KR20160086465A

KR20160086465A - Metalic bonding using servo motor friction welding and the bonding method thereof

Info

Publication number: KR20160086465A
Application number: KR1020150003343A
Authority: KR
Inventors: 오명훈; 박종문; 김기영; 김준영
Original assignee: 금오공과대학교 산학협력단
Priority date: 2015-01-09
Filing date: 2015-01-09
Publication date: 2016-07-20

Abstract

The present invention relates to a bonded body of dissimilar metals using servo motor friction welding, and more particularly to a method of joining two kinds of bonding members made of dissimilar metals using servo motor friction welding, And a feeding speed (a friction time), a pressing distance, and a pressing speed (upsetting pressure), thereby improving bonding strength.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a bonded body of a dissimilar metal by friction welding of a servo motor,

The present invention relates to a bonded body of dissimilar metals using servo motor friction welding and a bonding method thereof, and more particularly, to a bonding body of two kinds of bonding members made of dissimilar metals using servo motor friction welding, (Friction time), a pressing distance and a pressing speed (upsetting pressure), and the like, thereby improving the bonding strength.

Friction welding is a solid state welding method in which a material to be bonded is rotated at a high speed, and then the two materials are rubbed together and the contact surfaces of the two materials reach a sufficient temperature for frictional heat. Friction welds can be easily joined between dissimilar metals as well as like metals.

Friction welding generates frictional heat only at the contact surface. Therefore, the Heat Affect Zone (HAZ) of the base material is narrow, and the plastic is deformed at the contact surface by applying pressure before melting. During the rubbing, the contact surfaces are sputtered to remove the oxides of the surface and to clean the bonding surfaces. In addition, since the bonding temperature is low, solid phase bonding is obtained, and the bonding property is excellent because of the coarsening of the metal crystal and the intermetallic compound. Especially, friction welding is possible not only for the same kind of material but also for the bonding of dissimilar materials having different properties, and there is no environment harmful circle since arc, fume and gas are not generated during welding

Conventional hydraulic friction welding machine is a facility produced in Japan. The driving conditions for the most important pressure in friction welding differs from equipment to equipment, so that there are differences in process conditions by equipment model.

Such friction welding methods are made in various forms depending on the object to be rotated or the method of applying pressure. For example, in the patent document 10-2011-78518, a first joining member made of different materials and a second joining member are brought into contact with each other, and a rotating rotary stone moves along a joining interface thereof to apply frictional force and pressure, A friction welding method and apparatus for dissimilar materials in which a bonding material and a second bonding material are bonded to each other so that bonding quality is uniform by disposing a backing plate having a different thermal conductivity on the back surfaces of the first bonding material and the second bonding material, .

However, the above-mentioned conventional friction welding method requires a rotating and pressing member such as a rotating stone in addition to the two kinds of joining members, and is not applicable to a target having a specific shape such as a turbine blade and a turbine shaft.

In addition, TiAl alloy, which is currently attracting attention as a light-weight heat-resistant material, has a bonding strength of 120 MPa or less in friction welding without using an insert material by using a hydraulic method with a structural tool steel SCM440, Research is needed to increase the bonding strength.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above-described problems, and it is an object of the present invention to provide a method of joining two kinds of joining members made of different materials by controlling the feed distance and speed using servo motor friction welding, And a bonding method of the same.

To this end, the present invention comprises a first step of inserting and fixing the first joining member and the second joining member to the chuck of the main shaft and the clamp side of the servo motor friction welding machine, respectively; Two steps of rotating the first joining member and forwarding the second joining member toward the first joining member to rub the contact surfaces of the first joining member and the second joining member; And a third step of bonding the first bonding member and the second bonding member by applying pressure to the second bonding member after stopping the first bonding member, wherein the first bonding member comprises TiAl (wherein Ti And Al is an alloy of Ti: Al = 51 to 52: 48 to 49), and the second joint material is an SCM440 alloy steel. The present invention also provides a method of joining dissimilar metals using friction welding.

