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1. The Influence of Texture on the
Magnetic Properties
 Behzad Sadeghi
 PhD Student in Nanotechnology Engineering

2.  Introduction to Magnetic properties & Electrical Steel.
 Texture evolution during cold work and recrystallization.
 Effect of metallurgical factors on the magnetic
properties.
grain size
annealing temperature
chemical composition
Heating Rate
annealing time
frequency
 Effect of Crystallographic Texture on Magnetic
Characteristics of Cobalt Nanowires.
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 Soft magnetic materials are:
energy losses must be low ; one familiar example
consists of transformer cores.
 A soft magnetic material must have a high
initial permeability and a low Hc.
 One alloy commonly used for this application
is the Fe–3%Si alloy( Electrical Steel)
 Hard Magnetic Materials:
 High resistance to demagnetization
 High Mr ,Hc, as well as a low initial
permeability, and high hysteresis energy losses

4.  Iron Alloy with Si(0-6.5%); BCC
 Manufactured in the form of cold-rolled strips
 Depending on the requirement of magnetic properties
 Grain oriented electrical steel (GOES)
 Non-grain oriented electrical steel (NOES)
 Desirable Properties of ES:
• High magnetic induction (Magnetic flux Density) (Permeability)
• Low core energy loss
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 Core loss (or iron loss/watt loss) is divided into two
components;
 Hysteresis loss
 Eddy current loss.
 However, effect of metallurgical factors on these two
components does not always follow similar trends and very
often an optimum value of these metallurgical variables
(e.g. grain size) is required to achieve best magnetic
properties in Electrical Steel.
Texture effects on magnetic properties in high-alloys NOES, S. K.Chang, J. Metal Science and HeatTreatment,2007

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Easy axis of magnetization

6.  In Si non-oriented steel, Core loss is found to be the lowest for (100)
planes and highest for (111) planes,
 Thus,the (100)〈uvw〉 or cube fiber texture is the most suitable one and
(111) 〈uvw〉 or gamma fiber is one of the worst one for non-oriented
electrical steels.
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One of the most effective stages for modify of the texture:
Annealing
Nucleation {110} <001> (Goss) grains mainly within
shear bands
These bands were often found in the coarse grains
specimens
Annealing cause coarsening the microstructure
Chemistry
Grain size
Crystallographic Texture
Stress states
Magnetic Properties
(Core loss and the Permeability)
Effect of initial grain size on texture evolution and magnetic properties in NOES,J.T Park et al, J.Magnetism and Magnetic Materials,2009
Magnetic Induction (B) increase with increasing R (Size grain) in
the irreversible magnetization range (H¼80–200 A/m), whereas it
decreases with increasing R in the rotation magnetization range (H
>300 A/m).
So, there is an optimal grain size

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 The Goss and the Cube components that have favorable magnetic
properties.
The orientation of recrystallized grains at the early stage of
recrystallization is maintained up to the late stage of recrystallization
without any significant change
T=790 C T=950 C
Strength Decrease
Effect of initial grain size on texture evolution and magnetic properties in NOES,J.T Park et al, J.Magnetism and Magnetic Materials,2009
Partial α-fiber from {001} <110>
to {111} <110> +
Complete γ-fiber {111} <110>
and {111} <112>
Weaker {001} <110>,{111} <110>
+
Stronger {111} <112> component
and {111} <112>

8. 8Texture effects on magnetic properties in high-alloys NOES, S. K.Chang, J. Metal Science and HeatTreatment,2007
The coarse-grained specimens have weaker <112> and <110> at the
same temperature than the fine-grained specimens.
 Increasing grain size lowers the core loss in non oriented electrical steels because
it reduces the area of grain boundaries which restrain the movement and rotation
of magnetic domains during magnetization
Grain-size has an opposite effect on the hysteresis and eddy current
losses, thus there is an optimal grain size, which can help minimize
the sum of hysteresis and eddy current losses (core loss)
ON THE CONTRARY
 Eddy current loss ά D 0.5
 Magnetic domain size increases with increasing grain size(D).
 Hysteresis loss ά the nucleation and annihilation of domains. hysteresis
loss ά 1/d
 D = grain boundary = barrier to domain wall motion = Hysteresis
loss

