Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Iwata, Mitsunao*; Sugiyama, Yuichi*; Murata, Yoshinori*; Takaya, Shigeru
Defect and Diffusion Forum, 326-328, p.578 - 582, 2012/04
Times Cited Count：0 Percentile：0.01(Nanoscience & Nanotechnology)no abstracts in English
Sugiyama, Yuichi*; Iwata, Mitsunao*; Murata, Yoshinori*; Takaya, Shigeru
no journal, ,
no abstracts in English
Sugiyama, Yuichi*; Iwata, Mitsunao*; Murata, Yoshinori*; Takaya, Shigeru
no journal, ,
no abstracts in English
Iwata, Mitsunao*; Sugiyama, Yuichi*; Murata, Yoshinori*; Takaya, Shigeru
no journal, ,
Microstructural states of metallic materials can be expressed by system free energy, and the estimation of the system free energy is useful for damage analysis of the materials. In this study, change with creep time in the system free energy of the FG-HAZ in 9Cr heat resistant ferritic steels is estimated on the basis of a series of experiments such as chemical analysis by using extracted residues, X-ray diffraction, and scanning transmission observations. The change in the system free energy is expressed quantitatively by rate constants depending on applied stress. It is observed that the steel ruptures when the applied stress exceeds the allowable stress. The relationship between allowable stress and system free energy makes it possible to predict the rupture time in the long term.
Fujii, Shohei*; Iwata, Mitsunao*; Murata, Yoshinori*; Takaya, Shigeru
no journal, ,
It is necessary to maintain the integrity of structural materials including welded parts for long term for fast breeder reactors. It is known that long-term creep strength of heat affected zone (HAZ) of 9Cr ferritic steels decreases because of change in micro structure. Therefore, it is very important to develop a method to estimate long-term strength from short-term material test results. In this study, we evaluated system free energy of creep test pieces of simulated HAZ material. As result, we have shown that system free energy decreases with time, and the decrease rate depends on load stress. Furthermore, we proposed a new parameter, P, which indicates the rate of decrease of system free energy, and have shown that it is able to evaluate long-term creep strength based on the relationship between load stress and P.
