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Volume 42, Issue 1
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Hideo OGASHI1992 Volume 42 Issue 1 Pages 1-2
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (328K) -
Osamu TANNO, Kiyoaki OHUCHI, Kazuo MATUZAWA, Shigeharu KAMADO, Yo KOJI ...1992 Volume 42 Issue 1 Pages 3-9
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe effect of rare earth element (RE) on the structure and mechanical properties of Mg-8mass%Li (α+β) alloys has been investigated. RE formed intermetallic compounds with magnesium. Below 90% rolling reduction Mg-Li-RE ternary alloys showed work hardening behavior which is similar to that of Mg-Li binary alloy, while above 90% rolling reduction they exhibited the work softening probably due to recovery. Isochronal annealing below 373K softened coldrolled Mg-Li-RE alloys. On the other hand, the recrystallization temperature was raised by the addition of RE. Age-hardening due to the precipitation of α phase in β phase was observed in all alloys. Overaging was recognized in Mg-Li binary alloy, whereas not in Mg-Li-RE ternary alloys. These results suggests that RE addition improves the thermal stability of precipitates, resulting in the improvement of elevated temperature strength through aging treatment. The addition of RE tended to increase the tensile strength, but to decrease the elongation.View full abstractDownload PDF (3127K) -
Hajime KATO, Tatsumi TOZAWA, Yoshimasa TAKAYAMA1992 Volume 42 Issue 1 Pages 10-15
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSA small punch test has been carried out for the annealed specimens of six kinds of commercially pure metal sheets with 0.5mm thickness; aluminum, magnesium, titanium, zinc, copper and iron. Main results obtained are summarized as follows: (1) A Typical punch load versus punch depth curve was indicated for metals except magnesium in which the bulging deformation region was hardly observed in the punch load versus punch depth curve. (2) The magnitude of maximum punch load was in the order of Ti>Fe>Cu>Zn>Al>Mg, corresponding to the order of tensile strength for each metal except magnesium. (3) The punch depth at maximum punch load in aluminum, titaniunm, zinc, copper and iron were kept nearly constant independent of the elongation at maximum tensile strength. But the punch depth at maximum punch load was much lower in magnesium than in five other metals, (4) In magnesium the surface cracks formed at a punch depth which is much smaller than that for other metals, resulting in the brittle fracture.View full abstractDownload PDF (3814K) -
Kiyoshi SEKIGAWA, Mamoru KOBIYAMA1992 Volume 42 Issue 1 Pages 16-20
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAtomic charges on each atom in RCOOH and RCOO- were obtaind by the calculation of 6-31 G ab initio molecular orbital method. The atomic charges of COO group, Q (COO), are in the order HCOOH>CH2=CHCOOH> McCOOH and the order is same of that of acid strength in the pKa values. The COO group attracts electrons from the H1 atom in the COOH group and a strong acid has the large effect. The atomic charge of H1 atom, Q (H1), is in the order HCOOH>CH2=CHCOOH_??_MeCOOH and Q (H1) indicates approximately the acid strength. The atomic charges on the C2 atoms in each aliphatic carboxylic acid have negative values and it suggests that those atoms are able to adsorb on the Al plane.View full abstractDownload PDF (3071K) -
Tadakazu OHNISHI1992 Volume 42 Issue 1 Pages 21-26
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSHydrogen embrittlement and SCC behavior of bending 7075-T6 aluminum alloy specimens were examined. The compression side of each specimen with both side notchs was only exposed to the cathodic charging solution or SCC environment. The notch strength was gradually decreased with increasing charging time. Prominent embrittlement was found on the tension side, but not on the compression side. Both the embrittlement and cracking on the tension side were also found in a SCC test specimen of which the compression side was only exposed. These results were only caused by the understood by the mechanism of hydrogen embrittlement hydrogen permeated from the compression side and transported to the tension side by diffusion. Thus, it was concluded that the hydrogen embrittlement was involved in the SCC mechanism.View full abstractDownload PDF (2981K) -
