JP2000273573A - Corrosion resistant and wear resistant alloy and apparatus using the alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the corrosion of eutectic carbides of a Co base alloy (so with Ni base and Fe base alloys) used for the sliding part of an apparatus and a valve seat which have been the cause of increasing the amt. of radiation in a nuclear power plant. SOLUTION: A Co base alloy (so with Ni base and Fe base alloys) used for the sliding part of an apparatus and the valve seat of a valve is subjected to plastic working, by which, in eutectic carbides and the base material part of a cast structure composing the Co base alloy (so with Ni base and Fe base alloys), the eutectic carbides are spheroidized and granulated, so that the corrosion of the eutectic carbides can be limited to the surface, and the corrosion is stopped to the limited range of the surface. Therefore, the corrosion is suppressed, the suppression of the frequency of the disassembly and inspection is made possible, furthermore, in the Co base alloy, by the suppression of the amt. to be corroded, the amt. of Co to be eluted reduces, and the amt. of Co brought into a reactor vessel can also be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion-resistant and wear-resistant alloy and a device using the alloy.

[0002]

2. Description of the Related Art Valves, such as safety valves, have a high flow velocity in a valve seat during actual operation, so as to prevent erosion damage and to prevent galling during operation of the valve. High hardness Co-base alloy / Ni-base alloy / Fe with excellent wear performance
Valve seats made of base alloys and other surface-welded alloys for corrosion and wear resistance (so-called valve seats using corrosion- and wear-resistant alloys)
Is used.

However, in recent years, injection of hydrogen peroxide solution or the like has been performed in plant equipment such as turbine power generation equipment for the purpose of water quality adjustment. As a result, the amount of dissolved oxygen downstream of the injection point has increased. A eutectic carbide and a cast structure base that constitute a corrosion- and wear-resistant alloy such as a Co-based alloy that has been laid up for corrosion and wear resistance, which is installed to prevent galling and erosion on the valve seat surface of the valve In the material part, eutectic carbide is selectively damaged by corrosion, and if there is a flow, there are events such as corrosion damage of eutectic carbide, base material of cast structure falling off, and erosion occurring. It has been reported.

[0004] A related article is "Thermal Nuclear Power Generation"
Vol.30-5 Treatment of boiler water with oxygen and ammonia in steam system of thermal power plant, damage to machinery 1982-
No. 2 Operating Experience with Combined Operating Methods at VEW Gerstein Power Station "and" Materials and Environment Vol.4
7, No. 3 Effect of heat treatment conditions on intergranular corrosion of cobalt-based alloy welds ".

[0005]

[0004] Valves including safety valves have a high hardness based on a high hardness Co-based alloy having excellent corrosion and wear resistance in order to prevent the erosion damage due to the high flow rate of the valve seat during actual operation.・ A valve seat with a surface welded alloy such as a Ni-based alloy or Fe-based alloy is used. Also, in order to prevent galling during operation of the valve, the surface of the guide that guides the valve body and the inner surface of the cage have corrosion resistance and wear resistance. A valve box is used in which a Co-based alloy, a Ni-based alloy, an Fe-based alloy, etc., which are excellent in hardness and are hardened, are used.

However, when a valve seat made of a corrosion-resistant and wear-resistant alloy such as a Co-based alloy is used in a high-temperature and high-pressure water / steam atmosphere containing a large amount of dissolved oxygen, the base material layer of the casting structure is cast into a mesh. The network-like eutectic carbide in the corrosion-resistant and wear-resistant alloy consisting of the eutectic carbide enclosing the base material layer of the structure is selectively corroded by dissolved oxygen in the fluid, and the surface roughness of the valve seat becomes severe. At the same time, as a result, the erosion resistance of the corrosion-resistant and wear-resistant alloy is improved because the base portion of the cast structure, which has lost its holding by the eutectic carbide network due to corrosion and fall-off of the eutectic carbide, easily falls off due to the flow. (FIG. 3). As a result, valves used in an atmosphere containing a large amount of dissolved oxygen have a reduced safety performance due to the surface roughness of the valve seat of the safety valve, and the upstream valve seat and the check valve of the gate valve are corroded by eutectic carbide. The effect is only the surface roughness due to the falling off, but the erosion proceeds due to the flow in the downstream valve seat of the gate valve, and the leakage resistance deteriorates. As a result, the erosion of the valve seat progresses and the leakage resistance deteriorates, and the erosion of the cage guide progresses, resulting in a change in control characteristics and a change in operation characteristics. As a result of the occurrence of these events, the frequency of overhaul of the valve increases, and as a result, the maintainability of the plant decreases.

