Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
Title of Invention: A METHOD FOR DIFFUSING AND PERMEATING
CREEP REINFORCEMENT MATERIAL INTO HEAT-RESISTANT METAL
MEMBER, AND HEAT-RESISTANT METAL MEMBER WITH ENHANCED CREEP
STRENGTH
Technical Field
[0001]
The present invention relates to a method for diffusing
and permeating a creep reinforcement material into a
heat-resistant metal member, and to a heat-resistant metal
member with creep strength enhanced by such a method.
Background Art
[0002]
Hitherto, as a method for enhancing creep properties of
a heat-resistant metal material, a method has been developed
in which, for example, a grain boundary strengthening element
that affects creep strength and/or fatigue strength is coated
or thermally sprayed to forma film, and heated for a specific
duration at a specific temperature (see Japanese Patent No.
3793966).
Summary of Invention
[0003]
An object of the present invention is to provide a method
capable of efficiently diffusing and permeating a material
that enhances creep strength (hereinafter referred to as a
"creep reinforcement material") into a member manufactured
using a heat-resistant metal material (hereinafter referred
to as a "heat-resistant metal member"), and to provide a
heat-resistant metal member with creep strength enhanced by
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such a method.
[0004]
In view of the above problem, according to the present
invention, a method for diffusing and permeating a creep
reinforcement material into a heat-resistant metal member, and
a heat-resistant metal member with creep strength enhanced by
such a method, include the following configuration. More
specifically, the present invention includes:
(1) a method for diffusing and permeating a creep reinforcement
material into a heat-resistant metal member, the method
comprising: coating or thermally spraying a creep reinforcement
material onto a surface of a heat-resistant metal member;
covering, by a heat-resistant covering member, a section coated
or thermally sprayed with the creep reinforcement material, and
securing the heat-resistant covering member so as to contact
the section; and heating the heat-resistant metal member covered
by the heat-resistant covering member to a temperature of 1000 C
or greater, wherein the creep reinforcement material contains
B, W, Cr, Mo, Nb V, Hf, Zr, Ti, Cu, or Co, or any combination
thereof, wherein the heat-resistant covering member is a member
made from a material that is able to maintain a profile of the
heat-resistant metal member at a heating temperature of the
heat-resistant metal member and is different from the creep
reinforcement material, wherein the heat-resistant metal member
is made of 0.3Mo steel, 0.5Mo steel, 0.5Cr-0.5Mo steel, 1Cr-
0.2Mo steel, 1Cr-0.5Mo steel, 1.25Cr-0.5Mo steel, 2.25Cr-lMo
steel, 5Cr-0.5Mo steel, 7Cr-0.5Mo steel, 90r-lMo steel, 0.3Cr-
Mo-V steel, 0.5Cr-Mo-V steel, 9Cr-Mo-V steel, 12Cr-Mo-V steel,
1Cr-1.25Mo-0.25V steel, 9Cr-lMo-W steel, SUS304, SUS304L,
SUS316, SUS316L, SUS316TI, SUS317, SUS321, SUS347H, SUS310S,
Super304, SUS904L, NCF600, NCF601, NCF800, or NCF800H, and
wherein the heat-resistant covering member is a ceramic or an
alloy;
(2) the method described in (1), wherein the heat-resistant
covering member is a ceramic comprising alumina, zirconia,
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aluminum nitride, silicon carbide, silicon nitride, cordierite,
sialon, zircon or mullite:
(3) the method described in (1), wherein the heat-resistant
covering member is an alloy comprising Alloy 903, Alloy 909 or
HRA 929;
(4) the method described in (1) to (3) wherein, the heat-
resistant metal member is made of metal containing steel as a
main component, and after heating the heat-resistant metal
member covered by the heat-resistant covering member to a
temperature of 1000 C or greater, the heat-resistant metal
member covered by the heat-resistant covering member is cooled
and re-heated to a temperature of an Al transformation point or
