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Busi, M.*; Polatidis, E.*; Malamud, F.*; Kockelmann, W.*; Morgano, M.*; Kaestner, A.*; Tremsin, A.*; Kalentics, N.*; Log
, R.*; Leinenbach, C.*; et al.
Physical Review Materials (Internet), 6(5), p.053602_1 - 053602_8, 2022/05
被引用回数：7 パーセンタイル：68.86(Materials Science, Multidisciplinary)In this work we perform a neutron Bragg edge tomography of stainless steel 316L additive manufacturing samples, one as built via standard laser powder bed fusion, and one using the novel three-dimensional (3D) laser shock peening technique. First, we consider conventional attenuation tomography of the two samples by integrating the signal for neutron wavelengths beyond the last Bragg edge, to analyze the bulk density properties of the material. Second, we obtain strain maps for each of the tomography projections by tracking the wavelength of the strongest Bragg edge corresponding to the {111} lattice plane family. It is found that not only the volume of the sample where the shock peening treatment was carried out yields a higher bulk density, but also a deep and remarkable compressive strain region.
Busi, M.*; Kalentics, N.*; Morgano, M.*; Griffiths, S.*; Tremsin, A. S.*; 篠原 武尚; Log, R.*; Leinenbach, C.*; Strobl, M.*
Scientific Reports (Internet), 11, p.14919_1 - 14919_9, 2021/07
被引用回数：4 パーセンタイル：28.49(Multidisciplinary Sciences)Laser powder bed fusion is an additive manufacturing technique extensively used for the production of metallic components. Despite this process has reached a status at which parts are produced with mechanical properties comparable to those from conventional production, it is still prone to introduce detrimental tensile residual stresses towards the surfaces along the building direction, implying negative consequences on fatigue life and resistance to crack formations. Laser shock peening (LSP) is a promising method adopted to compensate tensile residual stresses and to introduce beneficial compressive residual stress on the treated surfaces. Using neutron Bragg edge imaging, we perform a parametric study of LSP applied to 316L steel samples produced by laser powder bed fusion additive manufacturing.
Busi, M.*; Kalentics, N.*; Morgano, M.*; Griffiths, S.*; Tremsin, A. S.*; 篠原 武尚; Log, R.*; Leinenbach, C.*; Strobl, M.*
Additive Manufacturing, 39, p.101848_1 - 101848_9, 2021/03
被引用回数：14 パーセンタイル：73(Engineering, Manufacturing)Laser powder bed fusion is an efficient technique for additive manufacturing of metallic materials. The quality of the material produced depends on the optimization of a large range of build parameters and the complex thermo- mechanical build process is prone to inducing detrimental material features such as porosity and residual stresses negatively affecting fatigue resistance and lifetime. Here we apply neutron Bragg edge radiography in a para- metric study on printing 316L steel. The parameters concerned are the laser scanning speed and strategy as well as the optional use of support structures. Analyses of the full field single shot wavelength-resolved Bragg edge radiography data enables to characterize local density inhomogeneities, as well as cracks, based on the long wavelength tail of the spectrum and variations of the stress field but also textural features based on the Bragg edge pattern. It is found that in the performed study not only respective differences in the residual stresses due to parameter variation are manifesting but also systematic irregularities due to machine imperfections (e.g. issues with the powder coater) are observed in the printed samples. The study supports the use of the parallel scanning strategy without supports and with the lower utilized scanning speed.
Morgano, M.*; Kalentics, N.*; Carminati, C.*; Capek, J.*; Makowska, M.*; Woracek, R.*; Maimaitiyili, T.*; 篠原 武尚; Loge, R.*; Strobl, M.*
Additive Manufacturing, 34, p.101201_1 - 101201_6, 2020/08
被引用回数：23 パーセンタイル：75.89(Engineering, Manufacturing)Additive manufacturing is a promising and rapidly rising technology in metal processing. However, besides a number of key advantages the constitution of a part through a complex thermo-mechanical process implies also some severe issues with the potential of impacting the quality of products. In laser powder bed fusion (LPBF) the repetitive heating and cooling cycles induce severe strains in the built material, which can have a number of adverse consequences such as deformation, cracking and decreased fatigue life that might lead to severe failure even already during processing. Here we demonstrate how lattice strains implied by LPBF and laser shock peening (LSP) can efficiently be characterized through diffraction contrast neutron imaging. Despite the spatial resolution need with regards to the significant gradients of the stress distribution and the specific microstructure, which prevent the application of more conventional methods, Bragg edge imaging succeeds to provide essential two-dimensionally spatial resolved strain maps in full field single exposure measurements.
Sales, M.*; 篠原 武尚; S
rensen, M. K.*; Knudsen, E. B.*; Tremsin, A.*; Strobl, M.*; Schmidt, S.*
Journal of Physics D; Applied Physics, 52(20), p.205001_1 - 205001_6, 2019/05
被引用回数：7 パーセンタイル：36.99(Physics, Applied)Three dimensional polarimetric neutron tomography is an emerging method for nondestructive investigation of magnetic field strength and direction distribution in three dimensions. It utilises the Larmor precession of the neutron spin in the presence of an external magnetic field and has so far been restricted to the measurement of magnetic fields weak enough to keep the neutron precession below the phase-wrapping limit at 180 degree. Through the use of polychromatic time-of-flight information in combination with an iterative forward model reconstruction algorithm we have gone beyond this limit, thereby vastly broadening the potential of the technique. We present the reconstructed magnetic field of a measured current carrying solenoid as a proof-of-principle for this novel method, as well as successfully applying the method to a simulated data set of a sample consisting of multiple magnetic domains.
Strobl, M.*; Heimonen, H.*; Schmidt, S.*; Sales, M.*; Kardjilov, N.*; Hilger, A.*; Manke, I.*; 篠原 武尚; Valsecchi, J.*
Journal of Physics D; Applied Physics, 52(12), p.123001_1 - 123001_14, 2019/03
被引用回数：18 パーセンタイル：23.45(Physics, Applied)While neutron imaging is a well established technique for investigations of inner structures and processes in materials, complex systems, and devices, the utilization of polarized neutron beams to visualize magnetic phenomena has been introduced only about a decade ago. In contrast to neutron scattering studies, where the interaction of the neutron's magnetic moment with magnetic states of matter has been exploited for a long time, the direct visualization of magnetic fields in neutron imaging is a relatively new field and is still developing. Here, we give an overview of the status and provide approaches to visualizing magnetic fields with polarized neutrons, together with a report on the latest developments in attempting to record neutron tomographies for 3D reconstructions of magnetic vector fields.
篠原 武尚; 廣井 孝介; 林田 洋寿*; Su, Y. H.; 甲斐 哲也; Parker, J. D.*; Sales, M.*; Strobl, M.*; Schmidt, S.*; 鬼柳 善明*
no journal, ,
Magnetic field imaging using polarized neutrons is an attractive technique for neutron imaging due to its capability to study magnetic field distributions not only in free space but also inside bulk materials. The use of a pulsed neutron beam with the polarization imaging technique allows us to analyze the wavelength dependent polarization efficiently and precisely and enables us to evaluate accumulated field strength along the beam trajectory. Recently, we have constructed a 3D polarization analysis apparatus at the RADEN beam line of the J-PARC Materials and Life Science Experimental Facility, which is the world's first dedicated pulsed neutron imaging instrument. In this presentation, we will introduce our pulsed polarized neutron imaging technique and show results of recent application studies and technical development.
