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Volume 40, Issue 12
Displaying 1-17 of 17 articles from this issue
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Mutsuo Ohta, Teruto Kanadani, Hironobu Maeda1976 Volume 40 Issue 12 Pages 1199-1205
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSeveral Al-Zn alloys containing 0.041∼4.4 at%Zn were studied by means of measurements of electrical resistivity. The results obtained are as follows: (1) The electrical resistivity increases when the specimen is annealed at temperatures higher than the soluvus temperature of the G.P.zones. This increase of resistivity is due to the formation of clusters. (2) The electrical resistivity of the specimen containing clusters is dependent upon annealing temperature only and independent of quenching temperature. (3) Clusters are formed in very dilute alloys as 0.041 at%Zn at temperatures higher than the solvus temperature of the G.P.zones. (4) The formation energy of vacancy and the migration energy of the Zn atom in the alloys determind by the formation process of clusters are in good agreement with those by the formation process of G.P.zones. (5) In spite of the result (4), it seems that the clusters are not the same ones as the small G.P.zones which are observed in the early stage of aging.View full abstractDownload PDF (580K) -
Kazuyoshi Sekine, Osamu Yoshimura1976 Volume 40 Issue 12 Pages 1205-1208
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe generalized maximum work procedure proposed by the authors (J. Japan Inst. Metals, 40 (1976), 457), in which the rotation vector of crystals under constrained deformation can be determined uniquely, was applied to the calculation of lattice rotations in bcc metals deforming by {110}⟨111⟩ and {112}⟨111⟩ slip systems for axisymmetric tension and compression. The computer-predicted results indicated that the ⟨110⟩ single fiber texture in tension and the ⟨111⟩+⟨100⟩ double fiber texture in compression develop in bcc metals.View full abstractDownload PDF (316K) -
Shuichi Komatsu, Masako Nakahashi, Itaru Watanabe, Kazumi Shimotori1976 Volume 40 Issue 12 Pages 1208-1215
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt had been found that 40Cr-4Al-Ni alloy showed extremely high age-hardenability. The hardness of this alloy, for example, was approximately 680 Hv after heat treatment at 700°C for 30 min. The age-hardenability was suggested to be derived from the duplex precipitation of Ni3Al type γ′ and α-Cr phases. However, the morphology of the precipitated phases has not been clarified.
In the present work, the transmission electron microscopic observation was made on the specimens heat treated at various temperatures. It was found that γ′ and α phases showed different morphologies in three temperature regions, below 500°C, 550∼700°C and 800∼900°C. In the region below 500°C only the α phase precipitated. The maximum age-hardenability was attained in the temperature region of 550∼700°C. In this region fine γ′ particles precipitated in the matrix and then cellular precipitation started rapidly at the grain boundary. In the cellular precipitation region the α phase was observed in the shape of fine lamellar structure. The lamellar γ′ phase precipitated at the interface between the α phase and the γ-matrix.
The characteristic formation of these three layers composed of α, γ′ and γ-matrix phases seemed to correspond to the maximum hardness observed in this alloy. In the 800∼900°C region fine γ′ particles were not detected in the matrix and the α phase changed to granular morphology in the cellular precipitation region. The precipitation behavior of the α, γ′ duplex phases and its effect on the age-hardenability are discussed.View full abstractDownload PDF (1125K) -
Hiroyuki Yoshida1976 Volume 40 Issue 12 Pages 1216-1223
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy means of electron microscope observations based on the weak-beam method as well as the conventional technique, the size distributions of G.P. zones in Al-3.97%Cu alloy were measured for various stages of low temperature aging. The results obtained are summarized as follows:
(1) Weak-beam electron microscopy shows clearer images of G.P. zones and the size much closer to real size for small zones than the conventional technique. Individual G.P. zones could be identified and the diameters of G.P.(I) zones, 2-layer G.P.(II) zones and multi-layer G.P.(II) zones were measured by defining their structures.
(2) All of the size distributions measured represent the normal distribution function, except for very small G.P.(I) zones close to the minimum size of the zone structure. In case the G.P.(I)zone, 2-layer G.P.(II) zones and multilayer G.P.(II) zones coexist, each of these zone structures represents the normal distribution. The results suggest that the nucleation and growth of G.P.(I) zones as well as G.P.(II) zones occur by a random process.View full abstractDownload PDF (1085K) -
Yutaka Hiraoka, Kozo Osamura, Yotaro Murakami1976 Volume 40 Issue 12 Pages 1223-1228
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is well known that during a preprecipitation process in which the formation of Guinier-Preston zones takes place, an increase of resistivity at its early stage, followed by a decrease, occurs in a number of age-hardenable aluminium-base alloys. Recently we have experimentally determined the contribution of one G.P. zone to the electrical resistivity and discussed the influence of size and shape of G.P. zones on the scattering power in Al-Zn alloys. It has been shown that the scattering power of a G.P. zone increases with its size.
