U.S. patent application number 10/552310 was filed with the patent office on 2007-05-17 for iron-chromium-aluminum alloy.
Invention is credited to Heike Hattendorf, Ralf Hojda, Angelika Kolb-Telieps.
Application Number | 20070110609 10/552310 |
Document ID | / |
Family ID | 32185994 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070110609 |
Kind Code |
A1 |
Hattendorf; Heike ; et
al. |
May 17, 2007 |
Iron-chromium-aluminum alloy
Abstract
The invention relates to an iron-chromium-aluminum alloy having
a good oxidation resistance, comprising (in % by mass) 2.5 to 5.0%
Al, 10 to 25% Cr, 0.05 0.8% Si, and additions of >0.01 to 0.1% Y
and/or >0.01 to 0.1% Hf and/or >0.01 to 0.2% Zr and/or
>0.01 to 0.2% Cerium mischmetal (Ce, La, Nd) as well as
production-associated impurities.
Inventors: |
Hattendorf; Heike; (Werdohl,
DE) ; Kolb-Telieps; Angelika; (Ludenscheid, DE)
; Hojda; Ralf; (Altena, DE) |
Correspondence
Address: |
JORDAN AND HAMBURG LLP
122 EAST 42ND STREET
SUITE 4000
NEW YORK
NY
10168
US
|
Family ID: |
32185994 |
Appl. No.: |
10/552310 |
Filed: |
March 8, 2004 |
PCT Filed: |
March 8, 2004 |
PCT NO: |
PCT/DE04/00454 |
371 Date: |
December 5, 2006 |
Current U.S.
Class: |
420/40 |
Current CPC
Class: |
Y02A 50/20 20180101;
C22C 38/18 20130101; Y02T 10/12 20130101; B01D 53/945 20130101;
C22C 38/005 20130101; C22C 38/42 20130101; B01D 2258/012 20130101;
C22C 38/004 20130101; C22C 38/06 20130101 |
Class at
Publication: |
420/040 |
International
Class: |
C22C 38/18 20060101
C22C038/18 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2003 |
DE |
103 10 865.3 |
Claims
1.-19. (canceled)
20. Iron-chromium-aluminium alloy having good oxidation resistance,
comprising, in % by weight, as follows: 2.5 to 5.0% Al; 10 to 25%
Cr; 0.05-0.8% Si; and >0.01 to 0.1% of a total weight of Y, Sc,
Ti, Nd, Ta, V, and/or one or more rare earth metal elements; and/or
>0.01 to 0.1% of a total weight of Hf, Sc, Ti, Nd, Ta, V, and/or
one or more rare earth metal elements; and/or >0.01 to 0.2% of a
total weight of Zr, Sc, Ti, Nd, Ta, V, and/or one or more rare
earth metal elements; and/or >0.01 to 0.2% of a total weight of
Cerium mischmetal (Ce, La, Nd), Sc, Ti, Nd, Ta, V, and/or one or
more rare earth metal elements, said Cerium mischmetal (Ce, La, Nd)
comprising at least two of Ce, La, or Nd.
21. The alloy in accordance with claim 20, comprising: >0.01 to
0.1% Y and/or >0.01 to 0.1% Hf and/or >0.01 to 0.2% Zr and/or
>0.01 to 0.2% Cerium mischmetal (Ce, La, Nd).
22. The alloy in accordance with claim 20, comprising, in % by
weight, 2.5 to <5% Al; 13 to 21% Cr; >0.01 to 0.1% Y; and
>0.01 to 0.1% Hf.
23. The alloy in accordance with claim 20, comprising, in % by
weight, 2.5 to <5% Al; 13 to 21% Cr; >0.01 to 0.1% Y;
>0.01 to 0.1% Hf; and >0.01 to 0.2% Zr.
24. The alloy in accordance with claim 20, comprising, in % by
weight, 2.5 to 5% Al; 13 to 21% Cr; and >0.01 to 0.2% Cerium
mischmetal (Ce, La, Nd).
