Hva i himmelens navn er det som skal gjøres med disse?Blander de kobberet selv eller no?
De kan da ikke holde på med dette bare for moroskyld.Ingen forskning-ingen fremskritt.....
Ser bare på smelteverket her.Smelteprossess ,utstøyping teknikk,temperatur...etc.
Mye blir gjordt på en annen måte nå enn for 50 år siden,noe som har gitt flere og bedre kvaliteter
http://www.ysxbcn.com/upfile/soft/2010626/1998-2-20.pdf
Dislocation boundaries in drawn single crystal copper wires produced by Ohno continuous casting - Springer
http://www.ysxbcn.com/upfile/soft/20110126/23-p0152-20434.pdf
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wires produced by continuous casting
CHEN Jian
1, 2
, YAN Wen
1, 2
, LI Wei
3
, MIAO Jian
4
, FAN Xin-hui
2
1. Department of Applied Physics, Northwestern Polytechnical University, Xi’an 710072, China;
2. School of Materials Science and Chemical Engineering, Xi’an Technological University, Xi’an 710032, China;
3. Baoji Titanium Industry Co., Ltd., Baoji 721014, China;
4. School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Received 1 January 2010; accepted 14 April 2010
Abstract: The texture evolution of cold drawing copper wires produced by continuous casting was measured by X-ray
diffractometry and electron back-scatter diffractometry, and was simulated using Taylor model. The results show that in the drawn
poly-crystal copper wires produced by traditional continuous casting, 〈111〉 and 〈100〉 duplex fiber texture forms, and with increasing
strain, the intensities of 〈111〉 and 〈100〉 increase. In the drawn single-crystal copper wires produced by Ohno continuous casting,
〈100〉 rotates to 〈111〉, and there is inhomogeneous distribution of fiber texture along radial direction of the wires, which is caused by
the distribution of shear deformation. Compared with 〈100〉, 〈111〉 fiber texture is more stable in the drawn copper wires. Comparison
of the experimental results with the simulated results shows that the simulation by Taylor model can analyze the texture evolution of
drawn copper wires.
Key words: cold drawing; copper wires; texture; Taylor model
1 Introduction
During plastic deformation process, usually, crystal
rotation takes place and crystal defect forms, which
makes the change of microstructures and textures of
deformation metals. Actually, many researchers have
focused on the texture evolution during deformation
process, which is due to the following reasons: 1) The
deformation texture significantly affects the properties of
deformation metals; 2) The behavior of recovery and
recrystallization is closely connected with the
deformation texture; 3) Deformation mechanism can be
analyzed by the study of deformation texture.
With the development of information technology,
the demand of finer copper wires has kept rising.
Metallic wire drawing technology has advanced
possibility of manufacturing the fine wires with a
diameter less than 20 μm[1]. Therefore, texture evolution
of drawn copper wires has been widely investigated
using X-ray diffractometry (XRD), neutron
diffractometry or electron back-scatter diffractometry
(EBSD)[2−4]. It has been reported that the cold drawing
copper wires have typical textures consisting of a
majority 〈111〉 and a minority 〈100〉[2, 4]. ENGLISH and
CHIN[5] found that the relative intensity ratio of 〈111〉
and 〈100〉 fiber texture is different from one material to
others and depends on their stacking fault energy. The
texture evolution in drawn copper wires is affected by
the deformation temperature, and the intensity ratio of
〈100〉 to 〈111〉 is larger at −196, −77 or 100 °C than that
at 0 °C[6], which is due to the depletion of 〈111〉 by
twining at low temperature and by recrystallization at
high temperature. Although much work has been done on
fiber texture evolution of cold drawn copper wires, the
study object is the annealing copper wires and very little
work has been paid attention to the texture evolution of
the copper wires produced by continuous casting,
especially, the single crystal copper wires produced by
Ohno continuous casting (OCC)[7−10]. In the present
work, therefore, the texture evolution of cold drawn
copper wires produced by continuous casting was
Foundation item: Projects(50771076, 50901055) supported by the National Natural Science Foundation of China; Project(07JK274) supported by the
Education Department Foundation of Shaanxi Province, China
Corresponding author: YAN Wen; Tel: +86-29-83208009; E-mail:
yanwen@xatu.edu.cn
DOI: 10.1016/S1003-6326(11)60692-4 CHEN Jian, et al/Trans. Nonferrous Met. Soc. China 21(2011) 152−158 153
analyzed by XRD and EBSD, and simulated by Taylor
model.
