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Volume 44, Issue 12
Displaying 1-18 of 18 articles from this issue
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Masatoshi Sakamoto, Yunoshin Imai1980 Volume 44 Issue 12 Pages 1329-1336
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAging curves for the precipitation of Fe4N and Fe16N2 from α-iron were measured in a temperature range between 373 K and 623 K by internal friction technique, and effects of alloying elements (Co, Mo, Ni, W) on the precipitation process were studied. The results are discussed in terms of the C-curves for 50% precipitation of Fe4N and Fe16N2.
Experimental results are summarized as follows:
(1) The C-curve in an unalloyed iron depends on the concentration of nitrogen; the nose of the C-curve shifts to shorter times and higher temperatures as the nitrogen concentration increases.
(2) Precipitation of Fe4N. The addition of 0.8 and 1.2%W has no effect. The addition of Co and Mo shifts the upper part of the C-curve to the right, i.e., the precipitation is delayed, but has little effect on the lower part. The addition of Ni enhances the precipitation rate considerably. In an unalloyed iron, Fe4N precipitates only above 473 K, but in 4.7%Ni and 4.9%Co alloys it precipitates even at 423 K.
(3) Precipitation of Fe16N2. The addition of W shifts the whole C-curve to the right. Other alloying additions (Co, Mo, Ni) shift the upper part of the C-curves to the right and have little effect on the lower part. The effect of Co is the most pronounced.
(4) The upper part of the C-curve is related to the rate of precipitate nucleation, and it has been found to be affected by the alloying. The lower part, which is related to the diffusion of nitrogen, is not affected appreciably by the alloying. The diffusion rate of nitrogen is not affected by the alloying either. Hence, it is considered that the alloying affects the rate of nucleation. This effect is discussed in terms of the change in the solubilities of nitrides by the alloying; the change in the degree of supersaturation of nitrogen by the alloying is in a very good correlation with the change in the nucleation rate represented by the nose-time of C-curves.View full abstractDownload PDF (623K) -
Yoshitake Nishi, Nobutaro Kayama, Shoji Kiuchi, Kenji Suzuki, Tsuyoshi ...1980 Volume 44 Issue 12 Pages 1336-1341
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy use of the vibration technique, viscosities of Pd84Si16 alloy and Pd78Cu6Si16 alloy were measured over the temperature range from 1150 to 1500 K. The viscosity was represented by log(η⁄Pa·s)=4.21+2.53×103⁄T for Pd84Si16 alloy and log(η⁄Pa·s)=−4.23+3.51×103⁄T for Pd78Cu6Si16 alloy. The temperature dependence of the viscosity of undercooled liquid was estimated by using Cohen-Turnbull’s expression and if the viscosity at the glass transition temperature was of 1010 Pa·s, it was shown by log(η⁄Pa·s)=−3.42+8.58×102⁄(T−551) for Pd84Si16 alloy and log(η⁄Pa·s)=−3.23+1.33×103⁄(T−520) for Pd78Cu6Si16 alloy. Using these results, the T-T-T curves were calculated in the case of mechanism of homogenious nucleation and growth. The critical cooling rates obtained from these T-T-T curves coincided with the directly measured critical cooling rates, and it was concluded that the glass formation was affected mainly by the liquidus temperature and the viscosity of liquid. Finaly the effect of viscosity on glass formation was discussed from the standpoint of a cluster formation in liquid.View full abstractDownload PDF (476K) -
Yuji Muramatsu1980 Volume 44 Issue 12 Pages 1341-1349
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to produce high manganese steel by the powder metallurgical process, three kinds of Mn-containing powder, that is, electrolytic manganese powder, Fe-Mn alloy powder and Fe-Mn-C alloy powder were mixed with atomized iron powder together with graphite powder respectively, so as to make up alloys having chemical composition of 13% manganese and 1.18 or 1.30% carbon. These three kinds of mixed powder were compacted and sintered in hydrogen containing 0.3 vol% propane gas under the condition of experimented sintering temperature and time. The sintering behaviour of these powder mixes was investigated. The oxygen content and mechanical properties of sintered steels were examined. Experimental results indicated that the use of Fe-Mn-C alloy powder made it possible to obtain the sintered high manganese steels having lower oxygen content and more homogeneous structure at relatively low sintering temperature. The reason for this can be attributed to resistant characteristic of Fe-Mn-C alloy powder against oxidation and the formation of a liquid phase during sintering. It was concluded that the Fe-Mn-C alloy powders whose composition corresponds to those of commercial high carbon ferromanganese materials are considerably useful for the production of the sintered high manganese steel by powder metallurgical process.
