JP2592372B2 - Manufacturing method for dissimilar joints - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dissimilar joint made of stainless steel or a nickel-based alloy and a zirconium-based material or a titanium-based material.

[0002]

2. Description of the Related Art Pure zirconium alloys (zirconium-based materials) such as pure zirconium and zircaloy, and pure titanium and Ti
Titanium alloys (titanium-based materials) such as -5% Ta are widely used as structural materials for nuclear reactors and their surroundings because of their excellent corrosion resistance and extremely small thermal neutron absorption area. On the other hand, in a nuclear plant such as a nuclear power plant, in consideration of economy, high corrosion-resistant stainless steel, Inconel (trade name), etc. are used only for structures that are in a relatively moderate operating environment. Are also widely used. Therefore, in a nuclear plant,
It is necessary to reliably perform dissimilar material joining between a zirconium-based material or a titanium-based material and a stainless steel or a nickel-based alloy.

As a simple joining method applicable to such dissimilar material joining, there is a method using a flange joint. However, this method has a drawback that it is difficult to ensure the sealing performance at the joint site, and particularly in applications where strict prevention of leakage over a long period of time is required, such as in the case of joining tubes in a nuclear power plant. Is not suitable.

[0004] Another commonly employed joining method is welding. When welding is performed between a zirconium-based material or a titanium-based material and stainless steel or a nickel-based alloy, the former component is used. (Zr) and titanium (Ti), and the latter components iron (Fe), nickel (Ni) and chromium (Cr) concentrate at the weld site, resulting in a very brittle intermetallic compound (ZrFe ₂ , TiFe, etc.), and the corrosion resistance and ductility are significantly reduced. Therefore, in the above-described dissimilar material joining in a nuclear power plant in which safety is most important, direct welding between the two cannot be adopted.

Therefore, in dissimilar material joining between a structural material made of a zirconium-based material or a titanium-based material and a structural material made of stainless steel or a nickel-based alloy in a nuclear power plant, conventionally, the same type of material as each of the two structural materials has been used. Dissimilar material joints in which members are integrated by solid-phase bonding are used. Joining by this dissimilar material joint is realized by welding the same type of structural material to each end of the two members, and since these weldings are performed between the same type of materials, there is no problem in strength, and Since a solid joining state is obtained by solid-phase joining between the two members of the joint, dissimilar material joining with high reliability is possible.

In the manufacture of this kind of dissimilar material joint, it is necessary to realize strong solid-phase joining.
No. 96 discloses a first member made of a Ti-based alloy other than β-type Ti or a Zr-based alloy other than β-type Zr, and a second member made of stainless steel, and a β-type Ti-based alloy made between them. Alternatively, a method is disclosed in which an insert material made of a β-type Zr-based alloy is interposed, and further heated to a temperature lower than the β transformation point of the first member, and diffusion bonding is performed by hot isostatic pressing.

In this method, the constituent elements of each of the first member and the second member are dissolved in the insert material, and a strong joint state excellent in corrosion resistance and bending ductility is obtained between the two members. As described above, there is a limit in improving the productivity in the manufacturing process, and it is difficult to reduce the product price.

Japanese Patent Application Laid-Open No. 2-55682 discloses that a joining surface of both members to be solid-phase joined is inclined with respect to a pressing direction at the time of joining, and an insert is formed by pressing the joining surfaces. There is disclosed a method for performing solid-phase joining without requiring any interposition of materials.

However, the dissimilar material joint obtained by this method has a problem in corrosion resistance at the joint, it is difficult to apply it to a severe use environment inside a nuclear power plant, and it is disclosed in the above-mentioned JP-A-61-52996. As with the method, there is a problem that the improvement in productivity is limited and it is difficult to reduce the product price.

Therefore, the present applicant has proposed a method of manufacturing a dissimilar joint for the purpose of improving productivity, which is a common problem of the above two methods. This method uses a zirconium-based material or titanium as disclosed in JP-A-2-169191.
Inner layer material of circular section made of tan-based material and stainless steel
Or a cylindrical outer layer made of nickel-based alloy, or
Is a circular section made of stainless steel or nickel-based alloy.
Inner layer material and zirconium-based material or titanium-based material
After forming a clad material by interposing an intermediate layer made of tantalum between them and obtaining a clad material, this is heated to 800 to 1200 ° C. The outer layer material and the tantalum layer are formed at one end of this clad material, and the inner layer material is formed at the other side end by performing drawing reduction rolling of the outer diameter with a surface reduction rate of 65% or less using This is a method of obtaining a dissimilar material joint by removing each tantalum layer. Further, by perforating the inner layer material, a dissimilar material joint for joining pipes can be obtained.

