All issues
Volume 36, Issue 2
Displaying 1-13 of 13 articles from this issue
- |<
- <
- 1
- >
- >|
-
Ken-ichi Hirano, Hitoshi Hori1972 Volume 36 Issue 2 Pages 97-104
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe solvus curve of the G.P. zones in Al-Zn alloys has been determined by specific heat and electrical resistivity measurements.
By specific heat measurements, the reversion temperature for the G.P. zones has been determined to deduce the highest temperature for the G.P. zones to exist. It has been found that for a constant aging temperature the reversion temperature rises with aging time and finally becomes a constant temperature which depends on the aging temperature.
The electrical resistivity has been measured continuously during the cooling and heating of the specimen between the α phase region and room temperature. It has been found that, once the G.P. zones are formed, the electrical resistivity becomes higher than the value of homogenuous solid solution. The temperature for the initiation of G.P. zone formation during cooling coincides quite well with the highest temperature at which the G.P. zones are stable as determined by specific heat measurements.
The solvus temperature for the G.P. zones thus determined does not coincide with the previous results by other workers. The present results show that the solvus of the G.P. zones is located above the metastable α-α′ miscibility gap extraporated from the high temperature region where the α′ phase is stable. Further, it has been shown that the solvus of the G.P. zones in the concentrated alloys is also located above the stable α-α′ miscibility gap.
The present results suggest that the G.P. zones in this alloy are coherent precipitates of the α′ phase with a limited particle size.View full abstractDownload PDF (2847K) -
Yûkichi Kosaka1972 Volume 36 Issue 2 Pages 105-112
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe solidification behavior in Fe-C-Si alloys severely undercooled has been studied by using the isothermal solidification technique and a new type of solidification process has been found.
This type of solidification process is a non-eutectic reaction, the product of which is the compact graphite similar to the so-called temper carbon.
It is noteworthy that the temper carbon is the graphitization product of the cementite-eutectic, while this type of compact graphite obtained in the present experiment is formed prior to the cementite-eutectic reaction.
It follows from metallographic observations on the structure of samples quenched at various stages during isothermal solidification that in the solidification process which has been termed as “K-type non-eutectic reaction”, modified graphite nodules which may develop in the melt as non-equilibrium phase are immediately surrounded by austenite, so that their further growth results from the diffusion of carbon through austenite shells from the carbon-rich melt.View full abstractDownload PDF (3632K) -
Kiyoshi Aoki, Osamu Izumi1972 Volume 36 Issue 2 Pages 113-118
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTensile tests were performed on β-brass at room temperature ∼500°C and at the strain rate of 4.4×10−5∼2.2×10−2 sec−1. Mechanical properties varied markedly and non-monotonously with testing temperature and strain rate as follows: With increasing temperature, the yield stress once increases and then decreases, resulting in the formation of a peak of yield stress in the range of intermediate temperature. With increasing strain rate, this peak shifts to a higher temperature and the peak value increases. The strain rate dependence of yield stress is small below the temperature of this peak, but it becomes larger above that temperature. In the temperature range where the yield stress increases anomalously with elevating temperature, that is, the range below the temperature of the peak, the yield stress changes with the strain rate in a usual manner; the greater the rate, the higher becomes the stress. On the other hand, above this temperature, the yield stress shows a normal dependence on both temperature and strain rate. Among the various strengthening mechanisms of the ordered alloys, Brown’s model seems to be most favorable to explain the pronounced anomalous temperature dependence of yield stress.View full abstractDownload PDF (2447K) -
Yoshihira Okanda, Hiroshi Yamamoto, Kanemasa Maebuchi, Jun Beppu, Soji ...1972 Volume 36 Issue 2 Pages 119-125
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is known that fire grid materials used in an incinerator are worn by a strong corrosive action of combustion gases. In order to obtain useful metallurgical information about the deterioration for improving materials, detailed examinations were made on heat-resisting steels JIS-SCH 11 (25 wt%Cr, 4 wt%Ni, rest Fe) and JIS-SCH 13 (25 wt%Cr, 12 wt%Ni, rest Fe) that had been put into service as fire grid materials for 6∼10 months in a temperature range of 700°∼1000°C, using various techniques such as optical microscopy, EPMA, chemical analysis, X-ray diffraction and hardness tests. The experimental results obtained are as follows:
(1) S and Cl were detected in rust layers of both steels SCH 11 and SCH 13. From chemical analyses of the rusts, Ni/Cr ratios were found to be 0.3 for rust of SCH 11 and 1.3 for that of SCH 13.
