Preferential Growth of Secondary Recrystallized Goss Grains During Secondary Recrystallization Annealing in Grain Oriented Silicon Steel Sheet

Yukio Inokuti

doi:10.1155/tsm.26-27.413

Abstract

Computer color mapping of the primary and secondary recrystallized Goss grains which formed during secondary recrystallization annealing was performed with an image analyzer, using crystallographic orientation data measured by a Kossel examination.The preferential growth of secondary recrystallized Goss grains took place in a defined zone at the 1/10 depth beneath the surface of the as-decarburized and primary recrystallized steel sheet.With short-time secondary recrystallization annealing, a secondary recrystallized Goss grain with an 80 × 50 μ m elliptical form grew preferentially in its defined zone.With further secondary recrystallization annealing, four secondary recrystallized Goss grains coalesced to sizes of 100-350 μ m, and exhibited a zigag morphology due to a difference in the degree of consumption of primary recrystallized grains by the secondary recrystallized Goss grains. Primary recrystallized grains with {100} , {100} , and {100} orientations were resistant to comsumption by secondary recrystallized Goss grains, but those with {110} and {111} orientations were easily consumed by secondary recrystallized Goss grains.With long-time secondary recrystallized annealing, the full thickness of the silicon steel sheet was occupied by giant secondary recrystallized Goss grains, which ultimately extended to lengths of several millimeters. The orientation of the secondary recrystallized Goss grains is highly aligned to the [001] axis rather than the (110) crystallographic plane.It is considered that the nuclei for preferentially developing secondary recrystallized grains are inherited by the structure memory from highly oriented (110)[001] areas at the 1/10 depth beneath the surface of hot-rolled silicon steel sheet.

Highlights

The control of secondary recrystallized grains to obtain the Goss texture, (110)[001], is of vital importance in manufacturing silicon steel strip for transformer cores
To obtain samples of materials annealed for 3 h and 7 h at 850C for the transmission Kossel (TK) examination, thin samples were prepared by cutting the silicon steel sheets into 30 x 40 mm pieces, and which were mechanically ground on one side to a thickness of about 150/m
From the color maps of (B) in Figure 1, it can be seen that a secondary recrystallized Goss grain of elliptical form, 80 pm long in the rolling direction and 50 /m in the transverse direction, grew preferentially at the 1/10 depth beneath the surface of the silicon steel sheet

Summary

Introduction

The control of secondary recrystallized grains to obtain the Goss texture, (110)[001], is of vital importance in manufacturing silicon steel strip for transformer cores. The improvement of magnetic properties in grain oriented silicon steel sheet has been closely related to the history of improvements in the secondary recrystallized texture. Goss secondary nuclei for preferentially developing secondary recrystallized grains are generated from the highly oriented (110)[001] areas near the surface of hot-rolled silicon steel sheet. These highly oriented (110)[001 areas are inherited from the structure memory (Inokufi, 1988, Gol’ dshten et al, 1978 and Inokuti et al, 1982 and 1985)

Methods

Results

Discussion

Conclusion