JPH03100139A - One-end sealed metallic tube and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the generation of cracks in the metallic tube caused by the difference in thermal expansion, in a one-end sealed metallic tube in which one end part is made of a tube the other end part is sealed, by integrally forming the sealed part and the tube part with metals of the same kind. CONSTITUTION:In a one-end sealed tube provided with end parts 1 and 2 in one direction and the other direction, having a tube part 3 between them and the end part in one direction is regulated as a sealed part 4, the end part 2 in one direction and the tube part 3 are constructed from the same high m.p. metals contg. W, W alloy, Mo and Mo alloy, and which is formed from the constitution in which the end sealed part 1 is not subjected to joining such as welding and brazing. In this way, since the sealed part and the tube part are integrally formed with metals of the same kind, cracks caused by the difference in thermal expansion are not generated, and since the tube is not subjected to unnecessary high temp. treatment such as welding and brazing, ductile-brittle transition temp. is reduced and the mechanical characteristics such as tensile strength and elongation can be made better.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used for cooling pipes for high-temperature vacuum furnaces and atmospheric furnaces, thermocouple protection tubes for the above-mentioned furnaces or melting equipment, gas detection introduction pipes, etc. Regarding heat-resistant single-sealed metal pipes.

[Prior Art] Generally, high-temperature furnaces are filled with a vacuum or a reducing gas such as hydrogen, argon or helium.

It is filled with an inert gas such as xenon, and various materials are heat-treated in this state. For this reason.

Due to the conditions of use, single-sealed pipes such as cooling pipes and thermocouple protection tubes installed in high-temperature furnaces are manufactured from materials with excellent mechanical strength and heat resistance that can withstand vacuum and high pressure. , for example, W.

There are W alloys, Mo, Mo alloys, etc. Single-sealed pipes made of these metal materials have a through-hole pipe made of the same kind of metal as the tube part, and a cap or plug made of the same kind of metal is attached to one end by electron beam welding (abbreviated as EB method), It is manufactured by joining by arc welding, butt welding, or brazing.

[Problems to be Solved by the Invention] However, metals such as W and W alloys are formed by such welding or brazing methods.

Single-sealed pipes made of metal materials such as Mo and Mo alloys are
A temperature higher than unnecessary recrystallization when the base material and the plug are welded or bonded 9 For example, the recrystallization temperature of W is about 1580@, and the recrystallization temperature of Mo is about 1380'K.

The heated parts of the base material and plug become brittle. Also when using at high temperatures.

Brazed parts may melt.

Therefore, this type of single-sealed pipe has extremely low mechanical strength and poor pressure resistance, and cracks may occur at the joint between the base material and the stopper, which may cause gas leakage, reducing reliability in performance. The quality was low and it was a problem.

In view of the above drawbacks, the technical object of the present invention is to provide a highly reliable single-sealed metal pipe that has high mechanical strength at high temperatures and does not cause gas leakage, and a method for manufacturing the same.

[Means for Solving the Problems] According to the present invention, the tube portion has one end and the other end and extends between the one end and the other end. In a single-sealed metal pipe whose end is sealed, the one sealed end and the tube are made of the same high-melting point metal material.

This high melting point metal material is selected from a group including W, W alloy, Mo, and Mo alloy, and has an integral structure in which the end sealing part is not joined by welding, brazing, etc. A single-sealed metal pipe is obtained.

According to the second aspect of the present invention, there is obtained a single-sealed metal pipe characterized in that the two-sealed end portion and the pipe portion of the single-sealed metal pipe are integrated and have the same mechanical properties. It will be done.

Furthermore, according to the present invention, a round bar made of a high melting point metal material selected from the group including W, W alloy, Mo, and Mo alloy, and having one end and the other end, is moved from one end to the other end. A hole is drilled to a length that does not reach the one end, and warm plastic working such as forging, rolling, and rolling is performed at a heating temperature below the recrystallization temperature to give a predetermined shape. There is obtained a method for manufacturing a single-sealed metal pipe, characterized in that the single-sealed metal pipe is integrally formed with the pipe portion connected to the pipe without welding or brazing.

[Effect] The pipe according to the present invention is made of commercially available Mo or Mo alloy.

A round bar made of a material selected from W and W alloy is perforated from one end to the other, and then rolled at a low temperature of 500 to 900"C below the recrystallization temperature. It is manufactured by rolling or forging, and then hot forging at a temperature below the recrystallization temperature.

Therefore, during the above manufacturing process, unnecessary heating above the recrystallization temperature of the crystal grains is not performed, as is the case with single-sealed pipes due to the welding process. The pipe has a low ductile-brittle transition temperature. This transition temperature is.

