JPS62167980A - Valve - Google Patents

Abstract

PURPOSE:To enhance the resistance to erosion and seizure, by making one valve contact surface of a cobalt-based Co-Cr-W alloy, and another valve contact surface of a nickel-based alloy of 400 or more in hardness (Hv). CONSTITUTION:The contact surface of one of a valve casing and a valve element is made of a cobalt-based Co-Cr-W alloy, while that of the other is made of a nickel-based alloy or an iron-based eduction-hardened alloy, which has a hardness (Hv) of 400 or more. For example, Stellite 3, 6, 21 or 25 is used as the cobalt-based Co-Cr-W alloy. For example, an Ni-Cr-Mo-Nb alloy, an Ni-Cr-Al-Mo alloy or an Ni-Cr-B-Si-C-Fe alloy is used as the nickel-based alloy of 400 or more in hardness (Hv).

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a valve with excellent seizure resistance and erosion resistance.

[Technical background of the invention and its problems]

Conventionally, the valve bodies and valve seats of valves used in various plant fields such as chemical and atomic couplants have been coated with C to give them anti-lotion properties and anti-seizure properties.

A base Co-Cr-W alloy (commonly known as stellite) is welded.

However, recently, from the viewpoint of the depletion of Co resources and the safety improvement of reaction control 1M sub-couplets in chemical plants, Ni or Fe-based substrates have been introduced in place of the above-mentioned stellite in order to eliminate the release of Co. Research is being carried out on valves that use heavy-duty lotions and wear-resistant alloys for the valve seat of the valve body and/or the valve seat of the valve body.

However, the conventionally known Ni- or Fe-based alloys do not have sufficient properties in terms of corrosion resistance and seizure resistance compared to Co-based stellite.

[Purpose of the invention]

The present invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a valve body that releases less cobalt particles or cobalt ions in various plants and has excellent resistance to heavy lotion and seizure resistance. The purpose is to

[Summary of the invention]

As a result of studying methods to improve heavy lotion resistance and seizure resistance, the inventors found that if the valve seat surfaces that come into contact with each other during sliding are made of similar and sticky materials, the amount of wear will be large.
It was found that burn-in easily occurs. Therefore, the present invention was created based on the idea that equivalent characteristics could be obtained without using stellite by using specific different materials in pairs.

That is, the present invention is characterized in that one valve seat surface of the valve body or valve body is made of a Co-Cr-W based cobalt-based alloy, and the other valve seat surface is made of a nickel-based alloy or an iron-based precipitation hardening alloy. By combining different materials, it is possible to obtain a valve with excellent seizure resistance.

Specific examples of Co-0r-W type cobalt-based alloys used in the present invention include 1, stellite, 3. 6, 21. 25 can be mentioned.

-Cr -AQ -Mo system, Ni-Cr -B -5i
-C-Fe type etc. are mentioned.

These alloys are used as overlay alloys with excellent corrosion resistance and heavy lotion resistance. Ni with Hv 400 or more
By combining the base alloy and the above cobalt-based alloy,
Good seizure resistance.

In particular, it is preferable to use a valve seat alloy consisting of 15 to 45% chromium, 3 to 15% niobium, and 220% or less molybutton, the balance being nickel.

First, chromium is a necessary component for improving corrosion resistance as well as oxidation resistance and hardness at high temperatures, and its composition ratio is less than 15%, preferably 20 to 35%. Niobium combines with chromium and nickel to form intermetallic compounds such as Cr and Nb to increase hardness, and is a necessary component for wear resistance and heavy lotion resistance.If the composition ratio is less than 3%, the effect is insufficient. If the content exceeds 15%, the toughness will decrease and the mechanical strength will be impaired.Molybdenum is preferably 7 to 15%.Molybdenum improves corrosion resistance and hardness, wear resistance, and heavy lotion resistance due to solid solution strengthening. This range was chosen because if the composition ratio exceeds 20% of the components necessary to improve the hardness, the effect will be saturated and the toughness will decrease. Note that the composition range of molybdenum is preferably 5 to 15%, and in this Ni-based alloy, a part of niobium may be replaced with tantalum, and a part of molybdenum can also be replaced with tungsten. Furthermore, it may contain manganese, silicon, or the like as a deoxidizing and denitrifying agent that is added during melting.

