JPH07305129A - Device using cobalt-free alloy material - Google Patents

Abstract

PURPOSE:To develop valve device excellent in wear resistance and corrosion resistance and free from the generation of seizing and cracking by producing the valve sear parts of a valve box and a valve body sliding with each other in a valve device from Ni base alloys of specified compsns. contg. no Co. CONSTITUTION:In this valve device 10 constituted of a valve box 11 having a flow passage 11a as a passage for fluid and a valve body 12 with a wedge shape moving in the upper and lower directions 15 for shutting off or opening the passage 11a, valve seats 14 and 13 as the sliding parts of a valve box 11 and a valve 12 are respectively produced from Ni base alloys having the following compsns.: by wt., 5 to 15% Cr, 3 to 7% Si, 10 to 40% Fe, 1 to 4% W, <1% B, <1% C, and the balance Ni, and the valve seat 14 is constituted of an Ni alloy having a compsn, contg. 15 to 20% Cr, 3 to 7% Si, <35% Fe, 1 to 4% W, <1% B, <1% C, 0.5 to 1.0% Sn, and the balance Ni. Since both do not contain Co, the inexpensive valve device free from radioactive fault caused by Co as the cooling material of a nuclear power plant can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cobalt-free or cobalt (Co) -free alloy materials, and more particularly to devices such as valves having relatively movable components such as valve bodies and valve bodies. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a Co-based material has been used as a valve seat material in order to impart wear 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 this high-temperature and high-pressure water. Therefore, when a Co-based alloy is used as a valve seat material, Co is eluted from the metal surface into the reactor water by the corrosive action of the high temperature and high pressure water. Further, as the valve body slides with respect to the valve box valve seat portion as the valve opens and closes, a small amount of Co abrasion powder is generated, which is also brought into the reactor water.

Since these Co enter the core and are irradiated with neutrons to be radiated and become isotope Co60, which circulates in the coolant system and adheres to the pipes, valves and other equipment, the entire nuclear power plant. Since the radioactivity level of the above is increased, there is a possibility that the radiation dose of the worker during the periodic inspection may increase. 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 a rare metal that is a valuable industrial resource.

[0004]

As a cobalt-free material which does not use Co, Ni-based and Fe-based materials have hitherto been used.
Although base alloys have been adopted, these alloys have a problem that they are inferior in wear resistance and corrosion resistance as compared with Co base alloys.

For example, R NiC, which is a Ni-based overlay material commonly referred to as Colmonoy, which is defined in the specification (A5.11-54) of AWS (American Welding Society).
In rB, carbon C: 0.4 to 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, since boron B is contained in a relatively large amount of 2 to 4%, when overlay welding is performed on a large product, It has been known that cracks occur in the bed.

Further, an alloy obtained by improving this Colmonoy material so as to reduce the content of boron B is disclosed in JP-A-55-31127. In this alloy, boron B: 0.05-1.5%, silicon Si: 3-7%,
Chromium Cr 10-15%, Carbon C: 0.05-1.5%
The balance was Ni, but the wear resistance was insufficient even though cracks during welding were reduced due to the reduction of boron B.

Therefore, the present invention has been made in order to solve the problems of the above-mentioned conventional techniques, and it is possible to use a cobalt-free alloy material containing no Co as a build-up material, and to improve wear resistance. Its main purpose is to provide a device excellent in both corrosion resistance and corrosion resistance.

[0008]

In order to achieve the above object, the present invention according to claim 1 has at least two alloy components, one of which is relative to the other. In a device that is movable, the constituent members are made of a Ni-Cr-Si-Fe-W-based cobalt-free Ni-based alloy having different hardnesses and a second alloy material.
While being formed from an alloy material, the chemical composition of the first alloy material is Cr: 5 to 15%, Si: 3 to 7%, Fe: 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 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 having a valve body that slides under the action of hydraulic pressure, such as a sluice valve, is suitable.

According to another aspect of the present invention, in a device in which one of the constituent members is relatively movable with respect to the other, one of the constituent members and the other of the constituent members are made of Cr: 5 to 5 respectively.
15%, Si: 3 to 7%, Fe: 10 to 40%, W: 1
~ 4%, B: 1% or less, C: 1% or less, Ni: the 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: The balance is provided, and an apparatus using a cobalt-free alloy material is provided.

[0010]

[Function] The chemical composition of the cobalt-free alloy material is Cr:
5-15%, Si: 3-7%, Fe: 10-40%,
When W: 1 to 4%, B: 1% or less, C: 1% or less, and Ni: balance, an alloy material excellent in both wear resistance and corrosion resistance can be obtained. Also, this is Cr: 15 to 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 high pressure such as a nuclear power plant, it has good wear resistance and corrosion resistance.
A highly reliable device can be obtained.