2 Experimental
Polycrystal and single crystal copper wires with a
diameter of 8 mm were produced by use of traditional
continuous casting technique and OCC method,
respectively. During the cold drawn processing, the
deformed copper wires were not annealed, and to
eliminate the effect of drawn direction on the texture
evolution, the drawn directions were kept same in every
time of drawing. The true strain of drawn copper wires
can be calculated by following equation:
0 0
ln 2ln
A d
A d
ε = = (1)
where ε indicates true strain of the drawn wires; A0 and
d0 denote initial cross-section and diameter, respectively;
and A and d are those of the drawn wires. Texture
measurement of cold drawn polycrystal copper was
carried out on D/max-Ⅲ XRD and the samples for XRD
were cut according to Fig. 1. The texture of single crystal
copper was analyzed on a FEI Quanta−400F thermal
FEG scanning electron microscope with HKL Channel 5
system at 20 kV. Samples for EBSD were polished
mechanically, and then electropolished in a solution of
500 mL distilled water, 250 mL HPO3, 250 mL ethanol,
50 mL propanal and 5 g carbamide at 4 V and −15 °C for
4 min.
Fig.1 Sample for XRD analysis
3 Results and discussion
3.1 Copper wires without deformation
In traditional continuous casting technique, because
the heat flows from the center to the surface of the
copper wires, crystal nuclei, which form on the surface
of the wires due to cold mould, grow from the surface to
the center of the wires. Therefore, columnar crystal
perpendicular to axis direction of wires can be observed,
as shown in Fig.2(a). However, the temperature gradient
can be ignored in the center of wires, and then the grains
in the center are equiaxed, as shown in Fig.2(b). Fig.2(c)
shows {100} pole figure of polycrystalline copper wires
produced by traditional continuous casting technique,
indicating that the wires can be considered grains with
weak initial texture.
In OCC method[7], to prevent the nucleation of
crystals on the mould wall, a heated mould instead of the
conventional cold mould is used to maintain a certain
temperature. There is competitive growth of grains at the
initial solidification stage of OCC method, due to convex
solid/liquid interfaces. Competitive growth of grains
Fig.2 Microstructure and texture of copper wires produced by
traditional continuous casting technique: (a) Near surface;
(b) At center; (c) {100} pole figure (DD indicates drawing
direction and TD represents transverse direction)
means those grains with a high angle between 〈100〉 and
the direction of heat flow, the axial direction of the wires
will be swallowed by those with a low angle. Thus, the
axial direction of the single crystal copper wires
produced by OCC is always close to 〈100〉.
3.2 Texture evolution of drawn copper wires
Fig.3 shows the orientation map of single crystal
copper with different strains. In Fig.3, the crystal
directions indicated by color are parallel to the drawing
direction of the samples. From Fig.3, it can be found that
at a strain of 0.28, the orientation of drawn single crystal
copper referred to drawn direction does not change and is
still close to 〈100〉. At strains between 0.58 and 1.96,
although the axis direction of some regions in drawn
single crystal copper deviates from 〈100〉, 〈111〉 fiber
texture component cannot be observed. When the strain
is more than 1.96, 〈111〉 and 〈100〉 duplex fiber texture
forms, and with increasing strains, the intensity of 〈111〉
fiber texture increases. According to Figs.3(a)−(c), it can
be found that at low strains, besides of 〈100〉 fiber texture
〈112〉 can be observed, indicating that 〈100〉 rotates to
〈111〉 through 〈112〉. When strain is more than 2.77,
inhomogeneous distribution of fiber texture in the wires
appears. At a strain of 2.77, a large number of regions
with 〈111〉 fiber texture component are in the centre of
the wires. Increasing the strain to 4.12, 〈111〉 fiber
texture component spreads from the center to the surface
and the middle regions of deformed samples compared
with the specimens with a strain of 2.77.
Fig.4 shows the {100} pole figure of drawn
Fig.3 Orientation map for longitudinal section samples of
drawn 〈100〉 single crystal copper wires with strains of 0.28 (a),
0.58 (b), 0.94 (c), 1.96 (d), 2.77 (e) and 4.12 (f) referred to
drawing direction, and key (g)
polycrystalline copper wires with different strains. From
Fig.4, it can be found that the deformation textures of
drawn polycrystalline copper wires produced by
traditional continuous casting can be characterized as the
major 〈111〉 and minor 〈100〉 duplex fiber texture parallel
to drawn direction. When the true strain is low, 〈001〉 and
〈111〉 fiber texture components are diffused. With the
increase of true strain, the diffuse degree of 〈001〉 and
〈111〉 fiber texture components decreases.