The objects of the present paper are to investigate in detail the influence of size and inner structure of G.P. zone on the scattering power for Al-Ag alloys in which two kinds of G.P. zones are known to form at each aging temperature and to compare with the scattering power of G.P. zones in Al-Zn alloys. The electrical resistivity and X-ray small-angle scattering measurements have been performed for several Al-Ag alloys aged at 140 and 190°C.
It is shown that the scattering power of a G.P. zone increases with its size, though the size dependence is different for each aging temperature. This behavior of the scattering power is explained in terms of the difference in the inner structure of G.P. zones in Al-Ag alloys.View full abstractDownload PDF (500K) -
Kozo Osamura, Shigeki Furuichi, Kan Kanbayashi, Seizo Takamuku, Yotaro ...1976 Volume 40 Issue 12 Pages 1228-1237
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSX-ray diffuse scattering intensity around the 110 reciprocal lattice point was measured in order to obtain the volume fraction and the mean diameter of precipitates. The discrimination of the precipitated phases was performed by the aid of X-ray Laue analysis and the electron diffraction patterns. The electrical resistivity was carefully measured.
When the alloy was aged for 1000 min at 100°C, G.P.zones precipitated with a mean diameter of 80 Å. During the reversion, these zones dissolved perfectly above 185°C, which is in good agreement with the result of Beton and Rollason. After the perfect dissolution of G.P.zones, the θ′ phase precipitated solely and heterogeneously, perhaps at dislocation loops.
By aging for 4000 min at 135°C, the θ″ phase precipitated with a mean diameter of 125 Å. When this alloy was reverted, the temperature at which the volume fraction of precipitates becomes minimum but not zero was 225°C, where the successively precipitated θ′ phase exsisted.View full abstractDownload PDF (1231K) -
Yoichi Ishida, Ken Inoue, Koichi Sassa, Masao Kato1976 Volume 40 Issue 12 Pages 1238-1242
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe influence of grain boundary structure on the boundary diffusion of 65Zn at 100 and 150°C in coarse grained pure aluminium was analysed by the electron channeling pattern and Auger electron autoradiography. Precise determination of the orientation relationship is achieved by the former, while the boundary segregation of zinc of the order of 0.01% is analysed by the latter technique. Diffusion enhancement was observed in most of the grain boundaries to a varying degree: In 40% of the boundary triple point the enhancement in one boundary was less than half of the other boundaries. One-third of such boundaries were small angle boundaries and the rest were mostly coincidence boundaries.View full abstractDownload PDF (578K) -
Hidehiko Kamide, Hideo Sugawara1976 Volume 40 Issue 12 Pages 1243-1249
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe stress corrosion cracking (S.C.C.) behavior of 18-8 stainless steel in a 5 N H2SO4-0.4 M NaCl solution at −325 mV (vs S.C.E.) was investigated to examine whether the strain-induced martensite would may give rise to S.C.C.
As prestraining, the elongation of 27% in tension was made at various temperatures between 20 and 160°C. X-ray diffraction and transmission electron microscopic observations showed that the specimen prestrained at 40°C contained α′ and ε-martensitic phases in the austenitic matrix. The S.C.C. susceptibility of the specimens varied with the annealing temperature ranging from 20°C to 1100°C for 120 min. S.C.C. was observed for specimens treated at temperatures below 600°C where α′-martensite persisted. The number of cracks on the specimen after the S.C.C. test decreased with increasing temperature of prestraining and S.C.C. was not observed at temperatures above 140°C. α′ and ε-martensitic phases were not detected by electron diffraction analysis in the specimens prestrained above this temperature.
The corrosion striation on the specimens surface, which was prestrained at a temperature below 120°C, developed during immersion in a 5 N H2SO4-0.4 M NaCl solution at −325 mV for 120 min. The same striation was found near the crack tips, when the cross section of the specimen after the S.C.C. test was polished and immersed in the solution.
