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Fukuoka-shi, Japan

Sakamoto T.,Ehime University | Kurishita H.,Tohoku University | Matsuo S.,Tohoku University | Arakawa H.,Tohoku University | And 9 more authors.
Journal of Nuclear Materials | Year: 2015

Structural materials used in radiation environments require radiation tolerance and sufficient mechanical properties in the controlled state. In order to offer SUS316L austenitic stainless steel with the assumed requirements, nanostructured SUS316L with TiC addition of 2% (SUS316L-2TiC) that is capable of exhibiting enhanced tensile ductility and flow strength sufficient for structural applications was fabricated by advanced powder metallurgical methods. The methods include MA (Mechanical Alloying), HIP (Hot Isostatic Pressing), GSMM (Grain boundary Sliding Microstructural Modification) for ductility enhancement, cold rolling at temperatures below Md (the temperature where the martensite phase occurs by plastic deformation) for phase transformation from austenite to martensite and heat treatment for reverse transformation from martensite to austenite. It is shown that the developed SUS316L-2TiC exhibits ultrafine grains with sizes of 90-270 nm, accompanied by TiC precipitates with 20-50 nm in grain interior and 70-110 nm at grain boundaries, yield strengths of 1850 to 900 MPa, tensile strengths of 1920 to 1100 MPa and uniform elongations of 0.6-21%, respectively, depending on the heat treatment temperature after rolling at -196 °C. © 2015 Elsevier B.V. Source


Hayashi M.,Kobe University | Ohya M.,Sankyu Incorporated | Sakamoto K.,Public library of Kobe City | Yamashita E.,Okayama University of Science
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2014

Water temperature decides solubility and the direction of N2O flux. When water temperature is low, solubility is high and N2O in seawater is under saturation. Water temperature also affects the volume of the flux in this situation. When water temperature is high, because solubility decreases, N2O is emitted from the sea to the air. The volume of flux is decided by N2O concentration in seawater. Water temperature is main factor for N2O exchange. Japanese coastal seas can have as both sink and source of N2O. Copyright © 2014 by the International Society of Offshore and Polar Engineers (ISOPE). Source


Yoji W.,Sankyu Incorporated | Satohiro I.,Sankyu Incorporated | Hiroshi T.,Kitakyushu National College of Technology | Tomiko Y.,Kyushu Institute of Technology | Kazumasa N.,Kyushu Institute of Technology
Welding International | Year: 2015

To minimize the volume of argon required for on-site TIG welding of titanium plate, we investigated the behaviour of argon flow in a trailing-shielding box by means of computational fluid dynamics (CFD) simulations. In this study, we designed a model of a solid rectangular shielding box consisting of 9.5 × 105 tetrahedral elements. Then, argon flow was simulated for various shielding parameters, namely the gap between the box and floor and the argon supply rate. In an experiment using dry ice mist to visualize the flow of argon, we investigated the flow from a shielding box model consisting of acrylic plates for various shielding parameters. In this manner, we studied the relation between the oxygen content in the shielding box and the shielding parameters. Then, a conventional shielding box and a prototype shielding box were evaluated experimentally. We confirmed the relation between the oxygen content in the shielding boxes and the degree of oxidation on the bead surface in TIG arc melt-run welding of titanium plate. The experimental results show that the simulation model used in the CFD simulations allowed the behaviour of argon to be predicted. We conclude that the simulation model is useful for improving the structure of the shielding box. © 2013, © 2013 Taylor & Francis. Source


Yoshimoto T.,Sankyu Incorporated | Horikawa H.,Sankyu Incorporated | Sugioka T.,Sankyu Incorporated | Wada Y.,Sankyu Incorporated | And 2 more authors.
Welding in the World | Year: 2013

Various kinds of austenitic stainless steel have been used in oil refineries and chemical plants, and a value of ultrasonic wave velocity is necessary for not only thickness measurement but also evaluation of material deterioration. Although ultrasonic wave velocity depends generally on chemical composition, material structure, grain size, etc., it is hard to study the influence of all factors for calculating ultrasonic wave velocity. Therefore, we noticed chemical composition of materials only. Since ultrasonic wave velocity depends generally on parameters such as density ρ, Young's modulus E, and Poisson's ratio ν, we calculated these parameters by using material data of respective elementary substances. Then, we have investigated the relationship between the calculated values of ultrasonic wave velocity and the experimental ones measured by ultrasonic testing. © 2013 International Institute of Welding. Source


Wada Y.,Sankyu Incorporated | Inoue S.,Sankyu Incorporated | Tsukamoto H.,Sankyu Incorporated | Yamaguchi T.,Sankyu Incorporated | Nishio K.,Sankyu Incorporated
Science and Technology of Welding and Joining | Year: 2012

To minimise the volume of argon required for on-site tungsten inert gas welding of titanium plate, the authors investigated the behaviour of argon flow in a trailing-shielding box by means of computational fluid dynamics (CFD) simulations. In this study, a solid rectangular shielding box consisting of 9·5×10 5 tetrahedral elements was modelled. Then, argon flow was simulated for two shielding parameters, namely, the argon supply rate and the gap between the box and the floor. In the experiment, the relation between the oxygen content in the shielding box and the shielding parameters was studied. The experimental results show that the simulation model used in the CFD simulations can predict the behaviour of argon. It is concluded that the simulation model is useful for improving the structure of the shielding box. © 2012 2012 Institute of Materials, Minerals and Mining. Source

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