Thermomechanical treatment for enhancing gamma fiber component in recrystallization texture of copper-bearing bake hardening steel

Abstract

► Steel for deep drawing is desired to have as high density of γ fiber as possible. ► A process has been developed to increase γ fiber density of CBBH steel sheets. ► The process comprises two first rolling–annealing processes. ► The first step process aims at seeding γ fiber grains. ► The second step process aims at the growth of the γ fiber seed grains. A two-step rolling–annealing process has been developed to increase the 〈1 1 1〉//ND (γ fiber) component in the recrystallization texture of a copper-bearing bake hardening steel. The two step process comprises the first rolling by a low reduction in thickness and subsequent annealing at 780 °C, followed by the second rolling by a high reduction and subsequent annealing at 780 °C. The first rolling process aims at seeding the γ fiber oriented grains, so that they can grow at the expense of differently oriented grains developed in the second rolling process. In this way the density of γ fiber component in the recrystallization texture of the bake hardening steel much increases compared with that in the conventional one-step rolling–annealing process.