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Volume 69, Issue 12
Displaying 1-10 of 10 articles from this issue
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Motonori Tamura, Koji Shibata2005 Volume 69 Issue 12 Pages 1039-1048
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSMechanical properties of candidate materials for hydrogen container were studied in high pressure of gaseous hydrogen by using newly designed and installed facilities. Tensile properties, slow strain rate tensile properties, fatigue properties and fatigue crack growth properties of aluminum alloy AA6061-T6 and austenitic stainless steel of type 316L in 45 MPa gaseous hydrogen were similar to those properties tested in air. These data can give guideline not only to the reference standard and technical standard dealing with 35 MPa-class compressed hydrogen container but to future material development of various apparatuses for hydrogen.
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Nobuhisa Ishiyama, Masami Mayuzumi, Yoshihiro Mizutani, Junichi Tani2005 Volume 69 Issue 12 Pages 1049-1052
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSRecently, stress corrosion cracking (SCC) was observed in lots of Japanese BWR components made of L grade stainless steels (SS) with very low carbon content. SCC of L grade SS is quite different from the conventional IGSCC of SUS 304 SS since no sensitization is observed in the cracked region. Hence, the purpose of this study is to determine the material condition which is the most susceptible to such type of SCC. The SCC test was conducted by the creviced bent beam (CBB) method in high temperature water containing 8 ppm dissolved oxygen. The test specimen was cold rolled and/or heat treated at a temperature range from 873 K to 1073 K. The maximum SCC susceptibility was obtained in the as-received condition with cold rolling ratio of 10% for both SUS 316L and SUS 316 SS. The fracture surface consisted of mainly intergranular SCC with a small fraction of transgranular SCC similar to those observed in the actual components of BWR.
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Atsushi Nakano, Kouko Takesako, Kosaku Yamada, Hidekazu Sueyoshi2005 Volume 69 Issue 12 Pages 1053-1056
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSInventory analysis of manufacturing system for both former Pb-free bronze made from virgin materials and new Pb-free bronze made by removing Pb from scrap Pb-bronze was assessed from the view point of life cycle assessment (LCA). The result shows that new manufacturing system of Pb-free bronze made by removing Pb from scrap Pb-bronze reduces such environmental impacts as global warming, acidification, energy consumption, resource consumption significantly. Thus, in LCA perspective, the new manufacturing system using a recycling Pb-free bronze is superior to the former one using virgin materials.
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Yoshitaka Misaka, Kazuhiro Kawasaki, Jun Komotori, Masao Shimizu2005 Volume 69 Issue 12 Pages 1057-1063
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSTo clarify the effects of Super Rapid Induction Heating and Quenching (SRIHQ) on fatigue properties of Ferritic Ductile Cast Iron (FDI), rotational bending fatigue tests were carried out on specimens treated with four types of heating cycle. Results showed that; (i) the SRIHQ process generated a thin dark gray area around the graphite. This dark area was composed of a martensite structure (ringed martensite). (ii) The ringed martensite generated a compressive residual stress field at the surface hardened layer. Two types of compressive residual stress generative mechanisms were observed. One was a microscopic residual stress generative process due to the formation of ringed martensite and the other was a macroscopic residual stress generative process due to the expansion of the surface hardened layer. (iii) The fatigue strength of SRIHQ treated FDI specimen was higher than that of the untreated one. This was because the compressive residual stress field generated by the ringed martensite suppressed initiation and propagation of fatigue cracks.
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Kazunori Tanaka, Yoshitake Nishi2005 Volume 69 Issue 12 Pages 1064-1068
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSBy using a complex-coated carbon fiber felt constructed with nickel interlayer and aluminum surface skin, copper welding to aluminum is successfully developed. The first step of the welding method is that the felt is contacted and wrapped with molten aluminum, which is solidified under gravity pressure. The second step is that the aluminum-welded felt is contacted and wrapped with a molten copper, which is solidified under gravity pressure. The carbon fiber junction device is a fiber reinforced alloy and acts as an ideal joining part of copper and aluminum. Tensile strength of the junction device of carbon fiber reinforced Cu-25 at%Al alloy is higher than those of a Cu-25 at%Al alloy and an aluminum rod.
