Effects of initial microstructure and texture on microstructure, texture evolution and magnetic properties of non-oriented electrical steel

An equiaxed grained as-cast strip and a columnar grained as-cast strip was produced by using twin-roll strip casting, respectively. Both as-cast strips mainly containing 0.71 wt%Si and 0.44 wt%Al were cold rolled and annealed with or without the hot rolling prior to cold rolling. Microstructure, texture evolution along the whole processing routes and the magnetic properties were investigated in detail. It was found that the equiaxed grained strip was characterized by almost random texture while the columnar grained strip was dominated by strong lambda-fiber (< 001 > parallel to ND) texture. After cold rolling and annealing, all the final sheets of both the as-cast strips showed extremely weak gamma-fiber (< 111 > parallel to ND) re crystallization texture. In addition, the finally annealed sheets of the equiaxed grained strip were dominated by relatively weak lambda-fiber and strong Goss ({110} < 001 >) recrystallization texture while those of the columnar grained strip were dominated by much stronger lambda-fiber and much weaker Goss recrystallization texture regardless of whether the hot rolling was adopted before cold rolling, thus the former showed much lower magnetic induction than the latter. On the other hand, even though the finally annealed sheets of the equiaxed grained strip showed a little more homogeneous recrystallization microstructure with a little bigger grain size than those of the columnar grained strip in the case of no hot rolling, a much higher iron loss was displayed. By contrast, in the case of hot rolling, the former exhibited a little lower iron loss than the latter as a result of the more significant increase in grain size and lambda-fiber recrystallization texture. The introduction of the hot rolling could increase the grain size, strengthen lambda-fiber texture and weaken Goss texture of the finally annealed sheets of both the as-cast strips, leading to a much improvement in both the magnetic induction and iron loss. (C) 2016 Elsevier B.V. All rights reserved.