U.S. patent application number 12/224698 was filed with the patent office on 2009-04-30 for roll for metal processing, in particular a continuous casting roll, and method of producing such a roll.
Invention is credited to Gereon Fehlemann, Christian Geerkens, Albrecht Girgensohn, Erich Hovestadt, Michael Rzepczyk, Axel Weyer.
Application Number | 20090107648 12/224698 |
Document ID | / |
Family ID | 38016849 |
Filed Date | 2009-04-30 |
United States Patent
Application |
20090107648 |
Kind Code |
A1 |
Fehlemann; Gereon ; et
al. |
April 30, 2009 |
Roll for Metal Processing, in Particular a Continuous Casting Roll,
and Method of Producing Such a Roll
Abstract
The invention relates to a roll (1) for metal production and/or
metal processing, in particular a continuous casting roll, which
has a roll parent body (2) of metal and a coating (3) of
wear-resistant material applied to said roll parent body (2). In
order to make the roll, in particular the continuous casting roll,
especially wear-resistant, the invention provides for the coating
(3) to have electrolytically applied nickel, wherein the surface
(4) of the coating (3) forms the working surface of the roll (1).
Furthermore, the invention relates to a method of producing a roll
(1) for metal production and/or metal processing, in particular a
continuous casting roll.
Inventors: |
Fehlemann; Gereon;
(Dusseldorf, DE) ; Girgensohn; Albrecht;
(Dusseldorf, DE) ; Rzepczyk; Michael; (Dinslaken,
DE) ; Hovestadt; Erich; (Rhede, DE) ;
Geerkens; Christian; (Juchen, DE) ; Weyer; Axel;
(Wuppertal, DE) |
Correspondence
Address: |
FRIEDRICH KUEFFNER
317 MADISON AVENUE, SUITE 910
NEW YORK
NY
10017
US
|
Family ID: |
38016849 |
Appl. No.: |
12/224698 |
Filed: |
January 29, 2007 |
PCT Filed: |
January 29, 2007 |
PCT NO: |
PCT/EP2007/000740 |
371 Date: |
September 3, 2008 |
Current U.S.
Class: |
164/427 |
Current CPC
Class: |
F16C 13/00 20130101;
B22D 11/1287 20130101; F16C 2322/00 20130101; B21B 27/03
20130101 |
Class at
Publication: |
164/427 |
International
Class: |
B22D 11/06 20060101
B22D011/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2006 |
DE |
10 200600110384.5 |
Claims
1. A roll (1) for metal production and/or metal processing,
especially a continuous casting roll, which has a roll body (2)
made of metal and a coating (3) of wear-resistant material applied
on the roll body (2), where the coating (3) contains
electrodeposited nickel and where the surface (4) of the coating
(3) forms the working surface of the roll (1), wherein, besides
nickel, the coating (3) contains ceramic particles (5), which are
carbides of titanium (Ti), tantalum (Ta), tungsten (W), zirconium
(Zr), boron (B), chromium (Cr), and/or silicon (Si), or oxides of
aluminum (Al), chromium (Cr), silicon (Si), beryllium (Be), or
zirconium (Zr), where the amount of ceramic particles (5) in the
nickel or nickel alloy is 15-40 vol. %.
2. A roll in accordance with claim 1, wherein the amount of ceramic
particles (5) in the nickel or nickel alloy is 25-30 vol. %.
3. A roll in accordance with claim, wherein the thickness (D) of
the coating (3) is 0.01 mm to mm, and preferably 0.05 mm to 2
mm.
4. A roll in accordance with claim 1, wherein the coating (3)
consists of pure nickel.
5. A roll in accordance with claim 1, wherein, besides nickel, the
coating (3) contains one or more of the constituents cobalt (Co),
phosphorus (P), iron (Fe), zinc (Zn), copper (Cu), manganese (Mn),
and chromium (Cr).
6. A roll in accordance with claim 5, wherein the coating (3)
consists of a nickel-cobalt alloy in which ceramic particles (5) of
silicon carbide are incorporated.
7. A roll in accordance with claim 1, wherein the particle size (d)
of the ceramic particles (5) is 1-5 .mu.m.