In FCC metals with medium or high stacking fault
energy, many studies[11−14] have proved that the
deformation textures consisting of 〈111〉 and 〈100〉
duplex fiber texture parallel to drawing direction forms
during cold drawing process. Therefore, 〈111〉 and 〈100〉
Fig.4 {001} pole figures of drawn
polycrystalline copper wires with
different strains (DD indicates
drawing direction, and TD
represents transverse direction): (a)
0.58; (b) 0.94; (c) 1.39; (d) 2.77;
can be considered final stable fiber textures in drawn
FCC metals with medium or high stacking fault energy.
In the present work, for drawn polycrystalline copper
wires produced by traditional continuous casting, 〈111〉
and 〈100〉 duplex fiber textures can be observed at high
strains, which are consistent with the results of previous
studies[11−14]. When the initial orientation is one of
final stable fiber textures, for example, the initial
orientation of single crystal copper wires produced by
OCC is 〈100〉 parallel to drawing direction, the crystal
still is not stable, and 〈100〉 rotates to 〈111〉 through 〈112〉.
At high strains, 〈111〉 and 〈100〉 duplex fiber textures
form. In addition, at high strains, 〈111〉 fiber texture
spreads from the center to the surface of the wires with
increasing strain in drawn single crystal copper with
initial orientation 〈100〉 parallel to drawing direction,
indicating that there is inhomogeneous distribution of
fiber texture, which should be resulted from
inhomogeneous distribution of shear strain. CHO et al[15]
proposed by finite element analysis that there is a
variation of shear strain with radial position, which
comes from geometry deformation and friction effect,
and the shear strain increases with the increase distance
from the center of the wires. The spread of 〈111〉 fiber
texture from the center to the surface with increasing
strain in drawn 〈100〉 single crystal copper indicates that
shear deformation is not beneficial to the formation of
〈111〉 fiber texture parallel to drawn direction.
4 Simulation of cold drawn texture
In the present work, Taylor model[16] is used to
simulate the texture evolution during cold drawing
process. In Taylor model, it is considered that each grain
is with same strain. During cold drawing process, the
strain tensor Lij
′ in sample reference frame can be
expressed as[17]
0 0
0 2 0
0 0 2
ij
ε
ε
ε
⎧ ⎫
⎪ ⎪
′ = − ⎨ ⎬
⎪ ⎪
⎩ ⎭ −
L (2)
where ε=2lnR/R′. R and R′ indicate the diameters of
before and after deformation wires.
The strain tensor Lij
in crystal reference frame can
be expressed as
k
ij ij k ij
k
L m = + ∑ γ Ω (3)
where γk
is the shear rate for k slipping system;Ωij
is the
rotation tensor of the deformation crystal; mij=b
k
×n
k
, and
b
k
and n
k
are the normalization vectors of the slipping
direction and the normal direction of slipping plane for k
slipping system, respectively.
During deformation process, the strain tensor Lij
can
also be expressed as[18]
s a
Lij ij ij
= + D D (4)
s T
1
1 1
( ) ( )
2 2
m
k k k k
ij ij ij k
k
γ
=
D = + = + L L b n n b ∑ (5)
a T
1
1 1
( ) ( )
2 2
m
k k k k
ij ij ij k ij
k
γ
=
D L L b n n b = − = − + ∑ Ω (6)
In Eqs.(4)−(6),
s
Dij
and
a
Dij
are symmetrical strain
tensor and asymmetry strain tensor, respectively.
In order to simulate the texture evolution, the
rotation tensor Ωij
must be obtained from Eq.(6). The
relationship between the strain tensor Lij
in crystal
reference frame and the strain tensor Lij
′ in sample
reference frame is
t
ij ij
L = T L T′ (7)
Lij
′ can be obtained from Eq.(7); T is orientation matrix
of crystals before deformation.
u r h
v s k
w t l
⎧ ⎫
⎪ ⎪
= ⎨ ⎬
⎪ ⎪
⎩ ⎭
T (
where {hkl} is perpendicular to the normal direction of
analyzed planes; 〈uvw〉 is parallel to drawing direction
and [rst]=[hkl]×[uvw]. Therefore, the strain tensor Lij
in
crystal reference frame and the shear rate
k
γ can be
obtained from Eqs.(7) and (5), respectively. If Lij
, γk
, b
k
n
k
and n
k
b
k
are substituted into Eq.(6), the value of Ωij
will
be known. Then, the orientation matrix of crystals after
deformation can be calculated from the following
equation[19]:
( )
ij
F = −I Ω T (9)
where I is the unit matrix.
