Bachelor of Technology in METALLURGICAL AND MATERIALS ENGINEERING

Bachelor of Technology in METALLURGICAL AND MATERIALS ENGINEERING
Textural and Magnetic Properties of Cross-Rolled Silicon Steels
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of
Bachelor of Technology
in
METALLURGICAL AND MATERIALS ENGINEERING
By
AMAR JASPRIT DUNGDUNG (110MM0352)
RAKESH KUMAR SETHY (110MM0382)
DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY
ROURKELA
National Institute of Technology
Rourkela
CERTIFICATE
This is to certify that the thesis entitled, " Textural and Magnetic properties of Crossrolled silicon steels” submitted by Amar Jasprit Dungdung (110MM0352) and
Rakesh Kumar Sethy(110MM0382) in partial fulfillment of the requirements for the
award of Bachelor of Technology Degree in Metallurgical and Materials
Engineering at National Institute of Technology, Rourkela is an authentic work carried
out by them under my supervision and guidance.
To the best of my knowledge, the matter embodied in the thesis has not been submitted
to any other University/Institute for the award of any Degree or Diploma.
Date:
Prof. Santosh Kumar Sahoo
Dept. of Metallurgical and Materials Engineering
National Institute of Technology
Rourkela-769008
1
ACKNOWLEDGEMENT
We grab this opportunity to thank and express our profound gratitude and deepest
regards to our guide Prof. Santosh Kumar Sahoo for his exemplary guidance,
monitoring, support and constant encouragement throughout the course of our project
work. The blessings, help and guidance provided by him from time to time and even at
odd hours of the day was like water to a thirsty traveler and the knowledge he has
imparted to us shall carry us a long way in the journey of life on which we are about to
embark.
We also take this opportunity to express gratitude to Dr. B .C Ray, HOD, Metallurgical
and Materials Engineering for his cordial support, valuable information and guidance,
which helped me in completing this task through various stages.
This study would not have been a success without the supervision and support of Prof.
I. Samajdar, IIT Bombay.
It will be negligent on our part if we fail to thank Mr. Surjyakanta Panda, student in PhD
for his unselfish will for explaining us the subject. We are obliged to the staff members
of department of Metallurgical and Materials engineering for the valuable information
provided by them in their respective fields. We are grateful for their cooperation during
the period of our assignment.
Place: NIT Rourkela
Amar Jasprit Dungdung(110MM0352)
Rakesh Kumar Sethy
2
(110MM0382)
ABSTRACT
Silicon steels are widely used for their electrical applications in motors, generators,
small transformer cores due to their high permeability, low core losses and their uniform
magnetic properties in all directions of the material. The major processing steps
involved for the production of silicon steels are hot rolling, cold rolling and annealing.
The processing steps largely affect the texture of these steels which subsequently
improves the electrical properties of these steels. The objective of the present study is
to investigate the cross-rolling effect on texture development of silicon steels and its
magnetic/electrical properties. X- ray Diffraction (XRD) method is carried out on the
sample to understand the textural development. PC based Pulse Field Hysteresis Loop
Tester is used to estimate the magnetic properties. It is observed that the steels have
improved textural and magnetic properties.
Keywords: Silicon steel, texture, magnetic permeability, core loss.
3
CONTENTS
TOPICS
PAGE NO.
Certificate
1
Acknowledgement
2
Abstract
3
List of Figures
6
List of Tables
7
Chapter 1: Introduction
1.1 Background
9
1.2 Objectives
10
Chapter 2: Literature review
2.1 Silicon steels
11
2.2 Effect of alloying elements on silicon steels
11
2.3 Types of Silicon Steels
12
2.4 Texture
13
2.4.1 Grain orientation
14
2.4.2 Pole figures
15
2.4.3 Oriental distribution Function
17
2.4.4 Euler angles
17
2.4.5 Euler space
19
2.4.6 Texture Developments in Silicon steels
20
2.5 X-ray diffraction
22
2.5.1 Features of X-Ray Diffraction Method
22
Chapter 3: Materials and Experimental Procedure
3.1 Materials
24
3.2 Texture characterization
24
4
TOPICS
PAGE NO.
3.3 Magnetic properties
24
Chapter 4: Results and Discussion
25
Chapter 5: Summary and Recommendation
32
References
33
5
LIST OF FIGURES
Fig no.
2.1
2.2
Caption
Page no.
Typical processing stages of non-oriented electrical steel.
The main issues involved in such steps are indicated.
13
a) Material without texture,
b) Material with a crystallographic texture,
14
(c) Material with morphological texture.
The small cubes represent the crystallographic orientation of
the grains.
2.3
2.4
Examples of crystal orientations in sheet (a) and wire (b), expressed