That is, in this method, the inner layer material and the outer layer material are solid-phase bonded by a continuous rolling process using an inclined rolling mill, and this is appropriately cut, and at both ends, the above-mentioned layers for removing each layer are removed. Since a desired dissimilar material joint can be obtained by performing appropriate processing, the productivity can be significantly improved as compared with the above-described two methods that require pressing of individual members.

[0012]

As described above, Japanese Patent Laid-Open No. 2-16
The method disclosed in No. 9191 is an excellent method in terms of productivity, but may not provide satisfactory joint strength and corrosion resistance to a dissimilar joint obtained as a product.

In actual production, a clad material is obtained by winding a tantalum foil around the outer periphery of the inner layer material so as to form an intermediate layer and fitting these to a cylindrical outer layer material.
The joining strength and corrosion resistance of the product joint depend on the fitting condition at this time, and are also affected by the setting of the subsequent heating and drawing rolling. JP-A-2-
In the method disclosed in No. 169191, the fitting conditions are not specified, and the heating and rolling conditions are loosely specified, so that a good diffusion bonding state is obtained in the clad material obtained after the end of the drawing rolling. However, the unjoined portion or joining strength that occurs locally causes insufficient strength and poor corrosion resistance of the product joint.

The present invention has been made in view of such circumstances, and further develops the method proposed in Japanese Patent Application Laid-Open No. 2-169191 to produce a dissimilar joint having excellent joining strength and corrosion resistance with high productivity. It is an object of the present invention to provide a method of manufacturing a dissimilar joint.

[0015]

According to the present invention, there is provided a method for manufacturing a dissimilar joint, comprising the steps of: providing a zirconium-based material or a titanium-based material;
Stainless steel or nickel
A cylindrical outer layer material made of Kel-based alloy or stainless steel
Inner layer material with circular cross section made of stainless steel or nickel-based alloy
And a circle made of zirconium-based material or titanium-based material
A cylindrical outer layer material, and a clad material is formed by fitting an intermediate layer made of tantalum between the two to form a clad material, and heating the clad material to a predetermined temperature and drawing and rolling the outer diameter to form the clad material. None, a method of manufacturing a dissimilar joint in which an outer layer material and an intermediate layer are removed at one end of the clad material and an inner layer material and an intermediate layer are removed at the other end, respectively, wherein the outer layer material and the inner layer material are fitted. The clearance ratio C between the two,
With respect to the rolling ratio A during the reduction rolling, C ≦ 1.2 × A + 0.
Set to the range of 92 (%), and set the inside of these to 1 × 10 ^-2 To
rr and a vacuum degree of not more than rr.
The temperature is set to a range of 00 ° C., and the reduction is further reduced by 5% to 40% by an inclined rolling mill equipped with three or more cone-shaped rolls.
It is characterized in that it is carried out at a reduced area ratio.

[0016]

According to the present invention, firstly, a cylindrical outer member having an internal diameter of at d _1, the inner layer material of circular cross-section having an outer diameter becomes d _2, by the d ₁ from the d ₂ Tokyo (1) The clearance ratio C obtained is fitted to the rolling ratio A at the time of the drawing reduction in the subsequent step under the condition that the equation (2) is satisfied, and the inside of these is vacuumed to 1 × 10 ^-2 Torr or less. To keep the cladding material closed. C = {(d ₁ −d ₂ ) / 2d ₁ } × 100 (%) (1) C ≦ 1.2 × A + 0.92 (%) (2)

Next, the clad material is heated at 800 to 1000 ° C.
, And supplied to an inclined rolling mill equipped with three or more cone-shaped rolls, and the outer diameter is reduced at a reduction ratio of 5% to 40% to obtain a clad material. The outer layer material and the intermediate layer are removed at one end and the inner layer material and the intermediate layer are removed at the other end, respectively, to produce a dissimilar material joint.

By the above-described settings of the clearance ratio C at the time of fitting, the degree of vacuum inside the clad material, and the reduction of area at the time of rolling, a favorable condition can be obtained between the tantalum as the intermediate layer and the inner and outer layer materials. A diffusion bonding state is obtained. Further, by the above-described setting of the heating temperature, a Ta-Fe-based or brittle
Generation of a Ta-Ni-based intermetallic compound is suppressed. Furthermore, 3
The adoption of an inclined rolling mill equipped with more than one cone-type roll prevents the occurrence of internal cracks due to Mannesmann destruction.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a front sectional view of a clad material used in a method for manufacturing a dissimilar joint according to the present invention (hereinafter, referred to as the method of the present invention), and FIG. 2 is a partially broken side view of the same.

