@article{EvsevleevMishurovaCabezaetal.2018, author = {Evsevleev, Sergei and Mishurova, Tatiana and Cabeza, Sandra and Koos, R. and Sevostianov, Igor and Garc{\´e}s, Gonzales and Requena, Guillermo and Fernandez, R. and Bruno, Giovanni}, title = {The role of intermetallics in stress partitioning and damage evolution of AlSil2CuMgNi alloy}, series = {Materials Science and Engineering: A-Structural materials: properties, microstructure and processing}, volume = {736}, journal = {Materials Science and Engineering: A-Structural materials: properties, microstructure and processing}, publisher = {Elsevier}, address = {Lausanne}, issn = {0921-5093}, doi = {10.1016/j.msea.2018.08.070}, pages = {453 -- 464}, year = {2018}, abstract = {Load partitioning between phases in a cast AlSi12CuMgNi alloy was investigated by in-situ compression test during neutron diffraction experiments. Computed tomography (CT) was used to determine volume fractions of eutectic Si and intermetallic (IM) phases, and to assess internal damage after ex-situ compression tests. The CT reconstructed volumes showed the interconnectivity of IM phases, which build a 3D network together with eutectic Si. Large stresses were found in IMs, revealing their significant role as a reinforcement for the alloy. An existing micromechanical model based on Maxwell scheme was extended to the present case, assuming the alloy as a three-phase composite (Al matrix, eutectic Si, IM phases). The model agrees well with the experimental data. Moreover, it allows predicting the principal stresses in each phase, while experiments can only determine stress differences between the axial and radial sample directions. Finally, we showed that the addition of alloying elements not only allowed developing a 3D interconnected network, but also improved the strength of the Al matrix, and the ability of the alloy constituents to bear mechanical load.}, language = {en} } @article{SerranoMunozMishurovaThiedeetal.2020, author = {Serrano-Munoz, Itziar and Mishurova, Tatiana and Thiede, Tobias and Sprengel, Maximilian and Kromm, Arne and Nadammal, Naresh and Nolze, Gert and Saliwan-Neumann, Romeo and Evans, Alexander and Bruno, Giovanni}, title = {The residual stress in as-built laser powder bed fusion IN718 alloy as a consequence of the scanning strategy induced microstructure}, series = {Scientific reports}, volume = {10}, journal = {Scientific reports}, number = {1}, publisher = {Macmillan Publishers Limited, part of Springer Nature}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-020-71112-9}, pages = {15}, year = {2020}, abstract = {The effect of two types of scanning strategies on the grain structure and build-up of Residual Stress (RS) has been investigated in an as-built IN718 alloy produced by Laser Powder Bed Fusion (LPBF). The RS state has been investigated by X-ray diffraction techniques. The microstructural characterization was performed principally by Electron Backscatter Diffraction (EBSD), where the application of a post-measurement refinement technique enables small misorientations (< 2 degrees) to be resolved. Kernel average misorientation (KAM) distributions indicate that preferably oriented columnar grains contain higher levels of misorientation, when compared to elongated grains with lower texture. The KAM distributions combined with X-ray diffraction stress maps infer that the increased misorientation is induced via plastic deformation driven by the thermal stresses, acting to self-relieve stress. The possibility of obtaining lower RS states in the build direction as a consequence of the influence of the microstructure should be considered when envisaging scanning strategies aimed at the mitigation of RS.}, language = {en} } @article{MishurovaCabezaThiedeetal.2018, author = {Mishurova, Tatiana and Cabeza, Sandra and Thiede, Tobias and Nadammal, Naresh and Kromm, Arne and Klaus, Manuela and Genzel, Christoph and Haberland, Christoph and Bruno, Giovanni}, title = {The Influence of the Support Structure on Residual Stress and Distortion in SLM Inconel 718 Parts}, series = {Metallurgical and Materials Transactions A}, volume = {49A}, journal = {Metallurgical and Materials Transactions A}, number = {7}, publisher = {Springer}, address = {New York}, issn = {1073-5623}, doi = {10.1007/s11661-018-4653-9}, pages = {3038 -- 3046}, year = {2018}, abstract = {The effect of support structure and of removal from the base plate on the residual stress state in selective laser melted IN718 parts was studied by means of synchrotron X-ray diffraction. The residual stresses in subsurface region of two elongated prisms in as-built