JPH10244363A - High melting point metal brazed cylindrical member and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high m.p. metal-made cylindrical member for electronic parts having excellent joining strength and high dimensional precision by joining the end parts of the cylindrical plate material composed of W (alloy) and/or Mo (alloy) through a brazing filler metal adding a prescribed quantity of boron to ruthenium.molybdenum eutectic alloy. SOLUTION: The boron is added at 1.4-3.5wt.% into the ruthenium.molybdenum eutectic alloy brazing filler metal to make the brazing filler metal. The ruthenium.molybdenum eutectic alloy is desirable to be 43wt.% Ru-57wt.% Mo. At the time of adding the boron into the ruthenium.molybdenum eutectic alloy brazing filler metal, the m.p. of the brazing filler metal becomes 1420-1900 deg.C, and the m.p. becomes the desired temp. by adjusting the adding quantity of the boron. Since the brazing temp. is lowered, at the time of brazing, expensive heating furnace operation is unnecessitated. Since it is little fear that the base material becomes brittle and the strength enabling pipe drawing is provided, the cylindrical member having high dimensional precision is obtd. by using a die having suitable size and a core metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high melting point metal cylindrical member used for a high melting point metal pipe and ring for electronic parts and a method of manufacturing the same. TECHNICAL FIELD The present invention relates to a high melting point metal brazing cylindrical member formed into a cylindrical shape by a method and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in the field of electronic parts, cylindrical members such as pipes and rings made of high melting point metal have been required. For example, molybdenum (Mo) for impregnated cathode components
Cylindrical members such as pipes, tungsten (W) for power thyristors, and Mo electrode rings are used. Generally, a Mo pipe for an impregnated type cathode component is formed into a raw pipe by forming a through hole in a rod material by a gun drill or the like, and a pipe of a required size is manufactured by drawing, cutting, or the like.

[0003] Further, the W and Mo electrode rings for power thyristors are manufactured by cutting a ring shape from a plate processed by rolling or forging, or pressing and sintering into a ring shape by powder metallurgy.

[0004]

However, refractory metals such as W and Mo are both difficult-to-work metals. For example, in the case of W, a rod is formed with a through-hole by a gun drill or the like to form a pipe. Is difficult to do. Further, in the processing from the bar and the plate, the part removed by the processing is often larger than the part of the product. That is, the yield is extremely poor, the amount of resources and energy used is large, and this is a factor of high cost. Further, in the method of cutting from a plate material, the thickness of the plate material is limited to the length, and it is difficult to manufacture a long product.

[0005] On the other hand, sintered products have the advantage of greatly reducing the amount of processing, but have concerns about strength. Therefore, there is a strong demand for a method of forming a cylindrical member by joining both ends of a bent plate. For that purpose, the method of joining W and Mo becomes a problem. Depending on the application, size, and accuracy, it may be usable after joining, but in the field of electronic components and the like, the required accuracy is high, and in most cases, post-processing such as pipe drawing is performed. For example, in the case of a Mo pipe having an outer diameter of 1.5 to 2.0 mm and a thickness of 0.1 mm, an accuracy of ± 0.02 mm for the length and an accuracy of ± 0.05 mm for the thickness are required. . In that case, it is necessary to have a bonding strength that can withstand post-processing such as pipe drawing.

[0006] As a joining method that can be applied to high melting point metals such as W and Mo, arc, TIG welding (TI
G), fusion welding using a laser, an electron beam, or the like, brazing welding, diffusion bonding, mechanical joining such as riveting and bolting, and the like.

Here, fusion welding involves heating a portion of the base material to be welded, fusing the base material alone or the base material and the filler material to produce a molten metal, and solidifying and joining the molten metal. so,
Widely used in the manufacture of structures, mainly iron-based metals.
However, in the fusion welding method, it is necessary to dissolve the base material,
It is essential to heat to a temperature higher than the melting point of the base material. In addition, the dissolution and solidification of the base material are accompanied by a structural change, that is, recrystallization and coarsening thereof are inevitable, so that the residual stress and the structural change cause embrittlement near the welded portion and a decrease in strength.
Therefore, it is particularly difficult to apply to hardly weldable metals such as W and Mo which are remarkably embrittled by coarsening of crystal grains accompanying melting and solidification.

