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Volume 40, Issue 1
Displaying 1-16 of 16 articles from this issue
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Shigehiko Arai, Mitsuru Nagakura1976 Volume 40 Issue 1 Pages 1-6
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new processing for MnBi permanent magnets was studied. Mn-Bi specimens were obtained by the following processes:
(1) cast into metal mould→magnetic annealing (1 hr at 300°C, 5 kOe)→swaging→magnetic annealing (1 hr at 300°C, 5 kOe), and
(2) cast into metal mould→swaging→magnetic annealing (1 hr at 300°C, 5 kOe).
It was found that the specimens obtained by the process (2) showed desirable magnetic properties for parmanent magnets. In this process, swaging reduced the MnBi compounds to fine particles and caused an increase in coercive force. The following heat treatment in a magnetic field improved the value of 4πI10K and 4πIr without any decrease in coercive force. The value of maximum magnetic energy product was 6.1 MGOe in a 40 at%Mn-Bi alloy swaged to 92% reduction.View full abstractDownload PDF (837K) -
Shizuo Mukai, Makoto Fujiwara1976 Volume 40 Issue 1 Pages 6-12
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to make clear the relationship between flow stress and hardness in Fe, Fe-2%Ni and Fe-3%Ni alloys with grain sizes of 13∼69μ were studied using the tensile and Vickers hardness tests in a low temperature range. The results obtained are as follows:
(1) In linear HVf vs ε1⁄2 diagrams, the difference between HV and H0ε, obtained by extrapolating ε to zero, is large and HV equals HVf at 1∼2% strain in Fe, but the difference is smaller in Fe-2%Ni and Fe-3%Ni than in Fe.
(2) Kf and KH, Hall-Petch parameters in flow stress and hardness are large in Fe and decrease with increase in Ni content. But those are independent of temperature.
(3) σ0f and H0V are small in Fe and increase with increase in Ni content and decrease in temperature.
(4) The following approximate equation is held with regard to the specimens used:
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Parameter C decreases with increase in strain, but it is almost independent of Ni content, grain size and temperature.
(5) The above-mentioned equality are not valid for the relation between HVf and σf.
Instead, the following inequality holds:
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Fusao Togashi, Taiji Nishizawa1976 Volume 40 Issue 1 Pages 12-21
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDiffusion experiments were made on two-phase couples of ferrite (α) and austenite (γ) in Fe-C and Fe-C-M systems at 800°C. The interfacial carbon concentration in the γ phase was confirmed to deviate from equilibrium to a higher value during γ phase growth, and to a lower value during α phase growth. From the data on deviation of the interfacial composition, the mobility of the α⁄γ interface was evaluated. The results showed that the mobility of the α⁄γ interface was decreased remarkably by alloying addition of niobium, molybdenum or chromium. Such an effect of the alloying elements is quite analogous to that on the mobility of grain boundary in pure iron. This experimental fact implies that the effect of alloying elements on the mobility of the α⁄γ interface can be explained in terms of the solute drag or of other solute interactions on grain boundary migration.View full abstractDownload PDF (951K) -
Kazuaki Fukamichi, Hideo Saito1976 Volume 40 Issue 1 Pages 22-26
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPractical Invar alloys are all ferromagnetic, and applications of these alloys are often restricted because of their ferromagnetism. Therefore, research to develop magnetically insensitive Invar alloys has recently received considerable attention. In the present study, physical properties of Cr-base alloys containing small amounts of 5d transition metals have been investigated.
The Néel temperature of Cr increases with Re, Os, Ir, or Pt content and decreases with Ta or W content.
Some Cr-Fe primary solid solution alloys show very low thermal expansion coefficients below the Néel temperature, and the temperature range below room temperature, however, makes the alloys impractical. Therefore, we added 5d transition metals to the Cr-Fe alloys to increase the Néel temperature and found the Invar characteristic around room temperature in some of the Cr-Fe base ternary alloys. These Invar alloys are all antiferromagnetic and the magnetic susceptibilities are very small, showing that the Cr-Fe base ternary Invar alloys containing 5d transition metals are magnetically insensitive in practical applications.View full abstractDownload PDF (402K) -
Kazuyoshi Nii, Kazuhiro Yoshihara1976 Volume 40 Issue 1 Pages 26-32
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface self-diffusivity of α-Fe was measured by the grain boundary grooving method in hydrogen atomospheres with dew points of −60 and +13°C. The groove width measurement was made through all runs with the same region of grain boundary of a coarse-grained specimen. The diffusion anneal was carried out at 800, 850 and 890°C.
In dry hydrogen (dew point −60°C) purified through a palladium foil, the surface self-diffusivity of α-Fe can be expressed by the following equation:
(This article is not displayable. Please see full text pdf.)
The value of activation energy agrees well with that obtained by Blakely et al.
