JP6300323B2 - BONDED BODY, STRUCTURE, BONDED BODY MANUFACTURING DEVICE, AND BONDED BODY MANUFACTURING METHOD - Google Patents

Description

  The present invention relates to a joined body, a structure, a joined body manufacturing apparatus, and a joined body manufacturing method in which a brittle material and a steel-based material are diffusion bonded using an intermediate material.

  Conventionally, Patent Documents 1 to 3 have been proposed as techniques for relieving the thermal stress of a material having a large thermal expansion coefficient when different materials have different thermal expansion coefficients.

  In Patent Document 1, a superplastic alloy (for example, a Zn-Al alloy) is used as a connection material (solder) in order to relieve stress generated due to a difference in thermal expansion between a semiconductor element and a frame. Yes.

  In Patent Document 2, when manufacturing SiC fiber reinforced TiAl composite material, a large number of SiC fiber layers are sandwiched between TiAl base alloy foils having superplastic characteristics, and pressed under a predetermined condition to form a TiAl base alloy foil. And TiAl-based alloy foils are diffusion-bonded to each other.

Patent Document 3 proposes a thin-film magnetic head in which a superplastic alloy film is used as a stress absorber that absorbs the stress generated between the inorganic insulator and the magnetic body when both of them have a coefficient of thermal expansion.
Patent Documents 1 to 3 use a superplastic metal (or superplastic alloy) as a “brazing material”.

  Patent Documents 4 to 6 propose that after carbon steels are welded together or after carbon steels and low alloy steels are welded, they are allowed to cool or slowly cool and then heat-treated. After this heat treatment, residual stress is eliminated and cracks are prevented from occurring.

JP 2013-146664 A Japanese Patent Laid-Open No. 9-41053 Japanese Patent Laid-Open No. 11-306510 JP 2005-48271 A JP 2002-327214 A JP-A-6-330176

  In Patent Documents 1 to 3, superplastic metal is used as a “brazing material” having wettability for different materials having different coefficients of thermal expansion, and this is used as an intermediate material inserted between the different materials. . A diffusion reaction is promoted between the heated brazing material and the metal interface to form a bond, and during the subsequent cooling, the “brazing material” yields to relieve thermal stress.

  By the way, in the “brazing material”, a high-concentration intermediate material component is distributed at the joining interface of the base material. In this case, a compound of a base material and a component diffused from the intermediate material may be formed, and there is a concern about the embrittlement of the base material due to this compound.

  An object of the present invention is to solve the above-described problems, and there is no risk of embrittlement of the base material. By removing the thermal stress generated in the cooling process after bonding, the bonding strength is improved. An object of the present invention is to provide a bonded body and a structure that can be improved.

  Moreover, the other object of this invention is to provide the manufacturing apparatus which can obtain the said conjugate | zygote, and the manufacturing method of a conjugate | zygote.

In order to solve the above problems, the joined body of the present invention includes a brittle material having a low coefficient of thermal expansion and a steel-based material having a large coefficient of thermal expansion. Ri Na transformation superplastic material consisting of carbon steel between the steel-based material is inserted as an intermediate material, a layer made of the brittle material is a heat-receiving portion for receiving the heat input, the layer made of the steel material A gradually heating part that gradually heats the heat from the heat receiving part, and a heating medium passing part through which a heating medium passes is provided in the gradually heating part, and heat from the gradually heating part is transferred to the heating medium passing part. The flowing heat medium further gradually heats .

  The joined body manufacturing apparatus of the present invention includes a brittle material having a small thermal expansion coefficient and a steel-based material having a large thermal expansion coefficient, and is a joined body manufacturing apparatus in which both are diffusion bonded, wherein the brittle material In a state where a transformation superplastic material made of carbon steel is disposed as an intermediate material between the steel material and the steel material, a compressive stress applying portion that applies a compressive pressure to the brittle material and the steel material, A heating unit for heating the brittle material and the steel-based material, and heating control of the heating unit to heat up to a diffusion bonding temperature of the brittle material and the steel-based material, and during the heating, the compressive stress applying unit is Displacement is controlled so that only the intermediate material is deformed to join the brittle material and the steel-based material, and then cooling is performed by cycle processing or slow cooling processing in the phase transformation temperature range of the intermediate material. And a control unit.

The method for manufacturing a joined body of the present invention includes a brittle material having a low coefficient of thermal expansion and a steel material having a large coefficient of thermal expansion, and is a method for manufacturing a joined body in which both are joined by diffusion bonding. between the material and the steel material, and inserting the transformation superplastic material consisting of carbon steel as the intermediate member, the method comprising: diffusing junction of said brittle material and the steel material, after the diffusion bonding, look including the the steps of relaxing the residual thermal stress of the brittle material, said step of diffusion bonding is carried out at a temperature above the phase transformation temperature range of the intermediate member, the step of relaxing the residual thermal stress of the brittle material After the diffusion bonding is performed at a temperature exceeding the phase transformation temperature range, heat between the brittle material and the steel-based material due to phase transformation induced creep deformation by post-heat treatment in the phase transformation temperature range of the intermediate material. It relieves stress .

  The post heat treatment is preferably a cycle treatment or a slow cooling treatment in a phase transformation temperature range of the intermediate material.

