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Volume 44, Issue 1
Displaying 1-12 of 12 articles from this issue
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Kenichi HIRANO1994 Volume 44 Issue 1 Pages 1-2
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (283K) -
Shigeru IWASAWA, Yuji NEGISHI, Shigeharu KAMADO, Yo KOJIMA, Ryuji NINO ...1994 Volume 44 Issue 1 Pages 3-8
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIn this study, compositional dependence of age hardening characteristics and high temperature tensile properties is investigated in binary magnesium alloys with 5, 10, 15 and 20 mass%Gd or Dy. Considerable age hardening is recognized in alloys with higher content of Gd or Dy. In case of equal rare earth metal contents, precipitates which play an important role for the age hardening of Mg-Gd alloys are more stable than those of Mg-Dy alloys at elevated temperatures. A Mg-20 mass%Gd alloy, therefore, exhibits remarkable age hardening even at 300°C. Tensile strength of Mg-Gd and Mg-Dy alloys increases linearly with Gd or Dy content and reaches the maximum tensile strength, 310 N/mm2 at 300°C for Mg-20 mass%Gd and 275 N/mm2 at 200°C for Mg-20 mass%Dy. The values are far superior to those of the conventional heat resistant magnesium and aluminum alloys. Elongation of Mg-Gd and Mg-Dy alloys decreases with increase in Gd or Dy content, and the elongation of Mg-20 mass%Gd and-20 mass%Dy alloys is less than 1% below 200°C, whereas the alloys containing 5 and 10 mass% shows higher elongation than 2% at room temperature.View full abstractDownload PDF (956K) -
Akira YUASA, Shinji MATSUI, Shigeharu KAMADO, Yo KOJIMA1994 Volume 44 Issue 1 Pages 9-15
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAn AZ91D magnesium alloy was reheated to the temperature of the semi-solid state and was pressure-cast by employing a die casting machine. The effects of casting conditions on structures, fluidity and mechanical properties were investigated. Fluidity is improved by using stir-cast materials and by increasing both the reheating temperature from 570°C to 580°C and the plunger speed from 0.6m/s to 1.1m/s. The improved fluidity results in the uniform flow of the solid and liquid and produces sound products without any macroscopic defects caused by the entrapping gas bubble. But low temperatures of the permanent mold and the temperature drop of the semi-solid materials in shot sleeve lead to form microscopic defects. Tensile strength of the specimen with good fluidity is 140-200N/mm2 and is higher than that of an as-stirred specimen, but is lower than that of a die-cast specimen.View full abstractDownload PDF (1466K) -
Hideyuki MIZUTANI, Hisakimi NOTOYA, Shigeru YAMADA, Akira TAKAYANAGI, ...1994 Volume 44 Issue 1 Pages 16-21
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIt is necessary to elucidate the relation between characteristics of work materials and cutting phenomena, in order to select a certain rational condition in cutting of aluminum alloys. In this study, an investigation on effects of characteristics of work materials on machinability was carried out by a simple model experiments. Various aluminum alloys were examined by sintered diamond tool and high speed steel SKH4A tool. The results may be summarized as follows: The cutting state is controlled by the built-up edge. In cutting without built-up edge, however, the mechanical properties of work material affect its cutting process, that is, the cutting forces are in proportion to hardness of work. The tangential force is strongly influenced by shear energy at chip formation. Cut surface roughness and depth of flow layer decrease with increase in hardness and decrease in elongation of work.View full abstractDownload PDF (790K) -
Toshio HAGA, Mitsugu MOTOMURA1994 Volume 44 Issue 1 Pages 22-27
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEffects of the polishing condition of the roll on the roll contacting surface of the foil manufactured by the single roll method were investigated. The surface of roll made of copper was polished by #240, 600, 1200 emery paper, in direction either parallel to rotating direction or to lateral direction. Three specimens, 99.99 mass%Al, Al-2 mass%Si and Al-12 mass%Si were examined at a roll speed of 1500rpm (24m/s)and 3500rpm (55m/s). The wetting pattern on the roll contacting side surface of the foil consists of the uncontacting area and directly contacting area with the roll. Triangle shaped depressions pointing the rotating direction are found on the uncontacting area. The polishing direction does not affect the direction of the depressions while small depressions are not observed in the case of the roll polished in the lateral direction. The roll should hence be polished in the lateral direction. The effects of the polishing condition and direction on the wetting pattern, on the roughness of the roll contacting surface of the foil, and on the contact area between foil and roll are not greater than those of the roll speed.View full abstractDownload PDF (951K) -
