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Takaishi, Japan

Okayasu M.,Akita Prefectural University | Yoshie S.,Osaka Fuji Corporation
Materials Science and Engineering A | Year: 2010

Examination of the mechanical properties of cast aluminum alloys (AC8A: Al-Si13-Ni1.4-Mg1.4-Cu1), created by the Ohno continuous casting (OCC) process, was conducted. The material strength and ductility of the OCC samples are twice as high as the same aluminum alloy produced by conventional gravity casting. The increase of material strength of the OCC sample is attributed to (i) tiny spherical α-Al grains, (ii) fewer cast defects and (iii) solid-solution strengthening by silicon. The high material ductility of the OCC sample is related to the regularly oriented crystal structure, where the crystal direction (111) in the cast sample is perpendicular to the casting direction, and (110) and (100) directions can be detected in the longitudinal direction of the sample. The yield stress of the OCC sample can be estimated by two different parameters: solid-solution strengthening, k√c, and grain size, ky/√d (Hall-Petch relation). © 2010 Elsevier B.V. Source


Okayasu M.,Akita Prefectural University | Takasu S.,Akita Prefectural University | Yoshie S.,Osaka Fuji Corporation
Journal of Materials Processing Technology | Year: 2010

The specific objective in this work is an exploration of the material properties produced by a recently developed continuous casting technique. The study focuses on an Al-Cu alloy provided by the Ohno continuous casting process. The experimental approaches give rise to unusual microstructural characteristic in the cast samples, namely a fine lamellar eutectic structure with unidirectional growth along its axial direction together with a regularly oriented lattice structure. Such microstructural characteristics significantly increase the tensile and fatigue properties. © 2010 Elsevier B.V. Source


Sudiro T.,Hokkaido University | Sano T.,Hokkaido University | Kyo S.,Kansai Electric Power Co. | Ishibashi O.,Osaka Fuji Corporation | And 2 more authors.
Materials Transactions | Year: 2011

The addition of Si to CoNiCrAlY was considered in order to develop corrosion resistant alloys for coating applications. The high temperature corrosion behavior of spark plasma sintered CoNiCrAlY alloys of 0, 10, 20, and 30 mass% Si content was investigated in an air(Na 2SO 4+25.7 mass%NaCl) gas atmosphere at elevated temperatures of 923, 1073, and 1273 K. The results showed that CoNiCrAlY-Si alloys formed mainly an Al 2O 3 or Al 2O 3/SiO 2 scale, depending on the alloy composition and the temperature. The addition of 30% Si significantly improved the high-temperature corrosion resistance of CoNiCrAlY alloy in an air-(Na 2SO 4+25.7 mass%NaCl) gas atmosphere at these temperatures. The high temperature corrosion behavior of CoNiCrAlY-Si alloys was discussed in the present paper. ©2011 The Japan Institute of Metals. Source


Sudiro T.,Hokkaido University | Sano T.,Hokkaido University | Sano T.,Mitsubishi Group | Kyo S.,Kansai Electric Power Co. | And 3 more authors.
Materials Transactions | Year: 2012

In this study, an attempt has been made to improve the resistance of CrSi 2 alloy toward high temperature corrosion and promote the formation of a continuous and slow-growing SiO 2 scale on the alloy surface. For this purpose, spark plasma sintering was used to fabricate the CrSi 2 alloys containing various amounts of CoNiCrAlY. The sintered alloys were then corroded isothermally in an airNa 2SO 4NaCl gas atmosphere at three different temperatures of 923 and 1073K for up to 720 ks and at 1273K for 72 ks. XRD, SEM and SEM-EDS were utilized to examine the alloy structures and compositions before and after the high temperature corrosion test. The influence of CoNiCrAlY addition on the high temperature corrosion behavior of the CrSi 2 alloy was clarified. © 2012 The Japan Institute of Metals. Source


Motoyasu G.,Chiba Institute of Technology | Yamazaki H.,Osaka University | Yamazaki H.,Osaka Fuji Corporation | Ohno A.,Chiba Institute of Technology | And 2 more authors.
Journal of Materials Engineering and Performance | Year: 2015

Throughout a long and distinguished career, the research activities conducted by Professor Ravindran have been characterized by the quest to generate fundamental as well as practical knowledge through collaborative efforts involving academia and industry as a basis for development of innovative manufacturing routes and improvement in performance of existing products and processes based on near-net-shape casting technologies. In this paper, the generation, validation, and implementation of new knowledge is illustrated by the Ohno Continuous Casting process, a heated mold system that permits the production of net-shape or near-net-shape products with a high-quality surface, controlled solidification structure, and significantly enhanced properties. © 2015, ASM International. Source

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