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Volume 62, Issue 3
Displaying 1-12 of 12 articles from this issue
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Hideo Saito, Kun’ichi Miyazawa, Minoru Mori1998 Volume 62 Issue 3 Pages 215-223
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSBehavior of hydrogen accumulation in a long-term aged of austenitic stainless steel SUS316 was investigated by tritium transmission electron microscopic (TEM) autoradiography. The thin foil specimens were exposed either immediately after the electrolytic charging of tritium at 253 K (diffusing tritium) or after hold at the room temperature for three days (non-diffusing tritium). Tritium TEM autoradiographs were observed by changing the inclination of the specimen. Chromium carbide (Cr23C6) was precipitated along the grain boundary and within the matrix. Blackened silver particles of large number were observed around the chromium carbide (Cr23C6) and its circumference.
On the other hand, tritium TEM autoradiographs of the specimen held at room temperature for three days were revealed at the noncoherent interfaces of chromium carbide (Cr23C6) precipitated along the grain boundary and within the matrix. But they were not observed at better coherent interfaces of chromium carbide (Cr23C6). The amount of diffusing hydrogen were about seven times larger compared with those of non-diffusing hydrogen.View full abstractDownload PDF (1604K) -
Norio Maruyama, Kozo Nakazawa, Masae Sumita, Mitsunori Sato1998 Volume 62 Issue 3 Pages 224-231
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA study has been made of the effects of mechanical properties of the matrix and the amount of SiC particles on fatigue strength and fretting fatigue strength using 2024-T6 heat treated (T6) and 2024-O heat treated (O) Al alloy metal matrix composites reinforced with 10, 20 and 25 vol%SiC particles with the mean size of 2 μm.
The 107 cycles plain fatigue and fretting fatigue strengths of the T6-composites increased but then decreased with an increase in the amount of SiC, having a maximum value at about 20%, while those of the O-composites increased with an increase in the amount of SiC up to 25%.
The 107 cycles plain fatigue strengths of the T6- and O-composites were nearly equal to those estimated on the basis of the change of the elastic modulus and the ultimate tensile strength due to the reinforcement.
The 107 cycles fretting fatigue strengths of the T6- and O-composites were higher and lower, respectively, than the estimated ones.View full abstractDownload PDF (778K) -
Kazuaki Sanada, Yasuhide Shindo, Katsumi Horiguchi, Hitoshi Tokairin1998 Volume 62 Issue 3 Pages 232-237
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe object of this study is to investigate the size effect and cryogenic fracture characteristics of G-11 woven glass-epoxy laminates. Fracture toughness tests were carried out with compact tension (CT) specimens at room temperature and 77 K. CT specimens with different widths and thicknesses were tested in accordance with ASTM E399-83, ASTM E813-89 and JSME S001. The results showed that the apparent fracture toughness are strongly influenced by specimen size. The damage morphology around the notch tip of tested specimens was characterized using a microscope. The damage occurred with increasing applied load, and the interaction of the damage zone and the size effect in fracture was exhibited.View full abstractDownload PDF (672K) -
Kuniteru Mihara, Takao Takeuchi, Hirowo G. Suzuki1998 Volume 62 Issue 3 Pages 238-245
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe need for the development of the conductive materials with high conductivity and high strength is increasing to a large extent. In the previous studies, it was shown that the Cu-Cr in-situ composite has demonstrated excellent mechanical and electrical properties. The aim of the present study is to further strengthen this composite by adding a third element. In this work, Zr is selected as an alloying element because it has capacity for enhancing the precipitation hardening of the alloy.
The authors prepared Cu-15 mass%Cr-0.15 mass%Zr alloy and investigated its solidification structure, cold worked structure, and aging characteristics as follows.
(1) A band structure and heavily deformed structure exist in the Cu phase due to the accumulation of drawing strain.
(2) The specimens aged between 623 and 723 K surpass those of the as-rolled specimens with regard to 0.2 PS and σB.