with Miller indices. The three cube axes are shown as xc, yc and zc.
15
Polycrystalline specimen
16
2.4 (a) Pole Figures
16
2.4 (b) Pole figure without texture
16
2.4 (c) Pole figure with texture
16
2.5
Orientation of the crystal axis system {Xic} and the sample axis system
{RD, TD, ND}; s is the intersection of the planes (RD–TD) and ([100]–[010])
18
2.6
Definition of the Euler angles φ1, Φ, and φ2 in the Bunge convention
18
2.7
Graphical representation of crystallographic orientations with Euler angles
19
2.8
Schematic representation of the most important texture components in the
φ2=45°section of ODF
22
2.9
Basic method of X ray Diffraction
23
4.1
ODF plot, at constant 2, of CRNO sample in the rolling direction.
26
6
Fig no.
4.2
Caption
Page no.
ODF plot, at constant 2, of CRNO sample in the direction 45o
27
to the rolling direction.
4.3
ODF plot, at constant 2, of CRNO sample in the transverse direction.
4.4
Volume fraction of cube, (001)<100> and goss (110)<001>
28
orientation at different directions of CRNO sample
29
4.5
Estimated core losses of CRNO sample at different directions.
30
4.6
Estimated permeabilities of CRNO sample at different directions.
31
7
LIST OF TABLES
Table No.
Caption
Page No.
3.1
Chemical composition (in wt. %) of Silicon steel sample
8
24
CHAPTER 1
INTRODUCTION
1.0 BACKGROUND
Silicon steel or Electrical steel was developed at the beginning of the 20th
century and soon was widely used as the preferred core material for large transformers,
motors, and generators. Silicon-bearing steels are used as soft magnetic materials in
electrical appliances and devices and are rated in terms of power loss when magnetized
in an alternating electric field.
Two important metallurgical factors that are responsible for the above said
properties are grain size and texture [1]. As grain size increases, hysteresis loss
decreases due to increase in domain width, and eddy current loss decreases [2]. So,
there is an optimum grain size which determines the sum of hysteresis loss and eddy
current loss to a minimum value. The existence of an optimum grain size can be
explained from domain theory, which can be demonstrated as, below the optimum grain
size hysteresis loss due to domain wall interactions is predominant while above the
optimum grain size losses are linked to domain wall movement.
Texture is one of the most important parameters determining the magnetic
properties of steel sheets. The ideal texture of non-oriented silicon steel sheets would
be a cubic texture with grains with their (001) or (110) planes parallel to the plane of the
sheet and a uniform distribution of the [100] direction, whereas the Goss texture with a
(110)[100] crystallographic orientation of the grains is the typical grain structure of grainoriented silicon steel.[3]. Material with a texture favorable for magnetic properties shows
lower core loss than those with an unfavorable texture, although they may have same
grain size [4]. Thus, (001)<uvw> texture component is the most desirable while
(110)<uvw>
is the most preferable and (111)<uvw> is the most avoidable texture
component in a Silicon steel[5]. So it is very important to link between the metallurgical
factors and magnetic properties before producing certain equipment [6]. The texture of
the silicon steel is controlled by subjecting the sample to hot rolling then cold rolling
followed by annealing.
9
1.1 OBJECTIVES
Study the variation in texture of cross-rolled silicon steel with respect to angular
direction, i.e., 1) rolling direction 2) 45° to the rolling direction 3) transverse
direction.
Determination of magnetic properties like core loss and permeability of the cross
rolled Silicon steel sample.
10
Chapter 2:
LITERATURE REVIEW
2.1 SILICON STEELS
It is one of the most strategic magnetic materials produced today. Silicon steel or
Electrical Steels are essential in the fabrication of a number of electrical equipment such
as transformer cores and are a preferred core material for equipments like motors and
generators [7].
The properties of these steels are:
1. High permeability
2. High magnetic induction
3. Low magnetic losses
4. Low magnetostriction
High permeability and induction effectively reduces the weight and size of the parts
leading to the increase in efficiency, lowering the magnetic losses reduces the
generation of core losses and subsequently the energy consumption, thus helping in
the minimization of the energy and a low magnetostriction reduces the noise in the
transformers and other high capacity machines by the production of less humming
sound [8].
Importance of silicon
In late 19th century when discovery of Si additions to increase the resistivity without
affecting the saturation magnetization significantly electrical steel was developed.
The addition of Silicon to iron has the following effects.