The mechanical properties of these sintered steels are markedly improved with densification. The sinter-forging process is an effective and promissing process for the densification of these sintered steels.View full abstractDownload PDF (1159K) -
Yuji Muramatsu1980 Volume 44 Issue 12 Pages 1350-1356
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSintered high manganese steels were produced by the admix-method and they were densified by sinter-forging. The mechanical properties, especially tensile strength, elongation and impact strength of these highly densified steels were examined as a function of manganese or carbon content. The effect of particle size of iron powder and austenitizing temperature on these mechanical properties were also examined.
The results obtained are summarized as follows:
(1) The optimum manganese content determined from the view points of mechanical properties and manufacturing process is about 16%.
(2) The tensile strength and elongation of sinter-forged steels are not influenced so much by the sintering conditions employed in this experiment, but their impact strength is considerably affected by the sintering conditions, and the higher the sintering temperature and the longer the sintering time, the higher the impact strength.
(3) In case of the sinter-forged high manganese steels containing 16% manganese, the addition of 1.0% carbon is sufficient for tensile properties, whereas for impact properties together with tensile properties an addition over 1.3% is desirable.
(4) The particle size of iron powder has an influence on the mechanical properties, particularly on the impact strength of sintered alloy. It has also a remarkable influence on the microstructure of sinter-forged steel, and the use of finer iron powder is favorable to produce homogeneous austenitic structure.
(5) The high temperature austenitizing (>1420 K) is effective to the increase of impact strength. However, in case the successive quenching is applied on the material, it is undesirable because such a combination of heat treatment causes the deformation of the material.View full abstractDownload PDF (1177K) -
Naotsugu Inakazu, Hisashi Yamamoto1980 Volume 44 Issue 12 Pages 1356-1361
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to study the forming process of the deformation band developed in the periphery of a copper single crystal rod during drawing, the behavior of the peripheral region was investigated by determining the pole figure.
The deformation banding mechanism in the peripheral region of wire rod was different from that in the central region, that is, no matter how the initial orientation may be, the end orientation was accompanied by the {111}⟨112⟩ component and simultaneously by the twin component.
It was assumed that the shearing force acted on the periphery of a drawn wire rod during drawing, because of the friction between a die and material.
At the first stage of deformation, the cube structure was developed by the {100} slip rotation in the {100}⟨110⟩ slip system rather than the {111}⟨110⟩ slip system, and at the second stage, the {111}⟨112⟩ component was developed by the {111} slip rotation around the circumferential axis, because of the inclination of the {111} plane to become parallel to the compressive plane of the drawn wire rod, and at the same time the twin component was developed by the inverse rotation around the circumferential axis.
Consequently the deformation bands which resembled in appearance annual rings of a tree were developed at the peripheral region.View full abstractDownload PDF (556K) -
Tokuhiko Nishida, Kiyoshi Tamura1980 Volume 44 Issue 12 Pages 1362-1369
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to strengthen the sintered iron powder compacts by precipitation of vanadium carbide V4C3, we studied the sintering process of compacts mixed with vanadium, manganese and graphite powders, and the relation between tensile properties of sintered compacts and morphology of vanadium carbides. The results obtained are as follows: (1) Tensile strength of sintered compacts increases as the amount of fine vanadium carbides increases, which precipitate in primary ferrite during cooling after sintering. (2) Sintered compacts are strengthened markedly by the simultaneous addition of manganese and vanadium, which makes the precipitates of V4C3 finer and promotes sintering. High strength level of 650 MPa is achieved in 0.2%C-1.2%Mn-1.0%V-Fe compact cooled at the rate of 1.17 K/s after sintering at 1473 K. (3) Solution of V atoms in iron powder starts at lower temperature as vanadium powders are finer, and granular instead of flaky.View full abstractDownload PDF (1386K) -
Osamu Okuno, Ishi Miura1980 Volume 44 Issue 12 Pages 1370-1377
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDuctile fracture analysis by Monte Carlo simulation is carried out for square model that contains randomly distributed voids under uniaxial tension. It is assumed that the coalescence of voids is the results of internal necking or shear crack between voids. Ductile fracture strain and surfaces are computed. The following results are obtained. (1) The coalescence between adjascent voids occurs by internal necking. The coalescent mechanism between comparatively remote voids is shear crack. Predicted fracture surfaces are coincident well with observed one. (2) At high volume fraction of voids, internal necking occurs predominantly. And decrease the volume fraction of voids, shear crack increases. (3) On the first stage of flow, internal necking tends to occur. On the latter stage of flow, shear crack occurs frequently. (4) Relation between ductile fracture strains and volume fraction of voids is in good agreement with the experimental results for copper dispersion alloys by Edelson and Baldwin.View full abstractDownload PDF (538K) -
Tadashi Igarashi, Mitsuo Osada1980 Volume 44 Issue 12 Pages 1377-1384
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAg-Ni alloys containing fibrous Ni phase of 15∼40 mass% prepared by drawing of sintered alloys were oxidized at 923 to 1073 K in air. The depth of the internally oxidized layer, ξ, was measured and microstructures were observed in order to investigate the behavior of internal oxidation of two phase alloys.
