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Volume 44, Issue 7
Displaying 1-18 of 18 articles from this issue
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Masato Murata, Yoshihiko Mukai1980 Volume 44 Issue 7 Pages 713-722
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the previous paper, it was reported that stress corrosion cracking (SCC) of austenitic stainless steels in various environments were divided into the following groups; A group (SCC in the strict sense), Transition group, B group (SCC with corrosion cracking characteristics).
In the present paper, the mechanism of SCC in several groups were studied by fractography. As the results, in A group, fracture planes in SCC were constituted mainly by {100} planes and SCC growth direction was sensitive to the principal stress. In transition group and B group, fracture planes in SCC were constituted mainly by {111} planes. In B group SCC, growth direction was also sensitive to shear stress. The selectivity of the fracture planes and the stress dependency of SCC seem to be closely related to the corrosiveness of environments.View full abstractDownload PDF (1805K) -
Katsushige Tsuno, Tadami Taoka1980 Volume 44 Issue 7 Pages 723-728
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of the ferromagnetic anisotropy of an iron pole piece material on the homogeneity of magnetic field in electromagnets depends on the origins by which the anisotropy has been introduced. The biaxial and uniaxial anisotropies arising from an anisotropic distribution of crystal grains have no effect on the homogeneity of magnetic field, while the uniaxial anisotropy originating in the anisotropic distribution of the crystalline and metallurgical defects gives a marked effect on the homogeneity. The latter anisotropy is introduced in working processes at elevated temperatures and can be minimized by forging the materials at a temperature lower than the A3 transformation point of the pole piece material.View full abstractDownload PDF (509K) -
Kozo Kitada, Fumiyoshi Miyashita, Giroku Miyatani, Toshio Miyake, Tuyo ...1980 Volume 44 Issue 7 Pages 728-734
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe reaction between chromium oxide and chromium carbide which formed metallic chromium was carried out in a high vacuum of 1.01325∼0.101325 Pa at temperatures ranging from 1273 to 1593 K. Mixture of 2 moles of Cr2O3 and 1 mole of Cr23C6 was pelleted and reduced under the above-mentioned conditions.
The experimental results were summarized as follows:
(1) The reaction started at about 1353 K. This result corresponded approximately to the thermodynamic data.
(2) The reaction velocity increased with reduction of specific surface area. It conjectured that indirect gaseous reactions predominated.
(3) The reaction proceeded from the surface to the inside of the pellets. At the earlier stages of the reactions, a rate equation for interfacial reaction control was applicable, but at the later stages of the reaction, the rate determining step was observed as diffusion reaction.
(4) Judging from the isothermal TGA and formed metallic layer of section of pellets, at the interfacial reaction, the activation energy was estimated at 188±13 kJ/mol.View full abstractDownload PDF (710K) -
Shigeo Matsushima1980 Volume 44 Issue 7 Pages 734-740
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFatigue deformation and fracture strength have been studied by tension-compression fatigue tests of Cu-5%Al alloy on the assumption that the damage accumlation can be shown by Coffin’s formula. The discussion of the fatigue strength is supported by the microscopic observation on the slip lines. The results obtained are as follows: (1) The relation between maximum value σ0 of cyclic stress and number N of stress cycles to failure is derived as αm(σ0m\barn−σfm\barn)N=C for σ0>σf(=7.8×107 Pa), where α, C, m and \barn are 5.59×10−39 Pa−\barn, 9.32×10−2, 2.32 and 4.43, respectively. This relation is confirmed by the fatigue tests. (2) The slip lines made in one cyclic stress decrease with the increase of the number of stress cycles.View full abstractDownload PDF (1127K) -
Akio Tanaka, Takashi Nakamura, Yasuaki Ueda, Fumio Noguchi1980 Volume 44 Issue 7 Pages 741-748
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe morphology of electrodeposition of zinc on the cathodes of zinc and aluminum single crystals from sulfuric acid solution was investigated under galvanostatic conditions at current densities of 0.2∼1.5 kA/m2. The cathode polarization curves and the amounts of generated hydrogen were measured and the morphologies of the deposits were observed with a scanning electron microscope. The results were summarized as follows.
