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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.
