KR101047877B1 - Dissimilar welding method using hybrid friction stir welding system - Google Patents

Abstract

PURPOSE: A method of welding a different kind of materials using a hybrid FSW(Friction Stir Welding) system is provided to generate the sufficient plastic flow of and light alloy and a steel material by practicing TIG preheating at a steel-material welding unit when a different kind of materials, light alloy and a steel material, are welded. CONSTITUTION: A FSW tool(104) makes contact with the boundary line of first and second bases(101,102), rotates and performs welding. A TIG torch preheats a steel material of the welded unit of a different kind of materials. The bases make contact with each other to form a welded unit(103). The FSW tool is fixed to the spindle(105) of a hybrid FSW system(100). The spindle is connected to the driving shaft of a driving motor to set the number of rotation.

Description

Dissimilar materials joining method using hybrid friction stir welding system {DISSIMILAR WELDING METHOD USING HYBRID FRICTION STIR WELDING SYSTEM}

The present invention relates to a method for joining dissimilar materials using a hybrid friction stir welding system, and more particularly, hybrid friction including a TIG preheating system for preheating rolled steel for general structure among dissimilar materials (aluminum alloy + rolled steel for general structure). A method for joining dissimilar materials using a stir welding system.

In recent years, lightweight structures have been increasing in various industrial fields, and in particular, the application of lightweight members has rapidly expanded in the field of transportation machinery (railroad cars, automobiles, ships, aircrafts, etc.).

When fabricating a structure of high strength / light weight material using the conventional melt welding, it was difficult to obtain a satisfactory joint due to the deformation of the welding heat and the welding stress such as residual stress and solidification crack, pore, and oxidation, as well as the strength of the joint.

A new environmentally friendly welding technology that solves this problem, namely, solid-state welding (Friction Stir Welding, FSW) that applies heating and plastic flow by friction, has been disclosed. And it has very low residual stress and it is effective in welding quality and economical because it can obtain high quality joint without generating fume and harmful rays without using filler metal.

In addition, the research subjects are being researched from the existing light alloys of aluminum and aluminum homogeneous to the joining region of the light alloy of dissimilar materials as well as the joining region of the light alloy and steel materials.

However, due to the limitation of the friction stir welding tool material, the material to be joined is limited to a light metal or a low melting point metal, and steel materials have yet to be practically implemented in industrial applications.

In addition, when the friction stir welding tool is inserted into the center of the heterojunction between the light alloy (aluminum alloy) and the steel material (the rolled steel for general structure) by using the conventional friction stir welding technique, the physical properties and the mechanical characteristics are different. It is extremely difficult to bond because an alloy layer vulnerable to the resin is formed, problems such as a decrease in bonding strength and a decrease in plastic stirring occur, and defects occur in the joint.

In addition, when joining light alloys (aluminum alloys) and steel materials (general structural rolled steel) using conventional friction stir welding technology, friction heat generated between the friction stir welding tool and the general structural rolled steel is relatively less than that of aluminum alloy. As a result, it is difficult to reach a sufficient plastic deformation and recrystallization temperature, so that the dropped particles of the general structural rolled steel are dispersed and dispersed toward the aluminum alloy, thereby making it difficult to obtain a healthy joint.

In addition, when joining a steel material (rolling steel for general structure) by using a conventional friction stir welding technique, the wear of the friction stir welding tool is severely generated, and a severe vibration of the friction stir welding device occurs.

In addition, the conventional friction stir welding technique is insufficient to soften the steel material (rolled steel for general structural use) and plastic flow of the dissimilar material joint only by the pressing force and frictional heat of the friction stir welding tool.

The present invention was created in view of the above-described problems in the prior art, and overcomes the limitations of the conventional friction stir welding technology, improves productivity, and obtains excellent bonding characteristics of different materials. In particular, the welding machine is used. In particular, when joining dissimilar materials, preheating steel materials (rolled steel for general structural use) of the dissimilar joints causes sufficient plastic flow due to the rotation and friction of the friction stir welding tool and gives the frictional heat temperature distribution equally. The present invention provides a method for joining dissimilar materials using a hybrid friction stir joining system capable of improving plastic joints and joining properties by softening plastic stir as possible.

