Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Akita, Koichi; Shibahara, Masakazu*; Ikushima, Kazuki*; Nishikawa, Satoru*; Furukawa, Takashi*; Suzuki, Hiroshi; Harjo, S.; Kawasaki, Takuro; Vladimir, L.*
Yosetsu Gakkai Rombunshu (Internet), 35(2), p.112s - 116s, 2017/06
Vladimir, L.*; Suzuki, Hiroshi
no journal, ,
The aim of our experimental research was to compare performance of the two systems, slit system and radial collimator, in typical applications. The study was carried out on Kowari diffractometer (OPAL research reactor, ANSTO) using two radial collimators temporary removed from RESA diffractometer (JRR-3, JAEA). A standard residual stress experiment was performed using both the radial collimators system with gauge volume 0.5, 3 and 5 mm and the slit system with the same gauge volume parameters. The performance of the both system was judged by comparing statistics precision, resolution and the effect of partial illumination in near-to-surface positions of the gauge volume. As a result, the large type radial collimator system is advantage in strain measurements of large samples to prevent bumping sample to optical devices, while the slit system is advantage in strain measurements in small samples to have good counting statistics.
Suzuki, Hiroshi; Akita, Koichi; Vladimir, L.*
no journal, ,
Problems in neutron strain measurement with large gauge volume were discussed based on strain measurements of a 50 mm thick bent bar and an annealed specimens using the TOF and the angular dispersive methods. It was experimentally verified that the change in the neutron-weighted center of gravity position (ncog position) by the neutron attenuation effect caused an apparent shift in strain distribution due to the weighted average effect in the gauge volume. Furthermore, typical pseudo-strain distribution near the sample surface due to the geometrical effect was observed in a surface strain scanning, and the pseudo-strains were also observed even when perfectly immersing the gauge volume in the sample due to a change in a ncog position by the neutron attenuation effect. The trend and magnitude of the pseudo-strain distribution were shifted with a change in the gauge size, and it can be explained by typical modeling with consideration of effects of the incident neutron beam divergence and the wavelength distribution at the edge around a gauge volume.
Akita, Koichi; Suzuki, Hiroshi; Nishikawa, Satoru*; Moriai, Atsushi; Harjo, S.; Vladimir, L.*
no journal, ,
The materials used for the dissimilar weld joint were a SUS316L stainless steel and a NCF600 nickel alloy for the base plates, and an Alloy82 nickel alloy for the weld metal. The ultrasonic shot peening (USP) was applied to the sample surface after welding. The residual stress mappings of the as-peened and heat treated (593 K, 2 h) samples were measured at room temperature using KOWARI in ANSTO. In the results, the reduction of the tensile residual stress was observed near the interface of the weld metal and the nickel base plate. To clarify the relaxation process, the in-situ stress measurements during thermal cycles from RT to 593 K were conducted using TAKUMI in J-PARC. The effects of the difference in thermal expansion coefficient of the materials and the temperature dependence of the yield strength on the residual stress relaxation were disscussed based on the experimental results.