Effects of processing routes on recrystallization texture development and magnetic properties of 0.10 mm ultrathin non-oriented electrical steel sheets for high-frequency application

Fabricating ultrathin non-oriented electrical steels (NOES) sheets has been a challenge because the severe plastic deformation inevitably results in undesirable texture such as intensive γ-fiber (<111>//ND). In the present work, both one-stage rolling route with severe plastic deformation and two-stage rolling route combining different rolling process and the intermediate annealing were used to prepare 0.10 mm-thick 3.1Si-0.8Al NOES. A rare phenomenon was found that severe plastic deformation in one-stage rolling route split the orientations of α (<110>//RD) grains through deformation banding and caused lattice curvature, exhibiting the similar microstructure characteristic and stored energy distribution as the deformed γ-grains. As a result, dominant α*-fiber ({1 1 h} <1 2 1/h>) and relatively soft α-fiber textures besides sharp γ-fiber recrystallization texture were formed, which seriously deteriorated the magnetic induction and led to high magnetic anisotropy. By comparison, the two-stage rolling route favored the development of shear bands and increased the final grain size. As the second rolling reduction decreased, detrimental γ- and α*‐fiber recrystallization textures were significantly weakened, whereas λ-fiber (<001>//ND) and {117}<291> recrystallization textures were enhanced. Besides, the final grain size was gradually increased. Therefore, the magnetic induction was continuously improved and the core loss was gradually decreased. Another new finding was that magnetic anisotropy was simultaneously improved as a result of the occurrence of {117}<291> texture and the weakening of α*-fiber texture. The recrystallization mechanism of specific texture components was investigated in detail.