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The present invention is a means for achieving the above object, a friction stir welding tool for generating frictional heat while rotating in contact with the joint formed by contacting the rolled steel and aluminum alloy for general structure with each other, and a pre-heating of the joint In a friction stir welding device comprising preheating means, the tag preheating means comprises a teak torch that generates an arc to preheat the joint, a tag welder body that generates a current, an argon, helium or a jet that blows off the tig preheater to protect the atmosphere from the atmosphere. It further includes X, Y, Z axis coordinate setting jig which can set the coordinates according to the position of touching the joint and the preceding position of the tool for friction stir welding as well as having a protective gas which is a mixed gas of argon and helium. To; Most of the pins of the friction stir welding tool are located on the aluminum alloy side, but are installed to be reversely rotated in a state in which only 1 mm or less is disposed on the side of the rolled steel for general structure; The method of preheating the TIG is a method of joining dissimilar materials using a hybrid friction stir welding device which is located on the stainless steel side and located in front of the tool for friction stir welding; The friction stir welding tool is rotated in the reverse direction to generate frictional heat while pressurizing the dissimilar material joint to generate arc from the TIG torch, preheating the rolled steel for general structure in the joint to induce soft nitriding and equal temperature distribution. By suppressing the generation of intermetallic compounds to prevent the falling of fugitive substances from the rolled steel for general structure, the tensile strength of the joint is maintained at an average of 95 to 104% of the tensile strength of the aluminum alloy, Provides a method for joining dissimilar materials using a hybrid friction stir welding system, characterized in that it has a ductile fracture pattern.

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Hybrid friction stir welding system according to the present invention and a heterogeneous material bonding method using the same provides the following effects.

Firstly, when joining different materials of light alloy (aluminum alloy) and steel material (rolling steel for general structure), preheating the TIG to the joint of steel material (rolling steel for general structure) causes friction heat generated by rotation of friction stir welding tool. This may occur together with a sufficient plastic flow of the light alloy (aluminum alloy) and the steel material (rolled steel for general structure) to easily join dissimilar materials.

Second, by performing preheating of the TG, it is possible to improve the plastic stirring of the metal with high hardness and to suppress the weak alloy phase to obtain a healthy joint.

Third, by preheating the TIG to the side of the steel material (rolling steel for general structure), plastic deformation and recrystallization temperature can be reached. It can be effected.

Fourth, it is possible to improve the tensile strength of the dissimilar joints and to suppress the brittle fracture of the joints.

Fifth, there is an effect that can reduce the wear of the friction stir welding tool and improve the productivity by improving the friction stir welding speed.

1 is a block diagram of a heterogeneous material hybrid friction stir welding system according to the present invention.
2 is a side view of a heterogeneous material hybrid friction stir welding system according to the present invention.
3 is an exemplary cross-sectional photograph of a dissimilar material bonded with a dissimilar material hybrid friction stir welding system in accordance with the present invention.
Figure 4 is a graph of the tensile properties of the joints of the joints of the conventional friction stir welding method and the joint of the heterogeneous material hybrid friction stir welding system according to the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

As shown in Figures 1 and 2, the hybrid friction stir welding system 100 according to the present invention is the boundary between the heterogeneous base material, that is, the first and second base materials (101, 102) and the first, second (101, 102) to be joined A friction stir welding tool 104 which abuts and rotates to join, and a tag torch 106 for preheating steel materials (rolled steel for general structural use) of the dissimilar joints.

At this time, the dissimilar base material is in contact with each other to form a joint 103, the first base material 101 is a rolled steel for general structure of steel material, the second base material 102 is preferably made of aluminum alloy of light alloy. .

Here, the heterogeneous base material is not limited to these alloys as described in the preferred embodiment divided into aluminum alloy and rolled steel for general structure, of course, may be made of other light alloy and other steel material.

In addition, the friction stir welding tool 104 is fixed to the spindle 105 of the hybrid friction stir welding system 100 of the present invention, the spindle 105 is connected to the drive shaft of the drive motor 110 to rotate the number of revolutions. Can be set.

On the other hand, the friction stir welding tool 104 is preferably made of cemented carbide with excellent heat resistance and wear resistance and excellent hardness, it is also possible to use other special alloy steel corresponding thereto.

In addition, the friction stir welding tool 104 rotated by the drive motor 110 is inserted into a portion of the second base material 102 that is soft among the joint portions 103 of the dissimilar material and rotates in the reverse direction to generate frictional heat. The bonding is performed in such a manner as to generate and plastic stir the dissimilar material joint.

In addition, the hybrid friction stir welding system 100 according to the present invention includes a TIG preheating system, the TIG torch 106 for generating an arc, the coordinate setting jig 107 which can set the coordinates of the TIG torch 106. And a protective gas for protecting the tag preheating unit from the atmosphere, and a tag welder body generating a current.

At this time, the coordinate setting jig 107 for setting the coordinates of the tag torch includes a gauge that can adjust the distance of the X-axis, Y-axis, Z-axis.

In particular, the X-axis coordinate setting gauge 108 and the Y-axis coordinate setting gauge 109 preferably have a form of setting the coordinates while linearly moving along the guide bar.

