軽金属
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
54 巻, 3 号
選択された号の論文の7件中1~7を表示しています
研究論文
  • 竹上 弘彰, 篠田 剛
    2004 年 54 巻 3 号 p. 95-99
    発行日: 2004年
    公開日: 2007/02/20
    ジャーナル フリー
    In friction welding, heat input is significant factor, which affects the quality of welded joints. It is difficult to calculate the heat input, because friction heating is complicated phenomenon. Therefore, there is no general calculation method in friction welding. As one of the parameter for calculation, friction torque is used. However, torque meter is not generally installed into friction welding machine. Torque is not the parameter, which can be used with all friction welding machine. Authors have proposed the method of alternative calculating, which is calculated using the upset distance. In this study, the two calculating methods were compared and the validity of both the calculating method was examined. It was revealed that heat input could calculate in accuracy equivalent to using torque by calculation using upset distance.
  • 篠嶋 妥, 市村 稔
    2004 年 54 巻 3 号 p. 100-104
    発行日: 2004年
    公開日: 2007/02/20
    ジャーナル フリー
    Directional solidification simulation of Al–Zn binary alloy was performed using the phase field method. The result was visualized, and the influences of Zn composition C0, temperature gradient G, and growth velocity V on the stability of planar interface and crystal growth form were investigated.
    With increasing growth velocity V, the morphology of solid-liquid interface changed from planar interface to plane with hollows, and finally to cell-like segregated structure. The curvature of the tip of the cell-like structure R became small and the spacing between the cells decreased with increasing V. The stability region of planar interface was determined by the value of G/V and Zn concentration C0. It turns out that the boundary of the stability region of planar interface is a linear function of C0 such that G/V [K·s/m2]=2.78×109×C0 [at%], where the value of the slope was about 70% of that of the prediction of the constitutional undercooling theory. It was also found that the spacing between the cell-like segregated structures agrees well with the dendrite growth theory.
  • 高橋 昌也, 米山 猛
    2004 年 54 巻 3 号 p. 105-109
    発行日: 2004年
    公開日: 2007/02/20
    ジャーナル フリー
    Isothermal extrusion is a method of maintaining constant temperature of an extruded section in the bearing zone of the die in order to get a high steady qualities in mechanical properties. Isopressure extrusion is a method of maintaining the load on the die constant throughout the ram stroke in order to get a high steady qualities in dimensions of extruded sections. In this study, an equation for calculating the initial billet temperature that performs isothermal and isopressure extrusion is proposed and confirmed. The idea is derived from the concept that the heat flow from the billet to the container is made to be equal to the heat generation by the shearing deformation of metal close to the container wall. Applying an adequate initial billet temperature obtained from the simple equation, constant temperature and constant die load have been achieved and excellent steady dimensions and mechanical properties have been obtained from the isothermal and isopressure extrusion.
  • 箕田 正, 渋江 和久, 吉田 英雄
    2004 年 54 巻 3 号 p. 110-114
    発行日: 2004年
    公開日: 2007/02/20
    ジャーナル フリー
    It is well known that Lüders bands form in Al–Mg alloy sheets by tensile deformation. The Lüders bands are classified in two types; type-A and type-B. In this study, the influence of stress ratio of biaxial tensile test on the type-B Lüders band formation in an Al–5.5mass%Mg–0.3mass%Cu alloy sheet was investigated. The type-B Lüders bands were observed at the stress ratio (R.D. : T.D.) from 8 : 0 to 8 : 6, and they were not observed at 8 : 7 and 8 : 8. The mechanism of Lüders bands formation was considered as below. In the case of uniaxial tensile deformation, the slip planes were limited easily because of pinning of dislocations by magnesium atoms. The deformation did not occur uniformly, then the type-B Lüders bands occurred. On the other hand, multiple slip occurred easily in the case of balanced biaxial tensile deformation. Then, the sessile dislocations formed easily and the deformation occurred uniformly. Moreover, the type-B Lüders bands formed at an angle of 57 degrees to the applied load in the case of uniaxial tension, while 90 degrees in the case of plane strain tension. It was considered that the change of the Lüders bands direction occurred because of the difference of the activated slip system.
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