Further addition of 20% or less iron to the above alloy contributes to strengthening the base material and improving toughness. Effective in small amounts, but only 3%
The content is preferably 3 to 12%, because if it exceeds 20%, the strength of the base material will decrease and the mechanical strength of the alloy will be impaired.

In addition, as a Ni-based alloy, carbon 0.3 to 1.5%, chromium As
5-25%, 1111m0.5-6.0%, 0 silicon
．． 5 to 6.0%, 10% or less of iron, and the remainder substantially of nickel may be used.

Carbon is an effective element for increasing wear resistance and hardness, but when it is less than 0.3%, both wear resistance and hardness are low, while when it exceeds 1.5%, toughness decreases. ~1.5%. Preferably 0.4
Silicon and boron are effective elements for increasing wear resistance and strength by forming silicides and borides, respectively, but when the amount is less than 0.5%, the effect is lost. If it is not sufficient or contains a large amount, coarse silicides and borides will be formed and the toughness will decrease.
% or less. In addition, boron is preferably 0.5 to 5.0%,
2.5 to 6.0% silicon is good; iron contributes to strengthening the base and improving thermal shock resistance, but if it exceeds 10%, the strength of the base decreases and mechanical strength is lost. It is. Note that it is preferably 1 to 6%.

Furthermore, chromium is a necessary component for corrosion resistance and strengthening the base of the alloy, but if it is less than 5%, the effect is insufficient.
In addition, if it exceeds 25%, the toughness decreases, so 5 to 25%
%. Note that it is preferably 10 to 20%.

Examples of Fe-Cr-Ni based iron-based precipitation hardening alloys used in the present invention include 5US630 and 5US631.
Examples include maraging steel.

In particular, the weight ratio is 7-14% Cr, 6-10% Ni, Al
10.5-2.0%, Mo1.5-3%, C0.1%
Iron-based precipitation hardening alloys having the following composition with the balance being Fe are suitable for use in the present invention because they have excellent hardness and corrosion resistance.a Cr is essential for improving corrosion resistance and is 7%
The above is necessary. However, a large amount of Ni promotes the formation of ferrite and reduces hardness, so the content is limited to 14% or less. Preferably it is 11.5 to 13.5%. Ni is 6 to cause precipitation hardening phenomenon and suppress the formation of ferrite.
It is necessary to add more than %. However, the inclusion of Nagaka promotes the formation of austenite and lacks strength, so the content is limited to 10% or less. Preferably it is 7.0 to 9.0%. ^2 needs to be added in an amount of at least 0.5% to cause precipitation hardening. However, since a large amount of Ni will reduce processability, the content should be limited to 2% or less. aMo is preferably added in an amount of 0.7 to 1.5%, and must be added in an amount of at least 1.5% to improve corrosion resistance and strength. However, the content is limited to 3% or less because a large amount of content promotes the formation of 9-lite. Preferably it is 1.7 to 2.5%. Carbon is a component that improves strength and suppresses the formation of ferrite, but its content is limited to 0.1% or less, preferably 0.05% or less, since a large amount of carbon impairs corrosion resistance and ductility.

Cobalt-based alloys such as those explained above, Cr-Ni-
Fe-based iron-based precipitation hardening alloys and Ni-based alloys may be welded to the surface of the valve body or valve body, for example, or may be joined by brazing, diffusion bonding, screws, etc., and the sliding surface may be It is sufficient if it is made of an alloy.

[Embodiments of the invention]

The present invention will be explained in detail below.

