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Volume 38, Issue 12
Displaying 1-17 of 17 articles from this issue
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Shizuo Mukai, Makoto Fujiwara, Masayuki Serino, Takayuki Kawano1974 Volume 38 Issue 12 Pages 1085-1088
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFrom the hardness test, the effects of composition and temperature on the flow stress in Fe-Ni alloys have been studied to ascertain the deformation controlling mechanism and the correspondence between micro-crack transition temperature, Tm and TV*=0, the temperature at which the activation volume, V* apparently equals zero. TV*=0 was obtained from extrapolating V* to zero in the V*⁄kA vs T1⁄2 curve. V* is considered not to be zero except 0°K, but it can be taken as zero apparently in the micro-crack transition temperature range in the tensile test. The results obtained are as follows:
(1) Considering ln(ν⁄\dotγ) to be constant, the V*⁄kA vs τ* curve can be obtained, where kA is constant.
(2) The deformation controlling mechanism in Fe, Fe-3.3%Ni and Fe-6.9%Ni is found to be identical from the V*⁄kA vs τ* curve.
(3) TV*=0 corresponds well to Tm in Fe and Fe-3.3%Ni.View full abstractDownload PDF (282K) -
Jo Yamamoto1974 Volume 38 Issue 12 Pages 1088-1096
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe mechanical properties and fracture behaviors of the martensite and austenite two-phase structures in the age-hardenable Fe-12%Ni-6%Mn alloy containing 0.15%C were studied. The results obtained in this study are summarized as follows:
(1) The mixed structures containing 20∼30 vol% of the relatively stable austenite obtained by both air-cooling from 1000°C, followed by subzero-treatment at −196°C and over-aging at 525°C for 1 hr, show a good combination of strength, ductility and toughness, such as 95∼102 kg/mm2 in 0.2% proof strength, 135∼118 kg/mm2 in tensile strength, 21∼22% in elongation, 41∼47% in reduction of area and 8.2∼2.7 kg·m in Charpy shelf energy. It is found that the strength, ductility and toughness of the Fe-12%Ni-6%Mn alloy are improved effectively by the addition of 0.15% carbon.
(2) Without regard to the differences in the amount and stability of austenite, the brittle fracture caused by the hardened martensite is found in the mixed structures aged at 450°C for 1 hr.
(3) In the mixed structures containing 55∼80 vol% of the unstable austenite, remarkable TRIP phenomena are observed. These structures are obtained in both the non-aged state and the over-aged state at 525°C, and show low proof strength, high tensile strength, good ductility and fairly high toughness. Some of the non-aged specimens, however, show lower ductility in tensile tests. It seems that this low ductile fracture may occur due to the banded martensites distributed narrowly in the unstable austenite matrix. Therefore, in these cases, the over-aged state is more preferable than the non-aged state when the alloys are used under TRIP behavior.View full abstractDownload PDF (1372K) -
Hitoshi Hamanaka, Kazuko Takahashi, Ishi Miura1974 Volume 38 Issue 12 Pages 1096-1102
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDirectional control of eutectoid growth in Cu-11.8 wt%Al alloy was studied under temperature gradients in the range of 300∼750°C/cm, and an attempt to produce lamellar composite has been made. The temperature gradient is an important factor to align the pearlitic structure, especially at higher transfer rate. Pearlitic transformation occurred at transfer rates up to 5 mm/hr, but an aligned composite structure was obtained at transfer rate below 4 mm/hr under the temperature gradients used in this study. The following relationship between the interlameller spacing λ and growth rate v has been obtained experimentally: v·λ2.3=const.. This relationship is independent of temperature gradient.
From observation of structures of quenched interface, the pearlitic transformation is thought to advance by successive growth of pearlite colonies. For directional transformation, pearlite colonies are parallel to the heat flow direction under higher temperature gradient and/or lower transfer rate, and a well-aligned structure is obtained. On the contrary, under lower temperature gradient and/or higher transfer rate, pearlite colonies are not always parallel to the heat flow direction, and less directional structures are obtained.View full abstractDownload PDF (1576K) -
Namio Ohtani, Yasunori Hayashi1974 Volume 38 Issue 12 Pages 1103-1110
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe crack propagation period, tc, of stress corrosion cracking (SCC) is formulated as a function of tensile strength, applied stress, plastic deformability, the apparent activation energy of the anodic dissolution process and others by using a simple mechanochemical model. Some characteristics of SCC are interpreted by this formula. The following points are clarified in the present work:
(1) The relation among time to fracture, tf, applied stress, σa, and pre-working is well explained.