In moist hydrogen (d.p.+13°C), however, the rate of groove development was varied, depending on whether or not the specimen had been equilibrated with the atmosphere. When the specimen, which had been in equilibrium with dry hydrogen, was annealed in moist hydrogen, the development rate of groove was larger than that in dry hydrogen in the early stage, but it decreased with annealing time. On the other hand, if the specimen had been equilibrated with the same atmosphere, the grooving rate was smaller than that in dry hydrogen. In the former case, surface roughening would occur more than in thermal equilibrium owing to the adsorption and solution reactions of oxygen at the surface, which would lead to an enhancement of surface diffusivity. On the contrary, on the surface of the specimen, which is equilibrated with moist hydrogen, the blocking of kink and adatom would occur by adsorption of oxygen, which would lower the surface diffusivity.
A marked decrease in surface diffusivity in hydrogen with a dew point of +13°C was observed at 800°C with the specimen equilibrated with the same atmosphere, which could be attributed to an incidental adsorption of impurities during the sample preparation.View full abstractDownload PDF (893K) -
Atsushi Takei, Kazuyoshi Nii1976 Volume 40 Issue 1 Pages 32-38
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of Si content on the oxidation behavior of 80Ni-20Cr alloys has been studied in the repeated oxidation in air stream at the temperature of 1100°C. The addition of 1% or 5%Si to the alloys lowered the weight gain in oxidation, whereas the amount of spalling of oxide scale was increased with the addition of Si. The structures of oxide layers observed by microphotography, X-ray diffraction and electron probe microanalysis (EPMA) were different with the Si content of alloys. The oxide layer of the alloy with 1%Si consists of multilayers, that is Ni oxide, Cr2O3 and SiO2 as the external oxide layer. The oxide layer remained on the alloy with 5%Si, however, consists of a single oxid layer of Cr2O3 containing small amounts of Si and Ni. Inspite of the fact that the amount of Si in this alloy is larger than that of the alloy with 1%Si, the SiO2 oxide layer was not observed at the interface of alloy-oxide. It was found by EPMA that the concentration of Si in the oxidized 5%Si alloy substrate was increased in the vicinity of the surface, although Si in the 1%Si alloy was depleted.
From the above results the internal oxidation of Si is assumed in the near surface region of 5%Si alloy. The internal oxidation of 5%Si alloy was confirmed by an increase in hardness in the near surface region.
The difference in oxidation behavior between the 1%Si and 5%Si alloys can be understood under the assumption that the oxide layer formed on 5%Si alloy contained much larger amounts of Ni and Si than that on 1%Si alloy, and that this oxide layer tends to crack more easily, thus being less protective for the penetration of oxygen.View full abstractDownload PDF (800K) -
Akio Tanihuji, Zyuzo Kurihara, Hiroshi Kaga1976 Volume 40 Issue 1 Pages 39-44
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDynamic characteristics, especially instability of an impact force measuring system subjected to impact tension loading have been studied theoretically and experimentally. The results are summarized as follows:
(1) The measuring system behaves unstable owing to the energy balance between kinetic energy of a tip and the absorption energy of the system.
(2) Instability of the system can be described by three kinds of two-degrees of freedom-mass-spring models and the transition among these models.
(3) The effects of experimental conditions such as impact velocity and dimension of a specimen on instability of the system are clarified.View full abstractDownload PDF (818K) -
Shotaro Morozumi, Michio Kikuchi1976 Volume 40 Issue 1 Pages 45-50
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of alloying elements, Cr, Fe, Mo, Nb, Ti, V and Zr, on solution and age-hardening of Ni-Be alloys was investigated by testing hardness and tensile properties at room and high temperatures, as well as by microscopic examination of the grain-boundary reaction.
The results obtained are as follows:
(1) Solution-hardening effect of the alloying elements was correlated to a factor consisting of the atomic size and amount of the alloying elements.
(2) In Ni-low Be alloys containing less than about 1 wt% of Be, age-hardenability of the alloys was improved by the alloying.
(3) While, in Ni-high Be alloys with various amounts of the alloying elements, the maximum increment of hardness attainable by aging was not so different from alloy to alloy. However, the attainable maximum hardness by aging was improved by the alloying because of the increased hardness of solution-treated alloys.
(4) Microscopic examination showed that among the alloying elements, Ti and Nb retarded the grain-boundary reaction excellently and Mo did fairly.View full abstractDownload PDF (747K) -
Tadashi Nishihara, Nobuhiro Iguchi1976 Volume 40 Issue 1 Pages 51-56
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this paper the abnormal behavior of shape recovery appeared on the transformation superplastic deformation of Ti-6Al-4V was examined, with particular emphasis on the recovery during (α+β)→β transformation.