The electrical resistivity is increased. Thus, the eddy currents and
subsequent losses are lowered.
11

There is an increase in permeability due to decrease in magneto
crystalline anisotropy.

Decrease in magnetostriciton.

Reduction in the saturation induction.

When the Si percentage is greater than 3% there is an increase in the
brittleness of steel.
2.3 TYPES OF SILICON STEELS
There are generally 2 different types of Si steels.


Grain oriented Silicon steel (GO)
Grain non oriented Silicon steel. (GNO)
GO steels are the only class of material with ‘complete’ texture control through TMP,
‘the product is characterized by a high magnetic moment approaching that of a single
crystal, and the grains of the materials being substantially oriented at random
throughout the structure. The characteristics crystallographic orientation obtained from
TMP was named as Goss texture or {110}<001> preferred orientations.
GO steels primarily find application as core material for power and distribution
transformers where a directional magnetic flux in desired. The Goss texture has <100>
direction, which is the direction of easy magnetization parallel to rolling direction.
Although GO silicon steel has attracted more attention due to its properties, GNO steels
are being the highest tonnage of electrical steels being produced today [9, 10]. Grain
non-oriented silicon steel does not show a high Goss texture and thus, one of its main
commercial use is in rotating electrical machinery in which the magnetic field is in the
plane of the sheet, but the angle between the electric and magnetic field and the rolling
direction continuously changes. Considering the case of rotating machineries’ like
motors, it is pointless to have a direction of easiest magnetization, i.e. <100>, parallel to
the RD and an adequate texture would be {100}<uvw>, also known as <100> fiber
texture [11]. The processing of GNO electrical steel comprises hot rolling which may be
with annealing or without annealing followed by cold rolling in one or two steps with an
intermediate annealing and later on undergo final annealing and coating. The GNO
steel may be termed as Silicon steel i.e. cold rolled non-oriented steel and GO steel as
12
CRGO i.e. cold rolled grain oriented steel. Figure 2.1 shows the processing stages of
non-oriented electrical steels
Fig 2.1 Typical processing stages of non-oriented electrical steel. The main issues involved in such steps
are indicated. [12]
2.4 TEXURE
The magnetic property is dependent on the Orientation of grains/crystals is of silicon
steels. Orientation of grains/crystals is also a deciding factor for determining the
magnetic property of silicon steels. When the orientation of grains are statistically
distributed at random, the material is said to be crystallographic isotropic and shows no
preferred texture. However, if they are not randomly oriented, the material has a
crystallographic texture. The term ‘crystallographic’ is used here only because the
material can also show morphological texture as shown in Figure 2.2(c)[13].
13
Fig 2.2 (a) material without texture, (b)a material with a crystallographic texture, (c) a material with
morphological texture. The small cubes represent the crystallographic orientation of the grains.[13]
Crystallographic texture can be represented either by pole figure (PF) or orientation
distribution function (ODF).
2.4.1. GRAIN ORIENTATION
It is very important for us to understand the concept of grain orientation and its
representation before going into the concepts of PF and ODF. The orientation of a grain
is always expressed relative to an external coordinate system. In flat products (plates,
sheets), the external reference frame traditionally consists of the rolling direction (RD),
the normal direction (ND) and the transverse direction (TD)[14]. Any crystal orientation
can be expressed with the help of Miller indices and is written as: (hkl)[uvw]. This
represents that the direction [uvw] is parallel with the RD and a plane (hkl) is parallel
with the rolling plane. For example, the orientation of the crystal as in Figure 2.3 (a)
should be written as (001)[1-10]. When all the crystallographic equivalent orientations
are considered, the Miller indices are expressed as {hkl}<uvw>. In axisymmetric