On the other hand, in diffusion bonding between W and Mo,
At a temperature higher than the recrystallization temperature, bonding becomes possible for the first time, so that embrittlement occurs due to coarsening of crystal grains. Therefore, use of an insert material such as Ni foil has been studied to reduce the joining temperature. In that case, an intermetallic compound is generated depending on the use temperature, and embrittlement occurs. For example, Ni / W generates a Ni-W metal intermetallic compound at about 1000 ° C, and Ni / Mo generates a Ni-Mo metal intermetallic compound at about 800 ° C.

[0009] Although mechanical fastening with rivets or bolts has been used for a long time and is stable in strength, it is difficult to apply it to small parts and there is a problem in the adhesion of the joining surfaces.

[0010] Further, the brazing is a metal filler metal (brazing material) having a lower melting point than the base material without melting the base material.
Is melted, and the joint is spread by using the capillary phenomenon to spread over the gap between the joint surfaces. Therefore, there are advantages such as crystal grain coarsening due to melting and solidification and embrittlement due to formation of intermetallic compounds do not occur, and thermal stress can be suppressed due to low construction temperature, and there is no structural change in the base metal. is there. Further, it is suitable for a material such as a refractory metal that requires high energy for melting a base material or a material that is liable to crack during solidification.

For example, as a brazing material for W and Mo,
Silver brazing at low temperature (800 ° C or less), Ru- at high temperature.
Mo eutectic alloy brazing material is used. Of these brazing materials, silver brazing cannot be used at high temperatures because of its low brazing temperature, and it is impossible to perform pipe drawing at a hot temperature. In addition, the use of a material having a melting point or lower has a further lowering of the softening temperature, so that there is a great concern that the strength is reduced.

On the other hand, in the case of the Ru—Mo eutectic alloy brazing material, there is little concern about a decrease in strength at high temperatures, but since the brazing temperature is as high as 2000 ° C., embrittlement of the W and Mo base materials becomes a problem. Since there is a serious problem in practical use, such as the inability to perform pipe drawing after welding, a brazing material having a low brazing temperature and a high joining strength is desirable as long as there is no problem in using brazing members.

Therefore, the technical problem of the present invention is to make the construction extremely simple in practical use, to reduce the risk of embrittlement of the base material, to provide high bonding strength, and to achieve high dimensional accuracy. An object of the present invention is to provide a brazed cylindrical member and a method for manufacturing the same.

[0014]

As a high-temperature brazing material for W and Mo, for example, a Ru-Mo eutectic alloy brazing material having excellent wettability to W and Mo is known. Has a high melting point of 1955 ° C., and there are many problems in strength reduction and construction due to embrittlement of the W and Mo base materials.

The present inventors have experimentally found that by adding boron (B) to the Ru-Mo eutectic alloy brazing material, the melting point can be adjusted without impairing the wettability, and the present invention is made. It has been reached.

That is, according to the present invention, the ends of at least one material obtained by bending a flat plate are formed of at least one of W, Mo, and respective alloys. A refractory metal brazing cylindrical member characterized by being joined via a brazing material is obtained.

According to the present invention, in the high melting point metal brazing cylindrical member, the brazing material may contain ruthenium-molybdenum (Ru-Mo) eutectic alloy containing boron (B) in an amount of 1.4% by weight. A refractory metal brazed cylindrical member substantially obtained by adding 3.5% by weight is obtained.

Further, according to the present invention, a plate made of at least one of W, Mo and each of the alloys is subjected to a bending process, and the ends of at least one of the plates are brazed through a brazing material. Thereafter, a method for producing a refractory metal brazed cylindrical member characterized by performing pipe drawing is obtained.

Further, according to the present invention, a plate made of at least one of W, Mo and respective alloys is provided.
A method for producing a refractory metal brazed cylindrical member is characterized by performing bending, brazing the ends of at least one of the plate members via a brazing material, and then performing machining.

[0020]

Embodiments of the present invention will be described below.

FIGS. 1 to 3 show various examples of a high melting point metal brazing cylindrical member according to an embodiment of the present invention.

The refractory metal brazing cylindrical member 10 according to the example of FIG. 1 is formed by bending a plate material 1 made of W, Mo, and at least one of the alloys thereof into a circular shape. And the end faces 3a, 3b of the straight portions are Ru.
-Butted and joined via the brazing material 2 made of -Mo. Further, post-processing such as pipe drawing or mechanical processing such as polishing may be performed.