In particular, in the case of nuclear power generation equipment, as a result of the occurrence of the above-mentioned events, the sliding parts in contact with the reactor water and the valves of the system equipment for supplying cooling water into the reactor are used for these parts. The corrosion and wear resistant alloys of Co-based alloys
By erosion, it scatters and diffuses in the system,
These escaping Cos are activated in the reactor to become Co isotopes having a long half-life, and diffuse into the system, thereby increasing the radiation dose of the system equipment. The present invention suppresses the continuous corrosion of the eutectic carbide in the corrosion-resistant and wear-resistant alloy, thereby suppressing the deterioration of the erosion resistance of the surface-welded alloy, and provides more maintainable safety valves, gate valves, and check valves. In addition to supplying valves such as valves, globe valves, and cage valves, the present invention aims to improve the maintainability of thermal and nuclear power plants and to reduce the exposure of workers to nuclear power plants.

[0008]

The first means is a Co-based or Ni-based material used as a wear-resistant material such as a sliding portion of a device or a valve seat of a valve.
Of the base material and eutectic carbide of the cast structure that constitute the surface-welded alloy such as corrosion- and wear-resistant alloys such as iron-based and Fe-based alloys, the eutectic carbide that is continuously distributed in a mesh shape is discontinuous as particles or spheres. By improving the wear resistance and erosion resistance, the increase in the frictional resistance of the sliding parts of the equipment is suppressed, especially in the case of valves, the reduction in leakage resistance due to the roughening of the valve seat surface. A device and a valve characterized by suppressing.

The second means is that the valve seat of the safety valve is based on Co, Ni or Ni.
Of the base material and eutectic carbide of the cast structure that constitute the surface-welded alloy such as corrosion- and wear-resistant alloys such as iron-based and Fe-based alloys, the eutectic carbide that is continuously distributed in a mesh shape is discontinuous as particles or spheres. This is a safety valve having a valve seat using a valve seat material in which eutectic carbide is made into a granular or spherical form by performing plastic working such as forging and rolling in order to make it into a steel sheet.

The third means is that the valve seat of the gate valve and the check valve is made of Co.
Plastic processing such as forging and rolling in order to discontinue the eutectic carbide that is continuously distributed in a mesh form of surface-welded alloys such as corrosion- and wear-resistant alloys such as Ni-base, Ni-base, and Fe-base alloys into grains or spheres Accordingly, the present invention provides a gate valve and a check valve having a valve seat using a valve seat material in which the eutectic carbide is reduced in the corrosion or wear resistant alloy and the eutectic carbide is granular or spherical.

The fourth means is a valve seat of a ball valve, a cage valve or the like.
Eutectic carbides are formed by plastic working such as forging and rolling in order to discontinue the eutectic carbides distributed continuously in the form of a network of corrosion-resistant and wear-resistant alloys such as o-bases, Ni-bases, and Fe-bases into grains or spheres. A ball valve and a cage valve having a valve seat and others using a spherical valve seat material.

Fifth means is to form Co-based, Ni-based, Fe-based eutectic carbide particles or spheres by plastic working such as forging and rolling.
After machining a base alloy or other corrosion- or wear-resistant alloy material into the shape of a valve seat, cage, or guide, electron beam welding, welding with a corrosion-resistant or wear-resistant alloy welding rod, brazing of silver braze, diffusion welding, etc. A safety valve that manufactures a valve by bonding it to a base material,
It is a throttle valve such as a gate valve, a globe valve, and a cage valve.

The sixth means is to improve the maintainability of the power generation equipment by using equipment and valves using the corrosion-resistant and wear-resistant alloy material of the Co-based alloy in which the eutectic carbide is granular or spherical as the nuclear power generation equipment. Nuclear power plant.

