Evaluation of impact properties of weld joint of reactor pressure vessel steels with the use of miniaturized specimens

Abstract

The effects of specimen size and location of V-notch on the Charpy impact properties were investigated with different sizes of specimens, standard, CVN-1/2, CVN-1/3, and CVN-1.5 mm, for A533B steel, low Mn, high Cu, high phosphorus (P), and high Cu/P steel weld joint. A part of the specimens was irradiated with neutron at 563 K up to 8 6 10 19 n/cm 2 . The heat affected zone (HAZ) specimen is the best in the impact properties among the specimens of base metal, HAZ, and weld metal in the steels with 0.003 wt.% P, while it is the worst in the steels with * 0.3 wt.% P. This indicates that the surveillance test of HAZ specimen can be represented by base metal in the case of A533B steels with lower P content (* 0.003 wt.%). The effects of notch location and chemical contents on ductile to brittle transition temperature (DBTT) are almost independent of specimen size within an error of +5 K, indicating that the miniaturized Charpy specimens are applicable and effective in the surveillance tests of reactor pressure vessel steel of extended operation period. After irradiation, the highest DBTT was observed for the specimen with V-notch in base metal in the case of A533B steel and high Cu steel with 0.003 wt.% P.

Effect of thermal cycling induced phosphorus grain boundary segregation on embrittlement of welding heat affected zones in 2·25Cr–1Mo steel

“…Also, phosphorus grain boundary segregation induced a higher ductile to brittle transition temperature (DBTT) of post-weld heat treated heat affected zones (HAZs) located at 1 mm away from fusion boundary in a 0?3 wt-%P doped A533B steel than the undoped one. 11 As seen above, impurity grain boundary segregation can deteriorate the toughness of CGHAZs after PWHT. However, in many cases, a single pass welding without a PWHT is used in welding processes.…”

“…6,7 So far, studies on the impurity induced embrittlement of CGHAZs focus mainly on the reheat cracking or stress relief cracking of CGHAZs after a post-weld heat treatment (PWHT). [8][9][10][11] As reviewed by Dhooge et al, 9 grain boundary segregation of impurities (P, Cu, Sb, Sn and As) was found to cause an underclad cracking or reheat cracking in the CGHAZs, which had been heated twice by welding in nuclear reactor pressure vessel steels, e.g. SA508 Class 2 steel.…”

“…Also, phosphorus grain boundary segregation induced a higher ductile to brittle transition temperature (DBTT) of post-weld heat treated heat affected zones (HAZs) located at 1 mm away from fusion boundary in a 0·3 wt-P doped A533B steel than the undoped one. 11…”

Measurement of the $$^{244}$$ 244 Cm and $$^{246}$$ 246 Cm Neutron-Induced Cross Sections at the n_TOF Facility

“…The 244 Cm(n,γ) cross section data range from 20 eV to 1 keV and the 246 Cm(n,γ) data from 20 eV to 400 eV. Recently, a second measurement of both (n,γ) cross sections has been performed with a large coverage Ge array in the Accurate Neutron Nucleus Reaction Measurement Instrument ANNRI at J-PARC [3], in the energy range of 1 eV to 300 eV. The scarcity of the available data and the many experimental challenges involved in the two previous measurements makes highly desirable to perform an additional measurement under different conditions i.e., in a different facility, with different detectors and monitors and a different methodology.…”

Recent activities in the field of nuclear materials and nuclear fuels

“…Since Charpy impact properties depend on the specimen size as well as the notch location of the weld joint [13,14], the effects of specimen size, V-notch location and chemical contents on impact properties of small specimen were evaluated. Kim et al [15] were reported that the ductile to brittle transition temperature (DBTT) and the upper shelf energy of standard size specimen could be predicted from the empirical equations obtained from the sub-sized specimens. The effects of notch location and chemical contents on DBTT were almost independent of specimen size.…”