The refractory metal brazing cylindrical member 11 according to the example of FIG. 2 is a semicircle made of two plates 1, 1 'made of W, Mo and at least one of the respective alloys. The end portions 3a, 3b and 3b ', 3a' of the straight portions 3a, 3b of the respective plate members 1, 1 'are butted and joined via brazing materials 2, 2' made of Ru-Mo, respectively. . The refractory metal brazed cylindrical member according to this example may be subjected to post-processing such as pipe drawing or mechanical processing such as polishing, as in the example of FIG.

The refractory metal brazing cylindrical member 12 according to the example of FIG. 3 is formed by bending a plate material 1 made of at least one kind of refractory metal of W, Mo, and respective alloys into a circular shape. Is applied, and both ends are overlapped, and Ru-M
o, and joined via a brazing material 2. further,
Similar to the examples of FIGS. 1 and 2, post-processing such as pipe drawing or mechanical processing such as polishing may be performed.

FIG. 4 is a view showing the characteristics of the brazing material used for producing the cylindrical member having a high melting point metal brazing shown in FIGS. As shown in FIG. 4, the melting point of the Ru and Mo brazing materials can be lowered by increasing the amount of boron (B) added.

The composition range of the base Ru and Mo brazing filler metal can be 33.5 to 49.5% by weight of Ru.
Here, the Ru-Mo brazing material is Ru, in this range.
It has a Mo eutectic structure and has a eutectic point of 43% by weight.
Ru-57% by weight Mo is desirable.

Further, it is possible to adjust the brazing temperature by adding boron (B) to the Ru, Mo eutectic alloy brazing material in a desired temperature within a temperature range of 1420 ° C. to 1900 ° C. Become.

For example, the addition amount of B is 3.5% by weight and the melting point is about 1420 ° C., 2.5% by weight and the melting point is about 1650 ° C.
A melting point of about 1900 ° C. at 1.4% by weight can be selected.

The brazing temperature is about 30 to 50 ° C. from the melting point.
It may be set higher, but may be changed depending on the work size or the heating method.

The method of applying the brazing material in the form of a paste with an organic solvent is simple, but the brazing material may be formed into a thin plate or a rod by pressing or extrusion. If necessary, a binder such as paraffin may be mixed at the time of molding. The binder may be used for forming ordinary W, Mo or cemented carbide, and the same applies to the conditions for debinding.

By joining the butted or overlapped portions of the bent material using the above brazing material, a cylindrical member having excellent joining strength can be manufactured. The bent shape may be formed into a gutter shape, a C-shaped shape, or the like by hot bending, pressing, or a forming roll. Depending on the application, size, and accuracy, it can be used after joining, but post-processing such as pipe drawing may be performed. In the above brazing materials, the melting point can be selected, so that the brazing temperature can be kept low, and because the heating time during brazing is short, embrittlement due to recrystallization of the base material can be reduced. Has bonding strength that can withstand processing. Therefore, post-processing such as pipe drawing becomes possible.

In general, pure molybdenum is selected as the Mo base material in view of its workability and cost.
Its recrystallization temperature is as low as about 1000 ° C. As a molybdenum material used at a higher temperature, for example, TZM containing Ti, Zr, and C is known. In TZM, the recrystallization temperature is only 1300 to 1500 ° C., but the brazing material of the present invention is used. By using, the melting point of the brazing material can be selected, so that the brazing temperature can be kept low.
In addition, since the heating time during brazing is short, embrittlement due to recrystallization at the time of joining the molybdenum or TZM base material can be reduced.

Further, as a molybdenum material having excellent workability and high temperature deformation resistance even after the recrystallization temperature, there is molybdenum containing lanthanum (Japanese Patent Publication No. 2-38659). This molybdenum containing lanthanum is 0.1 ~
Less than 1.0% by weight of lanthanum or lanthanum oxide;
The molybdenum alloy is composed of molybdenum, and has crystal grains exhibiting an interlocking structure, which are substantially elongated in a certain direction and recrystallized, and are excellent in workability and high-temperature deformation resistance. By using this lanthanum-containing molybdenum as a material, there is no embrittlement even when a brazing material with a higher melting point is used, and the amount of deformation at a higher temperature than when pure molybdenum is used as a material is reduced. Can be smaller.

