Anisotropy in rolled metals induced by dislocation structure

The flow stress anisotropy of rolled sheets of aluminium, copper and interstitial-free steel has been investigated by tensile testing. Strong anisotropy, i.e., larger than expected from the texture, was induced by the dislocation structure in aluminium and IF steel increasing with the rolling prestrain while no such effect was found in copper. Taking into account the different spacings, misorientations and crystallographic alignment of the dislocation boundaries as well as the texture induced by rolling in the three metals, the anisotropy was modelled as arising from the resistance to slip offered by parallel dislocation boundaries. Good agreement between prediction and experiment also concerning the absolute flow stress values was found for all three metals. The best agreement was for aluminium, where the dislocation structure has been most thoroughly characterized.