As shown in FIG. 1, the clad material 10 is made of zircon
An inner layer material 11 having a circular cross section made of a titanium-based material or a titanium-based material and a cylindrical outer layer material 12 made of stainless steel or a nickel-based alloy were fitted to each other via a thin intermediate layer 13 made of tantalum. Then, as shown in FIG.
Open the openings at both ends of each of the lid plates made of the same material
The structure is closed by 12a and 12b. In addition, inner layer material
11 is not limited to a solid material as shown, but may be a hollow material. Also, the material of the inner layer material 11 and the material of the outer layer material 12 are reversed,
That is, the inner layer material 11 is made of stainless steel or a nickel-based alloy.
The outer layer material 12 is made of a zirconium-based material or a titanium-based material.
There may be.

In the method of the present invention, the fitting of the inner layer material 11 and the outer layer material 12 is performed later with a clearance ratio C determined by the formula (1) based on the inner diameter d _{1 of} the latter and the outer diameter d _{2 of the} former. The rolling ratio A in the reduction rolling is set so as to satisfy the condition shown in the expression (2). C = {(d ₁ −d ₂ ) / 2d ₁ } × 100 (%) (1) C ≦ 1.2 × A + 0.92 (%) (2)

The above fitting conditions are set so as to obtain a good diffusion bonding state between the inner layer material 11 and the outer layer material 12 and the intermediate layer 13 by drawing rolling in a later step. The reason will be described later.

The inside of the clad material 10 sealed by the cover plates 12a and 12b is maintained at a vacuum of 1 × 10 ⁻² Torr or less. Such a degree of vacuum suppresses the formation of oxide at the interface between the inner layer material 11 and the outer layer material 12 in the next heating step, and provides good diffusion bonding between the inner layer material 11 and the outer layer material 12 and the intermediate layer 13. Necessary to get the condition,
The reason for limiting the upper limit vacuum degree (= 1 × 10 ⁻² Torr) will be described later.

The fitting of the inner layer material 11 and the outer layer material 12 with the intermediate layer 13 interposed is performed by the inner layer material 11 and the outer layer material.
12 is degreased and washed, and the same degreased and washed Ta foil is wrapped around the outer periphery of the inner layer material 11, and these are fitted into the outer layer material 12. This is achieved by maintaining the degree of vacuum inside the clad material 10. The sealing by the cover plates 12a and 12b is achieved by performing electron beam welding in a vacuum chamber maintained at a predetermined degree of vacuum.

The clad material 10 configured as described above is
After being heated in a heating furnace (not shown), it is fed to a tilt rolling mill. FIG. 3 is a schematic side view of a tilt rolling mill used for carrying out the method of the present invention, FIG. 4 is a front view taken along line IV-IV in FIG.
FIG. 5 is a plan view for explaining the inclination angle β.

As shown in FIG. 3 and FIG.
It comprises three rolls 1, 2, 3 arranged around a pass line XX of a clad material 10 as a rolled material. These rolls 1, 2, 3 are provided with inlet surfaces 1 b, 2 b, 3 b which are expanded from the entrance side to the exit side of the clad material 10 fed along the pass line XX, and the diameter expansion ratio. And the short exit surfaces 1c, 2c, 3c connected to the exit side, and the gorge portions 1a, 2
a, 3a, respectively, and is a cone-shaped roll having a conical shape as a whole. An intersection point O (roll setting center) between a plane including the gorge parts 1a, 2a, 3a and each axis YY is set. ,
In a plane orthogonal to the pass line XX, they are arranged so as to be evenly distributed on a predetermined circumference centered on the pass line XX.

The axis Y of each of the rolls 1, 2, 3
-Y is a clad material in a side view as shown in FIG.
For the 10 pass lines XX, enter the pass line XX
5 and a predetermined angle (crossing angle γ), and as shown in FIG. 5, a predetermined angle (inclination angle β) on the same side with respect to the pass line XX of the clad material 10 in plan view as shown in FIG. ).

The rolls 1, 2, and 3 are connected to a drive source (not shown), and are driven to rotate in the same direction about the respective axis YY as shown by arrows in FIG. It is done. Thus, the clad material 10 fed to the inclined rolling mill along the pass line XX includes the rolls 1, 2, 3
The rotation of these rolls 1, 2, 3, which is bitten in between and tilts with respect to the pass line XX, imparts a rotational force around the axis and an advancing force in the axial direction. Will move in a spiral along the
3, the outer diameter is reduced by the action of the inlet faces 1b, 2b, 3b and the shape is adjusted by the action of the outlet faces 1c, 2c, 3c, as shown in FIG. 3, and is determined at the gorge portions 1a, 2a, 3a. The clad material 14 having an outer diameter is sent out.

