TY - JOUR A1 - Boateng, Francis Twumasi A1 - Ewert, Uwe A1 - Kannengießer, Thomas A1 - Zscherpel, Uwe A1 - Griesche, Axel A1 - Kromm, Arne A1 - Hohendorf, Stephan A1 - Redmer, Bernard T1 - Real-time radiography for observation of crack growth during GTA (Gas Tungsten Arc) welding N2 - In situ crack detection in the mushy zone and the solid weld of a gas tungsten arc (GTA) weld using X-ray imaging during welding is a new research area for NDT inspection. Usually, NDT flaw detection is done after the complete solidification of the weld seam. In this paper, we present the use of real-time radiography with a minifocus X-ray source (YXLON X-ray tube Y.TU 225-D04) and a 75μm pixel size digital detector array (Dexela 1512) for the acquisition of 2D radiographic images by a sequence of exposures with time intervals of 80 ms for hot crack detection during single pass bead-on-plate GTA welding of 3 mm thick plates of aluminium alloy AlMgSi (6060). An analysis of the crack distribution in the weld sample is conducted from the acquired 2D radiographs and its corresponding 3D volumetric reconstruction achieved by linear coplanar digital laminography. This in situ approach opens new possibilities in the field of hot crack research by having the direct information of both the crack initiation and growth and its correlation to the welding parameters. KW - Hot cracking KW - Radiography KW - GTA welding KW - Aluminium alloys KW - Real-time operation PY - 2016 U6 - https://doi.org/10.1007/s40194-016-0351-7 SN - 0043-2288 SN - 1878-6669 VL - 60 IS - 5 SP - 931 EP - 937 AN - OPUS4-37128 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Schriever, Sina A1 - Piesker, Benjamin A1 - Skrotzki, Birgit T1 - Microstructure evolution in aluminium alloy 2618 A during ageing and creep N2 - The Microstructure Evolution in Aluminium Alloy 2618 A during Ageing and Creep was presented and discussed. T2 - Microscopy & Microanalysis 2016 CY - Columbus, OH, USA DA - 24.07.2016 KW - Aluminium alloys KW - Coarsening KW - Transmission electron microscopy PY - 2016 AN - OPUS4-38268 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rockenhäuser, Christian A1 - Skrotzki, Birgit T1 - Quantitative dark-field transmission electron microscopy of the microstructure evolution in a 2618A aluminum alloy during ageing N2 - Quantitative Dark-Field Transmission Electron Microscopy of the Microstructure Evolution in a 2618A Aluminum Alloy During Ageing was presented and discussed. T2 - Microscopy & Microanalysis 2016 CY - Columbus, OH, USA DA - 24.07.2016 KW - Aluminium alloys KW - Coarsening KW - Transmission electron microscopy KW - Dark-field transmission electron miscoscopy KW - Material degradation PY - 2016 U6 - https://doi.org/10.1017/S1431927616007145 VL - 2016 SP - Paper 1260 AN - OPUS4-38279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cabeza, Sandra A1 - Müller, Bernd R. A1 - Pereyra, R. A1 - Fernández, R. A1 - González-Doncel, G. A1 - Bruno, Giovanni T1 - Evidence of damage evolution during creep of Al–Mg alloy using synchrotron X-ray refraction N2 - In order to provide further evidence of damage mechanisms predicted by the recent solid-state transformation creep (SSTC) model, direct observation of damage accumulation during creep of Al–3.85Mg was made using synchrotron X-ray refraction. X-ray refraction techniques detect the internal specific surface (i.e. surface per unit volume) on a length scale comparable to the specimen size, but with microscopic sensitivity. A significant rise in the internal specific surface with increasing creep time was observed, providing evidence for the creation of a fine grain substructure, as predicted by the SSTC model. This substructure was also observed by scanning electron microscopy KW - Aluminium alloys KW - Creep KW - Damage KW - Synchrotron X-ray refraction KW - Electron microscopy KW - subgrain structure PY - 2018 U6 - https://doi.org/10.1107/S1600576718001449 SN - 1600-5767 VL - 51 SP - 420 EP - 427 PB - Wiley AN - OPUS4-44619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nadammal, Naresh A1 - Kailas, Satish A1 - Szpunar, Jerzy A1 - Suwas, Satyam T1 - Development of microstructure and texture during single and multiple pass friction stir processing of a strain hardenable aluminium alloy N2 - In the present study, microstructure