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Volume 28, Issue 8
Displaying 1-14 of 14 articles from this issue
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Imao Tamura, Hirofumi Yoshimura, Masao Ibaraki, Masayoshi Tagaya1964 Volume 28 Issue 8 Pages 433-438
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe tempering behavior of martensite in an ausformed Fe-27.56%Ni-0.44%C alloy was examined by means of microhardness tests, optical microscopy and transmission electron microscopy. The tempered martensite in the ausformed specimen showed a higher hardness than the non-ausformed throughout the range of tempering temperatures, and maintained a higher hardness level up to higher temperatures than that of the non-ausformed. The tempered martensite in the ausformed specimen was less etched with nital than that in the non-ausfomed. The transmission electron micrographs showed that the ausformed martensite had a dense, cloudy distribution of dislocations. The carbide precipitated at the dislocations and also on the twin faults. The precipitated carbides hardly grew at the dislocations but grew on the twin faults. The carbide precipitation and its growth on the twin faults in the ausformed martensite were depressed and delayed during tempering due to the presence of dense dislocations.View full abstractDownload PDF (1174K) -
Seita Sakui, Tsutomu Mori, Tsutomu Kakuma1964 Volume 28 Issue 8 Pages 439-442
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe dynamic tensile tests with strain rate 37/sec was performed at −196°C to 130°C for aluminum-magnesium alloys (0.93, 1.82 and 3.67%Mg) with the use of the apparatus of drop hammer type which was described in a previous paper. The results obtained were as follows:
(1) The dynamic test resulted in a larger tensile strength than the static test, and the lower testing temperature increased the difference in tensile strength by the dynamic and static tests.
(2) In the dynamic test the elongation seemed to increase with temperature, while the static test showed the minimum elongation around room temperature.
(3) The dynamic test gave a larger flow stress than the static test and it was concluded that the larger flow stress observed in the dynamic test was due to the strain rate dependence of flow stress and the change of the internal structure of the specimen in the dynamic test which was different from that obtained by the static test.View full abstractDownload PDF (1210K) -
Seita Sakui, Tsutomu Mori1964 Volume 28 Issue 8 Pages 443-447
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFrom the lower yield stress measured by the static and dynamic tensile tests with a strain rate of 30/sec at room temperature and −78°C, the effect of the temperature and the strain rate on ky and σi of the Petch equation, σy=σi+kyd−1⁄2, was studied. The specimens used were the vacuum melted iron with 0.013%C and 0.001%N and the decarburized iron with less than 1 ppm C and N. The results obtained were as follows:
(1) The strain rate and the temperature dependence of the lower yield stress of iron were dependent entirely on those of the frictional stress σi.
(2) σi and its temperature and the strain rate dependence did not depend on the carbon and nitrogen contents of the specimen in the range from several hundred to 1 ppm.
(3) From the above result (2) and the fact that the activation volume, which was calculated from the strain rate dependence of σi, was 10∼20 b3, it was concluded that the Peierls-Nabarro stress would be considerably large in iron.
(4) The effect of the carbon and nitrogen contents on the yield glide elongation was also studied and it was shown that iron had a distinct yield phenomenon even if the carbon and nitrogen content was less than 1 ppm.View full abstractDownload PDF (1867K) -
Sadao Sano, Hiroshi Matsui, Ryozo Nakagawa1964 Volume 28 Issue 8 Pages 448-451
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUsing ARL’s 1.5 m quantometer, analyses of magnesium metals and its alloys have been carried out by the point-to-plane method.
In magnesium metals, when low voltage spark (L=360 μH, C=60 μF, R=50 Ω, V=940 V) is used for excitation and the sample polarity is negative, the analytical results are obtained successfully.
In magnesium alloys, when high voltage spark(L=360 μH, C=0.007 μF, R=residual, V=20 kV) is used for excitation, the analytical results are obtained successfully.
Analysed elements and concentration ranges are Al 0.04∼0.22% and 5.3∼10.3%, Cu 0.006∼0.2%, Fe 0.004∼0.03%, Mn 0.01∼0.3%, Ni 0.0006∼0.03%, Pb 0.006∼0.13%, Si 0.01∼0.44%, Sn 0.005∼0.13%, and Zn 0.001∼0.15% and 0.11∼3.5%, and these elements are determinable with a coefficient of variation of about 1∼5%.View full abstractDownload PDF (428K) -
Isao Gokyu, Keijiro Suzuki1964 Volume 28 Issue 8 Pages 452-456
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt has been experimentally said that the drawability is better for the coarse-grained material. But it is doubtful that this principle can be applied to all cases. This principle can be applied to the case if the flow stress is higher for fine-grained material at low strains, and after sufficient strain the mechanical properties become the same for both fine and coarse grains. But this principle can not be applied if the flow stress at low and high strains is lower for coarse-grained material than fine-grained material. On the other hand, the component of directionality is a good indicator of drawability. So the drawability is also considered in terms of directionality. From these points of view, the investigations were done with 70-30 brass, 18-8 stainless and mild steel.