(2) It may be possible to distinguish the electrochemical one-step mechanism from the mechanical and electrochemical two-step mechanism based on the shape of tf-σa curve.
(3) There is a relationship, 4⁄3Qc=ΔH+ΔH1, between apparent activation energies for the crack propagation process, Qc, the anodic dissolution process of newly formed slip planes, ΔH, and the deformation process, ΔH1.
(4) ΔH for the anodic dissolution process of 18-8 stainless steel in MgCl2 solutions is evaluated to be about 6 kcal/mol.View full abstractDownload PDF (617K) -
Kenzo Kon, Namio Ohtani1974 Volume 38 Issue 12 Pages 1110-1114
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe characteristics of stress corrosion cracking of Al-4%Cu single crystals, prepared by the Bridgman method, was examined by a mechanochemical mechanism proposed previously. The induction and crack propagation periods, ti and tc, were determined from elongation-time curves. Induction period ti is almost constant and independent of applied stress σa up to the yield point σy, but rapidly decreases when σa exceeds σy and becomes to zero when σa exceeds 8 kg/mm2. The crack propagation period tc decreases smoothly with increase in σa. The stress dependence of the crack propagation period is well explained by a mechanochemical model in which the dissolution process at the crack tip is rate-determining. The activation energy Qc of the crack propagation process is estimated to be 10 kcal/mol. On the other hand, the activation energy ΔH1 of the deformation process, obtained from the temperature dependence of the steady state creep rate, is evaluated to be 8.9 kcal/mol. According to the mechanochemical dissolution model, the activation energy ΔH of the dissolution process of newly exposed slip planes is calculated to be 4.4 kcal/mol.View full abstractDownload PDF (698K) -
Toshio Shimoo, Hiroshi Kimura, Masao Kawai1974 Volume 38 Issue 12 Pages 1115-1122
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this study the absorption of N3−, CN− and C22− in CaO-Al2O3 binary slag melted in a graphite crucible was investigated. The following results were obtained.
(1) As the mixed potential is more basic with increasing lime content, the absorption of nitrogen and carbon is accelerated. It is supposed that the reaction current of N3− approaches the limited current in the case of the sufficiently basic mixed potential.
(2) The behavior of the absorption of N3−, CN− and C22− shows a remarkable difference between an atmosphere of N2-Ar and a N2-CO gas mixture. This may be due to the different effect of these atmospheres on the polarization character.
(3) In the slag contained in an excess of carbon, the behavior of N3−, CN− and C22− is complicated and is divided into two stages.
(4) It is predicted that the absorption of carbon in slag is cathodic controlled.View full abstractDownload PDF (591K) -
Kazuo Hosokawa, Masuzo Ueda, Fumio Seki1974 Volume 38 Issue 12 Pages 1122-1128
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new hot bath carburizing without cyanide was examined. It is based on the mechanism of carburizing during boro-carburizing of iron impregnated simultaneously with boron and carbon. The hot bath consists of neutral salt (KCl and NaCl), any one of carbonates (K2CO3, Na2CO3, Li2CO3, SrCO3, BaCO3), and any one of Si, SiC, charcoal and graphite. The results obtained are summarized as follows:
(1) Carburizing of iron seems to be caused by the gas produced according to the following reactions:
(This article is not displayable. Please see full text pdf.)
(2) The suitable compositions of the carburizing bath are (1) 10%Si, 40%Na2CO3, 25%KCl, and 25%NaCl, (2) 15%SiC, 35%K2CO3 or Na2CO3, 25%KCl, and 25%NaCl, and (3) 15% charcoal, 35%K2CO3, 25%KCl and 25%NaCl.