According to the first means, in the normal state, the eutectic carbides are Co-base, Ni-base, Fe-base, which are continuous in a network.
Corrosion- and wear-resistant alloys such as bases have Co-bases with discontinuous eutectic carbides because the eutectic carbides change into granular or spherical forms.
Corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based and Fe-based due to corrosion of eutectic carbides due to dissolved oxygen generated by injection of hydrogen peroxide water etc. By suppressing damage, Co-based, Ni-based, F-based
The frequency of maintenance of equipment and valves is reduced by suppressing the increase in frictional resistance of sliding parts of equipment due to the corrosion and wear-resistant alloys such as e-base alloys, and the reduction in leakage resistance due to the roughness of valve seat surfaces. Equipment and valves with excellent maintenance performance can be supplied.

According to the second means, the corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based, and Fe-based alloys used for the valve seat of the safety valve normally have a eutectic carbide in a mesh shape in a normal state. The surface area of the eutectic carbide is reduced by plastic working such as forging and rolling, and the eutectic carbide is changed into a granular or spherical form to become a discontinuous eutectic carbide, which is caused by injection of hydrogen peroxide water or the like. By suppressing corrosion damage of corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based and Fe-based alloys due to corrosion of eutectic carbides due to dissolved oxygen, corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based and Fe-based alloys can be reduced. It is possible to suppress the deterioration of the valve seat seal and the leakage resistance performance due to the roughening, thereby suppressing the drift of the set pressure, thereby reducing the maintenance frequency of the safety valve and supplying a safety valve having excellent maintenance performance.

According to the third means, in the normal state, corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based, and Fe-based alloys in which eutectic carbides are continuously formed in a network are formed by plastic working such as forging and rolling. The surface area of the eutectic carbide is reduced, and the eutectic carbide becomes discontinuous by changing to a granular or spherical form, and becomes a Co-base, Ni by corrosion of the eutectic carbide due to dissolved oxygen generated by injection of hydrogen peroxide water or the like. By reducing the corrosion damage of corrosion- and wear-resistant alloys such as Fe-based and Fe-based, Co-based, Ni-based, Fe-based
By suppressing the deterioration of the valve seat seal and leakage resistance performance due to the corrosion of the corrosion-resistant and wear-resistant alloy of the base, etc., the base of the eutectic carbide in the valve seat of the check valve and the upstream valve seat of the gate valve is corroded. ,
Suppression of deterioration of valve seat seal and leak resistance due to corrosion of corrosion-resistant and wear-resistant alloys such as Ni-based and Fe-based alloys, and dissolved oxygen generated by injection of hydrogen peroxide water into the downstream valve seat of the gate valve Of eutectic carbides due to eutectic carbide and Co-based, Ni-based, Fe
By suppressing the deterioration of valve seat seals and leakage resistance due to erosion damage due to the flow of corrosion and wear resistant alloys inside the valve, the frequency of maintenance of gate valves and check valves is reduced, and excellent maintenance performance is achieved. Gate valve can be supplied.

According to the fourth means, in the normal state, corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based and Fe-based alloys in which the eutectic carbides are continuously formed in a network are formed by plastic working such as forging and rolling. The surface area of the eutectic carbide is reduced, and the eutectic carbide becomes discontinuous eutectic carbide by changing into a granular or spherical form. By reducing the corrosion damage of corrosion-resistant and wear-resistant alloys such as Ni-based and Fe-based alloys, the valve seats of ball valves and cage valves can be made of Co-based alloys such as Co-based alloys due to corrosion of eutectic carbide.
Valve seat seal due to roughening of corrosion and wear resistant alloys such as Ni
The frequency of maintenance of the globe valve and the cage valve is reduced by suppressing the decrease in the leak resistance, and the valve body and the cage or the sliding part of the guide for guiding the valve body are made of Co, Ni, or Fe. By suppressing wear damage due to corrosion of corrosion-resistant and wear-resistant alloys, and suppressing deterioration of control characteristics and operating characteristics, a ball valve and a cage valve having excellent maintenance performance can be supplied.

