Devices for a punch test on annular notched specimens, small punch (SP) tests, and miniaturized tension tests in hot cells were developed. A micro-manipulator to handle small specimens and an electro-discharge machine (EDM) to extract miniaturized tension specimens and annular notched specimens from transmission electron microscopy (TEM) disks were also fabricated. These devices were designed and made for remote operation in hot cells. Preliminary tests to evaluate the applicability of test methods were carried out. Correlation between SP test results and tensile properties was not strong. Miniaturized tensile results were reasonably similar to the results with larger specimens. The ductile-brittle transition temperature (DBTT) by the punch test on annular notched specimens was higher than that obtained from the SP test. However, materials dependence of the DBTT was different from that measured by standard Charpy V-notch (CVN) tests. This may be due to a specimen size effect.
Irradiation embrittlement of A533B steels with low copper contents were investigated from the point of dose rate and irradiation temperature effects. Change of neutron flux in the range from -1012 to -1013 n/cm2/s (E> 1MeV) did not have a significant effect on the embrittlement. Irradiation temperature change of 1°C resulted in the transition temperature shift (ΔT41J) of about 1°C and yield stress change (Δoy) of about 0.8MPa. Factors that might affect the embrittlement of low copper steels are also discussed.
Irradiation embrittlement in a low dose region was studied for an aluminum-killed carbon steel from the point of dose rate effects. The dose rate as low as ∼5x108 n/cm2/s (E> 1MeV) caused a Charpy transition temperature shift of more than 30°C after irradiation to ∼1017n/cm2 (E>1MeV) at 240°C, while a similar amount of Charpy shift was observed after ∼1018n/cm2 (E >1MeV) at higher dose rate (∼7x1011n/cm2/s). The effect of dose rate was obvious in the annealing response on hardness. The recovery characteristics indicated that more stable defects were produced in the material irradiated at a lower dose rate.
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