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Volume 42, Issue 2
Displaying 1-11 of 11 articles from this issue
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Kouzou KANAYAMA, Kouzi YOSHIOKA, Ichinori SHIGEMATSU, Yukio HIRAI1992 Volume 42 Issue 2 Pages 61-66
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIn order to reduce required thrust in tube reducing, a planetary ball die (PBD) which consisted of retainer and steel balls was developed. The required thrust was reduced to less than 60% of that for ordinary conical die. However, those value were in excess because effect of friction on the required force was neglected in analysis. To evaluate the required force exactly, analysis based on the energy method had been carried out considering the frictional energy. The thrust and torque obtained from that analysis agreed well with the experimental results. The increasing of the coefficient of friction led to remarkable increasing of thrust and few increasing of torque. When the value of reduction rate and/or of the feeding speed increased, the thrust and torque increased. The thrust and torque increased with the decreasing in ball diameter.View full abstractDownload PDF (2769K) -
Makoto INOUE, Kazuo MATSUZAWA, Osamu TANNO, Kiyoaki OHUCHI, Yo KOJIMA1992 Volume 42 Issue 2 Pages 67-73
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSHigh temperature tensile properties of Mg-8 and 13 mass%Li alloys containing Al, Cu, Zn or Ag have been investigated. Ultimate tensile strength and 0.2% proof stress decreased with increase in test temperature. Elongation of Mg-8%Li alloy was higher than that of Mg-13%Li alloy, while the ternary alloys were more ductile than the binary alloys. Mg-8%Li-1%Zn alloys annealed at 443K showed superplastic strain up to about 840% at the test temperature of 573K. Annealing in the recovery temperature range was effective for the development of superplasticity.View full abstractDownload PDF (3446K) -
Tetsuichi MOTEGI1992 Volume 42 Issue 2 Pages 74-77
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe influences of superheating, cooling rate, repetitive melting and solidification cycles, and addition of some types of oxides on the undercooling of zone refined aluminum were studied. A 20 grams sample of molten aluminum was first passed through a graphite filter in order to remove oxide films from the sample and then remelted and solidified in an extra high grade graphite crucible under vacuum conditions. The larger the degree of superheating of the sample, the larger is the degree of undercooling. The maximum degree of undercooling is 82K. When the sample is superheated by 300K above the melting point, no undercooling occurrs. Larger undercooling is obtained through air-cooling than through furnace-cooling. Further, while the addition of SiO2 powders eliminates undercooling in the sample, the addition of Al2O3 powders does not affect the degree of undercooling.View full abstractDownload PDF (2458K) -
Shinji TERUTA, Masafumi MIZOUCHI, Yotaro MURAKAMI1992 Volume 42 Issue 2 Pages 78-84
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAging behavior of solution-treated and cold-rolled Al-4.5%Mg, Al-4.5%Mg-0.35%Mn and Al-1.3%Mg-1.1%Mn alloy sheets containing 0.2%Cu was investigated by tensile test and electron microscopy. The alloy samples were isochronally aged at temperatures between room temperature and 300°C for 20s or isothermally aged at 220°C for 5 to 18000s. The decrease in the mechanical strength at higher temperatures than 260°C or at prolonged aging time longer than 1200s is suppressed by reducing the amount of Mn addition and increasing homogenization temperature as well as solidification rate during casting. The increased volume fraction of fine Mn-baded dispersoids is found to have the effect to decrease the mechanical strength during aging. The heterogeneous precipitation of the S phase (Al2CuMg) on the fine Mn-based dispersoide is found to occur in the solution-treated and then cold-rolled Al-1.3%Mg-1.1%Mn-0.45%Cu alloy sheet aged at 240°C for 2h.View full abstractDownload PDF (4735K) -
Yoshinobu MOTOHASHI, Hiroaki KIKUCHI1992 Volume 42 Issue 2 Pages 85-91
