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Volume 33, Issue 12
Displaying 1-8 of 8 articles from this issue
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Umewo HONMA1983 Volume 33 Issue 12 Pages 703-704
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (241K) -
Shigeo OYA, Takahiko FUJII, Fusanari KATO, Mitsuhiro OHTAKI1983 Volume 33 Issue 12 Pages 705-711
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSHot tearing tendency of binary Al-033% Cu and Al-013% Si alloys was studied by the new hindered hot tearing test, "I-beam test". Insulator (0.5mm in thickness) was pasted on the middle of the mold wall, in order to locate tears only in the middle of the test bars.
Hot tearing tendency of Al-Cu alloys was most increased at 12% Cu, and as the Cu content increased up to 15% Cu, hot tearing tendency was decreased. The healig phenomenon was visible in Al-2033% Cu alloys. In binary Al-Si alloys, hot tearing tendency was most increased at about 0.5% Si. As the Si content increased up to 4% Si, hot tearing tendency was decreased, and in Al-913% Si alloys, the healing phenomenon was visible.
Hot tearing was occured by "I-beam test" in the alloys it had not been recognized before by the previous test. So it is thought that hot tearing is the universal phenomenon in the solidification process. These hot tearing tendency was not explained by the temperature range of the semi-solid region.View full abstractDownload PDF (1693K) -
Shunsuke FUJIKI, Makoto TSUKUDA, Susumu KOIKE, Izumi FUKUI1983 Volume 33 Issue 12 Pages 712-717
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAl-7%Si-0.3%Mg and Al-7%Si-0.7%Mg alloy castings were solution heat treated at 535°C for 9h, preaged at 25°C, 75° and 125°C for different times up to 100h and finally aged at 180°C for 5h. Mechanical testing, electrical resistivity measurement and transmission electron microscopy were made. If the alloys are preaged at 25°C, the hardness, tensile and yield strengths lower. If preaged at 75° and 125°C, the alloys have mechanical properties identical to those of the alloys not preaged. The positive effect of two-step aging encountered in Al-Mg2Si alloys is never found in these casting alloys. These facts are attributed to the structure and excess silicon of the alloys.View full abstractDownload PDF (1313K) -
Koichi OHORI, Hideo WATANABE, Yo TAKEUCHI1983 Volume 33 Issue 12 Pages 718-728
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSSome Al-Mg-Si commercial alloys were extruded at various temperatures and rates. Mechanical properties, optical and electron microstructures, and textures of the as extruded and T6 tempered rods were investigated.
The press effect was observed in the T6 tempered rods extruded above about 450°C and the rods exhibited about 10kg/mm2 higher yield and tensile strength than those of rods free from fibrous structures.
The critical extrusion conditions which produce the press effect depend on the magnitude of recrystallization retarding effect of dispersoids and can be understood qualitatively in terms of a critical stored energy.
The press effect may be resulted from two effects; the subgrain hardening effect and the <111> texture strengthening effect retained completely after solution heat treatment. The former contribution seems to be as large as that of the latter.View full abstractDownload PDF (3050K) -
Hisashi SUZUKI, Motohiro KANNO, Hiroshi SAITOH1983 Volume 33 Issue 12 Pages 729-732
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe reason why the region free from η phase appeared in recrystallized regions was studied for an Al-6.0%Zn-2.3%Mg-1.2%Cu-0.18%Zr alloy subjected to slow cooling after solution-treatment. The cast alloy was homogenized, cold-rolled, solution-treated at 470°C and then step-quenched. It was found that the region free from η phase corresponded well to the region free from Al3Zr precipitate. It was also found that Al3Zr precipitate did not form, during homogenization of cast alloy, at interdendritic regions. This meant that zirconium concentration was extremely low at interdendritic regions, suggesting that zirconium contained Al-Zn-Mg-Cu alloy was peritectic-reaction type, like Al-Zr binary alloy.View full abstractDownload PDF (1649K) -
T.A. El-Bassyouni, A.A. Badr, A.N. Abdel-Azim, J. Lakner, Z. Olah1983 Volume 33 Issue 12 Pages 733-741
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSMolten commercial aluminium was oast in sand mould in the presence of high electric current. Grain refinement was enhanced as the current was increased. In case of alternating external magnetic field, however, there was no proportionality between the refinement and magnetic field strength. The ingot acquired fine equiaxed grains when the magnetic field was about 0.3 kilo gauss. At all other values, ingots showed mixed structure of equiaxed and columnar areas to varying proportions. The ingot cast in this experiment was about 100g.
The behaviour of the 4-kg ingot cast in an experimental semi-continuous casting machine was almost the same. The number of grains/cm2 in both experiments was about 700.View full abstractDownload PDF (2494K) -
Satoshi HASHIMOTO, Kojiro F. KOBAYASHI, Sei MIURA1983 Volume 33 Issue 12 Pages 742-748
Published: December 30, 1983
Released on J-STAGE: November 05, 2008
JOURNAL FREE ACCESSIn order to clarify roles of geometric factors to the heterogeneous nucleation of the aluminum by the primary Al3Ti, the crystallographic orientation relationships reported in the literature and characteristic features of the interface structures have been investigated. The orientation relations can be classified into two types, which consist of the semi-coherent and the so-called pseudo (near)-coincidence interface with low ∑ values. It becomes to be evident that the several orientation relations with higher probabilities of occurrence, for which the usual misfit definition shows high disregistry values, can be successfully explained by the interphase-CSL model. An originally proposed fully geometrical parameter to describe the lattice coherency, which is essentially ascribed to the concept of "lattice invariant" so as to conquer short-comings of the usual misfit definitions, satisfactorily predicts the experimentally measured preference among the various orientation relations. Consequently, we mensioned that the heterogeneous nucleation mechanism in the present system is to be under the strong control of the lattice coherency at the overgrowth/catalyst interface.View full abstractDownload PDF (1562K) -
Yujiro YOSHIDA, Mikio SASAJIMA1983 Volume 33 Issue 12 Pages 749-778
Published: December 30, 1983
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (3615K)
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