By performing the brazing process using the above-mentioned brazing material, that is, a brazing material having a melting point suitable for the operating temperature of the brazing member, it is possible to reduce the number of cases compared with the case where a Ru-Mo eutectic alloy brazing material that has been used in the past is used. Since the brazing temperature can be lowered, it is not necessary to use an expensive ripening furnace capable of heating at 2000 ° C. or more for brazing of high melting point metal, and the degree of freedom of the furnace structure and the heating method is increased. It is possible to provide a brazed cylindrical member which is very easy to construct and has little risk of embrittlement of the base material. Furthermore, a cylindrical member with high dimensional accuracy can be obtained by using a die and a core metal of appropriate size because it has a strength capable of pipe drawing.

Hereinafter, a specific example of the production of the high melting point metal brazed cylindrical member of the present invention will be described.

(First Embodiment) Plate thickness 1 mm, width 1
Two Mo plates having a diameter of 2.5 mm and a length of 200 mm and processed into a gutter shape with an outer radius of 4 mm by hot pressing were prepared, and used as base materials 1 and 2. 41. Melting point is about 1420 ° C. at the end face of the longitudinal straight portion of the base material 1 After applying a brazing material powder made of a brazing material powder consisting of 5% by weight of Ru-55.0% by weight and Mo-3.5% by weight of B with a binder, the base material 2 is set, and the end faces are interposed with the brazing material therebetween. Match
15 ° C / min in Ar atmosphere furnace
The temperature was raised to 1450 ° C. at a temperature rising rate of 5 ° C., and the temperature was maintained for 5 minutes, followed by slow cooling to complete joining of a pipe having an outer diameter of about 8 mm and a length of 200 mm.

After this joining process, it was confirmed by visual inspection that the brazing material had sufficiently flowed into the gaps in the base material, that no voids existed, and that a very good joining condition was obtained. Pipe. In hot pipe drawing, the core metal and the die are sequentially reduced, the pipe is drawn to a final size of 1.6 mm in outer diameter and 0.10 mm in wall thickness, and then cut into 3.4 mm in length to form a pipe and a barrel to remove cutting burrs. The pipe was polished, and held at 950 ° C. for 10 minutes to remove distortion in a pipe drawing process, thereby producing a pipe-shaped member having a shape as shown in FIG. The appearance was inspected with a 20 × optical microscope, and it was confirmed that there was no processing defect such as a crack. As a result, the required accuracy length is 3.4 ± 0.02 mm
+ 0.015mm, 0.010mm, wall thickness 0.1
+0.003, -0.004 for 0 ± 0.005mm
mm, satisfying the required accuracy.

Further, a radial crushing strength test of the present pipe-shaped member was conducted based on JIS Z2507. The joining position was adjusted to 0 ° and 90 ° with respect to the load direction, and the average radial crushing strength of a total of 10 test pieces of 5 pieces each was 971.9 MPa, the maximum strength was 1049.0 MPa, and the minimum strength was 949.4 MPa.
Met. There was no difference depending on the direction of the joining position.

Next, this pipe-shaped member was compared with a pipe of the same size manufactured by a usual drawing process which is practically used as a Mo pipe for electronic parts. That is, the outer diameter 8
6mm inside diameter with gun drill for Mo, 200mm length Mo
mm hole was used as a blank pipe, and heat pipe drawing was performed in the same manner as in 1 above to obtain an outer diameter of 1.6 mm, a wall thickness of 0.1 mm, and a length of 3.4 mm.
Was manufactured. The result of testing the radial crushing strength of this member by the above-mentioned test method was an average radial crushing strength of 983.7MP.
a, maximum strength 1003.8 MPa, minimum strength 961.8
MPa.

That is, the pipe-shaped member subjected to hot drawing after brazing has dimensional accuracy and strength enough to be practically used as a Mo pipe for electronic parts.