(1) The overvoltage of zinc deposition and the generation rate of hydrogen on aluminum single crystal were found to increase in the order of (111)>(100)>(110) planes. This increasing order shows the same order of magnitude in atomic density of the plane. The overvoltage and the generation rate of hydrogen on zinc single crystal increased in the order of (0001)>(11\bar20)>(1\bar100) planes.
(2) Epitaxy was observed on aluminum single crystal only at lower current density (20 A/m2), most of zinc deposits grew incoherently with the substrate.
(3) The deposition of zinc on zinc single crystal showed epitaxial growth up to a high current density of 1 kA/m2. As the morphology zinc deposits varied with the orientation of the substrate plane. Layer growth and facets were observed on the (0001) plane. Layer and ridge growth was observed with an occasional formation of facets on the (11\bar20) plane.View full abstractDownload PDF (969K) -
Jun Ikeuchi, Motofumi Homma, Hideo Kaneko1980 Volume 44 Issue 7 Pages 749-756
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is known that the corrosion rate of metals is accelerated in the oxidative corrosion due to V2O5 melts. Although a relatively large number of papers dealing with oil-ash corrosion of commercial heat resistant alloys have been published, little progress has been made to elucidate the mechanism of corrosion, because of the complexity of factors encountered in the corrosive environment. Here, a simple corrosion model was proposed on the basis of the assumption that both growth and dissolution of the corrosion layer at the V2O5/oxide interface occur simultaneously. According to the model, the equations on the rate of metal recession were derived. These equations were applied to the corrosion of Fe, Cr and Ni, and the rate of metal recession estimated was in good agreement with experimental data. The parabolic growth rate constant of the corrosion layer (kd) and the dissolution rate constant (ks) were calculated from another equation derived from the same model, which relates the thickness of corrosion layer to kd and ks. The results obtained were as follows:
(1) The ks is dependent on the species of metals. The ks of iron is twice as large as that of chromium or nickel.
(2) The kd of the corrosion layer on chromium or nickel is much larger than that of Cr2O3 or NiO on the surface of the metals in the atmosphere. The kd on chromium or nickel is about one-tenth compared to that on iron which is 5×10−13 m2/s.
As a result, the weight loss of chromium or nickel due to V2O5 melts becomes one-fifth compared to that of iron.View full abstractDownload PDF (1086K) -
Tokuzou Tsujimoto1980 Volume 44 Issue 7 Pages 757-763
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor alloys whose free energy is given by [(ce−0.5)2−(c−0.5)2]2×const., interdiffusion coefficient, \ ildeD, of solid solution including composition variation of q(x, t)=c(x, t)−c0 can be written as \ ildeD(x, t)=D0−D1q(x, t)+D2q2(x, t) where c0(<0.5) and ce are the average and equilibrium compositions respectively. The diffusion equation is, for such a case, written in Fourier space as
(This article is not displayable. Please see full text pdf.)
\ oindentwhere F(h) is a Fourier spectrum representing a composition variation. G(h) and H(h) are functions obtained by convoluting F(h) once and twice, respectively. hβ represents wavenumber of Fourier waves and K is (gradient energy coefficient)×(mobility of atoms). The value of D0 increases with decrease in c0, and it is positive for alloys of c0<cs (spinodal composition). D1 is zero at c0=0.5 and increases with decrease in c0, while D2 is constant for all alloy compositions.
Through the diffusion process, the second term of eq. (1) and the third term produce the harmonic Fourier spectra with the components of the same sign and those of alternating sign, respectively. In composition variations of small amplitude behavior of F(h) is controlled by the first term. With increase in amplitude the controlling term for F(h) changes from the first to the second term, and then to the third term. The following results are obtained by numerical calculation of eq. (1). Composition variations in alloys of c0>cs amplify spinodally by virtue of the first term, while in alloys of c0<cs they change their configrations to those of nuclei by virtue of the second term after some incubation time. Composition variation peaks are squared and nuclei grow by virtue of the third term at a later stage of decomposition. The required condition for the formation of nuclei is that a part of composition variation exceeds cs.View full abstractDownload PDF (575K) -
Kazuyoshi Hatano, Hachiro Honma, Katsuro Abe, Eiji Kometani1980 Volume 44 Issue 7 Pages 764-769
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe heat treatment characteristics and rolling contact strength of induction hardened bearing steels were studied in comparision with those obtained by conventional quenching.
