Increasing desirable recrystallization texture in IF steel by controlled rolling

Abstract

A flat {111} <hkl> texture of high intensity in IF steels following the final anneal produces good drawability and this is usually derived from a fairly random hot band material. In the first part of this work, conventional hot band was subjected to a cold roll-anneal-cold roll-final anneal procedure in which the total reduction was 80% (i.e. gage control) but in combinations of for example 70%+10% or 10%+70%, The purpose was to find whether final rolling of essentially a {111}<hkl> (y) texture enhanced the intensity of {111}<hkl> in the final annealed conditions. Also the effects of whether the material was fully recrystallized, partially recrystallized or merely recovered after the first annealing was investigated. The results are encouraging in that {111}<hkl> could be increased when the texture before final cold rolling and annealing had a high y and low {hkl}<110> (α) fibre. An explanation is provided for this based on Deformation Band (DB) theory. The second part of the work concerned warm rolling of the hot band in the a phase region, using a single pass reduction of 75%. This was either annealed and cold rolled or just cold rolled to 80% reduction followed by a standard recrystallization treatment. The results show the greatest intensity of {111}<hkl> to be formed when the metal was cold rolled without intermediate annealing. Global textures were measured using X-rays, and the SEM techniques of EBSP and OIM coupled with conventional TEM and STEM were used for local texture and microstructures investigations.