[0012]

Preferred embodiments of the present invention will now 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 motor-driven valve device having a valve seat in which the present invention is embodied, that is, a main part of a sluice valve, is generally indicated by reference numeral 10. In the figure, a sluice valve (valve device) 10 includes a hollow valve box 11 that defines a flow passage 11a of a fluid flowing at the time of opening the valve as shown by an arrow 17 as well known, and the flow passage 11a. As shown in the drawing, a wedge-shaped valve body 12 is provided between a valve closing position for shutting off and a valve opening position (not shown) for opening a part or all of the valve body, which is movable up and down in the direction of the arrow 15 ing. Disc 1
The lower end of the valve rod 12a is connected to 2 in a known manner, and the valve body 12 can be moved as described above by operating the valve rod 12a.

The sliding surface between the valve box 11 and the valve body 12 is generally called a valve seat, and in FIG.
The annular valve seat (constituent member) that is the sliding surface of
Further, the annular valve seat portion (constituent member) which is the sliding surface of the valve body 12 is indicated by reference numeral 13. Disc 12
When the valve is fully closed, the fluid pressure acts on its side surface as indicated by arrow 16, so if the valve body 12 is opened and closed in the arrow direction 15 against this pressure, each valve seat portion 1
3 and 14 are worn.

FIG. 2 shows the details of the valve seat portions 13 and 14 described above. According to the present invention, as the material of the valve body valve seat portion 13 and the valve box valve seat portion 14, both of Cr-Si-Fe are used.
Although -W-based Ni-based alloys are 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 one of Cr: 5 to 15% and Si: 3
~ 7%, Fe: 10-40%, W: 1-4%, B: 1%
Hereinafter, it is formed from an alloy material (1) containing C: 1% or less, and the other is Cr: 15 to 20%, Si: 3 to 7%, Fe: 35.
% Or less, W: 1 to 4%, Sn: 0.5 to 1.0%, B: 1
%, C: 1% or less, it is preferable to form the alloy material (2). Either the valve body valve seat portion 13 or the valve box valve seat portion 14 may be formed of the alloy material (1).

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

In order to build up the sample alloys shown in Table 1 as the valve seat portions 13 and 14, the alloys are melted in a well-known high-frequency vacuum melting furnace and then finely pulverized by a water or gas atomizing method. 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.

This powder is used in a well-known plasma powder overlay welding method to form S25C and SCPH2 which are types of carbon steel.
Disc (when the valve diameter is 145 mm) and the actual valve body and valve seat, that is, the actually used valve body and valve seat (bore diameter:
(For 650 mm), a two-layer overlay welding was performed on the above, and then a wear test body, a valve body and a valve seat were processed and rubbed with a 600 mesh paper file before the test. The sliding wear test was performed after considering the leakage of water under the following differential pressure load conditions.

The wear test was carried out for a test piece having a diameter of 145 mm in room temperature water and 300 ° C. saturated water by using a mechanism simulating the sliding state of a sluice valve.
It was carried out under the condition that a differential pressure of 88 Kgf / cm ² was applied.
Note that the valve seat surface pressure when this differential pressure is applied is calculated as 2
It becomes 0 Kgf / mm ² .

Regarding the actual valve body and the 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 between room temperature and 300 ° C.).
valve used at f / cm ² or less), load a differential pressure of 87.9 Kgf / cm ² in room temperature water, and slide at a sliding speed of 15
The test was performed at 0 mm / min. The valve seat surface pressure under the condition that 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 sliding times is 100 times 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 body was measured by a well-known method, and a valve seat surface having a sliding trace depth of 1 μm RA or less was evaluated as good. The roughness of 1 μm RA is a roughness that allows the valve seat surface to be easily restored by the rubbing work in the maintenance work of the valve. As can be seen from Table 1, in the test body, the valve body and the valve seat to which the present invention is applied,
The surface roughness after sliding 100 times 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, if the hardness difference is 3 or less in HRC, when applied to the sliding part, leakage occurs at the initial stage of sliding and after sliding, The roughness was 1 μm RA or more and the slidability was poor. 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 impart such hardness difference.

As is clear 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
-40%, W: 1-4%, B: 1% or less, C: 1% or less of the alloy material (1), the other is Cr: 15-15
20%, Si: 3 to 7%, Fe: 35% or less, W: 1 to
4%, Sn: 0.5-1.0%, B: 1% or less, C: 1%
It is formed from the following alloy material (2). In addition, the hardness difference between both alloy materials is 5 or more (Vickers hardness Hv) in Rockwell HRC from the viewpoint of preventing seizure and galling.
70 or more).