greater;
(5) a heat-resistant metal member with enhanced creep strength,
the heat-resistant metal member being obtained by coating or
thermally spraying a creep reinforcement material onto a surface
of a heat-resistant metal member, covering, by a heat-resistant
covering member, a section coated or thermally sprayed with the
creep reinforcement material, and securing the heat-resistant
covering member so as to contact the section, and heating the
heat-resistant metal member covered by the heat-resistant
covering member to a temperature of 1000 C or greater; and the
creep reinforcement material containing B, W, Cr, Mo, Nb, V,
Hf, Zr, Ti, Cu, or Co, or any combination thereof wherein the
heat-resistant covering member is a member made from a material
that is able to maintain a profile of the heat-resistant metal
member at a heating temperature of the heat-resistant metal
member and is different from the creep reinforcement material,
wherein the heat-resistant metal member is made of 0.3Mo steel,
0.5Mo steel, 0.5Cr-0.5Mo steel, 1Cr-0.2Mo steel, 1Cr-0.5Mo
steel, 1.25Cr-0.5Mo steel, 2.25Cr-lMo steel, 5Cr-0.5Mo steel,
7Cr-0.5Mosteel, 9Cr-lMo steel, 0.3Cr-Mo-V steel, 0.5Cr-Mo-V
steel, 9Cr-Mo-V steel, 12Cr-Mo-V steel, 1Cr-1.25Mo-0.25V steel,
9Cr-lMo-W steel, SUS304, SUS304L, SUS316, SUS3161,, SUS316TI,
SUS317, SUS321, SUS347H, SUS310S, Super304, SUS904L, NCF600,
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NCF601, NCF800, or NCF800H, and wherein the heat-resistant
covering member is a ceramic or an alloy;
(6) the heat-resistant metal member described in (5), wherein
the heat-resistant covering member is a ceramic comprising
alumina, zirconia, aluminum nitride, silicon carbide, silicon
nitride, cordierite, sialon, zircon or mullite;
(7) the heat-resistant metal member described in (5), wherein
the heat-resistant covering member is an alloy comprising Alloy
903, Alloy 909 or HRA 929; and
(8) the heat-resistant metal member described in (5) to (7)
wherein the heat-resistant metal member is made of metal
containing steel as a main component, and the heat-resistant
metal member is obtained by, after heating the heat-resistant
metal member covered by the heat-resistant covering member to
a temperature of 1000 C or greater, cooling and re-heating to
a temperature of an AI transformation point or greater.
[0005]
The present invention is directed to a method capable of
efficiently diffusing and permeating a creep reinforcement
material into a heat-resistant metal member, and provision of
a heat-resistant metal member with creep strength enhanced by
such a method.
Brief Description of Drawings
[0006]
Fig. 1 is a schematic diagram illustrating a method to
diffuse and permeate a creep reinforcement material into a heat-
resistant metal member, to explain an embodiment of the present
invention.
Fig. 2 is a schematic cross-section illustrating a cross-
section of Fig. 1, to explain an embodiment of the present
invention.
Description of Embodiments
[0007]
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Detailed explanation follows regarding preferable
embodiments of the present invention, with reference to the
appended drawings. Note that the objects, features,
advantages, and ideas of the present invention will be clear
to a person of ordinary skill in the art from the content of
the present specification, and a person of ordinary skill in
the art would easily be able to reproduce the present invention
from the present specification. The following embodiments,
drawings, and the like of the present invention illustrate
preferable embodiments of the present invention, and are
there to give examples and for the purpose of explanation;
however, the present invention is not limited thereto. It
will be obvious to a person of ordinary skill in the art that
various modifications may be implemented based on the content
of the present specification within the intention and scope
of the present invention disclosed in the present
specification.