According to the joined body and structure of the present invention, there is no risk of embrittlement of the base material, and the effect of improving the joint strength can be achieved by removing the thermal stress generated in the cooling process after joining. Play.
In addition, according to the manufacturing apparatus and the manufacturing method of the present invention, there is no possibility of embrittlement of the base material, and it is possible to improve the bonding strength by removing the thermal stress generated in the cooling process after the bonding. There exists an effect which can obtain a zygote suitably.

Sectional drawing of the conjugate | zygote of one Embodiment. Schematic of the manufacturing apparatus of a joined body. Explanatory drawing which shows each temperature change of a diffusion joining, cooling, and post-heat processing in a manufacturing method. The perspective view which shows the shape of the test piece of a conjugate | zygote. The simulation figure of a micro 4 point bending strength test apparatus. (A) is a graph showing the magnitude of the fracture stress by the micro bending strength test of Example 1, (b) is a graph showing the magnitude of the fracture stress by the micro bending strength test of Example 2, and (c) is the example. 3 is a graph showing the magnitude of the fracture stress by the micro bending strength test of No. 3, and (d) is a graph showing the magnitude of the fracture stress by the micro bending strength test of Example 4. FIG. The characteristic view which shows the relationship between the accumulation time of (gamma) / (alpha) transformation, and bond strength. Explanatory drawing of the test piece of the tension test of an intermediate material. The graph of the yield stress at the time of using the pure iron which is a comparative example when using S50C steel for an intermediate material. The schematic diagram which shows the example of a structure. The schematic diagram which shows the example of a structure. The schematic diagram which shows the example of a structure. The binary system equilibrium state diagram of Fe-C.

(First embodiment)
Hereinafter, a bonded body 10 according to an embodiment of the present invention will be described.
As shown in FIG. 1, the joined body 10 includes a brittle material layer 20, a steel-based material layer 30, and a transformation superplastic material layer 40 made of carbon steel as an intermediate material inserted therebetween.

  The bonded body 10 has an atomic interdiffusion when the brittle material layer 20 and the steel-based material layer 30 are heated (heated) to a diffusion bonding temperature that exceeds the phase transformation temperature range of the transformation superplastic material layer 40. Then, diffusion bonding is performed, and thereafter, the thermal stress generated with cooling is relaxed by the transformed superplastic material layer 40 by post-heat treatment. A specific method of the post heat treatment will be described in the manufacturing method described later.

(Brittle material)
Examples of the brittle material that forms the brittle material layer 20 include brittle metals such as tungsten W and molybdenum Mo, and ceramics centered on silicon carbide.

Here, as a representative example of the thermal expansion coefficient of these brittle materials, the thermal expansion coefficient of tungsten W is 4.5 × 10 ⁻⁶ / K at 25 ° C.
Molybdenum Mo has a thermal expansion coefficient of 4.8 × 10 ⁻⁶ / K at 25 ° C.

The thermal expansion coefficient of silicon carbide SiC is 6.6 × 10 ⁻⁶ / K at room temperature.
When the joined body 10 is configured, a layer made of a brittle material may be used as the heat receiving portion.
In this case, tungsten W as a brittle material has the highest melting point (3422 ° C.) among metals and can be widely used for ultra-high temperature applications. Tungsten W is suitable because it has a lower coefficient of thermal expansion than steel-based materials described later, and has extremely high shape stability at ultra-high temperatures. Molybdenum Mo has a melting point of 2623 ° C. and a stable crystal structure at normal temperature and pressure.

Silicon carbide SiC has a melting point of 2730 ° C. and is excellent in hardness, heat resistance, and chemical stability.
These brittle materials have high temperature resistance as the surface material of the blanket of the fusion reactor and are suitable.

(Steel material)
The steel-based material forming the steel-based material layer 30 typically includes oxide dispersion strengthened steel (ODS steel), F82H steel which is a low activation steel material, and the like.

When the joined body 10 is configured, if the layer made of the steel-based material layer 30 is a gradually heating portion that gradually heats the heat from the heat receiving portion, the heat from the brittle material layer 20 can be gradually heated.
ODS steels, for example, ODS steel basic composition having a Fe-15Cr-2W-0.2Ti- 0.35Y 2 O 3, 9Cr-ODS, the 12Cr-ODS or the like.

The composition of the 9Cr-ODS was C-0.14Si-0.06Mn-0.09P- <0.005, S-0.004Ni-0.03Cr-9.08W-1.97Ti-0.23Y-0. a _{.29O-0.16N-0.013Ar-0.0052Y 2} O 3 -0.37Ex.O-0.082.

The composition of the 12Cr-ODS is C-0.035Si-0.03Mn-0.02P- <0.005, S-0.003Ni-0.04Cr-11.65W-1.90Ti-0.29Y. a _{-0.18O-0.083N-0.005Ar-0.0052Y 2} O 3 -0.23Ex.O-0.03.

  The basic composition of F82H steel is Fe-8Cr-2W-0.2V-0.04Ta-0.1C, which is a low activation ferritic steel. In addition to this, the low activation ferritic steel as the steel material includes, in addition, EUROFER-EU (basic composition is Fe-9Cr-1.1W-0.11C-0.2V- (0.06-0.09). ) And CLAM (basic composition is Fe-9Cr-1.55W-0.2V-0.15Ta-0.11C), etc., and these may be employed. The numerical value of the composition is% by weight (hereinafter the same).