In addition, the TIG body may adjust the current according to the thickness and shape of the material, and the protective gas may use any one of argon (Argon), helium (Helium) and a mixed gas of argon and helium according to the bonding conditions.

In addition, the tag body may include a gauge for adjusting the flow rate of the protective gas.

Joining method using the present invention hybrid friction stir welding system consisting of such a configuration is as follows.

First, the second base material 102, which is a light alloy (aluminum alloy), which is a dissimilar base material to be joined, and the first base material 101, which is a steel material (rolled steel for general structural purposes), are disposed to abut each other on a fixing jig.

Then, the pin portion of the friction stir welding tool 104 is positioned on the second base material 102 side, which is mostly a light alloy (aluminum alloy), of the joint portion 103 as shown in FIG. 2, and only about 1 mm of the pin is made of steel material. It is positioned so as to engage in the first base material 101, which is (rolled steel for general structure).

Then, as shown in FIG. 2, the torch 106 to preheat the first base material 101 side is positioned.

At this time, the TIG torch 106 is preferably located at the front of the friction stir welding tool 104.

Thereafter, the friction stir welding tool 104 is brought into contact with the dissimilar material while being rotated in the reverse rotation direction to generate frictional heat, and the torch 106 is preheated to the side of the first base material 101 to form the joint 103 Move along) to create a bond.

As described above, the TIG torch 106 preheats the side of the first base material 101, which is a steel material (rolled steel for general structure), of the dissimilar material joint 103, due to the rotation of the friction stir welding tool 104. Along with the frictional heat generated, the second base material 102 and the first base material 101, which are lightweight alloys (aluminum alloys), easily cause plastic flow, and form an equivalent temperature distribution, thereby joining.

A cross section of the joint of the dissimilar material bonded through the above process has a shape as shown in FIG. 3.

As shown in FIG. 3, it can be seen that according to the present invention, cracks, pores, and intermetallic compounds are hardly generated in the junction 103, and thus, a healthy junction 103 can be obtained.

In addition, when the dissimilar material is bonded through a conventional friction stir welding method, as shown in FIG. 4, the tensile strength of the joint is 6 to 75% of the average tensile strength of the second base material 102 side, which is a light alloy (aluminum alloy). On the other hand, when the composite friction stir welding system (FSW-TIG) of the present invention shows the value, the tensile strength of the joint 103 is excellent as 95 to 104% of the average tensile strength of the second base material 102. It was confirmed that the characteristics were obtained.

In addition, when looking at the tensile failure mode of the dissimilar material joint 103, as shown in Figure 4, the joint according to the conventional method showed a brittle fracture mode, but the joint 103 according to the present invention showed a soft fracture mode It was confirmed that an excellent joint can be obtained through this.

The foregoing has described the preferred embodiments of the present invention, but the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

100: Hybrid friction stir welding system (FSW-TIG)
101: first base material 102: second base material
103 joining portion 104 friction stir welding tool
105: Spindle 106: Tig Torch
107: coordinate setting jig 108: X axis coordinate setting gauge
109: Y-axis coordinate setting gauge 110: drive motor

Claims (8)

delete delete delete delete delete delete delete In a friction stir welding device comprising a friction stir welding tool for generating friction heat while rotating by contacting a joint formed by bringing a rolled steel and an aluminum alloy in contact with each other, and a preheating means for preheating the joint. The preheating means is a protective gas which is either a teak torch that generates an arc to preheat the joint, a body of a welding machine that generates a current, or an argon, helium or a mixed gas of argon and helium that blows off the tig preheater to protect the atmosphere. It further comprises an X, Y, Z axis coordinate setting jig that can of course set the coordinates according to the position of contact with the junction and the preceding position of the friction stir welding tool; Most of the pins of the friction stir welding tool are located on the aluminum alloy side, but are installed to be reversely rotated in a state in which only 1 mm or less is disposed on the side of the rolled steel for general structure; The method of preheating the TIG is a method of joining dissimilar materials using a hybrid friction stir welding device which is located on the stainless steel side and located in front of the tool for friction stir welding;
The friction stir welding tool is rotated in the reverse direction to generate frictional heat while pressurizing the dissimilar material joint to generate arc from the TIG torch, preheating the rolled steel for general structure in the joint to induce soft nitriding and equal temperature distribution. By suppressing the generation of intermetallic compounds while forming a, it is possible to prevent the scattering material from falling out of the rolled steel for general structure,
A method of joining dissimilar materials using a hybrid friction stir welding system, characterized in that the tensile strength of the joint portion maintains an average of 95 to 104% of the tensile strength of the aluminum alloy, and the fracture aspect has a ductile fracture aspect.

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