The drawability of 70-30 brass and 18-8 stainless, which have face centered cubic lattice, is dependent upon the grain size, while that of mild steel, which has body centered cubic lattice, is dependent upon the directionality rather than the grain size.View full abstractDownload PDF (1786K) -
Ichiro Morimoto, Hiroshi Maeda1964 Volume 28 Issue 8 Pages 457-460
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of chromium and molybdenum on the magnetic properties of high permeability iron-aluminum (13∼16%) alloys was studied. The magnetic properties were measured after heating at 1000°C in hydrogen atomosphere and water quenching from 600°C.
The results obtained are as follows:
(1) The addition of 2∼4% molybdenum improves greatly the magnetic properties of Fe-Al alloys. The aluminum content which is required to exhibit the most favorable magnetic properties proportionally decreases with the increasing molybdenum content. The values of μ0>6000, μm>100000 and Hc<0.03 Oe are obtained in a wide composition range from 14.3 to 15.8%Al and, in particular, the 3%Mo-14.6%Al-Fe alloy has the maximum values: μ0=8000, μm=120000, Hc=0.020 Oe.
(2) The addition of 1∼2% chromium slightly improves the magnetic properties, but 3∼4% chromium deteriorates.
(3) The saturation induction decreases with increasing chromium and molybdenum contents.
(4) Oil and air quenchings remarkably deteriorate the magnetic properties in all the specimens.View full abstractDownload PDF (1013K) -
Ichiro Morimoto, Hiroshi Maeda1964 Volume 28 Issue 8 Pages 461-464
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of molybdenum on the Fe3Al-FeAl phase transformation of Fe-Al alloys was studied by means of electrical resistivity measurement at high temperatures, and magnetic properties of the alloys under the various heat treatments were compared with the transformation process.
The results obtained are as follows:
(1) The transformation temperature from Fe3Al to FeAl phase increases at a rate of 17°∼18°C per molybdenum percent.
(2) The temperature coefficient of resistivity is negative at the FeAl phase, and its absolute value increases with increasing molybdenum content.
(3) The FeAl phase quenched in water sharply changes to the Fe3Al phase at a temperature around 250°C independent of the molybdenum content, and then the magnetic properties decrease.
(4) The FeAl phase increases with temperature in 400°C-transformation temperature regions in which both FeAl and Fe3Al phases exist, so that the magnetic properties increase with temperature. The best is obtained in water-quenching from temperature above the transformation in case of 0% molybdenum, but from temperature about 50°C below it in case of 3∼4%. More than 80% of the maximum value are obtained in water-quenching between 500° and 600°C.
(5) The magnetic properties remarkably decrease due to the formation of the Fe3Al phase at a quenching temperature below 400°C in case of 0% molybdenum, but slightly decrease in case of 2∼4%. This is believed to depent on the change of magnetic anisotropy and magnetostriction with molybdenum.View full abstractDownload PDF (752K) -
Fumitoshi Nakamura, Seizo Saito, Kunio Okabayashi1964 Volume 28 Issue 8 Pages 465-470
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relation between vacuum degree and wear has been made clear in the range of the low frictional velocity, but that of the high frictional velocity is unknown.
This study has been carried out using a specimen of carbon steel in the range of 760∼2×10−5 mmHg. The frictional velocity is 400 rpm (1.63 m/sec) and 1200 rpm (4.89 m/sec), and the normal load is 1 kg.
The results obtained are as follows:
(1) In the velocity of 400 rpm, the wear loss in the range of 760∼1 mmHg decreases with the increase of vacuum degree. However, it becomes almost constant beyond a certain high vacuum degree.
(2) In the velocity of 1200 rpm, a seizure phenomenon was observed on the worn surface of the ring specimen and the wear loss of the rod specimen becomes the maximum at a vacuum of 10−1 mmHg.
(3) The hardened patches are more effective in the wear resistance than the oxide film at the wear surface.View full abstractDownload PDF (1366K) -
Takayuki Ôoka, Shoichi Matsuda, Hajime Komatsu1964 Volume 28 Issue 8 Pages 471-476
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe fine structure of martensite in plain carbon steels has been studied by transmission electron microscopy. In a 0.17%C steel most of martensites are free from internal twins but with dislocations of high density. While in a 0.87%C steel, the plate-like grain of martensite consists of fine internal twin bands together with dislocations of high density.
As regards the fine structure of the martensite tempered up to 300°C the main differences result from the substructure existing in the martensite state. In the 0.17%C steel, during tempering at 150°C, carbon atoms segregate around the dislocations and tiny metastable carbides precipitate in situ. With the increase of the tempering temperature up to 300°C the precipitation proceeds in the usual manner, producing a Widmanstätten arrangement of cementite. In the 0.87%C steel carbides precipitate along the twins by tempering at 150°C for 1 hour and by increasing the tempering time the other carbides can also be seen across the twins. At this stage, they were identified as ε-carbides by selected area electron diffraction. At high tempering temperatures the carbide was found to be cementite, the orientation relationships being
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The first of these is in agreement with the work of Pitsch and Schrader but the second is different from it.View full abstractDownload PDF (1158K) -
Osamu Izumi, Masao Iwamoto1964 Volume 28 Issue 8 Pages 476-482
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe changes in hardness, elastic modulus and bending deflection with the rolling reduction and low-temperature annealing of nickel silver were measured on the specimens cut out parallel and transverse to the rolling direction of the sheet. And the results were considered in relation to the rolled structure.
