Goss Texture Development in Fe–Si Steels

N Rajmohan,Y Hayakawa,J A Szpunar

doi:10.1155/tsm.32.153

N Rajmohan, Y Hayakawa + Show 1 more

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https://doi.org/10.1155/tsm.32.153

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Abstract

Goss texture development in silicon steels has been studied through EBSP measurements and various computer simulations and calculations. The results of these studies suggest the possible role of high energy grain boundaries (HEGB) in the abnormal growth of Goss grains. The Goss orientation has a fraction of HEGBs that is higher than any other commonly observed orientations in the primary recrystallized silicon steels. The HEGBs have high GB diffusion coefficients which cause rapid coarsening of precipitates on these HEGBs and release them earlier, at the time when other GBs are still pinned. A difference in the mobility between the HEGBs and the other GBs favours the abnormal growth of Goss grains. The Monte-Carlo methods that have been developed and used to validate this assumption have generated abnormally growing Goss grains. The experimentally observed grain boundary character distributions (GBCD) around the growing Goss grains have been reproduced in simulation by assuming high mobility to HEGBs. Apart from the high mobility differences between different GBs, the importance of the fraction of GBs with high mobility around growing Goss grains is realized.

Highlights

The grain oriented silicon steels have been known since the work of Goss (1934), the mechanism of the development of Goss texture during secondary recrystallization (SR) is still under debate among researchers
As far as the CSL boundaries are concerned they do not play an important role in the abnormal grain growth (AGG) as the value of matrix fraction (MF) under the assumption that the CSL boundaries 3-51 are ’allowed’ is always less than 30%
The SR in Fe-Si steels is dominated by the influence of high energy grain boundaries (HEGB) which have a high mobility and high grain boundary diffusion coefficient

Summary

INTRODUCTION

The grain oriented silicon steels have been known since the work of Goss (1934), the mechanism of the development of Goss texture during secondary recrystallization (SR) is still under debate among researchers. Regarding the type of boundaries responsible for the growth of Goss grain in Fe-Si steel, one group of researchers (Harase et al, 1986; 1991; Shimizu et al, 1990; Abbruzzese et al, 1992; Lin et al, 1996) argue that certain coincidence site lattice (CSL) boundaries have high mobilities which result in AGG. Aspects of grain growth have been studied by our group (Hayakawa and Szpunar, 1997a,b; Hayakawa et al, 1996; 1997; Rajmohan et al, 1997) These studies using texture measurements, OIM and computer simulation methods reveal the importance of HEGBs. The purpose of this article is to explain the possible role of HEGB in the development of Goss texture in silicon steels. The following sections of this article delineate our investigations made to reveal the mechanism of Goss texture development in both conventional and high permeability Fe-Si steels

THE ROLE OF THE HIGH ENERGY GRAIN BOUNDARY

COMPUTER SIMULATION OF GOSS TEXTURE DEVELOPMENT

IMPORTANCE OF MOBILE BOUNDARY FRACTIONS

Findings

CONCLUSION