condition and after removal from the base plate were determined. One sample was directly built on a base plate and another one on a support structure. Also, the distortion on the top surface due to stress release was measured by contact profilometry. High tensile residual stress values were found, with pronounced stress gradient along the hatching direction. In the sample on support, stress redistribution took place after removal from the base plate, as opposed to simple stress relaxation for the sample without support. The sample on support structure showed larger distortion compared to sample without support. We conclude that the use of a support decreases stress values but stress-relieving heat treatments are still needed.}, language = {en} } @article{MishurovaStegemannLyamkinetal.2022, author = {Mishurova, Tatiana and Stegemann, Robert and Lyamkin, Viktor and Cabeza, Sandra and Evsevleev, Sergei and Pelkner, Matthias and Bruno, Giovanni}, title = {Subsurface and bulk residual stress analysis of S235JRC+C Steel TIG weld by diffraction and magnetic stray field measurements}, series = {Experimental mechanics : an international journal of the Society for Experimental Mechanics}, volume = {62}, journal = {Experimental mechanics : an international journal of the Society for Experimental Mechanics}, number = {6}, publisher = {Springer}, address = {New York}, issn = {0014-4851}, doi = {10.1007/s11340-022-00841-x}, pages = {1017 -- 1025}, year = {2022}, abstract = {Background Due to physical coupling between mechanical stress and magnetization in ferromagnetic materials, it is assumed in the literature that the distribution of the magnetic stray field corresponds to the internal (residual) stress of the specimen. The correlation is, however, not trivial, since the magnetic stray field is also influenced by the microstructure and the geometry of component. The understanding of the correlation between residual stress and magnetic stray field could help to evaluate the integrity of welded components. Objective This study aims at understanding the possible correlation of subsurface and bulk residual stress with magnetic stray field in a low carbon steel weld. Methods The residual stress was determined by synchrotron X-ray diffraction (SXRD, subsurface region) and by neutron diffraction (ND, bulk region). SXRD possesses a higher spatial resolution than ND. Magnetic stray fields were mapped by utilizing high-spatial-resolution giant magneto resistance (GMR) sensors. Results The subsurface residual stress overall correlates better with the magnetic stray field distribution than the bulk stress. This correlation is especially visible in the regions outside the heat affected zone, where the influence of the microstructural features is less pronounced but steep residual stress gradients are present. Conclusions It was demonstrated that the localized stray field sources without any obvious microstructural variations are associated with steep stress gradients. The good correlation between subsurface residual stress and magnetic signal indicates that the source of the magnetic stray fields is to be found in the range of the penetration depth of the SXRD measurements.}, language = {en} } @article{CabezaMishurovaGarcesetal.2017, author = {Cabeza, Sandra and Mishurova, Tatiana and Garc{\´e}s, Gonzales and Sevostianov, Igor and Requena, Guillermo and Bruno, Giovanni}, title = {Stress-induced damage evolution in cast AlSi12CuMgNi alloy with one- and two-ceramic reinforcements}, series = {Journal of materials science}, volume = {52}, journal = {Journal of materials science}, publisher = {Springer}, address = {New York}, issn = {0022-2461}, doi = {10.1007/s10853-017-1182-7}, pages = {10198 -- 10216}, year = {2017}, abstract = {Two composites, consisting of an as-cast AlSi12CuMgNi alloy reinforced with 15 vol\% Al2O3 short fibres and with 7 vol\% Al2O3 short fibres + 15 vol\% SiC particles, were studied. Synchrotron computed tomography disclosed distribution, orientation, and volume fraction of the different phases. In-situ compression tests during neutron diffraction in direction parallel to the fibres plane revealed the load partition between phases. Internal damage (fragmentation) of the Si phase and Al2O3 fibres was directly observed in CT reconstructions. Significant debonding between Al matrix and SiC particles was also found. Finally, based on the Maxwell scheme, a micromechanical model was utilized for the new composite with two-ceramic reinforcements; it rationalizes the experimental data and predicts the evolution of all internal stress components in each phase.