IRON-NICKEL-COBALT ALLOY

ALLIAGE FER-NICKEL-COBALT

English Abstract

Use of an iron-nickel-cobalt alloy in CFC mould
construction comprising (in % by mass) Ni from 30 to 35%, Co
from 3 to 6%, Al from 0.001 to 0.1%, Mn from 0.005 to 0.5%,
Si from 0.005 to 0.5%, C max. 0.1%, balance Fe and
constituents resulting from production, with the alloy
having a mean coefficient of thermal expansion in the
temperature range from 20 to 200°C of < 2.0 x 10 -6/K.

French Abstract

L'invention concerne l'utilisation d'un alliage fer-nickel-cobalt pour un élément de construction en CFK comprenant (en % en masse) de 30 à 35 % de Ni, de 3 à 6 % de Co, de 0,001 à 0,1 % de Al, de 0,005 à 0,5 % de Mn, de 0,005 à 0,5 % de Si, jusqu'à 0,1 % de C, le reste étant du fer et d'inévitables impuretés, ledit alliage présentant dans la zone de températures comprise entre 20 et 200 °C un coefficient d'expansion thermique moyen < 2,0 x 10-6/K.

Claims

CLAIMS:
1. Use of an iron-nickel-cobalt alloy in a carbon fiber-reinforced composite
(CFC) mold having in % by weight:
Ni 32.5 to 34.5%
Co >3.0 to 5.5%
Al 0.001 to 0.1%
Mn 0.005 to 0.1%
Si 0.005 to 0.1 %
C 0.005 to 0.05%
wherein the alloy contains the following maximum contents of
accompanying elements:
Cr max. 0.1 %
Mo max. 0.1%
Cu max. 0.1%
Ti max. 0.1 %
Mg max. 0.005%
B max. 0.005%
N max. 0.006%
O max. 0.003%
S max. 0.005%
7

P max. 0.008%
Ca max. 0.005%
Zr max. 0.05%
remainder Fe and constituents resulting from the production process,
the alloy having a mean thermal expansion coefficient of <1.5 x 10 -6/K
in the temperature range from 20 to 200°C.
2. The use in accordance with claim 1, wherein the alloy has the following
composition in % by weight:
Ni 32.5 to 33.5%
Co > 3.5 to < 4.5%
Mo max. 0.05%
Cr max. 0.05%
C max. 0.009%
Mn max. 0.04%
Si max. 0.03%
S max. 0.003%
N max. 0.004%
Ti max. 0.01 %
Cu max. 0.05%
P max. 0.005%
8

Al 0,001 to 0.05%
Mg max. 0.0008%
Ca max. 0.003%
Zr max. 0.03%
O max. 0.003%
remainder Fe and constituents resulting from the production process,
the alloy having a mean thermal expansion coefficient of <1.3 x 10 -6/K
in the temperature range from 20 to 200°C.
:3. The use in accordance with claim 1 or 2, wherein the alloy further
contains 0.001 to 0.1 weight % Nb.
4. The use in accordance with any one of claims 1 to 3, for a large-format
semi-finished product which is a sheet material, strip material or tube
material.
5. The use in accordance with any one of claims 1 to 3, for a wire.
6. The use in accordance with claim 5, wherein the wire is an added
welding substance.
7. The use in accordance with any one of claims 1 to 3, for a molded
component for producing an aircraft part from a carbon fiber-reinforced
composite.
8. The use in accordance with any one of claims 1 to 3, for a forged part.
9. The use in accordance with any one of claims 1 to 3, for a cast
component.
9

Description

CA 02637499 2011-09-01
29779-28
Iron-Nickel-Cobalt Alloy
The invention relates to the use of an iron-nickel-cobalt alloy.
Increasingly, components are being produced from carbon fiber-reinforced
composites (CFC),
even those for products with safety considerations, such as in aircraft
manufacture. For
producing such components, implements (molds) are needed in which the viscous
resin-carbon
fiber layer is cured at a temperature of approx. 180 C. In the so-called RTM
(resin transfer
molding) process, carbon fiber textiles are added to the mold, the mold is
evacuated, and then the
resin is injected into the mold. After curing at approx. 180 C, the component
is removed from
the implement. Materials used for these molds are either C steels or an alloy
with a low
coefficient of expansion (iron with 36% nickel, Ni36) that typically has a
mean'thermal
expansion coefficient between 1.6 and 2.5 x 10-6 K-'.
The use of these RTM molds is associated with difficulties and significant
complexity because
after it is cured the component is difficult to release from the mold and in
addition the
component must undergo complex subsequent processing so that it can satisfy
its functional
demands.
The invention provides an alloy for these molds, with which alloy the
aforesaid difficulties
can be overcome or at least mitigated simply.
This is attained by using an iron-nickel-cobalt alloy in the CFC mold having
(in % by weight):
Ni 30 to 35%
Co 3 to 6%
Al 0.001 to 0.1%
Mn 0.005 to0.5%