It is concluded that the occurrence of martensite structure in 18-8 stainless steel may enhance the S.C.C. susceptibility in H2SO4-NaCl solutions.View full abstractDownload PDF (1632K) -
Hiroshi Imagawa, Kouji Nakamura1976 Volume 40 Issue 12 Pages 1250-1256
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relation between the corrosion cracking of ammonia spherical storage tanks and the quality of liquid ammonia, which changed with the manufacturing processes, was studied by means of the analysis of impurities in the liquid ammonia and corrosion cracking tests for WOL type specimens 80 kg/mm2 high strength steel. The results obtained are as follows:
(1) Branched corrosion cracks were observed within one year on the base metal near its welding line and on the base metal near its welding line in the liquid zone of the tank when it stored the liquid ammonia at atomospheric temperature.
(2) Corrosion cracking of ammonia storage tanks has become more serious after the improvement of the manufacturing process of ammonia. The liquid ammonia of the old plant contained almost the same amount of CO3−−, but about ten times as much oil as that of the new plant.
(3) The liquid ammonia contained water, oil, carbonate and chloride as impurities. After evaporation they were concentrated in the residue, in which CO3−− and Cl− were contained about 22000 ppm and 10∼220 ppm respectively.
(4) Corrosion cracking of quenched specimens occurred in liquid NH3+5 wt%NH4CO2NH2 or liquid NH3+5 wt%NH4HCO3 within a week at 30°C. On the other hand, the number of cracks was reduced by adding air, oil or NH4Cl to the former environment.
(5) The carbonate is believed to be the most important contaminant for the corrosion cracking of the steel in the liquid ammonia.View full abstractDownload PDF (820K) -
Hiroshi Imagawa1976 Volume 40 Issue 12 Pages 1256-1263
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAnodic polarization and corrosion cracking behavior of 80 kg/mm2 high strength steel (HT 80) were investigated in liquid ammonia containing ammonium carbonate (saturated-accelerated corrosion cracking environment) or ammonium chloride at 30°C. The results obtained are as follows:
(1) Corrosion potential vs Pt electrode (Ec) for HT 80 was −0.10 V in liquid ammonia and −0.7 V in the accelerated environment, respectively. In the latter environment, HT 80 showed an unstable active-passive behavior, and corrosion cracking occurred in quenched HT 80 when it was in contact with 304 stainless steel. Under this cracking condition Ec for HT 80 was easily shifted to a noble potential in the active-passive transition region.
(2) In the accelerated environment, the passivation current density for HT 80 decreased with an increase of air content in the nitrogen gas used for purging the test vessel before filling it with liquid ammonia. But no corrosion cracking occurred in quenched HT 80 under this condition.
(3) Although cracking occurred when 0.20 mA/cm2 cathodic current was applied to the HT 80 specimen, general corrosion was only accelerated when anodic current was applied to it at a constant strain in the accelerated environment.
(4) HT 80 showed an unstable active-passive behavior in the accelerated environment when the test vessel was purged by argon instead of nitrogen, and corrosion cracking occurred in quenched HT 80 when it was in contact with 304 stainless steel under this condition.
(5) In the liquid ammonia containing chloride, an unstable active-passive behavior was shown in HT 80, but no corrosion cracking occurred in HT 80 even if it was in contact with 304 stainless steel. Ec for HT 80 was slightly shifted to a noble potential under this condition.View full abstractDownload PDF (645K) -
Norihiko Fukatsu, Satoru Usuki, Zensaku Kozuka1976 Volume 40 Issue 12 Pages 1263-1270
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to control oxygen potential in gas atomosphere automatically, an apparatus was constructed utilizing an oxygen pump and oxygen sensor consist of stabilized zirconia with the porous platinum electrodes, and the performance of this apparatus was investigated.
For the oxygen potential, the buffer capacity of Ar-O2 and CO-CO2 gas mixtures was evaluated and plotted as a function of oxygen partial pressure at 800°C. Because the CO-CO2 gas mixture was found to have a good buffer capacity over a wide range of oxygen potential, it was employed in the present experiment.
The purified CO2, as a starting material, was filled and circulated in a closed system. Circulating gas was electrolyzed by the oxygen pump and CO2 was dissociated until the oxygen sensor showed the desired oxygen potential. A feedback control unit was used between the oxygen pump and the oxygen sensor.