9. 9Texture effects on magnetic properties in high-alloys NOES, S. K.Chang, J. Metal Science and HeatTreatment,2007
Ingots were hot-rolled to a thickness of 2.6 mm, then cold-rolled to 0.35
mm, and annealed at 1000 C for 2 min in an oxidation-free atmosphere

10. 10Texture effects on magnetic properties in high-alloys NOES, S. K.Chang, J. Metal Science and HeatTreatment,2007
Higher than in steels bearing Co and Mo
Lower than in steels bearing Co and Mo
The texture factor was introduced to estimate the effect of
favorable and unfavorable texture
Co and Mo form carbides and thus presumably hinder the development of
cubic and Goss textures but Ni does not form carbides thus does not hinder
magnetization

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 Magnetic induction and core loss are directly related to the texture factor
 The introduction of Co, Mo, or Ni clearly decreases the relation of the
texture factor to magnetic properties.
Texture effects on magnetic properties in high-alloys NOES, S. K.Chang, J. Metal Science and HeatTreatment,2007
Larger grains provide larger misorientation angles
Ni-bearing steel has a low fraction of grains with small-angle
boundaries + higher fraction of grains with large-angle boundaries

12. 12Rapid heating effects on grain-size, texture and magnetic properties of 3% Si NOES, J.Wang et al, J. Bull. Mater. Sci, 2011
Heating
Rate
Recovery
Stored
Energy
Nucleation
& Growth
Rate
Smaller
Grain Size

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 Recrystallized texture depends on the nucleation and growth rates of
different orientations
 Recrystallization nuclei mainly concentrate on the regions with high stored
energy, generally, the {110} and {111} texture components.
The recrystallized texture components is γ-fiber and the preferred orientations
mostly concentrated along the {111} <110> and {111} <112 > directions.
High heating rate = reduce stored elastic energy recovery = increase the
driving force nucleation & coarsening =promote high angle grain boundaries
migration = decreases the <111>//ND intensity and increases the intensity
of the {110}<001> Goss texture component.
Rapid heating effects on grain-size, texture and magnetic properties of 3% Si NOES, J.Wang et al, J. Bull. Mater. Sci, 2011

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There are No easy magnetic directions in the {111} planes, and the
{110}<001> (Goss) orientation has <100> easy magnetization direction
along the rolling direction
Texture optimization of nonoriented electrical steels mainly consists of
avoiding the occurrence of grains with <111>//ND fiber and generating
more grains with <001>//RD and <001>//ND fibers.
rapid annealing is favorable to reduce the γ-fiber intensity
and increase the Goss texture component
Thus
Rapid heating effects on grain-size, texture and magnetic properties of 3% Si NOES, J.Wang et al, J. Bull. Mater. Sci, 2011

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The intensity of all texture components changes slightly.
With a high heating rate, the annealing time could decrease the intensity of
the recrystallized texture, including both the favorable Goss component
{110}<001> and unfavorable {111}<112> and {111}<110> texture components.
The decrease in intensity of the Goss {110}<001> component is less than that
of the {111}<112> and {111}<110> components.
RapidAnnealing Effects on Microstructure,Texture, and Magnetic Properties of NOES, J.Wang et al, J. Met. Mater. Int,2011
(a) 3 s
(b) 6 s
(c) 9 s
(d) 30 s

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This is due to magnetic induction so the intensities of the {111}<112> and
{554}<225> texture components are similar for both 15- and 30-second holding times
,but the intensity of the Goss component is higher at 15 seconds than at 30 seconds.
Core loss decreases with holding time due to the larger mean grain size, which
decreases magnetic hysteresis losses.
There are appropriate annealing time (6 to 9 seconds)
ranges at a high heating rate of 300 C/s, which
simultaneously can optimize the core loss and magnetic
induction.
RapidAnnealing Effects on Microstructure,Texture, and Magnetic Properties of NOES, J.Wang et al, J. Met. Mater. Int,2011

