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Volume 52, Issue 5
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RESEARCH REPORT
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Yubo WANG, Kazuhiro MATSUGI, Tomei HATAYAMA, Osamu YANAGISAWA, Hiroyuk ...2002 Volume 52 Issue 5 Pages 199-203
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSAluminum matrix composite sheets, two-dimensionally reinforced with stainless steel mesh, were prepared by powder rolling and spark sintering. Tensile tests of the sintered samples were carried out to investigate the optimization of the preparing condition. Bonding of powder particles was promoted by sintering at higher temperature and for longer holding time. On the other hand, the intermetallic compound Alx(Fe, Ni, Cr) layer was produced at the interface between the stainless steel wire and aluminum matrix in the sintering process. The thickness of the intermetallic compound layer becomes larger at higher sintering temperature and for longer sintering time. Under the most suitable condition that the aluminum matrix is sintered enough and the thickness of the intermetallic compound layer is not so large, the maximum tensile strength of the composite is obtained. Under the conditions, the strength of the composite sheet increases and the elongation hardly changes with increasing volume fraction of stainless steel mesh to about 20%.View full abstractDownload PDF (483K) -
Yoshio OHUE, Katsuyoshi MORIKAWA, Koichi OGAWA, Hideaki NAKAYAMA2002 Volume 52 Issue 5 Pages 204-209
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSWelded joint performance of joints welded by the friction welding method has been studied for various material combinations because the method can more easily produce a combined shaft in comparison with other fusion welding method. In this study, 6061 aluminum alloy to S35C carbon steel were friction welded under three different friction welding conditions; and tensile and fatigue tests were conducted to obtain its strength characteristics in relation to the base material strength. As the result, the following were clarihed: Joint performance of friction welded joints is dependent on friction welding conditions; for this material, P2 (MPa) may be selected so that a friction welding condition for obtaining over 80% joint efficiency may exceed P2/P1=5 as P1=20 MPa. The HAZ region of low hardness exists by friction heat in the aluminum alloy side near the weld interface. Though it fractures in tensile tests from the softening region and in the fatigue test, there is a case in which it fractures in a weld interface. Therefore, fatigue strength decreases from the value estimated from tensile strength; attention to this fact is required when it is designed as a structural member. A particular structure near the weld interface exists, and since even if identical friction welding is adopted for all joints, the structure is delicately different so that the structure affects fatigue crack generation. Therefore, it seems that the scatter of fatigue strength of friction welded joints is larger than that of the base metal by fracture formation.View full abstractDownload PDF (532K) -
Hidetaka AMANO, Shin-ya KOMATSU, Masahiko IKEDA, Tomohiro KOHMOTO2002 Volume 52 Issue 5 Pages 210-215
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSBy annealing at 423 K for more than 10 Ms, the resistivity at 77 K, ρ77, in 92% cold rolled Al-3.18 at%Mg alloy decreased beyond a calculated value based on 2.5 at%Mg, the previously reported equilibrium solubility. Therefore, it is obvious that this 60 years old solubility data was overestimated. Aluminum alloys containing 3.18 to 8.91 at%Mg were isothermally annealed at temperatures of 423 to 523 K for longer than 864 ks with measuring ρ77. Through plotting the resistivity values versus annealing time t to the power of – 1/3 and extrapolating to the t−1/3=0, the resistivity after infinite period annealing, ρ77∞, in equilibrium state was estimated. Because the ρ77∞ increased with Mg content, the ρ77∞ values were plotted versus total Mg content and were regressed linearly. Equilibrium solid solubility at each temperature was estimated on the plots as intersections of the regression lines and the formerly determined relation between solute Mg concentration and ρ77. The obtained equilibrium solid solubility of Mg below 473 K is lesser than the previous values. Temperature dependence of the solubility is expressed as ln(X⁄0.385)⁄1−2X=1.948−2230⁄T, where X is atomic fraction of equilibrium solute Mg concentration. The equilibrium solubilities obtained from the above equation are 0.73 at% at 373 K, 1.54 at% at 423 K, 2.83 at% at 473 K and 4.73 at% at 523 K.View full abstractDownload PDF (495K) -
Gen SASAKI, Shunsuke HARA, Makoto YOSHIDA, Nobuyuki FUYAMA, Toshio FUJ ...2002 Volume 52 Issue 5 Pages 216-220
