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Volume 54, Issue 3
Displaying 1-16 of 16 articles from this issue
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Akira Tohyama, Takemi Yamada, Yuko Hirohata, Toshirou Yamashina1990 Volume 54 Issue 3 Pages 247-254
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo keep abreast of the exceptionally rapid advances of leading industries, technologies need to be developed for an Extreme-High Vacuum (XHV) process. Because of its outstanding corrosion resistance, strength, and outgassing characteristics, SUS304(L) and 316(L) stainless steel are used for ultra-high vacuum equipments. Also, electropolishing technique has been adopted by industries because it makes the surface roughness as small as possible by minimizing the actual areas. This is a future trend of XHV equipment. The outgassing characteristics of the electropolished surface of stainless steel and effects of gas contents and inclusions of steel itself on the outgassing rate controlled by diffusion have been studied. SUS316L stainless steels, which have various contents of gas and the amounts of nonmetallic inclusions, have been melted in various conditions and rolled to plates. The sample of 8 mm×8 mm×1 mm were prepared from these plates, and all surfaces were finally electropolished. The amounts of outgassing gas by thermal desorption and the outgassing rate of H2, H2O, CO, CO2 after baked at 1123 K in a vacuum of 10−7 Pa were measured by a quadruple mass spectrometer. The molecular amount of H2 of all the samples was larger by 10 to 102 times, than those of H2O, CO, CO2 and there was no correlation between the H2 molecular amounts of outgassing by heating and the H2 content in steel. But the outgassing rate of H2 was reduced with decreasing both the H2 content and the amounts of nonmetallic inclusions. Especially, the outgassing rate of H2 was attributed to the inclusions because the hydrogen was found to be entrapped by them on the electropolished surface. Clean steel which has been produced in special cleaned melt, showed 2 orders of magnitude lower in rate than normal steel. The outgassing rates of CO and CO2 were reduced with decreasing C content in steel.View full abstractDownload PDF (1442K) -
Tae Hwan Noh, Akihisa Inoue, Hiroyasu Fujimori, Tsuyoshi Masumoto1990 Volume 54 Issue 3 Pages 255-261
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe changes in reversible enthalpy relaxation (ΔHendo) and Curie temperature (ΔTc) upon annealing were examined calorimetrically for an amorphous Fe33Ni50P17 alloy, with the aim of clarifying further the mechanism of the two-stage relaxation proposed recently for amorphous alloys. The annealed Fe-Ni-P alloy exhibited a typical two-stage enthalpy relaxation behavior. That is, a clearly distinctive two-stage splitting with maxima at about Tg-200 K and Tg was observed in the change of ΔHendo with annealing temperature. The activation energy for relaxation increases from 0.19 to 0.30 aJ for the first-stage relaxation at the lower temperature to 0.35 to 0.51 aJ for the second-stage relaxation, accompanied by a rapid increase of the frequency term. The ΔHendo increases almost linearly with ΔTc at the first-stage while no appreciable correspondence is observed at the second stage, indicating the existence of a similar mechanism for the changes of ΔHendo and Tc in the first-stage relaxation. From these results, it was interpreted that the first-stage enthalpy relaxation and the change in Curie temperature are due to the development of the chemical short-range ordering resulting from rearrangements of Fe-Ni pairs with weak bonding nature and the second-stage relaxation due to the topological change resulting from the cooperative rearrangement of metal-metalloid pairs with strong bonding nature.View full abstractDownload PDF (927K) -
Akio Hirose, Masato Uchihara, Takao Araki, Keizoh Honda, Mitsuaki Kond ...1990 Volume 54 Issue 3 Pages 262-269
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe present study was undertaken to apply the laser welding to the joining of a shape memory alloy. Butt welding of a Ti-Ni type shape memory alloy was performed using 10 kW CO2 laser.
The laser welded specimens showed successfully the shape memory effect and super elasticity. These properties were approximately identical with those of the base metal. The change in super elasticity of the welded specimen during tension cycling was investigated. Significant changes in stress-strain curves and residual strain were not observed in the laser welded specimen after the 50-time cyclic test.
The weld metal exhibited the celler dendrite. It was revealed by electron diffraction analysis that the phase of the weld metal was the TiNi phase of B2 structure which is the same as the parent phase of base metal and oxide inclusions crystallized at the dendrite boundary. However, oxygen contamination in the weld metal by laser welding did not occur because there was almost no difference in oxygen content between the base metal and the weld metal. The transformation temperatures of the weld metal were almost the same as those of the base metal.