In a preferred embodiment of the present invention, the rotation may be performed using a rotary servo motor.

In a preferred embodiment of the present invention, the pressure may be applied using a servo motor for pressurization.

In a preferred embodiment of the present invention, in the second step, the first joining member is rotated at 1000 to 5000 rpm and the second joining member is conveyed at a conveying distance of 5 to 15 mm at a conveying speed of 10 to 150 mm / min To the first joining member.

In a preferred embodiment of the present invention, the pressing speed in the third step may be 1000 to 5000 mm / min.

In a preferred embodiment of the present invention, the bonding of the third step may be performed by applying pressure so that the second bonding material is shortened by 5 to 15 mm.

Another aspect of the present invention is a bonded body in which a first bonding member and a second bonding member are bonded,

Wherein the first bonding material is an alloy of TiAl (wherein the content ratio of Ti and Al is Ti: Al = 51 to 52: 48 to 49), the second bonding material is an SCM440 alloy steel, And a thermally deformable layer. The present invention also provides a bonded body of dissimilar metals.

In a preferred embodiment of the present invention, the thermally-deformable layer has a duplex microstructure in which the? -Granular grain and? /? 2 are mixed in the TiAl alloy portion, and the martensite structure in the SCM440 portion.

In a preferred embodiment of the present invention, the thickness of the thermally-deformable layer is 0.5 mm to 1.0 mm, and the intermetallic compound layer may be 0.1 mm or less.

In a preferred embodiment of the present invention, the bonding strength in the range of 0.1 mm to 0.5 mm from the central axis of the cross section of the thermally deformable layer toward the second bonding member may be 250 MPa to 400 MPa.

In a preferred embodiment of the present invention, the tensile strength of the bonded body of the dissimilar metal may be 250 MPa to 350 MPa.

In a preferred embodiment of the present invention, the joined body can be bonded in the above-described manner.

Another aspect of the present invention provides an automotive turbine shaft including the above joined body.

According to the joining method of dissimilar metals using the sub-motor friction welding of the present invention, when the second joining member is pressed while rotating the first joining member, the servo motor type friction welding is used to adjust the rotation speed, the feed distance, Time, pressurizing distance, and pressing speed (upsetting pressure) can be finely adjusted, so that a dissimilar metal bonded body improved in mechanical strength at the joint surface can be manufactured.

In addition, by providing a turbine shaft for an automobile including a bonded body of dissimilar metals manufactured by the above method, the turbine shaft according to the present invention can be driven by an electric motor inside the turbocharger, And at the high speed, the compressor can be driven using the rotational force of the turbine rotating by the exhaust gas

1 is a schematic view of a servo motor type friction welding machine used in an embodiment of the present invention.
2 is a schematic view of a tensile specimen used in an embodiment of the present invention.
Figure 3 is an image of a homogeneous and dissimilar metal friction welding tensile specimen used in an embodiment of the present invention.
4 is an image of a homogeneous and dissimilar metal friction welding cut specimen used in an embodiment of the present invention.
5 is a tensile strength test graph of a specimen and a raw material according to an embodiment of the present invention.
6 is a tensile strength test graph of Example 5 and Example 6 of the present invention.
7 is an FE-SEM image of the microstructure analysis result of Comparative Example 1. Fig.
8 is an FE-SEM image of a microstructure analysis result of Comparative Example 3. Fig.
9 is an FE-SEM image of a microstructure analysis result of Example 5 of the present invention.
10 is a microstructure image of the bonding surface of Example 5 of the present invention.
11 is an image of a microstructure and an EDS analysis result of Example 5 of the present invention.
12 is an XRD analysis result image of Example 5 of the present invention.
13 is a hardness analysis graph of Example 5. Fig.

As described above, the conventional friction welding method is divided into a friction type and a driving energy, and is generally divided into a direct drive type and a flywheel type. However, in the present invention, by using the servo motor type friction welding machine (see Fig. 1) developed by AFW Co., Ltd. in 2010, it is possible to finely control the rotation speed, the feed distance, the friction time and the upset pressure, A dissimilar metal bonded body having improved strength can be produced.

