Microband formation in an IF steel during cold rolling at low strain levels

Abstract

Microband formation in an IF steel during cold rolling at low strain levels (ε≤9.8 %) has been investigated by using TEM. The formation of microbands starts at small reductions (ε ∼ 6.7 %), and microbands have habit planes running approximately parallel to {110} planes. In the specimen that was rolled to ε = 9.8 %, some grains contain one or two sets of microbands, while some are microband-free. The crystallographic measurement and deformation geometry calculation reveal that the habit plane of an observed microband has the largest Schmid factor; and when one 〈111〉 slip direction is intensively activated in this plane, one set of microbands is formed on this plane. Two sets of microbands form if two 〈111〉 slip directions are strongly and nearly equally activated. In the case of microband-free crystals, up to 7 slip systems have similar Schmid factors, are activated concurrently, and thus produce homogeneous deformation.