Further, by the fifth means, a valve made of a corrosion-resistant and wear-resistant alloy such as a Co-based, Ni-based, or Fe-based alloy having a granular or spherical eutectic carbide cut out from a forged or rolled material that can be mass-produced. By forming the valve seat with the seat material, safety valve that reduces corrosion damage of the eutectic carbide valve seat due to dissolved oxygen,
Throttle valves such as gate valves, globe valves, and cage valves can be supplied.

According to the sixth means, the scattering and diffusion of Co due to corrosion, erosion and wear of the Co-based alloy used in the valve of the nuclear power plant are suppressed, so that the nuclear power having excellent maintainability is provided. Power plant can be supplied.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a typical SEM image of the surface of a corrosion-resistant and wear-resistant alloy such as Co-based, Ni-based, or Fe-based alloy.
1 of corrosion- and wear-resistant alloys such as Ni-base, Ni-base, and Fe-base
FIG. 3 shows a Cr surface analysis photograph at the same position as that of FIG.

Further, C is subjected to plastic working such as forging and rolling.
S on the surface of corrosion- and wear-resistant alloys such as o-base, Ni-base, and Fe-base
FIG. 4 shows an EM image of Co subjected to plastic working such as forging and rolling.
Fig. 4 of the surface of a corrosion- and wear-resistant alloy such as Ni-base, Ni-base, and Fe-base
FIG. 5 shows a Cr surface analysis photograph at the same position as in FIG.

In FIGS. 1, 2 and 3, the eutectic carbide 1 mainly composed of Cr and C is a base material 2 of a cast structure mainly composed of Co.
And distributed widely on the surface of a surface welded alloy such as a Co-based alloy.

On the other hand, in FIG. 4 and FIG. 5 which are embodiments of the present invention, the eutectic carbide 1 is granular or spherical on the surface of a corrosion-resistant and wear-resistant alloy such as a Co-based alloy with respect to the base 2 of the casting structure. Although the eutectic carbide 1 is uniformly distributed but discontinuous, the eutectic carbide 1 changes from a network to a granular or spherical shape, so that the proportion of the eutectic carbide 1 occupying the surface is reduced.

As shown in FIG.
Corrosion and erosion of the wear-resistant alloy proceeds due to corrosion of the eutectic carbide 1 due to dissolved oxygen, so that the two layers of the base material portion of the casting structure easily fall off.

As shown in the photograph of FIG. 3, a eutectic carbide 1 continuous in a network exists in a corrosion-resistant and wear-resistant alloy such as an ordinary Co-based alloy. As a result, corrosion of the eutectic carbide 1 due to dissolved oxygen and dropping of the two layers of the base material portion of the cast structure occur continuously, resulting in corrosion and erosion in a dissolved oxygen atmosphere.

On the other hand, C which has been subjected to plastic working such as forging and rolling
The eutectic carbides 1 in the corrosion- and wear-resistant alloys such as Co-based and Ni-based alloys such as o-based alloys are present discontinuously in the form of particles or spheres. It is limited to the eutectic carbide 1 on the contacting surface, and the eutectic carbide 1 on the surface does not proceed after corrosion and falling off (see FIG. 7).

In order to confirm the above effects, JIS G
0575 “Sulfuric acid / copper sulfate corrosion test of stainless steel” (Strauss test) was applied. A similar test was conducted on a stellite material, which is a corrosion- and wear-resistant alloy of a Co-based alloy, by Takahisa and Honda (Materials and Environment Vol. 47, Heat treatment conditions affecting grain boundary corrosion of No. 3 cobalt-based alloy welds) Effect) then C
Corrosion- and wear-resistant alloys of o-based alloysStellite materials, which are surface-welded alloys, have been reported to progress in corrosion.However, similar tests were performed on Co-based alloys that had been subjected to plastic processing such as forging and rolling. Almost no etching was observed, no corrosion progressed in the depth direction, and good corrosion resistance was confirmed. The test results are shown in FIG.

[0028]

[Table 1]

From these results, it was found that eutectic carbide 1
, Ni, F
When a corrosion-resistant and wear-resistant alloy such as e-base is used, the corrosion depth can be suppressed to about 1/300 as compared with the conventional case, and the corrosion depth can be reduced by increasing the preheating temperature.