(2) In the case of SCH 13, precipitates of the sigma phase were observed along grain boundaries of austenite, besides which S and Cl were found to be enriched at grain boundaries near the surface.View full abstractDownload PDF (3750K) -
Masataka Sugiyama, Akira Sato, Tatsuichi Fukusako1972 Volume 36 Issue 2 Pages 126-131
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSProperties of 2S Al and Al-Mn alloy sheets prepared by the process of direct-rolling of molten metals were investigated, and effects of direct-rolling conditions and soaking on them were studied. The main results obtained were as follows:
(1) The annealed sheets with excellent mechanical properties were obtained from fine grain direct-rolled plates whose supersaturated solute elements were precipitated.
(2) The soaking of direct-rolled plates increased the formability of their sheets and decreased the anisotropy of the sheets.
(3) As the direct-rolling speed became slower, the annealed sheets increased their formability, decreased 45° earing and promoted 90° earing. That was explained from the recrystallization texture {110}⟨001⟩ and {hk0}⟨001⟩.View full abstractDownload PDF (2332K) -
Kenji Matuki, Masao Yamada1972 Volume 36 Issue 2 Pages 132-138
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe aging characteristics of a Zn-0.04 wt%Mg alloy, mainly of the specimens cold rolled after quenching, were investigated by means of hardness and electrical resistivity measurements and electron microscopic observations. The main results obtained are as follows:
(1) Age hardening of this alloy was accelerated by cold rolling after quenching and increased with the amounts of reduction up to about 50%.
(2) In an early stage of isothermal aging in the temperature range between 30° and 90°C, the increase in hardness and resistivity was found in the specimens 70% cold rolled after quenching or furnace cooling. Two peaks which take place for the quenched specimens by room-temperature aging are shown at the same aging times in the hardness- and resistivity-aging time curves, while in the furnace cooled specimens only a single peak occurs at the same aging time in both curves.
(3) The activation energy estimated from the hardness and the resistivity change was about 13.6 kcal/mol for the quenched specimen and about 16.5 kcal/mol for the specimen 70% cold rolled after quenching or furnace cooling, respectively. These values correspond approximately to the activation energy of vacancy migration for Zn.
(4) Preferential precipitation on the dislocations was observed together with the precipitation of dispersed particles in the matrix for the quenched specimens by electron microscopic observation. In the 70% cold rolled specimens a finer dispersed precipitation was observed.
(5) Age hardening of the quenched specimen was considered to occur by the atmosphere formation arising from the interaction between Mg atoms and dislocations and the Mg-rich zone nucleated uniformely in the matrix. By cold deformation the atmosphere formation was enhanced as the number of dislocations and vacancies increases with the amounts of reduction.View full abstractDownload PDF (2669K) -
Kyuya Nagasaki, Shiro Haruyama, Teruo Miyashita, Satoru Asawa1972 Volume 36 Issue 2 Pages 139-143
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe anodic behavior of Fe-Ti alloys (0.2∼7.5Ti wt%) was investigated in acidic (pH 3.50) and alkaline (pH 8.40) solutions by using an electronic potentiostat. The results are summarized as follows: (1) The potentiostatic transient current of the alloys decreased in reverse proportion to time in the passive region. (2) In α single phase alloys the Flade potential observed in the acidic solution shifted to the noble direction with increasing Ti content. As to α+TiFe2 alloys, however, they remained constant regardless of Ti content. Therefore it was concluded that the Flade potential of Fe-Ti alloys was controlled by the α matrix. (3) The anodic current in the passive range decreased with increasing Ti content in the acidic solution, while it increased in borate-boric acid solution. (4) Transpassive dissolution was observed at about 1100 mV (vs. S.C.E.). Especially in α+TiFe2 alloys, a sharp current increase was observed, due to a combined effect of the transpassive dissolution of the α matrix and the fall-off of TiFe2.View full abstractDownload PDF (2072K) -
Seiichi Ikeda, Shigeo Ohashi, Goro Ito1972 Volume 36 Issue 2 Pages 144-149
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe oxidation resistance of Fe-Al-Cr alloys containing 0.5% titanium and 0∼2% molybdenum in carbon dioxide at the temperature of 600°∼900°C under a pressure of 10 kg/cm2 were studied together with their mechanical properties.