The above description has been made on the case where the inclined rolling mill provided with the three cone-shaped rolls 1, 2, and 3 is used. However, in the practice of the present invention, four cone-shaped rolls are used. May be used, and although not practical, a tilting mill having five or more cone-shaped rolls may be used. In the case of rolling by an inclined rolling mill having two rolls, there is a high probability that an internal crack occurs in the clad material 14 due to the influence of Mannesmann destruction caused by deformation between the rolls, and the reliability of the product is regarded as important. Application to the method of the present invention is not desirable.

During this rolling, the tantalum intermediate layer 13 interposed between the inner layer material 11 and the outer layer material 12 forms a fragile intermetallic compound between the inner layer material 11 and the outer layer material 12 made of dissimilar metals. The effect of suppressing the formation of slag and promoting diffusion bonding between the inner layer material 11 and the outer layer material 12 is achieved.

In the method of the present invention, the clad material
The clad material 14 is obtained by the inclined rolling of 10. As another rolling method, there is a groove rolling method, which is a method of performing multi-pass rolling by a roll arrangement having a diamond square hole shape or an oval round hole shape, and a cross-sectional shape in the middle of reduction in each pass. Has a non-circular cross section. Therefore, the inner layer material
When applied to a composite material (clad material 10) in which the deformation resistance difference between 11 and the outer layer material 12 is extreme, the inner layer material 11 extends in the rolling direction,
The outer layer material 12 tends to extend in the direction perpendicular to the rolling direction, and a gap is generated between the inner layer material 11 and the outer layer material 12 for each pass, so that the clad is securely joined in the circumferential direction. Lumber
14 is not obtained.

As described above, by the action of the intermediate layer 13 in the clad material 10 and the adoption of the inclined rolling method, a good diffusion bonding state is obtained between the inner layer material 11 and the outer layer material 12, and the bonding strength and the corrosion resistance are improved. An excellent clad material 14 can be obtained.

The rolling conditions for the above-described reduction rolling are set as follows. (B) The clad material 10 before rolling is heated to a temperature range of 800 ° C to 1000 ° C. (B) The area reduction rate determined by the following equation is 5% to 40%. Area reduction = {(A ₀ −A ₁ ) / A ₀ } × 100 (%) (3) where A ₀ is the cross-sectional area before rolling, that is, the cross-sectional area of the clad material 10, and A ₁ is the cross-sectional area after rolling. The sectional area, that is, the sectional area of the clad material 14. (C) Do not perform reheating rolling.

The reasons for setting these conditions will be described.
First, the upper limit of the heating temperature was set to 1000 ° C., when the temperature of the clad material 10 during rolling exceeded 1000 ° C., the inner layer material 11
And there is a possibility that a fragile intermetallic compound such as Ta-Fe or Ta-Ni may be generated at a bonding interface between the outer layer material 12 and the intermediate layer 13 interposed therebetween, and the corrosion resistance of the bonding interface is reduced. To do that. On the other hand, the reason why the lower limit of the heating temperature is set to 800 ° C. is that if the temperature of the clad material 10 during rolling is lower than 800 ° C., the bonding strength at the bonding interface becomes insufficient, and the pressure is 20 kgf / mm ² In order to secure the above bonding strength, it is necessary to set a lower limit temperature of 800 ° C.

The upper limit of the area reduction rate determined by the equation (3) is set to 40% because when the reduction rolling is performed at the area reduction rate exceeding this, the inner layer material inside the clad material 14 after the rolling is performed. This is because the shape change of 11 is so large that a circle cannot be maintained, and it is not possible to maintain a predetermined dimensional accuracy on the side from which the outer layer material 12 and the intermediate layer 13 have been removed in the next step as described later. On the other hand, the reason why the lower limit of the area reduction rate is set to 5% is that when the reduction rolling is performed at a reduction area lower than this, the inner layer material 11 and the outer layer material 12 are interposed between the rolls 1, 2, and 3 when the rolling is performed. This is because pressing with the layer 13 is insufficient, and sufficient bonding strength at the bonding interface cannot be obtained.

Furthermore, the reason why the reheating rolling is not performed is that the formation of intermetallic compounds at the bonding interface between the inner layer material 11 and the outer layer material 12 and the intermediate layer 13 is promoted by the reheating, and the corrosion resistance at the bonding interface is reduced. It is because it falls. This also occurs due to reheating performed under the temperature conditions described above.

