JP2840191B2 - Equipment using cobalt-free alloy material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cobalt-free or cobalt (Co) -free alloy material, and more particularly to an apparatus such as a valve having relatively movable components such as a valve body and a valve box. Things.

[0002]

2. Description of the Related Art Conventionally, as a material for a valve seat, a Co-based material has been used in order to impart abrasion resistance and corrosion resistance to the valve material. However, for example, in a coolant system of a nuclear power plant, a high-temperature and high-pressure fluid such as water is used, and the valve is exposed to the high-temperature and high-pressure water. In the method, Co is eluted from the metal surface into the furnace water by the corrosive action of the high-temperature and high-pressure water. In addition, when the valve body slides with respect to the valve box valve seat with opening and closing of the valve, a small amount of Co abrasion powder is generated, which is also brought into the reactor water.

[0003] These Cos enter the reactor core, are irradiated with neutrons, are activated and are converted into the isotope Co60, which circulates through the coolant system and adheres to the pipes, valves and other equipment, so that the entire nuclear power plant Therefore, the radiation exposure level of the workers may be increased at the time of periodic inspection and the like. Therefore, the appearance of a valve seat that does not require the use of Co has been desired in order to reduce the exposure dose and to limit the use of rare metals that are valuable as industrial resources.

[0004]

As a cobalt-free material that does not use Co, conventionally, Ni-based and Fe-based materials have been used.
Although base alloys have been employed, these alloys have a problem that they are inferior in either abrasion resistance or corrosion resistance as compared with Co base alloys.

[0005] For example, R NiC, a Ni-based cladding material commonly called colmonoy, specified in the specification of AWS (American Welding Society) (A5.11-54).
In rB, carbon C: 0.4-0.8%, silicon Si: 3
-5%, chromium Cr: 10-16%, boron B: 2-4
%, Fe: 3 to 5%, and the balance being Ni, but in this alloy, boron B is contained in a relatively large amount of 2 to 4%. It was known that cracks occurred in the embossed layer.

An alloy obtained by improving this colmonoy material to reduce the content of boron B is disclosed in Japanese Patent Application Laid-Open No. 55-31127. In this alloy, boron B: 0.05 to 1.5%, silicon Si: 3 to 7%,
Chromium Cr 10-15%, Carbon C: 0.05-1.5%
The balance was Ni, but the wear resistance was insufficient even though cracking during welding was reduced due to the reduction in boron B.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art. Another object of the present invention is to provide an apparatus excellent in both corrosion resistance and corrosion resistance.

[0008]

In order to achieve the above-mentioned object, the present invention according to claim 1 has at least two components made of an alloy, one of which is positioned relative to the other. In the device which is movable in a movable manner, the constituent members are a first alloy material and a second alloy having different hardness, each of which is composed of a Ni-Cr-Si-Fe-W-based cobalt-free Ni-based alloy.
The first alloy material is formed of an alloy material, and the chemical composition of the first alloy material is Cr: 5 to 15%, Si: 3 to 7%, and Fe: 10
Super to 40%, W: 1 to 4%, B: 1% or less, C: 1% or less, Ni: balance, and the chemical composition of the second alloy material is C
r: 15 to 20%, Si: 3 to 7%, Fe: 35% or less, W: 1 to 4%, Sn: 0.5 to 1.0%, B: 1% or less, C: 1% or less, Ni: characterized by the balance. As a device to which the present invention is applied, a valve provided with a valve element that slides under the action of hydraulic pressure, such as a gate valve, is preferable.

According to another aspect of the present invention, in an apparatus in which one of the constituent members is relatively movable with respect to the other, one and the other of the constituent members are each Cr: 5 to 5.
15%, Si: 3 to 7%, Fe: more than 10 to 40%, W:
1 to 4%, B: 1% or less, C: 1% or less, Ni: remaining alloy material or Cr: 15 to 20%, Si: 3 to 7
%, Fe: 35% or less, W: 1-4%, Sn: 0.5-0.5%
An apparatus using a cobalt-free alloy material, characterized by being formed from an alloy material of 1.0%, B: 1% or less, C: 1% or less, and Ni: balance.

