IRON-NICKEL ALLOY HAVING SPECIAL SOFT MAGNETIC PROPERTIES

ALLIAGE FER-NICKEL A PROPRIETES MAGNETIQUES SPECIALES DE FAIBLE INTENSITE

English Abstract

The invention relates to a soft magnetic iron-nickel material containing 46-49% nickel, the residue being substantially iron. The characterizing feature of the invention is that after a heat treatment on a strip sample 0.20 mm in thickness, the iron-nickel material has a texture distribution in which of measured (111) polar figures the relative proportions of the texture components having the Euler angles (?1, .PHI., ?2) = (0, 0, 0) are 20 to 50% and (?1, .PHI., ?2) = (26, 45, 30) are 10 to 40%, or having the Euler angles (?1, .PHI., ?2) = (0, 0, 0) are 10 to 40%, (?1, .PHI., ?2) = (26, 45, 30) are 5 to 25% and (?1, .PHI., ?2) = (30, 35, 35) are 10 to 25%.

French Abstract

L'invention porte sur un matériau fer-nickel à propriétés magnétiques de faible intensité contenant 46 à 49 % de nickel, le reste étant essentiellement du fer. L'invention est caractérisée en ce qu'après un traitement thermique sur une bande d'échantillonnage ayant une épaisseur de 0,20 mm, le matériau fer-nickel a une distribution de texture dans laquelle une polaire (111) mesurée représente les proportions relatives des composantes de texture dont les angles d'Euler (?1, .PHI., ?2) = (0, 0, 0) sont compris entre 20 et 50 % et (?1, .PHI., ?2) = (26, 45, 30) entre 10 et 40 %, ou dont les angles d'Euler (?1, .PHI., ?2) = (0, 0, 0) sont compris entre 10 et 40 %, (?1, .PHI., ?2) = (26, 45, 30) entre 5 et 25 % et (?1, .PHI., ?2) = (30, 35, 35) entre 10 et 25 %.

Claims

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A heat treated iron-nickel soft magnetic material
consisting of 46-49% by weight nickel and the balance of
substantially iron, which, when a strip sample 0.20 mm in
thickness thereof is measured, has a texture distribution in
which of measured {111} polar figures, relative proportions of
texture components having the Euler angles (~1, .PHI., ~2) - (0,
0, 0) and (~1, .PHI., ~2) - (26, 45, 30) are 20 to 50% and 10 to
40%, respectively.
2. A heat treated iron-nickel soft magnetic material
consisting of 46-49% by weight nickel and the balance of
substantially iron, which, when a strip sample 0.20 mm in
thickness thereof is measured, has a texture distribution in
which of measured {111} polar figures, relative proportions of
texture components having the Euler angles (~1, .PHI., ~2) - (0,
0, 0), (~1, .PHI., ~2) - (26, 45, 30) and (~1, .PHI., ~2) = (30, 35,
35) are 10 to 40%, 5 to 25% and 10 to 25%, respectively.
3. A heat treated iron-nickel soft magnetic material
according to claim 1, which contains 0.53 wt.% Mn, 0.27 wt.%
Si, 0.30 wt.% Mo and less than 0.5 wt.% of total impurities
due to melting in addition to nickel and iron.
4. A heat treated iron-nickel soft magnetic material
according to claim 2, which contains 0.41 wt.% Mn, 0.23 wt.%

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Si, 0.06 wt.% Mo and less than 0.5 wt.% of total impurities
due to melting in addition to nickel and iron.
5. A heat treated iron-nickel soft magnetic material
according to claim 1 or 3, which is obtainable by final heat
treatment at 1080° C for a holding time of 4 hours.
6. A heat treated iron-nickel soft magnetic material
according to claim 2 or 4, which is obtainable by final heat
treatment conducted at 1060°C for a dwell time of 20 minutes.
7. A heat treated iron-nickel soft magnetic material
according to claims 1, 3 or 5, which, with magnetic field
strengths H of 120 mA/cm or higher, has a magnetic flux
density B of at least 1100 mT, as measured following a slight
annealing treatment on core sheet packs of strip thickness
0.20 mm at a frequency of 50 Hz.
8. A heat treated iron-nickel soft magnetic material
according to claim 2, 4 or 6, which is obtainable by final
heat treatment at 1080°C for a holding time of 4 hours.
9. A heat treated iron-nickel soft magnetic material
according to claim 7, wherein the magnetic flux density B is
1100 - 1300 mT.

