atw - International Journal for Nuclear Power | 05.2020

More documents

Info

atw Vol. 65 (2020) | Issue 5 ı May RESEARCH AND INNOVATION 266 | Fig. 7. Nanoporosity development in metalic membrane. | Fig. 8. Precipitate dissolution in CMSX4 singlecrystal nickel-based superalloy. examples Figure 7 and Figure 8 show the results of studies of the nanoporosity in metallic membrane (where the aim of the experiment was to determine a dependence of the pore depth on the etching time by using SANS) and in-situ studies of hightemperature microstructure (precipitate dissolution in CMSX4 single-crystal nickel-based superalloy was investigated), respectively [17, 18]. 2.6 Strain/stress scanning in polycrystalline materials The dedicated two-axis diffractometer installed at the channel HK4 is equipped with bent Si and Ge perfect single crystal monochromators which are easily changeable according to the experimental requirements. The diffractometer is usually used for macro strain scanning of polycrystalline materials. An easy change of the instrument parameters permits one to use it also for another type of experiments, e.g. Bragg diffraction optics experiments. The diffractometer uses advantages coming from focusing both in real and momentum space and yields good resolution and luminosity, especially for samples of small dimensions [19]. The resolution properties of the device are reached in a limited range of momentum transfer for which the focusing conditions are optimized. The corresponding optimization can be done easily by using a remote control of the curvature of the monochromator. In the case of the strain scanning of the sample, the gauge volume is determined by two fixed Cd slits (2 to 5) mm x (3 to 30) mm in the incident and diffracted beams and the measurements are performed in the vicinity of the scattering angle of 2q S = 90°. For scanning the sample a x-y-z stage or ABB robot system (see Figure 9) can be used. The instrument is controlled by PC. The diffractometer has a changeable monochromator take-off angle and can be set and operate at a suitably chosen – neutron wavelength in the thermal neutron range from 0.1 nm to 0.235 nm. In the case of a-Fe and g-Fe samples it usually operates at the neutron wavelength of 0.235 nm, when providing a maximum detector signal and good resolution after diffraction on a-Fe(110) and/or g-Fe(111) lattice planes. By recent installation of the 2D-PSD (20 x 20 cm 2 , 2 mm spatial resolution), the acquisition of the data has been increased by a factor of 4. Depending on the sample-detector distance and the required resolution the PSD detector can cover from 10° to15° of the scattering angle 2q S . The quality of the instrument are supported by the experimental results of stress measurements obtained on the welded test-sample shown in Figures 10 and 11 [20]. The aim of the performed residual stress studies was to find optimum composition of the additive material for electrodes in order to decrease residual stresses in the vicinity of the foot of the welding joint and consequently, to increase the fatigue strength. For samples we used parent material Weldox 700/S690QL and X2CrNi12 (1.4003) and D4-6547 filler for electrodes. 2.7 High resolution diffraction for materials research Another high-resolution two-axis diffractometer optimized for investigation of elastic and plastic deformation studies in polycrystalline materials is installed at the channel HK9. The instrument is used especially for in-situ thermo-mechanical testing of materials, i.e. to study the deformation and transformation mechanisms of modern types of newly developed materials. Neutron diffraction performed in situ upon external loads brings a wide range of valuable structural and sub-structural parameters of the studied material which is easy to correlate with the parameters of the external load. The obtained microstructural parameters of the examined material can be directly compared with the para meters of micromechanical models. This approach brings a deeper understanding of processes ongoing in materials upon deformations, thermal treatments or phase transformations. The instrumental parameters are as | Fig. 9. Photo showing the ABB robot system and 2D-PSD detector. | Fig. 10. Photo of the fatigue test specimen and its dimensions. Research and Innovation On the Scientific Utilisation of Low Power Research Reactors ı Pavol Mikula and Pavel Strunz
atw Vol. 65 (2020) | Issue 5 ı May | Fig. 11. Residual stress distribution in the vicinity of the welds welded by D4-6547 filler material. Parent materials: Weldox 700/S690QL and X2CrNi12 (1.4003). follows: Horizontally and vertically focusing monochromator employing elastically bent Si single crystals, neutron wavelength – 1 Å ≤ l ≤ 2.7 Å, neutron flux at the sample position – 10 5 n.cm 2 .s -1 at l=2.3 Å, angular range of scattering angles – 25°< 2q S < 90° and resolution – 2·10 -3 ≤ Dd/d ≤ 3·10 -3 . The following sample environments are at a disposal: Two deformation rigs for uni-axial loading (tension or pressure; ± 20 kN and ± 60 kN), resistance heating (T < 1,200 °C) or hot-air heating (T < 300 °C), miniature deformation machine for uni-axial loading (tension, pressure; ± 10 kN) inside an Eulerian cradle, Eulerian cradle ( inner diameter of 400 mm, 0°< c
Page 1 and 2: nucmag.com 2020 5 ISSN · 1431-5254
Page 3 and 4: atw Vol. 65 (2020) | Issue 5 ı May
Page 5 and 6: Kommunikation und Training für Ker
Page 25: atw Vol. 65 (2020) | Issue 5 ı May
Page 59 and 60: Kommunikation und Training für Ker

atw - International Journal for Nuclear Power | 05.2020

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?