(Second Embodiment) Similar to the first embodiment, a lanthanum-containing molybdenum (see Japanese Patent Publication No. 2-38659) having a thickness of 1 mm, a width of 12.5 and a length of 200 mm is hot-pressed. Two pieces processed into a gutter shape having an outer radius of 4 mm by press working were prepared and used as base materials 1 and 2. The melting point is about 1900 ° C on the end face of the long straight part of the base material 4
2.4% by weight Ru-56.2% by weight Mo-1.4% by weight
After applying the brazing material obtained by converting the brazing material powder of B into a paste with a binder, the base material 2 is set, the end faces are butt-bonded to each other via the brazing material, and the positional displacement is reduced by a jig. The temperature was raised to 1950 ° C. at a rate of 15 ° C., kept at this temperature for 5 minutes, and then gradually cooled to obtain an outer diameter of about 8 mm and a length of 200 mm.
The joining of the mm pipe was completed.

After this joining process, it was confirmed by visual inspection that the brazing material had sufficiently flowed into the gaps in the base material, that no voids existed, and that a very good joining condition was obtained. Pipe. In hot pipe drawing, the core metal and the die are successively reduced, the pipe is drawn to a final size of 1.6 mm in outer diameter and 0.1 mm in thickness, then cut to 3.4 mm in length, barrel-polished, and further drawn. 1 at 950 ° C to remove strain
After holding for 0 minutes, a pipe-shaped member having the shape shown in FIG. 2 was manufactured. The appearance was inspected with a 20 × optical microscope, and it was confirmed that there was no processing defect such as a crack. As a result, the required accuracy length is 3.
+ 0.013mm, -0.01 for 4 ± 0.02mm
± 0.0 for 1mm, wall thickness 0.10 ± 0.005mm
It was within the range of 03 mm, which satisfied the required accuracy. Further, the radial crushing strength test of this pipe-shaped member is performed according to JIS Z250.
7 was examined. The average radial crushing strength of the ten test pieces was 1109.9 MPa, the maximum strength was 1130.0 MPa, and the minimum strength was 1091.4 MPa. It turned out to have.

(Third Embodiment) Similar to the first embodiment, a W plate having a thickness of 1 mm, a width of 12.5 mm and a length of 200 mm is formed on a gutter having an outer radius of 4 mm by hot pressing. Were prepared as base materials 1 and 2. 41. Melting point is about 1600 ° C. on the end face of the longitudinal straight portion of the base material 1
8% by weight of Ru-55.4% by weight of Mo-2.8% by weight of B, and then applying a brazing material in the form of a paste with a binder, and then setting the base material 2 and joining the end faces via the brazing material. And the jig is used to prevent misalignment. The temperature is raised to 1650 ° C. in a vacuum furnace at a rate of 15 ° C. per minute, and the temperature is maintained for 5 minutes, followed by slow cooling to an outer diameter of about 8 mm and a length of 200 mm. Completed the joining of the pipes.

After this joining process, it was confirmed by visual inspection that the brazing material had sufficiently flowed into the gaps between the base metals, that no voids existed, and that a very good joining condition was obtained. The pipe was used for drawing. In hot pipe drawing, the core metal and the die are successively reduced, drawn to a final size of an outer diameter of 2.0 mm and a wall thickness of 0.2 mm, cut to a length of 5 mm, barrel-polished, and further strained in the pipe drawing process. The sample was held at 1200 ° C. for 10 minutes for removal to produce a pipe-shaped member having the shape shown in FIG. The appearance was inspected with a 20 × optical microscope, and it was confirmed that there were no processing defects such as cracks.

For comparison, an attempt was made to produce a pipe-shaped member of the same size by pipe drawing from a W round bar. 8mm outside diameter,
A 200 mm long W rod was bored with a gun drill with an inner diameter of 6 mm under different cutting conditions, but was not possible.
W is a difficult-to-machine material, and the difficulty of deep hole machining was confirmed. Therefore, it was impossible to manufacture a W pipe for pipe drawing, that is, to manufacture a W pipe by the pipe drawing method.

(Fourth Embodiment) A Mo plate having a thickness of 6.5 mm, a width of 12 mm and a length of 270 mm is formed into a C-shape by hot bending in which a material is wound around a metal mold. Polishing correction processing was performed so as to be parallel. 41.8% by weight having a melting point of about 1600 ° C. on the end face of the straight portion of the base material
After applying a brazing filler metal made of Ru-55.4 wt% Mo-2.8 wt% B into a paste with a binder, the end surfaces are butted together via a brazing filler metal, and misaligned with a jig. And deformation, 1 minute per minute in a vacuum furnace
The temperature was raised to 1650 ° C. at a rate of 5 ° C., held at this temperature for 5 minutes, and then gradually cooled to complete the joining. Thereafter, the outer diameter 90 mm and the inner diameter 80 m having the shape shown in FIG.
m, a ring having a height of 10 mm was completed. In lathe processing, there was no problem in workability such as breakage, and in the visual appearance inspection, the brazing material flowed sufficiently in the gaps in the base material, there were almost no voids, and a very good joining condition was obtained. From the cross-section observation, it was confirmed that the base metal was not damaged.