From these results, laser welding is applicable to the joining of the Ti-Ni type shape memory alloy. As the application of laser welding to new shape memory devices, the multiplex shape memory device of welded Ti-50.5 at%Ni and Ti-51.0 at%Ni was produced. The device showed two-stage shape memory effects due to the difference in transformation temperature between the two shape memory alloys.View full abstractDownload PDF (1715K) -
Masanobu Ohmori, Yasunori Harada, Misao Itoh, Fusahito Yoshida1990 Volume 54 Issue 3 Pages 270-275
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTensile test for sintered and cast chromiums was carried out in vacuum at temperatures up to 1273 K to exartme the dynamic strain aging behavior. Three strain rates 2.4×10−2, 2.4×10−1 and 2.4 s−1 were applied.
With increasing temperature, tensile strength decreased gradually at first and showed a minimum at a certain temperature. Above this temperature, the strength continued to increase to a maximum value. Serrated flow appeared between the temperatures of the minimum and maximum tensile strengths. A minimum tensile ductility evaluated by the fracture elongation was observed around the temperature at which the tensile strength became a maximum.
Relation between the strain rate \dotε and the temperature T of the maximum tensile strength could be well described by Arrhenius’ equation, \dotε=\dotε0exp(−Q⁄RT), where \dotε0 is a constant, Q is the activation energy for dynamic strain aging, and R is a gas constant. Activation energy of 101.3 kJ/mol was obtained, which was in good agreement with the activation energy for diffusion of the nitrogen atom in chromium.
It was found previously that chromium lost its rolling workability at temperatures above 1173 K owing to the large tensile stress in the rolling direction of the workpiece-surface in contact with rolls. The decreased rolling workability of chromium was related to the dynamic strain aging which brought about less ductility.View full abstractDownload PDF (1009K) -
Wen Huai Tian, Takeshi Sano, Minoru Nemoto1990 Volume 54 Issue 3 Pages 276-284
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFlow stress measurements were made on γ′-L12 ordered Ni3(Al, Ti) single crystals containing fine dispersion of disordered γ particles over the temperature range of 77 to 1273 K. Slip systems were determined by two-surface trace analysis. Deformation induced dislocations were also observed by transmission electron microscopy (TEM). Tilt experiments by the weak-beam method were made to obtain some information concerning the cross slip mechanism of the superlattice dislocation. The following conclusions were obtained by comparing the mechanical behavior of γ′-Ni3(Al, Ti) containing γ precipitates with that of γ′-Ni3(Al, Ti) single phase.
(1) The strength of γ′-Ni3(Al, Ti) increases over the temperature range of experiment by the precipitation of fine γ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature.
(2) Over the whole temperature range, the interaction between dislocation and γ precipitates is attractive. On the temperature range of 773 to 973 K, the dislocations in γ′ matrix move on (111) primary slip plane. When the applied stress is removed, the dislocations make cross slip into (010) plane, while those in γ precipitates remain on the (111) primary slip plane.
(3) The increase of high temperature strength in γ′-Ni3(Al, Ti) containing γ precipitates is due to the restraint of cross slip of dislocations from (111) to (010) by the dispersion of disordered γ particles.View full abstractDownload PDF (4216K) -
Wen Huai Tian, Takeshi Sano, Minoru Nemoto1990 Volume 54 Issue 3 Pages 285-291
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn investigation of the mechanical behavior of γ′-L12 ordered Ni3(Al, Ti) single crystals containing fine dispersion of disordered γ particles was perfornned for several different crystal orientations over the temperature range of 77 to 1273 K. Slip systems were determined by two-surface trace analysis and dislocation structures were observed by the weak-beam method of transmission electron microscopy (TEM). The critical resolved shear stress (CRSS) for (111)[\bar101] slip increases with increasing temperature in the temperature range where (111) slip operates, but it decreases as (010) cube cross slip commences. The CRSS for (111)[\bar101] slip is dependent on crystal orientation in the corresponding temperature range. For the samples of [001] orientation, (111)[\bar101] slip operates over the whole temperature range of experiment, but for those of other orientations, the cross slip occurs from (111) to (010). The temperature where the strength reaches a maximum (peak temperature) is dependent on crystal orientation; the higher the ratio of the Schmid factors of (010)[\bar101] to that of (111)[\bar101] (N value), the higher the peak temperature. When compared with that of the γ′-Ni3(Al, Ti) single phase the orientation dependence of CRSS and peak temperature becomes small, and it was also shown that the larger the N value, the higher the strength at the same temperature. The peak temperatures were increased by the precipitation of γ particles for the samples of all orientations. Electron microscopy of deformation induced dislocation arrangements under peak temperature has revealed that most of dislocations are straight screw dislocations. The mobility of screw dislocations decreases with increasing temperature. Above the peak temperature, dislocations begin to cross slip from the (111)[\bar101] slip system to the (010)[\bar101] slip system, thus decreasing the strength. However, for the samples of [001] orientation, cross slip does not occur up to 1073 K.View full abstractDownload PDF (1554K) -