Here, the basis for selecting the ratio of each chemical composition will be described. Cr is generally used conventionally to improve the corrosion resistance. However, since the alloy materials (1) and (2) used according to the present invention are Ni-based, they are essentially excellent in corrosion resistance, and Cr does not require much. For example, Type D-3 niresist by American Society for Testing and Materials (ASTM) is Ni: 28 to 32.
%, Si: 1.5 to 3%, Cr: 2.5 to 3%, and the balance is substantially an Fe-based alloy, but 0 in steam of 133 to 221 ° C. in a nuclear power plant. .0
Shows corrosion amount of 25 mm / year or less, SUS304, S
Since it shows almost the same corrosion resistance as US403, if the overlay material of the present invention contains 5% or more, it exhibits sufficient corrosion resistance as a valve seat material for a nuclear power plant. But,
Since Cr is an element that improves the oxidation resistance of the metal, it prevents oxidation of wear powder generated by sliding of the valve seat, so C
If r is added in an amount of 20% or more, a metallic peeling piece is generated, which may cause seizure or galling on the sliding portion. Therefore, the range of Cr is preferably 5 to 20%.

Next, with respect to silicon Si, it is necessary to maintain hardness and wear resistance, but if added in a large amount, toughness decreases and welding workability deteriorates, so 3-7.
You can put it as%.

Fe reduces the hardness of the overlay material and improves the weldability. Further, abrasion powder that is easily oxidized during sliding is less likely to cause seizure or galling, but if added in a large amount, the corrosion resistance of the alloy is deteriorated. Therefore, 10 to 40% of Fe is added to the soft side alloy, and the Fe content of the hard side alloy is limited to 35% or less. As a result, the difference in Rockwell hardness HRC becomes 5 or more. When plasma powder overlay welding of the first and second alloy materials is performed on 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 the Fe of the second alloy material is 40% and the Fe of the first alloy material is 35% or less, the required hardness difference can be obtained.

Further, since tungsten W has a high hardness to maintain wear resistance and produces a tungsten oxide having lubricity during sliding to prevent seizure and galling, 1 to 4% is required. 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 decreases and the weldability deteriorates. Therefore, 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 contained in large amounts, they deteriorate the welding workability. Therefore, they are limited to 1% or less to prevent cracking during welding and heat treatment. Both B and C have the effect of increasing the hardness of the overlay material, but in order to maintain wear resistance, S
Since it is desirable to increase the hardness by i, the content as an impurity is limited as described above in the present invention.

The case where the present invention is applied to the valve seat portion of the sluice valve has been described above. However, the present invention is not limited to this embodiment, and a spherical valve or a valve with less sliding of the valve seat can be used. The same can be applied to a check valve or the like in which the seat does not slide. In addition to the valve device, the present invention can be suitably used for a sliding part or a guide part of any device that causes sliding (for example, shafts and bearings of various devices), and further under high temperature and high pressure. It can likewise be applied to any suitable component that requires high wear and corrosion resistance for use, and this component does not necessarily have to be a sliding member.

For example, FIG. 3 shows a sectional view of the valve device 10 of FIG. 1 taken along a plane perpendicular to the plane of the drawing, in which sliding of both on the valve body side and the valve box side is performed. 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 from an alloy material having the above-described composition.

Further, when the Ni-based alloy according to the present invention is built up on the valve seat, the sliding part or the guide part as described above, it is not the plasma powder build-up welding described above but powder spraying,
They may be joined or manufactured by TIG welding or gas welding using a welding rod, or powder metallurgy, or may be cast.

[0032]

As described above, according to the present invention, since high wear resistance and corrosion resistance can be obtained, seizure, galling and cracking do not occur, and it is suitable for use even under high temperature and high pressure. It is possible to provide a highly reliable device.

[Table 1]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing a sluice valve having a valve seat portion according to the present invention.

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

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

FIG. 4 is a graph showing the relationship between the 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 portion (constituent member), 14 ... Valve box valve seat portion (constituent member), 18 ... Valve body side guide Part (component),
19 ... Guide portion (constituent member) on the valve box side.

Claims (3)

[Claims] 1. An apparatus having at least two alloy components, one of which is movable relative to the other, each of which is Ni-Cr-S.
The i-Fe-W-based cobalt-free Ni-based alloy is formed from a first alloy material and a second alloy material having different hardness, and the first alloy material has a chemical composition of Cr: 5.
-15%, Si: 3-7%, Fe: 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 to 2
0%, 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: balance, a device using a cobalt-free alloy material. 2. The apparatus is a valve, one of the constituent members is a valve seat portion of a valve box of the valve, and the other of the constituent members is a valve seat portion of a valve body of the valve. The device according to. 3. An apparatus having at least two alloy constituent members, wherein one of the constituent members is relatively movable with respect to the other, and one and the other of the constituent members are each made of Cr: 5 to 5. 15%, Si: 3 to 7%, Fe: 10
40%, W: 1 to 4%, B: 1% or less, C: 1% or less,
Ni: Alloy material as the balance or Cr: 15 to 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: A device using a cobalt-free alloy material, characterized by being formed from the balance alloy material.