Cube-oriented regions in inhomogeneous rolling texture and recrystallization texture of high purity aluminum sheets

For the production of thin high-purity aluminum foils for capacitor, it is essential to develop cube texture in the foils. The foils are produced in the following way: hot-rolled plates are cold-rolled by high reduction, intermediately annealed at a relatively lower temperature to cause primary recrystallization, then cold-rolled by a small amount and finally annealed at a higher temperature to develop cube texture. In this work, a crystallographic orientation distribution of a cold-rolled sheet with high reduction was examined in comparison with that of a primarily recrystallized sheet to study the mechanism of cube texture development in the foils. The orientation on a transverse section of these sheets of 500 mum in thickness were studied by electron back-scatter diffraction pattern measurements. The results are summarized as follows: (1) The cold-rolled sheet showed an elongated layered structure, nearly parallel to the rolling direction. Although there were large misorientation angles between layers, every layer contained many fine regions with small misorientation angles. (2) In the inhomogeneous cold-rolled sheets, fine cube-oriented regions were already present at certain position: 15 mum, 80 mum from the surface and in the central part. They were most frequently observed at about 80 mum. (3) In the primary recrystallization texture, cube grains were frequently observed 80 mum to 200 mum in the depth from the surface. It is considered that fine cube-oriented regions are closely related to the development of cube texture in the annealed sheets for capacitor.