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Momma, Yoshio*; *; ; ; ; Aoto, Kazumi
JNC TN9400 2000-044, 22 Pages, 2000/03
JNC-TN9400-2000-044.pdf:1.37MB
ln the past the microstructural observation was mostly applied to understand the materials behavior qualitatively in R&D of the new materials and the life prediction for the fast breeder reactor components. However, the correlation between the changes in properties and microstrutures must be clarified to ensure the structural integrity. Particularly we are interested in the method to correlate the long-term properties and microstructural changes at high temperatures. The current research is to quantify the changes in microstructure of the weld metal for the welded structure of the reactor vessel. ln this research we have conducted creep testing of the weld metals at 823 and 873K up to 37,000h. Two types of the weld metals (16Cr-8Ni-2Mo and 18Cr-12Ni-Mo) were subjected to the creep testing. Based on the areas of the precipitates, the microstructural characterization with time and creep damage was attempted. The creep strength of the 16Cr-8Ni-2Mo weld metal is lower than that of the 18Cr-12Ni-Mo one at higher stresses, shorter times. But there is a trend toward to become similar strength with lower stresses and increasing times. The creep-rupture ductility of the 16Cr-8Ni-2Mo weld metal is superior to that of the 18Cr-12Ni-Mo one. The creep-rupture takes place at the interface of the sigma (
) phases precipitated in the delta (
) ferrites at 823K lower stresses and 873K. The amount of precipitates in the 16Cr-8Ni-2Mo weld metal is smaller than that in the 18Cr-12Ni-Mo one at each temperature and stress. Also it is apparent that the amount of the precipitates is primarily responsible to the decomposition of the phase, because the amount of the residual ferrites measured by the Magne-Gauge reduces with times. Using the Larson-Miller parameter it was possible to correlate the amount of the precipitates linearly with the LMP values.
; *; Seki, Masayuki; Tobita, Noriyuki; Nagai, Shuichiro; ;
PNC TN8410 91-221, 67 Pages, 1991/08
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Tsutagi, Koichi; Seki, Masayuki; Tobita, Noriyuki; Nagai, Shuichiro; ; *; *
PNC TN8410 91-256, 64 Pages, 1991/05
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Tsutagi, Koichi; Seki, Masayuki; Tobita, Noriyuki; ; *; *
PNC TN8410 91-174, 40 Pages, 1991/02
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*
PNC TN9410 90-054, 125 Pages, 1990/01
A preliminary analysis was performed on the sodium thermal fatigue tests which are planned to be conducted with the "Sodium Thermal Fatigue Test Apparatus", which was recently constructed in the material development section. This test machine was constructed for the purpose of aquisition of data needed for sofistication of the evaluation method of creep-fatigue and crack propagation of welded joints. This preliminary analysis is concerned with thermal analysis and stress analysis on test specimens which are planed to be used in the machine. Effects of following parameters on temperature/stress distribution of test specimens under various conditions were analysed. Thcse parameters are considered to play significant roles in the analysis of the results of upcoming experiments. (1)Heat transfer coefficient (2)Thermal shock temperature (3)Speed of submerging specimen (4)Comparison of behavior of base metal and welded joint (5)Comparison of mechanical loading and thermal loading