The anisotropies become more remarkable as the rolling reduction exceeds 50%, and in this region, the measured values are always higher in the transverse direction than in the parallel direction. Perhaps, this may be due to the development of the rolling texture in the face-centered cubic system and to the appearance of the flaw-like strain markings developed transverse to the rolling direction. The low-temperature annealing increases the values of hardness and elastic modulus to attain the maximum values at 350°C. Also, the greater the rolling reduction is, the higher the increasing ratio becomes. The change in hardness due to the low-temperature annealing is greater as the grain size reduces, wherease the change in elasticity is hardly affected by the grain size. The process of anneal-hardening at each temperature does not show the two-stage hardening which has been observed in the α-brass sheet, but follows a simple and smooth process.
No difference can be observed between the as cold-rolled and as anneal-hardened microstructures, although some structural changes of a kind of polygonization have been found in α-brass after low-temperature annealing. The results of bending deflection test correspond with those of elastic modulus.View full abstractDownload PDF (1344K) -
Noboru Makino, Yasuo Kimura, Masaki Suzuki1964 Volume 28 Issue 8 Pages 483-489
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWith the object of improving the properties of MnAl compound suitable for the application to permanent magnet, the effect of pulverizing and swaging on the magnetic properties of MnAl, especially on its coercive force, has been studied.
When MnAl is pulverized in a ball mill, IHC increases at the expense of Br. Pulverizing in a hammer mill produces a striking increase in IHC and after being pulverized 130 times in the mill, IHC reaches the highest value of 6500 Oe. The relation between IHC and grain size of the hammer milled MnAl powder shows close resemblance to those of Ba ferrite, MnBi and Fe3O4, but an increase in IHC takes place at far more coarse grains than in the case of these typical single domain magnets. Saturation magnetization Is, lowerd by hammer milling is recovered by tempering, and the increased IHC is reduced. The permanent magnet properties obtained are not sufficent to practical applications. Magnetic press was not recognized to be effective.
MnAl bars swaged at room temperature by the reduction of 86% and 71% improved IHC to be 4000 Oe and 3000 Oe respectively. Decrease in saturation magnetization by swaging was not observed. Saturation magnetization and maximum energy product of the swaged MnAl is raised by tempering. Swaging at 400°C gives the result inferior to room temperature swaging.
MnAl containing Ti, especially, the specimen having a high Is×IHC value (68.93%Mn, 28.16%Al, 1.94%Ti and 0.97%Cu) shows a remarkable increase in IHC and decrease in Is by swaging at room temperature. When tempered, this specimen acquires excellent permanent magnet properties. For example, the specimen swaged by 84% and tempered at 500°C for 1 hr has the following properties; Br=4840 gauss, IHC=3100 Oe, BHC=2400 Oe and (BH)max=4.5×106 gauss·Oe. This (BH)max value is higher than that obtained by Koch et al. with MnAl containing no additional element.
On the MnAl specimens containing Ti, swaged and tempered, the magnetic anisotropy energy derived from approach to saturation seems to be proportional to Is×IHC. This fact may give a suggestion on the mechanism of coercive force of swaged MnAl.View full abstractDownload PDF (1659K) -
Kinji Yokoyama, Tomoo Suzuki, Toshio Kano, Yasuo Tachi1964 Volume 28 Issue 8 Pages 489-494
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo investigate the effect of directionality on the quenching deformation of a low alloy tool steel (JIS SKS 3), the dimentional changes due to quenching and subsequent treatments were measured of the specimens forged at various forging ratios. Further, thermal dilatometric experiments and microscopic observation were carried out. The results are as follows. (1) There is no difference in quenching-deformation of as cast steels by the direction in which the specimens were cut out, but the linear expansion due to quenching was more marked in the transversal specimens of the steel forged at a forging ratio of 1.5 than the longitudinal ones. This shows that a slightly forged steel has directionality on quenching-deformation. (2) When the cylindrical specimens were quenched, they were deformed by the effect of the form of specimens and at the same time by the effect of directionality of the steel. The subsequent tempering or the sub-zero treatment does not change the ratio of length and diameter of the specimens. (3) The Ms point of the longitudinal specimen is 10°C lower than the transversal one. (4) The fibre structure of the steel consists of many fine layers containing alloying elements of different amounts, and the layers have different Ms points. It was concluded that anisotropy of the quenching-deformation of this steel depends on the above feature of the fibre structure.View full abstractDownload PDF (1107K) -
Teiichi Homma, Sadabumi Issiki1964 Volume 28 Issue 8 Pages 494-495
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (200K) -
Yoshihiro Tsunoda1964 Volume 28 Issue 8 Pages 495-496
Published: 1964
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (300K)
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