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Masahiro Kitada2005 Volume 69 Issue 12 Pages 1069-1076
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSThe microstructures and physical properties of Niiro-colored Cu-4 mass%Au alloy (shakudou in Japanese) have been investigated. Specimens are fabricated by using a traditional Japanese metal-craft technique. An aqueous solution containing cupric sulfate, alum and artificial verdigris is used to color the alloy sheets. Coloring is performed at 373 K(100°C). The fine structures are observed using a transmission electron microscope. The matrix of the colored layer consists of crystalline and amorphous Cu2O and the crystal size is 30~80 nm. The relation Cu2O{111}//Cu-Au{111} is observed between the grown Cu2O and the matrix Cu-Au alloy. The Au fine particles with 2-5 nm diameters are distributed in the Cu2O layer. Many impurities of Cl and S introduced from the coloring solution are detected from the top of the colored layer by AES analysis. The reflectance of the colored specimen is approximately 5% of the uncolored alloy and a broad reflection peak near 450 nm is observed. The threshold voltage of Cu2O/Cu-Au alloy contact for the colored specimen is 0.2-0.3 V. This is approximately 1/3 of that of thermally oxidized Cu2O /Cu-Au alloy contact. The coloring is mainly due to light absorption and reflection by the fine Au particles distributed in the Cu2O layer.
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Yasunori Miyata, Takayuki Satoh2005 Volume 69 Issue 12 Pages 1077-1083
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSSolidification Morphology in highly supercooled melt was observed and characteristics studied. High supercooling was performed using a Peltier module that locally cooled the melt of organic material, succinonitrile, near the wall of specimen cell, resulting in rapid solidification at that site. Small dendrites solidified together, showing them predominant in highly supercooled melt. Growth rate of dendrites was demonstrated to have similar dependency on supercooling as that of free dendrites.
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Hitoshi Nagayama, Hidehiro Yoshida, Yuichi Ikuhara, Taketo Sakuma2005 Volume 69 Issue 12 Pages 1084-1088
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSSuperplastic flow behavior in 1 mol%GeO2 and 1 mol%NdO1.5 co-doped tetragonal ZrO2-3 mol%Y2O3 polycrystal (3Y-TZP) was examined at 1400°C under an initial strain rate of 1.3×10-4 s-1. 1 mol%GeO2 or NdO1.5-doping slightly enhances high-temperature ductility in 3Y-TZP, but 1 mol%GeO2 and 1 mol%NdO1.5 co-doped TZP exhibits large elongation to failure of more than 600%. The large ductility in TZP due to Ge4+ and Nd3+ co-doping can be explained by reduced flow stress. High-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDS) analysis revealed that Y3+, Ge4+ and Nd3+ cations segregate in the vicinity of grain boundaries in the present materials. The segregation width of the dopant cation across the grain boundaries in GeO2 and NdO1.5 co-doped TZP is larger than that in GeO2 or NdO1.5 singly doped TZP. The reduction of the flow stress due to GeO2 and NdO1.5 co-doping is probably related to the increment in the segregation width.
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Kazuyuki Ogawa, Setsuo Kajiwara2005 Volume 69 Issue 12 Pages 1089-1098
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSThe present work aims to clarify the atomic arrangements at the austenite/martensite interfaces for the nucleating martensite and the edge of growing martensite. The Fe-23Ni-3.8Mn alloy and the Fe-9Cr-1.1C alloy with the K-S orientational relationship with the {112} habit plane were observed with the high resolution electron microscopy. At the very tip of wedge-shaped growing martensite, dislocations queues up on every about six (111)f layers along the interface, with their extra-half plane in the austenite. The nucleus of the martensite was observed in the Fe-9Cr-1.1C alloy. The nucleus has the K-S orientational relationship with a habit plane of (111)f(//(011)b) and an wing-like shape, and remarkably expands in the direction of [101]f(//[111]b). The crystal structure of the nucleus shows a lattice transition region from fcc to bct toward inside, and the transformation into the final martensite structure (bct) is still incomplete even at the center of the nucleus.
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Toshiharu Kobayashi, Hiroshi Harada, Makoto Osawa, Atsushi Sato2005 Volume 69 Issue 12 Pages 1099-1103
Published: 2005
Released on J-STAGE: December 20, 2005
JOURNAL FREE ACCESSOur Ni-base single crystal (SC) superalloys that have been designated as 4th and 5th generation SC alloys contain Ru for the enhancement of microstructure stability. The authors have previously reported that Ir addition was as effective as Ru for enhancing the microstructure stability.
In this paper, Ir was added to TMS-173, a new 5th generation SC alloy, by substituting out Ru. The creep strength of this new SC alloy, designated as TMS-173(Ir), was then compared to that of the original Ru-containing alloys, TMS-173. Creep tests were conducted for these SC superalloys under several conditions: 800°C/735 MPa, 900°C/392 MPa, 1000°C/245 MPa and 1100°C/137 MPa. The Ir-containing alloys showed shorter creep rupture life than The Ru-containing one in higher temperature and lower stress conditions such as 1100°C/137 MPa. However, at lower temperature and higher stress conditions, The Ir-containing alloy showed longer creep rupture life than Ru-containing one; the former showed 3.2 times longer creep rupture life than the latter in the creep tests at 900°C/392 MPa. Microstructure observations of creep-ruptured specimens confirmed that Ir was as effective as Ru for microstructure stability.
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