8. A roll in accordance with claim 1, wherein the particle size (d)
of the ceramic particles (5) is 10 nm to 1,000 nm.
9. A roll in accordance with claim 1, wherein the hardness of the
surface (4) of the coating (3) is 300-500 HV1 and preferably
350-450 HV1.
Description
[0001] The invention concerns a roll for metal production and/or
metal processing, especially a continuous casting roll, which has a
roll body made of metal and a coating of wear-resistant material
applied on the roll body, where the coating contains
electrodeposited nickel and where the surface of the coating forms
the working surface of the roll.
[0002] The strand guide rolls have a great deal to do with the
satisfactory operation of a continuous casting plant as well as
with the quality of the cast product and the economy of the plant.
The function of the strand guide rolls is to support, guide, bend,
and convey the solidified strand after it has left the mold. In
this connection, the roll bodies and the bearings of the segmented
rolls are subject to high thermal, mechanical, and corrosive
chemical stresses.
[0003] The thermal stress arises from direct contact of the surface
of the roll body with the cast strand, which has a temperature of
800.degree. C. to 1,200.degree. C. The mechanical stress is the
result of ferrostatic forces, bending and straightening forces, and
drive forces that must be transferred from the roll to the strand.
In addition, the rolls are subject to wear due to friction with the
strand. Due to the large amounts of cooling water that are needed
and the high temperatures in combination with aggressive chemical
compounds, which are introduced, for example, by the use of casting
flux, it is also necessary to take into account the corrosion
characteristics and the corrosion protection of the materials and
parts used for the roll.
[0004] It is well known that the rolls of a continuous casting
plant can be produced from a heat-treatable steel as the base
material (e.g., 21 CrMoV 511 V, 16 CrMo 44, 24 CrMo 5, and S 355),
which is capable of absorbing the high mechanical stresses.
However, this steel is usually less well suited for permanently
withstanding the thermal and corrosive chemical stresses. To
realize adequate resistance to high temperatures and corrosive
chemical effects as well, it is known that buildup welding can be
used to cover the surface of the roll body with a soft martensitic
material. However, this technique is relatively cost-intensive.
[0005] A roll of this general type is known from EP 1 555 074 A1
and EP 1 468 761 A1. EP 1 582 279 A1 describes a similar solution.
WO 96/02340 describes a casting roll that is furnished with an
outer wear-resistant coating.
[0006] DE 40 27 225 C2 discloses a method for producing a
continuous casting roll that consists of a core of iron material
covered with a jacket of wear-resistant material. A layer of copper
or copper alloy is provided between the outer jacket and the core
of iron material. To optimize the thermal conductivity of the roll,
a nickel coating is electrodeposited on the layer of copper. This
intermediate nickel coating is then covered with a wear-resistant
cover layer of a nickel-chromium-boron alloy by buildup
welding.
[0007] U.S. Pat. No. 5,161,306 also proposes the application of a
wear-resistant layer on a roll body that is coated with
intermediate layers; in this case, the wear-resistant layer
consists of chromium oxides (Cr.sub.2O.sub.3).
[0008] US 2002/0056539 A1 also proposes the application of a
wear-resistant layer on a continuous casting roll; in this case,
the wear-resistant layer is based on nickel and contains carbon,
chromium, and molybdenum.
[0009] Other rolls with various wear-resistant coating materials
are disclosed by JP62-183950 A1, JP62-230462 A, JP63-086856 A,
JP60-030560 A, JP59-129754 A, and JP62-207549 A.
[0010] The objective of the invention is to remedy the
disadvantages described above and to create a roll, especially a
continuous casting roll, which has sufficient strength and at the
same time is capable of withstanding the thermal, abrasive
mechanical, and corrosive chemical stresses that arise during the
operation of the roll, with it being possible to operate the roll
for the longest time possible and with little or no geometric
change in the roll. At the same time, it must be possible to
produce the roll at low cost. A further objective of the invention
is to propose a corresponding method for producing a roll of this
description.
