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Volume 55, Issue 8
Displaying 1-6 of 6 articles from this issue
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RESEARCH REPORT
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Toshikatsu ASAHINA, Yosuke ITOH2005 Volume 55 Issue 8 Pages 337-342
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSPure titanium sheet of 0.6 mm in thickness was butt welded without after gas shield using a pulsed YAG laser welding machine. Effect of welding conditions on the pulsed YAG laser weldability was investigated concerning the bead appearance, mechanical properties and microstructures of welded joints. On the optimum welding conditions, the welded joints were free from welding defects and showed satisfactory bead appearance. Without after-gas-shield, color of the bead surface did not change. The microstructure of the fusion zone showed epitaxial growth of coarse columnar grains from the fusion boundary. Hardness in the fusion zone of the welded joints showed a higher value than that of the base metal. Regardless of the welding conditions, both tensile properties and bending properties of the joints showed almost the same tendency to those of the base metal. From the deep drowing test, the formability of butt welded sheet showed nearly equal to that of the base metal regardless of welding speed. As a result of this study, it became clear that YAG laser welded pure titanium thin sheet showed excellent formability.View full abstractDownload PDF (2243K) -
Hiroshi FUKUTOMI, Kyu-Seop PARK, Yasuhiro YAMAGUCHI, Kazuto OKAYASU2005 Volume 55 Issue 8 Pages 343-349
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSVarious processes consisting of high temperature deformation and heat treatment are experimentally examined on Ti-43mol%Al in order to control the lamellar arrangement in TiAl intermetallic compound. High temperature uniaxial compression in α+γ as well as α2+γ two phase state is effective to rotate the lamellar interface to the position parallel to the compression plane. The high temperature compression in α2+γ two phase state results in the formation of many cracks along the lamellar colony boundaries while no cracks are observed when the compression is made in the α+γ two phase state. Deformation in the two phase state deduce the formation of many single phase grains along the colony boundaries. It is found that the heat treatment at the temperature slightly higher than that for high temperature deformation in the α+γ two phase region is effective to eliminate the single phase grains. Compression creep tests are performed on two kinds of specimen having different lamellar arrangement; one has the lamellar interface parallel to the compression direction and the other has the interface inclined about 45° to the compression direction. The specimen having the lamellar interface parallel to the compression direction shows the creep rate much lower than that of the other.View full abstractDownload PDF (1286K) -
Shuhei OSAKI, Hideki KONDO, Katsuyuki KINOSHITA2005 Volume 55 Issue 8 Pages 350-356
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSEffect of Cr addition on properties of intergranular corrosion (IC) and stress corrosion cracking (SCC) in an acid sodium chloride (ISO) solution was evaluated by using four kinds of Al-Mg-Si alloys with a constant Mg content of 0.7mass% ; No. 5 (Al-Mg-1.1%Si), No. 7 (Al-Mg-0.44Si-0.34Cu), and alloys No. C5 and No. C7 with 0.2% Cr addition respectively. The excess Si alloys No. 5 and No. C5 showed little susceptibility to IC at any stage of aging at 443K, whereas the Cu containing alloys No. 7 and No. C7 exhibited some IC at the stage from underaging to peak-aging (for 28.8 ks at 448K). The alloy No. C7 however became immune to IC at the stage of overaging. Tensile tests by SSRT (slow strain rate technique) were carried out at strain rate 5.5×10-7/s to evaluate the index I of susceptibility to SCC as the ratio of reduction in elongation, compared to that in laboratory air. The index I of the peak-aged specimen was ranked on the order of alloy No. 5 (0.98)>No. 7 (0.72)>No. C7 (0.69)>No. C5 (0.23), which was in a good correspondence to the failure-time property obtained by a constant load SCC test. SSRT therefore should be useful as a rapid testing method to estimate SCC resistance. The Cr addition to the excess Si alloy resulted in a marked improvement of SCC resistance. The high resistance of alloy No. C5 were attributed to an increase in uniform corrosion due to a fine grain structure and distribution of dispersoids AlSi (Cr, Fe) or AlSiFe in grains.View full abstractDownload PDF (1945K) -
Yasuyuki TAKATANI, Rika TAMAI, Atsushi YAMAMOTO, Harushige TSUBAKINO2005 Volume 55 Issue 8 Pages 357-362
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSThe corrosion behavior of deposited magnesium film on AZ31 alloy, pure magnesium and AZ31 alloy were studied from the measurement of electrochemical impedance spectroscopy (EIS) in 0.5 mol/dm3 sodium chloride solution (pH 6.5) at 308K. The magnesium film on AZ31 alloy was prepared by evaporation process using 3N-Mg (99.9mass%Mg) material and the thickness of the film was 100 μm. The corrosion potentials of magnesium materials became negative value with decreasing these impurities contents. Corrosion resistance of magnesium materials measured by EIS increased with decreasing these impurities. It is found that the corrosion resistance and corrosion potential of deposited magnesium film correspond to that of 6N-Mg (99.9999mass%Mg).View full abstractDownload PDF (1456K)
REVIEW
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Toshihiko KUWABARA, Kengo YOSHIDA2005 Volume 55 Issue 8 Pages 363-370
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSDownload PDF (979K)
LECTURE
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Hisashi Hayashi2005 Volume 55 Issue 8 Pages 371-376
Published: August 30, 2005
Released on J-STAGE: June 30, 2021
JOURNAL FREE ACCESSDownload PDF (624K)
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