U.S. patent application number 09/916244 was filed with the patent office on 2001-11-29 for iron-nickel alloy having a low coefficient of expansion.
This patent application is currently assigned to IMPHY S.A.. Invention is credited to Baudry, Jacques, Faral, Michel, Tiers, Jean-Francois.
Application Number | 20010045246 09/916244 |
Document ID | / |
Family ID | 9469054 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010045246 |
Kind Code |
A1 |
Baudry, Jacques ; et
al. |
November 29, 2001 |
Iron-nickel alloy having a low coefficient of expansion
Abstract
Iron/nickel alloy having a low coefficient of expansion, the
chemical composition of which comprises iron, nickel, manganese,
silicon, calcium, magnesium, less than 0.005% of aluminum, less
than 0.001% of sulfur, less than 0.01% of oxygen, less than 0.005%
of nitrogen, and less than 0.003% of phosphorus, the chemical
composition furthermore satisfying the relationship:
S.ltoreq.0.02.times.Mn+0.8.times.Ca+0.6.times.Mg
Inventors: |
Baudry, Jacques; (Imphy,
FR) ; Faral, Michel; (Nevers, FR) ; Tiers,
Jean-Francois; (Sauvigny les Bois, FR) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
IMPHY S.A.
Immeudlb "La Pacific" 11/13 Cours Valmy-La Defense 7
Puteaux
FR
92800
|
Family ID: |
9469054 |
Appl. No.: |
09/916244 |
Filed: |
July 30, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09916244 |
Jul 30, 2001 |
|
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|
08562123 |
Nov 22, 1995 |
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Current U.S.
Class: |
148/336 ;
420/94 |
Current CPC
Class: |
C22C 38/08 20130101 |
Class at
Publication: |
148/336 ;
420/94 |
International
Class: |
C22C 038/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 23, 1994 |
FR |
94 14 011 |
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. An iron/nickel alloy having a coefficient of linear expansion
less than 0.9.times.10.sup.-6/K and having a chemical composition
which comprises iron and, by weight: 35.5%.ltoreq.Ni.ltoreq.37%
Mn.ltoreq.0.1% 0.03%.ltoreq.Si.ltoreq.0.15%
0.0001%.ltoreq.Ca.ltoreq.0.002% 0.0001%.ltoreq.Mg.ltoreq.0.002%
Al.ltoreq.0.005% S.ltoreq.0.001% O.ltoreq.0.01% N.ltoreq.0.005%
P.ltoreq.0.003% C.ltoreq.0.005% B.ltoreq.0.0004% H.ltoreq.0.001%
Cr.ltoreq.0.1% Cu.ltoreq.0.1% Mo.ltoreq.0.1% V.ltoreq.0.1%
Nb.ltoreq.0.1% Co.ltoreq.0.5%, wherein the chemical composition
satisfys the following relation:S.ltoreq.0.02.times.-
Mn+0.8.times.Ca+0.6.times.Mg.
2. The iron/nickel alloy as claimed in claim 1, wherein:
O.ltoreq.0.005% N.ltoreq.0.003% S.ltoreq.0.0005%.
3. The iron/nickel alloy as claimed in claim 1,
wherein:35.8%.ltoreq.Ni.lt- oreq.36.3%.
4. The iron/nickel alloy as claimed in claim 3,
wherein:35.9%.ltoreq.Ni.lt- oreq.36.2%.
5. The alloy as claimed in claim 1,
wherein:Cr+Cu+Mo+V+Nb+Si.ltoreq.0.15%.
6. The iron/nickel alloy as claimed in claim 2,
wherein:35.8%.ltoreq.Ni.lt- oreq.36.3%.
7. The alloy as claimed in claim 2,
wherein:Cr+Cu+Mo+V+Nb+Si.ltoreq.0.15%.
8. The alloy as claimed in claim 3,
wherein:Cr+Cu+Mo+V+Nb+Si.ltoreq.0.15%.
9. The alloy as claimed in claim 4,
wherein:Cr+Cu+Mo+V+Nb+Si.ltoreq.0.15%.
10. The iron/nickel alloy as claimed in claim 1, wherein said alloy
is in the form of a strip and is obtained by hot rolling and then
cold rolling the alloy, wherein a width of the strip is greater
than 400 mm and a coefficient of expansion of the strip between
20.degree. C. and 100.degree. C. is less than
0.9.times.10.sup.-6/K.
11. A shadow mask for a cathode ray tube comprising the alloy of
claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an iron/nickel alloy having
a low coefficient of linear expansion and to a product, preferably
a strip, comprising this alloy and obtained by hot rolling and
then, optionally, cold rolling.