[0008]
Fig. 1 is a schematic diagram illustrating a method for
diffusing and permeating a creep reinforcement material into
a heat-resistant metal member, to explain an embodiment of
the present invention. Fig. 2 is a schematic cross-section
illustrating a cross-section of Fig. 1, to explain an
embodiment of the present invention. In the present
embodiment, explanation is of an example of a case in which
an already installed (including repaired cases thereof) or
unused, or a degraded, high temperature pipe manufactured
using a heat-resistant metal material, is employed as a
heat-resistant metal member 10, however, there is no
limitation thereto. The heat-resistant metal member 10 may
be another high temperature member manufactured using a
heat-resistant metal material, such as an already installed
(including repaired cases thereof) or unused, or a degraded,
turbine.
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[0009]
As illustrated in Fig. 1 and Fig. 2, in the method according
to the present invention for diffusing and permeating a creep
reinforcement material into a heat-resistant metal member 10,
5 first the creep reinforcement material is coated or thermally
sprayed onto a surface of the heat-resistant metal member 10.
Then a section 25 onto which the creep reinforcement material
has been coated or thermally sprayed is covered by a
heat-resistant covering member 30, and the heat-resistant
covering member 30 is secured so as to make contact with the
section 25. Next, the heat-resistant metal member 10 covered
by the heat-resistant covering member 30 is heated for a
specific duration at a temperature of 1000 C or greater using
a heater 40.
[0010]
As mentioned above, the heat-resistant metal member 10
coated or thermally sprayed with the creep reinforcement
material is covered by the heat-resistant covering member 30
and is heated to a temperature of 1000 C or greater, and thus
compressive force acts on the heat-resistant metal member as
it thermally expands in a direction toward an outer periphery,
restraining thermal expansion of the heat-resistant metal
member in the direction toward the outer periphery, and
enabling the creep reinforcement material on the surface of
the heat-resistant metal member 10 to be efficiently diffused
and permeated into the heat-resistant metal member 10. Thus,
in cases in which the heat-resistant metal member 10 is a
degraded member or an already installed member, by utilizing
the force from thermal expansion in the direction toward the
outer periphery of the heat-resistant metal member 10, creep
voids and cracks in the heat-resistant metal member 10 and
a weld 20 thereof are efficiently repaired, enabling
regeneration of the heat-resistant metal member 10 and the
weld 20 thereof to be achieved. Moreover, structural
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strengthening of the heat-resistant metal member 10 and the
weld 20 thereof can be achieved accompanying restoration of
the structure of the heat-resistant metal member 10 and the
weld 20 thereof. The creep strength is accordingly enhanced,
enabling the lifespan to be extended to that of a new member
or greater. On the other hand, in cases in which the
heat-resistant metal member 10 is an unused member,
structural strengthening of the heat-resistant metal member
and the weld 20 thereof can be achieved, thereby enhancing
10 the creep strength and enabling the lifespan to be extended
to that of a new member or greater.
[0011]
In the method for diffusing and permeating a creep
reinforcement material into the heat-resistant metal member
10 according to the present invention, etching treatment, or
shot peening and etching treatment, may be performed on the
section 25 to be coated or thermally sprayed with the creep
reinforcement material prior to coating or thermally spraying
the creep reinforcement material on the surface of the
heat-resistant metal member 10. Such proces sing enables work
hardening of the surface layer of the heat-resistant metal
member 10 to be performed by plastic deformation, enables
residual compressive stress to be imparted to the surface of
the heat-resistant metal member 10, and enables any oxidized
film on the surface of the heat-resistant metal member 10 to
be removed.
[0012]
In the method for diffusing and permeating a creep
reinforcement material into the heat-resistant metal member
10 according to the present invention, processing to remove
(reduce) residual stress, such as stress relief or tension
annealing processing, may be performed after the
heat-resistant metal member 10 covered by the heat-resistant
covering member 30 has been heated to a temperature of 1000 C
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or greater using the heater 40. More specifically, after the
heat-resistant metal member 10 covered by the heat-resistant
covering member 30 has been heated to a temperature of 1000 C
or greater using the heater 40, the heat-resistant metal
member 10 may be first cooled to room temperature, then
reheated to a temperature of an Ai transformation point or
greater (preferably from 10 C to 100 C above 1000 C) for a
specific duration (for example, from approximately several
hours to approximately 24 hours).