From these results, corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based, and Fe-based alloys in which the eutectic carbides 1 are discontinuously present in a granular or spherical form can suppress corrosion due to dissolved oxygen, and as a result, erosion is also reduced. Can be suppressed.

Further, the preheating temperature of a corrosion-resistant and wear-resistant alloy such as Co-base, Ni-base and Fe-base is usually about 600 ° C.
In the case where a corrosion-resistant and wear-resistant alloy such as a Ni-based or Fe-based alloy is forged and rolled by independently increasing the preheating temperature before joining with the base material, and then joined with the base material, the corrosion-resistant / wear-resistant alloy becomes more resistant to corrosion and wear. The corrosion resistance of the wear alloy can be improved.

Further, in the case where a Co-based corrosion- and wear-resistant alloy in which the eutectic carbide 1 is present in a granular or spherical discontinuity in a nuclear power plant is used, the scattering and diffusion of Co can be suppressed. In a nuclear power plant, Co with a long half-life can be prevented from being activated in the nuclear reactor and diffused into the power generation system of the nuclear power plant, which is effective in improving maintainability by reducing worker exposure.

A wear-resistant and corrosion-resistant overlay welding alloy such as Co-base, Ni-base or Fe-base is overlaid on the valve seat 4 of the safety valve 3 used in the dissolved oxygen atmosphere shown in FIG. In the case of using a corrosion-resistant and wear-resistant alloy such as Co-base, Ni-base, or Fe-base which has been subjected to plastic working, the occurrence of continuous corrosion of eutectic carbide due to dissolved oxygen is prevented, so that the surface of the valve seat 4 Can maintain the soundness of the valve seat and prevent deterioration of the valve seat 4 surface to suppress surface roughening, prevent a decrease in leakage resistance performance, and suppress front leakage.
Suppress drift of set pressure. In the event that a leak occurs, it is possible to suppress the progress of corrosion and erosion, and to suppress an increase in the amount of leak.

A wear-resistant and corrosion-resistant overlay welding alloy such as Co-based, Ni-based, or Fe-based is welded on the valve seat 4 of the gate valve 5 used in the dissolved oxygen atmosphere shown in FIG. In the case of using a corrosion-resistant and wear-resistant alloy such as Co-base, Ni-base, or Fe-base which has been subjected to plastic working such as that described above, the continuous corrosion of eutectic carbide due to dissolved oxygen is prevented, and the base material of the cast structure is formed. By suppressing the falling off of the component layers, the progress of corrosion and erosion of the valve seat 4 can be suppressed, the soundness of the valve seat 4 surface can be maintained, and a decrease in leakage resistance performance can be prevented.

The check seat 6 of the check valve 6 used in the dissolved oxygen atmosphere shown in FIG.
When a corrosion-resistant or wear-resistant alloy such as Co-base, Ni-base, or Fe-base, which has been subjected to plastic working such as forging and rolling, on which the corrosion-resistant overlay welding alloy has been overlaid, eutectic carbide due to dissolved oxygen is used. Of the base material layer of the casting structure is suppressed, thereby preventing the corrosion of the valve seat 4 and maintaining the soundness of the valve seat 4 surface. Prevent drop.

The ball valve 7a, 7b used in a dissolved oxygen atmosphere shown in FIG.
Co-based alloys such as o-based, Ni-based, and Fe-based alloys, which are wear- and corrosion-resistant overlay welding, are subjected to plastic working such as forging and rolling.
-Based, Ni-based, and Fe-based corrosion-resistant and wear-resistant alloys are used to prevent continuous corrosion of eutectic carbide due to dissolved oxygen and to prevent the base material layer of the cast structure from falling off due to flow. The corrosion of the cage 9 and the valve seat 4 in contact with the valve body 10
Suppresses the erosion, maintains the soundness of the valve seat 4 surface, prevents a decrease in leakage resistance performance, and improves controllability.
This has the effect of suppressing a decrease in operating performance.

By using the above valves in combination,
It is possible to suppress the corrosion and erosion of valve seats due to the effect of dissolved oxygen due to the injection of hydrogen peroxide water for the purpose of water quality adjustment, which is performed in plant equipment such as turbine power generation equipment. This has the effect of improving the maintainability of equipment.

