Effect of Initial Orientation on the Cold Rolling Behavior of Solidified Columnar Crystals in a 19% Cr Ferritic Stainless Steel

The cold rolling behavior of solidified columnar crystals in a 19%Cr ferritic stainless steel has been investigated in order to clarify the effects of the initial orientation of each columnar grain and of the interaction with adjacent grains in a polycrystalline specimen. The specimen showed {001}≪uv0≫ texture before rolling and {001}[110] texture after 70% rolling reduction. It was clearly shown that the rolled microstructure and the crystal rotation by rolling strongly depend on the initial orientation. The 70% rolled microstructure of (001) [100] oriented grains consisted of a large number of fine stringer deformation bands, whereas (001)[110] oriented grains showed a uniform and non-characteristic deformation structure. In the grains having intermediate orientations such as (001)[510]-[320], stringer deformation bands formed near grain boundaries. Both of the (001) [100] and (001) [110] oriented grains maintained their initial orientations even after 70% rolling reduction, while the (001)[510]-[320] oriented grains rotated toward (001) [110]. It was emphasized that the stability of (001)[100] oriented grains against rolling is contrast to the case of (001) [100] oriented bcc single crystals where the crystal rotation toward (001) (110) occurs. This difference was discussed from a viewpoint of the interaction with adjacent grains.