The main results obtained were as follows:
(1) The material after the superplastic deformation exhibited an irreversible shape-memory effect during (α+β)→β transformation under stress free heating.
(2) The shape recovery depended on the factors affecting the transformation superplastic deformation such as the maximum temperature of thermal cycle, heating rate and applied stress. The perfect shape recovery trended to be appeared under the intensive superplastic deformation defined by the strain rate sensitivity exponent, m=1.
(3) The relation between the transformation superplasticity and the shape memory effect could be expressed using 4-parameters-Rheology-Model.View full abstractDownload PDF (532K) -
Kazuo Hosokawa1976 Volume 40 Issue 1 Pages 57-61
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA boro-carburizing method using a hot bath consisting of B4C, BaO and alkali halides (KCl, NaCl) has been studied. The results obtained are summarized as follows.
(1) The following reactions seem to take place in the bath.
(This article is not displayable. Please see full text pdf.)
The impregnation of iron and steel with boron and carbon seems to be accelerated by MO.
(2) In a hot bath consisting of B4C and alkali halides, the simultaneous impregnation of iron and steel with boron and carbon was not remarkable. However, the impregnation increased significantly by the addition of BaO to the bath. The thickest, about 0.28 mm, boronized layer was obtained by treating in a hot bath of 24%B4C, 16%BaO, 30%KCl, and 30%NaCl at 1000°C for 5 hr. The layer consists of FeB and Fe2B.View full abstractDownload PDF (495K) -
Itsuo Ishigami, Mamoru Nakamura, Kyuhiko Yamanaka1976 Volume 40 Issue 1 Pages 61-69
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWhen a polished section of high speed steel tempered after being vacuum oil-quenched is etched, a white layer about 15 to 40μ thick is observed at the edge of the section. Some properties of the white layer produced on the specimen SKH-9 are clarified by means of an optical microscope a micro-vickers hardness tester, an electron probe microanalyzer, and an X-ray diffractometer.
The main results obtained are as follows:
(1) The white layer is formed only on the specimen tempered after being vacuum oil-quenched.
(2) Carburization is the direct cause for the formation of the white layer.
(3) This layer consists of a small amount of M6C-type carbide as well as coarse martensite and of a large amount of retained austenite. Consequently, the white layer has low hardness.
(4) The thickness of the layer increases as quenching temperature is raised, and is also affected by the size and form of the specimen. It is however independent of holding time at the austenitizing temperature.
(5) The resistance of the white layer to decomposition on tempering increases as the Cr content is increased.
(6) The maximum hardness zone composed of M6C-type carbide and coarse martensite of high carbon content exists in the inside of the boundary between the white layer and the matrix.View full abstractDownload PDF (1407K) -
Itsuo Ishigami, Kyuhiko Yamanaka1976 Volume 40 Issue 1 Pages 69-76
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to analyze the mechanism of the carburization that is the direct cause for the formation of the white layer produced on the high speed steel tempered after being vacuum oil-quenched, the relations between heat-treatment conditions and case depths were investigated and the decomposed gas produced from the quenching oil was analyzed using pure iron and S15C as quenching specimens. It was clarified that the specimen was carburized in the oil on quenching, and that the occurence of the carburizing on vacuum oil-quenching required the following conditions:
(1) Specimens are heated in vacuum to clean prior to quenching.
(2) Quenching temperature is sufficiently high to form a vapor film in quenchant after specimens are quenched in it.
(3) Quenchants decompose to produce the carburizing gas as a result of heating.
(4) The carbon content in austenite is under the solubility limit on quenching.
The present results give reasonable explanations for the facts that the white layer is formed only on the vacuum oil-quenched high speed steel and that the thickness of the white layer increases as the quenching temperature is raised and is affected by the size and form of specimens although it is independent of holding time at the austenitizing temperature. When the formation of the white layer is not desirable, oil-quenching of the specimens after gas-cooling to a certain temperature is one of the methods for suppressing its formation.View full abstractDownload PDF (956K) -
Takayoshi Ozawa, Yoichi Ishida1976 Volume 40 Issue 1 Pages 77-84
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMössbauer spectrum of tin atoms segregated at the grain boundary of Zn-Al eutectoid was analyzed in regard to the binding state of impurity elements located at the grain boundary. The segregation of impurity atoms is generally considered as the major cause of the grain boundary brittleness. It is interesting to know whether the phenomenon can be explained by the binding state of the segregated impurity atoms.
The present alloy is of two phases, but the grain size is small. The solid solubility of the tin atoms in both phases is very low and no intermetallic compound should occur. Consequently, the ratio of tin atoms segregated at the boundary is large even in an equilibrium state.
Experimental conditions to analyze the electronic and vibrational state and the diffusion constant of the segregated tin were examined at first. A Mössbauer source nucleus 119mSn was doped at 100∼250°C, while the measurement of the spectrum were carried out at −190∼−113°C.