The results were summarized as follows.
(1) The oxidation of Fe-Al-Cr alloys increased with increasing molybdenum contents and also with decreasing oxidation temperature.
(2) Remarkable oxidation was noted at the testing temperature of 600°C for the alloys containing 2% of molybdenum. This oxidation phenomenon is attributed to the formation of MoO3 in the oxide film and also to the occurence of internal oxidation of aluminum in the alloy.
(3) The room temperature tensile strength increased and elongation decreased as the molybdenum contents increased, but the lowing of tensile strength was observed when the molybdenum content exceed 1.5%.
(4) The creep rupture strength and high temperature strength of Fe-Al-Cr alloy was proved to be improved by the addition of 0.5% of molybdenum and 0.5% of titanium without sacrificing superior oxidation resistance which is the noticeable merit of the alloy.View full abstractDownload PDF (3089K) -
Masami Onishi, Yoshinori Wakamatu, Koichi Fukumoto, Manabu Sagara1972 Volume 36 Issue 2 Pages 150-156
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIron-zinc diffusion couples were annealed at temperatures from 320° to 412°C.
All the intermetallic phases in the iron-zinc system were observed in the diffusion zone, while the α solid solution of zinc in iron could not be detected in any specimens examined. The δ1 phase layer is composed of two parts: palisade and compact δ1 layers in the same manner as in the case of “Hot Dip Galvanizing”. At temperatures above 360°C the total width of both δ1 layers varies with time according to the parabolic rate law, but the growth of the palisade layer does not follow the rate law. It seems more likely that the material is transported through the palisade layer mainly along the grain boundary.
The activation energy for the growth of the total width of both δ1 layers is 21.2 kcal/mol, which is in good agreement with the activation energy for the δ1 phase layer growth obtained by Horstmann in his study on the reaction of solid iron with molten zinc.
Kirkendall markers exist always at the interface between the ζ and η(Zn) phases. Although this means that there is a one-sided diffusion of zinc to the iron, zinc penetration into grain boundary of the iron has not been detected. It appears that the intermetallic phases are formed in the interface between the iron and zinc disks at first and then zinc preferencially diffuses into the intermetallic phases.View full abstractDownload PDF (2118K) -
Mikio Obayashi, Motoyuki Nakamura, Noboru Komatsu1972 Volume 36 Issue 2 Pages 156-164
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt has already been recognized by many reserchers that the lead oxide (PbO) causes catastrophic corrosion of steels at high temperatures. But most of the studies dealt with the reactions in the molten state of PbO.
The present study was carried out on the effects of heating temperature and atmosphere on the high temperature corrosion of some heat resesting steels at temperatures below the melting point of PbO.
The experimental results are summarized as follows:
(1) The catastrophic corrosion of heat resisting steels caused by PbO occurred even at temperatures below the melting point of PbO in both air (an oxidizing atmosphere) and argon gas (an oxygen depleted atmosphere).
(2) PbO-corrosion resistance of 21-4N steel was excellent, followed by SUH 31B, 21-12N. SUH 3B and SUS 53B were least resistant.
