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Volume 32, Issue 3
Displaying 1-19 of 19 articles from this issue
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Jun-ichiro Yagi, Akira Moriyama, Iwao Muchi1968 Volume 32 Issue 3 Pages 209-213
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy means of the expression of the reaction rate, Eq. (3), which has been reported by the authors(4)(5), the fractional reduction of pellets in a moving bed is determined as the function of operating conditions.
On the assumptions that the temperature in the bed is constant and the distributions of both gaseous concentration and fractional reduction of pellets in the redial direction are uniform, Eqs. (4) and (5) are derived by the material balances. These equations are non-linear and impossible to solve analytically. However, they are linear in the extreme cases of the piston flow and the complete mixing of gas flow, for which Eqs. (12) and (19) are obtained as their solutions. The fractional reductions of pellets are shown in Figs. 2∼5 under various operating conditions. For the case of the incomplete mixing in which cannot be analytically solved, Eqs. (4) and (5) are numerically solved with the aid of a digital computer. The effects of the mixing of gas flow on the longitudinal distributions of the gaseous concentration and the fractional reduction of pellets are illustrated in Figs. 6 and 7. Fig. 8 represents the results when CO and H2 are used as the reducing gases. Conclusively, the effect of the longitudinal mixing of gas flow on the fractional reduction of pellets is not great and it has been found that at 1000°C the reduction rate by H2 gas is faster than that by CO.View full abstractDownload PDF (1239K) -
Toshiro Kobayashi, Koichi Takai, Hideyo Maniwa1968 Volume 32 Issue 3 Pages 213-217
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy sectioning Charpy specimens with various types of notches from Mn-Mo steel for reactor pressure vessels and recording the relationship between load and time during impact, the energy absorbed in the Charpy test was analyzed. The size effect of specimen width on the transition behaviour was also examined.
As a result of these, it was found that the transition in the present standard specimens was able to be divided into six temperature regions as reported in the previous paper. Furthermore, the temperature at the shoulder of the transition curve (\simeqTr100s) is considered to be important as a transition temperature because the energies divided have a tendency to reveal a peak value near this temperature range.
Although a linear relationship was observed between the ductility transition temperature and the size of specimen width in the standard specimen, the size effect on the propagation transition temperature was not observed clearly. Similarly, in the crack-propagation type specimens such as press notch, press-boundary notch and low-blow test specimens, the size effect was not observed. Such an effect rather appeared in the gradient from the shoulder of the transition curve in the standard specimens; and the temperature at the shoulder (\simeqTr100s) was not affected by the specimen size. Therefore, this temperature is considered to be important as a crack-propagation transition temperature when correlations with a large specimen test are studied.View full abstractDownload PDF (1789K) -
Seiichi Karashima, Tadashi Hasegawa, Minoru Yokota1968 Volume 32 Issue 3 Pages 218-224
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSubstructures in aluminium crept at high temperatures were investigated by means of the Berg-Barrett method and transmission electron microscopy.
In single crystals crept at 0.85Tm (Tm means the melting temperature in Kelvin), square-shaped subgrains with sub-boundaries parallel to deformation bands and slip lines were observed in the transient creep region. However, such sub-boundaries were so mobile that well-defined large (300∼a few thousand μ) subgrains of the polygonal shape were finally formed in steady-state creep. It was also observed that some subgrains broke up into smaller ones at some place of the specimen, while some other subgrains grew up at a different place simultaneously. This fact suggests that deformation and recovery processes occur locally at the same time.
On the other hand, in copper crept at the same homologous temperature and creep rate as in aluminium, square-shaped subgrains were observed even in the steady-state creep region as reported in a previous paper. In aluminium, however, these square-shaped subgrains were formed in the steady-state only at lower testing temperatures and at higher strain rates.
Such a difference in subgrain formation between aluminium and copper may be due to the difference in stacking fault energy.