Tadashi Yamada, Yosiyuki Fukuda, Daihachirou Sakurai, Nobuo Takeda, Te ...1990 Volume 54 Issue 3 Pages 292-300
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe necessity of evaluating dynamic fracture toughness KId of materials has been well recognized since materials are often subjected to impact loadings, but testing methods have not been well established. In this paper, a simple and reliable experimental method was proposed to evaluate KId quantitatively using precracked 3-point bending specimens. First, Kalthoff’s impact response curve (I.R.C.) for the Charpy impact testing was used to evaluate the time-dependent dynamic stress intensity factor KI(t). The validity of I.R.C. was demonstrated through a two-dimensional finite element simulation. Secondly, the initiation time (tf) of crack propagation was detected using both strain gages and crack gages in the loading rate up to \dotK∼3.1×105 MPa·m1⁄2/s, and then the KId value was evaluated using KId=KI(tf). For nodular graphite cast iron FCD37, KId was 50 MPa·m1⁄2 in the temperature range of 232 K to 323 K. The temperature dependence of KId corresponded well with that of the brittle/ductile fracture area ratio in near crack-tip regions. The estimated KId value was well above the maximum dynamic stress intensity factor anticipated in practical applications as container materials, and the reliability of FCD37 in such applications was well established.View full abstractDownload PDF (1935K) -
Shouichi Ochiai, Ikuo Yamada, Yo Kojima1990 Volume 54 Issue 3 Pages 301-306
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of heat treatment on the microstructures and mechanical properties of (NiAl+Ni3Al) two-phase alloys was investigated. A martensitic transformation was observed when the Ni-Al alloys were quenched from 1573 K. The martensite resulted in a fine two-phase structure consisting of NiAl and Ni3Al by tempering at 1073 K. Very fine lamellar structures having an equal volume fraction of the two aluminides were obtained at 34.0 mol%Al. The two-phase alloy showed high compressive strength at low temperatures. On the other hand, the flow stress of the alloy was lower than that of each constituent phase and showed an almost constant value during the plastic deformation at high temperatures such as 1073 K. The strain rate sensitivity exponent of the alloy was found to be about 0.4, which suggests that the superplastic flow occurred in the high temperature deformation of this fine two-phase alloy.View full abstractDownload PDF (1778K) -
Toshio Shimoo, Yasushi Sakai1990 Volume 54 Issue 3 Pages 307-314
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mechanism of the smelting reduction of FeCr2O4 and MgCr2O4 by graphite has been investigated. The reduction rate has been measured by means of thermogravimetry under an argon atmosphere at 1873 K using 50%CaO-50%SiO2 binary slag and 30%CaO-30%SiO2-20%Al2O3-20%MgO quaternary slag, and the dissolution of the oxide particles has been examined by microscopic observation and chemical analysis.
In the smelting reduction of FeCr2O4, the reduction of FeO component precedes that of Cr2O3. Fe-Cr-C alloy adheres poorly to the graphite and is spheroidized. In the experiment with the binary slag, the division of FeCr2O4 particles by slag attack increases markedly the reduction rate. The low solubility of chromite in the quaternary slag leads to the moderate attack and to the slower reduction. Fe-Cr-C alloy is finely distributed in the unreacted particles, too.
MgCr2O4 particles are attacked severely by the quaternary slag and are divided the much smaller ones in the early stage of the reaction. The slag wets immersionally the graphite on which the carbide layer is formed. These situations are favorable for the reduction. The retard of the reduction of MgCr2O4 in the binary slag is contributed to a lack of the wetting of the slag to the graphite and the resistance of MgCr2O4 to slag attack.View full abstractDownload PDF (1857K) -
Tadakazu Ohnishi, Akihiko Okamura, Tsuyoshi Nakayama1990 Volume 54 Issue 3 Pages 315-320
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDesign of an apparatus and operating conditions for production of pure aluminum wires by the inrotating-water spinning method, in which the molten metal jet was ejected into the water layer formed on the inner surface of the rotating drum, were investigated. Good products were obtained in the case with a lower jet velocity and with the velocity close to the water layer speed. The drum was required to rotate horizontally, because some deviation of the water layer speed from the rotating speed of drum was observed in vertical rotating and this was considered to inhibit the formation of continuous wire with a good quality. The flight length of stable jet could be predicted by the Butler’s equation employing a modified constant. Smaller incident angle of jet to the water layer was observed to be favorable.View full abstractDownload PDF (1215K) -
Genjiro Motoyasu, Atsumi Ohno1990 Volume 54 Issue 3 Pages 321-327
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSn-5 to 50 mass%Pb alloy billets were cast by the heated mold continuous casting (Ohno Continuous Casting) method developed by the authors. The surface quality, macrostructure, microstructure, tensile strength and cold rolling properties of the OCC billets were examined and compared with those of conventionally cast billets.