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe Al-Zn eutectoid-base superplastic alloy with a fine and granular microstructure has a weakness in mechanical strength such as creep resistance in a service environment. In order to improve the weakness, the alloy was continuously cooled with various cooling-rates from an α' solid solution temperature (648K) by means of a forced air-cooling technique. Then the relation between various microstructures produced by the eutectoid decomposition upon cooling and mechanical properties was studied. Within a cooling-rate range in which all or most of the microstructures become lamellar, the hardness of the alloy was expressed by an empirical equation. Contour lines of the hardness calculated from the equation agreed fairly well with the experimental datum points. A condition under which the produced microstructure was almost lamellar and the hardness showed the maximum was found to be the most suitable condition for improving the strength, aging stability and creep resistance of the alloy.View full abstractDownload PDF (4159K) -
Haruyuki NAKANISHI, Yoshiki TSUNEKAWA, Masahiro OKUMIYA, Masatake HIGA ...1992 Volume 42 Issue 2 Pages 92-97
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSWettability of ceramic reinforcements with molten metals plays a vital role in the quality of metal matrix composites (MMCs) fabricated through liquid processing: the poor wettability causes non-infiltrated defects to remain in pressure cast MMCs with a low applied pressure. Threshold pressure for infiltration is one of the promising methods to evaluate wettability, since the reinforcement itself in MMCs can be utilized in this method. The mica-ceramic particles which had been classified into three sizes (L, M, S) were supplied to measure the threshold pressure for molten aluminum infiltration. Pressure infiltrations to the particle preforms were performed at 998K in vacuum or air atmosphere. The threshold pressures for molten aluminum infiltration were found to be 80.9 (L), 77.8 (M) and 159kPa (S) in vacuum, and 96.9 (L), 96.1 (M) and 162kPa (S) in air atmosphere. The lower threshold pressures in vacuum can be ascribed to the better wettability. Non-infiltrated defects with a meniscus configuration were observed in the vicinity of a contact point of two particles. However, flat defects appeared between quasi-tangential planes in MMCs using L-size particle preforms, and aggregate defects were observed in S-size preforms. Modelling the defect with a meniscus configuration to estimate the defect size, the relation between the threshold pressure and the wettability can be derived from the work done by an applied pressure balancing the interfacial energy changes. The contact angle of mica-ceramics with molten aluminum in vacuum is calculated to be approximately 2.39rad which is obtained from the threshold pressure into the M-size particle preforms with less flat or aggregate defects. Hence, the relation between the threshold pressure and the contact angle depends on a configuration of non-infiltrated defects.View full abstractDownload PDF (3800K) -
Hajime IKUNO, Shin-ichi TOWATA, Fusayoshi MIURA, Ken-ichi SUZUKI, Sen- ...1992 Volume 42 Issue 2 Pages 98-104
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSCarbon fiber reinforced aluminum alloys (CFRM) are reported to have poor corrosion resistance because of galvanic corrosion, unstable carbide (ex. Al4C3) and stress corrosion cracking due to thermal residual stress of the matrix. In conventional composites made by the squeeze casting process, many fiber-to-fiber contacts are observed. At these fiber-to-fiber contact points of the CFRM, poor wettability between the carbon fiber and the aluminum alloy matrix forms meniscus defects. The effect of these meniscus defects on the corrosion resistance has not yet been clarified. In this paper, the corrosion resistance of hybrid FRM using carbon fibers with particulates and whiskers is investigated. The results obtained are as follows. CFRM with few meniscus defects and little Al4C3 indicated excellent corrosion resistance. CFRM with many meniscus defects indicated a much higher corrosion rate along the carbon fibers. These results suggest that the corrosion resistance of CFRM which indicates galvanic corrosion is considerably influenced by meniscus defects and Al4C3.View full abstractDownload PDF (4118K) -
Takashi ISHIKAWA1992 Volume 42 Issue 2 Pages 105-111
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (3931K) -
Hiroshi OKADA, Goroh ITOH, Motohiro KANNO1992 Volume 42 Issue 2 Pages 112-120
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (6464K) -
Toyoji USHIODA1992 Volume 42 Issue 2 Pages 121-123
Published: February 28, 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (297K) -
1992 Volume 42 Issue 2 Pages iv
Published: 1992
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (80K)
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