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Ebihara, Kenichi; Kaburaki, Hideo; Takai, Kenichi*
Zairyo To Purosesu (CD-ROM), 27(1), P. 418, 2014/03
In order to understand the mechanism of hydrogen embrittlement, identifying the state of hydrogen trapped by defects in steels is dispensable. In the identification of the hydrogen trapping state, thermal desorption profiles of hydrogen obtained in the thermal desorption analysis of steel specimens are widely used, and need to be analyzed using the numerical model because they include the effect of the specimen size and the experimental conditions as well as the effect of defects. The prefactor of detrap rate in the model is previously used as a fitting parameter. In the presentation, the influence of specimen size on the identification of the prefactor was examined numerically. As a result, in the specimens of pure iron and martensite steels whose size is larger than 0.3 mm, the accuracy of the identification rapidly drops. In addition, according to the influence of the prefactor on the desorption profile, it is possible to identify the order of magnitude of the prefactor.
O-SiO-FeO
based slagsHigo, Tomoyuki*; Osugi, Takeshi; Saito, Noritaka*; Nakashima, Kunihiko*
no journal, ,
no abstracts in English
Onizawa, Takashi; Kikuchi, Kenji*
no journal, ,
no abstracts in English
Xu, P. G.; Hoshikawa, Akinori*; Ishigaki, Toru*; Suzuki, Tetsuya*; Akita, Koichi; Morii, Yukio*; Hayashi, Makoto*; Lutterotti, L.*
no journal, ,
Doshida, Tomoki*; Suzuki, Hiroshi*; Takai, Kenichi*; Oshima, Nagayasu*; Hirade, Tetsuya
no journal, ,
Changes in hydrogen content and lattice defect formation associated with hydrogen under elastic tensile stress of tempered martensitic steel were examined. The relationship between hydrogen embrittlement and lattice defects associated with hydrogen was also investigated. The results obtained in this study can be summarized as follows. Besides hydrogen content and applied stress, time of the formation and accumulation of vacancies was also closely involved in hydrogen embrittlement and is concluded to be an important factor causing hydrogen embrittlement.
Suzuki, Hiroshi; Akita, Koichi
no journal, ,
It has been known to be difficult to measure the residual stress near a weld accurately due to a complex microstructure in a heat affected zone. In this study, we show that the residual stress around the weld can be measured accurately in consideration of the influences of phase transformation and intergranular strains. Furthermore, it is shown that a change in residual stress due to crack propagation near the weld can be measured by the neutron diffraction technique. The neutron diffraction technique can be a complementary measurement technique with a mechanical measurement technique like strain gauges, as an important method to measure residual stresses of welded structures.
Harjo, S.; Aizawa, Kazuya; Gong, W.; Kubota, Satoru*; Tomota, Yo
no journal, ,
Hayashi, Kentaro*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro
no journal, ,
Process evaluation of use of high temperature gas-cooled reactors (HTGRs) to the ironmaking system based on active carbon recycling energy system (iACRES), where CO is recycled by reduction of CO from blast furnaces (BFs), was carried out by heat and material flow analysis. The investigated CO recovery methods were CO electrolysis and CO reduction in reverse water gas shift reaction (RWGS) using H made in the IS process. HTGR number per BF was large in the CO reduction process because more H than stoichiometric amonut was required to keep RWGS equilibrium. More CO reduction per unit ironmaking amount was expected in the CO reduction process because H not used in RWGS was consumed by iron ore reduction in the BF. However, CO reduction per HTGR was larger in the CO eelctrolysis method.
Hayashi, Kentaro*; Suzuki, Katsuki*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji
no journal, ,
Evaluation of active carbon recycling energy system for ironmaking process by modeling with Aspen Plus was carried out by CO emission and exergy consumption. The investigated CO recovery methods were CO electrolysis and CO reduction in reverse water gas shift reaction (RWGS) using H made in the HTGR-IS process. More H than stoichiometric amonut was required to keep RWGS equilibrium and H not used in RWGS was consumed by iron ore reduction in the BF. Though CO decrease was more in CO reduction process, exergy consumption was larger. CO decrease was larger in higher BFG circulation ratio and CO reduction ratio due to more carbon recycle. Exergy consumption was large in the higher reduction ratio because of more electricity consumption.