In polycrystalline specimens, the subgrain size formed by creep deformation was generally smaller than that in single crystals. Also, it was frequently observed that the subgrain size and the direction of sub-boundaries were different from place to place in one grain.
In transmission electron microscopy, sub-boundaries parallel to low index planes, such as slip plane (111) and deformation band (110), were generally observed. Dislocation networks and dislocation images parallel to [112] were sometimes observed in (111) and (110) sub-boundaries, respectively. However, most of the sub-boundaries were generally composed of more than two sets of dislocations.View full abstractDownload PDF (3011K) -
Genjiro Mima, Toshimi Yamane, Chiaki Hayashi1968 Volume 32 Issue 3 Pages 224-227
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSome intermetallic compounds have excellent electric and magnetic characteristics, and their compositions, structures and dispersion phases in matrix have been investigated. Recently mechanical properties and fracture behaviors have drawn increasing attention. But litte has been reported on plastic working to manufacture plates and wires.
As the first step of investigation of mechanical working of intermetallic compounds, the plasticity of CuAl2 were investigated by high temperature compression tests, creep tests and electrical resistivity measurements.
Main experimental results obtained are as follows:
(1) At room temperature, CuAl2 is brittle. Cracks are formed at the edges of micro-Vickers hardness cone depression even by a load of 500 g.
(2) CuAl2 has a little plasticity at 475° and 500°C. At temperatures higher than 525°C, the plastic deformation capacity increases remarkably.
(3) There is a linear relation between logarithmus of 0.2% yield stress and absolute temperatures.
(4) Creep curve of CuAl2 has a tendency of metallic creep curves with the first, second and third stages.View full abstractDownload PDF (1186K) -
Genjiro Mima, Toshihiro Oka1968 Volume 32 Issue 3 Pages 228-233
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDuring the creep test in vacuum at high temperatures under constant tensile load, with their boundaries aligned at 45 deg. to the tensile axis of 99.99% aluminium bicrystal specimens, grain boundary sliding and shear deformation near the boundary were measured. The grain boundary sliding was accompanied by crystal shear deformation near the boundary, and the observed grain boundary displacement had no relation with the boundary misorientation angle ω, but with the angle α or β between the crystal slip plane trace and the boundary trace at the observed plane of the bicrystal specimen.
The sliding along the boundary with a large misorientation angle ω acted preferencially on the boundary itself (pure sliding), and the sliding along the small misorientation angle boundary was shear deformation of component crystals adjacent to the boundary (zone sliding). The over-all deformation (elongation) of the specimen was measured without observable crystal slip within component crystals. And migration of the common boundary proceeded in the direction to release the strain energy of plastic deformation that occurred locally from the boundary irregulalities to the component crystals. At 350°C or 400°C, sub-boundaries owing to the rearrangement of dislocations and subgrains were observed near the common boundary.
The initial grain boundary displacement was proportional to creep time, and the obtained activation energy for the boundary sliding of the specimen with a boundary misorientation angle ω of 43 deg. was 27600 cal/mol, which coincided well with the value of activation energy for plastic deformation by crystal slip in the aluminium single crystal.View full abstractDownload PDF (3415K) -
Hiroshi Hirano, Eiji Takahashi, Yoshiro Yamada1968 Volume 32 Issue 3 Pages 234-238
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of prior cold drawing on the mechanical properties of 0.8%C steel, patented, cold drawn and then low temperature annealed, has been studied by tensile tests, torsion tests, Charpy impact tests and fatigue tests.
The results of tensile tests after patenting show that specimens cold drawn prior to patenting (Specimen B) are stronger than those which were not cold drawn prior to patenting (Specimen A). Also, the pearlitic structure of specimen B is finer than that of specimen A. The austenite grain size of specimen A is larger than that of specimen B.
After patenting, the specimens were cold drawn and low temperature annealed at 100°∼640°C. Specimen B is stronger than specimen A after these treatments as well as after patenting. Elongation and reduction in area of specimen A are larger than those of specimen B, but the number of torsion of specimen B is smaller than that of specimen A.