(3) The X-ray diffraction data confirmed that the main components of the corrosion products were 5PbO·CrO3 and PbO·6Fe2O3. Metallic lead was also detected when the steels were heated in the presence of PbO in argon gas. These results show that when PbO is present, Cr+3 ions tend to be oxidized to a higher valence state of Cr+6, leading to the formation of higher complex oxides than Cr2O3.View full abstractDownload PDF (3459K) -
Tetsuo Matsumura, Naomi Kotani, Takeshi Goto1972 Volume 36 Issue 2 Pages 165-169
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe determination of major and minor elements in manganese ore was investigated in order to develop a rapid quantitative method for production control. Complexities of mineral composition and history of manganese ore require a universal method for analysis, for which the X-ray fluorescence analysis by the glass bead sample technique was considered as being most suitable. A powdered sample (1 g) with Na2B4O7 flux (15 g) was fused in Pt-5%Au crucible and the melt was casted into a graphite mould to form a glass bead. Analysis was carried out by irradiation of X-ray beam directly on the surface of a glass bead. The precision and accuracy of the method were comparable to those of the conventional chemical method. In this paper, the conditions of the preparation of a glass bead, such as the selection of the flux, the size and form of a graphite mould, the effect of the ratio of sample to flux on reproducibility and so on, were intensively investigated.View full abstractDownload PDF (1974K) -
Koichiro Osozawa, Yukishige Fukase, Kozo Yokota1972 Volume 36 Issue 2 Pages 170-175
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of less than one per cent of aluminum, titanium, vanadium, zirconium, niobium or uranium and heat treatment on the stress corrosion cracking (SCC) of 18Cr-20Ni or 18Cr-16Ni steel was investigated in boiling magnesium chloride solution at 151°C.
The results indicate that the above alloying elements have no appreciable influence on the SCC resistance of stable austenitic stainless steel if they do not form nitride or carbide. The addition of aluminum, titanium, zirconium, niobium or uranium improved the SCC resistance of the nitrogen contaminated steel, possibly by decreasing the nitrogen content in solid solution, while vanadium, a weak nitride former, showed no effect. If carbide is precipitated, the SCC life is lowered since the carbon content in solid solution is decreased. It was indicated that aluminum, which forms nitride but does not react with carbon in solid solution, and uranium could be useful alloying elements in improving the SCC resistance of the air-melted stable austenitic stainless steel which might be contaminated with nitrogen.View full abstractDownload PDF (2246K) -
Hakaru Masumoto, Shôhachi Sawaya, Michio Kikuchi1972 Volume 36 Issue 2 Pages 176-181
Published: 1972
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMeasurements of Young’s modulus at −150°∼400°C and of rigidity modulus and hardness at room temperature have been carried out with Mn-Cu-Co alloys subjected to a variety of heat treatment and cold working. The Young’s modulus vs temperature curves of Mn-Cu-Co alloys containing about 10.15∼30.39%Cu and 4.62∼20.08%Co which were slow-cooled after heating for 1 hr at 900°C show distinct anomalous changes due to the antiferromagnetic\ ightleftarrowsparamagnetic transformation. The difference in the values of Young’s modulus at room temperature in the annealed, cold worked or water quenched state is hardly observable in the composition range of comparatively small manganese or cobalt content, but the difference becomes larger as the contents of these elements increase. The temperature coefficient of Young’s modulus is remarkably affected by annealing, water quenching, cold working, and reheating after water quenching or cold working, and also by alloy composition. And, the temperature coefficients of Young’s modulus as a function of composition exhibit large maximum and minimum values in positive or negative sign, thus showing the Elinvar-proporty. The variations in rigidity modulus and its temperature coefficient with temperature, reduction and composition show a close resemblance to those in Young’s modulus and its temperature coefficient. The values of hardness in the annealed, cold worked and water quenched states are generally lower than those in the reheating state after cold working or water quenching. And the oxidation and corrosion resistance of Mn-Cu-Co alloys are fairly satisfactory.View full abstractDownload PDF (2119K)
- |<
- <
- 1
- >
- >|