Steel-based materials have a larger coefficient of thermal expansion than the brittle materials. That is, the coefficient of thermal expansion of ODS steel is typically about 11 × 10 ⁻⁶ / K at room temperature.
The thermal expansion coefficient of F82H steel is 10 to 11 × 10 ⁻⁶ / K at 20 ° C. (room temperature). The ODS steel and the F82H steel have different thermal expansion coefficients depending on the components contained and the ratio thereof. For this reason, the coefficient of thermal expansion varies, and this value should be understood as a representative example.

  Thus, if the magnitude relationship between the thermal expansion coefficients of the steel-based material and the brittle material is determined at room temperature (or 25 ° C.), the magnitude relationship does not change even in the phase transformation temperature range. For this reason, in this specification, the magnitude relationship between the thermal expansion coefficients of the steel-based material and the brittle material is defined at room temperature (or 25 ° C.).

(Transformation superplastic material)
The transformation superplastic material made of carbon steel is preferably one that causes phase transformation-induced creep deformation in the phase transformation temperature range, that is, one having a thermal stress relaxation mechanism. In addition, the transformation superplastic material made of carbon steel preferably has a yield strength lower than the yield strength of the steel-based material and the brittle material in order to increase the adhesion to the joint surface to the steel-based material and the brittle material.

  Superplasticity is a phenomenon in which a solid is deformed to several hundred% or more when deformed at a constant strain rate in a high temperature range. There are two types of superplasticity: transformation superplasticity resulting from phase transformation of the material and fine grain superplasticity occurring in a polycrystalline material having a crystal grain size of several μm or less. The present invention is directed to a transformed superplastic material having a transformed superplasticity resulting from the phase transformation of the material.

  The phase transformation temperature range here is a temperature at which austenite (γ phase) completes transformation to ferrite (α phase) or transformation to ferrite (α phase) and cementite during cooling. Hereinafter, the transformation in this temperature range is simply referred to as phase transformation.

In the joined body 10, the transformed superplastic material is used as an intermediate material inserted between the brittle material and the steel material, and becomes the transformed superplastic material layer 40.
An example of this type of transformation superplastic material is S50C steel with a carbon concentration of 0.5%. S50C steel exhibits the phase transformation described above in the phase transformation temperature range (740 to 680 ° C.) during cooling in the post-heat treatment after the diffusion joining treatment (joining temperature 1240 ° C.) (see FIG. 13). FIG. 13 is an Fe—C binary equilibrium diagram, in which the phase transformation in post-heat treatment of S50C steel is indicated by an arrow.

In addition to S50C steel, the following carbon steel can be cited as a transformation superplastic material.
S10C (phase transformation temperature range: 850-780 ° C.), S12C (phase transformation temperature range: 845-770 ° C.), S15C (phase transformation temperature range: 845-770 ° C.), S17C (phase transformation temperature range: 815-730 ° C.) ), S20C (phase transformation temperature range: 815 to 730 ° C.), S22C (phase transformation temperature range: 815 to 730 ° C.), S25C (phase transformation temperature range: 815 to 730 ° C.), S28C (phase transformation temperature range: 780 to 780 ° C.) 720 ° C), S30C (phase transformation temperature range: 780 to 720 ° C), S33C (phase transformation temperature range: 770 to 710 ° C), S35C (phase transformation temperature range: 770 to 710 ° C), S38C (phase transformation temperature range: 760-700 ° C), S40C (phase transformation temperature range: 760-700 ° C), S43C (phase transformation temperature range: 750-680 ° C), S45C (phase transformation temperature range: 750-680 ° C), S48 (Phase transformation temperature range: 740 to 680 ° C), S53C (Phase transformation temperature range: 740 to 680 ° C), S55C (Phase transformation temperature range: 740 to 680 ° C), S58C (Phase transformation temperature range: 730 to 680 ° C) , S09CK (phase transformation temperature range: 850 to 780 ° C.), S15CK (phase transformation temperature range: 845 to 770 ° C.), S20CK (phase transformation temperature range: 815 to 730 ° C.)
All of the above carbon steels exhibit phase transformation in the phase transformation temperature range.

In addition, these carbon steel is mentioned typically, It is not limited to these, What is necessary is just another carbon steel and what has a phase transformation temperature range.
(Operation of the first embodiment)
The joined body 10 configured as described above includes a brittle material layer 20 and a steel-based material layer 30 having different thermal expansion coefficients, and a transformed superplastic material between the brittle material layer 20 and the steel-based material layer 30. Layer 40 is inserted.

  Then, the brittle material layer 20 and the steel-based material layer 30 are heated (heated) to a diffusion bonding temperature exceeding the phase transformation temperature range of the transformation superplastic material layer 40 and held for a predetermined time, Atomic interdiffusion is promoted for diffusion bonding. Further, the thermal stress generated during the subsequent cooling is relaxed by the transformed superplastic material layer 40 by the post heat treatment.