[0003] 2. Discussion of the Background
[0004] Iron/nickel-containing alloys having a low coefficient of
expansion, containing between 35% and 40% by weight of nickel are
well known. However, in addition to nickel and iron, these alloys
always contain impurities such as sulfur, phosphorus, oxygen,
nitrogen and carbon, typically resulting from smelting. The alloys
may also contain elements such as cobalt, chromium, copper,
molybdenum, vanadium, niobium and silicon which are added to adjust
mechanical properties. Unfortunately, and because of the presence
of impurities, these alloys are difficult to hot-deform by rolling
or by forging. In order to improve the hot deformability, it is
known to add manganese in amounts greater than 0.2%. However such
addition has the drawback of appreciably increasing the coefficient
of expansion of the alloy.
[0005] In U.S. Pat. No. 2,050,387, a process has been proposed for
manufacturing an iron/nickel alloy having a low coefficient of
expansion and good hot forgeability, in which the alloy is smelted
by annealing high-purity raw materials under hydrogen above
1150.degree. C. for 20 h and then by casting and solidifying under
a hydrogen atmosphere. This process, however, has the drawback of
being complicated to implement and being very expensive.
OBJECTS OF THE INVENTION
[0006] One object of the present invention is to provide an
iron/nickel alloy with a low manganese content and a low
coefficient of linear expansion, which has good hot ductility and
which can be smelted using conventional processes.
[0007] Another object of the invention is to provide a product,
such as a strip, comprising the above-described iron/nickel alloy,
preferably by hot rolling and then, optionally, by cold rolling the
alloy.
DETAILED DESCRIPTION OF THE INVENTION
[0008] The above objects are provided by an iron/nickel alloy whose
chemical composition comprises, by weight:
[0009] 35.5%.ltoreq.Ni.ltoreq.37%
[0010] Mn.ltoreq.0.1%
[0011] 0.03%.ltoreq.Si.ltoreq.0.15%
[0012] 0.0001%.ltoreq.Ca.ltoreq.0.002%
[0013] 0.0001%.ltoreq.Mg.ltoreq.0.002%
[0014] Al.ltoreq.0.005%
[0015] S.ltoreq.0.001%
[0016] O.ltoreq.0.01%
[0017] N.ltoreq.0.005%
[0018] P.ltoreq.0.003%
[0019] In addition, the chemical composition satisfys the following
relationship:
S.ltoreq.0.02.times.Mn+0.8.times.Ca+0.6.times.Mg
[0020] and has, preferably, a balance of iron.
[0021] Preferably, the chemical composition is, in addition to the
above, such that:
[0022] O.ltoreq.0.005%
[0023] N.ltoreq.0.003%
[0024] S.ltoreq.0.0005%
[0025] In order to obtain good deep-drawability and a good surface
finish after heat treatment, it is preferable that the chemical
composition described initially or the preferable composition
immediately above further meet the following conditions:
[0026] C.ltoreq.0.005%
[0027] B.ltoreq.0.0004%
[0028] Preferably, the nickel content of the invention alloy is
between 35.8% and 36.3% and more preferably between 35.9% and
36.2%, and Cr.ltoreq.0.1%, Cu.ltoreq.0.1%, Mo.ltoreq.0.1%,
V.ltoreq.0.1%, and Nb.ltoreq.0.1%.
[0029] In order to obtain a very low coefficient of expansion, it
is preferable that the chemical composition of the invention alloy
meet the following condition: Cr+Cu+Mo+V+Nb+Si.ltoreq.0.15%.
[0030] The invention also relates to a product, preferably a strip,
made of the iron/nickel alloy according to the invention, obtained
by hot rolling and then, optionally, cold rolling. The strip
preferably has a width greater than 400 mm and a thickness as
desired, including 0.01-1 mm, the strip having a coefficient of
linear expansion between 20.degree. C. and 100.degree. C. which is
less than 0.9.times.10.sup.-6/K, preferably less than
0.82.times.10.sup.-6/K. The strip may be of any desired length.
[0031] The alloy according to the invention is an alloy based on
iron and nickel, containing iron and from 35.5% to 37% of nickel,
as well as, optionally, complementary alloy elements such as
cobalt, chromium, copper, molybdenum, vanadium or niobium in
amounts less than 3% by weight, these being intended to adjust the
mechanical properties depending on the intended uses.
[0032] The invention alloy contains less than 0.1% by weight and
preferably less than 0.05% by weight of manganese, since this
element increases the coefficient of thermal expansion of the
alloy.
