Reduction of Elongation Anisotropy of Roll-Cast Strips by Cold Rolling and Annealing

Abstract

Roll-cast strips are usually cold-rolled and annealed before forming. The elongation of these strips is known to be different between the casting and lateral directions after thinning by cold rolling. Whether cold rolling is the main factor determining the anisotropy of the elongation is not clear. Likewise, it is not clear whether the elongation anisotropy can be reduced by conventional cold rolling. Roll-cast strips have centerline segregation, forming a so-called band area. The relationship between the anisotropy of the elongation and these defects is not clear. A strip cast using an unequal-diameter twin-roll caster also has a band area but a strip cast using a single-roll caster equipped with a scraper has no centerline segregation or band area. Strips made this way were cold-rolled in the casting and lateral directions, and tensile testing was conducted on the cold-rolled and annealed strips. In this study, the ability of conventional cold rolling and one-time annealing to reduce the elongation anisotropy of a cast strip was clarified. Moreover, the influence of the band area and Fe impurities on the elongation anisotropy was determined.