The thickness of the carburized layer obtained is: (1)—about 2.0 mm, (2)—about 1.6 mm, and (3)—about 1.7 mm at 1000°C for 4 hr.View full abstractDownload PDF (612K) -
Kiichi Arakawa, Tadashi Sawatani, Hisao Ochi1974 Volume 38 Issue 12 Pages 1129-1137
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSVarious inorganic methods have been attempted to obtain pure iron which will be used for a basic study of properties of iron and steel. More recently the zone melting method has been applied to the purification of iron. However, it is almost impossible even by this method to remove some metallic impurities in iron such as Cr, Ni and Co.
We studied the preparation of ultla pure iron by an organic refining method in order to over-come the barrier underlying in conventional inorganic processes. This new method is based on the chemistry of organometallic compounds. Its operating principle is that a stable organometallic iron compound is synthesized with pure iron, refined by various organic refining processes and its refined product is decomposed by the use of a special reagent under a certain condition in order to obtain ultra pure iron. What is most important in this process is the selection of proper organometallic compounds. We investigated metallocene and β-diketone metal chelate. Especially, since β-diketone metal chelate greatly differs in stability against a reagent and the formation and the decomposition rate and is easily synthesized, we chose acetylacetone iron chelate as the key substance. By finding a new decomposition reaction with hydrazine derivative, we successfully produced ultra pure iron with metallic impurities much lower than those in the purest iron obtained by the inorganic processes.
This method which enables the preparation of iron of ultra purity may be expected to make great contributions to research on the properties of iron and steel. Studies on its semi-indusdrial applications are now in progress.View full abstractDownload PDF (749K) -
Tadashi Sawatani, Keiichi Tanigawa, Hisao Ochi, Hiroshi Mimura, Kiichi ...1974 Volume 38 Issue 12 Pages 1137-1143
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSExploratory work has been carried out to produce pure iron by the application of organic processes in place of the inorganic methods hitherto used in reducing impurities in iron.
The outline of the new method is as follows: Iron salt refined previously by an ion association solvent is used as the starting material. When the iron salt is allowed to react with a β-diketone compound under a proper condition, β-dicarbonyl iron chelate of high purity is obtained. The product is further refined by the recrystallization method, and chelate of extremely high purity is produced. When this chelate is decomposed by hydrazine derivatives under an appropriate reaction condition, a high-purity iron oxide is obtained. By reducing this oxide with hydrogen, a high-purity iron powder is obtained. An ultra pure iron rod more than 99.99% is obtained by the treatment of the compact of this powder with zone refining. The final sample is analyzed by an improved method of chemical analysis, vacuum fusion, internal friction, and mass spectrometry. It is ascertained that the present new method can very effectively remove metallic impurities such as Cr, Ni and Co in iron and the produced iron surpasses in purity all of commercially available pure irons. This is also verified from the measurement of the ratio of electrical conductivity at room temperature to liquid helium temperature.
Recently, the dependence of flow stress on strain rate has been investigated by many authors to clarify the effect of plastic deformation in iron. Therfore, it is of interest to study the effect of purity on the strain rate sensitivity. The present ultra pure iron is used for this purpose in comparison with vacuum melted electrolytic iron, i.e. ordinary pure iron. It is found that there is a noticeable difference in strain rate sensitivity of flow stress between the present ultra pure iron and the ordinary one, and the present one shows a higher strain rate sensitivity of flow stress in the low strain rate region.View full abstractDownload PDF (639K) -
Tetsuji Noda, Norio Sato1974 Volume 38 Issue 12 Pages 1143-1149
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe anodic passivity-maintaining current of iron in acidic sodium phosphate solutions of pH 1 to 6 has been investigated as a function of the electric field in the passive film. The passive oxide film in acid solutions consists of a γ-Fe2O3 layer with an outermost hydrous oxide layer of negligible thickness and the overpotential produces a high electric field in the γ-Fe2O3 layer. At the steady state, the ionic current through the film, which is represented by the passivity-maintaining current, is equivalent to the dissolution rate of the film. It is shown that the ionic current depends on the electric field strength obeying a field-assisted ion migration mechanism. The self-diffusion coefficient and the apparent activation energy of ion migration are estimated for iron (III) and oxygen (II) ions and compared with the diffusion data in the literature. The oxygen ion that migrates in the film has a self-diffusion coefficient of 4.6×10−26 cm2 sec−1 at 25°C, its activation energy being approximately 11 kcal/mol.View full abstractDownload PDF (524K) -
