The authors have published some papers concerned with anisotropic mechanical properties of structural rolled steels and described that tensile strength exhibits little or no directional properties but elongation and reduction of area decrease markedly as the angle between the test specimen axis and the rolling surface increases and approaches the thickness direction as seen in Fig 1 & 2.
In this paper, supposing that bended structures and brittle inclusions are probably important variables which contribute to the poor ductility in the thickness direction, the authors have studied the effects of these variables on the directionality or the ductility in the thickness direction. Based on the experimental results as shown in Figs 5(a)-5(e), 9, 11 and 12, it would be concluded that the directionality. in other woulds, the poor ductility in the thickness direction is more caused by the alignment and shapes of microscopic inclusons, then existence of the banded structure as found in hotrolled steels.