All issues
Volume 49, Issue 5
Displaying 1-5 of 5 articles from this issue
- |<
- <
- 1
- >
- >|
RESEARCH REPORT
-
Susumu ARAKAWA, Tomei HATAYAMA, Kazuhiro MATSUGI, Osamu YANAGISAWA1999 Volume 49 Issue 5 Pages 193-198
Published: 1999
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe alloying process and mechanical properties of Al–4mass%Cu/Al2O3 (0–5 vol%) composite powders produced by mechanical alloying method (MA) were investigated by scanning electron microscopy, X-ray diffraction and Vickers microhardness tests. The particle size of MA powders increased at early stage (welding predominant stage), then decreased (fracturing predominant stage) by repeating of welding and fracturing, and finally the MA powders became the fine eqiaxed powder particles (steady state). Dispersed Al2O3 particles in the MA powder made the eqiaxed powder particles fine. The hardness of Al–4 mass%Cu and Al–4 mass%Cu/Al2O3 MA powders steeply increased due to the work hardening at the initial stage of milling. The hardness of Al–4 mass%Cu powders was saturated with a certain value, while Al–4 mass%Cu/Al2O3 powders gradually increased. The gradual increase in hardness was caused by the homogeneous dispersion of Al2O3 particles into powder matrix. The addition of Al2O3 powders remarkably refined the MA powder particle size, and accelerated alloying, where a lattice parameter decreased with milling time and the formation of supersaturated solid solution proceeded. It has been considered that the Al2O3 particles in the MA powder activated the repeating process of the welding and fracturing during MA, which increased Al/Cu interfaces and the alloying is accelerated.View full abstractDownload PDF (1098K) -
Takashi NINOMIYA, Hirohito HIRA, Takao CHOH, Naoyuki KANETAKE1999 Volume 49 Issue 5 Pages 199-203
Published: 1999
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe forming test was performed at 773 K using a 250 mm × 250 mm blank sheet by the gas pressure, which was preset to achieve the average strain rate of 0.1/s. The rectanglar part is successfully formed with in about 10 seconds and the maximum thickness reduction strain is over 100% at the corner of the part. The high forming rate leads to the uniform thickness distributions of the formed part and it coincides with the bulge forming test conducted by authors in the previous work. From the results of measuring the change in contour shape and thickness distributions, the forming process is proved as follows. The sheet is bulged freely in the die at first and then attaches the bottom or side wall, finally formed along the corner of the die. The process coincides with the shape predicted in the calculation of the gas pressure pattern.View full abstractDownload PDF (944K) -
Masatsugu MAEJIMA, Matsufumi TAKAYA, Koichi SARUWATARI, Masanori HIRAT ...1999 Volume 49 Issue 5 Pages 204-208
Published: 1999
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSHard anodized coatings of aluminum have performed their parts most effectively in the fields for instance automobiles, precision machines, textile machines or sports, leisure industries. But in order to correspond to the propulsion of omission and available use of energy, hard anodized coatings will be demanded hardness and wear resistance further. On the background we have developed on aluminum anodized coating with excellent hardness and wear resistance. This coating is made by cathode electrolytic process in 0.1 N KMnO4 aqueous solution before anodizing in sulfuric acid solution. The layer made by cathode electrolytic process is constituted of complex oxide with Mn, Al and O elements. We think that the chemical solution of porous anodic oxide film in sulfuric solution is controlled with existence of this complex oxide on porous layer of anodized coating. The results of this research will settle surely that it is very difficult to anodize for some aluminum alloy castings and aluminum alloys die castings with low coating ratio on anodized coating.View full abstractDownload PDF (748K) -
Mitsuaki FURUI, Michiyo NOGUCHI, Shigeoki SAJI1999 Volume 49 Issue 5 Pages 209-213
Published: 1999
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSGrain refinement of aluminum alloys can be achieved by introducing a large amount of lattice distortions during an intense plastic deformation. In order to introduce high plastic strain to 3004 and 5083 aluminum alloys and to restrain a dynamic recovery, a two-directional rolling method at cryogenic temperature was applied. Superiority of the two-directional rolling method was verified by a stored energy obtained from differential scanning calorimetry (DSC) analysis, by a microstructure and by a work hardening. The stored energy and work hardening given by the two-directional rolling at cryogenic temperature to 50% reduction of area were larger than those given by the other types of rolling with same reduction such as two-directional rolling at room temperature, one-directional rolling at cryogenic temperature and one-directional rolling at room temperature. A recrystallized grain size at peak temperature of remarkable exothermal reaction was smallest in the two-directional rolling at cryogenic temperature compared with in the other rolling conditions. The recrystallized grain size at the peak temperature of the exothermal reaction was decreased with increasing the stored energy. The work hardening on ST–LT cross-sectional plane of these alloys strained by the two-directional rolling at cryogenic temperature was distributed more uniformly compared with that of these alloys strained by the other rolling.View full abstractDownload PDF (1392K)
REVIEW
-
Akihisa INOUE, Hisamichi KIMURA1999 Volume 49 Issue 5 Pages 214-221
Published: 1999
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDownload PDF (1583K)
- |<
- <
- 1
- >
- >|