Norbert ; Rothe, Holger ; Müller, Sören ; Liefeith, Klaus ; Willumeit-Römer, Regine ; Feyerabend, Frank (2017-06-22)

Implantation is a frequent procedure in orthopedic surgery, particularly in the aging population. However, it possesses the risk of infection and biofilm formation at the surgical site. This can cause unnecessary suffering to patients and burden on the healthcare system. Pure Mg, as a promising metal for biodegradable orthopedic implants, exhibits some antibacterial effects due to the alkaline ...