For example, Mo pipe, W pipe made by EB welding,
The single-sealed Fvlo pipe according to the present invention has a ductile-brittle transition temperature of 750' and 850' respectively.
In addition, the W pipe is extremely low at under 450.

It also cracks due to impact from handling during furnace construction.

No defects such as bending occur.

Furthermore, at high temperatures, the pipe portion and end portion of the single-sealed pipe according to the present invention are made of metal having the same mechanical strength, and are less susceptible to distortion or cracking due to differences in thermal expansion.

In addition, its mechanical properties are superior to EP welded single-sealed pipes in both tensile strength and elongation.

[Example] Embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a diagram showing an example of a single-sealed metal pipe according to the present invention. The single-sealed pipe in this example is made of a material that has a high melting point, high mechanical strength, and high rigidity, such as W, W alloy.

It is made of Mo, Mo alloy, etc.

The single-sealed pipe in this figure has one end 1 and the other end 2, and a tube section 3 is formed between the one end 1 and the other end 2. The illustrated pipe is sealed at one end 1.

In addition, the tube portion 3 is formed by drilling in the axial direction from the other end portion 2.

Therefore, in the illustrated single-sealed pipe, the tube portion 3 and one end portion 1 are formed of the same material, and no boundary is formed between the tube portion 3 and one end portion 1.

Next, a method for manufacturing a one-piece sealed metal pipe will be described.

First, a method for manufacturing a single-sealed metal pipe made of pure molybdenum will be explained.

A commercially available pure molybdenum round bar with a diameter of 20 mm and a length of 5 mm is prepared. This round bar has one end and the other end. This round bar was drilled with a gun drill to a predetermined length, for example, 485 m, from the other end to the one end.

FIG. 2 is a cross-sectional view of the material obtained by drilling. After drilling, a heat-resistant steel with an outer diameter of 9.5 mm is prepared for the core wire, inserted into the pipe material, and heated to 500 to 800'C. Next, it is forged to an outer diameter of 18 mm and an inner diameter of 9.5 mm. In this case, processing methods such as rolling and rolling may be used. Next, remove the core wire, prepare a heat-resistant steel core wire with an outer diameter of 911 mm, and
It is inserted into an o-pipe, heated below the recrystallization temperature, and hot-worked to produce a pipe with an outer diameter of 16 mm and an inner diameter of 9 mm. In the same manner, hot working was repeated, and a core wire with an outer diameter of 5 mm was inserted and hot worked to produce a single-sealed pipe with an outer diameter of 6 mm and an inner diameter of 5111 mm.

Next, apart from this pipe, for comparison, an outer diameter of 6 mm,
A pure molybdenum perforated pipe with an inner diameter of 5 +n and an outer diameter of 4.
A plug with a length of 95 mm and a length of 1011 times was prepared, and the hole at one end of this pipe was plugged and EB welding was performed to obtain an EB welding test piece.

Twenty single-sealed pipes obtained by the two methods described above were each prepared, and a gas leakage test was conducted at a gas pressure of 10 kg/c-. The results are shown in Table 1.

Table 1 1. Mechanical properties were tested by the following tests.

FIG. 3 is a diagram showing an example of a test piece of a hot-forged piece sealed pipe according to the present invention. In this example.

The hot-forged piece-sealed test piece had a long piece-sealed portion 4 made by the above manufacturing method.

EB welding test pieces were prepared for comparison. As shown in Fig. 4, this welded piece consists of two pure molybdenum penetrating pipes and a pure molybdenum bar made of the same material as the pipes.
20, and formed a joint 22 to be joined by EB welding so that these pipes and the bar are in a straight line. In addition, a penetrating molybdenum pipe made of the same material was prepared as a reference example.

The mechanical properties of the above three types of test pieces were measured using a universal testing machine as follows. First, a tensile test was conducted at a strain rate of 0.05/1n. The bending test was performed on each specimen with a span length of 25 mm and a crosshead speed of 1
It was held at Ryu/mln. The measured values are shown in FIG.

In this figure, one curve 11 shows the relationship between the test temperature and the bending angle of the pure Mo hot forging test specimen and the bending angle, and the other curve 12 shows the pure Mo hot forging test piece.

The relationship between the test temperature and the bending angle of the EB welded piece sealed test piece is shown. The ductile-brittle transition temperature was determined from this curve. Table 2 shows the results of the above tensile test 1 bending test.

Table 2 shows that the hot-forged single-piece sealed pipe according to the present invention has almost the same tensile strength and elongation as the through-pipe base material.2 The single-sealed pipe of the present invention has clearly superior tensile strength to the EB welded single-piece sealed pipe. It can be said that it has the mechanical property of elongation.

It was also confirmed that the ductile-brittle transition temperature of the hot-forged single-piece sealed pipe was lower than that of the EB-welded single-piece sealed pipe.