Mahmoud F. HAFIZ, Toshiro KOBAYASHI1994 Volume 44 Issue 1 Pages 28-34
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSInstrumented Charpy Impact Test has been used to evaluate the effect of strontium (Sr) level and solidification cooling rate on the impact toughness and its parameters (crack initiation and crack propagation energies) of high purity eutectic Al-Si alloy. In addition, tensile properties has been also investigated. It has been found that, both crack initiation and crack propagation energies are improved gradually with increasing Sr content with a consequent increase in the toughness. This confirms also the high strength and ductility displayed by modified alloy. The improvement amount not only depends on the Sr level but also on the cooling rate imposed during solidification. Fractographic study revealed that the crack is initiated in the eutectic phase by fracture of Si particles. This crack seems to propagate in a brittle fashion in a nonmodified alloy while it proceeds in a ductile manner in a modified one. Dimple pattern of fracture is found to be the characteristic of modified alloy. The higher ductility and toughness of modified alloy in addition to the change in the fracture characteristics can be attributed only to the fine fibrous morphology of Si particles achieved by modification and the stress-strain state in the matrix material associated with the fineness of Si particles.View full abstractDownload PDF (1387K) -
Masahiko IKEDA, Shin-ya KOMATSU, Takashi SUGIMOTO, Kiyoshi KAMEI1994 Volume 44 Issue 1 Pages 35-40
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEffect of Al addition on the isochronal aging of Ti-20 mass%V (Ti-20V) alloy was investigated by resistivity and hardness measurements, diffraction methods and structural observations. Ti-20V alloy shows two resistivity minima corresponding to precipitation of isothermal ω phase and that of α phase. The resistivity minimum due to ω phase precipitation gradually shifts to higher temperature with Al content and disappears in Ti-20V-8Al alloy. The Al addition above 8% causes the resistivity decrease due to only the α precipitation. These have been confirmed by the diffraction methods, and explained by suppression of ω and enhancement of α precipitation by Al addition. In the Ti-20V alloy, ω precipitation causes age-hardening, whereas α precipitation causes softening. Contrary to this, in Al added alloys, the contribution of α precipitation to hardness increases with Al content. TEM observation discloses 400nm long α plates in Ti-20V and fine, less than 30nm, α platelets, in Ti-20V-10Al alloys aged up to 773K.View full abstractDownload PDF (1281K) -
Norio TAKAKURA, Katsuhiko YAMAGUCHI1994 Volume 44 Issue 1 Pages 41-47
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSInterstage annealing is often employed as a method to increase the forming limit of sheet metals. This paper describes the effect of interstage annealing on the surface roughening and the improvement of limit strain of aluminum sheets. A rigid-plastic finite element simulation of plane strain tension was firstly made to predict how the limit strain could be increased by the interstage annealing and how the surface roughening would develop with plastic strain after the interstage annealing. Uniaxial tension, plane strain tension and hole expansion tests were then carried out to confirm the result of simulation. The simulation and experimental results show that the interstage annealing contributes to the recovery of ductility, but on the contrary, the increase in plastic strain due to the annealing causes the development of the surface roughening which induces a localized necking. As a result of these two effects which oppose each other, the total strain achieved is limited even if the number of interstage annealing is increased.View full abstractDownload PDF (856K) -
Yoshimasa TAKAYAMA1994 Volume 44 Issue 1 Pages 48-56
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
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Koichi ANZAI1994 Volume 44 Issue 1 Pages 57-66
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (1226K) -
Junichi KANEKO1994 Volume 44 Issue 1 Pages 67-68
Published: January 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (260K) -
1994 Volume 44 Issue 1 Pages va
Published: 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (108K)
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