This embodiment has the following features.
(1) The joined body 10 of the present embodiment includes a brittle material layer 20 having a low thermal expansion coefficient and a steel material layer 30 having a large thermal expansion coefficient, and is a joined body in which both are diffusion bonded. Further, a transformation superplastic material layer 40 made of carbon steel is inserted between the brittle material layer 20 and the steel-based material layer 30. As a result, the joined body 10 of this embodiment has no fear of embrittlement of the base material, and the thermal stress generated in the cooling process after joining is removed by the transformation superplastic material layer, thereby improving the joining strength. Can be achieved.

  (2) In the joined body 10 of the present embodiment, the brittle material layer 20 is a heat receiving portion that receives heat input, and the steel-based material layer 30 is a gradually heating portion that gradually heats the heat from the heat receiving portion. As a result, the heat from the brittle material layer 20 can be gradually heated through the steel material layer 30.

  (3) According to this embodiment, the transformation superplastic material (intermediate material) made of carbon steel has a chemical composition that is not significantly different from that of a steel-based material (joint base material), and therefore has mechanical properties at the joint interface. There is no significant difference from the base material. For this reason, unlike the case of using brazing material, a high concentration of the intermediate material component is not distributed at the joint interface of the base material, so that a compound of the base material and the component diffused from the intermediate material is formed. There is no concern about the embrittlement of the base material.

(Second Embodiment)
Next, a manufacturing apparatus and a manufacturing method of the joined body will be described.
(manufacturing device)
As shown in FIG. 2, the manufacturing apparatus 50 includes a pressure hot press 60 provided in a vacuum chamber 52. In the hot press 60, a pair of punches 64 and 66 are arranged from both ends with respect to a cylindrical die 62, and both the punches 64 and 66 can be driven by a pair of cylinder mechanisms 68 and 70, respectively. ing. The die 62 and the punches 64 and 66 are made of, for example, a heat resistant material such as graphite. However, the die 62 and the punches 64 and 66 are not limited to graphite as long as the material is a heat resistant material.

In the present embodiment, the pair of punches 64 and 66 and the pair of cylinder mechanisms 68 and 70 constitute a compressive stress applying unit.
The cylinder mechanisms 68 and 70 drive the cylinder mechanisms 68 and 70 by the control unit 80 controlling the hydraulic circuit 72. An induction heating coil 84 is wound around the die 62. The induction heating coil 84 can be controlled by the induction heating coil 84 when the control unit 80 drives and controls the current supply unit 82. In this case, the heating is performed until the diffusion bonding temperature of the brittle material and the steel material is reached. This diffusion bonding temperature is a temperature exceeding the phase transformation temperature range of the transformed superplastic material. The induction heating coil 84 is an example of a heating unit. In this embodiment, the die 62, the punches 64 and 66, and the induction heating coil 84 constitute a heating furnace.

  Further, the control unit 80 controls the induction heating coil 84 to heat up to the diffusion bonding temperature of the brittle material and the steel-based material, and controls the displacement of the compressive stress applying unit during the heating so that the transformation superplastic material is obtained. Control to give only deformation. In addition, the control unit 80 joins the brittle material and the steel material, and then performs cooling by post heat treatment. That is, after cooling is performed by cycle treatment, slow cooling treatment, or the like in the phase transformation temperature range of the transformed superplastic material, the temperature is lowered to room temperature to obtain a joined body.

The post heat treatment will be described later.
(Production method)
Next, the manufacturing method of the joined body 10 will be described together with the operation of the manufacturing apparatus 50.

  When the joined body 10 is manufactured, a brittle material, a steel-based material, and a transformation superplastic material are arranged in layers in the die 62 of the manufacturing apparatus 50. At this stage, the inside of the vacuum chamber 52 is in a non-vacuum state, and the transformation superplastic material is inserted between the brittle material and the steel material in the die 62. Thereafter, the vacuum chamber 52 is evacuated.

Next, a step of diffusing junction with said steel-based material with brittle material, do the following.
That is, the control unit 80 controls the hydraulic circuit 72 and the current supply unit 82 to pressurize the materials arranged in layers by the punches 64 and 66 through the cylinder mechanisms 68 and 70, and to the diffusion bonding temperature. The induction heating coil 84 is heated to reach.

The pressure applied by the punches 64 and 66 is controlled by the control unit 80 so that only the transformed superplastic material is deformed.
The controller 80 maintains the temperature for a predetermined time after the temperature is increased by the induction heating coil 84 to the diffusion bonding temperature. By maintaining the diffusion bonding temperature for this predetermined time, the brittle material and the steel-based material are diffused and joined by promoting atomic interdiffusion. When the temperature is increased to the diffusion bonding temperature, the transformed superplastic material made of carbon steel changes to austenite (γ phase). The predetermined time is a time during which the diffusion bonding is sufficiently performed, and may be set according to the type and amount of the brittle material and the type and amount of the steel material.

After the predetermined time has elapsed, the control unit 80 performs post heat treatment during cooling.
In the subsequent heat treatment, the control unit 80 controls the induction heating coil 84 to cycle the phase transformation temperature range (hereinafter referred to as cycle treatment), slow cooling treatment, and rapid cooling to the phase transformation temperature range. There is a method of maintaining the temperature at a temperature near the lower limit of the phase transformation temperature range (hereinafter, rapid cooling treatment).

