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Volume 55, Issue 7
Displaying 1-5 of 5 articles from this issue
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RESEARCH REPORT
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Takeshi NISHIWAKI, Naoyuki KANETAKE2005 Volume 55 Issue 7 Pages 306-309
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSThe deep drawability of the peripherally softened aluminum alloy blanks was investigated for various punch shapes. The flange parts of the 6061-T6 sheets were locally solution treated and softened using various heated dies. Deep drawing tests of the blanks were examined using a flat and a hemispherical cylinder punches. The limit drawing ratios (LDR) of local solution treated blanks were larger than those of the homogeneous T6 blank for both flat and hemispherical punches. The optimal softened region for a hemispherical punch was larger than that for a flat one. The LDR and the optimal softened region of local solution treated blanks were predictable by the FEM analysis for both hemispherical and flat punches. The optimal softened region of calculations for a hemispherical punch became larger with increasing n value of a central hard part.View full abstractDownload PDF (505K) -
Nobuya SHINOZAKI, Jun MORITA, Kyoko WASAI2005 Volume 55 Issue 7 Pages 310-314
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSThe contact angle between molten magnesium and graphite was measured at 973K in order to obtain basic data for magnesium-base composite manufacturing. Two kinds of sessile drop methods were used for the purpose: the conventional method in which solid magnesium was put on graphite prior to heating and another method in which molten magnesium was dropped on graphite by a metal dropping device. In the conventional sessile drop method, though it was difficult to melt magnesium due to the surface oxidation, pure magnesium droplet could be finally gotten after trial and error. It was possible to easily get pure magnesium droplet in the sessile drop method using a dropping device, and magnesium evaporated rapidly. The contact angle between molten magnesium and graphite was estimated to be about 125 deg from the results obtained by the two methods. It was guessed that molten magnesium and graphite were bonded at the interface by the weak intermolecular force, because the work of adhesion was calculated to be 7 kJ/mol.View full abstractDownload PDF (652K) -
Shinichi NISHIDA, Mitsugu MOTOMURA2005 Volume 55 Issue 7 Pages 315-320
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSMagnesium is the lightest structural material, so that it will be possessed to diffuse in future. But its formability, which is poor at room temperature, is an obstacle. Continuous strip casting process is well suited to make strip of such materials. In this study, we made an attempt to apply the melt drag process, which is kind of single roll continuous strip casting process, for production of pure magnesium and magnesium alloy AZ31 strip. Melt magnesium is very activated, and we designed experimental apparatus for melt magnesium. Fine strip of pure magnesium was cast in the range of roll speed: 5∼20 m/min, and the strip thickness was 1.4∼2.4 mm. AZ31 fine strip was cast in the range of 5∼30 m/min, the strip thickness was 0.6∼1.6 mm. Roll speed much affected the strip thickness in low roll speed. And the thinner strip thickness is, the more refining grain size is.View full abstractDownload PDF (950K) -
Tadashi HAITANI, Yosuke TAMURA, Norio KONO2005 Volume 55 Issue 7 Pages 321-326
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSWe conducted this study to clarify the relationship between manganese solubility and grain sizes of Mg-Al alloys. Mg-5%Al, Mg-9%Al, and Mg-11%Al alloys were prepared using high-purity magnesium (>99.99%) and aluminum (99.99%). These alloys were melted at 1123K by adding electrolytic manganese (99.99%) and solidified as alloy ingots after continuous stirring for 21.6ks. The alloy ingots were then remelted at 933K, 998K and 1073K, and held statically at each of these temperatures for 21.6ks. By this process, the excess Mn that existed over its liquid solubility precipitated and sedimented to the bottom of the melt. Thus, the solubility of Mn in liquid Mg-Al alloys was determined by analyzing the upper surface of the ingots quenched from each holding temperature. Consequently, the following equations were derived as experimental formula for determining solubility of Mn in liquid Mg-Al alloys at different temperatures: Y = 1.79-6.22×10-2X (1073K), Y = 1.28-4.41×10-2X (998K), and Y = 0.90-3.35×10-2X (933K), where X is the concentration of Al (mass%) and Y is solubility of Mn (mass%). Mg-9%Al alloys containing 0 to 3% Mn were prepared in order to investigate the influence of Mn on grain sizes, and microscopic observations of these alloys were carried out with and without superheating of the specimens. The grain diameter of high-purity Mg-9%Al alloys (0% Mn) is approximately 40 μm, which is finer than that of the commercial AZ91E magnesium alloy with superheating. Therefore, high-purity Mg-9%Al alloys have an essentially fine-grained structure. An increase in the Mn content tended to coarsen the grain structure of Mg-9%Al alloys that contain 0.02 to 2.27% Mn; however, the coarse-grained structure can be refined by superheating. Superheating plays a role in resetting the coarse-grained structure to a high-purity structure (initially fine-grained) when Mn is added. Further, it is clarified that the solubility of Mn in liquid Mg-Al alloys exhibits no relationship with either the grain size or the superheating effect.View full abstractDownload PDF (1475K)
REVIEW
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Makoto KOBASHI2005 Volume 55 Issue 7 Pages 327-332
Published: 2005
Released on J-STAGE: February 24, 2006
JOURNAL FREE ACCESSDownload PDF (1300K)
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