17. 17Effect of metallurgical factors on the bulk magnetic properties on NOES, P. Ghosh et al, J. Magnetism and Magnetic Materials,2014

18. 18Effect of metallurgical factors on the bulk magnetic properties on NOES, P. Ghosh et al, J. Magnetism and Magnetic Materials,2014
 B1 and B3 steels in non-SRA condition
showed two weak fiber components, one
along gamma fiber and the other parallel to
α-fiber (RD [110]).
 SRA treatment not only improved the
overall ODF intensity in these cases but
also improved the cube fiber intensity
In case of C3, the overall intensity of
ODF increased almost by double (just like
B1 and B3) but for C4 no significance
enhancement of ODF intensity was
observed after SRA.
SRA resulted in an improvement in the
cube fiber intensity for C3 and gamma
fiber intensity did not get affected by SRA
for C3

19. 19Effect of metallurgical factors on the bulk magnetic properties on NOES, P. Ghosh et al, J. Magnetism and Magnetic Materials,2014
Increasing Si content and decreasing
grain size help to reduce eddy current loss
and in turn decreases overall core loss at
high frequencies.
Higher the carbon content, larger is the
probability of formation of small Fe3C
particles which act as pinning sites and
obstruct domain wall motion during
magnetization process

20. 20Effect of CrystallographicTexture on Magnetic Characteristics of Cobalt Nanowires, K. Maaz et al, J. Nanoscale Res Lett. 2010
XRD studies of the samples reveal
that 70-nm-diameter wires are
strongly [002] textured, however,
with increasing diameter, [100] and
[101] textures also become strong.
TC values larger than 1 indicate a preferred orientation of the crystals/grains
in the samples.
The cobalt nanowires of 70 nm diameter are strongly [002] textured.
 Distinguishing between Local PH and Solution PH.
 This difference increases as the pore diameter decreases.
 Pores with large diameters lead to high current density
during electrodeposition.
smaller ad-atom mobility and thus a less distinct wire texture

21. 21Effect of CrystallographicTexture on Magnetic Characteristics of Cobalt Nanowires, K. Maaz et al, J. Nanoscale Res Lett. 2010
Coercivity of the nanowires along the
wire long axis decreases with increasing
diameter most probably due to the effect
of decreasing [002] texture
The coercivity increase with increasing
diameter due the increasing [100] and [101]
textures and then decreases for 120 nm wire
due the dominant role of domain
transformation (from single to multi
domain) in thicker wires.
Parallel directionPerpendicular direction

22. The specimens having different initial grain sizes have significantly different
textures in the cold-rolled state and the annealed state.
During the recrystallization stage, new grains formed in the coarse-grained
specimens have stronger Goss but weaker γ-fibre texture
The magnetic induction of the coarse-grained specimens is always higher at
the same temperature than that of the fine grained specimens
The core loss of the coarse-grained specimens is lower at the same
temperature than that of fine-grained specimens
Recrystallized grains could be refined due to the high recrystallization
nucleation rates caused by higher heating rates.
There are appropriate annealing temperatures and annealing time (6 to 9
seconds) ranges at a high heating rate, which simultaneously can optimize the
core loss and magnetic induction.

23.  Increasing Si content of these steels has the similar consequence like
decreasing grain size at higher frequency.
 It seems that the effect of metallurgical variables on core loss comparatively
straight forward than permeability in NOES
 The recrystallization texture of non-oriented electrical steels could be greatly
optimized by increasing the heating rate, which reduces the fraction of
<111>//ND γ-fiber and increases the fraction of the {110}<100> Goss
component.
 In case of parallel applied field, the coercivity has been found to be
decreasing with increasing diameter of the wires while in perpendicular
case; the coercivity observes lower values for larger diameter..
.

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