JP5789328B1 - Alloys and equipment for sliding members - Google Patents

Abstract

The present invention provides an alloy for a sliding member and a device having sufficient wear resistance and corrosion resistance even under a high surface pressure and high temperature environment. SOLUTION: 7-17% by mass of chromium, 1-4% by mass of tungsten, 3-7% by mass of silicon, 1% by mass or less of boron, 1% by mass or less of carbon, 3-15% by mass of iron, And the alloy for sliding members which contains 10-20 mass% of copper, respectively, and the remainder is comprised with nickel. In the gate valve 1 having at least one set of valve seat surfaces, one of the valve seat surfaces is formed of the sliding member alloy. [Selection] Figure 1

Description

  The present invention relates to a cobalt-free alloy, that is, an alloy for a sliding member that does not contain cobalt (Co) and a device having the sliding member.

  A set of constituent members that slide relative to the one constituent member is referred to as a pair of sliding members in this specification. Such a sliding member is required to have sufficient wear resistance and corrosion resistance. Therefore, in a device including a sliding member, a sliding member is formed by overlay welding an alloy having excellent wear resistance and corrosion resistance on a main body portion (base material) of the device. For example, the valve seat surface of the valves is a typical sliding member, and the various valves are typical examples of devices provided with the sliding member.

  As a material for forming the sliding member, a Co—Cr—W alloy based on cobalt (Co), chromium (Cr), and tungsten (W) as represented by Stellite (registered trademark) alloy (hereinafter, "Co-based alloy" is widely known.

Numerous valves are used in nuclear power plants, but when a Co-based alloy is used for such valves, the valve seat surface wears or corrodes over time, resulting in cobalt (Co ) Particles in the cooling water. When the cobalt (Co) particles reach the core together with the cooling water, the cobalt (Co) in the cooling water is irradiated with neutrons emitted from the nuclear fuel to cause a nuclear reaction, and the radioisotope cobalt 60 (Co ⁶⁰ ). It becomes. Cobalt 60 (Co ⁶⁰ ) adheres to the inner surfaces (wetted surfaces) of the components of the plant while circulating in the plant together with the cooling water, and increases the radioactivity level of the entire nuclear power plant. This phenomenon is a major cause of worker radiation exposure during periodic inspections. Therefore, there is a strong demand for alternative materials for Co-based alloys. Further, cobalt (Co) is a rare metal valuable as an industrial resource, and it is desired to save its use.

  Therefore, an alloy that does not contain cobalt (Co) is required as a material for the valve seat, and has already been put into practical use. For example, RNiCrB, which is a Ni-based cladding material defined in AWS (American Welding Society) specification (A5.11-54), as represented by COLMONOY® alloy, is carbon (C). 0.4 to 0.8 mass%, silicon (Si) 3 to 5 mass%, chromium (Cr) 10 to 16 mass%, boron (B) 2 to 4 mass%, and iron (Fe). While containing 3 to 5% by mass, the balance is made of nickel (Ni) and does not contain cobalt (Co).

  Since the content ratio of boron (B) is relatively large in RNiCrB, the content ratio of boron (B) in a cobalt-free nickel (Ni) -based alloy is considered as being easily cracked during overlay welding. It has also been proposed to reduce. For example, the alloy described in Patent Document 1 has boron (B) of 0.05 to 1.5 mass%, silicon (Si) of 3 to 7 mass%, chromium (Cr) of 10 to 15 mass%, carbon ( C) is contained in an amount of 0.05 to 1.5% by mass, and the balance is made of nickel (Ni).

  Although the alloy described in Patent Document 1 has reduced cracking during welding, one of the applicants of the present application suppose that one of the sliding members is made of chromium (Cr) in an amount of 5-15. 3% by mass, silicon (Si) 3-7% by mass, iron (Fe) 10-40% by mass, tungsten (W) 1-4% by mass, boron (B) 1% by mass or less, and carbon (C ) 1% by mass or less, and the remainder is made of a first alloy material made of nickel (Ni), the other being 15-20% by mass of chromium (Cr) and 3-7% by mass of silicon (Si). %, Iron (Fe) 35 mass% or less, tungsten (W) 1-4 mass%, tin (Sn) 0.5-1.0 mass%, boron (B) 1 mass% or less, carbon ( C) is contained in an amount of 1% by mass or less, and the remainder is made of nickel (Ni). The invention of a device formed of gold material, a patent has been granted (Patent Document 2).