More specifically, the servo motor type friction welding machine is similar to a brake type friction welding machine, but uses a servomotor instead of a rotating electric motor and a hydraulic cylinder to pressurize. In a brake type friction welding machine using hydraulic pressure, However, the servomotor type friction welding machine is capable of finely controlling the rotation speed, the feed distance and the feed speed (friction time), the pressing distance and the pressing speed (upsetting pressure), and the rotary chuck, the fixing chuck, A disk-type brake device for suddenly stopping the rotation, a servo motor device for obtaining pressing force and rotational force, and a hydraulic device for operating the chuck of the main shaft and the chuck of the clamp side.

The dissimilar metal bonded body according to the present invention can be manufactured using the servo motor type friction welding machine. In the method of joining dissimilar metals using the servo motor friction welding according to the present invention, the first bonding member and the second bonding member are connected to the servo motor A first step of inserting and fixing the main shaft of the friction welding machine and the chuck of the clamp side, respectively; Two steps of rotating the first joining member and forwarding the second joining member toward the first joining member to rub the contact surfaces of the first joining member and the second joining member; And stopping the first joining member and applying pressure to the second joining member to join the first joining member and the second joining member. Hereinafter, the present invention will be described in more detail by step.

In the method of joining dissimilar metals using servo motor friction welding according to the present invention, the first step is a step of inserting and fixing the first bonding member and the second bonding member to the chuck of the main shaft and the clamp side, The first joining member inserted and fixed in the chuck of the main shaft is rotated and the second joining member inserted and fixed in the chuck on the clamp side is advanced and conveyed toward the first joining member fixed to the chuck of the main shaft Friction may be caused after the first bonding member and the second bonding member are brought into contact with each other.

At this time, it is preferable that the first bonding member and the second bonding member can be manufactured using a different kind of metal, the first bonding material is a TiAl alloy, and the second bonding material is an SCM440 alloy steel. At this time, it is preferable that the content ratio of Ti and Al is in the range of Ti: Al = 51 to 52: 48 to 49. If the Ti-Al alloy steel is out of the above range, the microstructure and mechanical properties of the TiAl alloy steel vary, good. The joined body of the joining members can exhibit excellent mechanical characteristics because of improved tensile strength and bonding strength.

In the method of joining dissimilar metals using servo motor friction welding according to the present invention, in the second step, the first joining member is rotated and the second joining member is advanced and conveyed toward the first joining member, And rubbing the contact surfaces of the joining member and the second joining member. According to the present invention, it is possible to control the number of revolutions, transfer distance, friction time, upset pressure, etc. of dissimilar metals by using a servo motor type friction welding machine, and by adjusting the conditions, a dissimilar metal bonded body improved in mechanical properties can be manufactured .

At this time, the rotation can be performed using a servo motor for rotation, and the number of rotations can be changed by using the servo motor. In the second step, the first joining member is rotated at 1000 to 5000 rpm, and the second joining member is advanced and conveyed toward the first joining member at a conveying speed of 5 to 20 mm at a conveying speed of 10 to 150 mm / The first joining member and the second joining member can be joined by the frictional heat so that friction is generated between the first joining member and the second joining member, and preferably, the first joining member is bonded to the first joining member at 4000 to 5000 rpm And the second joint member is advanced and conveyed toward the first joining member at a conveying speed of 10 to 15 mm at a conveying speed of 100 to 150 mm / min. At this time, it is possible to control the friction time by controlling the feed distance and the feed speed within the above range. When the two steps are performed within the above-mentioned range, a dissimilar metal bonded body having improved mechanical properties can be produced.