The results obtained are as follows:
(1) The fibrous structure was disintegrated during internal oxidation, when the specimens were oxidized in a direction parallel to fibrous Ni phase. In an alloy with NNi=0.55 (NNi means mole fraction of Ni), cell-structure of oxide was formed.
(2) Oxides stretching in the direction of the fibrous structure of the alloy were dispersed in the alloy with NNi=0.245, while wavy lamellae of oxide were formed in the alloy with NNi=0.38, when specimens were oxidized in the direction of fibrous Ni phase.
(3) The relation between the depth of the internally oxidized layer and the oxidation time was shown by a parabolic law at every temperature with NNi=0.38. But the growth of internally oxidized layer with NNi=0.55 deviated from a parabolic law above 873 K.
(4) The parabolic rate constant of internal oxidation in a direction parallel to the fibrous structure, k\varparallel, was larger than that in a direction vertical to the fibrous structure, k⊥, at every temperature and in every Ni content.
(5) The permeability (product of oxygen content at the surface of an alloy and its diffusion coefficient) of oxygen in the internally oxidized layer was accelerated by the effect of the continuous interface of Ag and NiO extending in the direction of fibrous Ni phase, while it was disterved by the lamellae of oxide lying vertically to the oxidation direction.View full abstractDownload PDF (1009K) -
Toshiaki Yoneoka, Michio Yamawaki, Masayoshi Kanno1980 Volume 44 Issue 12 Pages 1384-1392
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSOxidation of pure vanadium has been investigated at temperatures of 723∼903 K and oxygen pressures of 1.33×103∼1.33×104 Pa by means of a thermo-electrobalance, an X-ray diffractometer, a Knoop hardness tester as well as metallographic techniques. The oxidation proceeded according to a parabolic rate law. The obtained parabolic rate constans scarcely exhibited pressure dependence. The activation energy for parabolic oxidation process was about 180 kJ/mol. The oxide scale on most specimens was composed of three layers of V2O5, V6O13 and VO2. These results were compared with those of the preceding study performed at lower oxygen pressures of 0.133∼133 Pa.View full abstractDownload PDF (926K) -
Takamichi Iida, Toshiya Kumada, Masaru Washio, Zen-ichiro Morita1980 Volume 44 Issue 12 Pages 1392-1397
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to determine the viscosity of liquid metals by the oscillating vessel method with high accuracy, an investigation was made on the corrections for the Roscoe’s absolute equation that connects the period and the logarithmic decrement of oscillations with the viscosity of liquid.
Corrections for the end effect were examined experimentally by the use of the cylindrical vessel of graphite. The values of the end correction for liquid metals such as Hg, Sn and Pb were obtained.
Corrections for the slipping effect were discussed on the basis of the corrected Roscoe’s equation which was previously proposed by the authors.