[0010]

[Action] The chemical composition of a cobalt-free alloy material is Cr:
5 to 15%, Si: 3 to 7%, Fe: more than 10 to 40%,
When W is 1 to 4%, B is 1% or less, C is 1% or less, and Ni is the balance, an alloy material excellent in both wear resistance and corrosion resistance can be obtained. This is because Cr: 15-20%, S
i: 3 to 7%, Fe: 35% or less, W: 1 to 4%, S
n: 0.5 to 1.0%, B: 1% or less, C: 1% or less, N
i: The same applies to the remaining cobalt-free alloy material.

When such an alloy material is used for a sliding portion of a device such as a valve which is exposed to high temperature and pressure as in a nuclear power plant, for example, it has good wear resistance and corrosion resistance.
A highly reliable device can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. In FIG. 1, a main part of a motor-driven valve device having a valve seat according to the present invention, that is, a gate valve is generally indicated by reference numeral 10. In FIG. 1, a gate valve (valve device) 10 includes a hollow valve box 11 that defines a flow path 11a of a fluid that flows when the valve is opened as shown by an arrow 17 and a flow path 11a. As shown in the figure, a wedge-shaped valve element 12 which can move up and down in the direction of an arrow indicated by reference numeral 15 is provided between a valve closing position for shutting off and a valve opening position (not shown) for partially or entirely opening. ing. Valve body 1
The lower end of the valve stem 12a is connected to 2 as is well known, and the valve body 12 can be moved as described above by operating the valve stem 12a.

The sliding surface between the valve box 11 and the valve body 12 is generally called a valve seat, and in FIG.
Reference numeral 14 denotes an annular valve seat (constituent member) which is a sliding surface of
Further, the annular valve seat portion (constituent member) which is the sliding surface of the valve element 12 is indicated by reference numeral 13. Valve body 12
When the valve is fully closed, a fluid pressure acts on the side surface as indicated by an arrow 16, and if it is attempted to open and close the valve body 12 in the arrow direction 15 against this pressure, each valve seat portion 1
Wear occurs on 3,14.

FIG. 2 shows the details of the valve seats 13 and 14 described above. According to the present invention, the material of the valve body valve seat portion 13 and the valve box valve seat portion 14 are both Cr-Si-Fe.
Although a -W-based Ni-based alloy is used, the first material forming one of them has a different chemical composition and hardness from the other second material. Specifically, one of the valve body valve seat portion 13 and the valve box valve seat portion 14 has Cr: 5 to 15% and Si: 3
７7%, Fe: more than 10〜40%, W: 1４4%, B: 1
%, C: 1% or less alloy material (1), the other is Cr: 15-20%, Si: 3-7%, Fe: 3
5% or less, W: 1-4%, Sn: 0.5-1.0%, B:
It is preferable to form the alloy material (2) of 1% or less and C: 1% or less. Either the valve body valve seat 13 or the valve box valve seat 14 may be made of the alloy material (1).

The present inventor conducted experiments on various test material alloys as alloy materials used for the valve seats of the valve box 11 and the valve body 12. Table 1 attached at the end of the detailed description of the invention in this specification shows the chemical composition and hardness of each alloy tested by combining various first and second materials (soft-side alloy a and hard-side alloy b). , Hardness difference and sliding test results.

In order to build up the test material alloys shown in Table 1 as the valve seats 13 and 14, the alloys are melted by using a well-known high-frequency vacuum melting furnace and then pulverized by water or gas atomization. Then, a powder of the test material alloy was manufactured. The particle size of the powder is +
It was in the range of 70 to +210 mesh.

Using this powder, a well-known plasma powder build-up welding method is used to form S25C and SCPH2 which are a kind of carbon steel.
(Valve diameter: 145 mm) and an actual valve body and valve seat, that is, a valve body and valve seat actually used (diameter:
(In the case of 650 mm) on which a two-layer build-up welding was performed, the abrasion test body, the valve body and the valve seat were processed and rubbed with a 600-mesh paper file before the test. Under the following differential pressure load conditions, a sliding wear test was performed after taking care not to leak water.

The abrasion test was performed on a test piece having a diameter of 145 mm in water at room temperature and in saturated water at 300 ° C. using a mechanism simulating the sliding state of the gate valve.
The test was performed with a differential pressure of 88 kgf / cm ² loaded.
Incidentally, the valve seat pressure under the condition that this differential pressure is applied is calculated by 2
0 Kgf / mm ² .

