研究論文
Al–Mg系合金板材のリューダース帯形成に及ぼす2軸引張荷重比の影響
2004 年 54 巻 3 号 p. 110-114
詳細
2004 年 54 巻 3 号 p. 110-114
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.