The OCC billets had a smooth and mirror-like surface having high level surface brightness. It is constituted macroscopically of a unidirectionally solidified structure without equiaxed crystals and microscopically of aligned primary and eutectic phases. Wrought products rolled from conventional billets tend to exhibit edge cracking and surface irregularities as rolling progresses, however the products from the OCC billets were free from such defects. In addition, the OCC Sn-Pb alloy billets enable the high-quality productions of fine wires and thin sheets solders for ICs and LSIs.View full abstractDownload PDF (2065K) -
Toshio Narita, Toshiki Mitsueda, Tatsuo Ishikawa1990 Volume 54 Issue 3 Pages 328-335
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA fully stabilized zirconia ceramics (FSZ) were joined to FSZ ceramics, chromium and nickel metals, and Kovar-alloy at 1123 K in vacuum using a Ag-Cu-Ti solder and with or without interlayers, which composed of Ni, Ni/W, and Ni/Kovar-alloy plates.
Fracture strengthes are 30 MPa for a FSZ/FSZ joint, 20-60 MPa for a FSZ/Cr joint, 82 MPa for a FSZ/(Ni/W)/Ni joint, 97 MPa for a FSZ/(Ni/W)/Cr joint, 111 MPa for a FSZ/(Ni/Kovar-alloy)/Cr joint, and 115 MPa for a FSZ/(Ni)/Kovar-alloy joint. Compositional analysis revealed that titanium in the FSZ/FSZ and FSZ/Cr joints concentrated at the ceramic/metal interface, while in joints with interlayers almost titanium existed within a solder layer.
It was suggested for the FSZ/FSZ joint that titanium in the solder degraded significantly mechanical properties of the FSZ ceramics, dark-browned in color, resulting in low fracture strengthes of the joint. When FSZ ceramics were joined using interlayers, nickel dissolved into the solder reacted immediately with titanium and copper to form initially Ni-Ti and then Ni-Ti-Cu solid phases, reducing excess reaction between titanium and ceramics. This could be ascribed to strengthen the joints with nickel interlayers.View full abstractDownload PDF (2418K) -
Shigeru Yonetani, Katsuya Imai1990 Volume 54 Issue 3 Pages 336-345
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSResidual stresses in 0.25% carbon steel and 0.45% carbon steel bar specimens which were cold drawn to cross-sectional reductions from 5 to 29% were measured. The cold drawing was carried out several times by the cross-sectional reduction of about 5% per pass. The residual stresses in the section of specimens after drawing were tensile at the outer part of the specimens, and compressive at the inner part of the specimens. The maximum residual stress at the outer part increased successively with the cross-sectional reduction to about 20%, and decreased over 20%. There are differences in the variation of the normal residual stress distribution with increasing cross-sectional reduction below and over at 20%. The textures in the outer and inner parts of these specimens were measured. The influence of the structure for the occurrence of residual stresses was discussed.View full abstractDownload PDF (1932K) -
Ryuuji Watanabe, Hisashi Andoh, Kiyoji Iwashita, Yukio Kurosawa1990 Volume 54 Issue 3 Pages 346-351
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSVarious electrodes of Ni3Al-Cr alloys were prepared for high withstand-voltage vacuum circuit breakers. The microstructures and the basic electrical properties for the electrodes were examined.
The ingots of these alloys were made by a high frequency induction melting method. In these microstructures, Cr particles were dispersed homogeneously in Ni3Al matrix.
It was found that the Ni3Al-Cr electrodes have a higher withstand-voltage than that of conventional Cu alloys, and a good interruption-ability.
The Ni3Al-Cr alloys are promising as a practical electrode material for high withstand-voltage vacuum circuit breakers.View full abstractDownload PDF (1884K) -
Yasunari Kaneko, Kei Ameyama1990 Volume 54 Issue 3 Pages 352-353
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (446K) -
Yo Kojima, Makoto Inoue, Osamu Tanno1990 Volume 54 Issue 3 Pages 354-355
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (566K)
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