[0011] The solution to this problem by the invention is
characterized by the fact that, besides electrodeposited nickel as
the base material, the coating contains ceramic particles, which
are carbides of titanium (Ti), tantalum (Ta), tungsten (W),
zirconium (Zr), boron (B), chromium (Cr), and/or silicon (Si), or
oxides of aluminum (Al), chromium (Cr), silicon (Si), beryllium
(Be), or zirconium (Zr), where the amount of ceramic particles in
the nickel or nickel alloy is 15-40 vol. %, and preferably 25-30
vol. %.
[0012] The invention is thus novel in relation to previously known
solutions by virtue of the fact that the wear-resistant coating,
whose surface forms the working surface of the roll, is applied by
a galvanic, i.e., electrolytic, method.
[0013] The thickness of the coating applied by the galvanic or
electrolytic process is preferably 0.01 mm to 10 mm, and especially
0.05 mm to 2 mm.
[0014] In one embodiment of the invention, the coating consists of
pure nickel. However, it is preferred that the coating contain
other constituents besides nickel. Specifically, these other
constituents besides nickel can be, for example, one or more of the
constituents cobalt (Co), phosphorus (P), iron (Fe), zinc (Zn),
copper (Cu), manganese (Mn), and chromium (Cr).
[0015] In this connection, in a preferred embodiment, the coating
consists of a nickel-cobalt alloy in which ceramic particles of
silicon carbide are incorporated.
[0016] In accordance with a preferred embodiment, the particle size
of the ceramic particles is 1-5 .mu.m. In another embodiment, the
ceramic particles are much smaller, namely, 10 nm to 1,000 nm.
[0017] In accordance with an advantageous embodiment of the
invention, not the least of the advantages realized in this way is
that the hardness of the surface of the coating is 300-500 HV1
(Vickers hardness), and preferably 350-450 HV1.
[0018] A method for producing a roll for metal production and/or
metal processing, especially a continuous casting roll, involves
the following steps:
[0019] (a) production of a metal roll body;
[0020] (b) immersion of the roll body in an electrodeposition
bath;
[0021] (c) electrodeposition of a coating on at least part of the
surface of the roll body, where the coating consists at least
partly of nickel, and the surface of the coating forms the working
surface of the roll.
[0022] The proposal of the invention is thus no longer aimed at
providing the base material of the strand guide roll with a soft
martensitic surface layer that is welded on, as in the prior-art
methods, but rather at applying a coating of nickel or a nickel
alloy by electrodeposition.
[0023] In this connection, it is advantageous if a large number of
rolls can be simultaneously coated in electrodeposition baths, so
that the product costs per roll remain low. In addition, the
thickness of the applied coating can be easily defined and varied
by the residence time of the rolls in the electrodeposition
bath.
[0024] The electrodeposited coating is thin and effectively
protects the base material of the roll from corrosive attack. At
the same time, the coating is very hard and has good resistance to
high temperatures and good resistance to scaling. The wear
resistance of the continuous casting roll is reliably and
inexpensively improved in this way. The proposed rolls thus have a
longer service life, which results in a corresponding reduction of
costs for the operator of a continuous casting plant.
[0025] The drawings illustrate a specific embodiment of the
invention.
[0026] FIG. 1 shows a schematic side view of a continuous casting
roll.
[0027] FIG. 2 shows the detail Z from FIG. 1.
[0028] FIG. 3 is a schematic drawing of the setup of a galvanic or
electrolytic coating system with two continuous casting rolls to be
coated.
[0029] FIG. 1 shows a continuous casting roll 1, which consists of
a roll neck 9, which is of no further interest in the present
discussion, and of a roll body 2, which in the present embodiment
is cylindrical. The roll body 2 has a coating 3 of wear-resistant
material, the structure of which is illustrated in greater detail
in FIG. 2.
[0030] The coating 3 has a coating thickness D, which can be, for
example, 0.05 mm to 2.0 mm. The essential feature is that the
surface 4 of the coating 3 is the working surface of the roll 1. In
the case of a continuous casting roll, the working surface has
contact with the continuously cast strand, which is still hot, and
is thus subject to high thermal, mechanical, and corrosive chemical
stress.