The oxygen potential of the circulating gas was measured as a function of temperature by an oxygen sensor at another position and it was found that the composition of circulating gas was kept constant by this control system. The control of the oxygen potential corresponding to the PO2 range 2.8×10−3∼1.5×10−20 atm was tested at 800°C using this apparatus. In the whole range, except PO2=1.15×10−6∼2.69×10−9 atm, the oxygen potential was controlled in a very stable manner. The range of the unstable oxygen partial pressure was in accord with that of minimum buffer capacity.
The oxygen potential dependence of electrical resistance of a TiO2 specimen was measured employing this apparatus, and the result agreed with the other reliable data.View full abstractDownload PDF (683K) -
Influence of Nb(C, N) Precipitation in Austenite on the Mechanical Properties of High Strength SteelHiroshi Kobayashi1976 Volume 40 Issue 12 Pages 1270-1276
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffect of Nb content on the mechanical properties of high strength steel has been studied for hot strips rolled in the conventional (regular) or controlled process and also for the normalized one.
On the conventional rolling, Nb(C, N) precipitated in ferrite, but not in austenite. The yield strength of the steels increased with Nb content.
On the controlled rolling where Nb(C, N) was intended to precipitate in austenite on the basis of the kinetics, many particles of Nb(C, N) precipitated during rolling in austenite containing more than 0.10 wt%Nb. The yield strength did not change with Nb contents higher than 0.05 wt%.
Because of the low precipitation rate, Nb(C, N) did not precipitate in austenite of steels containing less than 0.05 wt%Nb by any rolling condition.
The toughness of the steels subjected to controlled rolling and normalization was improved with increasing Nb content, without any alternation of the yield strength. This has been attributed to the reduction of dissolved nitrogen, which has an extremely unfavorable effect on the toughness, as a result of the formation of noncoherent Nb(C, N) in austenite.
Based on the above results, a new type of high strength steel with superior tougness has been developed by somewhat higher Nb addition and by the specially controlled rolling in which Nb(C, N) was intended to precipitate in austenite.View full abstractDownload PDF (1203K) -
Nobuyuki Mori, Keisaku \={O}gi, Kimio Matsuda1976 Volume 40 Issue 12 Pages 1276-1283
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAs the segregation results from both the distribution of solute at the freezing front and the diffusion of it in solid during solidification, the pattern of the segregation should be determined by the processes of crystal growth. Especially in dendrite growth, it is natural that the coalescence and coarsening of dendrite arms should influence the microsegregation. In this paper, the mechanism of solute redistribution in dendrite growth was studied. Al-Cu alloys containing 5.5, 15 and 27% copper were quenched during solidification, and the distribution of copper in dendrites were quantitatively analyzed with Electron Probe Microanalyzer.
The effective distribution coefficient of copper to primary α-phase became larger with increase in cooling rate. This suggests that the larger cooling rate results in the higher solute concentration in the liquid near the dendrite tip.
Copper concentration in the core of dendrite increased with the fraction of solid, and that was greater at lower cooling rate.
The fair difference of concentration between the measured values and calculated ones from Flemings method(13) suggests that the dendrite grows mainly accompanying the coalescence.View full abstractDownload PDF (820K) -
Seita Sakui, Taku Sakai, Hiroharu Sawada1976 Volume 40 Issue 12 Pages 1284-1291
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh-temperature tensile deformation of alpha iron was studied in the temperature range 500 to 900°C over a wide range of strain rates from 18 to 3.1×10−6 l/sec. The steady-state flow stress or maximum flow stress, σM, can be correlated with temperature, T, and strain rate, \dotε, approximately by the following deformation equation; \dotε=A·σMm·exp\left(−\dfracQRT\ ight), in which m=4.9 and Q=74 kcal/mol above the Curie temperature, Tc, and m=5.2 and Q=85 kcal/mol below Tc. These values are nearly equal to those obtained in creep experiments. The apparent activation energy for deformation determined under the stress normalized by elastic modulus (σ⁄E) is 61.0 kcal/mol above Tc and 62.5 kcal/mol below Tc, being almost the same as those for self-diffusion in alpha iron.