In the method of cycling the cycle phase transformation temperature range, for example, about 9 to 12 cycles are preferable with a temperature fluctuation of 40 to 650 ° C./min, but it is not limited.
The cycle treatment may be performed without leaving the phase transformation temperature range, or may be performed so as to include the phase transformation temperature range, that is, exceeding the upper limit value and the lower limit value of the phase transformation temperature range.

Moreover, the slow cooling process is, for example, a single cooling at 1.6 ° C./min. This numerical value is illustrative and not limiting.
By this post heat treatment, the bonding strength between the layers depends on the accumulated time exposed to the phase transformation temperature range.

  After this, heat treatment is performed in the phase transformation temperature range, so the transformed superplastic material undergoes transformation from austenite (γ phase) to ferrite (α phase), etc. during cooling, and when this transformation is performed, the phase transformation Induced creep deformation is performed to reduce thermal stress generated during cooling.

  That is, although a thermal stress is generated in the joined body due to a difference in thermal expansion coefficient between the brittle material and the steel-based material, the thermal stress increases with cooling. At this time, the transformed superplastic material undergoes a phase transformation of γ phase → α phase in the phase transformation temperature range. Since the α phase generation in the γ phase is accompanied by volume expansion, dislocations are generated around the α phase in order to relax the elastic stress caused by the volume expansion. These dislocations move in a direction that eliminates the gradient of thermal stress generated in the transformed superplastic material. In this thermal stress relaxation mechanism, the greater the thermal stress, the more plastic deformation is induced, and this plastic deformation is high-temperature creep that acts under thermal stress. For this reason, the longer the time of exposure to the phase transformation temperature range, the more creep deformation progresses (phase transformation induced creep deformation), and as a result, the thermal stress is sufficiently relaxed.

  During the subsequent heat treatment, an external force is not applied by the punches 64 and 66, and the relaxation is spontaneously continued using only the thermal stress as a driving force. After the post heat treatment is completed, the temperature is lowered to room temperature.

In this way, a joined body with reduced thermal stress is obtained.
(Example)
Next, an embodiment will be described with reference to FIGS. 3, 4, and 5.

Examples 1-4 used the following materials.
・ Brittle material: Tungsten W (Estan (registered trademark) manufactured by Nippon Tungsten Co., Ltd.)
Transformation superplastic material (intermediate material): S50C steel (Fe-0.5C-0.75Mn-0.2Si),
- Steel material: ODS steel ((Fe-15% Cr- 2% W-0.2% Ti-0.35% Y 2 O 3) ( manufactured by KOBELCO Co.))
In the comparative example, pure iron was used as an intermediate material instead of the transformed superplastic material.

The brittle material was 2 mm thick, the intermediate material was 1 mm thick, and the steel material was 2 mm thick.
And using the said manufacturing apparatus, the compression pressure was applied to the material with the compressive stress of 10-50 MPa during the temperature rising period, and it heated to the diffusion joining temperature (1240 degreeC).

In addition, the phase transformation temperature range of the transformation superplastic material in an Example is 740-680 degreeC.
As shown in FIG. 3, up to the diffusion bonding temperatures of Examples 1 to 4 and the comparative example, the induction heating coil 84 is controlled and heated at the same heating rate over 40 minutes from room temperature RT (25 ° C.), After reaching the diffusion bonding temperature, cooling was started after holding for a predetermined time (in the example, 60 minutes).

(About post heat treatment)
In Example 1, the cooling is started at 64 ° C./min and the temperature of the joined body reaches 800 ° C., so that the temperature change rate is in the range of 800 to 600 ° C. and the temperature change rate is 650 ° C./min. The heating coil 84 was controlled and the cycle was performed 10.5 times. In addition, this temperature range 800-600 degreeC is a range where the phase transformation temperature range includes 740-680 degreeC. After the cycle treatment, it was naturally cooled to room temperature in a furnace.

  In Example 2, the induction heating coil 84 is controlled so that the temperature change rate is 40 ° C./min in the temperature range of 800 to 600 ° C. after the cooling starts and the temperature of the joined body reaches 800 ° C. The cycle was performed 10.5 times. After the cycle treatment, it was naturally cooled to room temperature (see FIG. 3).

  Example 3 is an example of a rapid cooling process, and after starting cooling, the induction heating coil 84 is controlled to be 40 ° C./min, rapidly cooled to 600 ° C., and after reaching 600 ° C., After maintaining this temperature and starting cooling for 130 minutes, it was naturally cooled to room temperature.

  Example 4 is an example of gradual cooling treatment, and after starting cooling, the induction heating coil 84 is controlled to be 1.6 ° C./min, gradually cooled to 600 ° C., cooling is started, and 130 is reached. After a minute, it was naturally cooled to room temperature (see FIG. 3).

  In the comparative example, after the start of cooling as in Example 3, the induction heating coil 84 is controlled so as to be 40 ° C./min, rapidly cooled to 600 ° C., and after reaching 600 ° C., it is naturally cooled to room temperature. Cooled down.

(Evaluation)
Next, a micro four-point bending strength test of Examples 1 to 4 and a comparative example and a tensile test of an intermediate material will be described.

(Fine 4-point bending strength test)
As shown in FIG. 4, the test piece S of the joined body used for the micro four-point bending strength test has a width of 2.4 mm, a thickness of 0.5 mm, and an overall length of 5.0 mm. The intermediate material has 1.0 mm, and the other members have 2.0 mm.