When the first joining member is rotated at less than 1000 rpm, there is a problem that it is difficult to generate sufficient frictional heat to bond the first and second joining members to each other, and rotation exceeding 5000 rpm is difficult to realize through a friction welding machine There is a problem. Further, when the second bonding material is forwardly transported toward the first bonding member under the condition that the second bonding material is out of the above range, there is a problem in that the bonding is not performed because the diffusion between the atoms is not performed and the bonding strength is low.

In the method of joining dissimilar metals using servo motor friction welding according to the present invention, in the step 3, after the first joining member is stopped, pressure is applied to the second joining member so that the first joining member and the second joining member Member. At this time, the pressure can be applied by using a pressing servomotor, and the pressure can be adjusted by changing the pressing distance and the pressing speed, so that the first joining member and the second joining member can be joined.

In the third step, after the first joining member is stopped, the second joining member is shortened by 5 to 15 mm by applying pressure to the second joining member at a pressing speed of 3000 to 5000 mm / min, Preferably, after the first bonding member is stopped, pressure is applied to the second bonding member at a pressing speed of 4000 to 5000 mm / min to shorten the length of 5 to 10 mm, and the molten glass of the bonding surface The first joining member and the second joining member may be joined together. If the thickness is out of the above range, thermal deformation and intermetallic compounds, impurities and the like generated on the bonding surface are not removed by beads, which results in low bonding strength.

More specifically, in the third step, the molten material formed by the frictional heat at the interface between the first bonding member and the second bonding member is hardened and can be bonded, and in the process of hardening the molten material, The alloy steel is recrystallized and thermally deformed to form a martensite structure and a heat-deformable layer containing them can be formed. The bonded body of the dissimilar metals has a duplex microstructure in which the? -Granular grains and? /? ₂ are mixed in the TiAl alloy portion at the bonding interface and the martensite structure in the SCM440 portion A thermally strained layer is formed, and an intermetallic compound layer due to diffusion of atoms can be formed. At this time, hardness can be improved due to the heat-deformable layer, but tensile strength can be lowered. Therefore, it is possible to manufacture a joined body having excellent tensile strength by minimizing the heat- desirable.

The present invention also provides a bonded body in which a first bonding member and a second bonding member are bonded to each other, wherein the first bonding member is made of TiAl (wherein the content ratio of Ti and Al is Ti: Al = 51 to 52: 48 to 49) Wherein the second bonding material is an SCM440 alloy steel, and the second bonding material comprises a heat-strainable layer and an intermetallic compound layer at an interface of the second bonding material.

The bonded body of the dissimilar metals has a duplex microstructure in which the? -Granular grains and? /? ₂ are mixed in the TiAl alloy portion at the bonding interface, and the martensite structure is included in the SCM440 alloy steel portion And an intermetallic compound layer due to diffusion of atoms can be formed. At this time, although the hardness can be improved due to the heat-deformable layer, the tensile strength can be lowered. Therefore, it is possible to manufacture a joined body having excellent tensile strength by minimizing the heat- desirable.

Therefore, the thickness of the heat-strained layer is preferably 0.1 mm to 1.0 mm, more preferably 0.1 mm to 0.5 mm. The intermetallic compound layer may be 0.1 mm or less, preferably 0.001 to 0.1 mm.

At this time, the bonding material of the dissimilar metals may have a bonding strength of 250 MPa to 400 MPa in the range of 0.1 mm to 0.5 mm in the direction of the second bonding member from the central axis of the cross section of the thermally deformable layer, and the tensile strength Has excellent physical properties from 250 MPa to 350 MPa.

Another aspect of the present invention provides an automotive turbine shaft including the above joined body. An automotive turbocharger is a device for turning the turbine by using the pressure of the exhaust gas discharged from the engine and then supplying high-pressure air to the combustion chamber using the rotational force to increase the output of the engine. At this time, the automotive turbine shaft can serve to connect between the turbine wheel and the turbine compressor in the automotive turbocharger, and the automobile joint body manufactured in the form of a round bar to be joined in the servo friction welder , The mechanical properties are improved by including the thermally deformable layer at the joint interface, and the turbine shaft having excellent durability and mechanical strength inside the turbocharger can be driven by the electric motor to drive the compressor by the electric motor at low speed torque , And the compressor can be driven using the rotational force of the turbine rotating by the exhaust gas at high speed

Hereinafter, the present invention will be described in more detail with reference to the following examples. The following examples are provided to illustrate the present invention, but the scope of the present invention is not limited by the following examples.