(Fifth Embodiment) A sheet having a thickness of 1.0 mm, a width of 8 mm, and a length of 265 mm is formed into a C-shape by hot bending processing in which a material is wound around a mold. Polishing correction processing was performed so that On the end face of the straight portion of the base material, 41.8 wt% Ru- having a melting point of about 1600 ° C.
After applying a brazing material powder made of 55.4% by weight Mo-2.8% by weight B into a paste with a binder, the end faces are butted against each other to prevent displacement and deformation with a jig, and the vacuum furnace is used. 1650 at a rate of 15 ° C per minute in
C., held at this temperature for 5 minutes, and then gradually cooled to complete the joining. The inner diameter was 84 mm having a shape as shown in FIG.
A ring having a thickness of 1.0 mm and a height of 8 mm was completed. A visual appearance inspection confirmed that the brazing filler metal had sufficiently flowed into the gap between the base metals, that there were almost no voids, and that a very good joint was obtained. Furthermore, it was confirmed from the cross-section observation that the base material was not damaged.

Further, a heat cycle test was performed. A cycle in which the temperature was raised from room temperature to 1500 ° C. at a rate of 15 ° C. per minute, held for 20 minutes and then cooled in a furnace was repeated 10 times, and the deformation of the ring was measured. As a result of the measurement of five samples, the warp in the thickness direction and the coaxiality in the radial direction were 18 μm at the maximum, which is the required accuracy of the spacer for heat treatment such as ceramic firing.
It was 20 μm or less, confirming that it can be used for this application.

[0049]

As described above, according to the present invention, it is possible to manufacture a high melting point metal brazing cylindrical member for electronic parts having high joining strength and high dimensional accuracy. In other words, it is no longer necessary to use an expensive heating furnace capable of heating at 2000 ° C. or higher for brazing of a high melting point metal, so that the degree of freedom of the furnace structure and the heating method is increased, and practically very simple construction is achieved. It is possible to provide a high melting point metal brazing cylindrical member having a low possibility of embrittlement of a base material and a method of manufacturing the same.

Further, according to the present invention, a high melting point metal brazing cylindrical member having high dimensional accuracy and a method of manufacturing the same can be obtained by using a die and a core metal of appropriate size because of having a strength capable of forming a pipe. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a cylindrical member having a refractory metal brazing shape according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another example of the high melting point metal brazing cylindrical member according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing another example of the high melting point metal brazing cylindrical member according to the embodiment of the present invention.

FIG. 4 is a graph showing a change in melting point of a Ru—Mo brazing material with respect to an amount of boron added.

[Explanation of symbols]

 1, 1 'plate material 2, 2' brazing material 3a, 3b, 3a ', 3b' straight end face 10, 11, 12 high melting point metal brazing cylindrical member

Claims (4)

[Claims] 1. A cylindrical plate made of at least one of W, Mo and respective alloys, wherein ends of at least one material obtained by bending a flat plate are joined to each other via a brazing material. A high melting point metal brazing cylindrical member characterized by being formed. 2. The refractory metal brazed cylindrical member according to claim 1, wherein the brazing material is a ruthenium-molybdenum (Ru-Mo) eutectic alloy containing 1.4% by weight of boron (B).
A refractory metal brazed cylindrical member characterized in that the member is substantially composed of a metal having a melting point of 3.5 to 3.5% by weight. 3. A plate made of at least one of W, Mo and an alloy thereof is subjected to a bending process, and ends of at least one of the plates are brazed through a brazing material, and then subjected to a pipe drawing process. A method for producing a refractory metal brazed cylindrical member, characterized by performing the following. 4. A plate made of at least one of W, Mo and each of the alloys is subjected to a bending process, and at least one end of said plate is brazed through a brazing material, followed by machining. A method for producing a refractory metal brazed cylindrical member, characterized by performing the following.