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Volume 38, Issue 3
Displaying 1-14 of 14 articles from this issue
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Hisaoki Sasano, Shinichi Komori, Hirozo Kimura1974 Volume 38 Issue 3 Pages 199-205
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe phase transformations and their effects on hardness in Ti-6Al-4V during solution treatment and aging were investigated using the α and β alloys containing the same amounts of Al and V in the α and β phases which are in equilibrium in Ti-6Al-4V at temperatures from 770 to 1000°C. In Ti-6Al-4V solution treated at 750°C, a small amount of the β phase is retained and the existence of the β phase causes remarkable softening of the alloy. For the examination of the aging process of the alloy, considerations should be given not only to the phase transformations in the α and the β grains present at the solution treatment temperatures but also to those in the vicinity of the interface between α and β which arise from the movement of the interface and the migration of solutes. The latter transformations exert a remarkable influence on the hardness of the alloy.View full abstractDownload PDF (636K) -
Yoshiyuki Mizutani, Yasuo Imada, Koichi Nakajima1974 Volume 38 Issue 3 Pages 205-213
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSulfides and Selenides formed in Fe-M-S and Fe-M-Se ternary alloy systems (M: Mo, W, V, Ta) were investigated by means of optical and electron microscopy, electron probe microanalysis and X-ray diffraction.
The results obtained are as follows:
(1) TaS2 and MoSx were formed in Fe-Ta-S and Fe-Mo-S alloys, respectively. The structure of MoSx was considered to be one of the defect structures of MoS2 having x\fallingdotseq1.8.
(2) VSe, TaSe2 and molybdenum selenide (MoSex) were formed in Fe-M-Se and FeSe in Fe-W-Se alloy systems.
(3) The formation of chalcogenides of Ta and Mo in the ternary alloy systems was observed at relatively higher contents of M and their quantity increased in the case of the higher alloying elements depending on the ratio of M to S (or Se).
(4) Thin layers of MoSx and VS were formed on the surface of Fe-Mo-S and Fe-V-S alloy systems during annealing in vacuum at high temperature.View full abstractDownload PDF (1675K) -
Yoshiyuki Mizutani, Yasuo Imada, Koichi Nakajima1974 Volume 38 Issue 3 Pages 213-219
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFriction and wear properties of Fe-M-S ternary alloy systems were examined and it was found that (1) the coefficient of friction decreased with the content of M (: V, Ta, Mo or W) in every alloy system, (2) molybdenum sulfide layer formed on the surface of Fe-M-S alloy improved its frictional property, especially at the beginning of sliding and (3) wear of Fe-M-S alloy also decreased with the content of M.
Furthermore, changes in the structure of the surface layers due to friction were investigated by means of optical microscopy, X-ray diffraction and EPMA analysis. It was shown that (1) sulfide crystallites were fragmented during sliding, making a homogeneous film on the surface in a stationary state of friction and (2) molybdenum sulfide and FeO were formed on the surface of Fe-Mo-S alloy during sliding.View full abstractDownload PDF (960K) -
Kenji Matuki, Yasuhide Ueno, Masao Yamada1974 Volume 38 Issue 3 Pages 219-226
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study on the role of grain boundary sliding in the superplastic deformation of an Al-Zn-Mg alloy has been carried out in the temperature range of solid solution. The main results obtained are as follows:
(1) The contribution of grain boundary sliding to total strain is greatest when the strain rate sensitivity of flow stress is highest. It is considered, therefore, that the grain boundary sliding is the predominant mode of superplastic deformation of the alloy.
(2) The rotation of grains takes place during superplastic deformation.
(3) Dislocation arrays toward the grain boundary are observed in the specimens deformed under a superplastic condition. After deformation at a higher strain rate where m becomes small, dislocation tangles or cell structure are observed.
