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Volume 31, Issue 7
Displaying 1-18 of 18 articles from this issue
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Kazutomo Oyama, Yoshihiko Suzuki, Osamu Izumi1967 Volume 31 Issue 7 Pages 821-826
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn experimental work of the high speed forward extrusion (ram speed ∼20 m/sec) using the “Dynapak” machine was carried out on Cu and Cu-10∼40%Zn alloys, and the results were analysed in relation to material composition, working temperature and extrusion speed.
The difference in composition yields variations in extrusion behaviors, such as the change in punch stress or velocity during extrusion, the relation between maximum punch stress and extrusion ratio, the temperature dependence of flow stress and the pattern of metal flow. Also, the high speed extrusion shows some different behaviors from those in the case of the slow speed one. For instance, in the former case, a linear relationship is established between maximum punch stress and working temperature, and the punch stress at each temperature successively increases with increasing Zn content (within α-phase). On the other hand, in the latter case, the punch stress changes exponentially against temperature, and its continuous change against Zn content can be seen only over a comparatively low temperature range.View full abstractDownload PDF (999K) -
Kazutomo Oyama, Chosei Ueda, Osamu Izumi1967 Volume 31 Issue 7 Pages 826-833
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStructures were investigated on the specimens of copper and copper-10∼40 wt% zinc alloys exttruded at various temperatures up to near solidus using the “Dynapak” machine.
Compared with the case of slow speed hot-extrusion, in which the working strain is simultaneously relaxed by recrystallization during deformation, the process of high speed hot-extrusion seemed rather similar to that in the case of cold-working. The material became to flow more uniformly with decreasing zinc content and with rising working temperature. The non-uniformly distributed “Shear markings” were observed in the extruded rods of the alloy specimen, and were sometimes developed to crack formation. In the region of the residual billet of the alloy specimen, the band-like “Strain markings” were observed. The markings developed differently with zinc content and working temperature: that is, they developed more remarkably in the specimen of higher zinc content and became widely spaced twin-like bands after deformation at elevated temperatures. An abnormal twin-structure, thought to relate to the formation of stacking-fault, was observed in the 70:30 brass billet deformed at 850°C. The extrusion at a high temperatures near solidus resulted in the failure of rods due to local melting by heat-generation. Two-phase alloy of 60:40 brass revealed a complex structure due to the phase change. Preferred orientations of the cold-extruded rods were also compared.View full abstractDownload PDF (2515K) -
Kunio Saijo, Sanji Nishimura, Yoshio Kondo1967 Volume 31 Issue 7 Pages 833-839
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDecarburizing high-carbon ferrochrome with chromium oxide (Eq. (\ efeq1)) at 1100° to 1400°C in vacuum was studied.
(This article is not displayable. Please see full text pdf.)
The results are summarized as follows:
(1) From thermodynamical investigations, the equilibrium partial pressure of carbon monoxide evolved were calculated as more than several mmHg. It is expected from this investigation that the vacuum below 10−1 mmHg is enough to complete the decarburizing reaction.
(2) The reaction starts at 850° to 950°C. Above these temperatures, the decarburizing rate increases with reaction temperature. In the case of an excessive rapid heating, however, the decarburizing is hindered by an eutectic melt formed at 1260°C. Chromium evaporates above 1200°C.
(3) Decarburization is found to be maximal in the stoichiometric mixture of ferrochrome and chromium oxide according to Eq. (\ efeq1). The briquetting pressure of 500 kg/cm2 gives the maximal decarburization.
(4) Among various oxides other than chromium oxide, V2O5 and Co2O3 show a good result. Their standard free energies of formation are rather small.
(5) An addition of catalyzer such as alkaline or alkaline earth fluorides improves the initial reaction rate. CaF2 was found to be the best catalyzer among them.