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10. A heat treated iron-nickel soft magnetic material
according to claim 8, wherein the magnetic flux density B is
1100 - 1300 mT.
11. A heat treated iron-nickel soft magnetic material
according to any one of claims 1 to 10, which has an initial
permeability µ4 of 6,000 to 14,000 as measured at a field
strength ~ of 4 mA/cm using the strip sample 0.20 mm in
thickness.

Description

2152633
RON-NICKEL ALLOY HAVING SPECIAL SOFT MAGNETIC PROPERTIES
The invention relates to a material of an iron-nickel alloy
containing 46-49o nickel and having special soft
magnetic properties which are achieved by the adjustment of a
structure having a predetermined texture distribution following a
heat treatment.
It is known that certain magnetic properties can be achieved or
positively influenced in iron-nickel alloys having nickel
contents between approximately 40 and 65% by the adjustment of
textures having a preferred direction <100> in the rolling
direction, such as the cubic texture or the (210)<001> texture
(F.Pfeifer, Structure of Metals, Deutsche Gesellschaft fur
Metallkunde e.V., Oberursel (1981), pages 293 et seq.). This is
possible because in iron-nickel alloys having medium nickel
contents the cube edge <100> of the cubically face-centred
lattice is the magnetic preferred direction.
Ranges for the cubic texture (100)<001> and for the (210)<001>
texture are determined by the final degree of deformation and the
intermediate annealing temperature and also the grain size
achieved thereby prior to the last cold shaping, after the final
annealing treatment. This dependence of the structure is shown
diagrammatically in Fig. 1(a) and (b).
At first with final degrees of deformation up to approximately
80% after the final annealing treatment, a fine-grained isotropic
grain structure is formed by primary recrystallization, the grain
21421-266

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size generally increasing with increasing final annealing
temperature and increasing final degree of deformation. With
final degrees of deformation greater than 80% and, on condition
that the final annealing temperature is not too high -
approximately between 900 and 1050~C - and the holding times are
not too long, the cubic texture (100)<001> is formed, whose
sharpness increases with increasing final degree of deformation
and decreasing intermediate annealing temperature. On a certain
fairly high final annealing temperature of approximately 1080°C
onwards, with a long enough dwell time at that temperature
secondary recrystallization sets in and destroys the cubic layer.
The final annealing temperature at which the secondary
recrystallization begins depends inter alia on impurities and
additives with affinity to oxygen. In general these increase the
necessary final annealing temperature. This also affects the
range of the final degree of deformation and the intermediate
annealing temperature at which secondary recrystallization can
take place. This range of suitable intermediate annealing
temperatures and degrees of deformation corresponds to that of
the cubic texture, since this is a precondition for secondary
recrystallization. Over a certain narrowed-down range, due to
growth selection during secondary recrystallization preferably
grains having the orientation (210)<001> are formed. With higher
degrees of deformation, coarse grain is formed.
Table 1 shows characteristic magnetic properties for prior art
materials having a nickel content of approximately 48o with the
aforedescribed structures, in comparison with the material
according to the invention for the strip thickness 0.20 mm.

