The Growth of {1 1 h}〈1 2 1/h〉 (α*-Fiber) Grains and the Evanesce of {001}〈100〉 (Cube) Grains During the Recrystallization of Warm Rolled Fe-6.5 Wt Pct Si Non-oriented Electrical Steel

〈001〉//ND (normal direction) texture (including the cube, {001}〈100〉) is a desired final texture in non-oriented electrical steel (NOES) due to the alignment of two magnetically easy 〈100〉 axes in the magnetization directions of the lamination core in rotating machines. However, after conventional rolling and annealing, the final texture of NOES is usually not the desired 〈001〉//ND texture, but the unfavorable 〈111〉//ND (γ-fiber), 〈110〉//RD (rolling direction) (α-fiber), and sometimes {1 1 h}〈1 2 1/h〉 (α*-fiber) textures. How do these textures (especially the α*-fiber texture) form in the recrystallization process is still not completely understood. This paper investigates the recrystallization process of a warm rolled NOES containing 6.5 wt pct Si and tracks the growth of individual grains using a quasi in-situ EBSD (electron backscatter diffraction) technique. It is shown that the {1 1 h}〈1 2 1/h〉 (α*-fiber) grains (including {001}〈120〉, {114}〈481〉, and {112}〈241〉) normally form in the later stage of recrystallization, and mainly nucleate in the mid-thickness region of the deformed steel from grains having the 〈110〉//RD (α-fiber) orientations. Once nucleated, they can rapidly grow into the deformed matrix due to the large energy difference between the recrystallized and deformed grains and to the high-mobility grain boundaries with respect to the deformed matrix. On the other hand, although cube grains nucleate early during recrystallization, they cannot grow significantly into the deformed grains because of the very high misorientation angles with respect to the deformed grains, which may have caused “orientation pinning”. As a result, the cube grains are finally consumed by the large α*-fiber grains due to size disadvantage. The origins of the α*-fiber grains and cube grains are also analyzed using the quasi in-situ EBSD data obtained in the early stages of annealing.