In a high-temperature, high-pressure fluid containing a large amount of dissolved oxygen, the equipment and the valve are made of a Co-based, Ni-based,
In order to suppress the increase in frictional resistance of sliding parts and the increase in valve seat leakage due to surface roughness caused by corrosion of eutectic carbides of corrosion- and wear-resistant alloys such as Fe-based alloys, disassembly and inspection are performed every time the plant is stopped. However, when the embodiment of the present invention is applied, the surface roughness of the sliding portion of the device and the valve seat surface of the valve is greatly reduced, the frictional resistance of the sliding portion is increased, and the leakage amount of the valve seat is increased. Can be suppressed, the frequency of disassembly and inspection can be reduced, and the maintainability can be improved.

A safety valve used in a high-temperature, high-pressure steam atmosphere containing a large amount of dissolved oxygen has a problem in that the valve seat surface is roughened due to corrosion of a eutectic carbide of a corrosion-resistant and wear-resistant alloy such as Co-base, Ni-base, or Fe-base. In order to reduce the leak pressure and decrease the set pressure, every time the plant is stopped, an overhaul is performed, but when the embodiment of the present invention is applied, the valve seat surface roughness is significantly reduced. As a result, a reduction in the leak resistance of the valve seat is also suppressed, so that a reduction in the set pressure can be suppressed, so that the frequency of disassembly and inspection can be reduced, and the maintainability can be improved.

Further, the gate valve can suppress erosion of the downstream side valve seat surface, and the throttle valve can suppress erosion of the valve seat surface due to the throttle operation. As a result, the soundness of the valve seat can be maintained for a long period of time. In addition, maintainability can be improved.

Further, since the eutectic carbide of the corrosion-resistant and wear-resistant alloy surface-deposited alloy such as a Co-based alloy can be made into a grain and a spheroid by plastic working such as forging and rolling, the plasticity of forging and rolling can be obtained. By cutting and using the processed corrosion-resistant and wear-resistant alloys such as Co-based, Ni-based, and Fe-based on the valve seat,
Applicable to valves.

Further, in a plant facility such as a turbine power plant using a valve using a Co-based alloy having a spherical or granular eutectic carbide for a valve seat, water quality adjustment performed in the plant facility such as a turbine power plant is performed. Therefore, corrosion and erosion of a valve seat made of a Co-based alloy due to the influence of dissolved oxygen due to injection of hydrogen peroxide solution or the like can be suppressed, and there is an effect of improving maintainability of plant equipment such as turbine power generation equipment.

In particular, in a nuclear power plant, corrosion and debris of a eutectic carbide made of a Co-based alloy such as a sliding portion in contact with reactor water and a valve seat / cage of a valve of a system for supplying cooling water into the reactor, and The outflow of Co in the eutectic carbide into the system
In addition to suppressing the diffusion, it is possible to suppress the falling off of the base portion of the cast structure containing Co as the main component, which has a reduced erosion resistance due to corrosion and falling off of the eutectic carbide, and Co is activated in the nuclear reactor, and the half-life is reduced. By suppressing the diffusion of long Co isotopes into the power generation facility, it is possible to provide a nuclear power plant in which the exposure of workers in the nuclear power plant is reduced more than before.

[0044]

As described above, the corrosion-resistant and abrasion-resistant alloy of the present invention hardly deteriorates in the overall corrosion- and wear-resistant performance due to the corrosion damage of the eutectic carbide part.

Further, according to the device of the present invention, the roughness of the sliding portion of the device due to corrosion damage of the eutectic carbide due to dissolved oxygen in the fluid is small, and the frictional resistance of the sliding portion is favorably maintained. Is done.

Further, according to the valve of the present invention, the roughness of the sliding portion or the valve seat portion of the valve due to corrosion damage of the eutectic carbide due to dissolved oxygen in the fluid is small, and the sliding portion and the valve seat It is possible to reliably maintain the increase in frictional resistance at the part and the prevention of leakage at the valve seat part.

In the nuclear power plant of the present invention, the life of equipment and valves in the plant is extended, and radiation exposure of workers in the plant can be reduced.

[Brief description of the drawings]

FIG. 1 is an SEM photograph showing the metal structure of the surface of a corrosion-resistant and wear-resistant alloy such as a Co-based or Ni-based alloy.