}, language = {en} } @article{PauzonMishurovaEvsevleevetal.2021, author = {Pauzon, Camille and Mishurova, Tatiana and Evsevleev, Sergei and Dubiez-Le Goff, Sophie and Murugesan, Saravanakumar and Bruno, Giovanni and Hryha, Eduard}, title = {Residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion as a function of process atmosphere and component design}, series = {Additive manufacturing}, volume = {47}, journal = {Additive manufacturing}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2214-8604}, doi = {10.1016/j.addma.2021.102340}, pages = {10}, year = {2021}, abstract = {The influence of the process gas, laser scan speed, and sample thickness on the build-up of residual stresses and porosity in Ti-6Al-4V produced by laser powder bed fusion was studied. Pure argon and helium, as well as a mixture of those (30\% helium), were employed to establish process atmospheres with a low residual oxygen content of 100 ppm O-2. The results highlight that the subsurface residual stresses measured by X-ray diffraction were significantly lower in the thin samples (220 MPa) than in the cuboid samples (645 MPa). This difference was attributed to the shorter laser vector length, resulting in heat accumulation and thus in-situ stress relief. The addition of helium to the process gas did not introduce additional subsurface residual stresses in the simple geometries, even for the increased scanning speed. Finally, larger deflection was found in the cantilever built under helium (after removal from the baseplate), than in those produced under argon and an argon-helium mixture. This result demonstrates that complex designs involving large scanned areas could be subjected to higher residual stress when manufactured under helium due to the gas's high thermal conductivity, heat capacity, and thermal diffusivity.}, language = {en} } @article{ThiedeCabezaMishurovaetal.2018, author = {Thiede, Tobias and Cabeza, Sandra and Mishurova, Tatiana and Nadammal, Naresh and Kromm, Arne and Bode, Johannes and Haberland, Christoph and Bruno, Giovanni}, title = {Residual Stress in Selective Laser Melted Inconel 718}, series = {Materials performance and characterization}, volume = {7}, journal = {Materials performance and characterization}, number = {4}, publisher = {American Society for Testing and Materials}, address = {West Conshohocken}, issn = {2379-1365}, doi = {10.1520/MPC20170119}, pages = {717 -- 735}, year = {2018}, abstract = {The residual stress distribution in IN718 elongated prisms produced by selective laser melting was studied by means of neutron (bulk) and laboratory X-ray (surface) diffraction. Two deposition hatch lengths were considered. A horizontal plane near the top surface (perpendicular to the building direction) and a vertical plane near the lateral surface (parallel to the building direction) were investigated. Samples both in as-built (AB) condition and removed from the base plate (RE) were characterized. While surface stress fields seem constant for the AB condition, X-ray diffraction shows stress gradients along the hatch direction in the RE condition. The stress profiles correlate with the distortion maps obtained by tactile probe measurements. Neutron diffraction shows bulk stress gradients for all principal components along the main sample directions. We correlate the observed stress patterns with the hatch length, i.e., with its effect on temperature gradients and heat flow. The bulk stress gradients partially disappear after removal from the base plate.}, language = {en} } @article{FernandezCabezaMishurovaetal.2018, author = {Fernandez, R. and Cabeza, Sandra and Mishurova, Tatiana and Fernandez-Castrillo, P. and Gonzalez-Doncel, Gaspar and Bruno, Giovanni}, title = {Residual stress and yield strength evolution with annealing treatments in an age-hardenable aluminum alloy matrix composite}, series = {Materials Science and Engineering: A}, volume = {731}, journal = {Materials Science and Engineering: A}, publisher = {Elsevier}, address = {Lausanne}, issn = {0921-5093}, doi = {10.1016/j.msea.2018.06.031}, pages = {344 -- 350}, year = {2018}, abstract = {We investigated the possibility of minimizing tensile matrix residual stresses in age hardenable aluminum alloy metal matrix composites without detrimentally affect their mechanical properties (such as yield strength). Specifically, we performed thermal treatments at different temperatures and times in an age-hardenable aluminum matrix composite 2014Al-15vol\%Al2O3. Using X-ray synchrotron radiation diffraction and mechanical tests, we show that below a certain treatment temperature (250 degrees C) it is possible to identify an appropriate thermal treatment capable of relaxing residual stress in this composite while even increasing its yield strength, with respect to the as processed conditions.