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Volume 40, Issue 7
Displaying 1-13 of 13 articles from this issue
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Hiroshi TOKISUE, Kazuyoshi KATO1990 Volume 40 Issue 7 Pages 489-494
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSTurning machinability tests were performed on the magnesium alloy castings MC2 by measuring the cutting resistance, the cutting ratio, the shear angle, the surface roughness and the chip formation. Regardless of the side rake angle, both the tangential and the traversing force of the alloy were independent of the cutting speed, and were affected remarkably by increasing the feed. The tangential force decreased with increasing the side rake angle. The traversing force showed a negative value with acceleration of the feed using the side rake angle of 30°bit. Both the cutting ratio and the shear angle increased with acceleration of the cutting speed and the feed, and 0.54 to 0.82 as the cutting ratio and 30.2°to 44.6°as the shear angle. The machined surface finishing showed smoother with increasing the cutting speed and decreasing the feed, and was superior or nearly to that calculated theoretically. Both the large and small spiral coil type chips were easily treatable. There was no trouble in the flaming during cutting. The MC2 alloy had excellent machinability in the high speed heavy cutting.View full abstractDownload PDF (1222K) -
Yoshinari OKI, Yoshihiro YOSHIDA, Kazuo DOAI, Tomokazu YAMASHITA1990 Volume 40 Issue 7 Pages 495-500
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe skin of a 6063 aluminum alloy billet folds inward during the direct hot extrusion. To examine the metal flow, a 6063 billet was sliced along the meridian plane and grids were etched on this plane. The metal flow was measured at the beginning, middle and end of the extrusion process from distortions of the grids. To examine the metal flow at the back end of the billet, 4 bands were carved near the end of the billet and these bands were filled with 4043 aluminum alloy. The metal flow at the back end were measured similarly from distortions of 4 bands. Ater 4 different-length billets were extruded, the unextruded remainders were cut in half in order to observe the metal flow. These remainders were then covered with anodic oxide film in a H2SO4 bath and colored electrolytically in a Ni-salt bath. These experiments show that the skin near the back end of the billet folds into the billet during the compression of the first stage of the extrusion. The folded length of the skin near the back end of the billet is directly correlated to the ratio determined by the billet diameter and the container diameter. By decreasing the clearance between the container and the billet, this folded length can be decreased.View full abstractDownload PDF (3140K) -
Susumu IKENO, Kazuhiro KAWASHIMA, Kenji MATSUDA, Hiroshi ANADA, Shizuo ...1990 Volume 40 Issue 7 Pages 501-506
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEffects of aging treatment on Al-1%Mg2Si-alumina particles dispersed composite materials were investigated by the observation of analytical transmission electron microscope and electrical resistivity measurement. An ability of age hardening is remarkably decreased by addition of 4% alumina particles as compared with that of Al-1%Mg2Si alloy. When volume fraction of alumina particles is increased up to 20%, age hardenability is not obtained more. The lack of hardening in the matrices of the composite should be attributed to the decrease in β' precipitates. The spinels are observed at composite materials and they show often twin structure.View full abstractDownload PDF (3891K) -
Yasuhiro UETANI, Kenji MATSUDA, Shizuo TADA, Susumu IKENO1990 Volume 40 Issue 7 Pages 507-513
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSSlip bands formed after small additional deformation (Δε=0.5%), are observed as straight lines in the lower strain region and at that strain region the stress-strain curve can be approximated by the Ludwik equation. The measurements of slip band length have been made in this strain region for various grain sizes of aluminum and Al-5% Mg alloy. The slip band length decreases with strain. At constant strain, the larger the grain size is, the longer is the slip band length in both aluminum and Al-5%Mg alloy specimens. The linear relation between flow stress and inverse square root of grain size is not observed at higher strain region. On the other hand, linear relation between flow stress and inverse square root of slip band length can be seen at any strains. At constant grain size, linear relations are also observed with decreasing strain between flow stress and inverse square root of slip band length, and the slopes of those linear lines are almost the same, irrespectively of the grain size. Slip band length-strain curves calculated from the Ludwik equation are in good agreement with the experimental stress-strain curves.View full abstractDownload PDF (766K) -
Hajime KATO, Tatsumi TOZAWA, Yoshimasa TAKAYAMA1990 Volume 40 Issue 7 Pages 514-519
