Effect of boron on planar anisotropy of r-value in extra-low-C IF steel sheet

The planar anisotropy of r-value was investigated of extra-low-C, Ti and Nb added interstitial-atom free (IF) steels with various B contents. The anisotropy of r-value is preferably decreased by addition of B, although mean r-value itself after cold rolling and recrystallization treatment is slightly lowered. Addition of B does not affect the grain size of hot band, leading to small influence on r-value in cold-rolled and annealed sheet. In the texture of the hot band, strong γ- and α-fibres, especially, {001}〈110〉, {332}〈113〉, {113}〈110〉 are formed by B addition. On the other hand, no specific sharp orientation is obtained in B-free steel. By cold rolling and recrystallization, these hot rolling orientations are rotated toward stable orientations. It is estimated that these hot rolling orientation in ultra-low-C IF B-bearing steel decrease the planar anisotropy of r-value after the cold rolling and recrystallization treatments.