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Table 1
Structure x.41) (Ei = 4 mA/cm)H (H = 200
mA/cm) in mT2)
fine-grained, isotropic 6000 - 12000 approx. 1050
prior art materials
secondarily 12000 - 20000 approx. 1080
recrystallized
material according to 6000 - 14000 approx. 1100 -
the invention 1300
1) Level of initial permeability ~4, depends on the level of
the final annealing temperature and the duration of the dwell
time during the final annealing treatment.
2) Magnetic values are measured at 50 Hz.
In comparison with prior art materials, more
particularly with fairly high field strengths - for example,
H = 120 mA/cm or higher, especially, 200 mA/cm -, the material
according to the invention achieves substantially higher
values for the flux density B i.e., at least 1100 mT,
accompanied by still relatively high initial permeabilities.
These values are achieved by a purposeful production method; a
particular distribution of
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252833
textural components is adjusted in the primary structure by a
predetermined final degree of deformation and a predetermined
intermediate annealing temperature after a final heat treatment
with strip thickness 0.20 mm.
Using measured {111} polar figures, the material according to the
invention is characterized by stating the relative proportion for
each textural component, each of which is described by the Euler
angle (cpl, ~, cp2) (Table 2) .
Table 2 discloses the relative proportion M for each
textural component, each described by the Euler angles
(~pl, ~, ~2), determined for measured ~111~ polar figures
on differently heattreated samples of strip thickness
0.20 mm, whereby the material according to the invention
is characterized by two textural distributions A and B.
The three Euler angles as defined in G. Goltstein
"Rekristallisation metallischer Werkstoffe", 1984, ed.:
Deutsche Gesellschaft fur Metallkunde e.V., give a
determined sequence of three rotation angles, which
transfer the sample-solid system of coordinates to the
crystal-solid one.
Table
B
Characterization
textural components cpl ~ ~p2 M / % cpl ~ ~p2 M /
0 0 0 20-50 0 0 0 10-40
26 45 30 10-40 26 45 30 5-25
30 35 35 10-25
21421-266

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215263
The material according to the invention is characterized in that
after a heat treatment on a sample or strip thickness 0.20 mm the
relative proportions of the textural components having the Euler
angles (~pl, ~, cp2) - (0, 0, 0) and (cpl, ~, ~p2) - (26, 45, 30) are
20 to 50% and 10 to 40% respectively (characterization A). This
textural distribution can be achieved with a heat treatment of,
for example, 1080°C and a holding time of 4 hours, based on a
fairly long steady annealing.
As Fig. 2 makes clear, the material according to the invention
has advantages, since even the high values for the flux density B
with medium and fairly high field strengths are reached even with
relatively low final annealing temperatures and relatively short
annealing times, since in this case secondary recrystallization
is not a necessary precondition for the good magnetic properties
described. In this case - i.e., after a heat treatment, based on
a brief continuous annealing, on a sample of strip thickness
0.20 mm the material according to the invention is characterized
in that the relative proportions of the textural components
having the Euler angles (cpl, ~, cp2) - (0, 0, 0), (~1, ~, cp2) -
(26, 45, 30) and (~pl, ~, cp2) - (30, 35, 35) are 10 to 400, 5 to
25% and 10 to 25% respectively (characterization B). This
textural distribution can be achieved, for example, by a heat
treatment of 1060°C and a dwell time of 20 minutes on a strip
sample of thickness 0.20 mm.

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The material according to the invention, whose chemical
composition is shown in Table 3, is suitable more particularly
for brief heat treatments in continuous furnaces at relatively
low temperatures. Moreover, the material according to the
invention has the maximum saturation flux density for iron-nickel
alloys of approximately 1.55 T.
Table 3
by weight)
W1 W2
Cr 0.05 0.03
Ni. 47.65 47.60
Mn 0.52 0.41
Si 0.27 0.23
Mo 0.30 0.06
Ti 0.01 0.01
Nb 0.01 0.01
Cu 0.05 0.05
Fe 51.05 51.50
S 0.002 0.002
P 0.002 0.002
A1 0.005 0.005
Mg 0.001 0.001
Pb 0.001 0.001
Sn 0.01 0.01
Co 0.05 0.05
C 0.016 0.007

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The majority of the elements listed in Table 3 in the range up to
0.1% are usual admixtures due to melting. Their total content
should be below 0.5%. The elements with more than 0.1% - i.e.,
Mn, Si, Mo - should be limited to max. 0.1% Mn, max. 0.5% Si,
max. 1% Mo.

Representative Drawing