  On the other hand, as shown in FIG. 5, in the micro four-point bending strength test apparatus 100, two push pins 102 and 103 are placed on the top surface of the test piece base 101 at intervals of 3.0 mm. The pins 102 and 103 are formed in a cylinder having a diameter of 0.5 mm.

  The upper load jig 105 has two load action pins 107 and 108 with a spacing of 0.8 mm on the bottom surface. The load acting pins 107 and 108 are formed in a cylindrical shape having a diameter of 0.5 mm.

  As shown in FIG. 5, the position of the test piece S on the test piece receiving base 101 is regulated by a guide 110 fixed to the test piece receiving base 101 and placed on the push pins 102 and 103. Is done. That is, the push pin 102 supports the lower surface of the test piece S separated by 0.25 mm from the end face of the brittle material (tungsten W), while the push pin 103 supports the lower surface separated by 3 mm therefrom.

  Further, the load application pin 107 of the upper load jig 105 matches the intermediate portion between the load application pins 107 and 108 at a position 0.25 mm closer to the tungsten W side from the boundary surface between the tungsten W and the intermediate material. Let

As described above, the test piece S was set in the micro four-point bending strength test apparatus 100, and a load of 122.05 g was applied to the test piece S at 1 × 10 ⁻³ mm / s at room temperature. The result is shown in FIG.

  6 (a) to 6 (d) show the magnitude of the fracture stress by the micro bending strength test of Examples 1 to 4. FIG. In the figure, CP-1, CP-2, CP-3, and CP-4 mean the test pieces S of Examples 1 to 4. The dotted line is an average value of the plurality of test pieces S, and the solid line indicates the maximum value among them.

In Example 1, the average value was 260 MPa and the maximum value was 290 MPa.
In Example 2, the average value was 364 MPa and the maximum value was 375 MPa.
In Example 3, the average value was 287 MPa, and the maximum value was 373 MPa.

In Example 4, the average value was 377 MPa and the maximum value was 478 MPa.
6A to 6D, the comparative example using pure iron as the intermediate material had an average value of 324 MPa.

Thus, in the case of the Example which uses the transformation superplastic material which consists of carbon steel as an intermediate material, and the comparative example which uses pure iron, the fracture stress had a suitable value.
Moreover, it can be seen from the results of Examples 1 and 2 that the fracture stress does not depend on the cyclic heat treatment (number of cycles, cooling rate) induced by transformation superplasticity.

Moreover, in the slow cooling process shown in Example 2 and Example 4, the fracture | rupture stress larger than the case of pure iron was obtained for both the average value and the maximum value.
FIG. 7 shows a cycle treatment (10 times) in the post-heat treatment as in Example 2. After the test piece S was manufactured by changing the accumulated time of the treatment time, the microbending strength test was conducted. The fracture stress of was measured.

  In FIG. 7, the average value of the manufactured specimens S is indicated by ● and the maximum value is indicated by ◇ at different cumulative times. As shown in FIG. 7, it can be seen that a heat treatment in which the transformation continues for a longer time is the most effective for both the average value and the maximum value.

(Intermediate tensile test)
In order to see the mechanical properties of the intermediate material, tensile tests were performed on S50C steel as the intermediate material and pure iron used in the comparative example. FIG. 8 shows the shape and size of the test piece used in the tensile test of the intermediate material. The size of the test piece here was as follows as shown in FIG.

Total length: 16 mm, thickness: 0.5 mm, end width: 4.0 mm, parallel length: 5.0 mm, parallel width: 1.2 mm, shoulder radius: 1.5 mm, end To parallel part: 5.5mm
FIG. 9 shows the result of the tensile test, in which the vertical axis represents the yield stress. As shown in FIG. 9, S50C steel and pure iron have a difference of 310 MPa, and S50C steel has a large yield stress. As a result, it can be seen that S50C steel contributes as a relaxation material. In this case, deformation in S50C steel is not a common yielding phenomenon.

From the above test results, the following can be understood.
That is, in the thermal stress relaxation mechanism in the joined body of the comparative example using pure iron as an intermediate material, the deformability is improved by having a yield stress lower than that of S50C steel. It contributes to the relaxation of

  On the other hand, in the thermal stress relaxation mechanism in the joined body of the example using S50C steel as an intermediate material, the yield stress is high and the deformability is lower than that of pure iron. It is suggested that thermal stress relaxation is performed.

This embodiment has the following features.
(1) The joined body manufacturing apparatus 50 according to this embodiment uses a pair of punches 64 and 66 and a pair of cylinder mechanisms 68 and 70 to transform superplasticity made of carbon steel between a brittle material and a steel-based material. In a state where the material is arranged as an intermediate material, a compressive stress applying portion that applies a compressive pressure to the brittle material and the steel material is configured. In addition, the manufacturing apparatus 50 includes an induction heating coil 84 (heating unit) that heats the brittle material and the steel material.

  In addition, the manufacturing apparatus controls the induction heating coil 84 (heating unit) to heat up to the diffusion bonding temperature of the brittle material and the steel material, and controls the displacement of the compressive stress applying unit during the heating. Have. Moreover, the control part 80 gives a deformation | transformation only to an intermediate material, joins tungsten and S50C steel, and performs cooling by the cycle process or slow cooling process in the phase transformation temperature range of an intermediate material after that.

  As a result, the joined body manufacturing apparatus of the present embodiment eliminates the risk of embrittlement of the base material, and can remove the thermal stress generated in the cooling process after joining, thereby improving the joining strength. A joined body can be manufactured suitably.

(2) The manufacturing method of the joined body of this embodiment includes the brittle material layer 20 having a small thermal expansion coefficient and the steel-based material layer 30 having a large thermal expansion coefficient, and a joined body manufacturing method in which both are joined by diffusion bonding. And it has the step which inserts the transformation superplastic material which consists of carbon steel as an intermediate material between a brittle material and steel-type material. Further, the production method includes the steps of diffusing junction a brittle material and steel material, after diffusion bonding, and steps to mitigate the residual thermal stress of the brittle material.

  As a result, according to the manufacturing method of the present embodiment, there is no risk of embrittlement of the base material, and the joined body that can improve the joining strength by removing the thermal stress generated in the cooling process after joining is obtained. It can manufacture suitably.

(3) The manufacturing method of the joined body of the present embodiment includes a brittle material having a small thermal expansion coefficient and a steel-based material having a large thermal expansion coefficient, and is a manufacturing method of a joined body that joins both by diffusion bonding, A step of inserting a transformation superplastic material (S50C steel) as an intermediate material between a brittle material (tungsten) and a steel-based material (ODS steel) is provided. Further, the method includes the step of diffusing junction brittle material and (tungsten) and steel material (ODS steel), after diffusion bonding, comprising the step of relaxing the residual thermal stress of brittle material (tungsten) .

As a result, according to the present embodiment, the residual thermal stress of the brittle material (tungsten) can be relaxed after diffusion bonding.
(4) In the method for manufacturing the bonded body of the present embodiment, the step of diffusing junction is carried out at a temperature above the phase transformation temperature range of the intermediate member. In addition, the step of relieving the residual thermal stress of the brittle material is carried out by performing post-heat treatment in the phase transformation temperature range of the intermediate material after diffusion bonding is performed at a temperature exceeding the phase transformation temperature range, thereby causing the brittle material by phase transformation-induced creep deformation. Relieve thermal stress between steel and steel materials.

As a result, according to this embodiment, at a temperature above the phase transformation temperature range of the intermediate member, the post heat treatment after providing to perform the diffusion junction, preferably the thermal stresses between the brittle material and steel material Can be relaxed.

  (5) In the manufacturing method of the joined body of this embodiment, the post-heat treatment is a cycle treatment or a slow cooling treatment in the phase transformation temperature range of the intermediate material. As a result, according to the present embodiment, the thermal stress between the brittle material and the steel-based material can be suitably relaxed by the cycle process or the slow cooling process in the phase transformation temperature range of the intermediate material.

(Third embodiment)
Next, the structure will be described with reference to FIG.
The structure of FIG. 10 is a flat plate type in which a brittle material layer 90, a transformation superplastic material layer 92, and a steel-based material layer 93 are each formed into a flat plate, and the steel-based material layer 93 is coated with steel. A tube 94 made of metal is arranged so as to extend in a direction perpendicular to the stacking direction.

The brittle material layer 90 is a heat receiving part, and the steel material layer 93 constitutes a gradual heating part. The tube 94 is a heat medium passage. Examples of the heat medium include pressurized water, molten salt Flabe (LiF-BeF ₂ mixed fluoride molten salt), and the like. In addition, as a heat medium, it is not limited to the above-mentioned thing, Another heat medium may be sufficient.

  The structure of the present embodiment is a cooler using a steel-based material layer as a heat sink, and can be used, for example, in a blanket of a nuclear power generation reactor, and can cope with a high heat load. That is, the heat input by the brittle material layer 90 as the heat receiving portion can be gradually heated by the heat medium flowing in the tube 94 in the steel-based material layer 93 as the gradually heating portion.

This embodiment has the following features.
(1) The structure of this embodiment has a heat medium passage part (tube 94) through which the heat medium passes in the gradually heating part (steel-based material layer 93), and heat from the gradually heating part. The heat medium flowing through the heat medium passage part is further gradually heated. As a result, according to this embodiment, in the steel-based material layer that is the gradually heating part, it is possible to gradually heat with the heat medium flowing in the heat medium passing part.

In addition, embodiment of this invention is not limited to the said embodiment, You may change as follows.
In the manufacturing apparatus 50 of the embodiment, the compressive stress applying portion includes the pair of punches 64 and 66 and the pair of cylinder mechanisms 68 and 70. However, in the configuration of the embodiment, one punch and the punch It is good also considering the structure which abbreviate | omitted the cylinder mechanism which drives A as a compressive-stress provision part.

-In 3rd Embodiment, although the structure was made into the flat plate type, you may change a structure into the saddle type structure shown in FIG.
That is, as shown in FIG. 11, the upper half of the tubular transformation superplastic material layer 92 is fitted into an inverted U-shaped groove provided on the joint surface side of the brittle material layer 90. .

  Further, the lower half of the transformed superplastic material layer 92 is fitted in a U-shaped groove of the steel-based material layer 93b. A steel-based material layer 93a is formed in a tubular shape in the transformed superplastic material layer 92, and a tube 94 through which the heat medium passes is disposed.

  The steel material layer 93 b is also bonded to the lower surface of the brittle material layer 90. Although not shown in FIG. 11, an intermediate material may be interposed at the joint between the lower surface of the brittle material layer 90 and the steel-based material layer 93b, and the influence of thermal stress depends on the thickness of the tungsten W. When there is no, it may be joined via a brazing material as in the conventional case.

In the example of FIG. 11, since the joint surface of the brittle material layer 90 on the transformation superplastic material layer 92 side is formed in an inverted U shape, the generated thermal stress can be reduced.
Similar to the third embodiment, the structure of the present embodiment can be used in a blanket of a fusion power reactor and can cope with a high heat load. In the present embodiment, the heat input by the brittle material layer 90 as the heat receiving portion is gradually heated by the heat medium flowing in the pipe 94 in the steel-based material layers 93a and 93b as the gradually heating portions. Is possible.

  In the third embodiment, the structure may be changed to a monoblock type as shown in FIG. Specifically, the brittle material layer 90 is formed in a monoblock shape, and the tubular transformation superplastic material layer 92 and the tubular steel-based material layer 93 are arranged in a two-layer structure therein.

  The structure of this example can be used in the blanket and can handle high heat loads. In addition, the heat medium of the present embodiment can gradually heat the heat input by the brittle material layer 90 as the heat receiving part with the heat medium flowing in the steel material layer 93 as the slow heat part. . In addition, in FIG. 12, it is good also as a three-layer structure by arrange | positioning a pipe | tube in the steel-type material layer 93 further.

  In the embodiment of FIGS. 10 to 12, the structure has a quadrangular cross section, but these are only examples, and are not limited to a quadrangular cross section, and may have other shapes.

10 ... Joint body, 20 ... Brittle material layer, 30 ... Steel material layer,
40 ... transformation superplastic material layer, 50 ... manufacturing equipment, 52 ... vacuum chamber,
60 ... Pressure hot press, 62 ... Dies, 64 ... Punch, 66 ... Punch,
68 ... Cylinder mechanism, 70 ... Cylinder mechanism, 72 ... Hydraulic circuit,
80 ... control unit, 82 ... current supply unit, 90 ... brittle material layer,
92 ... Transformation superplastic material layer, 93 ... Steel-based material layer, 93a ... Steel-based material layer,
93b ... Steel-based material layer, 94 ... Tube 100 ... Micro four-point bending strength test apparatus, 101 ... Test piece holder
102, 103 ... push pins, 105 ... upper load jig,
107, 108: Load acting pin, 110: Guide.

Claims (5)

In a joined body including a brittle material having a small coefficient of thermal expansion and a steel-based material having a large coefficient of thermal expansion, both of which are diffusion-bonded,
Ri Na transformation superplastic material consisting of carbon steel between the steel material and the brittle material is inserted as an intermediate material,
The layer made of the brittle material serves as a heat receiving part that receives heat input,
The layer made of the steel material is a gradually heating part that gradually heats the heat from the heat receiving part,
In the slow heating part, it has a heat medium passage part through which the heat medium passes,
The joined body in which the heat medium flowing through the heat medium passage part further gradually heats the heat from the gradual heat part . A structure including the joined body according to claim 1 ,
A structure having a flat plate shape in which the brittle material, the transformed superplastic material, and the steel material are laminated in layers . It includes a brittle material having a small coefficient of thermal expansion and a steel material having a large coefficient of thermal expansion, and is a manufacturing apparatus for a joined body in which both are diffusion bonded,
A compressive stress applying unit that applies compressive pressure to the brittle material and the steel material in a state where a transformation superplastic material made of carbon steel is disposed as an intermediate material between the brittle material and the steel material. When,
A heating section for heating the brittle material and the steel material;
Heating control of the heating part, heating to the diffusion bonding temperature of the brittle material and the steel-based material, controlling the displacement of the compressive stress applying part during the heating, giving deformation only to the intermediate material, An apparatus for manufacturing a joined body, comprising: a control unit that joins the brittle material and the steel-based material, and then cools the intermediate material by cycle treatment or slow cooling treatment in a phase transformation temperature range. In a manufacturing method of a joined body that includes a brittle material and a steel-based material having different coefficients of thermal expansion, and that joins both by diffusion bonding,
Inserting a transformation superplastic material made of carbon steel as an intermediate material between the brittle material and the steel material;
A step of diffusing junction with said steel-based material and the brittle material,
Relaxing the residual thermal stress of the brittle material after the diffusion bonding;
Only including,
The step of diffusion bonding is performed at a temperature exceeding the phase transformation temperature range of the intermediate material,
The step of relieving the residual thermal stress of the brittle material is performed by post-heat treatment in the phase transformation temperature range of the intermediate material after the diffusion bonding is performed at a temperature exceeding the phase transformation temperature range, and by the phase transformation induced creep deformation. The manufacturing method of the joined body which relieves the thermal stress between a brittle material and the said steel-type material . The method for manufacturing a joined body according to claim 4 , wherein the post heat treatment is a cycle treatment or a slow cooling treatment in a phase transformation temperature range of the intermediate material.