[ Example ]

Example 1. Preparation of dissimilar metal bonded body 1

A round rod type Φ12 TiAl alloy (51.5 at% Ti-48.5 at% Al) and Φ12 SCM440 alloy steel were respectively fixed to chucks on the main shaft and clamp side of a friction welding machine (FW-05, A.F. Thereafter, the TiAl alloy was rotated at 4000 rpm, and the SCM440 alloy steel was advanced and conveyed toward the TiAl alloy at a conveyance distance of 5 mm at a conveying speed of 40 mm / min, thereby causing friction between the joint surfaces, The joint surfaces of the Φ12 TiAl alloy (Ti-48.5 at% Al) and Φ12 SCM440 alloy steel were rubbed.

Thereafter, the main shaft chuck was stopped and the clamp side chuck was pressed at a pressing speed of 4000 mm / min to shorten the length of 10 mm. As a result, the Φ12 TiAl alloy (51.5 at% Ti-48.5 at% Al) and < 12 > SCM440 alloy steel.

Example 2 ~ 6. Preparation of dissimilar metal junctions 2

The dissimilar metals were bonded in the same manner as in Example 1 except that they were bonded under the friction welding conditions shown in Table 1 below.

division Revolutions
(rpm) Feeding distance
(mm) Feeding speed
(mm / min) Pressure distance
(mm) Pressing speed
(mm / min) Example 2

4000 8 40

10

4000 Example 3 5 40 Example 4 8 10 Example 5 12 120 Example 6 15 120

Comparative Example 1 ~ 2. Preparation of dissimilar metal junction

The metal was bonded in the same manner as in Example 1 except that? 12 SCM440 alloy steel was introduced into the main shaft of the friction welding machine and the chuck on the clamp side, and then bonded under the conditions shown in Table 2 below.

division Revolutions
(rpm) Feeding distance
(mm) Feeding speed
(mm / min) Pressure distance
(mm) Pressing speed
(mm / min) Comparative Example 1 2000
5
10 3
4000
Comparative Example 2 20

Comparative Example 3. Preparation of dissimilar metal junctions

(51.5 at% Ti-48.5 at% Al) was introduced into the main shaft of the friction welding machine and the chuck on the clamp side, and then joined according to the conditions shown in Table 3 below. Metal was bonded.

division Revolutions
(rpm) Feeding distance
(mm) Feeding speed
(mm / min) Pressure distance
(mm) Pressing speed
(mm / min) Comparative Example 3 2000 8 20 4 5000

Experimental Example 1. Dissimilar metal junction The tensile strength Measure

Tensile specimens were fabricated using C.N.C lathe for the mechanical strength test of friction welding specimens between the same and different metals of TiAl alloys and SCM440 alloy steels of Examples 1 to 6 and Comparative Examples 1 to 3. The friction welding tensile specimen was fabricated as shown in Fig. 3 with the proportional test piece No. 14A according to the tensile test specimen specification (KS B 0801) as shown in Fig. 2 because the outer diameter of the specimen (Φ12) The tensile test specimens were subjected to a tensile test at a test speed of 0.01 mm / sec using an Instron tensile tester (8801) having a maximum capacity of 10 tons. The results are shown in Table 5 below.

