Deformation Structure and Recrystallization of Ferritic FeSi Steels

The magnetic properties of finally fabricated nonoriented FeSi electrical steels depend critically on microstructure and crystallographic texture components. The resulting microstructure and texture are influenced along the whole processing route of Fe–Si steels: hot rolling, coiling and cooling, hot band annealing before cold rolling (optional), cold rolling, and final thermal treatment. There is an interplay of microstructure and texture between the various processing steps, which is not investigated in any detail. Especially for ferritic FeSi steels are no specific investigations on the influence of microstructure and texture of cold-rolled material on their evolution at final annealing. In this paper, authors summarize the recent experimental results on the evolution of microstructure and texture at final annealing for cold-rolled material of ferritic FeSi steels with 2.4 and 3 wt% Si. The evolution of microstructure and texture is analyzed by metallographic studies and EBSD. Special attention is paid to the through-thickness dependence of microstructure and texture, which is caused by the strain gradients as well as thermal gradients at processing. The obtained experimental results altogether demonstrate clearly the effect of different misoriented substructures after cold rolling due to nonuniform strain on recrystallization behavior for the ferritic FeSi steels.