products (wires, extruded bars), one set of Miller indices [uvw] is used to describe the
crystal orientation, indicating that this crystallographic direction is parallel with the
14
sample axis, e.g. [111] in Figure2.3(b). All rotations around [uvw] are crystallographic
equivalent [15].
Fig 2.3 Examples of crystal orientations in sheet (a) and wire (b), expressed with Miller
indices. The three cube axes are shown as xc, yc and zc. [14]
2.4.2. POLE FIGURES:
Pole figures in the form of stereographic projections are used to represent the
orientation distribution of crystallographic lattice planes in crystallography and texture
analysis in materials science.[14]
Considering the polycrystalline specimen shown in Fig. 2.4, there are three grains. Each
grain shows a definite orientation. In order to measure the {111} pole figure, we
consider the distribution of directions normal to the {111} plane in each grain. This
direction is also called {111} pole. As shown in Fig. 2.4, this {111} pole of each grain
points into different directions represented by P1, P2 and P3 respectively. Each pole
possesses its own coordinates in the sample reference frame. According to these polar
coordinates, the poles are plotted as shown in Fig. 2.4(a). The stereographic projection
thus obtained is called "pole figure". In actual situation, there will be millions of grains
which are measured at one time and therefore many dots will appear on the pole
figure. If the specimen is not textured the dots on the pole figure are distributed
randomly and do not form any special pattern as shown in Fig. 2.4(b). Otherwise, a
15
clustering of the different poles is observed as shown in Fig. 2.4 (c). Such pattern
indicates that the specimen is textured.
Fig 2.4: Polycrystalline specimen
Fig 2.4 (a) Pole Figures
Fig 2.4 (b) Pole figure without texture
16
Fig 2.4(c) Pole figure with texture
2.4.3. ORIENTATION DISTRIBUTION FUNCTION (ODF)
Pole figure representation of texture accounted for several limitations. During
projection of an orientation, certain orientations are missed as a 3D space is
represented in a 2D circle. It is necessary to analyze all orientations for complete
understanding of texture of the material. With the help of ODF, it is possible to describe
the complete texture information of a sample [14].If the orientation of a grain can be
represented by the parameter ‘g’. An ODF is a mathematical series expansion, for
which we will use the symbol ‘f’ that describes the volume fraction of grains in all
intervals g ± dg.
(dV/V) = f(g).dg
The integral of the ODF over all orientations should sum up to 1. ODF is used
statistically to make all possible orientation of grain where no loss of data occurs and
measurement of sample gives accurate results. The ODF of a sample without any
texture is a constant. If the sample possesses any texture, the ODF has maxima and
minima [16].
2.4.4. EULER ANGLES:
In order to give a graphical representation of an ODF, a method must be found to define
the orientation ‘g’ of a grain. This is made possible by the concept of ‘Euler angles’. In
this concept two different co-ordinate systems are defined. The first is connected to the
sample (sample axes system Xi) and the second to the crystal of a grain (crystal axes
system). Both systems are Cartesian and right handed. Fig 2.5 shows the orientation of
the crystal axis system and the sample axis system. The sample system is related to
the shape of the sample. For example, for a rolled sheet, the axis X 1 is taken in the RD,
X2 in the transverse and X3 in the ND of the sheet [14]. The orientation of the crystal
axes system can now be expressed in the reference frame of the sample axes system
by three rotations. These three rotations bring both systems together. In the literature,
several conventions have been proposed to perform these rotations. The most widely
used system is the system of Bunge where the rotation convention followed is ND-RDND. Figure 2.6 depicts the Bunge’s method of rotation.
17
c
Fig 2.5 Orientation of the crystal axis system {Xi } and the sample axis system {RD, TD, ND};
s is the intersection of the planes (RD–TD)and ([100]–[010])[17].
Fig 2.6 Definition of the Euler angles φ1, Φ, and φ2 in the Bunge convention [18]