In order to analyze the microstructure of the heat-affected zone (HAZ) and the interface between the base material and the heat affected zone (HAZ), the test specimen was cut at 4,000 rpm using a precision cutter, And then incised with a wheel of? 03. Mounted at 180 ° C using an automatic molding machine (MECAPRESS-3, PRESI), and then polished using an automatic polishing machine (Fig. 3.18). Polishing was performed at a platen speed of 110 rpm, a rotation speed of 110 rpm, and a sample force of 10 N. The nicking conditions of the SCM440 alloy steel and the TiAl alloy were different from each other and were nicknamed under the conditions shown in Table 4 below.

division Caustic solution density Corrosion condition SCM400 alloy steel

3% Nital -
5 to 10 seconds
Ethanol (C ₂ H ₅ OH) 97 ml Nitric acid (HNO ₃₎ 3 ml TiAl caustic solution

Hydrofluoric acid (HF) 10 ml
5 to 10 seconds
Nitric acid (HNO ₃₎ 40 ml H ₂ O (DI-water) 50 ml

division Tensile strength at maximum load (MPa) Elongation (%) Young's Modulus (MPa) Yield stress
(MPa) Example 1 110.487 0.314 12541.33 91.215 Example 2 132.845 0.811 22514.315 105.184 Example 3 144.771 1.241 17521.614 133.48 Example 4 223.548 2.317 25415.221 197.24 Example 5 296.689 1.27 34396.128 230.499 Example 6 312.773 4.695 12884.2 57.5

According to Table 5, the best friction welding results were confirmed in Examples 5 and 6, in which the rotation speed was 12 mm and the feed rate was 120 mm / min. The tensile test results of TiAl and SCM440 dissimilar metal friction welding of Examples 5 and 6 are shown in Fig. According to FIG. 6, it can be seen that the weld portion of the friction welding specimen was short-circuited, and that the maximum tensile strength was 296 to 312 MPa and the yield stress was 230 MPa.

Experimental Example 2. Microstructure analysis of dissimilar metal conjugates

Field-emission scanning electron microscopy (FE-SEM, JSM-6500F, JEOL) and digital microscope (KH-8700, HIROX) were used for the microstructure analysis of the examples according to the present invention. The field emission scanning electron microscope has a resolution of 1.5 nm to 0.5 nm (at 30 kV to 20 kV) and a magnification of 10 to 500,000. The results are shown in Figs. 7 to 10. The EDX analysis was performed using an energy dispersive X-ray fluorescence spectrometer (EDX, XFlash 5010, Bruker) for the microstructure analysis of the example according to the present invention. The results are shown in FIG. 11, (SWXD (X-MAX / 2000-PC), Rigaku), and the results are shown in FIG.

Fig. 7 is a result of observing the microstructure of Comparative Example 1. As shown in Fig. 7, when microstructures of the SCM440 were observed by friction welding It can be seen that the joint material has a pearlite structure and a ferrite structure. Further, it can be confirmed that recrystallization occurred in the thermally deformable layer at the interface surface due to the frictional heat and the pressing force, and it can be confirmed that the grain size of the structure is reduced.

8 is a result of observing the microstructure of Comparative Example 3. As shown in Fig. 8, the bonding material shows a layered structure of fully lamellar, and the heat-strained layer is subjected to recrystallization to decrease the grain size I could confirm.

8 is a result of observing the microstructure of Example 5. As in Comparative Example 1, it was observed that the bonding material of SCM440 had a ferrite structure and a pearlite structure as shown in Fig. 7, It was confirmed that the lamellar structure of the lamellar was formed. More specifically, it was confirmed that thermal deformation does not occur in TiAl and thermal deformation occurs only at the joint portion of SCM440, thereby forming recrystallization and martensite structure. As a result, according to the present invention, it can be seen that the TiAl alloy is not affected by heat, and it is expected that sufficient heat transfer will be achieved in the bonding base material of the TiAl alloy when the frictional heat is rapidly increased by increasing the transfer distance and the transfer speed.

FIG. 10 is a result of observing the microstructure of the joint portion of Example 5 according to the present invention. As a result, it can be confirmed that an intermetallic compound layer is formed by atomic diffusion due to friction welding between the TiAl alloy and the SCM440 alloy steel.