Yoshinobu SAKURAI, Yasuhiro FUKUSHIMA, Hiroyasu TEZUKA, Takeshi MURAKA ...1992 Volume 42 Issue 1 Pages 27-32
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe relation between microstructure and softening behavior was investigated in Al-8%Fe alloy extrudates which were produced through a roll quenching process. The extrudates were strengthened by dislocation structure introduced by hot extrusion at 703K. The dislocation structure remained stably even after exposure at 573K for 195h and the softening did not occure. At temperatures higher than 673K, both the transformation of metastable Al6Fe phase to stable Al3Fe phase and the recovery of dislocation structure occurred simultaneously. Hence, hardness of extrudates decreased with increasing of annealing time. At temperatures higher than 773K, softening occurred immediately but no remarkable grain growth was observable. This is explained by the pinning effect of dispersoids on grain boundary migration.View full abstractDownload PDF (2813K) -
Nobuo KOBAYASHI, Hiroyuki ICHINOSE1992 Volume 42 Issue 1 Pages 33-37
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSA study has been conducted on the rate of oxide film formation of 99.99 mass%-pure aluminum in a 3kg·m-3 ammonium tartrate aqueous solution kept at 298K. The aluminum samples were cold-rolled to 10-90% reductions in thickness and the residual stress as well as pole figures were measured by X-ray, and were then tested at cell voltages of 5, 20 and 50V. Irrespective of the cell voltages, the rate of film formation showed minima at 30 and 80% reductions, and a maximum at 50% reduction. Residual stress of the samples showed maxima at 30 and 80% reductions and a minimum at 50% reduction. The relation between the rate of oxide film formation and the residual stress was tentaively ascribed to the difference in physical density of the oxide film which formed at the first stage of the anodization. The texture, formed by cold-rolling, did not have any effect on the rate of the oxide film formation.View full abstractDownload PDF (2921K) -
Hee Teak SHIN, Makoto SUGAMATA, Junichi KANEKO1992 Volume 42 Issue 1 Pages 38-44
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSRapidly solidified flakes of six alloys systems (Al-Fe, Al-Mn, Al-Si-Fe, Al-Si-Mn, Al-Si-Fe-Mn and AC8A) were produced by using an apparatus combining atomization and water-cooled single copper roll. Consolidation of the flakes was done by cold pressing, degassing and hot extrusion. Metallography and mechanical properties were studied in order to evaluate the effect of 15mass%Si addition on properties of Al-Fe and Al-Mn base rapidly solidified P/M materials. Tensile strength of Al-Fe P/M materials at room temperature was increased by addition of 15%Si, whereas Al-Mn alloys with 15%Si addition showed almost same strength as those without 15%Si addition. However, elevated temperature tensile strength of the alloys containing 15%Si was lower than that of Al-Fe and Al-Mn binary alloys. P/M material of Al-15%Si-8%Fe alloy showed the highest tensile strength of about 410MPa at room temperature, and Al-8%Fe alloy showed the highest tensile strength of about 140MPa at 573K. Ductility of P/M materials was reduced by addition of 15%Si.View full abstractDownload PDF (3226K) -
Tetsuya TAKAAI, Yoshihiro NAKAYAMA1992 Volume 42 Issue 1 Pages 45-51
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSFatigue crack growth in 5083 aluminum alloy specimen was studied experimentally using compact tension specimens. Results are summarized as follows; (1) At a constant load amplitude, log-log plot of crack growth rate (da/dN) vs. stress intensity factor range (ΔKeff) becomes linear in the intermediate ΔK range. (2) Fatigue crack growth is retarded by the overloading and the crack growth rate is depressed with increase in the cycle numbers of overloading. (3) Crack growth rate depends on the number of overloading cycle in view of the crack opening ratio. (4) The overloading results in the closure of crack, the area of which increases with increase in the number of overloading cycle.View full abstractDownload PDF (4207K) -
Katsuaki SUGANUMA1992 Volume 42 Issue 1 Pages 52-59
Published: January 30, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (4174K)
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