  Moreover, the said applicant replaced with the said 1st alloy material, 6.5-20 mass% of chromium (Cr), 1-4 mass% of tungsten (W), and 2-7 mass% of silicon (Si). 1% by mass or less of boron (B), 1% by mass or less of carbon (C), and 40 to 50% by mass of iron (Fe), respectively, and the rest is made of an alloy material made of nickel (Ni). A patent has been received for an invention of a device formed with one of the moving members (Patent Document 3). The alloy material according to Patent Document 3 has an advantage that the other material of the sliding member is not limited to the second alloy material. That is, even when the alloy material is combined with other than the second alloy material, excellent wear resistance and corrosion resistance are exhibited.

JP 55-31127 A Japanese Patent No. 2840191 Japanese Patent No. 2955506

  In general, since the valve seat surface of a large-diameter valve is subjected to a high surface pressure, the valve seat surface is heavily worn. In addition, when the temperature increases, the wear of the valve seat surface becomes severe. Certainly, the cobalt-free alloys (first alloy material, sliding member alloy material) disclosed in Patent Documents 2 and 3 have excellent wear resistance and corrosion resistance, but have a large diameter valve exceeding 600 mm. However, when it was used for the valve seat surface of a valve through which high-temperature cooling water exceeding 300 ° C. was passed, the wear resistance and corrosion resistance could not be satisfied. In other words, conventional cobalt-free alloys were inferior to Co-based alloys. Therefore, if the cobalt-free alloy is used as a material for the valve seat surface and the valve is repeatedly opened and closed under a high surface pressure and high temperature environment, the roughness of the valve seat surface increases and the sealing performance is impaired. there were.

  The present invention has been made in view of such circumstances, and an alloy for a sliding member that exhibits sufficient wear resistance and corrosion resistance even under a high surface pressure and high temperature environment, and an apparatus having the sliding member Then, it aims at providing a durable and reliable apparatus.

  In order to solve the above problems, the alloy for a sliding member according to the present invention is composed of 7 to 17% by mass of chromium, 1 to 4% by mass of tungsten, 3 to 7% by mass of silicon, and 1% by mass or less of boron. While containing 1 mass% or less of carbon, 3-15 mass% of iron, and 10-20 mass% of copper, the remainder is made of nickel.

  The apparatus according to the present invention is an apparatus having at least one set of sliding members, wherein one of the sliding members is formed of the alloy for sliding members.

  The other of the sliding members is 15-20% by mass of chromium, 1-4% by mass of tungsten, 3-7% by mass of silicon, 1% by mass or less of boron, 1% by mass or less of carbon, and 35% by mass of iron. %, And 0.5 to 1.0% by mass of tin, respectively, and the balance may be formed of an alloy for a sliding member made of nickel.

  One of the sliding members may be a valve seat surface, and the other of the sliding members may be a counterpart valve seat surface that slides relative to the valve seat surface.

  7-17% by mass of chromium, 1-4% by mass of tungsten, 3-7% by mass of silicon, 1% by mass or less of boron, 1% by mass or less of carbon, 3-15% by mass of iron, and 10% of copper The alloy for a sliding member containing ˜20% by mass, each of which is composed of nickel, is excellent in wear resistance and corrosion resistance.

  In an apparatus having at least one pair of sliding members, if one of the sliding members is formed of the aforementioned alloy, the wear resistance and corrosion resistance are excellent, and excellent sealing performance is exhibited on the sliding surface of the sliding member. To do.

  The other of the sliding members is 15-20% by mass of chromium, 1-4% by mass of tungsten, 3-7% by mass of silicon, 1% by mass or less of boron, 1% by mass or less of carbon, and 35% by mass of iron. %, And 0.5 to 1.0% by mass of tin, respectively, and if the balance is formed of an alloy for a sliding member made of nickel, the sealing performance on the sliding surface of the sliding member Is further improved.

  If the valve seat surface is formed of the aforementioned alloy, a valve having excellent wear resistance and corrosion resistance and having excellent sealing performance can be realized.

It is sectional drawing of the gate valve which illustrates embodiment of this invention, Comprising: (A) is sectional drawing cut | disconnected by the plane parallel to a flow path, (B) is cut | disconnected by the XX 'line | wire of (A). FIG. It is the elements on larger scale around the valve body of a gate valve.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The gate valve 1 shown in FIG. 1 is an illustration of a specific embodiment of the present invention. That is, the gate valve 1 is a device having a set of sliding members, and the sliding members are made of an alloy as will be described later. Hereinafter, the composition of the gate valve 1 and the component composition of the alloy forming the sliding member will be described.