The rolling ratio A in the above equation (2) is obtained by the following equation using the cross-sectional areas A ₀ and A ₁ before and after the above-mentioned rolling. A = A ₀ / A ₁ (4)

The clad material 14 obtained as described above is cut to an appropriate length on the output side of the inclined rolling mill, and then the outer layer material 12 and the intermediate layer 13 are provided on one end and the clad material 14 is provided on the other end. The inner layer material 11 and the intermediate layer 13 are removed respectively, as shown in FIG.
A dissimilar joint 14A is formed in which the inner layer material 11 and the outer layer material 12 are exposed on both sides of the joint portion remaining at the center. The illustrated dissimilar material joint 14A is made of a tube material Q made of a zirconium-based material or a titanium-based material and a tube material R made of stainless steel or a nickel-based alloy.
In order to use for dissimilar material joining, the inner layer material 11 is hollowed by through-holes.

The joining by the dissimilar material joint 14A constructed as described above is performed by connecting the above-mentioned pipe members Q and R to be joined to members made of the same kind of material as those, that is, the exposed side of the inner layer material 11 or the outer layer material 12. This is achieved by abutting the end and welding the entire circumference. In FIG. 6, a tube Q is welded to the exposed end of the inner layer 11 and a tube R is welded to the exposed end of the outer layer 12, respectively. This is because the inner layer 11 is made of the same material as the tube Q, that is, a zirconium-based material. Material or titanium-based material, and the outer layer material 12
Is made of the same kind of material as the tube material R, stainless steel or a nickel-based alloy, and vice versa.

Finally, the test results which are the criteria for each of the above-mentioned limiting conditions in the method of the present invention as described above will be described. In this test, an inner layer material 11 made of pure zirconium or Ti-5% Ta alloy and an outer layer material 12 made of SUS304L are used, and an intermediate layer 13 interposed therebetween is made of pure Ta having a thickness of 0.1 mm and a width of 100 mm. Using a foil, the cladding material 10 was constructed by changing the fitting conditions and the degree of vacuum inside at the time of manufacture in various ways, and further using this to perform rolling under various conditions to produce the clad material 14. And compare the joint state and corrosion resistance in each case.
It is what went .

Table 1 shows the chemical composition of pure zirconium and Ti-5% Ta alloy used as the inner layer material 11 and pure Ta used as the intermediate layer 13, and Table 2 shows the chemical composition of SUS304L used as the outer layer material 12. Show. The dimensions of the inner layer material 11 and the outer layer material 12 were three types shown in Table 3.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

The specifications of the inclined rolling mill for reducing the clad material 10 are as follows: the crossing angle γ is 3 °, the inclination angle β is 9 ° or
11 °, the roll diameter is 120 mmφ or 180 mmφ, the roll rotation speed is 50 rpm, and the roll of 180 mmφ corresponds to the clad material 10 corresponding to the reference numerals a and b in Table 3, while the roll of 120 mmφ corresponds to the reference numeral c. Each corresponding clad material 10 was used.

[Test 1] First, to examine the effect of the degree of vacuum inside the clad material 10 on the bonding strength at the bonding interface,
The cladding material 10 corresponding to the symbol B in Table 3 was prepared by setting the inner vacuum degree to 2 × 10 ⁻¹ Torr, 2 × 10 ⁻² Torr, 9 × 10 ⁻³ Torr, 1
Each of them was prepared by changing to five types of × 10 ⁻³ Torr and 2 × 10 ⁻⁴ Torr, and all of them were heated to 900 ° C. and then tilt-rolled to produce a clad material 14 having an outer diameter of 34 mm. At this time, the area reduction rate is approximately 28%, which satisfies the above-described limitation condition, and also satisfies the limitation condition for the clearance ratio C.

The five kinds of clad materials thus obtained
14 is cut to an appropriate length, and two shear test pieces 14a each made by removing the outer layer material 12 and the intermediate layer 13 on the other side while leaving a joint portion of a predetermined length h on one side are produced, The bonding strength of each of these was examined by a shear test performed in the manner shown in FIG.

In this shear test, a high-rigidity test block having a circular opening 15a slightly exceeding the outer diameter of the inner layer material 11 was used.
By using 15, the end surface of the shear test piece 14 a on the side where the outer layer material 12 remains is abutted on the opening 15 a concentrically, and the shear test piece 14 a
At the other end of the joint, a load P in the direction of pushing into the opening 15a is applied to break the joint, and the shear strength is determined from the load P at the time of fracture, the length h of the joint, and the diameter D of the joint by the following equation. I went according to the procedure. Shear strength = P / (π · D · h) (5)

FIG. 8 shows the test results. From this figure, it is clear that correlation between the cladding material 10 inside the vacuum and shear strength are present, to obtain a 20 kgf / mm ² or more shear strength required in the bonding interface, the cladding material The upper limit of the degree of vacuum at the manufacturing stage of 10 is 1 ×
Must be 10 ^-2 Torr.