(4) Superplastic behavior of this alloy can be well explained in terms of grain-boundary sliding which is probably controlled by dislocation motion within the grains as well as by grain boundary migration.View full abstractDownload PDF (1295K) -
Hideaki Kimura, Tsutomu Yanagase, Fumio Noguchi, Yasuaki Ueda1974 Volume 38 Issue 3 Pages 226-232
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mechanism of CaO dissolution into slag has been investigated by observing the melt heated on Pt-filament directly through the microscope. After the CaO crystal was treated in the molten slag, distributions of Ca, Si and Al formed around the CaO were determined by XMA technique. The results indicate that the layer of 2CaO·SiO2 is formed on the CaO crystal in CaO-SiO2 melt, and between CaO and the newly formed compound the molten slag tends to migrate through the crack, resulting in accelerating the solution rate of CaO. In CaO-SiO2-Al2O3 melt the compound formed on the surface of CaO depends on the composition in the phase diagram. The addition of CaF2 into CaO-SiO2 melt accelerates the solution rate of CaO as well as that of the compound layer.View full abstractDownload PDF (988K) -
Yasuhiro Miura, Yutaka Igarashi, Hiroya Kaieda1974 Volume 38 Issue 3 Pages 233-237
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of isothermal and thermal-cyclic annealing on substructures in pure Aluminum were studied by means of transmission x-ray topography. An x-ray topograph of a thin crystal was taken after each annealing stage, and changes in substructures, mainly in subboundary or dislocation-bundles, were studied as functions of the time and type of annealing.
The results show that substructures of single crystals are more simplified as the time of annealing become longer, and relatively stable subboundaries are formed through the break-down or recombination of smaller angle boundaries and/or dislocation groups. Once relatively stable subboundaries are formed, it seems that a thermal-cyclic annealing is more effective to break and untie them than an isothermal annealing.View full abstractDownload PDF (857K) -
Hakaru Masumoto, Yuetsu Murakami, Masakatsu Hinai1974 Volume 38 Issue 3 Pages 238-241
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagnetic properties, electrical resistivity and hardness were measured with vacuum-melted Ni-Fe-Nb alloys heated in H2 over a temperature range 950 to 1350°C and then cooled at various rates from temperatures above the order-disorder transformation points. It has been found that the highest values of initial and maximum permeabilities in each alloy increase, reach a maximum at about 9%Nb and then rapidly decrease with increasing Nb content. An alloy of 79.27%Ni, 11.76%Fe and 8.97%Nb shows the highest initial permeability of 125000 when cooled at a rate of 300°C/hr after annealing at 1150°C for 2 hr. An alloy of 79.19%Ni, 12.16%Fe and 8.65%Nb exhibits the highest maximum permeability of 580000 when cooled at a rate of 400°C/hr after annealing at 1250°C for 1.5 hr. The former shows a coercive force of 2.3 m Oe, and a hysteresis loss of 2.7 erg/cm3/cycle for the maximum magnetic induction of 5 kG. The electrical resistivity of this alloy is 74.8 μΩ-cm, its Vickers hardness being 207. These alloys have been named “Hardperm”. The high permeability of Ni-Fe-Nb alloys appears to be due to the low value of magnetostriction with the purification, homogenization and grain growth by annealing, and the proper ordering state resulting from the effect of cooling.View full abstractDownload PDF (318K) -
Tsuneo Satow, Toyojiro Isano, Toshio Honma1974 Volume 38 Issue 3 Pages 242-246
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe oxidation behavior of the intermetallic compound TiNi in air was investigated in the temperature range between 750 and 950°C under atmospheric pressure. The rate of oxidation was determined by the weight increase using a direct reading semi-microbalance. Photomicrographic, electron microprobe, X-ray diffraction and marker studies of the oxidized specimens were carried out. Except for the initial stages, the rate of oxidation is parabolic and the activation energy is 59 kcal/mol. Titanium is selectively oxidized and the oxide grows at the metal-oxide interface. The oxidized specimen has a layer structure of TiO2 (rutile), the TiO2 phase containing TiNiO3 particles, a porous Ni phase containing Ti, the TiNi3 phase and the TiNi phase in sequence from the outer side. Rate determining process of the overall oxidation is the inward diffusion of oxygen ions through the oxide (rutile) layer. The rate of oxidation is slightly faster than that of pure titanium.View full abstractDownload PDF (462K) -
Asahi Kawashima, Michinori Takano, Koji Hashimoto, Saburo Shimodaira1974 Volume 38 Issue 3 Pages 247-254
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of strain rate, applied potential, pH, temperature and H2S concentration on the sulfide cracking of mild steel were studied at constant strain rates by means of an Instron-type tensile test machine. The results obtained are as follows:
(1) The susceptibility of sulfide cracking is highest in the strain rate region of 10−6∼10−5 sec−1 and decreases in the higher strain rate region.
