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Residual stress determination by neutron diffraction in low-carbon steel wires with accumulated shear deformation
Rogante, M. ; Mikula, Pavol ; Strunz, Pavel ; Zavdoveev, A.
Modern methods of severe plastic deformation (SPD) currently allow obtaining the ultrafine-grained (UFG) structure nearly in any material. In the manufacturing process of wire with UFG structure, a main restriction is the continuous drawing scheme in which this process occurs, thus it is important to consider the factors affecting the drawing efficiency. Despite the data on SPD steels such as strength, plasticity and conductivity, obtained by classical methodologies, further investigations are needed: a key information is the residual stresses (RS) status, and RS determination is an essential issue to improve knowledge of SPD effects. In this work, 15 wires samples made of low-alloyed quality structural steel Grade 08G2S GOST 1050 with accumulated shear deformation - as result of rolling with shear of the metal ingot and conventional wire drawing - have been investigated by neutron diffraction (ND). Results provide substantial data helping to evaluate the effect of shear deformation on RS of the considered steel, as well as additional support to complement the information already achieved by using the other characterization methodologies. Knowledge of the RS status can help developing a lowcarbon wire drawing technology with needed manufacturability and efficiency, playing a decisive role in the debugging of material selection and engineering design requirements.
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On the scientific utilisation of low power research reactors
Mikula, Pavol ; Strunz, Pavel
In our contribution we focus our attention on the scientific utilisation of the beam tubes at the low power research reactor LVR-15. Namely, it will be reported about the neutron scattering instrumentation development and the educational possibilities at the low power neutron sources. The feasibility of carrying out the methodology and instrumental development research at the low power neutron sources will be demonstrated on designs of several high resolution and good luminosity neutron scattering instruments exploiting Bragg diffraction optics. Some of them have been already realized e.g. for small angle neutron scattering studies or residual strain/stress measurements. As the mentioned instrumental development and testing can be carried out at the low power neutron sources, due to the much lower safety requirements in comparison with the medium and high flux sources, they offer excellent educational and training programmes in neutron scattering or imaging for students.
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Performance of self-developing radiography films in LVR-15's neutron beams
Šoltés, J. ; Viererbl, L. ; Klupák, V. ; Vinš, M. ; Michalcová, Božena
In the search for a suitable detector for demonstration neutron radiography measurements on the zero-power VR-1 training reactor at the Czech Technical University in Prague, some options were considered. Due to the reactor's low power and spatial limitations, an easy and practical solution had to be found. Self-developing films represent a flexible detection tool in x-ray imaging. Therefore, the goal of this study was to evaluate their potential for neutron detection. For this purpose, bare and converter covered films were studied in the thermal and epithermal neutron beams at the LVR-15 research reactor in Rez, Czech Republic.
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The activation of W and Zr by deuterons at energies up to 20 MeV
Šimečková, Eva ; Štefánik, Milan ; Bém, Pavel ; Mrázek, Jaromír ; Novák, Jan
The proton and deuteron induced reactions are of a great interest for the assessment of induced radioactivity of accelerator components, target and beam stoppers. In order to investigate the important nuclides, we have carried up the irradiation experiments with the variable-energy cyclotron U-120 M of the NPI CAS ež. The production cross sections of the nuclides 179,181,182m,182,183,184m,184,186Re and 187W from reaction on natural W were investigated by deuteron beams of 20 MeV energy. A part of preliminary results of deuteron activation of natural Zr is also shown. The stacked-foil technique was utilized. The comparison of present results to data of other authors and to predictions of evaluated data libraries is discussed.
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Proton and deuteron activation measurements at the NPI and future plans in SPIRAL2/NFS
Šimečková, Eva ; Bém, Pavel ; Mrázek, Jaromír ; Štefánik, Milan ; Běhal, Radomír ; Glagolev, Vadim
The proton- and deuteron-induced reactions are of a great interest for the assessment of induced radioactivity of accelerator components, target and beam stoppers as well as isotope production for medicine. In the present work, the deuteron-induced reaction cross sections on zinc were investigated by stacked-foil activation technique with deuteron beam of 20 MeV energy from the cyclotron U-120M of NPI CAS ež. Also the proton activation cross section measurement of iron is presented. The comparison of present results to data of other authors and to predictions of evaluated data libraries is discussed. The investigation shall continue for higher proton and deuteron energy interval 20-35 MeV at SPIRAL2/NFS facility using a charged particle irradiation chamber with pneumatic transport system to measure isotopes and isomers with half-lives in minutes-regions.
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Ion beams provided by small accelerators for material synthesis and characterization
Macková, Anna ; Havránek, Vladimír
The compact, multipurpose electrostatic tandem accelerators are extensively used for production of ion beams with energies in the range from 400 keV to 24 MeV of almost all elements of the periodic system for the trace element analysis by means of nuclear analytical methods. The ion beams produced by small accelerators have a broad application, mainly for material characterization (Rutherford Back-Scattering spectrometry, Particle Induced X ray Emission analysis, Nuclear Reaction Analysis and Ion-Microprobe with 1 um lateral resolution among others) and for high-energy implantation. Material research belongs to traditionally progressive fields of technology. Due to the continuous miniaturization, the underlying structures are far beyond the analytical limits of the most conventional methods. Ion Beam Analysis (IBA) techniques provide this possibility as they use probes of similar or much smaller dimensions (particles, radiation). Ion beams can be used for the synthesis of new progressive functional nanomaterials for optics, electronics and other applications. Ion beams are extensively used in studies of the fundamental energetic ion interaction with matter as well as in the novel nanostructure synthesis using ion beam irradiation in various amorphous and crystalline materials in order to get structures with extraordinary functional properties. IBA methods serve for investigation of materials coming from material research, industry, micro- and nano-technology, electronics, optics and laser technology, chemical, biological and environmental investigation in general. Main research directions in laboratories employing small accelerators are also the preparation and characterization of micro- and nano-structured materials which are of interest for basic and oriented research in material science, and various studies of biological, geological, environmental and cultural heritage artefacts are provided too.
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Calibration and Exact Characterization of Aerosol Deposit colected by SDI Impactor
Havránek, Vladimír
Ion beam analytical methods as PIXE (Particle induced X-ray emission), PIGE (Particle induced gamma-ray emission) and RBS (Rutherford backscattering spectrometry) are frequently used for elemental analysis of different types of atmospheric aerosol samples in a form of aerosol deposits on thin plastic filters or foils (Alfassi and Peisach, 1991, Johansson and Campbell, 1988). An ideal sample for analysis is thin homogeneous aerosol deposit with known deposit area. However in practice such samples are rare. They are often thick (more than limit for thin target approximation i.e. larger then few hundred micrograms per square centimetres), of irregular shape and unknown deposit area. In such conditions all obtained elemental mass results should be corrected for apparent deposit thickness, deposit homogeneity and effective deposit area.
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