It should be noted that the above-described criteria for determining the shear strength (20
kgf / mm ² ) is the shear strength (= 20 kgf / mm ² ) of stainless clad steel standardized to JISG3601 and JI
It can be said that it is appropriate compared to the shear strength (= 14 kgf / mm ² ) of titanium clad steel standardized in SG3603.

[Test 2] Further, in order to examine the effect of the clearance ratio C upon assembling the clad material 10, a plurality of clad materials 10 corresponding to the reference numerals a, b and c in Table 3 were used. Was heated to 900 ° C., then subjected to drawing rolling under various rolling conditions, and an ultrasonic flaw detection test was conducted over the entire length and the entire circumference of the obtained clad material 14 under the flaw detection conditions shown in Table 4. Then, the bonding state at the bonding interface was examined.

[0052]

[Table 4]

Each clad material 10 used in this test was
When assembling, the degree of vacuum inside was 2 × 10 ^-4 Torr
Is maintained in, and, prior to assembly of the clad material 10, the outer diameter d ₂ of the inner diameter d ₁ and the inner layer material 11 of the outer layer material in each measured using calipers, these measurements (2) Each clearance ratio C was accurately obtained by substituting into the equation. Further, the outer diameter of the clad material 10 before the reduction rolling and the outer diameter of the clad material 14 obtained after the reduction rolling are also measured, and these measured values are substituted into the equation (4) to obtain the respective rolling ratios A. Sought exactly.

FIG. 9 shows the test results. The horizontal axis in this figure is the rolling ratio A of the reduction rolling performed to obtain the clad material 14 from each clad material 10, and the vertical axis is each clad material.
The clearance ratio C is 10, and the circles in the figure indicate that a good bonding state is obtained over the entire surface, and the black circles indicate the case where an unbonded portion is formed.

From FIG. 9, it can be seen that a non-joined portion occurs under the condition that the clearance ratio C is large, and the limit value of the clearance ratio C at which the unjoined portion occurs increases as the rolling ratio A increases. Recognize. From FIG. 9, when a limit line at which an unjoined portion is generated is extracted, C = 1.2 × A + 0.92 (6), and the portion below this limit line in FIG. Clad material that meets the limited conditions shown
In the clad material 14 manufactured using No. 10, it was found that a good bonding state was obtained over the entire surface.

[Test 3] Table 3 was used to examine the effects of the reduction in area during drawing and the heating temperature prior to drawing on the bonding strength, corrosion resistance and roundness of the bonding interface.
After assembling a plurality of clad materials 10 corresponding to the code b and heating each of them to an appropriate temperature within a range of 750 ° C to 1100 ° C, an appropriate area reduction rate of 5% to 45% is obtained. Each of the obtained clad materials 14 was examined for shear strength, corrosion resistance, and roundness of the joint interface. In addition, assembling of each clad material 10, the inner vacuum degree is 1 ×
The ^measurement was performed at a clearance ratio C of 2.0 or less while maintaining the value at 10 ^-3 or less.

First, according to the test method shown in FIG.
FIG. 10 shows the result of comparing the shear strengths obtained by the equation (5). The horizontal axis in this figure is from each clad material 10 to clad material 14
The vertical axis represents the heating temperature of each clad material 10 before the reduction rolling, and the black circles in the figure indicate the above-described determination values of the shear strength (20 kgf / mm ² ).
What is less than, ○ mark, those that obtained a shear strength of 25 kgf / mm ² or more greatly exceeded the determination reference value,
△ mark represents respectively those 20kgf / mm ² ~25kgf / mm ² becomes shear strength was obtained.

From this figure, it can be seen that the heating temperature before the rolling was 800 ° C.
In the case of the above, it is clear that a shear strength of 20 kgf / mm ² or more can be stably obtained regardless of the reduction in area,
The lower limit of the heating temperature in the method of the present invention is set based on this result.

The corrosion resistance was compared by cutting each clad material 14 in a plane perpendicular to the axis, and dividing the clad material 14 in a plane including the axis, as shown in FIG. 3mm thick corrosion test piece 14b having a semicircular shape and a closed glass container having two upper and lower locking claws 21 and 22 inside
The test was carried out based on a corrosion test performed using a test apparatus shown in FIG. 12 including a heating device 20 and an electric heater 23 for heating.