According to above method, the texture evolution of
copper wires produced by OCC method and traditional
continuous casting can be simulated. During simulating
process, the wires produced by traditional continuous
casting and OCC method are considered grains without
any initial texture and with 〈100〉 parallel to drawing
direction, respectively. Fig.5 shows {100} pole figures of
drawn polycrystalline copper wires with different strains.
From Fig.5, it can be found that after cold drawing
deformation, 〈111〉 and 〈100〉 duplex fiber texture forms
in polycrystalline copper wires without any initial texture.
With increasing strain the intensities of 〈111〉 and 〈100〉
Fig.5 {001} pole figures of cold drawn polycrystalline copper wires simulated by Taylor model: (a) 0.28;(b) 0.58; (c) 0.94; (d) 1.39;
(e) 2.77; (f) 4.12
increase. Comparison of the results in Fig.2 and Fig.4
with the results in Fig.5 shows that although there is little
difference between initial orientation of measured copper
wires and that of simulation metals, i.e. the measured
copper wires have a weak preferred orientation and
simulation metals are without any initial texture. The
simulation results of drawn copper wires are very similar
to the measured those of drawn polycrystalline copper
wires, especially at high true strains, indicating that the
effect of initial crystal orientation of drawn
polycrystalline copper wires on final drawn texture can
be ignored.
Fig.6 shows {100} pole figures of cold drawn
copper wires with initial orientation 〈100〉 parallel to
drawing direction. From Fig.6, it can be seen that 〈111〉
and 〈100〉 duplex fiber texture forms in the drawn copper
wires with initial orientation 〈100〉 parallel to drawn
direction and 〈100〉 rotates to 〈111〉, which is agreement
with the experimental results of drawn copper wires
produced by OCC method (see Fig.3). However,
comparison of the results in Fig.6 with those in Fig.3
shows that there is a difference between the texture
evolution simulated by Taylor model and that measured
by EBSD. For example, in the results simulated by
Taylor model (see Fig.6), at a strain of 0.28, the rotation
degree of crystal is great. In contrast, for single crystal
copper wires produced by OCC method, at a strain of
0.28, the orientation of drawn single crystal copper
referred to drawn direction does not change and is still
close to 〈100〉 (see Fig.3). Actually, the simulated wires
without deformation are considered 〈100〉 parallel to
drawing direction, but other crystal directions are not
determined. Then, they still are poly-crystal, as shown in
Fig.6(a). The wires produced by OCC method are single
crystal and 〈100〉 is parallel to drawing direction, as
shown in Fig.3(a). Thus, there is a difference of grain
size between the wires simulated by Taylor model and
measured by EBSD, indicating that the grain size affects
texture evolution of cold drawn copper wires. In addition,
previous studies[2−4] have proved that 〈111〉 and 〈100〉
are final stable fiber texture in FCC metals with medium
or high stacking fault energy. In the present work, the
results measured by EBSD and simulated by Taylor
model show that 〈100〉 rotates to 〈111〉 in copper wires
with initial orientation 〈100〉 parallel to drawing direction,
and the intensity of 〈111〉 is more than that of 〈100〉 in
drawn polycrystalline copper wires with high strains,
indicating that compared with 〈100〉, 〈111〉 fiber texture
parallel to drawn direction is more stable in drawn
copper wires.
Fig.6 {100} pole figures of cold drawn copper wires with 〈001〉 initial orientation simulated by Taylor model: (a) Without
deformation; (b) 0.28; (c) 0.58; (d) 1.96; (e) 2.77; (f) 4.12
5 Conclusions
1) In drawn polycrystal copper wires produced by
traditional continuous casting, 〈111〉 and 〈100〉 duplex
fiber texture forms, and with increasing strains, the
intensities of 〈111〉 and 〈100〉 increase.
2) In drawn single-crystal copper wires with initial
orientation 〈100〉 parallel to drawing direction, 〈100〉
rotates to 〈111〉, and 〈111〉 and 〈100〉 duplex fiber texture
forms at high stains. Compared with 〈100〉, 〈111〉 fiber
texture is more stable in drawn copper wires.
3) Inhomogeneous distribution of fiber texture in
drawn single-crystal copper wires along radial direction
is caused by the distribution of shear deformation.
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