[0033] The low manganese content of the invention alloy has the
drawback of adversely affecting the hot deformability (hot
ductility) of the alloy, and in order to obtain good hot ductility
it is necessary for the alloy to contain in combination:
[0034] less than 0.001%; and preferably less than 0.0005% of sulfur
where "%" here and everywhere herein means % by weight,
[0035] less than 0.003% of phosphorus,
[0036] between 0.0001% and 0.002% of calcium,
[0037] between 0.0001% and 0.002% of magnesium,
[0038] between 0.03% and 0.015% of silicon.
[0039] The manganese, calcium, magnesium and sulfur contents also
satisfy the relation:
S.ltoreq.0.02.times.Mn+0.8.times.Ca+0.6.times.Mg
[0040] The calcium and magnesium contents are limited herein to
0.002% in order to prevent the formation of large inclusions liable
to cause pitting during chemical cutting, as is particularly the
case when the invention alloy is used in the form of thin steets
for the manufacture of shadow masks for cathode ray tubes.
[0041] It is also necessary, in order to obtain good hot ductility,
for the invention alloy to contain less than 0.005% of aluminum and
less than 0.005% and preferably less than 0.003% of nitrogen. It
also contains less than 0.01% and preferably less than 0.005% of
oxygen.
[0042] In order to obtain the lowest coefficient of expansion
possible, the nickel content herein is preferably between 35.8% and
36.3% and, even better, between 35.9% and 36.2%, the optimum
content being 36.05%.
[0043] The alloy elements chromium, copper, molybdenum, vanadium,
niobium and silicon have an unfavorable effect on the coefficient
of expansion. In addition, when searching for the lowest possible
coefficient of expansion, the contents of each of these elements
must remain less than 0.1% and preferably less than 0.05%. Even
better, it is desirable that:
Cr+Cu+Mo+V+Nb+Si.ltoreq.0.15%
[0044] Cobalt is an element which may be partially substituted for
nickel up to a level of 10%, but this element has drawbacks when
the alloy has to undergo chemical attack, for example in order to
perform chemical etching; in addition, its content is preferably
limited to 0.5%, especially when the alloy is intended for
manufacturing shadow masks for cathode ray tubes.
[0045] When the invention alloy is used to manufacture thin sheets
intended to be creep drawn, it preferably contains less than 0.02%
and more preferably less than 0.010%, and even better less than
0.005%, of carbon so as to have the lowest possible yield stress,
which is favorable to good deep-drawability.
[0046] The hydrogen content of the invention alloy is preferably
less than 0.001% and preferably less than 0.0005% in order to
prevent the formation of blisters. The boron content is preferably
less than 0.01% and more preferably less than 0.005%, and even
better less than 0.0004%, so as to prevent the formation of boron
nitrides at the surface of the products during heat treatments.
These nitrides form a pulverulent layer which leads to poor
adhesion of the blacking layer produced on shadow masks.
[0047] The invention alloy makes it possible to manufacture
products such as ingots or slabs by hot rolling and to then
produce, e.g., thin strips with thicknesses less than 0.3 mm and
width greater than 400 mm, by cold rolling, these strips being used
especially for the manufacture of shadow masks for cathode ray
tubes.
[0048] The invention will now be further described by way of an
example. This example is nonlimiting, however.
EXAMPLE
[0049] A 600 mm wide and 0.15 mm thick strip was manufactured by
hot-rolling and then cold-rolling an ingot of iron/nickel alloy
whose chemical composition was, by weight,:
[0050] Ni: 35.97%
[0051] Co: 0.019%
[0052] Cr: 0.025%
[0053] Cu: <0.01%
[0054] Mo: 0.0058%
[0055] V: <0.005%
[0056] Nb: <0.005%
[0057] Mn: 0.041%
[0058] Si: 0.048%
[0059] S: <0.0005%
[0060] Ca: 0.0002%
[0061] Mg: 0.0003%
[0062] Al: <0.005%
[0063] O: 0.0045%
[0064] C: 0.0033%
[0065] N: 0.0032%
[0066] P: <0.003%
[0067] H: <0.001%
[0068] B: <0.0004%
[0069] When the contents of elements above are indicated as being
"less than" a certain value, this means that they are contained in
amounts less than the limit of sensitivity of the analytical
methods used.
[0070] Hot rolling was carried out without forming crazes. The
coefficient of expansion was 0.81.times.10.sup.-6/K. After heat
treatment for 30 minutes at 800.degree. C., the yield stress
E.sub.0.2 was 270 MPa and the coercive field was 0.45 Oe. The strip
exhibited very good chemical etching behavior. All these properties
make it particularly suitable for the manufacture of shadow masks
for cathode ray tubes. The alloy according to the invention may
also be used, for example, in metrology or for the manufacture of
bimetallic strips.
[0071] This application is based on French patent application 94 14
011 filed Nov. 23, 1994, incorporated herein by reference.
Obviously, numerous modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
* * * * *