.At first a rotation φ1 around ND is performed; which will bring RD in the positions, with s the
intersection of the planes (RD–TD) and ([100]–[010]). The attainment of new positions of RD
and TD are now RD’and TD’.

Then, a rotation of Φ around RD’; this will bring ND together with[001];TD’will now get the
position TD’.

Finally, a rotation of φ2 around the ND axis(which is now equal to[001]);due to this rotation,
RD’falls on[100]and TD’ comes together with[010].The angles(φ1, Φ, φ2) are called ‘Euler
angles’.
18
2.4.5. EULER SPACE
To represent every orientation in space it is important to represent it with the help of
three Euler angles or 2 Euler angles by keeping the other one constant. When three
Euler angles are used in 3D representation of texture data and when 2 Euler angles are
used by keeping other being constant, it is called 2D representation of texture data
which is normally used in real practice. When the three Euler angles are generally
plotted in Cartesian coordinate system, we get the so called ‘Euler space’ [14]. This
space is limited for φ1 and φ2 between 0° and 360°, and for φ between 0° and 180°
(Figure 2.7). Each crystal orientation can be represented in this Euler space. In this
representation, individual orientations will be found at several locations and at several
Euler angles of the Euler space.
Fig2.7 Graphical representation of crystallographic orientations with Euler angles [19].
19
2.4.6. TEXTURE DEVELOPMENTS IN CRNO SILICON STEELS
The magnetic properties of silicon steels such as magnetization curves,
permeability and core losses are correlated with metallographic properties like
microstructure and crystallographic texture [20], [21], [22]. The resulting properties of
materials
are
controlled
by
thermo-mechanical
processing
[20],[21],[22],[23],[24],[25],[26] which involves hot rolling, cold rolling and final
recrystallization annealing. The rolling temperature and the coiling condition showed
dependence on microstructure and texture evolutions during hot rolling [23],[24],[25].
This resulting texture is affected by the final properties of the cold rolled and
recrystallized sheets [27]. Hot rolling in the austenitic region results in development of a
final microstructure with a low magnetic induction quite contrary to hot rolling in the two
phase region which ensures good magnetic properties [28][29]. The amount of
deformation reduced and decrease in the hot rolling temperature typically induces
improved magnetic induction in non-oriented electrical steels [28]. In addition hot band
annealing results in enhanced permeability in silicon steels [30][31].
The various texture components that are observed in a non-oriented electrical
steels can be generally classified into 7 categories namely Goss {110} <100>, cube
{100} <001>, rotated cube {110} <110>, theta {100} <uvw>, eta {hkl} <100>, gamma
{111} <uvw> and alpha {hkl} <110> [30]. Among these 7, cube texture is most
desirable because {100} planes have greatest numbers of <100> axes. Texture with
{110} planes have relatively larger number of <100> and <110> axes which are also
desirable. On the other hand, the texture with {111} planes containing no <100> axes
and the texture with {112} planes including <111> axes are undesirable and should be
avoided for non-oriented steels. As a consequence, the ideal textures for non-oriented
electrical steels are in the sequence of: cube
{100}<001>, Goss {110} <100>, theta
{100} <uvw>, eta {hkl}<100>.[32]. The final texture developed in any non-oriented
steels is influenced by all the textures developed during every processing step i.e. hot
rolling texture, hot band annealing texture, recrystallization texture and texture during
grain growth which are described as follows:
In hot rolling the texture with low intensity of {110} <001> and {112} <111> are
found [33]. Hot rolling also gives rotated cube {110}<110> orientation which is
20
interesting for magnetic applications [34]. Hot-band annealing at a higher temperature
is very effective to obtain both high magnetic induction and low core loss which are
very essential, while it enhances the anisotropy of magnetic properties which is
detrimental for a motor or generator manufacture [35]. These effects of hot-band
annealing can be explained principally by the texture effect. The increase in planar
anisotropy by hot-band annealing may be closely related to an increase in the {110}
component and decreases in the {211} and {222} components.
Recrystallization
texture is one of the most important textures because the maximum texture property
variation occurs between cold rolling and annealing when new strain free grains are
induced from the strained lattice. The various texture components which are observed
during recrystallization are namely Goss {110}<100>, cube {100}<001> and gamma
fiber {111} <uvw> components [36]. The intensity of Goss component is strongest. The
general rule which governs texture development during grain growth in electrical steels
can be proposed as follows: for a texture component to be strengthened during grain
growth, the grains of specific orientations should have not only a size advantage over
other orientations but also a higher frequency of high angle, high energy grain
boundaries [37]. The texture of the final products is also greatly affected by the
microstructure prior to cold rolling, the quantity of inclusions and the reduction of cold
rolling. When a hot-rolled sheet is annealed to increase its grain size, the development
of recrystallized grains with {111} planes, from the original grain boundary, is
suppressed, whereas the development of recrystallized grains with {100} planes is
enhanced in cold-rolled and final-annealed products. Though, it requires more
production cost the two-stage cold rolling method also being practiced to get better
texture. In Figure 2.8 represents some of the important texture components at a
constant φ2.
21
Fig 2.8 Schematic representation of the most important texture components in the φ2=45°
section of ODF [38].
2.5. X-RAY DIFFRACTION
Texture is measured by X-ray diffraction. The XRD process is basically used to
observe the macro or bulk structure of a sample
2.5.1 FEATURES OF X-RAY DIFFRACTION METHOD
XRD method is featured by large penetration depth (5 μm) and a spatial resolution
ranging from 25 μm (with X-ray capillary optics) to 1 mm. Figure 2.9 shows the basic
method of X ray diffraction.
Advantages of using XRD

It provides well established technique.

Relatively a large area is scanned in one scan.
22

Quite a large number of grains (tens of thousands) can be studied in one
experiment.