Kimitaka Sato, Isamu Taguchi1974 Volume 38 Issue 12 Pages 1150-1154
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn investigation was undertaken to analyze vanadium carbide in the residues extracted from steel by means of infrared spectrometry. The results are summarized as follows: (1) Characteristic absorption bands in an infrared region were newly observed at 1090, 980, 810 and 640 cm−1 for the vanadium carbide extracted from steel and approximately identified as VC by X-ray diffraction. There were, however, cases where the absorption bands were not observed. We found that the cause was primarily due to the composition of particle sizes of the extracted vanadium carbides from an electron microscopic observation. (2) The effects of the particle size is observed for synthesized vanadium carbides identified approximately as VC in the manner as observed for the extracted vanadium carbide. Absorption bands were found only for the particle of sizes less than 2 μm. Oxides of vanadium may be, however, involved in a commercial vanadium carbide to a level undetectable by X-ray diffraction, so that it is now not clear whether the absorption band at 990 cm−1 originates or not in vanadium carbide. (3) A careful review of the relation between the crystal structure and the infrared spectrum of vanadium carbide extracted from steel revealed that the vanadium carbide may have a distorted structure of the NaCl type.View full abstractDownload PDF (510K) -
Takeo Murata, Yunoshin Imai1974 Volume 38 Issue 12 Pages 1154-1159
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe activation energy for transient creep by a differential test has been measured as follows. The temperature of the specimen is raised to the testing temperature in advance by a furnace placed outside a vacuum vessel. The heat necessary for raising the temperature of the specimen is instantly given by applying half a cycle of a very large alternating current (1400 A) of 50 Hz to the specimen, and a small current is applied so as to keep the temperature constant. This procedure make it possible to raise the temperature of specimens with a cross section of 2×10 mm2 by about 5°C for 10 ms. The activation energy for the transient creep of alpha iron obtained at 700°C shows a higher value than that for self-diffusion when the creep strain is nearly zero and decreases rapidly to a minimum value (first region). Then the value increases to a peak value (second region) and decreases again gradually to that for steady-state creep (third region) as the creep strain increases. The first and second regions are observed below the creep strain of about 3%. The phenomenon is also observed in Fe-19Cr alloy. Accordingly, it is thought that the rate controlling process of the transient creep is not such a simple one as those proposed so far but a complex one which may be composed of several stages.View full abstractDownload PDF (528K) -
Takeo Murata, Yunoshin Imai1974 Volume 38 Issue 12 Pages 1160-1165
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe transient creep characteristics of polycrystalline alpha iron were investigated mainly at temperatures ranging from 500 to 650°C using the constant stress creep equipment with a servo divider and the rapid heating method developed newly for determining the activation energy for transient creep. The results obtained are summarized as follows: (1) The transient creep strain exhibits a normal time dependence and inverted transient creep has not been observed. The stress dependence of the initial creep rate, Vi, which is the rate just after applying a load is larger than that of the steady-state creep rate, Vs, and the value of Vi⁄Vs increases as the stress increases within the range up to about twice the 0.01% offset stress. (2) Of some proposed equations for creep-time relation, an equation based on the assumption given by Akulov satisfies the experimental results fairly well. The calculated values of the creep rate approximate the experimental ones at the creep strain more than 1%. (3) The activation energy for transient creep depends on the creep strain. The dependence will be divided into three regions at 700°C as reported previously. However, the first region is not observed at 800°C, and the values of the activation energy obtained at the creep strain of nearly zero are smaller than that of self-diffusion on the contrary to the results at 700°C.View full abstractDownload PDF (466K) -
Tomoo Suzuki, Masuo Hagiwara1974 Volume 38 Issue 12 Pages 1166-1171
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe transition temperatures of the CsCl-type order-disorder transition of VMn alloys in the bcc range have been determined from specific heat measurements and differential thermal analysis. The lattice constants of VMn alloys with 0∼75 at%Mn have also been measured. The results obtained are summarized as follows:
(1) The critical temperature of the CsCl-type order-disorder transition is found to be 845°C for an equiatomic composition and decreases paraborically as the composition deviates from the stoichiometry.