For the actual valve body and valve seat, for example, a valve having a diameter of 650 mm which is a maximum diameter valve for a nuclear power plant (specifically, a pressure of 152 kg at a temperature between room temperature and 300 ° C.)
f / cm ² ) and a sliding pressure of 87.9 kgf / cm ² in water at room temperature.
The test was performed at 0 mm / min. The valve seat pressure when this differential pressure was applied was calculated to be 15 kgf / cm ² .
In Table 1 showing the test results, a test in which the number of slides is 100 or less indicates that significant leakage occurred at that time and the test was stopped.

After the test, the roughness of the sliding surface of the test piece was measured by a well-known method, and a sample having a sliding mark depth of 1 μm RA or less was evaluated as good. The roughness of 1 μm RA is such that the valve seat surface can be easily restored by the rubbing operation in the valve maintenance operation. As can be seen from Table 1, in the test body, valve body and valve seat to which the present invention was applied,
The surface roughness after 100 times of sliding was all 1 μm RA or less, demonstrating the effectiveness of the present invention.

On the other hand, even if the chemical composition and hardness are almost the same, those having a hardness difference of 3 or less in HRC, when applied to a sliding part, cause leakage at the initial stage of sliding, and Had a roughness of 1 μm RA or more and poor slidability. However, when the present invention is applied to a sliding portion such as a guide portion (see FIG. 3), it is not necessary to maintain a strictly sealed state as compared with a valve seat, and some wear is allowed. It is not necessary to provide such a hardness difference.

As apparent from the above description, according to the present invention, one of the valve body valve seat portion 13 and the valve box valve seat portion 14 has Cr: 5 to 15%, Si: 3 to 7%, Fe: 10
It is formed from an alloy material (1) having an ultra-high 40%, a W: 1-4%, a B: 1% or less, and a C: 1% or less.
-20%, Si: 3-7%, Fe: 35% or less, W: 1
-4%, Sn: 0.5-1.0%, B: 1% or less, C: 1
% Or less of the alloy material (2). The hardness difference between the two alloy materials is 5 or more (Vickers hardness H) in Rockwell HRC from the viewpoint of preventing seizure and galling.
v70 or more).

Here, the grounds for selection of the ratio of each chemical composition will be described. Generally, Cr is commonly used to improve corrosion resistance. However, the alloy materials (1) and (2) used according to the present invention are essentially excellent in corrosion resistance because they are Ni-based, and do not require much Cr. For example, the Type D-3 niresist according to the American Society for Testing and Materials (ASTM) is Ni: 28-32.
%, Si: 1.5 to 3%, Cr: 2.5 to 3%, and the balance is substantially an Fe-based alloy, but is 0% in the steam at 133 to 221 ° C. of the nuclear power plant. .0
Shows the amount of corrosion of 25mm / year or less.
Since it shows almost the same corrosion resistance as US403, if the cladding material of the present invention contains 5% or more, sufficient corrosion resistance is exhibited as a valve seat material for a nuclear power plant. But,
Since Cr is an element that improves the oxidation resistance of metal, it prevents oxidation of wear powder generated by sliding of the valve seat.
When r is added in an amount of 20% or more, a metallic strip is formed, which causes seizure or galling on the sliding portion. Therefore, the range of Cr is preferably 5 to 20%.

Next, silicon Si is necessary to maintain hardness and wear resistance, but if added in a large amount, toughness is reduced and welding workability is deteriorated.
It should be set as%.

Fe lowers the hardness of the overlay to improve weldability. In addition, abrasion powder which is easily oxidized at the time of sliding is generated to prevent seizure and galling, but when added in a large amount, the corrosion resistance of the alloy is reduced. For this reason, Fe is added to the soft side alloy in an amount of more than 10 to 40%, and the Fe content of the hard side alloy is limited to 35% or less. Thereby, the difference in Rockwell hardness HRC becomes 5 or more. When the first and second alloy materials are welded by plasma powder overlay to a valve seat having a diameter of about 650 mm, the relationship between the Fe content and the hardness is as shown in FIG. Therefore, when Fe of the second alloy material is 40%, a necessary hardness difference can be obtained if Fe of the first alloy material is 35% or less.

Tungsten W increases the hardness to maintain abrasion resistance, and generates lubricating tungsten oxide during sliding to prevent seizure and galling. Add.