and texture development during single and multiple pass friction stir processing (FSP) of a strain hardenable wrought AlMg alloy (AA5086) was investigated. Subtle differences were observed while comparing with heat treatable alloys in the nucleation mechanism of the recrystallized microstructure observed in the nugget zone. Strain induced boundary migration was the dominant mechanism of microstructure evolution in the alloy, which influenced the crystallographic texture development by weakening it. Micro-texture measurements reveal variations in the crystallographic texture along the thickness of the sample. Recrystallization texture components were observed in the nugget zone indicative of a pronounced static recrystallization in the alloy as compared to the heat treatable alloys. Bulk texture measurements within the nugget zone of the optimally processed sample reveal a relatively dominant C component of shear texture. Average grain size in the nugget zone remained the same and the bulk crystallographic texture components were retained during multiple-pass FSP. The lower strain energies involved and the enhanced recovery processes due to the high temperature materials processing of the alloy during FSP resulted in a stable microstructure and texture. In summary, FSP could be promoted as a competent and suitable secondary processing technique for the bulk production of ultra-fine-grained materials in strain hardenable aluminium alloys. KW - Friction stir processing KW - Aluminium alloys KW - Electron back-scattered diffraction KW - Crystallographic texture KW - Dynamic recrystallization PY - 2018 UR - https://www.sciencedirect.com/science/article/pii/S1044580317336136 U6 - https://doi.org/10.1016/j.matchar.2018.03.044 SN - 1044-5803 SN - 1873-4189 VL - 140 SP - 134 EP - 146 PB - Elsevier B.V CY - Amsterdam, The Netherlands AN - OPUS4-45125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Bernd R. A1 - Cabeza, Sandra A1 - Pereyra, R. A1 - Fernández, R. A1 - González-Doncel, G. A1 - Kupsch, Andreas A1 - Bruno, Giovanni T1 - Evidence of damage evolution during creep of Al–Mg alloy using synchrotron X-ray refraction N2 - In order to provide further evidence of damage mechanisms predicted by the solid-state transformation creep (SSTC) model, direct observation of damage accumulation during creep of Al–3.85Mg was made using synchrotron X-ray refraction (SXRR). X-ray refraction techniques capture the specific surface (i.e. surface per unit volume) with a field of view comparable to the specimen size but with microscopic sensitivity. A significant rise of the internal specific surface with increasing creep time was observed, providing evidence for the creation of a fine grain substructure, as predicted by the SSTC model. T2 - Tenth Joint BER II and BESSY II User Meeting CY - Berlin, Germany DA - 05.12.2018 KW - Aluminium alloys KW - Creep KW - Damage KW - Synchrotron X-ray refraction KW - Electron microscopy KW - Subgrain structure PY - 2018 AN - OPUS4-46861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fernández, R. A1 - Bokuchava, G. A1 - Bruno, Giovanni A1 - Serrano Munoz, Itziar A1 - González Doncel, G. T1 - On the dependence of creep-induced dislocation configurations on crystallographic orientation in pure Al and Al-Mg N2 - The peak broadening in neutron diffraction experiments on tensile specimens of pure Al (99.8%) and an Al-Mg alloy pre-deformed at different creep strains is analysed. These results are combined with the kernel angular misorientation of electron backscatter diffraction data from the creep-deformed microstructures. It is found that differently oriented grains possess different microstrains. These microstrains vary with creep strain in pure Al, but not in the Al-Mg alloy. It is proposed that this behaviour can explain the power-law breakdown in pure Al and the large creep strain observed in Al-Mg. The present findings further corroborate a description of the creep-induced dislocation structure as a fractal, predicated on previous work. KW - Creep KW - Aluminium alloys KW - Dislocations KW - Fractals KW - Diffraction peak width PY - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-575527 SN - 0021-8898 VL - 56 IS - Pt 3 SP - 764 EP - 775 AN - OPUS4-57552 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -