JPS6152996A - Method of joining stainless steel to ti base or zr base metal - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and bending ductility at interface of joining by making alloy elements in stainless steel to solid solution in an insert material interposing specified insert material. CONSTITUTION:When making diffusion joining by hot hydrostatic pressure pressing method making Ti and Zr as the first member 1 and stainless steel as the second member 2, beta type Ti-base alloy or beta type Zr-base alloy is used as an insert material 3. This is interposed between the first member 1 and the second member 2, and hot hydrostatic pressure pressing method is performed by heating to a temperature below beta transformation point of the first member.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method of processing pure Ti, pure Zr, etc. (including non-β-type alloys) into stainless steel by hot isostatic pressing (hereinafter referred to as HIP method). The present invention relates to a joining method, and particularly relates to a solid phase joining method that can prevent a decrease in corrosion resistance at a joint portion and also prevent a decrease in fatigue strength.

[Conventional technology]

Ti and Zr (pure Ti unless otherwise specified.

Pure Zr or a non-β-type Ti-based or Zr-based alloy (the same shall apply hereinafter) is widely used as a metal with good nitric acid corrosion resistance. Stainless steel is also a valuable metal with similar properties. However, the chemical behavior towards nitric acid is not completely the same among these three metals, so it is necessary to use Ti (or Zr) and stainless steel properly in consideration of the usage environment. This sort of use is often done even within a single plant; if Ti or Zr is suitable under one environmental condition and stainless steel is suitable under another, then the Uses strong metal materials. Therefore, it is necessary to join dissimilar materials at these interfaces, but depending on the field of application, you may have to hesitate to use a 7-lunge joint, which has low reliability in terms of sealing performance. In such cases, it is common to consider metal-bonded joints, but as is well known, Ti and Zr cannot be welded or fusion-welded with stainless steel, so it is inevitable to try to obtain metal-bonded joints. In this case, the surface to be drawn must rely on the HIP method described above. and Korote Ti
Although it has been confirmed that it is technically possible to diffusion bond +Zr with stainless steel by the HIP method, it is also known that the physical properties of the bonded portion are adversely affected. That is, at the diffusion bonding interface of the metals, one component, Tf or Zr, and the other component, Fe+Cr+
Ni gathers and intermetallic compounds (e.g. Ti
Fe, ZrFe, etc.) are formed, which reduces the nitric acid corrosion resistance and ductility (bendability) at the interface, making it unsuitable for practical use.

Also, if we consider the case where a heat medium comes into contact with such a joint discontinuously, thermal stress will be repeatedly applied to the joint of dissimilar metals with different Young's moduli and coefficients of thermal expansion). There is a problem that thermal fatigue strength becomes poor.

[Problem that the invention seeks to solve]

After all, when joining stainless steel to Ti+Zr using the HIP method, there is a problem of a decrease in nitric acid corrosion resistance or a decrease in ductility due to the formation of intermetallic compounds as described above, and depending on the application. The problem is a decrease in thermal fatigue strength due to thermal stress. Therefore, in order to make the joining of Ti (or Zr) and stainless steel by the HIP method practically possible, it is important to prevent the deterioration of the nitric acid corrosion resistance, especially at the joining interface. The next important issue is to make structural improvements that can improve thermal fatigue strength.

[Means for solving problems]

The key point of the present invention that is effective in improving nitric acid corrosion resistance is that Ti+Z
R is the first member, stainless steel is the second member, and both are H.
The force described for diffusion bonding by the IP method, a β-type Ti-based alloy or a β-type Zr-based alloy as an insert material, is interposed between the first member and the second member, and the temperature is below the β-transformation point of the M1 member. The point is that the HIP method is performed by heating to . Note that when the HIP method is employed, the cooling rate within the apparatus is necessarily slow, and the gold dust structure at the joint tends to undergo some unfavorable changes during the slow cooling process. Therefore, the gist of the present invention also lies in the fact that the bonded product taken out from the device is heated to a temperature higher than the β-transformation point of the insert material and lower than the β-transformation point of the first member, and then further rapidly cooled. do.

Next, regarding the improvement of thermal fatigue strength due to cyclic thermal stress,
The joint between the second member and the insert material is made so that the former is a female type and the latter is a male type (this male type is at least upright on the root side) with an angle of 1
The object is achieved by providing a male and female fitting structure in which the angle is 0 to 60 degrees, and this point also lies in the gist of the present invention.

[Effect]

Ti and Z for piping in fields where nitric acid corrosion resistance is required.
As r, pure Ti or pure Zr is generally used. Pure T
Since the metal structure of i and pure Zr is α phase (close-packed hexagonal crystal), the above α-
It is difficult to form a solid solution in TI or α-Zr. Therefore, it has been found that an intermetallic compound containing Ti (or Zr) as one component precipitates at the joint interface, which reduces the nitric acid corrosion resistance as described above and also has an adverse effect on ductility.

Based on these considerations, we found that α-Ti and α-Zr (not limited to pure Ti and pure Zr, but all that form an α phase even if they are Ti-based alloys or Zr-based alloys are included here) ) has come to be recognized that directly bringing stainless steel into close contact with the steel is the root cause of the above-mentioned problems. Therefore, we obtained a guideline that a metal that has good nitric acid corrosion resistance and does not cause the precipitation of intermetallic compounds should be interposed between the two as an insert material, and we conducted research based on this guideline. As a result, in the case of β-phase (body-centered cubic) Ti-based alloys and Zr-based alloys, it is possible to incorporate far more dissimilar elements such as FC, Cr, and Ni into solid solution than in the α-phase. I focused on it. That is, a β-type Ti alloy or a β-type Zr alloy is interposed between the first member and the second member as an insert material, and HI
When P treatment is performed, both the insert material and the first member are made of Ti.

Or, because Zr is used as a matrix, it is possible to obtain intermetallic bonding with perfect affinity and extremely good integrity, and for joining the insert material and the second member, Fe s Cr t N in the second member is etc. are dissolved in the β phase of the insert material, so precipitation of intermetallic compounds can be largely avoided. Therefore, problems with nitric acid corrosion resistance, ductility, etc. are less likely to occur not only at the bonding interface between the first member and the insert material, but also at the bonding interface between the insert material and the second member.

Next, it has been found that there are the following problems associated with HIP processing due to limitations on the equipment. That is, when a HIP device is used, the cooling process after completion of metal bonding by pressure heating is carried out in a HIP furnace, and therefore must be gradually cooled. However, it is known that when β-type Ti-based alloys and β-type Zr-based alloys undergo a slow cooling process, they form a two-phase structure (α+β) at room temperature. Some precipitation of intermediate compounds can be seen. Therefore, after metal joining by the HIP method is completed, if a post-heat treatment is performed to stabilize the β phase by reheating the joint to a temperature above the β transformation point of the insert material and then rapidly cooling it, the insert material and The intermetallic compounds that had been precipitated between the second members are also dissolved into the β-phase insert material, and the nitric acid corrosion resistance and ductility of the joint are significantly improved.

The heating temperature during HIP processing in the present invention must be a temperature that allows thermal diffusion bonding, and is generally 700°C.
However, the upper limit of the heating temperature and the heating temperature in the post-heat treatment for stabilizing the β phase are as follows:
It should be below the β transformation point of the member. This is to avoid a situation where the base material Ti or Zr turns into an α phase when cooled, resulting in a decrease in ductility.

Note that the β-type Ti-based alloy and β-type Zr-based alloy used as insert materials refer to the following metallization. First, β-type Ti-based alloy is M o HV r N b +Ta,
A Ti-based alloy containing at least 1 m selected from the group consisting of W and Mn in the following ranges (all weight ratios): 5 CH≦MO≦30% 5≦V 550% 10 CH≦Nb≦ 40 lines 15 cracks ≦ Ta ≦ 30% 5% ≦ W ≦ 15 pieces 5 pieces ≦ Mn ≦ 20 pieces If two or more alloying elements from the above are to be blended, the lower limit of the total blended amount at that time considers the lower limit amount given for the alloying element with the highest lower limit value among the alloying elements blended as the total lower limit value (however, for individual alloy elements, even if the amount falls below the individual lower limit value, On the other hand, the upper limit of the total amount of blended alloying elements is considered to be the upper limit given for the alloying element with the highest upper limit (however, for individual alloying elements, the upper limit of each ). Examples of such combinations of two or more alloying elements are 1 (1≦Mo+Nb≦40chi (however, Mo is 30chi or less), 15%≦Mo+Nb+Ta≦40% (however, Mo and Ta are 3 o attack or less).

Next, a β-type Zr-based alloy is a Zr-based alloy containing Nb or Ta in the following ranges: 8 ≦ Nb ≦ 60 5 Chi ≦ Ta ≦ 50 , 8chi≦Nb+Ta≦ according to the same concept as in the case of the βTi-based alloy described above.
60 rice cakes (however, Ta is less than 50q6).

The reason for specifying the above-mentioned alloying elements in the β-type Ti-based alloy and β-type Zr-based alloy is that they are β-phase stabilizing elements of Ti and Zr, and are solid solution type (non-intermetallic compound forming type). ). Mn mixed with Ti is of the eutectoid type (intermetallic compound forming type) and does not seem to meet the above conditions, but since the eutectoid reaction progresses extremely slowly, there is no practical problem in mixing it. Included in possible elements.

5. The above-mentioned preferred ranges for the individual and total amounts of these alloying elements are defined for the following reasons. In other words, the elements MotV, Nb, Ta, and W should be used to the extent that the melting point does not become abnormally high when used as an insert material, in other words, the lower limit temperature of the diffusion bonding chamber does not become abnormally high, and therefore the β transformation of the first member is maintained. H at temperatures below the point
The upper limits for each were determined in consideration of the limits that would allow IP treatment, and the upper limits for Mn were determined in consideration of the limits that would prevent intermetallic compounds from appearing in the β phase during the HIP treatment. . On the other hand, the lower limit is set for the following reasons common to each element: (1) a sufficient amount of β phase is expressed at the HIP treatment temperature; (3) By heat treatment after HIP (i.e., β phase, rapid cooling treatment for stabilization), β
This is determined based on the following reasons: that a phase-rich structure can be formed.

The insert member of the present invention has the above β in Ti and Zr.
Although it contains phase stabilizing elements, if the above conditions are satisfied, it can contain other alloying elements such as eutectoid β-stabilized, α-stabilized, neutral type, etc. Among these, eutectoid type As a β stabilizing element for Ti, F e p Cr *
Examples include N s HCo HCu rAg, St, H, Pd, etc., and those for Zr include Fe, CrtNi
tMo, V, W.

Examples include H*CoyMntCu*Ti+Ag, etc., and the casting elements in the text include Zr and S as opposed to Ti.
Examples include n and the like, but these are blended within a range that does not have a significant adverse effect on the melting point. Examples of α stabilizing elements include AI, C, 0, N, etc. for Ti, and AI+5ntBet for Zr.
Examples include Pb, N, 0+Hf, etc., but these may be used to the extent that they do not impair the β-phase stabilizing function of the β-phase stabilizing element (
As a guideline, it is permissible to mix up to about 25% of the total amount of β-phase stabilizing elements (including blending as impurity elements). And to show a particularly typical example of composite formulation, T i-15M
o-5Z r-(3A 1 ), T i -11V
11Zr-2AI-2Sn, Ti-8Ti-8V4
Cr-4Z r-3A I, T 1-8M.

sv 2Fe 3AI, Ti 13V 11Cr
-3AI, Ti-11,5Mo-62r 4.55n
etc.

On the other hand, from the gist and structure of the present invention, β-type Ti-based alloys and β-type Zr-based alloys are naturally excluded from application to the first member, but conversely, pure Ti and pure Zr
The first member of the present invention includes not only Ti-based alloys but also all Ti-based alloys and Zr-based alloys. Such alloys are α-type alloys and (α+β)
Typical examples are pure Ti, Ti-
0.2Pd.

T 1-5Ta, T i-0,3Mo-0,8N
i, Ti-6A1-4V, Ti-5Al 2.5
Sn, Ti-8ATi-8A1-I, TI 6A1
2Sn-4Z r-6Mo, T 1-3A 1-2
．． 5V, Ti-5AI-2Cr-IFe, pure Zr, Zircaloy-2, Zircaloy-4[:Zn-1,
53n (Fe+Cr+Ni) system), Z r-2
, 5Nb, etc.

Next, there is the issue of thermal fatigue strength due to repeated thermal stress.Even if an insert material like the one mentioned above is used, HIP treatment by simply butting together planes will not provide highly reliable thermal fatigue strength. I can't get it. For this reason, for example, when the object to be joined is a pipe body, the reliability as a practical pipe joint has to be low in fields where a heat medium passes discontinuously within the pipe.

After examining the background of such problems, it was found that the first member and the second member have different Young's modulus and coefficient of thermal expansion. Since this situation does not substantially change even when an insert material is inserted, it was determined that structural improvements to the abutting surfaces were necessary.

Therefore, we decided to conduct a basic experiment first, using industrially pure Ti (
JIS standard type 2), industrial pure Zr (ASTM702
) and S.U.S. 304 stainless steel
50mmφX50m+nA? A round bar test piece was prepared.

Then, the flat end surfaces of the round bars were butted together using a combination of Ti/5US304 and Zr/5US304, and steel pipes (sTP
G38) Enclose in an i-capsule and vacuum the inside of the capsule (1
0-3 Torr), then 850 Y'
HIP treatment was performed at CX100O atmosphere for 1 hour to diffusion bond the round bars. The capsule was removed and machined to an outer diameter of 42mmφ and an inner diameter of 32mmφ (wall thickness 5mmt).
, length 80MA! A tubular joint material was obtained.

The shape of the joint surface at this time was as shown in FIG. 5, and the joint end surface of the tube was at 90 degrees with respect to the tube axis. When several such test specimens were made and one of them was subjected to an axial tensile test, it was 28 kg/7 + Z for Ti/SUS 304.
For r/SUS 304, the pressure was 26 kg/mf, and it was confirmed that the bonding strength of the adhesion part itself was sufficient. Next, the test piece was cut in half in the axial direction and a dye penetrant inspection was performed on the inner and outer surfaces of the tube, and it was confirmed that there were no cracks at the joint interface, and an X-ray transmission inspection revealed internal defects at the joint interface. I couldn't do that. After confirming these points, a thermal fatigue test was conducted using a fluidized bath type thermal fatigue tester as shown in FIG. 1 (schematic diagram). That is, a heating tank 6 that maintains ion-exchanged water 4 in a boiling state by a heater 5, and a refrigerant circulation system 7. Pump 8. A cooling tank 10 equipped with a heat exchanger 9 and maintaining ion-exchanged water 11 at room temperature is installed in parallel,
The test piece 12 is moved up and down (arrow Y direction) and horizontally (arrow
Direction) A specimen holding and moving device 13 for freely holding the specimen is provided above them. Then, the test piece 12 was repeatedly subjected to a thermal history consisting of one cycle of boiling ion-exchanged water 4 (10 seconds), moving cooling (5 seconds), and room temperature ion-exchanged water 11 (10 seconds).

The test was interrupted every 100 cycles, and the bonding interface (inner and outer surfaces of the tube) of the test piece was visually observed and subjected to a dye penetration test to investigate the occurrence of cracks. The total number of cycles up to the time when cracking was observed was defined as the thermal fatigue life.

According to this, with the joint surface shape as shown in Fig. 5, Ti/5
600 cycles for US304, and Zr/5US3
In the case of No. 04, cracks were observed on the outer surface of the tube after 400 cycles, confirming that the thermal fatigue life was short.

Through these basic experiments, it was confirmed that the difference in material between the first member and the second member (difference in Young's modulus and coefficient of thermal expansion) was the cause of crack occurrence. And considering the case of inserting the insert material as mentioned above,
The matrix metal of both the first member and the insert material is Ti or Zr, and because they are common in material, there is no substantial difference in physical properties, and the joint surface may be simply a work surface joint. However, since there is already a difference in physical properties between the insert material and the second member due to the difference in the simatrix metals, it was thought that it was necessary to devise some kind of ingenuity regarding the joint surface structure.

Therefore, we investigated metal bonding structures to increase thermal fatigue strength. That is, as shown in Fig. 2, a Taber joint surface having a contact angle of θ is formed between the insert material 3 and the second member 2, and 01 is varied between -70° and 70° to determine the thermal fatigue life. I considered whether it would change. The reason why 01 is a negative angle is because the insert material 3 is connected to the second member 2 as shown by the broken line.
This shows that the taper junction is in the direction of covering the area. In conclusion, we have found that when θ is set in the range of 10' to 60°, the thermal fatigue life is significantly improved. In particular, in the range of θ = 10' to 4.5°, no cracks were observed on the outer surface of the pipe where the tapered surface was joined, and only cracks were observed on the inner surface of the pipe where the vertical surface was joined. do not have. By making the outer surface of the tube a tapered surface joint, cracks on the inner surface of the tube can be suppressed even if the inner surface of the tube is a vertical surface joint. Although a significant improvement effect was obtained compared to the example, in order to obtain an even safer practical piping joint, the joint between the insert material 3 and the second member 2 was changed as shown in Fig. 1. Thermal fatigue life was measured by making tapered surface joints on both the inside and outside of the pipe, setting 01 to the appropriate angle determined above, and keeping only the angle θ2 on the inner surface of the pipe unchanged between -70° and 70°. did. As a result, by setting θ2 within the range of 10° to 60°, especially 30° to 45°, the risk of siflux occurrence was further reduced significantly.

As a result of the above consideration, the joint between the insert material 3 and the second member 2 is designed to have a male-female fitting structure in which the latter covers the former as well as the inner and outer surfaces, and the angle of 10°≦01. It was concluded that if the condition θ2≦60° is satisfied, a metal joint can be obtained that has no disadvantages at all as a practical joint. Same as above. The male-female mating state that satisfies the condition of gold is to be established between the insert material and the second member, but for this purpose, various forms of the insert material 2 as illustrated in Fig. 3 are required. It is desirable to give In FIG. 3, the first member 1 and the second member 2 to be joined are shown facing each other. Figure 3 (5
) is trapezoidal, (B) is triangular, and (C) is a trapezoid with a wavy upper base, and the joint side with the first member (left side in the figure) is a vertical surface. E) , (E)
Then, for the joining side as well, let's assume a male and female mating structure (D
) is a case where the first member 1 is a male type, and (E) is a case where the first member 1 is a female type. Regarding the axial length of the insert material 3, it is sufficient to have a length that prevents the constituent elements of the M2 member 2 from diffusing to the first member 1. ~1500 atm, 0.
5 to 2 hours), but it is recommended that it be 0.5 mm or more.

Furthermore, the field of application of the present invention is not limited to pipe materials, but can also be applied to plates and bars.

〔Example〕

Example 1 Following the basic experiment described above, the following experiment was conducted.

20 for industrial pure Ti+MZr and 5US304 steel
Prepare a round bar test piece of mmφx70mm', and
The end surfaces of the test pieces were butted against each other using a combination of S304 and Zr/5US304, and the test pieces were sealed in a steel pipe capsule. After evacuating the inside of the capsule, 800℃ x 100O atmosphere x 1
HIP processing was performed under the condition of time. Surface line Ti/5US
For the combination of 304, insert materials were directly butted together, and disk-shaped insert materials (20 mmφ x 1 mmE) made using various alloys shown in Table 1 were made using pure T
The one inserted between i and 5US304 was manufactured. Regarding the combination of pure Zr/5US304, there is one that is directly butted without an insert material, and one that is made of a disc-shaped insert material made using each moderate alloy shown in Table 1 (same dimensions as above).
were inserted in the same way. After the HIP treatment, the capsule was removed and the adhesion bond strength (uniaxial tensile) and bending ductility of the bond interface (JIS Z2248. bending R = 28 mn +
), a corrosion test was conducted in boiling f1148% nitric acid, and the depth of corrosion at the joint interface was measured by observation. The results are also listed in Table 1.

In Table 1, 11kLl, 51, which did not include an insert material, gave particularly poor results in terms of bending angle at break and depth of liquid interface erosion, and also did not have sufficient adhesion strength. Other experiments involved using insert materials, but those with “Example” written in the notes column are β
The insert material was a 凰Ti-based alloy or a β-type Zr-based alloy, and showed good results in each item. In addition, those described as comparative examples are those using insert materials that do not satisfy the above conditions.Those with a small amount of β-phase stabilizing elements have poor fracture bending strength and corrosion resistance, while those with a large amount of β-phase stabilizing elements have poor bending strength and corrosion resistance. In some cases, too much material made it impossible to join.

Example 2 f (insert material β→(α+β) by slow cooling after IP treatment
) Experiments were conducted on a method to improve the transformation by subsequent β-phase stabilization heat treatment by reheating and rapid cooling.

Regarding test pieces that were HIP-treated at 800°C, the HIF-treated one (comparative example) and the HIP-treated test piece were placed in an electric furnace and reheated [near the β-transformation point of the insert material (example) and beyond that]. After heating to a low temperature (comparative example) and immediately water quenching, test pieces were removed from the capsules and evaluated in the same manner as in Example 1. The results are shown in Table 2.

As shown in Table 2, after HIP treatment, the β
The material that was reheated to the transformation point and then rapidly cooled to stabilize the β phase was able to further improve the corrosion resistance and bending ductility of the joint interface compared to the material that had been subjected to HIP treatment or the material that had been heated at a lower temperature. .

Example 3 A tubular bonded test piece was prepared according to the procedure of the basic experiment described above. The shape of the joint surface is the same as shown in FIG. This was also subjected to a thermal fatigue test according to the basic experiment procedure. The results are shown in Table 3. In Table 3, * indicates that cracks occurred on the outer surface of the tube, and ** indicates that cracks occurred on the inner surface of the tube (no cracks occurred on the outer surface).

In addition, a negative value of 01 in Table 3 indicates that the bonded surface is in the state shown by the broken line in FIG.

The insert material used in this experiment was pure Ti/SUS 3
Ti-15V for 04 series, pure Zr/5US304
The system was made of Zr-15Nb, and the axial length was lrnm. Regarding heat treatment after HIP treatment, the former is SO
0°C x 30 mm + W, θ, the latter is 780°C x 3
0 m-+W, Q.

As shown in Table 3, the second member 2 covers the insert material 3 with male and female fittings, especially those with o2 of 10° to 60°.
The thermal fatigue life is greatly improved at 10°, especially at 10°.
In the case where the temperature was set to ~45'', no cracks occurred on the outer surface of the tube after 2700 to 2800 cycles, and it was expected that the thermal fatigue life of the male and female fitting portions would be even better.