Example 2 A single-sealed pipe according to another example of the present invention was made of pure tungsten, had a structure similar to that shown in FIG. 1, and was manufactured by a method similar to that shown in FIG. Specifically, a commercially available pure tungsten round bar with a diameter of 20 mm and a length of 500 mm was drilled with a gun drill, and the core wire was then inserted.
After heat forging at 970-1170 mm, replacing the core wire with a core wire of a smaller diameter and hot working, a single-sealed pipe with an outer diameter of 6 m and an inner diameter of 5 mm as shown in Fig. 1 was manufactured.

Next, in the same manner as in Example 1, a gas leak test was conducted. As a comparative example, a single-sealed pipe test piece in which one side of a commercially available pure tungsten pipe was sealed by EB welding as in the comparative example of Example 1 was used. Table 3 shows the results.

Furthermore, mechanical properties were examined using the same test method as in Example 1. As a comparative example, an EB welding test piece made of pure tungsten prepared as shown in FIG. 4 and a commercially available through pipe test piece were also measured, and the results are shown in FIG. In this figure, curve 13 shows the test temperature and bending angle of the pure W hot-forged sealed test piece.Curve 14 shows the relationship between the test temperature and bending angle of the pure tungsten EB welded piece sealed test piece.

The ductile-brittle transition temperature was determined from this curve.

Table 4 shows the results of the above tensile test 1 bending test.

Since there is a margin below the margin, highly reliable single-sealed pipes can be manufactured without causing gas leakage due to cracks etc. in a high temperature furnace.

[Brief explanation of drawings]

FIG. 1(A) is a cross-sectional view showing a single-sealed metal pipe according to an embodiment of the present invention, FIG. 1(B) is a cross-sectional view taken along line II in FIG. 1(A), and FIG. 2(A) 1 is a cross-sectional view for explaining the present invention in detail, FIG. 2 (B) is a cross-sectional view taken along the line ■-■ of FIG. 2 (A), and FIG. 3 (A) is a test piece according to an example of the present invention. FIG. 3(B) is a cross-sectional view taken along line mm in FIG. 3(A), and FIG. 4(A) is a cross-sectional view showing a test piece of a conventional single-sealed metal pipe. Figure 4 (B) is the IV-T of Figure 4 (^)
V cross-sectional view, Figure 5. FIG. 6 is a diagram showing the ductile-brittle transition temperature of another example of the present invention. In the figure, 1 and 2 are end parts, 3 is a tube part, 4 is a sealing part 20 is a through pipe, and 22 is an EB welding part. From Table 3, even when tungsten is used as the material, there is no gas leakage from hot single-sealed metal pipes. From Table 4, the tensile strength of the hot sealed pipe is: The tensile strength is more than three times that of EB welded single-sealed pipe,
It can be seen that the single-sealed pipe of the present invention has almost the same tensile strength and elongation as the through-hole tungsten pipe, and has a much lower ductile-brittle transition temperature than the EB welded pipe. [Effects of the Invention] As described above, in the present invention, the sealing portion and the tube portion are integrally formed of the same type of metal. No cracking due to thermal expansion difference. Materials for the single-sealed pipe of the present invention include W, W alloy, and M. The single-sealed pipe of the present invention is not subjected to unnecessary high-temperature treatment such as welding or brazing, so it has a low ductile-brittle transition temperature and mechanical properties such as tensile strength and elongation. It has excellent physical characteristics. Therefore, the quality of the product is constant and the mechanical properties are also superior. 1 JiK) Figure degree 00 00 Bingen 00 Kaysu 00 ■Gengenka 000 Examination 1 degree (to 0) Procedural amendment (voluntary) October 73, 1995

Claims (3)

[Claims] (1) A single-sealed pipe having one end and the other end, a tube extending between the one end and the other end, and the one end being sealed. In the metal pipe, the sealed one end and the pipe portion are made of the same high melting point metal material, and the high melting point metal material is W, W alloy, Mo
1. A single-sealed metal pipe, which is selected from the group containing Mo alloys and Mo alloys, and has an integral structure in which the end sealing portion is not joined by welding, brazing, or the like. (2) The single-sealed metal pipe according to claim 1, wherein the single-sealed end portion and the pipe portion are integrated and have the same mechanical properties. (3) A round bar made of a high melting point metal material selected from the group including W, W alloy, Mo, and Mo alloy, and having one end and the other end, in the axial direction from the other end to one end. A hole is drilled toward the end of the hole to a length that does not reach the one end, and warm plastic working is performed at a temperature below the recrystallization temperature so that the hole is continuous with the end without welding or brazing. A method for manufacturing a single-sealed metal pipe, characterized by integrally forming a pipe portion.