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Volume 52, Issue 7
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
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Hiromi NAGAUMI, Kiyomi TSUCHIYA2002 Volume 52 Issue 7 Pages 293-297
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe effect of Mg content on porosity in Al–Mg alloy DC slabs was investigated. In this investigation, we performed an experimental study of the amount of porosity on laboratory scale (250 mm by 400 mm cross-section) DC slabs of Al–2, 3, 4, 5and 6 mass% Mg. We clarified the relationship between porosity formation and Mg contents of the DC slab quantitatively by measuring porosity size, fractions, and number of porosity from the surface to the center of slab. The following conclusions were obtained, (1) As the Mg contents increase the initial hydrogen contents increase, and the hydrogen contents can be expressed in a quadratic of Mg contents (mass%) with good accuracy. (2) When the Mg content is less than 2 mass%, the porosity were very small and distributed uniformly from the surface to the center of the slab. (3) When the Mg content exceeds 3 mass%, the pore sizes and the fractions increase from the surface to the center of the slab. As the Mg content increases the porosity content and number increase.View full abstractDownload PDF (379K) -
Osamu HASEGAWA, Ken-ichi MANABE, Hisashi NISHIMURA2002 Volume 52 Issue 7 Pages 298-302
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSPress bendability and deformation behavior at room temperature of AZ31 magnesium alloy were studied. AZ31 tube has a good bendability, because it does not tend to occur such undesirable deformations as wrinkling, collapse and cracking. Moreover, flattening of the tube is restricted with the internal mandrel. It became clear from the results of curvature distribution that AZ31 tube is conformed well to punch shape. Bending behavior, strain path and variation of thickness in press bending of AZ31 tube were investigated in addition to the examination of mechanical properties, strain path and variation of thickness in compression. The work-hardening characteristic of compression side of AZ31 tube is greatly different from that of the tension side. Based on the experimental results, we discussed on the deformation behavior and the reason of high buckling limit in bending of AZ31 tube in comparison with various 6063 aluminum alloy tubes.View full abstractDownload PDF (480K) -
Hitoshi YAE, Ryosuke KIMURA, Makoto YOSIDA, Gen SASAKI, Jin PAN, Koich ...2002 Volume 52 Issue 7 Pages 303-307
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSIn usual, the water-soluble lubricants are used in die-casting. But this system has fatal defect, namely, high-energy consumption and environmental problems. Recently, closed die system with use of powder lubricants is widely noticed. The effects of the contents of powder lubricant and die temperature on the quality of casting surface were investigated. The castings had a good correlation between surface glossiness and surface appearance according to the experts in the field of die cast, so surface glossiness was measured as one of the most important surface quality. The quality of casting surface was improved by decreasing the wax content in powder lubricants, because decreasing the wax content improved the glossiness, the flow line, and metal wave, and decreased the surface roughness. A high temperature of die improved the surface glossiness and roughness, because the fluidity was improved. Powder lubricants could provide a surface quality of castings better than conventional water-soluble lubricants.View full abstractDownload PDF (540K) -
Makoto MIYAZAKI, Hideaki NEGISHI2002 Volume 52 Issue 7 Pages 308-312
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSBuckling, impact resistance and energy absorption of dynamic axial compressed aluminum square tube are discussed. Numerical analysis of the deformation of the square tube is made by a finite element method. The result shows that ripples of buckling are produced in the surfaces of the tube wall when the striking mass reaches a certain values. The wave pattern on the deformed tube wall of 1 mm thick is concave-convex pattern in adjoining surface, while that of 2 mm thick is convex pattern in all surfaces. Absorbed energy of the deformed tube increases in proportion to axial displacement of the tube. Experimental results agree approximately with those of the finite element method analysis.View full abstractDownload PDF (406K) -
Makoto MIYAZAKI, Hideaki NEGISHI2002 Volume 52 Issue 7 Pages 313-317
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSAluminum square tube with a geometrical initial imperfection, i.e. a small distortion or hole on the tube wall before deformation is prepared in dynamic deformation test. Location and shape of the buckling deformation of the tube depend on the size and location of initial imperfection. Experimental results agree approximately with those of the finite element method analysis.View full abstractDownload PDF (397K) -
Xuyue YANG, Hiromi MIURA, Taku SAKAI2002 Volume 52 Issue 7 Pages 318-323
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSFine grain evolution taking place during deformation of magnesium alloy AZ31 was studied in compression at 673 K (0.73 Tm) and by using optical and SEM/EBSD microscopy. The flow curve shows a rapid hardening and a stress peak at relatively low strain (εp = 0.12), followed by a strain softening and then a steady state flow at high strains. Fine grains are evolved at serrated grain boundaries at around εp and developed rapidly during strain softening, finally leading to a roughly full evolution of equiaxial fine grains. On the other hand, kink bands are evolved at serrated grain boundaries and also frequently in grain interiors even at around εp. The misorientation of the boundaries of kink band increases rapidly during strain softening and approach a saturation value at high strains. The average size of the regions fragmented by kink band is almost the same as that of fine grains evolved in high strain. It is concluded therefore that new grain evolution can be controlled by a deformation-induced continuous reaction, i.e. continuous dynamic recrystallization (DRX), although many characteristics of new grain evolution process and its relation to flow behaviors are apparently similar to those in conventional, i.e. discontinuous, DRX.View full abstractDownload PDF (576K) -
Keizo SAKURAI2002 Volume 52 Issue 7 Pages 324-329
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSIn order to enhance drilling efficiency, a conventional machine tool and conventional drills are used in the drilling of aluminum alloys A2017–T3 and A6061–T6 with TiN coated SKH56 drills at high feed rates of 0.5 mm/rev and 1.0 mm/rev and the following cutting variables, cutting forces, drill life, drill wear, chip shape, burr shape, heat generation, and chip temperature are examined. Results show that satisfactory results in tool strength, drill life, and wear can also be obtained even with conventional drills at high feed rates. Besides, heat generation during high-feed drilling is lower than in normal drilling as made evident by the high chip disposal rate due to the dissipation effect of cutting temperature. It is clear from the results that high-feed drilling is possible with conventional drills.View full abstractDownload PDF (475K)
REVIEW
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Equo KOBAYASHI2002 Volume 52 Issue 7 Pages 330-334
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDownload PDF (378K)
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