  As is clear from FIG. 1, the gate valve 1 includes a valve box 2 and a valve body 3. The valve box 2 is a housing formed in a hollow cylindrical shape as a whole, and a flow path 4 is formed therein, and fluid flows from the A end to the B end of the flow path 4 when the valve is opened. . The valve body 3 is a partition plate that is disposed in the valve box 2 and opens and closes the flow path 4. In the fully closed state (the state shown in FIG. 1), a valve seat 5 is disposed at a portion of the valve box 2 that contacts the valve body 3. Further, a valve stem 6 is provided above the valve body 3, and the valve stem 6 is connected to the valve body 3. In addition, there is an electric lifting device (not shown) above the valve stem 6 and connected to the valve stem 6. Since it is comprised in this way, the valve body 3 is driven by the said electric raising / lowering apparatus, and moves the inside of the valve box 2 up and down. This figure shows a state in which the valve body 3 is lowered to the lowest position and the flow path 4 is completely closed, that is, a fully closed state. When the electric lifting device is operated to move the valve body 3 upward, the flow path 4 is opened (valve open).

  FIG. 2 is an enlarged view showing details of a joint portion between the valve seat 5 and the valve body 3. The surfaces of the valve seat 5 and the valve body 3 that are in close contact with each other when the valve is closed are generally called valve seat surfaces. Here, the valve seat surface of the valve seat 5 is called the valve seat surface 7 and the valve seat surface of the valve body 3 is called the valve seat surface. It will be called the valve seat surface 8. As shown in FIG. 2, when fully closed, the valve seat surface 7 and the valve seat surface 8 are in close contact with each other to close the flow path 4 (see FIG. 1) in a fluid-tight manner. Further, in the process of shifting from this state to the valve open state, or in the process of shifting from the valve open state to the valve closed state, the valve seat surface 7 and the valve seat surface 8 slide relative to each other. Therefore, the valve seat surface 7 and the valve seat surface 8 correspond to a set of sliding members in the gate valve 1. An intermediate region between the upper and lower valve seat surfaces 8 of the valve body 3 is recessed with respect to the valve seat surface 8, and the region slides with respect to the valve seat surface 7 in the process of moving the valve body 3 up and down. It doesn't move. The pressure of the fluid flowing in the flow path 4 is applied to the valve body 3, and the pressure is transmitted to the valve seat surface 7 via the valve seat surface 8. That is, the valve seat surface 7 and the valve seat surface 8 are configured to press each other by the action of the pressure.

  As described above, the sliding member is required to have high wear resistance and corrosion resistance. Further, if the wear resistance and the corrosion resistance are insufficient, the surfaces of the valve seat surface 7 and the valve seat surface 8 are roughened as the opening / closing operation is repeated, and as a result, the sealing performance is impaired (leakage occurs). . Therefore, the material of the valve seat surface 7 is 7 to 17% by mass of chromium (Cr), 1 to 4% by mass of tungsten (W), 3 to 7% by mass of silicon (Si), and 1 mass of boron (B). % (%) Or less, carbon (C) 1 mass% or less, iron (Fe) 3-15 mass%, and copper (Cu) 10-20 mass%, respectively, with the remainder being nickel (Ni). Alloy (hereinafter referred to as “alloy A”) was selected. Moreover, 15-20 mass% of chromium (Cr), 1-4 mass% of tungsten (W), 3-7 mass% of silicon (Si), and 1 mass of boron (B) as materials for the valve seat surface 8 % Or less, carbon (C) 1 mass% or less, iron (Fe) 35 mass% or less, and tin (Sn) 0.5 to 1.0 mass%, respectively, with the balance being nickel (Ni) (Hereinafter referred to as “alloy B”).

  The above-mentioned alloys A and B are melted by using a well-known high-frequency vacuum melting furnace, then pulverized by water or gas atomization method, and overlay welding is performed on the valve seat 5 or the valve body 3 by powder plasma (PTA) welding. Thus, the valve seat surface 7 and the valve seat surface 8 are formed. The particle size of the powders of alloy A and alloy B is preferably in the range of +70 to +210 mesh. Further, parts other than the valve seat surface 7 and the valve seat surface 8 of the valve seat 5 and the valve body 3, that is, the main body (base material) of the valve seat 5 and the valve body 3 are made of carbon steel.

  Here, the reason for selecting the above component composition for the alloys A and B will be briefly described.