Furthermore, the relation between the correction factor ζ in the corrected Roscoe’s equation and the work of adhesion was also investigated experimentally.View full abstractDownload PDF (509K) -
Kazuaki Mino, Akira Ohtomo, Yoshinori Saiga1980 Volume 44 Issue 12 Pages 1397-1403
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Ni-22%Cr-12%Co-9%Mo-1%Al commercial alloy (Inconel 617) was oxidized in air at 1073 and 1173 K under tensile stresses to examine the effect of stressing on its high temperature oxidation. It was shown that the intergranular oxidation was significantly enhanced under the applied stress. The penetration depth increased with creep strain and oxidation time. A maximum depth of 200 μm was observed at 1173 K and at a creep strain of about 5% in 0.5Ms. In stress-free exposure tests the penetration depth was less than 10 μm. The enhanced intergranular oxidation was attributed to the localized fracture of external oxide layers and internal oxides of Al due to grain boundary sliding.
Abrasion of the specimen surface by a 100 grit SiC paper reduced the acceleration of the intergranular oxidation. The abrasion deformed surface recrystallized at the oxidation temperature and formed a fine-grained layer. The displacement at the individual grain boundary in this fine-grained layer was so small that the step height at the surface was decreased. This is believed to be the main cause of reduced intergranular oxidation at the abraded surface.View full abstractDownload PDF (1363K) -
Shotaro Morozumi, Michio Kikuchi, Shinzo Sugai, Masaaki Hayashi1980 Volume 44 Issue 12 Pages 1404-1413
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDiffusion couples of molybdenum with carbon and several carbides, i.e. B4C, SiC, TiC, and TaC, respectively, were heated for up to 3.6×105 s at various temperatures ranging from 1373 to 2223 K. The couples were then examined for composition, growth rate, structure, and hardness of reaction layers. Main results obtained are as follows:
(1) In the Mo-C system, only Mo2C layer was formed at below 1873 K, while two sub-layers consisted of Mo2C and η (MoC1−x), respectively, were found at above 1873 K. The activation energy for growth of total layer was 374 kJ/mol.
(2) In the Mo-B4C system, two sub-layers consisted of Mo2B and MoB, respectively, with dispersed carbon particles were formed.
(3) In the Mo-SiC system, Mo2C layer, including η (MoC1−x) phase at high temperature, mixture of Mo2C and Mo3Si2 phases, and Mo3Si2 phase in order from the Mo side were formed. The activation energy for growth of total layer was 477 kJ/mol.
(4) In the Mo-TiC system, two kinds of TiC in point of view of free carbon content were used; one is with 0.2% free carbon and the other is with 0.01%. In the Mo-TiC with 0.2% free carbon system, two sub-layers, i.e. relatively thick Mo2C layer and thin (Ti, Mo)C layer, were formed, while in the Mo-TiC with 0.01% free carbon system two thin sub-layers, Mo2C and (Ti, Mo)C, were formed; the Mo2C layer in the latter case was very thin and was not found after short time heating at low temperature. The activation energy for growth of Mo2C layer in the former system was 393 kJ/mol.
(5) In the Mo-TaC with 0.02% free carbon system, two thin sub-layers, (Mo, Ta)2C and (Ta, Mo)C, were observed.
(6) TEM studies on the interface between Mo(bcc) and Mo2C(hcp) showed that there was the following orientation relation, called as the Burgers relation, between these two phases; {110}Mo\varparallel(0001)Mo2C, ⟨111⟩Mo\varparallel⟨11\bar20⟩Mo2C.View full abstractDownload PDF (2170K) -
Kenji Morii, Yutaka Nakayama1980 Volume 44 Issue 12 Pages 1414-1421
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTexture developments and deformation structures have been investigated in silver poly-crystals rolled at the temperatures between 293 and 473 K. In the specimens rolled at 293 K an alloy type texture develops and shear bands occur in the grains deformed by mechanical twinning, while in those rolled at 423 K a pure metal type texture appears and the shear bands are scarcely formed so that deformation by multiple slip is activated in each grain. Both of the textures are explained in terms of the effects of shear banding on the development of rolling texture. It is concluded that the texture transition from the alloy type to the pure metal type can be explained by the diminution of mechanical twinning followed by shear banding with increasing rolling temperature.View full abstractDownload PDF (1719K) -
Nobutoshi Maruyama, Shiro Ban-ya1980 Volume 44 Issue 12 Pages 1422-1431
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe activities in Liquid Fe-Cu, Fe-Cr and Fe-Sn alloys have been determined by a modified transportation method at 1873 K. The activity coefficients can be calculated by a graphical integration of the following equation using the concentration ratios of the components in vapor and metal phases:
(This article is not displayable. Please see full text pdf.)