Tin Sn is a soft metal and forms a lubricating thin film during sliding to prevent seizure and galling.
If added in a large amount, the toughness is reduced and the weldability deteriorates, so 0.5 to 1% is added only to the hard alloy.

Finally, boron B and carbon C are contained as impurities, but if they are too much, welding workability is deteriorated. Therefore, the content is limited to 1% or less to prevent cracking during welding and heat treatment. Note that B and C both have the effect of increasing the hardness of the overlay, but in order to maintain the wear resistance, S
Since it is desirable to increase the hardness by i, the content as an impurity is limited in the present invention as described above.

The case where the present invention is applied to the valve seat portion of the gate valve has been described above. However, the present invention is not limited to this embodiment, and the present invention is not limited to this embodiment. The present invention can be similarly applied to a check valve in which the seat does not slide. In addition, the present invention can be suitably used for a sliding portion or a guide portion of any device in which sliding occurs, in addition to the valve device (for example, shafts and bearings of various devices). The present invention can be similarly applied to an appropriate component that requires high wear resistance and corrosion resistance for use, and this component does not necessarily need to be a sliding member.

For example, FIG. 3 is a cross-sectional view of the valve device 10 of FIG. 1 cut along a plane perpendicular to the paper surface. Although the guide portions 18 and 19 are formed to assist, the guide portions 18 and 19 as well as the valve seat may be formed of an alloy material having the above-described composition.

When the Ni-based alloy according to the present invention is built up on the valve seat, the sliding portion or the guide portion as described above, it is not the plasma powder build-up welding as described above, but powder spraying or the like.
It may be joined or manufactured using TIG welding or gas welding using a welding rod, powder metallurgy, and in some cases, cast.

[0032]

As described above, according to the present invention, high abrasion resistance and corrosion resistance can be obtained, so that seizure, galling, and cracking do not occur, and they can be suitably used under high temperature and high pressure. It is possible to provide a highly reliable device.

[Table 1]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a gate valve having a valve seat according to the present invention.

FIG. 2 is a sectional view of a main part of the gate valve of FIG.

FIG. 3 is a schematic sectional view of the gate valve of FIG. 1 cut along a plane perpendicular to the paper surface.

FIG. 4 is a graph showing the relationship between Fe content and hardness.

[Explanation of symbols]

Reference numeral 10: gate valve (valve or device), 11: valve box, 12: valve body, 13: valve body valve seat (component), 14: valve box valve seat (component), 18: valve body side guide Part (component),
19: guide part (component) on the valve box side.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-276038 (JP, A) JP-A-55-31127 (JP, A) JP-A-57-164950 (JP, A) (58) Field (Int. Cl. ⁶ , DB name) C22C 19/00-19/05

Claims (3)

(57) [Claims] An apparatus having at least two alloy components, one of which is movable relative to the other, wherein each of the components is Ni-Cr-S
The first alloy material is made of an i-Fe-W-based cobalt-free Ni-based alloy having different hardnesses, and has a chemical composition of Cr: 5.
１５15%, Si: 3 ％ 7%, Fe: more than 10〜40%,
W: 1 to 4%, B: 1% or less, C: 1% or less, Ni: balance, and the chemical composition of the second alloy material is Cr: 15
-20%, Si: 3-7%, Fe: 35% or less, W: 1
-4%, Sn: 0.5-1.0%, B: 1% or less, C: 1
% Or less, Ni: balance, an apparatus using a cobalt-free alloy material. 2. The apparatus according to claim 1, wherein the device is a valve, one of the components is a valve seat of a valve box of the valve, and the other of the components is a valve seat of a valve body of the valve. An apparatus according to claim 1. 3. An apparatus having at least two alloy components, wherein one of the components is relatively movable with respect to the other, wherein one and the other of the components are Cr: 5 to 5 respectively. 15%, Si: 3 to 7%, Fe: more than 10 to 40%, W: 1 to 4%, B: 1% or less, C: 1% or less, Ni: balance alloy material or Cr: 15 to 20
%, Si: 3 to 7%, Fe: 35% or less, W: 1 to 4
%, Sn: 0.5 to 1.0%, B: 1% or less, C: 1% or less, Ni: An apparatus using a cobalt-free alloy material, characterized by being formed from the remaining alloy material. .