In this corrosion test, as shown in FIG. 12, the corrosion test pieces 14b, 14b are locked to the upper and lower locking claws 21, 22, respectively, and the lower corrosion test piece 14b is fitted inside the glass container 20. Only after the corrosion liquid 24 is immersed in the corrosion liquid 24 and heated by the electric heater 23 to maintain the boiling point of the corrosion liquid 24 for 120 hours, the corrosion test piece 14b (liquid phase test piece) in the corrosion liquid 24 and The other corrosion test piece 14b (gas phase test piece) is taken out, and each of the test pieces 14b and 14b is cut in the radial direction as shown by the broken line in FIG. The procedure was performed to measure the maximum corrosion depth. Table 5 shows the composition of the etchant 24, and Table 6 shows a list of reagents for the added ions. Also corrosive liquid
The specific liquid volume of 24 was 20 ml / cm ² .

[0061]

[Table 5]

[0062]

[Table 6]

FIG. 13 shows the results of the above corrosion test.
The horizontal axis and the vertical axis of this drawing are the reduction ratio of the reduction rolling and the heating temperature before the reduction rolling, similarly to those in FIG. 10, and the circles in the figure indicate the results in the liquid phase test specimen in the lower half. The upper half shows the results of the gas phase test piece, and the black and white of both halves show the measured depth of corrosion as shown in the figure.

From this figure, it can be seen that the heating temperature before the rolling was 1000 ° C.
In the following cases, it is clear that corrosion of the bonding interface hardly occurs irrespective of the reduction in area, and the upper limit of the heating temperature in the method of the present invention is set based on this result.

For comparison with the above, the cladding material 10 having no intermediate layer 13 was formed under the conditions corresponding to the symbol B in Table 3, and the cladding material 10 was heated at a heating temperature of 900.
As a result of performing the above-described corrosion test on the clad material 14 manufactured under the condition of ℃ and a surface reduction rate of 30%, the corrosion depth at the joint interface was 360 μm for the liquid phase test piece and 1500 μm for the gas phase test piece. Also reached. From this, it became clear that the presence of the intermediate layer 13 made of tantalum is effective for improving the corrosion resistance.

For comparison of the roundness, the clad material 14 manufactured under the above-described conditions was cut along a plane perpendicular to the axis.
The outer diameter of the inner layer material 11 on this cut surface is measured at a plurality of locations in the circumferential direction, and the roundness of the inner layer material 11 in each clad material 14 is obtained by using the measured values according to the following formula, and the results are compared. The procedure was as follows.

FIG. 14 shows the result. From this figure, it can be seen that under the condition that the heating temperature before the reduction rolling is within the above-mentioned appropriate range (800 to 1000 ° C.), the area reduction exceeds 40% and the roundness is reduced. As described above, the dissimilar joint 14A obtained by the method of the present invention removes the outer layer material 12 and the intermediate layer 13 on one side of the clad material 14 to expose the inner layer material 11, and on the other side, the inner layer material 11 and the intermediate layer 11. The outer layer material 12 is exposed by removing the layer 13, and since the exposed end becomes a joining end with the pipe material Q or R, it is necessary to have an accurate circular cross section. That is, the inner layer material 11 at the stage of the clad material 14
Is important to ensure a circular shape at the joint end of the dissimilar joint 14A obtained as a product, and in order to obtain a good dissimilar joint 14A, the circularity must be 95% or more. It is desirable that the upper limit of the area reduction rate satisfying this condition is 40
%.

The shortage of the area reduction rate is caused by the inner layer material 11 and the outer layer material 12.
It is clear that this is directly related to the lack of joint strength at the joint surface with the steel, and only the area reduction rate is changed while all the other conditions described above are satisfied, and the criterion value for the shear strength (20 kgf / mm ² )
As a result of obtaining the lower limit of the area reduction rate on the condition that it exceeds the above, it was found that this lower limit was 5%.

The results of the above Test 3 are summarized in FIG.
It becomes as shown in. That is, the clad material 10
The area reduction rate of the reduction rolling performed to obtain 14 is 5% or more to secure the joining strength between the inner layer material 11 and the outer layer material 12, and 40% or less to ensure the roundness of the inner layer material 11. In addition, the heating temperature of the clad material 10 in the previous stage of the reduction rolling is set to 800 ° C. or more in order to secure the bonding strength between the inner layer material 11 and the outer layer material 12. It is necessary to keep the temperature at 1000 ° C. or lower in order to maintain good corrosion resistance at the bonding interface of the alloy.