25. The alloy in accordance with claim 20, comprising, in % by
weight, 2.5 to 5% Al; 13 to 21% Cr; >0.01 to 0.2% Zr; and
>0.01 to 0.2% Cerium mischmetal (Ce, La, Nd).
26. The alloy in accordance with claim 20, comprising, in % by
weight, max. 0.06% C; max. 0.6% Si; max. 0.6% Mn; max. 0.04% P;
max. 0.01% S; max. 0.02% N; max. 0.1% Ti; and in total max. 0.5%
Nb, Mo, Cu and/or W.
27. The alloy in accordance with claim 20, comprising Sc, Ti, Nd,
Ta, V and/or one or more rare earth metal elements.
28. The alloy in accordance with claim 20, comprising, in % by
weight, Cr between 14 and 19%; and Al between 2.5 and 4.5%, wherein
the total content, in % by weight, of Y, Hf, Zr, Cerium mischmetal
(Ce, La, Nd), Sc, Ti, Nb, Ta, V and/or one or more rare earth
metals does not exceed 0.6%.
29. The alloy in accordance with claim 28, wherein, in % by weight,
the Cr content is >17.5% and <19% and the Al content is
>3% and <4%.
30. The alloy in accordance with claim 20, wherein, in % by weight,
the Y content is >0.02% and <0.08% and the Hf content is
>0.02% and <0.06%.
31. The alloy in accordance with claim 20, wherein said Cerium
mischmetal (Ce, La, Nd) comprises Ce, La, and Nd.
32. The alloy in accordance with claim 21, wherein said Cerium
mischmetal (Ce, La, Nd) comprises Ce, La, and Nd.
33. Components comprising the alloy in accordance with claim 20,
wherein said components, after being annealed at 1100.degree. C.
for 400 h at a thickness of 50 .mu.m, show a linear deformation of
<4%.
34. A method for the fabrication of semi-finished articles
comprising the alloy in accordance with claim 20, comprising
melting the alloy; and performing ingot casting, continuous casting
or strip casting; and/or hot and/or cold deformation; and/or
performing one or more intermediate annealing processes.
35. A component in Diesel vehicles and two-stroke devices, said
component comprising the alloy in accordance with claim 20.
36. The component in accordance with claim 35, wherein said Diesel
vehicles and two-stroke devices comprise Diesel and two-stroke
engines.
37. The component in accordance with claim 36, wherein said
component is a substrate foil in metallic catalytic exhaust
converters.
38. Exhaust cleaning systems, comprising the component in
accordance with claim 36, wherein said component is formed in a
shape of a wire.
39. Diesel engine glow cells comprising the component in accordance
with claim 36.
40. Components employed in exhaust systems of Diesel or two-stroke
engines comprising a surface coating, said surface coating formed
by applying said surface coating from a spraying wire comprising
the alloy in accordance with claim 20.
41. The component in accordance with claim 36, wherein said
component is a heating conductor or resistance material for
electrical preheating of exhaust cleaning systems of Diesel or
two-stroke engines.
42. Exhaust cleaning systems of fuel cells comprising a component
comprising the alloy in accordance with claim 20.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The invention relates to an iron-chromium-aluminium alloy
having good oxidation resistance.
[0003] 2. Description of Related Art
[0004] Although the catalytic converter is the rule in
four-stroke-engines today, the development of catalytic converters
for Diesel and two-stroke engines is still in its beginnings. In
four-stroke-engines, alloys are used which are similar to those
described in EP-A 0387 670: with (in % by weight) 20-25% Cr, 5-8%
Al, max. 0.01% P, max. 0.01% Mg, max. 0.5% Mn, max. 0.005% S,
residual iron and unavoidable impurities and, if required, alloying
elements, such as 0.03-0 08% Y, 0.004-0.008% N, 0.02-0.04% C,
0.035-0.07% Ti, 0.035-0.07% Zr. Since production by traditional
methods, namely conventional pouring of the alloy and subsequent
hot and cold deformation, is very difficult where aluminium
contents of below 6% by weight are concerned and in cases of higher
aluminium contents is no longer workable in large-scale
productions, alternative production methods have been
developed.
