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Volume 30, Issue 3
Displaying 1-9 of 9 articles from this issue
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Kentaro MIZOGUCHI1980 Volume 30 Issue 3 Pages 119-120
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
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Akira NISHIMURA, Yutaka KAWANO1980 Volume 30 Issue 3 Pages 121-127
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSA quasi grain model made of compressed lead balls was applied to determine a correction factor for conversion of an actual grain structure into spherical one. The correction factor is 0.96 to 0.97. A computer simulation method using a statistical interception model was proposed to estimate the spatial sphere distribution from plane circle one. Two hundred sphere samples are required to ensure successful approximation for the actual interception of spheres by the interception model. This computer simulation permits a better result than the Schwartz-Saltykov and Saltykov methods except for the standard deviation in the Schwartz-Saltykov method.View full abstractDownload PDF (1147K) -
Munenori SHINOHARA, Fumihiko UCHIDA, Matsuo MIYAGAWA1980 Volume 30 Issue 3 Pages 128-134
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSTensile tests of smooth and notched bar specimens were carried out under hydrostatic pressures up to 4000 kgf/cm2. The reduction of area in the smooth specimens increases with increasing the pressure, but the uniform strain does not. These facts suggest that plastic workings under hydrostatic pressure are usually favorable in the working limit, but some workings such as bulging in which the working limit is governed by instability are not so favorable. Notched specimens of A2014-T6 brittlely fractured. The finite element method was used for an elasticplastic analysis of this problem. The plastic stress concentrates at a point slightly inner from the root of notch. This point concurs with the origin of void. The central part of the notched specimen remains to be in an elastic state at fracturing. Growth of voids is restrained by hydrostatic pressure. The fracture load of the notched specimen increases with increasing pressure.View full abstractDownload PDF (897K) -
Shigeo OYA, Akira SUDO, Satoshi MATSUMOTO1980 Volume 30 Issue 3 Pages 135-139
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSColumnar crystals of pure aluminum were competitively grown at various G/R in <100>, <110> and <111> directions from seed crystals. Crystals having <111> growth orientation preferentially grow under such a condition that a planar solid-liquid interface advances at high G/R. Crystals having <100> growth orientation, on the other hand, preferentially grow similarly as dendritic growth under such a condition that the interface forms hexagonal or broken cells at low G/R. When the interface forms irregular or elongated cells, <100>, <110> and <111> orientations stably advance accompanying by little preference. The <111> and <100> orientation preferences are built up in the mechanisms that a crystal extends to the direction perpendicular to the growth direction and that a crystal prejects ahead of the mean interface respectively. The preferred growth is explained on the basis of the {111} platelet growth theory.View full abstractDownload PDF (952K) -
Eiji KATO, Toshiro KOBAYASHI1980 Volume 30 Issue 3 Pages 140-146
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSFracture toughness of unidirectionally solidified Al-7%Si and Al-7%Si-0.3%Mg alloys is evaluated as a function of cooling rate. The toughness of the Al-7%Si alloy is slightly improved when the primary and secondary arm spacings and the particle size of silicon are reduced with making fast the cooling rate. Cracks are initiated at the matrix-silicon particle interface by cleavage of silicon particles. The initial cracks at coarse silicon particles are interconnected and propagated. If the silicon particles are refined at faster cooling rate, the plane strain fracture toughness is raised. Coarse silicon particles are easily fractured. Fracture toughness of the Al-7%Si-0.3 Mg alloy is not so susceptible to the cooling rate because the dissolution of magnesium into the matrix and solution hardening oecur.View full abstractDownload PDF (2142K) -
Eiji KATO, Toshiro KOBAYASHI1980 Volume 30 Issue 3 Pages 147-153
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSFracture toughness of unidirectionally solidified Al-7%Si and Al-7%Si-0.3Mg alloys was evaluated. Size, shape and distribution of silicon particles were varied by controlling freezing rate and subsequent solution heat treatment time at 530°C. Refining and morphological change of the silicon particles from acicular to granular by prolonged solution heat treatment cause considerable increase in the absorbed energy. Increase in the absorbed energy of the alloys solution treated for a short time up to 5hrs was resulted from increases both in initiation (Ei) and propagation energies (Ep), and that for a prolonged time was resulted only from increase in Ep. Proper solution heat treatment of the alloys having smaller arm spacing leaded to higher impact strength because of the difficulty of crack propagation. The fracture toughness was increased with reducing the radius of curvature at the tip of silicon particles. The alloys solution heat treated for 5hrs contained finest silicon particles and had the maximum fracture toughness.View full abstractDownload PDF (2273K) -
Motohiro KANNO, Hisashi SUZUKI, Osamu KANOH1980 Volume 30 Issue 3 Pages 154-160
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSTransmission electron microscopic studies of the alloy solution treated at temperatures above 520°C and aged at 200°C were mainly made to clarify the cause of development of fine dislocation loop structure with increasing amount of additional Sn. Dislocation loops generally originate at anearly stage of aging from Sn-rich precipitates. Some quenched-in vacancies are initially included in Sn-rich precipitates and concurrently those in matrix rapidly diffused toward the precipitates as aging proceeds. The fine dislocation loop structure in the ternary alloy is caused by fine distribution of the Sn-rich precipitates. Observed acceleration in the growth rate of θ' precipitates (heterogeneously formed from Sn-rich phases) would be due to excess vacancies retained in the Sn-rich phases.View full abstractDownload PDF (2792K) -
Yo KOJIMA, Tsuneo TAKAHASHI1980 Volume 30 Issue 3 Pages 161-167
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
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Susumu INUMARU1980 Volume 30 Issue 3 Pages 168-180
Published: March 31, 1980
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2374K)
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