(2) In the specific heat curve of an equiatomic VMn alloy, an anomalous peak corresponding to the so-called 550°C anomaly in FeCo alloy is also observed at about 730°C, and this anomaly is named as “730°C anomaly”. The temperature of this anomaly is almost constant for the V-rich alloy and decreases rapidly with the increase of Mn content.
(3) The lattice constants of bcc VMn alloys are smaller in the ordered state than the disordered state; a decrease of at least 0.6% in the lattice constant is observed for an equiatomic alloy upon ordering.
(4) The lattice constants of the bcc VMn solid solution quenched from 1050°C show a large negative deviation from Vegard’s law.View full abstractDownload PDF (548K) -
Masuo Hagiwara, Tomoo Suzuki1974 Volume 38 Issue 12 Pages 1172-1178
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe ordering and disordering processes in δ-VMn alloys which form the CsCl-type superlattice have been investigated by measurements of thermal expansion, lattice constants and hardness. The results obtained are summarized as follows:
(1) A remarkable increase in the lattice constant with disordering is also confirmed from dilatometry. The change in thermal expansion coefficient of the equiatomic VMn alloy with temperature is quite analogous to the specific heat curve; an anomalous peak at about 730°C is also observed in this case.
(2) Thermal expansion coefficients between 300 and 600°C are larger in the disordered state than the ordered state. Since the thermal expansion coefficients between Tc and 950°C are extremely high in the vicinity of the equiatomic composition, it is be concluded that there are short range order in this range of composition and temperature.
(3) Remarkable solution hardening is observed in the bcc VMn solid solution. However, the ordered VMn alloys show minimum hardness at the equiatomic composition.
(4) The VMn alloy exhibits a peak in hardness at temperatures slightly below the critical temperature in a similar way to many other superlattice alloys.
(5) Isothermal ordering proceeds intermittently with two times of retardation. It is observed that the half-width of diffraction lines increases to show the existence of the micro-strain during a rapid change in the degree of order, and also the hardness increases during the retardation of order.View full abstractDownload PDF (633K) -
Koji Tanoue, Yasuhisa Aono, Kenji Senba, Kenji Okazaki1974 Volume 38 Issue 12 Pages 1178-1185
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSLow temperature deformation of powder metallurgical pure Mo and dilute Mo-Cr, Mo-W alloys are studied over the temperature range from 77 to 500°K by simple tension, stress relaxation and incremental unloading tests. The experimental results show that substitutional solute atoms do not affect the activation volume V* and the thermal component of the flow stress σ*, but affect flow stress σ through the athermal component σμ. From the relation Hk=4τ*V*, the kink energy Hk is calculated to be 0.58 eV both for pure Mo and Mo alloys. The activation energy H is deduced to be 1.40 eV at 500°K, which is in good agreement with 1.48 eV obtained from Seeger’s equation proposed for the Peierls-Nabarro process at low stress. It is concluded from the present results that low temperature deformation (T<500°K) is controlled by the overcoming of Peierls-Nabaroo hills by the nucleation of double kinks and that substitutional solute atoms increase only the athermal component of the flow stress.View full abstractDownload PDF (598K) -
Susumu Ikeno, Shigeoki Saji, Shigenori Hori1974 Volume 38 Issue 12 Pages 1186-1191
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPreviously we reported on the changes of aspects of matrix precipitates in Cu-0.5, 1.0, 1.3, 2.0 and 4.0%Ti alloys. In this paper, we studied on precipitation due to grain boundary reaction with the same alloys. The results are summarized as follows:
(1) Cellular precipitates are observed in higher Ti content alloys, and grain-boundary precipitates attend with PFZ are observed in lower Ti content alloys at the same aging temperature.
(2) Width of PFZ observed in Cu-1%Ti alloys during aging at 450∼550°C, becomes narrower with aging time and then broader again with preferential growth of grain-boundary precipitates.
(3) Nucleation sites of the cellular precipitates are considered to be the grain boundary surface in 4%Ti alloys and grain boundary edge in 2%Ti alloys in the aging at 450°C by the thory of Cahn. Activation energy for growth of cellular precipitates is about 30 kcal/mol for both alloys.View full abstractDownload PDF (1086K)
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