[0005] U.S. Pat. No. 5,366,139, for instance, discloses a method
whereby foils of iron-chromium-aluminium alloys are produced by way
of suitable iron-chromium steel being coated on both sides with
aluminium or aluminium alloys by way of roll cladding. This
composite metal is processed exclusively by cold deformation and is
subjected to diffusion annealing to produce a homogeneous
structure.
[0006] A further method whereby the coating is achieved by way of
hot dip aluminizing is disclosed in DE-A 198 34 552. The latter
foil has the following chemical composition (all details in % by
weight): 18-25% Cr, 4-10% Al, 0.03-0.08% Y, max. 0.01% Ti,
0.01-0.05% Zr, 0.01-0.05% Hf, 0.5-1.5% Si, residual iron and
method-associated impurities. Foils fabricated with this alloy were
to date used in four-stroke-combustion engines.
BRIEF SUMMARY OF THE INVENTION
[0007] It is the object of the present invention to produce an
alloy for applications in the temperature range of 250.degree. C.
to 1000.degree. C. having an adequate oxidation resistance which is
also achievable in large scale productions.
[0008] The solution to the task set is provided by an
iron-chromium-aluminium alloy having good oxidation resistance,
with (in % by weight) 2.5 to 5.0% Al and 10 to 25% Cr and 0.05-0.8%
Si as well as additions of >0.01 to 0.1% Y and/or >0.01 to
0.1% Hf and/or >0.01 to 0.2% Zr and/or >0.01 to 0.2% Cerium
mischmetal (Ce, La, Nd) (i.e., at least two of Ce, La, or Nd) as
well as production-associated impurities.
[0009] A preferred iron-chromium-aluminium alloy having good
oxidation resistance has the following composition (in % by
weight): 2.5-5% Al and 13 to 21% Cr as well as alternative
additions of: [0010] >0.01 to 0.1% Y and >0.01 to 0.1% Hf;
[0011] >0.01% to 0.1% Y and >0.01 to 0.1% Hf and >0.01% to
0.2% Zr; [0012] >0.01 to 0.2% Cerium mischmetal (Ce, La, Nd);
[0013] >0.01 to 0.2% Zr and >0.01 to 0.2% Cerium mischmetal
(Ce, La, Nd) as well as production-associated impurities.
[0014] Surprisingly, it has been found that, in Diesel engines and
two-stroke engines, aluminium contents above 5% are not required.
2.5 to 5.0% by weight are quite sufficient to guarantee an adequate
oxidation resistance in the temperature range of 250.degree. C. to
1000.degree. C. which is of interest in this regard, as the
examples presented below will show. Indispensable in this situation
are the additions of reactive elements to guarantee the oxidation
resistance. Particularly proven are 0.01-0.1% Y and/or 0.01-0.1%
Hf, where, in the presence of both elements, the sum of both these
elements must not exceed 0.15% by weight, because at this level the
positive effect of the oxidation resistance will be reversed to a
negative. However, also by adding other oxygen-affine reactive
elements, such as for instance Zr, Cerium mischmetal and La,
positive effects can be achieved in relation to the oxidation
resistance of the alloy.
[0015] One method for the fabrication of semi-finished articles
from this alloy is characterised in that the semi-finished article
following melting of the alloy by way of ingot casting or
continuous casting as well as hot and cold deformation may be
required to undergo one (or more) intermediate annealing
processes.
[0016] Advantageous embodiments of the method are described in the
disclosure.
[0017] The production of a foil of 50 .mu.m or even 20 .mu.m
thickness is possible in the conventional manner in such
compositions. The slabs can even be produced by way of the
particularly inexpensive continuous casting process which in the
presence of higher aluminium contents is, as a rule, connected with
high losses.
[0018] Preferred applications for this alloy are: [0019] components
in exhaust systems of Diesel engines in vessels, Diesel engines and
two-stroke engines of motor vehicles (cars, trucks) or motorbikes;
[0020] substrate foils in metallic catalytic converters of Diesel
engines and two-stroke engines; [0021] components in Diesel engine
glow plugs; [0022] knitted metal fabrics and mats for exhaust
cleaning systems used in for instance motorcycles, brush cutters,
lawn mowers and power saws; [0023] components for exhaust cleaning
systems for fuel cells; [0024] spraying wires for surface coatings
of components employed in exhaust systems of diesel and two-stroke
systems; [0025] heating conductors or resistance materials for
electrical preheating of exhaust cleaning systems in Diesel and
two-stroke systems.