(3) The TEM observation showed that three types of precipitates exist after aging. i.e., precipitates on vacancies, dislocations and grain boundaries. The precipitates on dislocations contribute to the secondary hardening.View full abstractDownload PDF (1426K) -
Kouichi Kawahara, Sadahiro Tsurekawa, Hideharu Nakashima1998 Volume 62 Issue 3 Pages 246-254
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn order to clarify the effects of sintering aids (B+C) on high temperature deformation behaviour of β-SiC, HIPed β-SiC without sintering aids and pressureless sintered β-SiC with B and C addition were subjected to compression tests at temperatures from 2170 to 2270 K and at strain rates from 6×10−6 to 2×10−5 s−1. In addition, dislocation structure developed during deformation was analyzed by transmission electron microscopy (TEM). It was found that the flow stress of β-SiC without sintering aids was ca. twice as much as that of the B+C added one. The appearance of the stress-strain curves was noticeably different between them: while the steady state was observed on the stress-strain curves for β-SiC without additives, the flow stress oscillation was observed, followed by yield drop for B+C added ones. TEM observations revealed that dislocations in B+C added β-SiC were dissociated into the Shockley partial dislocations with much larger width than dislocations in β-SiC without additives. This observation suggested that the addition of B+C would probably reduce the stacking fault energy. The observed differences in deformation behaviour will be discussed from the viewpoints of differences in the magnitude of the stacking fault energy and in the mobility of two partial dislocations.View full abstractDownload PDF (2008K) -
Satoshi Hashimoto, Hiroyuki Miyamoto, Takuro Mimaki1998 Volume 62 Issue 3 Pages 255-260
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe aim of the present study is to obtain a fundamental knowledge about sliding characteristics along the austenite(γ)/ferrite(α)-interphase boundary which may play a variety of roles in high temperatures and superplastic deformations of a two-phase(γ⁄α) stainless steel. Sliding of the interphase boundary has been studied by a simple shear test under constant loads at 1373 K, employing bicrystals with the (γ⁄α)-interphase boundary produced by a solid-solid diffusion method. The experimental results could be analyzed through the power law of v∝τn, where V is the sliding velocity and τ is the shear stress. The value of n was estimated to be approximately 2. Local plastic deformation in the α-phase and no plastic deformation in the γ-phase neighboring to the interphase were observed. Metallograpy after the sliding test showed that no recrystallization occurred in the α-phase neighboring to the interphase-boundary. Appreciable void formation was observed along the slid interface. Furthermore, the activation energy of the sliding was estimated to be close to that of the bulk self-diffusion in α-phase. These facts suggest that the behavior of interphase-boundary sliding is closely associated with ductile deformation of a thin layer of the α-phase in the immediate vicinity to the interface, rate-controlled by climb motions of dislocations arrested along the interphase-boundary.View full abstractDownload PDF (1121K) -
Residual Stress Measurements by X-ray and Neutron Diffractions in Heat-Treated SiCw/A2014 CompositesTakahisa Ohnuki, Motoo Fujita, Yo Tomota, Masayoshi Ono1998 Volume 62 Issue 3 Pages 261-266
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSResidual stresses due to various heat treatments in a 22 volume percent SiC whisker/A2014 metal matrix composite (MMC) were measured by using X-ray and neutron diffractions. Micro residual stresses generated from the differences in thermal expansion coefficients of the constituents and macro residual stresses associated with different cooling rates in the outer and inner regions of an MMC specimen must be distinguished in X-ray stress measurements. The conventional sin2ψ method under an assumption of plane stress condition has been found not to be applicable to the present MMC, because interactions among whiskers in the X-ray penetrating area yields σ33 where the x3-axis is normal with respect to specimen’s surface. An average value of σ33 can be measured by X-ray diffraction technique, but does not seem enough to evaluate micro residual stresses. It is found that neutron diffraction is the most powerful method to measure micro residual stresses in the constituents. Elastic residual strains obtained by neutron diffraction in solution treated or T6 heat treated samples show good agreements with predictions calculated by using Eshelby inclusion theory coupled with the Mori-Tanaka mean field concept, indicating that the influence of stress relaxation is negligible. In addition, internal stresses relaxations during holding at room temperature, slow cooling from solution treatment temperature, or subzero cooling are discussed.View full abstractDownload PDF (604K) -
Kenichi Takai, Goro Yamauchi, Mariko Nakamura, Michihiko Nagumo1998 Volume 62 Issue 3 Pages 267-275