(6) Low carbon ferrochrome below 0.02%C can be prepared with stoichiometric mixture of high carbon ferrochrome and chromium oxide under the conditions of: [(a)] Decarburization at 1200°C for 10 hours. 1% of CaF2 is added as catalyzer, or [(b)] Two step decarburization at 1200°C in which 5 hours decarburization is repeated twice. The product is ground, mixed and briquetted between decarburizations.View full abstractDownload PDF (498K) -
Tadayuki Nakayama, Tatsuya Koizumi1967 Volume 31 Issue 7 Pages 839-845
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe breakaway phenomena of Zr and some Zr alloys during high temperature oxidation were studied from a structural point of view, by means of high temperature X-ray diffraction, thermal gravimetry, optical microscopy, and differential thermal analysis. The structural change in oxide scale at breakaway is in close relation with the polymorphic transformation of zirconium dioxide (tetragonal↔monoclinic). The continuous observation of change in oxide scales with high temperature X-ray diffraction clarified that black colored pre-breakaway oxide layers contained a considerable quantity of metastable tetragonal oxide, and that the color change of oxide layers from black to white and the polymorphic transformation to monoclinic oxide occurred simultaniously at breakaway. The contents of tetragonal modification in pre-breakaway oxide scales on Zr alloys containing Ti or Sn were larger than that on pure Zr, and this agrees reasonably with the facts that the breakaway occurs at lower temperatures on those alloys, and that those elements lower the transformation temperature of zirconium dioxide. In the stable region of the tetragonal form, the breakaway did not occur in O2.View full abstractDownload PDF (1855K) -
Natsuo Yukawa, Masayoshi Mizutani, Hiroyasu Saka1967 Volume 31 Issue 7 Pages 846-850
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the nature of age-hardening of 17-7 PH steel, the constitution of alloys containing 16∼19%Cr, 7%Ni, 0∼10%Al and the remainder Fe was investigated physico-metallurgically, through which the sectional diagram of the (17Cr-7Ni-Fe)-Al system was determined.
In this system, there exist δ(α) (bcc), α′ (ordered bcc of CsCl type based on NiAl) and γ (fcc) phases, of which the γ phase last transforms to martensite (αM) by quenching from 1050°C. On aging between 400°C and 600°C, α′ precipitates from both αM and δ matrices.
In commercial 17-7 PH steel containing about 0.07%C, M23C6 is formed in addition to the above-mentioned phases. In this case, however, γ is so stable that it is retained to room temperature during cooling from 1050°C. On annealing this metastable γ at about 800°C, it transforms to αM by subsequent cooling owing to the precipitation of M23C6. On further aging between 400°C and 600°C, α′ as well as M23C6 precipitates from αM and δ matrices, but the amount of the latter is negligibly small.View full abstractDownload PDF (1477K) -
Natsuo Yukawa, Masayoshi Mizutani, Hiroyasu Saka1967 Volume 31 Issue 7 Pages 850-854
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the previous paper, the phase changes in 17-7 PH steel were determined. In the present paper, the effect of Al upon its age-hardening characteristics was studied, and its nature was clarified.
The age-hardening of alloys free from δ(0∼1.2%Al) is enhanced markedly with Al content owing to an increase of α′ precipitates. In alloys with δ alone (>4%Al), however, α′ precipitates so rapidly that it cannot be suppressed even by water-quenching after solution treatment, and hence no appreciable age-hardening is observed on subsequent aging. Thus, the maximum hardening is obtained in alloys which consist of αM and a small amount of δ with about 1.5%Al corresponding to the Al content of the standard 17-7 PH steel. In commercial 17-7 PH steel with about 0.07%C, M23C6 carbide also precipitates from the matrix during aging, which, however, seems unlikely to be responsible for the age-hardening of this steel, because its amount is negligibly small.
Considering the results of the present and previous experiments, the remarkable age-hardening of 17-7 PH steel was attributed to the precipitation of α′ from αM.View full abstractDownload PDF (703K) -
Natsuo Yukawa, Masayoshi Mizutani, Hiroyasu Saka1967 Volume 31 Issue 7 Pages 855-859
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the previous papers, it has been reported that the age-hardening of 17-7 PH steel is attributable to the precipitation of α′ of the CsCl type. In the present paper, the morphology of α′ precipitation in the specimens used in the previous papers was studied by means of transmission electron microscopy, for purpose of confirming the age-hardening mechanism mentioned above. The technique of extraction replica was also applied to the problem.