CA 02637499 2011-09-01
29779-28
Si 0.005 to 0.5%
C Max. 0.1%
remainder Fe and constituents resulting from the production process,
the alloy having a mean thermal expansion coefficient of < 2.0 x 10-6/K in the
temperature range
from 20 to 200 C.
Depending on the application area, the Ni content can be adjusted ranging from
32 to 34.5%,
where needed even 32.5 to 33.5%.
One preferred alloy is distinguished by the following composition (in % by
weight):
Ni 32.5 to 34.5%
Co >3.0to5.5%
Al 0.001 to 0.5%
Mn 0,005 to 0.1 %
Si 0.005 to 0.1%
C 0.005 to 0.05%
remainder Fe and constituents resulting from the production process,
the alloy having a mean thermal expansion coefficient of < 1.5 x 10-6/K in the
temperature range
from 20 to 200 C.
The following elements with the given maximum contents can advantageously be
provided for
accompanying elements in the alloy to be used:
Cr maxØ1%
MO max. 0, 1%
Cu max. 0.1 %
Ti max. 0.1 %
Mg max. 0.005%
B max. 0.005%
2

CA 02637499 2011-09-01
29779-28
N max. 0.006%
0 max. 0.003%
S max. 0.005%
P max. 0.008%
Ca max. 0.005%
Zr max. 0.05%
Another alloy that can be used advantageously is distinguished by the
following chemical
composition (in % by weight):
Ni 32.5 to 33.5%
Co >3.5to<4.5%
Mo max. 0.05%
Cr max. 0.05%
C max. 0.009%
Mn max. 0.04%
Si max. 0.03%
S max. 0.003%
N max. 0.004%
Ti max. 0.01%
Cu max. 0.05%
P max. 0.005%
Al 0.001 to 0.05%
Mg max. 0.0008%
Ca max. 0.0003%
Zr max. 0.03%
0 max. 0.003%
remainder Fe and constituents resulting from the production process,
the alloy having a mean thermal expansion coefficient of < 1.3 x 10'6/K in the
temperature range
from 20 to 200 C.
The alloy may further contain 0.001 to 0.1 weight % Nb.
3

CA 02637499 2011-09-01
29779-28
Advantageously, the molds are made as milled parts from heat-formed (forged or
rolled) or cast
mass material and then annealed. The alloy can also be used in the form of
wire material, in
particular as an added welding substance when producing the mold. The alloy
can also be used
in the form of a large-format semi-finished product which is a sheet material,
strip material or
tube material.
One preferred application for the alloy is found in aircraft manufacture,
wherein it is possible to
use the alloy as a molded component, in particular for producing CFC fittings
using the RTM
technology. Other aircraft components that are also embodied using the light-
weight CFC
construction can also be produced with components made of the suggested alloy.
Compared to alloys based on Ni 36 that have been used in the past, components
can easily be
removed from molds of this alloy, because the thermal shrinkage of the mold is
lower after the
curing process. Given a suitable design for the mold, the component can be
removed such that it
can perform its function without subsequent processing.
The simpler removal of the component from the mold will also increase the
service life of the
mold, because no sharp-edged tools have to be used in order to release the
component from the
mold.
Table 1 provides examples of chemical compositions for inventive iron-nickel-
cobalt alloys (El,
E2, E3, E4, E5, E6) compared to other iron-nickel-cobalt alloys (TI, U1) that
were investigated.
4

CA 02637499 2008-07-17
Element (%) El E2 E3 E4 E5 E6
C 0.002 0.47 0.002 0.008 0.002 0.036
S 0.0023 0.0009 0.0006 0.0015 0.0004 0.0011
N 0.001 0.001 0.001 0.001
Cr 0.02 0.01 <0.01 <0.01 <0.01 0.01
Ni 34.20 34.25 32.75 32.80 32.80 32.55
Mn <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
Si 0.07 <0.01 <0.01 <0.01 <0.01 <0.01
Mo 0.01 0.02 0.01 0.01 0.05
Ti <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
Cu 0.01 <0.01 <0.01 <0.01 <0.01 <0.01
P 0.002 0.002 0.002 0.002 0.002 0.002
Al 0.004 0.007 0.001 0.005 0.005 0.014
Mg 0.0004 0.0003 0.0003 0.0003 0.0002 0.0003
Ca 0.0004 < 0.001 0.0006 0.0006 0.0007 < 0.001
Co 3.1 3.1 3.38 3.9 4.45 4.9
Fe Remainder Remainder Remainder Remainder Remainder Remainder
Element (%) Ti U1
C 0.004 0.002
S 0.0008 0.0025
N 0.001
Cr 0.01 0.02
Ni 35.50 34.20
Mn 0.03 < 0.01
Si 0.04 0.11
Mo 0.09
Ti < 0.01 < 0.01
Cu 0.05 0.01
P 0.002 0.003
Al 0.011 0.010
Mg 0.0006 0.0005
Ca 0.0002 0.0003
Co 1.44 2.3
Fe Remainder Remainder
Inventive alloys E 1 - E3 and E6 attain thermal expansion coefficients ranging
from 1.5 - < 2.0 x
10"6/K in the 20 - 200 C temperature range.

CA 02637499 2008-07-17
The inventive alloys E4 and E5 attain an even lower expansion coefficient of
about 1.3 x 10-6/K
in the 20 to 200 C temperature range so that with the alloys E4 and E5 a
combination of
increased strength with simultaneously lower thermal expansion is attained.
6