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Volume 58, Issue 5
Displaying 1-5 of 5 articles from this issue
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RESEARCH REPORT
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Hideo Sano, Takashi Ishikawa, Nobuki Yukawa, Yoshinori Yoshida, Takato ...Article type: Research Report
2008 Volume 58 Issue 5 Pages 183-188
Published: May 30, 2008
Released on J-STAGE: June 30, 2008
JOURNAL FREE ACCESSStudy on metal flow in extrusion billet is fundamental and useful to understand extrusion technology. In particular, knowing the behavior of skin of extrusion billet is indispensable to maintain qualities of extrusions. In order to investigate its behavior, extrusion experiments of clad billet and the FE analysis by DEFORM-2DTM were performed. The calculated behavior of billet skin was similar to that in experiment. It was considered that the results of FE analysis were acceptable to estimate the actual behavior of metal flow in extrusion. The billet skin penetrated the core in indirect extrusion and it was piled up at the back end of billet in direct extrusion. Slight dead metal zone appeared on the outer side of die face in indirect extrusion. Shear zone appeared between dead metal zone and flow zone in direct extrusion. Moreover, die semi-angle affected the behavior of billet skin in direct extrusion. 70 degree semi-angle die restrained billet skin from entering extruded product compared with 90 or 110 degree semi-angle die.View full abstractDownload PDF (2389K) -
Hideo Sano, Takashi Ishikawa, Nobuki Yukawa, Yoshinori Yoshida, Takato ...Article type: Research Report
2008 Volume 58 Issue 5 Pages 189-193
Published: May 30, 2008
Released on J-STAGE: June 30, 2008
JOURNAL FREE ACCESSStudy on metal flow in extrusion billet is fundamental and useful to understand extrusion technology. In particular, knowing the skin behavior of extrusion billet is indispensable to maintain qualities of extrusions. In order to investigate its behavior, the FE analysis by DEFORM-2DTM was performed. The billet skin was piled up at the back end of billet in direct extrusion. The skin behavior in single layer model analysis was similar to that of 2 layer model analysis. Therefore, single layer model analysis can investigate the skin behavior. Friction between billet back end and ram affected the behavior of billet skin. High lubricant accelerated thin skin 2.1% of billet diameter entering extrusion, but it constraint thick skin 6.4% of billet diameter entering extrusion.View full abstractDownload PDF (4271K) -
Atsushi Yamamoto, Yuichiro Tsukahara, Shinji FukumotoArticle type: Research Report
2008 Volume 58 Issue 5 Pages 194-198
Published: May 30, 2008
Released on J-STAGE: June 30, 2008
JOURNAL FREE ACCESSRandomization of cube texture formed in 6061 aluminum alloy was attempted by applying the wavy roll-forming method. Rolls having a wavy-shaped surface with waves which were about 8 mm in wavelength and 3 mm in amplitude were used for wavy roll-forming. Specimens were heated at 623 K and then roll-formed, followed by reheating at the same temperature and roll-formed again. This process was repeated 4 or 15 times, then the specimen was flattened using conventional flat rolls. The roll-formed specimens were annealed and then cold-rolled at room temperature and finally annealed at 773 K for 1.8 ks. Textures formed in the specimens were analyzed by electron backscattered diffraction measurements. The relative intensity of cube orientation was reduced by the annealing before the cold-rolling. The low intensity was maintained after the final annealing.View full abstractDownload PDF (13977K) -
Haruhiko Abe, Takahiko Nakamura, Shin-ya Komatsu, Masahiko Ikeda, Take ...Article type: Research Report
2008 Volume 58 Issue 5 Pages 199-204
Published: May 30, 2008
Released on J-STAGE: June 30, 2008
JOURNAL FREE ACCESSSpecimens of Al–1%Mg2Si–X%Cu alloys were isothermally heat treated at several temperatures between 573 K and 848 K for enough long periods. The resistivity in equilibrium state was estimated by extrapolation of t−1/3 plots at 573 K and 623 K, and at other higher temperatures by simply averaging measured values after long enough time. For comparison, the equilibrium resistivity was calculated for the each temperatures of heat treatment under assumptions that 0.02%Ti is always in solution and that Mg2Si, Cu and Fe would dissolve in Al up to equilibrium concentration in pseudo-binary or binary system. Though interactions between different species of solute atoms, except between Mg and Si, were completely neglected in above simple and rough assumption, the calculated resistivity coincided with experimental values within 0.5 nΩm. This is exactly same as previously observed resistivity fluctuation in present alloys quenched from 848 K, which was interpreted by the microsegregation during solidification. This coincidence suggests that amount of Cu mingling in Mg–Si or Al–Fe precipitates will be very small in the equilibrium state. If Cu bearing precipitates were observed, total amount of Cu in the precipitates will be too small to decrease the resistivity of solid solution. In another report on 473 K aging behavior of present alloys, it was suggested that solute Cu would enhance degree of supersaturation during the aging. However in the equilibrium state, the Cu addition up to 0.72% seems not to elevate so much the temperature of perfect dissolution of 1% Mg2Si.View full abstractDownload PDF (558K)
REVIEW
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Makoto HayashiArticle type: Review
2008 Volume 58 Issue 5 Pages 205-211
Published: May 30, 2008
Released on J-STAGE: July 30, 2008
JOURNAL FREE ACCESSDownload PDF (2079K)
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