Example 4 In response to the above results, a metal joint having a joint surface as shown in FIG. 1 was prepared and a thermal fatigue test was conducted for the purpose of improving the thermal fatigue life of both the inner and outer surfaces of the pipe. In Table 1 showing the results, the meanings of nine * marks and θ2=minus value are the same as in Example 3.

Table 4 As seen in Table 1, thermal fatigue life is significantly improved by setting θ2 to 10° to 60°, especially when θ2 is 20° to 45°.
℃, no cracks were observed even after 10,000 cycles.

〔Effect of the invention〕

By interposing the insert material, the alloying elements in the stainless steel could be made into a solid solution in the insert material, so the corrosion resistance and bending ductility at the joint interface were improved. Furthermore, by adding heat treatment for stabilizing the β phase, the above effect became even more stable.

Furthermore, by making the joint surface structure between the insert material and the stainless steel into a female-male fitting structure with the former having a convex shape, it was possible to significantly improve the thermal fatigue strength.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a male-female fitting structure using the insert material of the present invention, Figure 2 is a cross-sectional view of a tapered joint only on the outer surface of the tube, and Figure 3 is a cross-sectional view of the insert material of the present invention. 1 is an explanatory diagram of a thermal fatigue test apparatus, and FIG. 5 is a sectional view of a vertical surface joint.

Claims (4)

[Claims] (1) A Ti-based or Zr-based metal (excluding β-type Ti-based alloys and β-type Zr-based alloys) is used as the first member, stainless steel is used as the second member, and both are bonded by hot isostatic pressing. For diffusion bonding, a β-type Ti-based alloy or a β-type Zr-based alloy is used as an insert material, this insert material is interposed between the first member and the second member, and heated to a temperature below the β-transformation point of the first member. T characterized by performing diffusion bonding by
A method for joining stainless steel to i-based or Zr-based metals. (2) A Ti-based or Zr-based metal (excluding β-type Ti-based alloys and β-type Zr-based alloys) is used as the first member, stainless steel is used as the second member, and both are heated using hot isostatic pressing. For diffusion bonding, a β-type Ti-based alloy or a β-type Zr-based alloy is used as an insert material, this insert material is interposed between the first member and the second member, and heated to a temperature below the β-transformation point of the first member. After diffusion bonding, the β of the insert material
A method for joining stainless steel to a Ti-based or Zr-based metal, the method comprising heating to a temperature above the transformation point and below the β-transformation point of the first member, and then rapidly cooling. (3) A Ti-based or Zr-based metal (excluding β-type Ti-based alloys and β-type Zr-based alloys) is used as the first member, stainless steel is used as the second member, and both are bonded by hot isostatic pressing. In performing diffusion bonding, a β-type Ti-based alloy or a β-type Zr-based alloy is used as an insert material, and this insert material is interposed between the first member and the second member, and the joint between the second member and the insert material is The former is a female type and the latter is a male type with a rising angle of 10 to 60 degrees at least on the root side, and has a female-male fitting structure, and is characterized by performing diffusion bonding by heating to a temperature below the β transformation point of the first member. A method for joining stainless steel to a Ti-based or Zr-based metal. (4) Ti-based or Zr-based metal (excluding β-type Ti-based alloys and β-type Zr-based alloys) is used as the first member, stainless steel is used as the second member, and both are heated using hot isostatic pressing. In performing diffusion bonding, a β-type Ti-based alloy or a β-type Zr-based alloy is used as an insert material, and this insert material is interposed between the first member and the second member, and the joint between the second member and the insert material is The former is a female type and the latter is a male type with a rising angle of 10 to 60 degrees at least on the root side, which is a female-male mating structure, and after diffusion bonding is performed by heating to a temperature below the β transformation point of the first member. A method for joining stainless steel to a Ti-based or Zr-based metal, which comprises heating to a temperature above the β-transformation point of the insert material and below the β-transformation point of the first member, and then rapidly cooling.