Changes in the spectrum with the doping temperature were explained by the diffusion of tin atoms through the boundary, α and β grains.
It was concluded that the spectrum doped at 100°C was due mainly to tin atoms segregated at the grain boundary. The peak position of the spectrum showed that the average density of S electrons at the tin nucleus site is much higher than that of tin in solid solutions and almost equal to that of isolated tin, while the change in the peak area with the specimen temperature indicated that the Debye temperature and average force constant of the segregated tin are much lower than that of tin in solid solution.View full abstractDownload PDF (782K) -
Minoru Nobuki, Atsushi Oguchi1976 Volume 40 Issue 1 Pages 85-88
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA heat treated alloy steel (0.39%C, 0.77%Mn, 1.81%Ni, 0.78%Cr, 0.23%Mo) was tested in tension at atmospheric pressure under 12000 kg/cm2 at room temperature in order to investigate the behavior of the increase in ductility under hydrostatic pressure and the possibility of the increase in tensile strength of the material prestrained under pressure. The results obtained are as follows: (1) The density of cracks generated due to plastic deformation is observed to be the same order of magnitude both by the prestrainings at atmospheric pressure and under 12000 kg/cm2 at small strains. However, with increasing amount of prestraining, the crack density becomes larger at atmospheric pressure. Moreover, when the material is deformed under high hydrostatic pressure, it can be deformed further even to the strains where the crack density is larger than that observed just before fracture at atmospheric pressure. (2) When the quenched material is tempered at various temperatures and prestrained under 12000 kg/cm2, or vice versa, the tensile strength is observed to be higher with lower tempering temperature and larger prestrain. In these cases, it can be thought that the former is more advantageous than the latter because of larger residual strain to fracture.View full abstractDownload PDF (497K) -
Hideo Sugawara, Tetuo Hanami1976 Volume 40 Issue 1 Pages 89-96
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe susceptibility of high purity Fe-Cr alloys containing 18%Cr, 0.003 to 0.05%C and 0 to 5%Ni was determined by an electrochemical method after subjecting the alloys to various heat treatments. Some data on the occurrence of the second anodic current maximum (SACM) observed on the anodic polarization curves of the alloys are presented and applied to the interpretation of the mechanism of intergranular corrosion in ferritic stainless steels. SACM is sensitive to heat treatment (degree of senstization). Air cooling from 1050°C causes an increase in SACM which is very high in 18%Cr steel with more than 0.004%C. The sensitization which develops in such alloys upon air cooling from 1050°C develops at temperatures below 800°C. Addition of 1∼2%Ni causes a remarkable decrease in SACM of 18%Cr steels air cooled from 1050°C, but there is a rather sharp change in SACM for these alloys furnace cooled from 1050°C. The tendency of 18%Cr steel to become sensitized to intergranular corrosion is closely related to the amount of C in α and γ phases and the area fraction of each phase. This investigation lends support to Cr depletion theory for sensitization.View full abstractDownload PDF (1292K) -
Ichiro Kawakatsu, Seiji Kitayama1976 Volume 40 Issue 1 Pages 96-103
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMetallographical phenomena among many factors which control weldability on diffusion bonding has been investigated. Combinations of the base metals were classed into three types; the solid solution type, two-phase type, and intermetallic compound type. Diffusion bonding was carried in the hydrogen atmosphere using several bonding pairs such as Cu-Ni, Cu-Ag, Cu-Al and Fe-Al prepared from cold rolled sheets. Influence of the bonding temperature and time on bonding strength was investigated and the microstructure at the interface was observed.
The results obtained were as follows.
(1) Minimum bonding temperature exists in the neighbourthood of softening temperature of one of two base metals. Especially, in the solid solution type, the bonding strength increased at the softening temperature of one of two base metals.
(2) The increasing process of initial bonding strength is considered as a transient phenomenon from recovery to recrystallization with stored energy and depends on the bonding temperature and time, satisfying Arrhenius’ equation.
(3) Bonding strength depends on softening of base metals and alloying at the interface above the recrystallization temperatures of base metals.
(i)\phantomii In the case of the solid solution type, the bonding strength increases with the rise of the bonding temperature and time.
(ii)\phantomi In the case of Cu-Ag joints, the effect of bonding conditions is not very large, but the bonding strength increases rapidly after 30 min heating at 700°C.
(iii) In the case of the intermetallic compound type, the alloy layer increases in thickness and the bonding strength deteriorates in Fe-Al joints rapidly above the recrystallization temperature.
(4) Bonding interface tends to disappear as time elapsed above the recrystallization temperature of both base metals of the solid solution type, but it is retained as an interfacial boundary in the case of the two-phase type and intermetallic compound type.View full abstractDownload PDF (1527K)
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