All issues
Volume 45, Issue 8
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
-
Koichi OGAWA, Hiroshi YAMAGUCHI, Yoshinao TAKASHIMA, Yoshiaki YAMAMOTO1995 Volume 45 Issue 8 Pages 435-440
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThis paper discussed the method which estimates non-destructively joint performance using welding behaviours. The welding behaviours such as friction torque, shape of burr, breaking burn-off velocity, friction input and mean friction input were measured during friction process and the correlation between the welding behaviours and the joint performance (tensile strength) was examined. As a result, a high correlation coefficient between the combination of three friction behaviours, namely, steady torque, terminal peak torque and forging velocity and the joint performance was obtained. Moreover, three behaviours covered other welding behaviours. Thus, the first order equational model using three welding behaviours was considered and the welding evaluation formula which indicates level of joining was suggested. It was proved that the joint performance could be estimated approximately by the welding evaluation value Fw obtained using the welding evaluation formula.View full abstractDownload PDF (595K) -
Takeshi IKEDA, Miyuki TANAKA, Shin-ya KOMATSU1995 Volume 45 Issue 8 Pages 441-446
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEffect of heat treatment on electrical resistivity and tensile strength of Al-0.35mass%Zr-0.15mass%Fe-XSi (X = 0.05-0.15mass%) wire rods produced by Properzi continuous casting and rolling (PCCR) process were studied, and the microstructure was observed by transmission electron microscopy. Solute Zr and Fe concentrations in wire rods of various Si content were analysed before and after a heat treatment. In as PCCR state, solute Zr concentration, CZr, was decreased by 0.15%Si addition. After an isothermal treatment, CZr decreases with increasing content of Si. The addition of 0.10%Si accelerates the precipitation of Zr and enhances age hardening, while that of 0.15%Si shortens the time to over age softening. Though solute Fe concentration, CFe, becomes to almost equilibrium concentration of Al-Fe binary alloy at 723K, supersaturation of solute Zr is maintained even after isothermal treatment at 723K for 180ks. As the heating rate decreases, the reduction of tensile strength by recovery in an early stage of isothermal treatment decreases, and the maximum tensile strength increases due to age hardening, suggesting nucleation of β'-Al3Zr during heating.View full abstractDownload PDF (954K) -
Nobuaki OHNISHI, Tetsuya TAKAAI, Yoshihiro NAKAYAMA, Masahiro OHMORI1995 Volume 45 Issue 8 Pages 447-452
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEffect of high temperature solution treatment of AC4CH aluminum casting alloy was studied mainly in view of tensile properties, changes in resistance ratio, differential scanning calorimetry and variations of microstructures. Changes in resistance ratio were remarkable in accordance with the increase of the solution treatment temperature suggesting an effective solutionizing and promotive effect thereof. According to differential scanning calorimetry, the amount of endothermic reaction heat flow increased steeply in relation to the rising of the solution temperature, also indirectly suggesting an increase of the amount and extent of the solutionizing of the elements as being confirmed basing upon the electric resistance ratio measurements. Microscopic observations of the specimen solution treated at high temperature showed an effective globalization of eutectic silicon.View full abstractDownload PDF (957K) -
Toshikatsu ASAHINA, Kazuyoshi KATOH, Hiroshi TOKISUE1995 Volume 45 Issue 8 Pages 453-458
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSPure magnesium was friction welded using a brake type friction welding machine. Microstructures and mechanical properties of friction welded joints were investigated. The fine grain structure appeared near the weld interface, while a modified fiber structure is observed on the heat affected zone along the flow direction of burr. Hardness of the interface of the joint welded at friction pressure of 20MPa was higher than that of the base metal, but joints welded at friction pressure of 30 and 40MPa were nearly equal to that of the base metal. The tensile strength of welded joints increased with increasing both friction time and friction pressure, and the joint efficiency obtained about 87% of base metal. At friction pressure of 40MPa, the joint shows elongation which is higher than that of the base metal. The joints welded at friction pressure of 20MPa fractured at the weld interface, but the other joints fractured at the heat affected zone. The impact value of joints which are welded at friction pressure of 40MPa and notched at the weld interface, is 1.8 times larger than that of the base metal.View full abstractDownload PDF (2124K) -
Shin ORII, Shunzo AOYAMA, Teruyoshi UMEMURA1995 Volume 45 Issue 8 Pages 459-464
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAC4C aluminum alloy die castings of various thickness were reheated to a semi-solid temperature and rapidly cooled down into water. It has been confirmed that aluminum primary crystals in dendritic structure become spheroidized and evenly dispersed. The optimum structure is obtained from the thinest-walled die castings having fine equiaxed crystals. A pressing apparatus capable of compressing die castings at a semi-solid temperature was dedicated to evaluate the deformability of the products, processed in various heating conditions. It has been clarified that when 5mm thick die castings are heated up to 853-858K in approximately 600 seconds, and compressed at that temperature, sound products can be obtained, which have microstructure of about 50μ dia. spheroidized aluminum primary crystals.View full abstractDownload PDF (1862K) -
Hideaki SHIBATA, Keiro TOKAJI, Hirohisa SHIOTA, Yasuhito OHTA1995 Volume 45 Issue 8 Pages 465-470
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThis paper describes the fatigue strength and fatigue crack propagation (FCP) at ambient temperature in injection molded titanium aluminide, TiAl. Axial fatigue tests and FCP experiments have been conducted on injection molded materials which were sintered at 1350°C and 1400°C. The fatigue strength and FCP resistance of the injection molded materials were considerably lower than those of the cast material, and the material sintered at 1400°C showed higher fatigue strength and FCP resistance than the material sintered at 1350°C. These results may be attributed to many pores contained in the injection molded materials or in the material sintered at lower temperature, and also due to the difference in microstructure. The SEM examination of fracture surfaces revealed that translamellar cleavage, interlamellar cleavage, and cleavage of equiaxed gamma grains were predominant modes of fatigue failure in the injection molded materials.View full abstractDownload PDF (1516K) -
Shigeru OKANIWA1995 Volume 45 Issue 8 Pages 471-489
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (3843K) -
Kazunori KOBAYASHI1995 Volume 45 Issue 8 Pages 490
Published: August 30, 1995
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (127K)
- |<
- <
- 1
- >
- >|