Abstract

Grain-oriented silicon steel is mainly used as the core material of transformers, and it is manufactured by applying secondary recrystallization. The driving force of this process is the grain boundary energy, based on the nature of the grain boundary, which is determined by coincidence site lattice (CSL) relations. CSL relations are determined by the arrangement of lattice points in three-dimensional space and have already been shown mathematically by using advanced mathematics. However, their derivation processes are abstract, making them difficult for material engineers to understand. Therefore, in this study, a derivation of CSL relations is attempted in order to enable material engineers to easily understand the derivation. This study contributes to industrial mathematics by helping material engineers understand the essence of the mathematical method in order to use it appropriately. Specifically, a derivation method for coincidence relations is proposed using the hexagonal lattice (in the case of an axial ratio of [Formula: see text]) as an example that avoids the need for advanced mathematics. This method involves applying the scale rotation of a quaternion, and it is thus named the quaternion-matrix method. The matrix specifying the [Formula: see text] coincidence relation of a certain lattice system is expressed by a similarity transformation using the matrix comprising its primitive translation vectors and is given as the following transformation matrix: [Formula: see text]. Based on the rational number property of the transformation matrix elements, the following formula is derived: [Formula: see text], [Formula: see text], [Formula: see text] value. Here, ([Formula: see text]) is specified by the integrality (lattice point) and irreducibility (unit cell) among the elements of [Formula: see text], and the quaternion for the CSL formation is thus derived. Finally, based on the polar form of this quaternion, the coincidence relation can be derived.

Highlights

  • Grain-oriented (GO) silicon steel is mainly used as the core material of transformers, and it is the only product in the steel industry that is manufactured by applying secondary recrystallization

  • NEi and NREi are expressed as the linear combination of primitive translation vectors (PTVs) for the coincidence site lattice (CSL) with integer coe±cients, which have no common factor among nine elements

  • CSL relations have already been shown mathematically by using advanced mathematics. These are abstract, making them di±cult for material engineers to understand their derivation

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Summary

Introduction

Grain-oriented (GO) silicon steel is mainly used as the core material of transformers, and it is the only product in the steel industry that is manufactured by applying secondary recrystallization. CSL relations are derived mathematically using advanced mathematics.2–10 Their derivation processes are abstract, making them di±cult for material engineers to understand their derivation. The denition of the CSL is \Two interpenetrating point lattices contain under certain conditions a common sublattice". It is thenest common sublattice of the crystal lattices formed with a three-dimensional lattice L (simple cubic, face-centered cubic, body-centered cubic, hexagonal, or whatever) and a three-dimensional lattice RL which is obtained by rotational transformation of L. The coincidence relation to be derived in this paper indicates the rotational axis and angle in three-dimensional space, and a right-handed coordinate system is applied.

Denition of CSL
Expanded lattice
Quaternion
Expansion and rotation of Es
Hh matrix elements using quaternion
Formula based on rationality of Hh matrix elements
H22: H23: m2 m3
Integrality and irreducibility
Examination of integrality
Examination of irreducibility
Calculation example
Conclusion
Denitions
Full Text
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