[0026] The subject of the invention is described in greater detail
in the following examples.
DETAILED DESCRIPTION
[0027] (Aluchrom ISE, Hf3 and Hf4 represent comparative alloys and
Aluchrom Hf1 and Hf2 are the subject of the present invention).
[0028] Chemical Compositions TABLE-US-00001 Chemische
Zusammensetzungen Element/ Aluchrom Aluchrom Aluchrom Aluchrom
Aluchrom Masse % ISE Hf 1 Hf 2 Hf 3 Hf4 Cr 20.45 17.25 18.20 21.05
20.15 Ni 0.19 0.14 0.16 0.17 0.16 Mn 0.25 0.28 0.15 0.11 0.21 Si
0.43 0.54 0.29 0.30 0.22 Tl 0.01 <0.01 <0.01 <0.01 0.01 Cu
0.03 0.05 0.02 0.03 0.07 S 0.002 0.002 0.002 0.002 0.002 P 0.011
0.009 0.013 0.009 0.012 Al 5.27 2.78 3.30 5.36 5.70 Mg 0.008 0.004
0.009 0.009 0.009 Zr 0.003 0.05 0.01 0.02 0.05 V 0.04 0.05 0.03
0.04 0.03 C 0.006 0.032 0.023 0.051 0.023 N 0.004 0.005 0.004 0.002
0.005 Hf -- 0.04 0.05 0.03 0.05 Y -- 0.03 0.05 <0.01 0.06 Cer MM
0.015 -- -- -- (Ce, La, Nd)
[0029] The examples in accordance with the invention were produced
by melting in the electric arc furnace, continuous casting or ingot
casting, hot rolling to a thickness of about 3 mm, with
intermediate annealing at end thicknesses of 0.02 to 0.05 and cold
rolling on a 20 roller scaffold.
Oxidation Test
[0030] As the examples show, besides the Al content, the exact
tuning of the oxygen affine reactive elements is of predominant
importance. For instance, the alloys according to the present
invention, Aluchrom Hf1 and Aluclirom Hf2, in spite of their
comparatively low Al-content of around 3%, show an extremely good
oxidation resistance, which is similar to the comparative alloys
Aluclirom ISE and Aluchrom Hf4. By comparison, Aluchrom Hf3, in
spite of its high Al-- content of 5.36%, has lower values which can
be attributed to the Y content being too low. In this instance
therefore additions of Y or Cerium mischmetal result in a markedly
improved oxidation resistance. (compare Aluchrom ISE and Aluchrom
Rf4).
[0031] A further important aspect for the construction of metallic
catalytic converter substrates for Diesel engines and two-stroke
engines is the dimensional stability of the foil during the useful
life of the foil. A respective characteristic feature in this
regard is the linear deformation which should, if possible, not
exceed 4%.
Dimensional Stability
[0032] This also shows that the alloys in accordance with the
present invention, Aluchrom Hf1 and Aluchrom Hf2, having an al
content of around 3%, achieve a dimensional stability of <4% as
do the comparative alloys Aluchrom ISE and Aluchrom Hf4 having an
al content of >5%. Also in this case, in spite of their
comparatively high Al content of 5.36% but too low a Y content, the
comparative alloy Aluchrom Hf3 does not meet the requirements,
since the linear deformation after 400 h, being about 5%, is
clearly too great.
[0033] Thus it is surprisingly found that with a suitable tuning of
the oxygen-affine reactive elements, even where Al contents clearly
below 5% are present, a dimensional stability necessary for the
production of metallic catalytic converters can be achieved.
[0034] A cost-effective production, based on the comparatively low
Al contents, by way of ingot casting, continuous casting or even
strip casting whilst observing the application-specific parameters
is thus achieved.
* * * * *