Charpy impact results show that the absorbed energy of specimen B is larger than that of specimen A when both specimens were annealed at temperatures between room temperature and 250°C, but, when they were annealed at 300°∼400°C, this tendency becomes reversed.View full abstractDownload PDF (1675K) -
Hiroshi Hirano, Eiji Takahashi, Yoshiro Yamada1968 Volume 32 Issue 3 Pages 238-243
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe austenite grain size of 0.8% Carbon steel specimen was varied as a function of reduction in area of prior cold drawing, austenitizing temperature and austenitizing time in order to study the effect of austenite grain size upon the strength of the specimen after isothermal reaction at 510°∼580°C.
After these treatments, all the specimens were tensile tested and some of them were observed by an electron microscope. As the reduction in area increases at prior cold drawing, the austenite grain size of the specimen becomes smaller during subsequent austenitizing, and the strength of the specimen increases after an isothermal reaction. When the austenite grain size just prior to quenching into lead bath is small, the strength of the as-patented specimen becomes higher even if the specimen was not cold drawn prior to patenting. At patenting, the lowering of the quenching temperature without changing the austenite grain size results in a slight strengthening of the specimen. As the austenite grain size changes just prior to quenching into a lead bath, the morphology of the resultant pearlite also changes; for example, prior cold drawing makes the as-patented structure of the specimen more semipearlitic and less lamellar pearlitic. This semi-pearlite which contains very fine, dispersed non-lamellar cementite compared to lamellar cementite is thought to contribute to the strengthening of the specimens which were cold drawn prior to patenting.View full abstractDownload PDF (2522K) -
Akira Suzuki, Shushi Kinoshita, Shoji Yoshida1968 Volume 32 Issue 3 Pages 244-247
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe rates of growth of pearlite and thermodynamic quantities in commercial medium plane carbon steel and medium carbon, 0.25% chromium steel have been measured as a function of the reaction temperature.
These data have been correlated in terms of the rate equation derived by Frye et al. with an application of the absolute rate theory.
Activation energies for the growth of pearlite are reported to be 63000 cal/mol for the carbon steel and 64000 cal/mol for the chromium steel, from which it is evident that diffusion of carbon is not a rate-determining mechanism.View full abstractDownload PDF (1470K) -
Mitsuru Ishii1968 Volume 32 Issue 3 Pages 248-254
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMild steel containing 0.17% carbon was impactly extruded at temperatures up to 1000°C, and the structures and the mechanical properties of the extruded rods were investigated. It was found that the properties of the extruded mild steel varied considerably depending on the extrusion temperature and the extrusion ratio, perhaps due to the adiabatic deformation taking place in the impact extrusion. The critical temperature at which the extruded mild steel contains a recrystallized ferrite structure is lowered from 600°C to 400°C by increasing the extrusion ratio from 2.0 to 6.6. The extrusion temperature at which ferrite and pearlite are austenized during the extrusion is also lowered by 100°∼200°C by the same variation of the extrusion ratio. The sample extruded at the temperatures of the (α+γ) range is composed of coarse ferrite grains with uniformly dispersed fine pearlite. The mechanical properties of the mild steel extruded in this temperature range severly depend on the temperature. The extrusion at 750° and 700°C lowers the yield stress and the tensile strength respectively. While the extrusion at 800°C brings the maximum yield and tensile strength.
