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Volume 30, Issue 12
Displaying 1-12 of 12 articles from this issue
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Shoich TAKAYAMA1980 Volume 30 Issue 12 Pages 677-678
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
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Ryuzo SUZUKI, Takao SHIBATA, Hideo NAGASAKA1980 Volume 30 Issue 12 Pages 679-683
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSThe corrosion potential, polarization behavior and corrosion rate of Al, Al-78 and 85%Zn alloys and Zn sprayed films in a 3% NaCl solution were electrochemically examined at 25°C. The polarization characteristics were measured by means of potentiodynamic and potentiostatic methods. The corrosion rate was determined from the intersection of local anodic and cathodic polarization curves. The Al and Al-78%Zn alloy sprayed films have almost identical corrosion potentials, and the Zn and Al-85%Zn alloy sprayed films also do so. The anodic and cathodic polarization curves of the Al-Zn alloy sprayed films are similar to those of the Zn sprayed film. Zn in the alloy preferably dissolves in the anodic polarization process. Increase in polarizing current is retarded by oxide films formed on the surface of Al matrix. The estimated corrosion rates of Al, Al-78%Zn, Al-85%Zn and Zn sprayed films are about 2, 20, 16 and 26 μA/cm2 respectively.View full abstractDownload PDF (3718K) -
Motohiro KANNO, Hisashi SUZUKI, Osamu KANOH1980 Volume 30 Issue 12 Pages 684-693
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSAging phenomena of Al-4%Cu alloys containing Mn up to 0.5% were studied. Two types of solution treatments, normal treatment at 520°C for 2 hr and special treatment at 520°C for 1 hr after annealing at 560°C for a week, were made. Specimens were aged mainly at 200°C. The initial aging rate and age-hardenability of the ternary alloys normally treated reduce with increasing Mn content. This fact is well understood basing on the fact that the density of dislocation loops acting as nucleation sites for θ' phases decreases, because dispersed insoluble phases as sinks of excess vacancies form. The initial aging behavior of the ternary alloys up to 0.3%Mn specially treated is nearly the same as in the binary alloy resulted from disappearance of the insoluble phases. The aging rate of the ternary alloys is considerably retarded after prolonged aging with increasing Mn content accompanying by asharp suppression in the growth rate of θ' phases. The mechanism is discussed in relation to Mn atoms having extremely low diffusion coefficient in the aluminium matrix.View full abstractDownload PDF (25344K) -
Shuhei OHSAKI, Yo KOJIMA, Tsuneo TAKAHASHI1980 Volume 30 Issue 12 Pages 694-700
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSThe effect of aging conditions was investigated metallurgically and electrochemically. Two types of intergranular corrosion are observed in the alloy cold aged at a temperature below 100°C for a short period and in one warm aged at a higher temperature or for a longer period. The former intergranular corrosion occurs due to preferential breakdown of an anodic grain boundary zone. While the latter occurs due to selective dissolution of grain boundary precipitated particles resulting in pit-type intergranular corrosion. SCC in the cold aged alloy is closely related to intergranular corrosion. It occurs by stress-assisted intergranular corrosion. SCC in the warm aged alloy proceeds by the two-step mechanism combining an electrochemical process and a mechanical defor mation processView full abstractDownload PDF (7670K) -
Takio TANAKA1980 Volume 30 Issue 12 Pages 701-706
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSThe alloys containing Zn+Mg 4.5, 6.0 and 7.5% at different Mg/(Zn+Mg) ratios were examined. The alloys containing a constant amount of Zn+ Mg at Mg/(Zn+Mg) ratio 0.3 show the best surface finish. The reason is that the built-up edge formation and the tool-chip contact length of the alloys are remarkably decreased with increasing the ratio less than about 0.3 and are increased with increasing the ratio more than about 0.3. The finished surfaces of the alloys with the ratio 0.3 are superior to those of Al-Mg alloys which are equivalent to those of Al-Zn-Mg alloys with the ratio 1.View full abstractDownload PDF (4929K) -
Takao ENDO, Yoshihiro IBARAKI, Masaharu TASAKI1980 Volume 30 Issue 12 Pages 707-712
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSThe change in static flow stress caused by superimposed ultrasonics (17.8 kHz) during testing was studied at 77 and 300 K under the strain rates and oscillatory stress amplitudes from 8.3×10-6 to 8.3×10-4/s and from 0.2 to 11 MPa respectively. The temperature rise due to application of ultrasonics is smaller than 6 K, when the application time is less than 10 s. The decrements in static flow stress Δσ are independent of strain rates, temperatures and stresses at which the stress superimposition is carried out. The relation between Δσ and stress amplitude Δσv°is empirically expressed;Δσ=qΔσv°, where q is a constant equal to 0.7, although the theory based on the stress superimposition mechanism predicts that the value of q is equal to unity. The reason for this discrepancy between the theory and experiments is discussed.View full abstractDownload PDF (3272K) -
Yutaka NAKAYAMA, Sadahiro ONIMARU, Kenji MORII1980 Volume 30 Issue 12 Pages 713-719
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSThe (211) [111] single crystals were rolled at room temperature. The effect of shear banding on the deformation behavior of the crystals were metallographically examined. Shear bands are induced in the crystals rolled 50% or more without mechanical twinning. The initial shear bands are of wavy slip bands deviated from the traces of a {111} slip plane. These slip bands are generated closely with each other and developed into the shear bands as the rolling reduction increases. The shear bands are composed of sheet-like regions which are disposed perpendicular to the side surface and inclined about 30 to 35° to the rolling plane of the crystal. The mechanism of shear band formation and the stability of the (211) [111] orientation are discussed.View full abstractDownload PDF (11516K) -
Koichi YAMADA1980 Volume 30 Issue 12 Pages 720-726
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
JOURNAL FREE ACCESSEffects of sodium hydroxide and alumina concentrations, temperature and seed quantity on the numerical change of crystals during crystallization of aluminum trihydroxide were studied. The ratio of the crystal numbers before and after crystallization Ne/No is correlated with initial supersaturation degree S.D, temperature T (K) and surface area of seed A (m2/l) :
Ne/No=0.8 × 100.91 Z2 and Z=S. D-log A2-0.005T+2.5 Only the agglomeration between fine particles less than 10, um is observed by using the seed doped with gallium with respect to agglomeration behaviors.View full abstractDownload PDF (2894K) -
Mitsugu MOTOMURA1980 Volume 30 Issue 12 Pages 727-735
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
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Shigetake IMAIZUMI, Masami ASANO, Masaru OKUFUJI1980 Volume 30 Issue 12 Pages 736-753
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
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Naochika TORIKAI, Takeshi MEGURO, Yoshitaka KOBAYASHI1980 Volume 30 Issue 12 Pages 754-760
Published: December 30, 1980
Released on J-STAGE: March 14, 2011
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1980 Volume 30 Issue 12 Pages e1
Published: 1980
Released on J-STAGE: March 14, 2011
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