  Chromium (Cr) has been conventionally used conventionally as a component for improving the corrosion resistance. For example, according to the American Society for Testing and Materials (ASTM), Type D-3 Ni-resist is nickel (Ni) 28-32 mass%, silicon (Si) 1.5-3 mass%, and chromium (Cr). In an steam of 133 to 221 ° C. in a nuclear power plant, but is made of Fe (Fe), the balance being substantially composed of iron (Fe). The amount of corrosion is 025 mm / year or less, and the corrosion resistance is almost equivalent to SUS304 or SUS403. By analogy with this fact, it is considered that if chromium (Cr) is contained in the alloy in an amount of 5% by mass or more, sufficient corrosion resistance is exhibited as a valve seat material for a nuclear power plant. Chromium (Cr) is known to increase the hardness and toughness of the alloy. However, if it is excessively contained, the toughness decreases. Therefore, in the alloy A, the content range of chromium (Cr) is 7 to 17% by mass. In the alloy B, the hardness is increased by setting the content range of chromium (Cr) to 15 to 20% by mass.

  Silicon (Si) is necessary to maintain hardness and wear resistance, but if contained excessively, toughness is reduced and welding workability is deteriorated. Was 3-7 mass%.

  Iron (Fe) is a component that lowers the hardness of the overlay and improves weldability. In addition, the iron (Fe) wear powder is easily oxidized and suppresses the occurrence of seizure and galling. However, if it is excessively contained, the corrosion resistance of the alloy is lowered. Therefore, in the alloy A, the content range is 3 to 15% by mass. In the alloy B, the content range was set to 35% by mass or less.

  Tungsten (W) maintains hardness by increasing the hardness and generates tungsten oxide having lubricity during sliding to prevent seizure and galling. Therefore, tungsten (W) is contained in alloy A and alloy B. The range of the amount was 1 to 4% by mass.

  Copper (Cu) prevents seizure and galling and improves sliding characteristics. However, if it is excessively contained, wear resistance and toughness are lowered. Therefore, in alloy A, 10 to 20% by mass was contained.

  Tin (Sn) forms a lubricious thin film to prevent seizure and galling. However, if contained excessively, toughness is reduced and welding workability is deteriorated. Mass% was contained. It was not contained in Alloy A. If tin (Sn) is contained in one of the sliding member groups, a lubricious thin film is formed between them.

  Boron (B) and carbon (C) are impurities, and if contained excessively, cracks occur during welding and heat treatment, so the contents of Alloy A and Alloy B are limited to 1% by mass or less. Note that boron (B) and carbon (C) have an effect of increasing the hardness of the alloy, and may be positively contained. However, because of the above-described cracking problem, in the alloy according to the present invention, The content is limited as described above.

  In order to confirm the effect of the present invention, there are three types of gate valves 1 in which the diameter of the flow path 4 is 600 mm and the component compositions of the materials of the valve seat surface 7 and the valve seat surface 8 are different (Examples) 1 and 2 and a comparative example). Table 1 shows the composition of the components of the valve seat surface 7 and the valve seat surface 8 for Examples 1 and 2 and the comparative example.

  The component compositions of Alloys A1 and A2 shown in Table 1 are included in the range of the component composition of Alloy A, and Alloy B1 is included in the range of the component composition of Alloy B. That is, alloys A1 and A2 are a kind of alloy A, and alloy B1 is a kind of alloy B. In addition, the component composition of the alloy C is included in the range of the component composition of the first alloy described in Patent Document 2.

  In the gate valve 1 according to Example 1, Example 2, and Comparative Example, the channel 4 was opened and closed 50 times in a state where steam at 302 ° C. and 8.74 MPa was flowed. That is, the valve body 3 was slid 50 times with respect to the valve seat 5. Thereafter, the surface roughness of the valve seat surfaces 7 and 8 is measured, the gate valve 1 is fully closed, and the A end of the flow path 4 is filled with water at room temperature, so that the valve body 3 is 8.74 MPa. Table 2 shows the results of measuring the amount of water leakage by applying a water pressure of. The surface roughness of the valve seat surfaces 7 and 8 before the test was in the range of 0.09 to 0.26 μm Ra (that is, when the gate valve 1 was manufactured, the surface roughness of the valve seat surfaces 7 and 8 was Finished to fit within range).

  Generally, a valve having a size and application such as the gate valve 1 is evaluated as good if the depth of the sliding trace is 1 μmRa or less. This is because if it is 1 μmRa or less, the valve seat surface can be easily restored by the sliding operation in the valve maintenance operation. According to Table 2, the surface roughness of the valve seat surface 7 in the comparative example reaches 2.40 μmRa and greatly exceeds 1 μmRa. As a result, leakage of 25 ml / min occurs. That is, in the comparative example, there is a problem that the sealing performance is impaired by opening and closing about 50 times.