Structural observation proves that the yield stress is mainly determined by the shape and the distribution of ferrite, the tensile strength by those of pearlite, and the elongation by both ferrite and pearlite, respectively. When the extrusion ratio is selected exceedingly small or large, pearlite always distributes uniformly in ferrite of the matrix, which explains why the unusual changes of mechanical properties associated with the extrusion temperature do not take place in these cases.View full abstractDownload PDF (3332K) -
Mitsuru Ishii1968 Volume 32 Issue 3 Pages 254-258
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe behaviors of impact extrusion in three kinds of metals with different density were investigated at impact velocities from 4.5 to 6.2 m/sec and varying extrusion ratios of 2.6 to 60.0. It was found that the observed initial punch pressure at high extrusion ratio became exceedingly large due to the inertia resistance force pR of ρ(vR)2⁄2g, where ρ is the density of metal, v the punch velocity, R the extrusion ratio and g the gravity constant, respectively. On the contrary, the observed final punch pressure for the high extrusion ratio was found to decrease by the inertia drawing force of ρaRl⁄g which is the tensile stress acting on the load cell system (the punch) and arises due to the inertia force of the running extruded rod of length l at the decelerating rate of a·R, (a is the decelerating rate of the punch).
In the impact extrusion of metals with high density at a high extrusion ratio, these two kinds of extra force become important and usually the punch pressure decreases rapidly with the punch stroke (or time). The critical velocities vc·R at which the inertia parting takes place are found to be 320 m/sec for Al at room temperature and 120 m/sec for Cu at 600°C, respectively. In other words, the tensile stress due to the inertia force exceeds the tensile strength of Al and Cu at R=60 and 35, respectively, when they are extruded at the punch velocity of 6.2 m/sec. In the case of Pb the inertia parting takes place more easily due to the large density and the low tensile strength of this metal. Due to the easiness for the inertia parting to occur in this case, the effect of inertia force on the final punch pressure does not appear.View full abstractDownload PDF (1781K) -
Mitsuru Ishii1968 Volume 32 Issue 3 Pages 259-263
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe behaviors of impact extrusion of Al and Cu were investigated at a constant extrusion ratio, i.e. 47.4 for Al and 19.6 for Cu, and at varying punch velocities of 6.2 to 10.8 m/sec. When extruded at high punch velocity, the inertia resistance and drawing forces becomes measurable. As a result the initial punch pressure is found to increase and the final punch pressure to decrease, and the difference of the initial and final punch pressures increases with increasing punch velocity. The critical velocities vcR at which the inertia parting takes place are found to be 324∼351 m/sec for Al at room temperature and 204∼211 m/sec for Cu at 400°C, respectively. It was confirmed that the inertia parting was detectable on the punch pressure vs. stroke curve as a sharp rise of pressure of the order of calculated inertia force. These observations predict that, in the impact extrusion at high velocity, metals show hydrodynamic behaviors. Finally the extrusion by multi-oriffice die is confirmed to be profitable for the extrusion of dense metals, making both the inertia force and the punch pressure small and avoiding the inertia parting to occur.View full abstractDownload PDF (2003K) -
Tohei Ototani, Yasuzi Kataura1968 Volume 32 Issue 3 Pages 263-266
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of molybdenum on the graphitization and mechanical properties of calcium wrought graphite steel containing about 1.3%C and 0.8%Si were investigated. The suitable annealing temperature for the graphitization has been found to be in the range from 800° to 900°C. Graphitization was considerably suppressed depending upon the amount of molybdenum as the carbide forming element and also the hardness increased. The upper molybdenum limit may be considered as 0.3%, of which this element insures the precipitation of necessary graphite and the strength of the matrix. Mechanical properties of calcium treated Graph-Mo steels were closely related to the microstructures, which in turn depend upon oil quenching, the tempering temperature and the resulting combined carbon.View full abstractDownload PDF (1485K) -
Tohei Ototani, Yasuzi Kataura1968 Volume 32 Issue 3 Pages 267-271