The results obtained were as follows: (1) On aging at 400°C to 600°C after martensite formation, spherical α′ precipitates from αM as well as from δ with complete coherency with the parent matrix. (2) At the αM-δ interfaces, there also takes place a discontinuous precipitation of feather-like α′, which appears to grow into δ grains from interfaces. (3) The spherical α′ in the grains grows with aging time, and the peak hardness is obtained within an aging stage in which the diameter of α′ particles is less than 100 Å, regardless of the aging temperature ordinarily used. (4) On aging at about 600°C and above, a reverse transformation of austenite from martensite occurs, which results in rapid softening of materials concurrently with coagulation of α′.View full abstractDownload PDF (785K) -
Shozo Yoshioka, Yutaka Nakayama, Norio Hosokawa1967 Volume 31 Issue 7 Pages 860-865
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe yield stress of Al-7.0 at%Zn single crystals containing G.P. zones were measured at 77°K, 195°K and 293°K as a function of the quenching temperature of quenched specimens aged at room temperature for 20 hr and of the aging time of air-cooled specimens aged at room temperature. At the same time, the size and shape of G.P. zones were investigated by means of the measurement of X-ray small angle scattering and transmission electron microscopy. And then the relation between the yield stress and size of G.P. zones were deduced. The yield stress of quenched specimens varied with quenching temperature, i.e., the yield stress showed a maximum at a definite radius of G.P. zone, amounting to 32 Å. X-ray small angle scattering and transmission electron microscopic invertigations showed a change in the shape of G.P. zones at this size from spheres to ellipsoids. The temperature dependence of yield stress was also the largest for the specimen containing spherical G.P. zones. On the basis of these results, the observed yield stress variation of this alloy has been discussed.View full abstractDownload PDF (1891K) -
Hiroshi Mimura, Kôichi Aoki1967 Volume 31 Issue 7 Pages 865-868
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe strain rate sensitivity of flow stress in iron was studied when the concentration of solute carbon atoms was varied widely, and the following results were obtained.
(1) The strain rate sensitivity of flow stress is governed mainly by the concentration of solute carbon atoms at room temperature.
(2) Hardening due to solute carbon atoms is remarkable in the range of slow strain rates. The flow stress increases with solute carbon content at a rate of 5∼6 kg/mm2/[0.01%C].
(3) The influence of solute carbon atoms on the flow stress decreases when the temperature is low and/or the strain rate is high.
(4) The above feature can be explained in terms of the model which takes into account the Snoek effect due to carbon atoms.View full abstractDownload PDF (963K) -
Ohiko Kammori, Naoharu Yamaguchi, Hideo Kanno1967 Volume 31 Issue 7 Pages 869-874
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe detection limits and the precision of vacuum fusion-mass spectrometric analysis of microamounts of gases in iron and steel are considerably affected by both the blank value of crucibles and thermal insulators and the variation of the blank. Therefore, some kind of crucibles and insulators were compared to reduce the blank value.
The insulating method in which the crucible was wrapped by graphite fiber felt and graphite fiber powder was packed between them showed a lower blank value and made it easy to exchange the crucible and to evacuate the furnace.
The blank value of the graphite crucible was reduced by heating the crucible to red and washing in the boiling solution of sulfuric acid or by making many holes in the crucible, but the blank value obtained varied by each treatment. The glassy carbon crucible was found to be suitable only for small amounts of sample. The porous graphite crucible was best suited to the analysis of microamounts of gases in iron and steel: The blank value of oxygen in this crucible was approximately 1.0 μg/5 min, and it was proved that 0.5 g of oxygen could be determined by measuring the blank value before each analysis.View full abstractDownload PDF (1561K) -
Shoji Goto, Shigeyasu Koda1967 Volume 31 Issue 7 Pages 875-880
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBinary nickel alloys containing Cr up to 4 wt% as a solute element have been internally oxidized at temperatures between 900° and 1300°C to produce dispersed small Cr2O3 particles. The size and distribution of the dispersed particles and Vickers hardness of the internally oxidized layer have been determined. The results obtained are as follows. (1) The relationship between the depth of internally oxidized layer and the oxidation time of specimens followed a parabolic law. However, with increasing solute content and decreasing temperature, the internal oxidation due to grain boundary diffusion proceeded. (2) The size of dispersed particles in the internally oxidized layer became larger with the distance from the surface of the specimens. (3) The dispersed particles were rod-shaped crystalline Cr2O3, and in higher Cr content alloys, large lump shaped. (4) At a higher temperature of internal oxidation the size of dispersed particles became larger. With decreasing temperature and increasing solute content, the density of the dispersed particles was higher, and the Vickers hardness of the internally oxidized layer increased.View full abstractDownload PDF (2708K) -
Kyoji Nakanishi, Tunezo Saito, Yutaka Shiraishi1967 Volume 31 Issue 7 Pages 881-887
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSViscosities of molten iron and its dilute binary alloys of aluminum, silicon, and oxygen have been measured by the oscillating crucible method, as a part of the study concerning the physical properties of molten iron and its alloys.
The results are summarized as follows:
(1) Viscosity of pure iron between 1820°K and 1970°K is expressed as η(m poise) = 2.76 exp(10.8 ×10^3/RT).
(2) The addition of aluminum causes the decrease of viscosity which is larger than in the case of silicon. When the concentration of solute is 1 atomic%, the decrease of viscosity is about 36% by the addition of aluminum and about 15% by the addition of silicon.