Rapid heating tests were done at heating temperatures from 1073 to 1163 K and with holding times from 10 to 1500 s. Rolling contact tests were done under the lubricated pure rolling conditions using cylinder test pieces and balls. The contact stresses were from 5200 to 6000 MPa.
The results obtained were as follows.
(1) In the case of rapid heating, satisfactory material properties were obtained at a heating temperature of 1133 K and with a holding time of 60 s.
(2) Rolling contact strength of induction hardened bearing steels was nearly equal to those obtained by conventional quenching.
(3) Depth of pittings was approximately two times deeper than the maximum shear stress position.View full abstractDownload PDF (701K) -
Masaru Yokota, Masateru Nose, Yoshishige Takano, Hiroyasu Mitani1980 Volume 44 Issue 7 Pages 770-775
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInvestigations of the wettability and the interaction between solids and liquids in Cu-Sn binary system were carried out in the atmosphere of dry hydrogen gas flow by coupling solid pure copper, ε(Cu3Sn) and η(Cu6Sn5) alloy plates with liquid pure tin and Sn-Cu alloys respectively. The results obtained were as follows:
(1) Wetting angle between solid pure copper and liquid pure tin showed a tendency to decrease with the passage of time at the temperature between 523 and 623 K. On the contrary, wetting angle between solid pure copper and liquid pure tin more than 623 K or that between solid alloy plates (ε or η) and liquid drops (pure tin or Sn-Cu alloy) at the temperature between 573 and 773 K did not have the time dependency.
(2) Wetting angle between solid pure copper and liquid pure tin showed a remarkable discontinuity in the vicinity of peritectic temperature (η=ε+melt); from our experiment it is reasonable to consider that the above peritectic temperature is higher than that of already known 668 K.
(3) At each temperature in the present experiment, it has been clarified that the smaller the defference of concentration between solid and liquid in Cu-Sn binary system, the smaller the wetting angle; in other words, the nearer the concentration of solid plates to that of liquid drops, the more wettable.View full abstractDownload PDF (592K) -
Hisashi Kawabe, Kaizo Kuwahara1980 Volume 44 Issue 7 Pages 776-782
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStrain-amplitude (γ) dependence of internal friction (Q−1) and rigidity modulus (f2) in ferromagnetic metals (SIA and Ni) has been investigated by the inverted torsion pendulum method as functions of tensile stress (σl) and magnetic field (H).
In SIA, curves of Q−1 and f2 vs γ are characterized by a function of convex type, which has a maximum (Q−1max=0.023) at the surface shear γ\simeq6×10−5, and by a function of concave type having a minimum (f2min) at nearly the same γ as at Q−1max, respectively. The γp′ and γp″, which stand for the respective γ levels at Q−1max and f2min, coincide with each other at σl=0, whereas with increasing σl they gradually separate making themselves larger, and for σl\gtrsim100 MPa, yield a rough relation, γp′\simeq2γp″. The damping properties as a function of H also has a similar tendency. On the other hand, in Ni, the damping maximum is not observed so clearly as in SIA, and its Q−1max is considerably low (Q−1max=0.009 at γp′\simeq3×10−4). The variation of γp′ with increasing σl and H leads mainly to the change in Hc (coercive force), and therefore the difference in the damping property between Ni and SIA may also be ascribed to the relative magnitude of Hc.
While there has so far been given a qualitative relationship that Q−1∝γ at γ<γp′, the Q−1 vs γ (<γp′) is more likely described by a quadratic increasing function due to ΔG-effect than by a linear increasing one, and the greater the ΔG-effect, the more noticeable becomes such an increasing tendency of Q−1.View full abstractDownload PDF (523K) -
Hiroshi Yamagata, Osamu Izumi1980 Volume 44 Issue 7 Pages 782-789
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the mechanism of anneal-hardening, the change of yielding behavior of tensile prestrained 70/30 brass single crystal was studied. On reloading, after annealing, the yield stress was observed to increase higher than the final flow stress (σp) just before unloading, and the yield stress increment (Δσ) ratio (defined as (100Δσ⁄σp) showed two maxima against the prestrain values. One of the two maxima was observed in the prestrain range at the initial part of stage 1 hardening (<0.1 in shear strain) and correlated with a simple strain aging mechanism. The other was observed in the prestrain range at the initial part of stage 2 hardening and explained by the characteristics of Lomer-Cottrell sessile dislocation. With increasing the annealing time, these two values showed a single maximum, but if an arbitrary prestrain was taken the ratio (100Δσ⁄σp) showed oscillating behaviors against annealing time. Especially at a prestrain of about 0.3 in shear strain the ratio (100Δσ⁄σp) showed an under damped oscillation. These behaviors were discussed from the viewpoint of the stability of dislocation structure and the work hardening mechanism.View full abstractDownload PDF (713K) -
Hiroshi Yamagata, Osamu Izumi1980 Volume 44 Issue 7 Pages 790-799
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe low temperature anneal-hardeninig of α-brass polycrystals was studied. The special aim of the present work is to make clear the relation between the degree of anneal-hardening and the amount of cold working. The main results are as follows. The increase in hardness with increasing the amount of cold-working was not continuous, but the discontinuous and abrupt increases of hardness were observed at certain strains. In tensile prestrained specimens, the Bauschinger effect measured by compression test was pronounced with increasing the prestrain as a whole, but it became inconspicuous transitorily at the prestrains where the abrupt increases of hardness were observed.