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study has been made on the graphitization and mechanical properties of the calcium treated graphite steel containing 0.57∼1.78%Mn, 0.26∼1.41%Cr, 0.37∼1.83%Ni or 0.32∼1.63%Cu. Where carbide forming elements such as manganese and chromium are present over 1% in the former and over 0.5% in the latter, the graphitization has been considerably suppressed. When the amount of nickel and copper increased, the carbide phase was more unstable than the common graphite steel. From mechanical properties of heat-treated alloy graphite steels it has been inferred that suitable additions of manganese and chromium are effective for improvement in wear resistance, and additions of nickel and copper improve ductility and machinability, respectively.View full abstractDownload PDF (1290K) -
Hideo Abe, Kineo Takagi1968 Volume 32 Issue 3 Pages 271-276
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe cold-rolling and annealing textures of a low carbon steel processed by two stages of cold-rolling which were separated by an intermediate annealing were investigated. As previously reported, the (110)[001] component in the annealing texture of the intermediately annealed sheet was remarkably increased by quenching the hot strip from 715°C before the first stage cold-rolling. By quenching the intermediately annealed sheet from 715°C followed by cold-rolling to a reduction of approximately 60%, the (110)[001] component rotated to the {111}⟨112⟩ orientation and from this orientation a sharp (110)[001] type texture was produced by the final annealing at 700°C. The (110)[001] component in the finally annealed sheet increased during the grain growth on annealing at 800°C for 1 hr.View full abstractDownload PDF (1633K) -
Shin-ichiro Muroi, Mayumi Someno1968 Volume 32 Issue 3 Pages 276-282
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of alloying elements, especially of silicon, on the attack of steels by vanadium pentoxide were studied by the attack tests of Cr steel, Ni-Cr steels, Cr-Si steel and Fe-Si alloys. Weight changes of specimens were measured with the following results:
(1) There were little differences in the resistance against the attack between 12%Cr steel and Cr-Ni steels over the temperature range of 750°∼820°C. But above 850°C, 12%Cr steel was attacked heavier than Cr-Ni steels. These results were disscussed with binary phase diagrams of the oxides.
(2) 8%Cr-3%Si steel was superior to 12%Cr steel and 17%Cr-13%Ni steel in the resistance against the attack. Fe-Si alloys were more resistant as the silicon content increased. Therefore, it can be concluded that silicon has a favourable effect on the resistance against the attack.
The siliconizing method of steel with SiCl4 was investigated in H2 atmosphere, and the method to obtain a poreless and silicon-rich surface was established for 12%Cr steel. The resistance of 12%Cr steel against the attack can be increased by siliconizing.View full abstractDownload PDF (2440K) -
Tadayuki Nakayama, Tatsuya Koizumi1968 Volume 32 Issue 3 Pages 282-288
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe passivity of titanium, especially the passivity in boiling H2SO4, HCl, and HNO3, and oxide films formed on passivated surfaces are investigated. Titanium was naturally passivated in dilute H2SO4 (≤0.1 wt%) and HCl (≤0.2 wt%), and in HNO3 with any concentration up to concentrated acid. The passivated surfaces were covered with thin oxide films, and titanium attacked by H2SO4 and HCl with higher concentrations was covered with the titanium hydride layer.
Basic electrochemical data, e.g., corrosion potential vs. time curves, anodic polarization curves and Flade potential vs. pH curves, were obtained in those acid solutions with various concentrations. In the reducing acid solutions, the polarization curves have a typical shape with the transition from the active to the passive region. The relations between Flade potential and pH of the solutions were expressed as Ef(h)=0.19∼0.20 pH for H2SO4 and Ef(h)=−0.05∼0.19 pH for HCl.
The structure and composition of oxide films formed on naturally and electrochemically passivated surfaces were studied by means of electron microscopy and diffraction. They were composed of thin continuous films derived from the anodic oxidation of metallic titanium and fine deposited oxide. Three modifications of TiO2, i.e., rutile, anatase, and brookite, were detected, and further a difference in oxide modification was found in different acids.View full abstractDownload PDF (3003K) -
Isao Gokyu, Teruo Kishi, Satoru Ogura1968 Volume 32 Issue 3 Pages 289-294
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHigh strength steel can be produced by the straightening process in the warm-working temperature range. In this investigation, in addition to mechanical properties of straightening steel, the deformation mechanism of high carbon steel in the warm-working temperature range is discussed.