In addition, it can be confirmed through the EDS component analysis image of FIG. 11 that Ti, Al, and Fe atoms are mixed in the boundary surface as a boundary. 12 shows that the intermetallic compounds such as Fe ₃ Al, Fe ₂ Ti, FeTi, and TiN are formed through the XRD analysis of the bonding interface of FIG. 12, .

Experimental Example 3. Analysis of Hardness Change of Dissimilar Metal Conjugate

In order to observe the change in hardness of the first bonding member and the second bonding member centered on the bonding interface of Example 5, Comparative Example 1 and Comparative Example 3 according to the present invention, the axial end face of the welding specimen was cut using a precision cutter And then fixed with a clamp, and then set to a load of 1.0 f using a Vickers hardness testing machine (VMT-X1, Matsuzuwa). Then, the first bonding member and the heat- The change in hardness of the second bonding member was observed. The results are shown in Fig.

13 is a graph showing changes in hardness of Example 5, and it can be seen from FIG. 13 that the hardness is improved near the bonding surface. It can be judged that the hardness is improved as the size of the structure is reduced at the joint surface, martensite structure is formed due to recrystallization and quenching, and thermal deformation is observed.

1: Main shaft Chuck 2: Clamp side Chuck
3: first joining member 4: second joining member
5: Brake 6: Servo motor for rotation
7: Servo motor for pressurization

Claims

A first step of inserting and fixing the first joining member and the second joining member to the main shaft of the servo motor friction welding machine and the chuck of the clamp side, respectively;
Two steps of rotating the first joining member and forwarding the second joining member toward the first joining member to rub the contact surfaces of the first joining member and the second joining member; And
And a third step of bonding the first bonding member and the second bonding member by applying pressure to the second bonding member after the first bonding member is stopped,
Wherein the first bonding material is a TiAl alloy wherein the content ratio of Ti and Al is Ti: Al = 51 to 52: 48 to 49, and the second bonding material is an SCM440 alloy steel. Bonding method of dissimilar metals.

The method according to claim 1,
Wherein the rotation is performed using a rotary servo motor. &Lt; RTI ID = 0.0 > 18. < / RTI >

The method according to claim 1,
Wherein the pressure is applied using a servo motor for pressurization.

The method according to claim 1,
Wherein the first joining member is rotated at 1000 to 5000 rpm in the second step and the second joining member is forwardly conveyed toward the first joining member at a conveying distance of 5 to 15 mm at a conveying speed of 10 to 150 mm / Wherein said method comprises the steps of:

The method according to claim 1,
Wherein the pressing speed in the third step is 1000 to 5000 mm / min.

The method according to claim 1,
Wherein the joining of the third step is performed by applying pressure so that the second joining member is shortened by 5 to 15 mm.

In the bonded body in which the first bonding member and the second bonding member are joined,
Wherein the first bonding material is an alloy of TiAl (wherein the content ratio of Ti and Al is Ti: Al = 51 to 52: 48 to 49), the second bonding material is an SCM440 alloy steel, A thermally deformable layer and an intermetallic compound layer.

8. The method of claim 7,
Wherein the thermally-deformable layer has a duplex microstructure in which a? -Granular grain and? /? ₂ are mixed in a TiAl alloy part, and a martensite structure in an SCM440 alloy steel part.

8. The method of claim 7,
Wherein the thickness of the thermally shrinkable layer is 0.5 mm to 1.0 mm and the intermetallic compound layer is 0.1 mm or less.

8. The method of claim 7,
And a bonding strength in a range of 0.1 mm to 0.5 mm in the direction of the second bonding member from the center axis of the cross section of the thermally deformable layer is 250 MPa to 400 MPa.

8. The method of claim 7,
Wherein the bonded body of the dissimilar metals has a tensile strength of 250 MPa to 350 MPa.

8. The method of claim 7,
Wherein the bonded body is bonded by the method of any one of claims 1 to 6. A bonded body of dissimilar metals using friction welding of a servo motor.

An automotive turbine shaft comprising the assembly of claim 7.