Macroscopic samples is usually examined by XRD.
Limitations of using XRD

Calculations of orientation distribution function from pole figures is complex and
and may give wrong informations.

Poor spatial resolution – it is not suitable for microscopic samples which makes it
difficult to relate texture to microstructure.
X-Rays and Texture Analysis
•
Grains are visible under a microscope, but the orientation of the unit cells within
those grains cannot be observed.
•
X-Rays and electrons are basically diffracted from atomic planes.
•
Varied arrangement of planes (texture) shows differences in the various
diffraction patterns.
2.9 Basic method of X Ray Diffraction
23
CHAPTER 3:
MATERIALS AND EXPERIMENTAL PROCEDURE
3.1 MATERIALS
Hot rolled silicon steels of 2.3 mm thickness are subjected to cross-rolling at 10%
true strain of 0.5 mm thickness reduction in a laboratory rolling mill. The crossrolled samples are then subjected to annealing at 850°C for 1hr. the chemical
composition of the silicon steel is shown in table 3.1.
Table 3.1 The Chemical composition(in wt. %)of Silicon steel sample.
C
0.039
Si
P
S
Mn
Al
Fe
1.52
0.0216
0.02
0.35
0.0525
Balance
From cross-rolled and annealed silicon steel sheets, samples are prepared and
observed (1) in the rolling direction (2) 45˚ to the rolling direction (3) 90˚ to the rolling
direction for different characterization.
3.2. TEXTURE CHARACTERIZATION
The bulk texture characterization was performed by a Panalytical MRD X-ray diffraction
system at IIT Bombay and is used for the present study. Four different pole figures,
(100), (110), (111) and (112) were measured. Subsequently the ODF was estimated
using an academic software Labotex.
3.3. MAGNETIC PROPERTIES
The magnetic properties were measured by an equipment called PC based Pulse
Field Hysteresis Loop Tester. A software is used to interface the system to the PC and
the obtained datas are processed to calculate various hysteresis parameters like core
loss and permeability of the sample.[39]
24
CHAPTER 4:
RESULTS AND DISCUSSION
Figures 4.1, 4.2, 4.3 provides the ODF plot of the samples at the three direction i.e. 1)
the rolling direction, 2) 45° to the rolling direction, and 3) transverse direction
respectively. Volume fraction of important texture components i.e. Goss and cube
orientations is shown in figure 4.4. The figure clearly shows an insignificant variation of
Goss and cube in the samples.
Inferring from the observation it can be concluded that the texture development in the
three directions do not show any significant variation and thus, similar behavior is also
shown by the magnetic properties of the sample. However, magnetic permeability at 45
to the rolling direction is less in comparison to other two directions as shown in the
figure 4.6. The core loss though is similar in all the three directions as observed from
the figure 4.5.
From the above observations it is concluded that the cross rolling of the silicon steel
sample produced desired results with similar levels of core losses and insignificant
variation in magnetic permeability.
.
25
Figure 4.1 ODF plot, at constant 2, of silicon steel sample in the rolling direction.
26
Figure 4.2 ODF plot, at constant 2, of silicon steel sample in the direction 45o to the rolling direction.
27
Figure 4.3 ODF plot, at constant 2, of silicon steel sample in the transverse direction.
28
Figure 4.4 Volume fraction of cube, (001)<100> and goss, (110)<001> orientations at
directions of silicon steel sample.
29
different
Figure 4.5 Estimated core losses of silicon steel sample at different directions.
30
Figure4.6. Estimated permeabilities of silicon sample at different directions.
31
CHAPTER 5
SUMMARY
Texture and magnetic properties of the Silicon steel of 1.52% Si content was analyzed
and investigated at different directions, i.e., in the rolling direction, at 45° to the rolling
direction, in the transverse direction. From the results, the following conclusions are
made:
The volume fraction of the cube and Goss texture components are similar in all
the directions.
Magnetic permeability in the 45° direction is a little small in comparison to the
other two directions.
Core-loss observed in all the three directions are similar which show the ability of
silicon steels to be used in the electrical devices.
RECOMMENDATION
The present study is a preliminary study of texture and magnetic properties of silicon
steel which is done at basic laboratory scale .This is done by hot rolling the sample
followed by cross rolling. The permeability observed is similar in all the directions except
in 45° to the rolling directions. To achieve uniform properties in all the directions proper
annealing steps may be carried out (as performed industrially). Future studies can be
done by varying temperature of annealing for optimum properties of silicon steels.
32
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