The results are as follows:
(1) As for as-rolled steel, 0.2% proof stress and tensile strength of warm-worked steel are 50% and 10% higher than those of cold-worked steel.
(2) As for 60% cold-drawn steel, the strength of cold-worked steel considerably decreases, while the strength of warm-worked steel increased. The 0.2% proof stress is 150∼170 kg/mm2 and the tensile strength is 170∼190 kg/mm2. The strength difference by both treatments is about 40∼50 kg/mm2 in 0.2% proof stress and 15∼20 kg/mm2 in tensile strength. The effect of low temperature annealing is recognized, but less than the warm-working effect. Moreover, the relaxation value is especially excellent and elongation is enough.
(3) The activation energy in the warm-working temperature range is about 20 kcal/mol, which is obtained from the strain rate variation in the compressional test. This value is equal to the activation energy of carbon and nitrogen diffusion in ferrite, therefore, it is reasonable to consider that the flow stress increase of high carbon steel depends on the diffusion of C and N. With this activation energy, the authors calculated the moderate warm-working temperature for straightening, and obtained good agreement with the experimental temperature range.
(4) It was shown that even in the as-rolled specimen 2/3 of the strength increase is due to the increase of work-hardening and 1/3 due to the decrease of the Bauschinger effect.
Therefore, for the cold drawn wire, the variation in strength during straightening mainly results in the softening due to the Bauschinger effect.View full abstractDownload PDF (2258K) -
Goro Ito, Tadao Ishihara, Yoshihiko Shimizu1968 Volume 32 Issue 3 Pages 295-300
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effects of alloying elements on the susceptibility of austenitic stainless steels to stress corrosion cracking in high temperature water were investigated.
Tests were made at 300°C for 300 hr in an autoclave containing the testing water with 600 ppm of chloride ion added as NaCl.
The results were summarized as follows:
(1) All of the tested austenitic stainless steels with limited amounts of impurities, such as P,S,Mn and so on were resistant to stress corrosion cracking than commercial stainless steels except for the case of 18Cr-8Ni with low nitrogen content.
(2) The additions of Si, V, Mo and Re to 19Cr-9Ni stainless steels were highly effective in increasing the resistance to pitting corrosion of steels, and among those elements V and Mo had a positive effect on the improvement in resistance to stress corrosion cracking, but other two elements, Si and Re, were no use for that purpose. On the other hand, though alloys with Al had a negative effect on the resistance to pitting corrosion, they did not crack.
(3) Alloys specimens containing 18 per cent chromium and 8 per cent nickel failed with additions of nitrogen below approximately 0.03 per cent. As the amount of martensite in these two-phase alloys containing a mixture of martensite and austenite increased, the alloys showed intergranular cracking which was attributable to hydrogen embrittlement.
(4) In the alloys except 18Cr-8Ni, effects of nitrogen in the range of approximately 0.003 to 0.10 per cent on the susceptibility to pitting corrosion and stress corrosion cracking were not noticed.
(5) As the nickel content in alloys containing 18 per cent chromium increased from 8 per cent to 20 per cent, the susceptibility of the alloys to stress corrosion cracking decreased.
(6) Since electropolished specimens were resistant to cracking and also to pitting corrosion compared with paper-ground specimens, it appears that the removal of a surface residual stress layer or the formation of a protective film on specimens in the process of electropolishing is a probable factor causing the difference in resistance to stress corrosion cracking.
(7) The results of tests as to the effect of alloying elements on the susceptibility of stainless steels to stress corrosion cracking, did not coincide with that in a boiling 42 per cent magnesium chloride aqueous solution and in high temperature water.View full abstractDownload PDF (2220K) -
Wataru Suëtaka1968 Volume 32 Issue 3 Pages 301
Published: 1968
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (412K)
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