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAcoustic emission voltage versus strain curve showed a peak near yield point where the plastic deformation started. After showing the peak, the acoustic emission voltage reduced gradually with increment in the plastic strain. Fluctuations in the acoustic emission voltage also emerged after about 1.5% plastic strain. Both the value of acoustic emission peak voltage and the amplitude of fluctuations in the acoustic emission voltage became higher as the average grain size increased. The acoustic emission signals generated under the tensile deformation were mostly burst-type ones. Moreover, on the surface of deformed specimen, a lot of deformation twins were observed. Therefore, it was assumed that the burst-type signals resulted mainly from the formation of deformation twins.View full abstractDownload PDF (829K) -
Hee Teak SIN, Makoto SUGAMATA, Junichi KANEKO1990 Volume 40 Issue 7 Pages 520-526
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSRapidly solidified flakes of Al-2 to 8wt%Fe alloys were produced by atomizing the alloy melt and subsequent splat quenching onto a water-cooled copper roll. Mechanical alloying treatment (MA) was applied to the rapidly solidified flakes by using a high energy ball mill with addition of stearic acid as a process control agent. Consolidation of flakes or MA powders was done by cold pressing, degassing and hot extrusion. A significant hardness increment was observed by MA treatment. After consolidation, P/M materials from MA powder showed very fine dispersoids and fine subgrain structures. Isochronal annealing experiments revealed microstructural stability was high at temperature up to 400°C. The MA treatment was significantly effective in improving the mechanical properties of rapidly solidified P/M Al-Fe alloys. Tensile strength of a P/M Al-8%Fe alloy increased to about 67kgf/mm2 at room temperature and to 27kgf/mm2 at 300°C. These improvements are attributed to the introduction of fine oxide/carbide dispersoids and fine subgrain structures formed during MA. However, decrease of ductility was accompanied in the mechanically alloyed P/M materials.View full abstractDownload PDF (1588K) -
Hiroshi ASANUMA, Mitsuji HIROHASHI, Masahiko KASE, Takashi KIKUCHI1990 Volume 40 Issue 7 Pages 527-532
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSStainless steel fiber reinforced aluminum with using zinc to form the interface layer was fabricated, and bending of the composite as secondary forming was tried. That composite was fully strengthened at 643K which was just below eutectic temperature of Zn-Al alloy (655K). Over the eutectic temperature, the fiber-matrix interfacial stress τ of the composite was remarkably reduced. Taking advantage of loose state of the interface layer, bending of the composite became possible without fiber breakage and buckling which was impossible in the case of the composite at lower temperatures or without the interface layer. The once remarkably reduced τ could be increased by mutual diffusion between the interface layer and the matrix caused by heat treatment, and the composite was fully strengthened even at 673K which was beyond the eutectic temperature. Accordingly, the possibility of realizing long fiber reinforced metal which could be secondarily formed was clarified.View full abstractDownload PDF (2505K) -
Yoshinari OKI, Yoshihiro YOSHIDA, Masao INOUE, Tomokazu YAMASHITA1990 Volume 40 Issue 7 Pages 533-537
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIn order to understand the temperature distribution in a billet at the induction heating stage of extrusion process, a computer analysis program is developed and some results of its application are presented in this work. Three coils were linearly arranged, and two billets were inserted into the coils one after another, and then were heated up to the pre-determined temperature in two steps, that is, pre-heating step and main heating step. Repeated numerical calculation were carried out, considering Joule heat due to induced current, heat conduction and radiation from surface of the billet. The temperature distribution in the billet at pre-heating step, main heating step and just before insertion into the container were given on an isothermal map. The computer analysis on 155, 204, 254 and 307mm diameter billets showed that the thicker billet had the more uneven radially temperature distribution, and that at the warming-up stage of induction heater for the thicker billet each main heating time was unstabler, and the poorer temperature distribution was obtained.View full abstractDownload PDF (520K) -
Takeshi MURAKAMI, Mikio YAMAMOTO, Akihiko KAMIO, Tsuneo TAKAHASHI1990 Volume 40 Issue 7 Pages 538-542
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAge softening phenomena were investigated on aluminum alloys 5182 and 5052 which were heavily rolled and then aged at room temperature. Tensile strength and proof stress decrease but elongation increases with increase in the aging time. Elongation is larger in the transverse direction than in the rolling direction either after the rolling or in the aged condition. The ductility showed an anisotropy which is correlated with the tendency of serrated flow and Lüders band formation.View full abstractDownload PDF (1853K) -
Masahiro JONO, Atsushi SUGETA1990 Volume 40 Issue 7 Pages 543-553
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (3018K) -
Hideki IMAMURA, Kenji HIGASHI1990 Volume 40 Issue 7 Pages 554-555
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (286K) -
Masami ASANO1990 Volume 40 Issue 7 Pages 556-569
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (1653K) -
Hiroaki YOKOBAYASHI1990 Volume 40 Issue 7 Pages 570-571
Published: July 30, 1990
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (255K)
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