Mechanism of Orientation Selectivity During Grain Growth of Secondary Recrystallization in Fe-3%Si Alloy

Y Ushigami,N Takahashi,T Kubota

doi:10.1155/tsm.32.137

Abstract

Selective growth of {110}〈001〉 grains in the temperature gradient annealing has been studied in Fe–3%Si alloy. As grains grow, the average deviation angle from the ideal {110}〈001〉 orientation becomes smaller and orientation distribution changes corresponding to that of coincidence grains in the matrix. Secondary recrystallization temperature depends on the orientation of secondary recrystallized grain and sharper {110} 〈001〉 grains grow preferentially at lower temperatures.These phenomena are explained by modified Hillert's model of grain growth. Interfacial energy of coincidence boundary is lower than that of general boundary. Therefore, sharper {110}〈001〉 grains, which have higher frequency of coincidence grains in the primary recrystallized matrix, suffer lower pinning effect from the second phase particles and thus grow preferentially at lower temperatures.

Highlights

Grain oriented silicon steel is a soft magnetic material widely used for transformer cores
The major differences between these processes are in the following two respects: (1) primary recrystallization texture; the CGO process involves two stage cold rolling with an intermediate recrystallization annealing and the HI-B process a single stage cold rolling with heavy reduction of about 87% compared to the final reduction of about 50% in the CGO process
Orientation of individual secondary grains was measured and represented as the deviation angles from the ideal Goss orientation around three axes; normal direction of the sheet (ND), rolling direction (RD), and transverse direction (TD)

Summary

Introduction

Grain oriented silicon steel is a soft magnetic material widely used for transformer cores. If the preferred orientation of { 110} (001) is developed, the product has superior magnetic properties, such as low core loss, low magnetostriction and high permeability, along the rolling direction. The principal process for developing Goss texture was invented by Goss in 1934 (Goss, 1934; 1935) and industrialized by ARMCO in the 1940s [CGO: conventional grain oriented silicon steel] (Littmann, 1967). High permeability grain oriented silicon steels (average misorientations of 3-4) were developed mainly by NSC in the 1960s [HI-B] (Taguchi and Sakakura, 1969; Yamamoto et al, 1972). Depending on the difference of these final cold rolling reductions, { 110} (001) and { 111 } (uvw) are the major components of the primary recrystallization texture in the CGO process. On the other hand, (110}(001) is negligible and {111}(112) is the major component in the HI-B process (Flowers and Heckler, 1976; Mishra et al, 1986; Matsuo, 1989). (2) inhibitor; CGO utilizes MnS and HI-B AIN in addition to MnS for the grain growth inhibitor of primary recrystallized matrix

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