\ oindentwhere Ni and Xi are the mole fraction of the component i in the metal and vapor phases, respectively.
In the Fe-Cu system, the activities of iron and copper were found to be largely positive deviations from Raoult’s law over the entire composition range, and the activity coefficients of iron and copper at 1873 K are expressed by the following equations, respectively:
(This article is not displayable. Please see full text pdf.)
In the Fe-Cr system, the activities of iron show slightly negative deviations from Raoult’s law, with nearly ideal behavior, and the other component, chromium, shows negative behavior and that approximately obeys Henry’s law in the experimental composition range, NCr=0.079−0.508. The activity coefficients of iron and chromium at 1873 K are expressed by the following equations, respectively:
(This article is not displayable. Please see full text pdf.)
In the investigation of Fe-Sn system, the miscibility limit at 1873 K was determined from the phase diagram of Hansen. Activities of both iron and tin show largely positive deviations from Raoult’s law over the entire composition range.View full abstractDownload PDF (731K) -
Yasumasa Koyama, Toshiyasu Ukena, Osamu Nittono1980 Volume 44 Issue 12 Pages 1431-1439
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe α1(fct, c⁄a>1)\ ightleftarrowsα2(fct, c⁄a<1) and α2(fct, c⁄a<1)\ ightleftarrowsβ(fcc) phase transformations and the shape memory effect in indium-rich lead alloys have been studied by means of X-ray diffractometry supplemented by metallographic observations. The alloys containing 12∼15 at% lead transform from the α2(fct) phase to the α1(fct) phase by way of an intermediate phase (m phase) on cooling. The results of X-ray diffraction show that the metastable intermediate phase is observed both on cooling and heating, and has a face-centered orthorhombic (fco) structure. It is concluded that the α1\ ightleftarrowsalpha2 transformation is expressed by the α1\ ightleftharpoonsm\ ightleftharpoonsα2 transformation both on usual cooling and heating with the rate more than 8×10−3 K/s. The alloys containing 30∼36 at% lead transform from the β(fcc) phase to the α2(fct) phase on cooling. Surfaces of these m- and α2-phase alloys show a banded structure (surface relief) due to {110} transformation twinning, and the banded structure disappears above the transformation temperature. The m\ ightleftharpoonsα2 and α2\ ightleftharpoonsβ transformations take place with a mechanism involving macroscopic shear and are of diffusionless (martensitic) type. The temperature hysteresis in the two transformations is 10∼13 K between the heating and cooling transformations. The mechanism of these phase transformations is discussed in terms of the soft phonon mode, considering the double shear mechanism. A remarkable shape memory effect is observed in the reverse transformation on heating. The features of the shape memory behavior are presented and the mechanism of the shape memory effect is also discussed on the basis of the crystallographic reversibility of these transformations.View full abstractDownload PDF (1093K) -
Hideki Hagi, Yasunori Hayashi, Namio Ohtani1980 Volume 44 Issue 12 Pages 1440-1447
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to study the effect of hydrogen on the mechanical properties of electrolytic iron, creep tests during cathodic polarization have been carried out. On supplying cathodic current, the specimen yields to creep and the creep rate rises, but the creep stops after a certain time even when the hydrogen charging is continued. If the charging current is cut off during the creeping of the specimen, the creep rate rapidly diminishes; the creep induced by hydrogen charging stops in spite of the existence of dissolved hydrogen. Cathodic polarization introduces hydrogen into the specimen, and also causes internal damage on the specimen due to hydrogen precipitation. If the cause of the hydrogen induced creep is the increase of the mobility of dislocations being influenced by dissolved hydrogen, the creep strain increases as long as the cathodic current flows and the creep deformation progresses in the presence of dissolved hydrogen even when the charging current is cut off. These do not correspond to the results obtained in the present work. Therefore, the main cause of the hydrogen induced creep found in the present study is not considered to be the increase of the dislocation mobility, but it is the increase of dislocation density caused by hydrogen precipitation.View full abstractDownload PDF (873K) -
Hiroshi Tanaka, Kazunari Yoshida1980 Volume 44 Issue 12 Pages 1448-1449
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (382K) -
Shigeru Asano, Kaoru Yamaguchi1980 Volume 44 Issue 12 Pages 1450-1451
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (168K)
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