(2) In both solutions with and without H2S, the lower the pH of solutions the higher is the susceptibility to cracking, which varies almost linearly with pH. The H2S addition to the solution is most effective for the embrittlement at pH 4.7 and above pH 5 the embrittlement index decreases rapidly. The embrittlement indices below pH 4 are almost identical but slightly decrease with the lowering of pH.
(3) The susceptibility to the sulfide cracking varies linearly with applied potential, decreasing with anodic polarization and increasing with cathodic polarization.
(4) The embrittlement index is highest at 50°C.
(5) The change in H2S concentration has little effect on the susceptibility to cracking.
(6) The cracking susceptibility is not directly related to the presence of an iron sulfide film on the steel surface.
(7) The dissolved species which promotes hydrogen embrittlement in hydrogen sulfide solutions has turned out to be an undissociated, molecular H2S.
(8) The sulfide cracking of mild steel is caused by hydrogen embrittlement.
(9) The constant strain rate method is suited for quantitative comparison of changes in susceptibility to the hydrogen embrittlement of steel.View full abstractDownload PDF (647K) -
Asahi Kawashima, Michinori Takano, Koji Hashimoto, Saburo Shimodaira1974 Volume 38 Issue 3 Pages 254-260
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSulfide cracking of mild steel at a constant strain rate of 4.4×10−5 sec−1 in H2S solutions was studied by scanning electron microscopy. Particular attention was given to effects of pH, applied potential and temperature on the morphology of the fracture surface of the steel. The following results were obtained.
(1) The mild steel specimens exhibit mainly transgranular quasi-cleavage fracture at the open circuit potential in acidic H2S solutions.
(2) The specimens also show mainly transgranular quasi-cleavage fracture when a large quantity of hydrogen is absorbed by cathodic polarization, while under anodic polarization or at high pH, a ductile dimple pattern becomes predominant on the fracture surface.
(3) Nucleation sites of cracks appear to be carbides in the pearlite, inclusions or grain boundaries.
(4) Intergranular corrosion and cracks are observed on the steel surface. However, intergranular corrosion does not lead to the rupture of the steel.
It follows from above results that the sulfide cracking of mild steel is attributed to hydrogen embrittlement.View full abstractDownload PDF (1778K) -
K\={o}ji Shimizu, Heihachi Shimada1974 Volume 38 Issue 3 Pages 261-267
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of crystal boundaries on the mechanical behavior of metal have been the subject of numerous investigations. There are many reports concerned with the comparison between the yield stress or initial work-hardening rate of a single crystal and that of a bicrystal. However, most of these investigations have been carried out from a microscopic point of view. Considering that it is important to macro-scopically study the mechanical behavior of these crystal boundaries together with the composite materials, the present authors have experimentally investigated the stress distribution in the vicinity of the adjoining boundary for simple bar models by using the photoelastic and interferometric methods.
In the present paper, with these model tests as the background the mechanical behavior of the crystal boundary has been observed from a macroscopic point of view.