(3) The addition of oxygen causes the increase of viscosity. The increase of the viscosity is 0.4 m poise/100 ppm O.
(4) Viscosity of molten aluminum containing dispersed alumina has been measured, and it has been shown that the increase of viscosity, compared with molten aluminum, is less than 1% when the volume fraction of dispersed alumina (∼10 μ) is 0.3%.
From these results, some considerations were given to the change of fluidity of steel in the deoxidation process. Thus, it has been concluded that the fluidity of steel does not change remarkably in the deoxidation process, provided that the products of deoxidation are uniformly dispersed.View full abstractDownload PDF (2045K) -
Toshisada Mori, Eiji Ichise, Yasuo Niwa, Masaaki Kuga1967 Volume 31 Issue 7 Pages 887-892
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of carbon and hydrogen on the solubility of nitrogen in austenite have been measured by the use of the quenching method. To determine the effect of hydrogen, the pure iron specimens were equilibrated with N2+H2 gas mixtures, and the effect of hydrogen partial pressure on the solubility of nitrogen was investigated instead of determining the dissolved hydrogen contents because of the difficulty for analysing the dissolved hydrogen. The determination of the effect of carbon was performed under the atmosphere having a constant carbon potential in order to prevent the decarburization of specimens. The constant carbon potential atmosphere was prepared by adding CO+CO2 gas mixtures, having a fixed gas ratio, to the N2 gas flow. The results obtained are as follows:
(1) Hydrogen accelerates the denitrogenization when the cooling rate of the nitrogenized specimen is small, but
(2) Hydrogen has no effect on the activity coefficient of nitrogen in austenite, i.e., e_N^(H) = 0 (1050° ∼1250°C).
(3) The effect of carbon on the activity coefficient of nitrogen in austenite is expressed as e_N^(C) = 395/T-0.183 (1050° ∼1250°C).
(4) The value of interaction parameter of carbon in austenite is smaller than that in liquid iron, which may be explained by the fact that upon fusion of iron, there is a drastic increase of lattice imperfections, i.e., holes which are capable of accomodating interstitial atoms.View full abstractDownload PDF (1493K) -
On the Determination of Microamounts of Bismuth in High Alloy Steel by the Spectrophotometric MethodTakashi Sakaki1967 Volume 31 Issue 7 Pages 893-898
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn experiment was carried out to establish a simple and accurate method for the determination of microamounts of bismuth in high alloy steel.
The bismuth was separated as a thionalide complex from iron and other elements in an ammoniacal solution in which were masked these elements by the use of ammonium tartarate, sodium cyanide and sodium sulfite. By means of the separation method with thionalide, the microamounts of bismuth can be separated easily and accuratlly from large amounts of various elements. Niobium and tantalum were coprecipitated as pentaoxides with tungstic acid by the hydrolysis method with sodium sulfite in a perchloric acid medium to which was added 5 mL of sodium tungstate solution (1 mL=1 mg W) as coprecipitating reagent and were separated beforehand from other elements.
The separated bismuth was determined by the spectrophotometric method with dithizone.
In this dithizone method, the formation and extraction of the bismuth dithizonate complex were done in a perchloric acid medium containing ascorbic acid, and in this way the most suitable pH is found to be 2.0±0.2.
This dithizonate complex is extracted with benzene quantitatively and readily.
The absorption maximum of this dithizonate complex is at 510 mill microns when the absorption is measured against a dithizone benzene solution reference. At this wavelength, the relation between the amounts of bismuth and the absorption follows Beer’s law in the range from 0 to 25γ/10 mL of bismuth.
As a result of the experiment, the author succeeded to establish a method in which less than 0.005% of bismuth in high alloy steel can precisely be measured without difficulty.