}, language = {en} } @article{MishurovaSydowThiedeetal.2020, author = {Mishurova, Tatiana and Sydow, Benjamin and Thiede, Tobias and Sizova, Irina and Ulbricht, Alexander and Bambach, Markus and Bruno, Giovanni}, title = {Residual stress and microstructure of a Ti-6Al-4V Wire Arc Additive Manufacturing hybrid demonstrator}, series = {Metals}, volume = {10}, journal = {Metals}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2075-4701}, doi = {10.3390/met10060701}, pages = {15}, year = {2020}, abstract = {Wire Arc Additive Manufacturing (WAAM) features high deposition rates and, thus, allows production of large components that are relevant for aerospace applications. However, a lot of aerospace parts are currently produced by forging or machining alone to ensure fast production and to obtain good mechanical properties; the use of these conventional process routes causes high tooling and material costs. A hybrid approach (a combination of forging and WAAM) allows making production more efficient. In this fashion, further structural or functional features can be built in any direction without using additional tools for every part. By using a combination of forging basic geometries with one tool set and adding the functional features by means of WAAM, the tool costs and material waste can be reduced compared to either completely forged or machined parts. One of the factors influencing the structural integrity of additively manufactured parts are (high) residual stresses, generated during the build process. In this study, the triaxial residual stress profiles in a hybrid WAAM part are reported, as determined by neutron diffraction. The analysis is complemented by microstructural investigations, showing a gradient of microstructure (shape and size of grains) along the part height. The highest residual stresses were found in the transition zone (between WAAM and forged part). The total stress range showed to be lower than expected for WAAM components. This could be explained by the thermal history of the component.}, language = {en} } @article{SerranoMunozFritschMishurovaetal.2020, author = {Serrano-Munoz, Itziar and Fritsch, Tobias and Mishurova, Tatiana and Trofimov, Anton and Apel, Daniel and Ulbricht, Alexander and Kromm, Arne and Hesse, Rene and Evans, Alexander and Bruno, Giovanni}, title = {On the interplay of microstructure and residual stress in LPBF IN718}, series = {Journal of materials science}, volume = {56}, journal = {Journal of materials science}, number = {9}, publisher = {Springer}, address = {New York}, issn = {0022-2461}, doi = {10.1007/s10853-020-05553-y}, pages = {5845 -- 5867}, year = {2020}, abstract = {The relationship between residual stresses and microstructure associated with a laser powder bed fusion (LPBF) IN718 alloy has been investigated on specimens produced with three different scanning strategies (unidirectional Y-scan, 90 degrees XY-scan, and 67 degrees Rot-scan). Synchrotron X-ray energy-dispersive diffraction (EDXRD) combined with optical profilometry was used to study residual stress (RS) distribution and distortion upon removal of the specimens from the baseplate. The microstructural characterization of both the bulk and the near-surface regions was conducted using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). On the top surfaces of the specimens, the highest RS values are observed in the Y-scan specimen and the lowest in the Rot-scan specimen, while the tendency is inversed on the side lateral surfaces. A considerable amount of RS remains in the specimens after their removal from the baseplate, especially in the Y- and Z-direction (short specimen dimension and building direction (BD), respectively). The distortion measured on the top surface following baseplate thinning and subsequent removal is mainly attributed to the amount of RS released in the build direction. Importantly, it is observed that the additive manufacturing microstructures challenge the use of classic theoretical models for the calculation of diffraction elastic constants (DEC) required for diffraction-based RS analysis. It is found that when the Reuss model is used for the calculation of RS for different crystal planes, as opposed to the conventionally used Kroner model, the results exhibit lower scatter. This is discussed in context of experimental measurements of DEC available in the literature for conventional and additively manufactured Ni-base alloys.}, language = {en} }