[0013]
Moreover, in the method to diffuse and permeate a creep
reinforcement material into the heat-resistant metal member
10 according to the present invention, in order to restrict
thermal expansion of the heat-resistant metal member 10
toward the outside in the length direction thereof (in
directions toward the ends of the heat-resistant metal member
10) occurring when the heat-resistant metal member 10, which
has been coated or thermally sprayed with the creep
reinforcement material, is covered by the heat-resistant
covering member 30 and heated by the heater 40, the
heat-resistant metal member 10 may be secured in sections not
being heated by the heater 40, by, for example, two clamps
so as to sandwich the section being heated by the heater 40.
In cases in which the section heated by the heater 40 is
small compared to the overall heat-resistant metal member 10,
there is no need to secure the heat-resistant metal member
10 in sections not being heated by the heater 40 with clamps
or the like, since thermal expansion toward the outside in
the length direction of the heat-resistant metal member 10
in the section being heated by the heater 40 is restricted
by the sections not being heated by the heater 40.
[0014]
Examples of the heat-resistant metal of the member 10
include 0.3Mo steel, 0.5Mo steel, 0.5Cr-0.5Mo steel,
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1Cr-0.2Mo steel, 1Cr-0.5Mo steel, 1.25Cr-0.5Mo steel,
2.25Cr-lMo steel, 5Cr-0.5Mo steel, 7Cr-0.5Mo steel, 9Cr-lMo
steel, 0.3Cr-Mo-V steel, 0.5Cr-Mo-V steel, 9Cr-Mo-V steel,
12Cr-Mo-V steel, 1Cr-1.25Mo-0.25V steel, 90r-lMo-W steel,
SUS304, SUS304L, SUS316, SUS316L, SUS316TI, SUS317, SUS321,
SUS347H, SUS310S, Super304, SUS904L, NCF600, NCF601, NCF800,
and NCF800H; however, there is no limitation thereto. Any
known material used for members employed in thermal or nuclear
power generation units or other high temperature plants may
be employed as the heat-resistant metal for the member 10.
[0015]
There are no particular limitations to the creep
reinforcement material, as long as it contains an element
which has a melting point of 1000 C or greater and in which
precipitation strengthening and solid solution strengthening
occur upon heating to a temperature of 1000 C or greater so
as to enable creep strength to be enhanced. Thus, for example,
according to the substance of the heat-resistant metal member
10, the creep reinforcement material may contain any one or
a plurality of elements appropriately selected from B (boron) ,
W (tungsten), Cr (Chromium), Mo (molybdenum), Nb (niobium),
V (vanadium), Hf (hafnium), Zr (zirconium), Ti (titanium),
Cu (copper), and Co (cobalt). In cases in which the creep
reinforcement material is coated on the surface of the
heat-resistant metal member 10, powdered creep reinforcement
material may be employed as it is, or a coating agent of the
creep reinforcement material in a liquid form or paste form
using a binder, solvent, adhesive or the like may be employed.
In cases in which the creep reinforcement material is
thermally sprayed on the surface of the heat-resistant metal
member 10, for example, a known thermal spray method may be
appropriately employed, such as a plasma spraying method
using powdered creep reinforcement material. Note that
coating or thermally spraying of the creep reinforcement
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material on the surface of the heat-resistant metal member
may be performed over the entire outer peripheral surface
of the heat-resistant metal member 10 as in the present
embodiment, or may be performed on a part of the surface of
5 the heat-resistant metal member 10.