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe effects of stirring condition and setting position of reinforcements on pore content in the composites fabricated by compo-casting process were investigated by the visualized model experiments using glycerin. Gas pores were introduced in composites by stirring blade and gas contained in as-received reinforcement particles. The distance between blade and liquid surface, the rotational speed of blade and the viscosity of matrix affect the entrapping of gas. Particles were mixed with matrix material completely by placing on the bottom of die. Then, Al18B4O33 particle and whisker reinforced AZ91D magnesium alloy composites were fabricated by the compo-casting under the condition acquired from the visualized model experiments. The reinforcements in the composites fabricated under the condition of 33% solid fraction were distributed uniformly. Refining of primary crystal and homogenous microstructure were acquired by using AZ91D chips as a starting material or whiskers as the reinforcement.View full abstractDownload PDF (555K) -
Masami NAKAMURA, Yukinobu OHKURA, Kazuhiko NAKAMURA2002 Volume 52 Issue 5 Pages 221-225
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSInfluence of hydraulic counterpressure on the deep drawability of an aluminum work hardening sheet, and the forming method for improving deep drawing limit are examined. When a 1050–H24 aluminum sheet is formed by hydraulic counterpressure deep drawing, the limiting drawing ratio decreases compared with one formed by the conventional deep drawing. This is caused by inverse bulging deformation generated between a punch and a die due to hydraulic counterpressure. The radial strain caused by the inverse bulging deformation concentrates on the punch profile radius, which causes the local decrease of sheet thickness. For this reason, it is impossible to encourage material inflow into the die from a flange part. For relieving locally concentrated strain caused by inverse bulging deformation, material inflow into the die from the flange part is necessary. For this purpose, a method to push the flange edge by radial pressure drawing is effective. In addition, for suppressing the inverse bulging deformation generated under high liquid pressure, a method to reduce a blank holder profile radius and restraining by the metallic mold is effective.View full abstractDownload PDF (359K) -
Tetsuya MOTOI, Kiyoshi FUKUOKA2002 Volume 52 Issue 5 Pages 226-230
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSFor productions of double rolled foils in aluminum alloy, it is important to obtain fine mat surface. Because pin holes on the thin foils formed by connection corrugation wave on mat surface and oil pit on bright surface. We have investigated that size and morphology of intermetallic compounds, linking with pin hole numbers. As results, it become clear that spherical AlFeSi compounds increased non-flattening mat surface than plate AlFe compounds. The spherical AlFeSi compounds and the pin hole numbers in the foils were decreased by increasing Fe/Si ratios or homogenization annealing at higher temperature. These facts suggest that pin hole formation on the fine mat surface is more difficult than on the rough mat surface with spherical AlFeSi compounds.View full abstractDownload PDF (459K) -
Hiroki TANAKA, Hiroki ESAKI, Tadashi MINODA, Kazuhisa SHIBUE, Hideo YO ...2002 Volume 52 Issue 5 Pages 231-235
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe effect of temperature of the rolls from 2°C to 110°C in the warm roll process at 350°C was investigated in an attempt to refine the structure of the 7475 based aluminum alloy sheets including Zr which were heated after each roll pass. It was found that a lower temperature of the rolls led the alloy sheets to coarser grain structure after solution heat treatment. The {100} <011> Diagonal Cube component appeared in the surface layer, which suggested that strong shear bands had been formed during rolling in the layer. It was thought that these shear bands acted as nucleation sites for the recrystallized grains in solution heat treatment and contributed to the development of the coarse grain structure in the surface layer. Regarding the center region of the rolled plates, low temperature of the roll did not cause sufficient plastic deformation because of the cyclic occurrence of hardening and softening at the surface layer in the warm rolling process. Consequently, the center region also became coarse grain structure after solution heat treatment. On the contrary, in the case of a higher temperature of the rolls, the subgrain structure less than 3 μm was formed uniformly through the thickness of the plates after solution heat treatment with the strong Brass texture component.View full abstractDownload PDF (530K)
REVIEW
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Michikazu HARA2002 Volume 52 Issue 5 Pages 236-238
Published: 2002
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDownload PDF (305K)
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