STRESS-SPEC: Materials science diffractometer

Hofmann, M.; Gan, W. S.; Rebelo-Kornmeier, Joana

doi:10.17815/jlsrf-1-25

Cited by 24 publications

(16 citation statements)

References 2 publications

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“…Stress determination by neutron diffraction (ND) was carried out at the STRESS-SPEC diffraction instrument [25] at the neutron facility FRM II in Munich, Germany (Figure 2a). A bent Si 400 single crystal monochromator was used to select the wavelength of 1.550 Å.…”

Section: Neutron Diffractionmentioning

confidence: 99%

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Ulbricht

Altenburg

Sprengel

et al. 2020

Metals

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Rapid cooling rates and steep temperature gradients are characteristic of additively manufactured parts and important factors for the residual stress formation. This study examined the influence of heat accumulation on the distribution of residual stress in two prisms produced by Laser Powder Bed Fusion (LPBF) of austenitic stainless steel 316L. The layers of the prisms were exposed using two different border fill scan strategies: one scanned from the centre to the perimeter and the other from the perimeter to the centre. The goal was to reveal the effect of different heat inputs on samples featuring the same solidification shrinkage. Residual stress was characterised in one plane perpendicular to the building direction at the mid height using Neutron and Lab X-ray diffraction. Thermography data obtained during the build process were analysed in order to correlate the cooling rates and apparent surface temperatures with the residual stress results. Optical microscopy and micro computed tomography were used to correlate defect populations with the residual stress distribution. The two scanning strategies led to residual stress distributions that were typical for additively manufactured components: compressive stresses in the bulk and tensile stresses at the surface. However, due to the different heat accumulation, the maximum residual stress levels differed. We concluded that solidification shrinkage plays a major role in determining the shape of the residual stress distribution, while the temperature gradient mechanism appears to determine the magnitude of peak residual stresses.

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Section: Neutron Diffractionmentioning

confidence: 99%

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Ulbricht

Altenburg

Sprengel

et al. 2020

Metals

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“…The neutron diffraction measurement was done by the STRESS‐SPEC with the following parameters: neutron source Si (400) with λ = 0.167 nm, with a gauge volume of 1 × 5 × 1 mm 3 , and diffraction plane hkil = 30‐30 with a diffraction angle 2θ = 75°. The stresses were measured in nine specific areas on the ( X,Y ) plane (Figure ) and in the depths according to the Z axis at −0.5, −1.5,‐2.5 and −3.5 mm.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of residual stresses during brazing of Al₂O₃‐ZrO₂ to cemented tungsten carbide

Contarato

Bach

Krier

et al. 2019

Int J Applied Ceramic Tech

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In the context of the assembly of a cutting tool for wood machining, this article proposes to evaluate the residual stress in a ceramic plate (Al 2 O 3 -ZrO 2 ) induced by a brazing step with a cemented tungsten carbide (WC-Co) through a brazing filler (Ag-Cu-Ti). The residual stresses were evaluated using neutron and X-ray diffraction method. Moreover, a mathematical model was used in the case of a three layer assembly, which is based on mechanical properties such as: the thermal coefficient, the Young's modulus, the Poisson's ratio and the thickness of each layer. The observation of the chemical mapping of the brazing filler before and after the assembly, using energy dispersive X-ray spectroscopy (EDX), showed the chemical migration of the titanium to the ceramic oxide and the tungsten carbide. It was estimated that the brazed assembly is under a flexural stress, with a maximum in a compressive stress area near the brazing joint which reaches 85.6 MPa. This stress value reaches 12% of the bending strength allowed by the ceramic (716 MPa). The discussion proposes to highlight the limits of each method. The mathematical model has however shown good accuracy to give a first estimated residual stress in the ceramic plate. K E Y W O R D S ceramic-metal systems, modeling/model, neutron diffraction, stress, X-ray methods How to cite this article: Contarato F, Bach M, Krier J, Gobled A, Mille P. Evaluation of residual stresses during brazing of Al 2 O 3 -ZrO 2 to cemented tungsten carbide. Int J Appl Ceram Technol. 2020;17:990-997.

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“…Dilatometry was performed with a Linseis L75VD500 vertical, high-precision difference dilatometer (see [ 3 ]) under argon flow (5.0) at constant heating rates (between 1.5 and 10.0 K min ) from 273 to 773 K. The length change of the ultrafine-grained nickel samples was measured with respect to that of a reference HPT Ni-sample which was pre-annealed to a coarse-grained equilibrium state. The neutron diffraction measurements were performed at the STRESS-SPEC instrument of the FRM II [ 7 ]. The angle was measured for the reflection applying the method with 17 measurement points in intervals of [ 8 ].…”

Section: Methodsmentioning

confidence: 99%

Internal stress and defect-related free volume in submicrocrystalline Ni studied by neutron diffraction and difference dilatometry

Kotzurek

Hofmann

Simic

et al. 2017

Philosophical Magazine Letters

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A combined study of neutron diffraction and difference dilatometry on submicrocrystalline Ni prepared by high pressure torsion aims at studying the anisotropic behaviour during dilatometry and its relation to internal stress and structural anisotropy. Macroscopic stresses were undetectable in the dilatometer samples. Along with specific tests such as post cold-rolling, this shows that an observed anisotropic length change upon annealing is not caused by internal stress, but can be explained by the inherent microstructure, i.e. the anisotropic annealing of relaxed vacancies at grain boundaries of shape-anisotropic crystallites.

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STRESS-SPEC: Materials science diffractometer

Cited by 24 publications

References 2 publications

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Evaluation of residual stresses during brazing of Al₂O₃‐ZrO₂ to cemented tungsten carbide

Internal stress and defect-related free volume in submicrocrystalline Ni studied by neutron diffraction and difference dilatometry

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STRESS-SPEC: Materials science diffractometer

Cited by 24 publications

References 2 publications

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Separation of the Formation Mechanisms of Residual Stresses in LPBF 316L

Evaluation of residual stresses during brazing of Al2O3‐ZrO2 to cemented tungsten carbide

Internal stress and defect-related free volume in submicrocrystalline Ni studied by neutron diffraction and difference dilatometry

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Evaluation of residual stresses during brazing of Al₂O₃‐ZrO₂ to cemented tungsten carbide