The bismuth contents in synthetic samples were measured by this method with satisfactory results.View full abstractDownload PDF (1893K) -
Yunoshin Imai, Masao Izumiyama, Shuji Hanada1967 Volume 31 Issue 7 Pages 898-903
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to evaluate the effect of the cyclic heat treatment on the martensitic transformation, the investigations on dilatation curves, on microstructures and on mechanical properties were carried out using the iron-nickel binary alloys containing 24.50 to 30.70 atomic per cent nickel. The Ms temperature lowered with the increase in the numbers of cyclic heat treatment so that the amount of martensitic transformation also decreased. The optical and electron microstructures of martensite after the cyclic heat treatment consisted of finer martensite platelets and of high dislocation density. The hardness and tensile strength of austenite were remarkably increased by the cyclic heat treatment at the early stage, but in the case of the martensite they were not remarkably increased. The driving force necessary for initiating martensitic transformation increased with the increase in the numbers of cyclic heat treatment. It was suggested that these results will be caused by a mechanism based on the concept of the work hardening of austenite due to the cyclic heat treatment.View full abstractDownload PDF (2059K) -
Toshio Katagiri, Kyoko Fujii, Nobujiro Takamoto1967 Volume 31 Issue 7 Pages 904-909
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo study the effect of Ni and Cr on the formation of borider layer the gas boronizing of Fe-Ni alloy, Fe-Cr alloy and Ni with BCl3 and H2 were carried out in the temperature range from 700°C to 1000°C. From microscopic examination, X-ray diffraction, the measurement of microhardness and chemical analysis, the following results were obtained.
(1) The boride layer comprised of two layers of (Fe, Ni)B and (Fe, Ni)2B in Fe-Ni alloy, and FeB and Fe2B in Fe-Cr alloy.
(2) The boride layer of Ni was made up of three layers, in which NiB and Ni2B were observed.
(3) 40% or more addition of Ni accelerates the formation of the boride layer of Fe-Ni alloy, but its formation is impeded in Fe-Cr alloys as the addition of Cr is larger.
(4) Microhardness of the boride layers of Ni and permalloy is smaller than that of iron.
(5) The boride layers had a high corrosion resistance against corrosive action of 10%- and concentrated aqueous solution of HCl and H2SO4 but were badly damaged by 10%- and concentrated HNO3.View full abstractDownload PDF (2258K) -
Yoshio Baba1967 Volume 31 Issue 7 Pages 910-915
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInfluences of additions of Li, Be, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ge, Zr, Mo, Ag, Cd, In, Sn, Sb, Pb and Bi less than 0.5 at% on the quench-sensitivity, or the loss of strength on slow quenching, of Al-2.5 at%Zn-2 at%Mg alloys were studied from the measurements of hardness and electrical resistivity and also electron microscope observations, and proposed models on the nucleation of precipitates to explain the mechanism are discussed with particular attention to the role of lattice defects. The results are as follows:
(1) The quench-sensitivity of Al-Zn-Mg alloy is most markedly increased by the addition of Cr, followed by that of Mo, V, Zr, Mn (group a), Cd, Ag, Be, Cu (group b) and the others, in the order named. Microstructural evidence and change in electrical resistivity indicate that the effects of quench-sensitivity are attributable to the precipitation, during slow quenching, of solute in an incoherent form in which it could make no contribution to subsequent age-hardening.
(2) The effect of group (a) can be reasonably explained in terms of the increase in crystal defects such as dislocations, sub-boundaries, grain boundaries and especially misfit surfaces around microscopic insoluble compounds formed by these additional elements which act as preferential nucleating sites for the precipitates M(MgZn2). On the other hand, the atoms of group (b) in supersaturated solution may form clusters which act as the heterogeneous nucleation center for the precipitates, although a large quantity of Cu in solution may also have the effect of reducing the solubility of Zn and Mg.View full abstractDownload PDF (2545K) -
Masanobu Ohmori, Yoshitoyo Yoshinaga1967 Volume 31 Issue 7 Pages 916-921
Published: 1967
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUsing a parallel-straight-edged shearing tool, the behaviors in shearing of the annealed sheet, 0.6 mm in thickness, made from a killed carbon steel with 0.14%C were investigated, as a function of the shear rate, in a wide range of rates from 1.1×10−2 to 2.8×104 l/sec. The present main findings are summarized as follows:
(1) The present shearing resistance has two strain rate sensitivities, i.e., a larger sensitivity beyond the rate of 1 l/sec and a much smaller one below the rate of it as the deformation resistances under the other states of stress such as simple tension, compression and torsion have two sensitivities, respectively. The shearing resistance, though it is somewhat smaller than the maximum shearing stress observed under simple torsion of the thin walled cylinder, increases with the shear rate in quite parallel with the maximum shearing stress.
(2) Defining the tensile and shear strain rate which should give an equal octahedral shear rate as an equivalent strain rate, the ratio of the shearing resistance to the tensile strength in a higher speed deformation was found to be appreciably smaller than the ratio 0.78 obtained in a quasi-static deformation.
(3) When the sheet was sheared in an impact manner with the present highest rate of 2.8 m/sec, the sheared edge showed the change characterized by the slight decrease of shear droop. However, no change was found in the edge at lower rates than 2.8 m/sec.View full abstractDownload PDF (1799K)
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