In both tensile test and rolling these special strain values where the abrupt increases of hardness were observed coincided with the strains at which the work-hardening characteristics changed. Especially in rolling, the hardening additional to the usual three stage hardening in FCC metals, were further observed at higher strain ranges, corresponding to the occurrence of deformation twins, macroscopic shear bands, respectively.
In these prestrain values at which the abrupt increases of hardness appeared, the amount of annel-hardening were smaller than the intermediate prestrain of each stage. Moreover, the compressive yield stress of tensile prestrained specimens also showed minimum values after annealing. These behaviors were discussed from the view point of the stability of dislocation structures.View full abstractDownload PDF (924K) -
Masamichi Kowaka, Kazuo Yamanaka1980 Volume 44 Issue 7 Pages 800-808
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of alloying elements on the propagation rate of stress corrosion cracking and threshold stress intensity factor for stress corrosion cracking (KISCC) of austenitic stainless steels has been investigated in boiling MgCl2 solutions. The fracture surface was investigated fractographically by scanning electron microscopy. The results obtained are as follows:
(1) KISCC was about 3 MPa\sqrtm (10 kgf/mm3⁄2) for SUS 304 stainless steels containing below about 0.020 mass%P and decreased with increasing the amount of phosphorus above 0.020 mass% in boiling 45%MgCl2 solution.
The propagation rate of stress corrosion cracking increased with the increase in phosphorus content.
(2) The increase molybdenum and nitrogen content decreased KISCC and increased the propagation of stress corrosion cracking in boiling 42% and 40%MgCl2 solutions, respectively.
(3) Sulfur in the composition range of 0.008∼0.038 mass% had no significant influence on KISCC and the propagation rate of stress corrosion cracking in boiling 45%MgCl2 solution.
(4) It was found that the fracture surface of SCC was transgranular and composed of {100} and {110} planes, which was determined by the morphology of etch pits.View full abstractDownload PDF (1559K) -
Hiroki Ohno, Shuji Nakano, Osamu Miyakawa, Koichi Watanabe, Nobuhiro S ...1980 Volume 44 Issue 7 Pages 809-814
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe present paper has revealed the difference of microstructural characteristics between the metallurgical structure formed by discrepancies of sputtering yield in the ion-etching and that formed by differences of the electrochemical potential in the chemical etching on precious metals and alloys, and appreciated superiorities or inferiorities of the ion sputtering as an etching technique in metallography.
The contrast in an optical micrograph arises mainly from a preferential attack of the grain boundary in the chemical etching, while in the ion-etching it is produced by the steps of the grains which are parallel to the polishing surfaces and are dependent on crystal orientation and composition. In the optical microscopic observation, the ion-etching method can obtain the clear contrast which is not at all inferior to that of the chemical etching. Besides its usefulness as an etching method for the specimens which can not etch chemically, the method can control easily amounts of etching, has good reproducibility of the etching images, and does not require proficient and empirical techniques in comparison with the chemical one.View full abstractDownload PDF (1483K) -
Saburou Kuwano, Mamoru Anma, Takeo Oki1980 Volume 44 Issue 7 Pages 815-822
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAlthough there have been many electrochemical studies in stress corrosion cracking (SCC) of metals, there have been very few investigations in which the susceptibility was inspected in conjunction with their polarization behavior.