Table 1 shows the chemical composition of the test gold. For Nα1 to Nα5, test pieces were taken from welding rods having an outer diameter of 4 mm manufactured using a high-frequency induction melting furnace and overlay welded on the surface of 5US316. In addition, for Mo6.7, hot forging was performed after melting using a high frequency vacuum induction melting furnace, and 950 to 1
Solution treatment at 050°C for about 1 to 2 hours and 500 to 6
Test pieces were taken from those subjected to aging treatment at 00°C for about 1 to 3 hours.

The erosion resistance test was conducted using amplitude Dotua,
Testing was carried out under the conditions of a vibration frequency of 6.5 KHz and a test piece duration of 180 minutes, and the amount of wear on the test piece was measured. The results are also listed in Table 1.

As is clear from Table 1, Nα1 to Nα7 according to the present invention have a wear amount of 12 compared to conventional SUS, which is said to have excellent lotion properties.
It was confirmed that it was smaller than 304 (&8) and had excellent lotion properties.

(Leaving space below) Next, using the alloys of samples Ha 1 to 7 and the combinations shown in Table 2, a gate valve with a nominal diameter of 100 m as shown in Figure 1 was manufactured, and the airtightness of the valve after opening and closing operations was tested. In the figure tested, 1 shows the valve box, 2 shows the valve seat of the valve box, 3 shows the valve body, 4 shows the valve seat of the valve body, 5 shows the valve stem, 6 shows the bonnet, and 7 shows the handle. In addition, as a comparative example, using the alloys 1 and 4.6 above, the second
Gate valves of the same structure were manufactured using the combinations shown in the table and tested under the same conditions. The results are also shown in Table 2.

The opening/closing operation was performed 100 times under a surface pressure of 2 kg/m'', and the airtightness test was conducted by passing high-pressure water and measuring leakage on the outlet side.

(The following is a blank space) Table 2 As is clear from Table 2, the gate valve according to the present invention has the same seizure resistance as the one using the cobalt-based alloy of Comparative Example 1, which is conventionally used for the valve seat. It was confirmed that it has excellent wear resistance.

〔Effect of the invention〕

As is clear from the above results, the valve according to the present invention has excellent seizure resistance compared to the Co-based alloy used for the valve body and the valve seat of the valve body. In addition, by being able to reduce the release of Co,
This valve is suitable for opening and closing flow paths in various plants such as chemical and especially nuclear power plants.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a gate valve showing an embodiment of the present invention. 1...Valve box 2...Valve seat of the valve box 3...
Valve body 4... Valve seat of the valve body 5... Valve stem
6...Bonnet 7...Handle agent Patent attorney Nori Chika Ken Yudo Kikuo Takehana Figure 1

Claims (6)

[Claims] (1) One valve seat surface of the valve body or valve body is made of Co-Cr.
- A valve characterized in that it is made of a W-based cobalt-based alloy, and the other valve seat surface is made of a nickel-based alloy having a hardness (Hv) of 400 or more. (2) The nickel-based alloy has a weight ratio of 15 to 45% Cr.
, Nb 3 to 15%, Mo 20% or less, and the balance Ni. (3) The nickel-based alloy has a weight ratio of 15 to 45% Cr.
, Nb 3 to 15%, Mo 20% or less, Fe 20% or less, and the balance Ni. (4) The nickel-based alloy has a weight ratio of C0.3 to 1.5.
%, Cr5-25%, Si0.5-6.0%, B0.5
The valve according to claim 1, having a composition of 6.0% to 6.0%, 10% or less of Fe, and the balance Ni. (5) One valve seat surface of the valve body or valve body is made of Co-Cr.
- Made of W-based cobalt-based alloy, the other valve seat surface is F
A valve characterized by being made of an e-Cr-Ni iron-based precipitation hardening alloy. (6) The iron-based precipitation hardening alloy has a weight ratio of Cr7 to 14.
%, Ni6-10%, Al0.5-2.0%, Mo1.
The valve according to claim 5, characterized in that the valve has a composition of 5 to 3%, C 0.1% or less, and the balance Fe.