[0070]

As described above in detail, in the method of the present invention, the conditions of the cylindrical outer layer material and the circular inner layer material are set so that the clearance ratio between the two satisfies the formula (2), The clad material is sealed by keeping the inside thereof at a vacuum of 1 × 10 ^-2 Torr or less to form a clad material.
℃, and the outer diameter of the inner layer material and the outer layer material are diffused well because the outer diameter material is rolled at an area reduction ratio of 5% to 40% by an inclined rolling mill equipped with three or more cone-type rolls. The present invention has an excellent effect, for example, it is possible to stably produce a dissimilar joint having excellent joining strength and corrosion resistance by joining with high productivity.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a clad material used in the method of the present invention.

FIG. 2 is a partially broken side view of a clad material used in the method of the present invention.

FIG. 3 is a schematic side view of a tilt rolling mill used for carrying out the method of the present invention.

FIG. 4 is a front view of a tilt rolling mill used for carrying out the method of the present invention.

FIG. 5 is a plan view of a tilt rolling mill used for carrying out the method of the present invention.

FIG. 6 is an explanatory view of a joined state by a dissimilar joint manufactured by the method of the present invention.

FIG. 7 is an explanatory diagram of a shear test performed for evaluating a bonding strength at a bonding interface.

FIG. 8 is a diagram showing the relationship between the bonding strength at the bonding interface of the clad material and the degree of vacuum inside the clad material.

FIG. 9 is a diagram showing the effect of the clearance ratio of the clad material and the reduction in area during reduction rolling on the quality of the bonding state of the clad material.

FIG. 10 is a diagram showing a relationship between a clearance ratio of a clad material, a reduction in area during reduction rolling, and a bonding strength at a bonding interface of the clad material.

FIG. 11 is a schematic diagram of a test piece used for a corrosion test for evaluating corrosion resistance of a bonding interface.

FIG. 12 is an explanatory diagram showing the state of execution of a corrosion test for evaluating corrosion resistance of a bonding interface.

FIG. 13 is a diagram showing the relationship between the reduction in area during reduction rolling, the heating temperature before reduction rolling, and the corrosion resistance of the bonding interface.

FIG. 14 is a diagram showing the relationship between the reduction in area at the time of reduction rolling, the heating temperature before reduction rolling, and the roundness of the inner layer material in the clad material.

FIG. 15 is a diagram showing an appropriate range of rolling conditions in reduction rolling performed to obtain a clad material from a clad material.

[Explanation of symbols]

 10 Clad material 11 Inner layer material 12 Outer layer material 13 Intermediate layer 14 Clad material 14A Dissimilar material joint 14a Shear test piece 14b Corrosion test piece

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuyuki Nakasuji 4-33, Kitahama, Chuo-ku, Osaka-shi, Osaka Prefecture Inside Sumitomo Metal Industries, Ltd. (72) Kazuhiro Ogawa 4-chome, Kitahama, Chuo-ku, Osaka-shi, Osaka No. 5-33, Sumitomo Metal Industries, Ltd. (72) Inventor Kazuo Fujisawa 4-33, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (56) References JP-A-64-71582 (JP, A) JP-A-63-36903 (JP, A) JP-A-2-169191 (JP, A) JP-A-2-134485 (JP, A)

Claims (1)

(57) [Claims] 1. A zirconium-based material or a titanium-based material
Material of circular section made of stainless steel or stainless steel
A cylindrical outer layer material made of a nickel-based alloy or stainless steel.
Inner layer of circular section made of stainless steel or nickel-based alloy
Material and zirconium-based or titanium-based material
A cylindrical outer layer material is fitted with an intermediate layer made of tantalum interposed therebetween to form a clad material, and the clad material is heated to a predetermined temperature and drawn by rolling the outer diameter to form a clad material. None, a method of manufacturing a dissimilar joint in which an outer layer material and an intermediate layer are removed at one end of the clad material and an inner layer material and an intermediate layer are removed at the other end, respectively, wherein the outer layer material and the inner layer material are fitted. Clearance ratio C between the two
With respect to the rolling ratio A during the reduction rolling, C ≦ 1.2 × A
+0.92 (%) and set the inside of these to 1 × 10
^-2 Torr or less and the hermeticity of the clad material is hermetically sealed, and the heating temperature before drawing is 800 ° C.
絞 り 1000 ° C., and the reduction rolling is performed by a tilt rolling mill having three or more cone-shaped rolls in a range of 5% to
A method for manufacturing dissimilar material joints, wherein the method is performed with a reduction in area of 40%.