Therefore, in this paper, the effect of the applied stress on the polarization behavior and the dependence of the susceptibility to SCC on potentials were measured of SUS 304 type stain-less steel in 42%MgCl2 solution, and the relation between the polarization behavior and the susceptibility to SCC were discussed.
Moreover, the effect of the polarization on the crack morphology was observed by scanning electron microscope (SEM).
The following results were obtained:
With the applied stress over 123 MPa, the rest potentials of the specimens and the pitting potentials in the polarization curve shifted remarkably toward less noble potentials, and these changed more remarkably with increasing applied stress.
The width of the unsteady passive region decreased owing to the shift of the pitting potential mentioned above, and it disappeared at the applied stress of 294 MPa.
Three regions of the potential in which the susceptibility to SCC was different each other existed, and these regions were almost coincident with the steady passive region, the unsteady one, and the pitting region respectively.
From the results mentioned above, it was concluded that the increase of the susceptibility to SCC with increasing applied stress was attributed to both the decrease of the width or the disappearance of the unsteady passive region and the shift of the rest potential toward pitting potentials due to the applied stress.
As to the crack morphology, transgranular cracking is preferred to intergranular one in the specimens applied with anodic polarization, whereas intergranular cracking is preferred to transgranular one in the specimens applied with cathodic polatrization.
However, the dependence of the ratio of transgranular cracks to intergranular ones on the potentials under low applied stress was different from the one under high applied stress.View full abstractDownload PDF (1032K) -
Toshiaki Arato, Masanori Tokuda, Masayasu Ohtani1980 Volume 44 Issue 7 Pages 823-828
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSActivity and solubility of NiO in Na2O-B2O3-NiO melts were determined by use of EMF measurements of the following cell in the temperature range of 1123∼1373 K.
(This article is not displayable. Please see full text pdf.)
The results obtained are summarized as follows:
(1) The activity coefficient (γ°NiO) of NiO in Na2O-B2O3-NiO melts indicates positive deviation from ideality. The values of γ°NiO obtained at 1298 K for the melts with 32.5, 48, and 60 mol%Na2O were 2.5, 6.2, and 3.2, respectively.
(2) Solubility of NiO in Na2O-B2O3 melts was determined at the inflexion point on EMF vs NiO content curve and solubility lines of NiO in the Na2O-B2O3-NiO ternary system were estimated.
The maximum content of NiO (=11 mol%NiO at 1373 K) was obtained at the composition of nearly 32.5 mol%Na2O.
(3) Thermodynamic quantities of mixing of NiO were calculated by using the data of the melts containing 0.9 mol%NiO. Gibbs’s partial molar free energies of mixing of NiO were about −30∼40 kJ/mol at 1173 K and decreased with an increase in temperature and Na2O content.View full abstractDownload PDF (428K) -
Hisashi Izumi, Hisakichi Sunada, Yukio Kondo, Tohru Yamasaki1980 Volume 44 Issue 7 Pages 829-835
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of heat treatment on the plane bending fatigue strength of electroless nickel-phosphorus plated steel was explaind in terms of the difference of surface damage produced by the structural changes of plating film after heating. In addition, the structural changes of plating film after heating or cyclic stressing were investigated by X-ray diffraction and transmission electron microscopy.
The results obtained are as follows:
(1) An electroless Ni-P amorphous film had a good resistance against shear deformation during fatigue test and the existence of the amorphous film resulted in delaying the nucleation of fatigue cracks.
(2) Microcrystalline regions in the electroless Ni-P amorphous film were formed after cyclic stressing at room temperature. These regions consisted of Ni and Ni7P3 phases and seemed to be the nucleation sites for fatigue cracks.
(3) The fatigue strength decreased remarkably upon annealing for 3.6 ks at 623 K despite that the hardness of plating film increased. This decrease may be due to the increase of the embrittlement of the plating film due to the precipitation of Ni and Ni3P phases.
(4) The fatigue strength decreased remarkably upon annealing for 3.6 ks at 973 K. This improvement seemed to be due to the increase in ductility of the plating film consisting of Ni and Ni3P by grain growth and to the formation of Fe-Ni alloy layer at the interface between the plating film and the substratum.View full abstractDownload PDF (1060K) -
Ken-ichi Kanatani1980 Volume 44 Issue 7 Pages 836-837
Published: 1980
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (193K)
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