FIG. 2 is an SEM photograph showing a partially enlarged metal structure of FIG.

FIG. 3 is an SEM photograph showing a metal structure expressed by a surface analysis of a corrosion-resistant and wear-resistant alloy such as a Co-based or Ni-based alloy.

FIG. 4 is an SEM photograph showing the metal structure of the surface of a corrosion-resistant and wear-resistant alloy such as a Co-based or Ni-based alloy subjected to plastic working.

FIG. 5 shows a metal structure expressed by a surface analysis of the surface of a corrosion-resistant and wear-resistant alloy such as a Co-based or Ni-based alloy.
M photo.

FIG. 6 is a schematic diagram showing the repeated progress of damage caused by dissolved oxygen in a corrosion-resistant and wear-resistant alloy such as a Co-based or Ni-based alloy.

FIG. 7 is a schematic diagram showing the state of suppressing damage caused by dissolved oxygen of a corrosion-resistant and wear-resistant alloy such as a Co-based or Ni-based alloy subjected to plastic working.

FIG. 8 is an SEM photograph showing a metal structure obtained by a Strauss test result of a Co-based alloy subjected to plastic working such as forging and rolling.

FIG. 9 is a longitudinal sectional view of a safety valve.

FIG. 10 is a longitudinal sectional view of a gate valve.

FIG. 11 is a longitudinal sectional view of a check valve.

FIGS. 12A and 12B are longitudinal sectional views of various throttle valves, in which FIG. 12A shows a globe valve, FIG. 12B shows a Y-globe valve, and FIG. 12C shows a cage valve.

[Explanation of symbols]

1: eutectic carbide, 2: base material of cast structure, 3: safety valve,
4 ... valve seat, 5 ... gate valve, 6 ... check valve, 7a, 7b ... ball valve, 8 ... cage valve, 9 ... cage, 10 ... valve body.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16K 25/04 F16K 25/04 G21D 1/00 G21D 1/00 V W (72) Inventor Yoshiteru Chiba Ibaraki Hitachi Kyowa Engineering Co., Ltd. (72) Inventor Makoto Kumagai 3-1-1 Sachimachi, Hitachi-shi, Ibaraki Pref. Hitachi, Ltd. Hitachi Plant Hitachi Plant (72) Inventor Ogawa Hirohiro Ibaraki 3-1-1, Sachimachi, Hitachi City, Hitachi, Ltd.Hitachi Plant, Hitachi, Ltd. (72) Inventor Akira Sakamoto 3-1-1, Sachimachi, Hitachi City, Ibaraki Prefecture, Hitachi, Ltd. Inventor Noriyuki Onaka 3-10-2 Bentencho, Hitachi City, Ibaraki Prefecture Inside Hitachi Kyowa Engineering Co., Ltd. (72) Inventor Hiroyuki Shinohara Sachimachi, Hitachi City, Ibaraki Prefecture Eyes No. 1 No. 1 stock company Hitachi, Ltd. Hitachi in the factory

Claims (7)

[Claims] An alloy having a cast structure base material and a eutectic carbide, wherein said eutectic carbide is formed into a plurality of particles or a plurality of spheres to form a non-continuous distribution of said eutectic carbide.
Wear resistant alloy. 2. The corrosion-resistant and wear-resistant alloy according to claim 1, wherein the alloy having the cast structure base material and the eutectic carbide is subjected to plastic working by forging or rolling to make the eutectic carbide non-continuous distribution. 3. An apparatus using the corrosion-resistant and wear-resistant alloy according to claim 1 for a sliding portion. 4. A valve using the corrosion-resistant and wear-resistant alloy according to claim 1 for a sliding portion. 5. A valve using the corrosion-resistant and wear-resistant alloy according to claim 1 for a valve seat. 6. A valve according to claim 5, wherein the corrosion-resistant and wear-resistant alloy according to claim 1 is bonded or welded to a valve body or a valve box at a position of a valve seat. 7. A cobalt-based corrosion- and wear-resistant alloy having a granular or spherical eutectic carbide formed on a sliding portion of a device that comes into contact with reactor water of a nuclear power plant, a valve seat of a valve, or a cage of a valve. Nuclear power plant.