[0031] The coating 3 consists of nickel or a nickel alloy, which is
applied to the roll body 2 galvanically (electrolytically) (in this
connection, see FIG. 3).
[0032] To increase especially the mechanical and thermal resistance
of the surface 4 of the roll 1, the surface is provided with a
considerable proportion of ceramic particles 5 with a mean particle
diameter d, which in one embodiment of the invention can vary
within the range of 1-5 .mu.m. However, an alternative embodiment
provides for the use of nanoparticles, i.e., the diameter d in this
case is within the range of 10 nm to 1,000 nm.
[0033] FIG. 3 illustrates the basic procedure for producing the
continuous casting roll 1. It shows a coating bath 6 that contains
a suitable plating solution for electrodeposition. The solution can
be an acid, e.g., sulfuric acid (H.sub.2SO.sub.4). An anode 7 is
submerged in the bath. It consists of an ingot of nickel and
constitutes the consumable electrode. In the example illustrated
here, two rolls 1 are also submerged in the coating bath. The roll
necks 9, which are not to be coated, are covered with covers (not
shown). The two rolls 1 constitute the cathode 8. The anode 7 and
cathode 8 are connected to a direct current source 10, which can be
regulated or automatically controlled by means that are already
well known in themselves.
[0034] When the current flows, a metallic precipitate that consists
of nickel is electrochemically deposited on the (uncovered) surface
of the rolls 1. The electric current removes metal ions from the
consumable electrode 7 and deposits them on the surface of the
rolls 1 by reduction. This causes the roll 1 to be coated uniformly
and on all sides with nickel. The longer the rolls 1 remain in the
bath 6, the thicker the coating 3 of nickel on the roll body 2
becomes.
[0035] The ceramic particles introduced in the coating make it
possible to optimize the mechanical/technological properties of the
nickel or nickel alloy coating for the each intended application.
In the present situation, it is desired that a continuous casting
roll be provided with a coating that is chemically resistant and
stable at high temperatures and has very low wear rates when
subjected to abrasive stress, but at the same time can be
economically processed during its manufacture. For example, nickel
compounds can be produced that have an average hardness of 350-450
HV1 at room temperature and can thus be worked with an acceptable
degree of effort and at the same time have low wear rates even at
higher temperatures.
[0036] Electrolytically produced metal alloy dispersions based on
nickel/cobalt, in which ceramic particles (preferably silicon
carbide) with a particle size of 1-5 .mu.m or ceramic nanoparticles
with a size of 10 to 1,000 nm are incorporated, are especially well
suited for the proposed application.
[0037] The nickel that is used is preferably high-purity nickel
that has been compressively prestressed.
[0038] Preferably, therefore, an electrolytic surface treatment of
the roll body is carried out, in which a high concentration of hard
solid particles is incorporated in a ductile nickel matrix. This
combination imparts very good wear resistance to the part to be
protected, for the cast strand then no longer runs directly on the
metal of the metal matrix but rather on the ceramic particles that
protrude from the base contour of the roll surface. This greatly
reduces the abrasion of the nickel and makes it possible to achieve
the goal of coating strand guide rolls for a long service life,
i.e., for at least 10 years of use.
[0039] In this regard, it is also conceivable that several coatings
can be electrodeposited on the roll body, and it is possible to
apply the same coating material each time or to use different
coating materials.
[0040] The continuous casting rolls can be used for all known
applications, i.e., especially in plants for the continuous casting
of carbon steel and stainless steel grades in ingots, round bars,
sections, slabs, and thin slabs. The roll diameter (final diameter
including the surface coating) of the strand guide roll is usually
in the range of 80-350 mm.
LIST OF REFERENCE SYMBOLS
[0041] 1 roll (continuous casting roll) [0042] 2 roll body [0043] 3
coating [0044] 4 surface of the coating [0045] 5 ceramic particle
[0046] 6 coating bath [0047] 7 anode (positive terminal) [0048] 8
cathode (negative terminal) [0049] 9 roll neck [0050] 10 direct
current source [0051] D thickness of the coating [0052] d particle
size of the ceramic particle
* * * * *