Deformation banding and recrystallization of α fibre components in heavily rolled IF steel

Abstract

Detailed SEM work has shown that about a quarter of crystals belonging to the α fibre formed by cold rolling up to reductions of 85%, are of uniform microstructure with relatively small misorientation. The remainder are indistinguishable from the polycrystalline mass, which is mostly of γ orientations. At rolling reductions above 85%, α grains begin to split their orientations by deformation banding, thus producing lattice curvature which allows recrystallization of α at the expense of other α components in the same original grain. This α recrystallization deteriorates the deep drawability of IF steel and since the process requires deformation banding a natural explanation of the optimum rolling reduction for good drawability is provided. The best cold rolling reduction is that which optimizes γ recrystallization by producing deformation banding in γ components without producing deformation banding in α components. Uniform microstructures and small lattice curvature allows α to be consumed by other orientations, and this condition is obtained in the 80-85% cold rolling range. © 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.