The strain distribution in the non-isoaxial bicrystals of pure aluminium having the grain boundary aligned at 0°, 30°, 45°, 60° and 90° to the tension axis is systematically investigated by the whole field method, i.e., the photoelastic coating method, and the results are compared with those of the model tests. It is shown that the deformation patterns of the bicrystals with θ=0° are divided into three groups. In the case of the bicrystals with θ=30°∼90°, the strain on the grain boundary is very small and the strain distribution in the vicinity of the grain boundary can be roughly obtained by superposing the strain constraint in the grain boundary on the result of the model test.View full abstractDownload PDF (583K) -
Y\={u}ichiro Murakami, Norihiko Nakanishi1974 Volume 38 Issue 3 Pages 267-271
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPhase diagram of AgZn1−xCdx alloy is investigated. There appear β (disordered bcc), ζ (hexagonal) and β′ (CsCl-type ordered cubic) phases in the Ag-Zn-Cd alloy. The β′ phase is metastable and Tc of order-disorder (β′-β) transition is not directly observed because of the appearance of the ζ phase. When Au atoms are added to the alloy, Tc increases with increase in Au content and the ζ phase disappears. Therefore the hypothetical critical temperature Tc of the CsCl-type superstructure in AgZn1−xCdx alloy can be estimated by extrapolating the Tc of Ag1−mAumZn1−xCdx to m=0. As a result, Tc of the AgZn1−xCdx alloy increases with increase in Cd content after a minimum at Cd 10 at%. The Tc of AgZn and AgCd is determined to be 250 and 325°C, respectively. The composition dependence of Tc in the AgZn1−xCdx alloy is treated by statistical thermodynamics with the Bragg-Williams approximation.View full abstractDownload PDF (378K) -
Kusuhiro Mukai1974 Volume 38 Issue 3 Pages 271-278
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relationship between the interaction parameter ε2 in 1(3) in a ternary liquid alloy and the valency of the composite element of the alloy was derived based on the ionic solution model, composite ions of which are the ions of the composite element of the alloy and the electron or the positive hole released from the element.
On the approximation that the valency is equal to the effective number of free electrons, the above derived relationship gives a reasonable explanation of the relations between the valency and the previous experimental values ε2 in 1(3) for a number of ternary liquid alloy systems except for a few cases for εO in Fe(X), etc.
The relationship is useful for the prediction of the interaction parameters εC in Fe(X), εH in Fe(X), εMn in Fe(X), εN in Fe(X), εS in Fe(X), εN in Co(X), εH in Cu(X) and εN in Ni(X) in infinite dilute solution by use of the effective number of free electrons.
A few exceptional interaction parameters, εO in Fe(X), etc., are briefly discussed thermodynamically and from the standpoint of experimental errors.View full abstractDownload PDF (609K) -
Tadao Ishihara, Yoshihiko Shimizu, Shigeo Ohashi, Goro Ito1974 Volume 38 Issue 3 Pages 278-285
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInvestigations were carried out on the effects of small amounts of impurities such as carbon, silicon, manganese, phosphorus, nitrogen and nickel in Fe-18%Cr ferritic stainless steels on the susceptibility to stress corrosion cracking in high-temperature water.
The experimental Fe-18%Cr alloys were vacuum-melted in an induction furnace using pure iron and chromium, and in which the impurities mentioned above were added. The sheet specimens were subjected to two kinds of heat treatment, that is, annealing at 800°C and sensitizing at 1050°C.
Stress corrosion tests were conducted in a 4 liter autoclave containing a chloride solution with a concentration of 600 ppm chloride ion. The stressed U-bend specimens were exposed at 300°C for 300 hr under the undeaerated condition.
The results were summarized as follows:
(1) Te greater susceptibility of the commercial AISI type 430 steel to stress corrosion cracking compared with the immunity to cracking of experimental high-purity 18Cr alloys was attributed to the presence of impurities such as carbon and nitrogen in the steel. Other impurities such as silicon, manganese, phosphorus and nickel showed little or no effect on stress corrosion cracking.
(2) The susceptibility of 18Cr alloys containing such impurities detrimental to stress corrosion cracking as carbon or nitrogen was remarkably affected by the heat treatment; the alloys annealed at 800°C were immune to cracking, whereas those sensitized at 1050°C were susceptible. All of the cracks were intergranular in nature.
(3) Sensitized 18Cr stainless steels containing carbon and/or nitrogen were revealed to be susceptible to intergranular corrosion, when boiled in copper sulfate solution (Strauss test) or in nitric acid solution (Huey test).
(4) Results of polarization tests on 18Cr stainless steels in high temperature water showed that failures were accelerated by an application of anodic current, but prevented by cathodic current.
(5) On the basis of the data obtained, it was concluded that intergranular stress corrosion cracking of sensitized 18Cr stainless steels in high-temperature water was attributed to the preferential dissolution of grain boundaries caused by the precipitation of chromium carbide or nitride at that area. In other words, the cracking was proceeded by a stress-assisted anodic dissolution mechanism.
(6) The addition of Ti or Nb was beneficial to prevent the intergranular stress corrosion cracking of 18Cr stainless steels.View full abstractDownload PDF (866K)
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