[0016]
There are no particular limitations to the heat-resistant
covering member 30, as long as it is capable of covering the
section 25 coated or thermally sprayed with the creep
10 reinforcement material so as to make contact with the section
25, as long as it is made from a heat-resistant material that
restrains thermal expansion in the section 25 in the direction
toward the outer periphery of the heat-resistant metal member
10 occurring when heated to the heating temperature mentioned
above, and is able to maintain the approximate profile of the
heat-resistant metal member 10 at the section 25. A material
having a lower thermal expansion coefficient than the
heat-resistant metal member 10 at temperatures of the heating
temperature mentioned above or greater is preferably employed
for the heat-resistant covering member 30. In cases in which
the heat-resistant covering member 30 is configured from a
heat-resistant material different from that of the
heat-resistant metal member 10, yet having a thermal
expansion coefficient of about the same as the heat-resistant
metal member 10, or from a heat resistant material having a
higher thermal expansion coefficient than the heat-resistant
metal member 10, in order to restrain the thermal expansion
of the heat-resistant covering member 30 occurring when
heated to the heating temperature mentioned above, the outer
periphery of the heat-resistant covering member 30 may be
secured by a member of a heat-resistant material having a lower
thermal expansion coefficient than the heat-resistant metal
member 10 at or above the heating temperature mentioned above,
so as to maintain the profile of the heat-resistant covering
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member 30.
[0017]
Examples of the heat-resistant material of the
heat-resistant covering member 30 include ceramics such as
5 alumina, zirconia, aluminum nitride, silicon carbide,
silicon nitride, cordierite, sialon, zircon, andmullite, and
alloys such as Alloy 903, Alloy 909, and HRA 929.
[0018]
The heat-resistant covering member 30 is, for example,
10 of a cord, plate, or clamp shape. Securing of the above may
be performed by, for example, wrapping a cord-shaped or
plate-shaped heat-resistant covering member 30 around the
outer periphery of the heat-resistant metal member 10 at the
section 25 coated or thermally sprayed with the creep
reinforcement material, by attaching a clamp-shaped
heat-resistant covering member 30 to the outer periphery of
the heat-resistant metal member 10 at the section 25 coated
or thermally sprayed with the creep reinforcement material,
or by attaching a heat-resistant covering member 30 formed
in a plate shape or the like to the outer periphery of a
heat-resistant metal member 10 at the section 25 coated or
thermally sprayed with the creep reinforcement material using
fasteners, such as clamps or screws. In the present
embodiment, the heat-resistant covering member 30 is made
from fittings including two substantially semi-circular arc
cross-section shapes. The heat-resistant covering member 30
is then secured to the surface of the heat-resistant metal
member 10 using threaded members 35 attached to flanges of
these fittings, such that the inner face of the fittings
contact the outer periphery of the heat-resistant metal
member 10 at the section 25 coated or thermally sprayed with
the creep reinforcement material. The threaded members 35
are manufactured, for example, from the same material as the
heat-resistant covering member 30.
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[0019]
The heating temperature of the heat-resistant metal
member 10 coated or thermally sprayed with the creep
reinforcement material is not particularly limited, as long
as it is a temperature of 1000 C or greater. Preferably the
heat-resistant metal member 10 is heated at a temperature of,
or greater than, an A3 transformation point of the component
of the heat-resistant metal material of the member 10 or the
creep reinforcement material having the highest A3
transformation point (preferably from 10 C to 100 C above
1000 C) for a specific duration (for example, from
approximately several hours to approximately 24 hours) . Note
that although the present embodiment employs, as a heating
device, the high frequency heater 40, which is capable of
heating the heat-resistant metal member 10 coated or
thermally sprayed with the creep reinforcement material, from
the outer periphery thereof, there is no particular
limitation thereto, as long as a heating device capable of
heating the heat-resistant metal member 10 at the section 25
coated or thermally sprayed with the creep reinforcement
material.
[0020]
The product of diffusing and permeating the creep
reinforcement material into the heat-resistant metal member
10 by the method described above is useful as a heat-resistant
metal member with enhanced creep strength due to the creep
strength being enhanced as described above.
Reference Signs List
[0021]
10 heat-resistant metal member
20 weld
25 section coated or thermally sprayed with creep
reinforcement material
30 heat-resistant covering member
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35 threaded member
40 high frequency heater