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSHydrogen absorption characteristics of pure iron and eutectoid steel fabricated by cold drawing have been evaluated by thermal desorption spectrometry (TDS). The pure iron specimens with ferrite (α) structure and the eutectoid steel specimens with α and Fe3C structures, were produced under various degrees of reduction and also under various heat treatment conditions. These amount of hydrogen absorbed in specimens dipped in 20 mass%NH4SCN solution were measured using TDS. TDS analysis showed that hydrogen evolution rate of pure iron has only one peak, while that of eutectoid steel has two peaks. From transmission electron microscopy and TDS analysis, the lower temperature peak was attributed to hydrogen released from the trapping sites such as point defects, clustered defects, and dislocations in α. The higher temperature peak was found to correspond to hydrogen released from the trapping sites such as defects in Fe3C, and/or such as the disordered interface between α and Fe3C.View full abstractDownload PDF (1813K) -
Eiji Tada, Kazuhiko Noda, Shinji Kumai, Tooru Tsuru1998 Volume 62 Issue 3 Pages 276-282
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCorrosion fatigue tests of a commercial iron with a hole were carried out in a borate buffer solution containing 5 mol/m3 NaCl at a constant passive potential. Polarization current behavior induced by strain cycles has been investigated in order to detect crack initiation from the hole and used for the estimation of corrosion fatigue damages. The amplitude of the polarization current synchronized with the strain cycle and the phase shift between the polarization current and the strain were calculated from the polarization current behavior. The second harmonics component of the polarization current was also calculated. In the early stage of the corrosion fatigue test, the phase shift was almost constant and the second harmonics component was not detected. However, the phase shift decreased and the second harmonics component of the polarization current increased with increasing fatigue cycle. It is considered that changes of the phase shift and the second harmonics component of the polarization current result from crack initiation and the early stage of crack propagation from the hole.View full abstractDownload PDF (695K) -
Hiroshi Ono, Tokuo Shimizu, Yoshio Shijo1998 Volume 62 Issue 3 Pages 283-288
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe separation and simultaneous determination of trace amounts of Fe, Cu, Zn, Ga, Mo, Cd, In and Sn in Ni were studied. After the sample was dissolved in a mixture of hydrochloric acid and nitric acid, Fe, Cu, Zn, Ga, Mo, Cd, In and Sn were separated from Ni by adsorption on an anion exchange resin column as their chloro complexes in hydrochloric acid media, and then eluted with nitric acid, followed by determination with ICP-AES and ICP-MS. Fe, Cu, Zn, Ga, Mo, Cd, In and Sn were quantitatively recovered throughout the adsorption on a column (φ, 15 mm) packed with 7.5 g of anion exchange resin in 5 mol·dm−3 hydrochloric acid and the elution with 40 cm3 of 2 mol·dm−3 nitric acid. Whereas, Ni was little recovered by the proposed method. The detection limits (μg·g−1) of each element with the proposed method by ICP-AES (ICP-MS) were found to be 1.66 for Fe, 0.056 for Cu, 7.95(0.21) for Zn, 0.034(0.013) for Ga, 0.45(0.021) for Mo, 0.043(0.033) for Cd, 0.69(0.004) for In and 1.53(0.60) for Sn using 1.0 g of Ni sample. The proposed method was applied to an analysis of the reference material, the results agreed with the certified values.View full abstractDownload PDF (490K) -
Shinji Itoh, Ryosuke Hasegawa1998 Volume 62 Issue 3 Pages 289-292
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSGlow discharge mass spectrometric (GDMS) analysis of isotopic compositions of pure boron and silicon has been studied by using a VG9000 instrument and a small quantity sample. A disk sample was prepared by pressurizing the mixture of metallic boron (or silicon) and 1.0 g of gallium with 39 MPa (400 kg/cm2). Optimum ratio of mixing of the sample and the gallium binder was examined. Increasing the sample content of the mixture caused a counting error due to the dead time of a Daly detector, which was estimated to be 0.014 μs for an integration time of 200 ms. Observed isotopic compositions of metallic boron powder and silicon thin film showed good agreement with the natural abundance or estimated values. The relative standard deviation (RSD) of repetitive five measurements was less than 0.5% for the analytical values of the isotopic compositions.View full abstractDownload PDF (358K) -
Emiko Nishimura, Yoshimitsu Okazaki1998 Volume 62 Issue 3 Pages 293-300
Published: 1998
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe trace amounts of Ti, Al and V in physiological saline solution was simultaneously determined by Inductively Coupled Plasma-Mass Spectrometry. The Al concentration was high in pyrex standard flasks as compared with those of perfluoro alkoxy alkane (PFA) and poly -4- methylpentene-1 (PMP) standard flasks. Also, Ti and V concentrations increased with small amounts of sulfuric acid and hydrochloric acid solutions, while small amounts of nitric acid solution exhibited a negligible effect on the determination of Ti, Al and V concentrations. The Ti determination measured with the isotopes of 46Ti, 47Ti and 48Ti in the Eagle’s medium was high as compared with those with the isotopes of 49Ti and 50Ti. The change in intensity with 0.5 mass ppb indium as the internal standard was small in Eagle’s medium and α-medium solutions. The intensity of 0.5 mass ppb cobalt internal standard increased with increasing α-medium solution but remained the same for the Eagle’s medium solution. The simultaneous determination of Ti, Al and V concentrations at approximately more than 1 mass ppb was possible by directly diluting Eagle’s medium and α-medium solutions 5 to 50 times.View full abstractDownload PDF (506K)
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