Metallographic investigation was done on specimens quenched by hydrogen gas instantaneously after deformation. Stable equiaxial subgrains were formed before reaching the steady-state in the high stress range, whereas in the low stress range subgrain formation was finished during the steady-state. The mean subgrain size, d, is unchanged in the region of high strain and is expressed solely in terms of σM, independent of the initial grain size and T or \dotε. The relation between σM and d is approximated by the equation, σM=K⁄d (K is constant) in the stress range below σM\simeq5.4 kg/mm2. This relation is altered above 5.4 kg/mm2 and K becomes several times larger than that in the low stress range. These results indicate that the deformation in the stress range below 5.4 kg/mm2 is controlled mainly by the dynamic recovery process assisted by the migration of vacancies, and the deformation in the high stress or hot working range is controlled by the dynamic recovery process and during the deformation the dislocation glide is considered to play an important role.View full abstractDownload PDF (1316K) -
Kosaku Nakano, Yasunobu Kobayashi, Akihiko Kamio, Shigeo Oya1976 Volume 40 Issue 12 Pages 1291-1297
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe 99.99% pure copper and its alloys were unidirectionally solidified and decanted to examine the morphology of the solid-liquid interface. The interfacial morphology shows transitions from plane to depressions, irregular cells, elongated cells, hexagonal cells, broken cells and dendritic cells, successively, with the decrease of freezing conditions G⁄RC0 and are governed strongly by the distribution coefficient of solutes in alloys (where G is the temperature gradient in the liquid, R is the growth rate and C0 is the initial solute concentration). Each morphological transition occurs under constant G⁄RC0. These critical conditions in copper-base alloys are much smaller than those in other alloys, such as tin, lead and aluminum alloys.
The entrapping of solutes into the solid at the interface during freezing forms segregating regions. According to the degree of constitutional undercooling, these regions increase their areas in forming depressions, cell nodes or cell walls. The solute content at cell nodes in the hexagonal cell interface is about 8 times as much as C0 in Cu-Mn alloys, about 12 times C0 in Cu-Ti alloys, about 7 times C0 in Cu-Sn alloys and about 30 times C0 in Cu-Cr alloys.View full abstractDownload PDF (1421K) -
Toshiya Wada, Katsuro Kuroki, Toshihiko Takata1976 Volume 40 Issue 12 Pages 1298-1303
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe cold rolled texture of 3%Si-Fe(001)[100] is composed mainly of (001)⟨hkl⟩ which is formed as a result of rotation of original (001)[100] about the rolling plane normal. However, many minor components of which (001) were not parallel to the rolling plane were reported to exist.
These minor components were investigated in this study using an (001)[110] single crystal and bi- and tri-crystals composed of (001)[110] and near (001)[110].
The main results were as follows:
Minor components of which (001) were not parallel to the rolling plane existed evenly throughout the specimen after 70% cold reduction where deformation bands and transition bands were clearly formed. With increased reduction, the amount of minor components increased, and their mean angle of (001) from the rolling plane were 18 degrees at 70%, and 25 degrees at 90%. The regions where degree of tilting of (001) was large corresponded to the point where either deformation band disappeared or transition band were fouled. The direction of rotation was adverse each other in both sides of a transition band, and the rotation axis was ⟨110⟩.
After cold rolling the (001)[110] bi- and tri-crystals to 80% reduction, a quite similar phenomenon to the single crystal mentioned above was observed; tilting of (001) from the rolling plane, 10∼20 degrees, was observed along the grain boundaries.
The rotation axis was ⟨110⟩ and the directions of rotation were adverse each other in both sides of the grain boundary.
From these facts it was concluded that minor components of which (001) were not parallel to the rolling plane in rolled (001)[100] single crystals were caused by a constraining effect of the transition bands during rolling as grain boundary does in polycrystals.View full abstractDownload PDF (1049K) -
Nobuyoshi Hara, Katsuhisa Sugimoto, Yoshinobu Sawada1976 Volume 40 Issue 12 Pages 1304-1310
Published: 1976
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSElectrical properties of the interface of 18-8 stainless steel electrode in the passive and transpassive states have been studied by using complex impedance diagrams measured in 1 M-Na2SO4 with pH 2.0 and 6.4.
The diagrams obtained in the passive region always showed distorted hemicircles which were equivalent to the impedance loci of electrical circuits having several parallel RC circuits connected in series. It is thought, therefore, that passive films are composed of several layers whose electrical properties are different from one another. Using the resistance at zero frequency (Rω→0) of the diagram and the film thickness which was obtained by ellipsometry, the apparent specific resistance of the passive film was estimated to be ca. 2×1012 Ω·cm.
In the transpassive region, the diagrams measured exhibited an inductive loop at extremely low frequencies in addition to a capacitative hemicircle which appeared at high frequencies. The appearance of an inductive loop means that the transpassive dissolution process contains a relaxation process with a large time constant.View full abstractDownload PDF (580K)
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