  On the other hand, in Example 1, the surface roughness of the valve seat surface 7 reaches 1.28 μmRa, which is considered to be slightly rough, but the leakage amount is ¼ or less (6 ml / min) of the comparative example. Moreover, in Example 2, the surface roughness of the valve seat surface 7 remains at 0.88 μmRa, and the amount of leakage is not detected. Thus, according to this invention, it is excellent in abrasion resistance and a favorable sealing performance is maintained even if it repeats opening and closing.

  As mentioned above, according to Table 2, the gate valve 1 which concerns on this invention (Example 1, 2) is excellent in abrasion resistance and corrosion resistance compared with the gate valve 1 which concerns on a prior art (comparative example). Thus, it can be understood that sufficient sealing performance is maintained even when the opening / closing operation is repeated. According to the present invention, it can be understood that an alloy excellent in wear resistance and corrosion resistance can be obtained as compared with a conventional alloy. Further, if the valve seat is formed of the alloy according to the present invention, it can be understood that sufficient sealing performance is maintained because the surface of the valve seat does not become rough even when the valve is repeatedly opened and closed. In other words, according to the present invention, it can be understood that a device having a sliding member having high durability and reliability, for example, valves is provided.

  In addition, said embodiment shows an example of the specific embodiment of this invention, Comprising: The technical scope of this invention is not demarcated. The present invention can be freely modified, applied or improved within the scope of the technical idea described in the claims.

  In the above description of the embodiment, the gate valve 1 is illustrated as a specific example of the device according to the present invention, but the device to which the present invention is applied is not limited to the gate valve 1. The device according to the present invention may be any device as long as it has at least one pair of sliding members. Needless to say, the device according to the present invention is not limited to a device driven by an electric motor. For example, it may be a device operated manually (manually) or a device driven by oil pressure.

  In the above embodiment, the sliding member (valve seat surfaces 8 and 6) is exemplified by powder plasma (PTA) welding, but means for forming the sliding member is used for PTA welding. It is not limited. Overlay welding may be performed by other welding methods, or a sliding member formed separately from the base material may be joined to the base material. Alternatively, the sliding member may be formed separately from the base material and fastened and fixed to the base material by appropriate fastening means. Needless to say, the base material is not limited to carbon steel. The base material may be, for example, low alloy steel or stainless steel, other metal material, or non-metal material.

  Further, the use of the alloy according to claim 1 is not limited to the device according to claims 2 to 4. It is useful as a material for various machinery.

  Moreover, in the said embodiment, the example which forms the valve seat surface 7 with the alloy (alloy A) of Claim 1, and forms the valve seat surface 8 with the alloy (alloy B) of Claim 3 is shown. However, the arrangement of the alloy A and the alloy B may be reversed. That is, the valve seat surface 7 may be formed of (alloy B) and the valve seat surface 8 may be formed of (alloy A). The alloy combined with the alloy according to claim 1 (alloy A) is not limited to the alloy according to claim 3 (alloy B). An alloy having other composition may be used.

  In the description of the embodiment and the claims, it is described that “the balance is made of nickel”, which means that substantially all the balance is made of nickel (Ni). It does not mean that components other than (Ni) are not included at all in a strict sense. In other words, the presence of a trace amount of impurities that are technically difficult to remove, or a trace amount of impurities that does not have a metallurgical effect is allowed.

DESCRIPTION OF SYMBOLS 1 Gate valve 2 Valve box 3 Valve body 4 Flow path 5 Valve seat 6 Valve stick 7 Valve seat surface 8 Valve seat surface

Claims (4)

  7-17% by mass of chromium, 1-4% by mass of tungsten, 3-7% by mass of silicon, 1% by mass or less of boron, 1% by mass or less of carbon, 3-15% by mass of iron, and 10% of copper An alloy for a sliding member containing ˜20% by mass, each of which is made of nickel. In an apparatus having at least one set of sliding members,
One side of this sliding member is formed with the alloy for sliding members of Claim 1. The apparatus characterized by the above-mentioned. The other of the sliding members is 15-20% by mass of chromium, 1-4% by mass of tungsten, 3-7% by mass of silicon, 1% by mass or less of boron, 1% by mass or less of carbon, and 35% by mass of iron. % Or less and 0.5 to 1.0% by mass of tin, respectively, and the balance is formed of an alloy for a sliding member made of nickel. machine. The one of the sliding members is a valve seat surface, and the other of the sliding members is a counterpart valve seat surface that slides relative to the valve seat surface. Item 4. The device according to Item 3.

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