JP2017170495A - Dissimilar material frictional agitation joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and efficient butting dissimilar material frictional agitation joining method of magnesium or a magnesium alloy material and aluminum or an aluminum alloy material.SOLUTION: In a dissimilar material frictional agitation joining method of magnesium or a magnesium alloy material and aluminum or an aluminum alloy material, the dissimilar material frictional agitation joining method is provided so that a butting surface is formed by respectively arranging magnesium or a magnesium alloy material on the side (the advance side) coincident between the rotational direction and the movement direction of a frictional agitation joining tool and aluminum or an aluminum alloy material on the side (the retreat side) of becoming inverse between the rotational direction and the movement direction, and an insertion position of the frictional agitation joining tool is offset to the magnesium or magnesium alloy material side from the butting surface, and peripheral velocity of a probe part of the frictional agitation joining tool is set to 0.17-0.21 m/s.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a dissimilar friction stir welding method for magnesium or a magnesium alloy material and aluminum or an aluminum alloy material.

  In light of demands for energy saving in various transport equipment, light metal materials are being introduced into structures. Here, magnesium is the lightest metal among practical metals, but applying a magnesium material to all structural members has high hurdles in terms of material strength, cost, etc. The use of multi-material structures combined with materials is eagerly desired.

  Under such circumstances, dissimilar material joining technology is indispensable for manufacturing structures by combining dissimilar materials, but thick metal is present at the joint interface of aluminum / magnesium dissimilar material welds obtained by conventional fusion welding. Since the intermetallic compound layer is formed, it is difficult to obtain a bonded body having sufficient bonding strength and reliability.

  On the other hand, the application of friction stir welding to various dissimilar material joining is being studied. Friction stir welding is a solid phase bonding, and therefore has an advantage that the bonding temperature is lower than that of fusion welding and the formation of intermetallic compounds at the bonding interface can be suppressed.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2003-170280), in the joining method of two kinds of dissimilar metal materials, the melting temperature of the alloy or intermetallic compound produced when the two kinds of metal materials are mixed is the highest. T (L) <T (M), where T (L) is the lower temperature when T (M) is the lower temperature when two kinds of metal materials are friction stir welded together. Dissimilar metal materials characterized by superposing different kinds of metal materials and performing friction stir welding with a welding tool inserted from the low temperature metal material side to the vicinity of the welding interface when the same kind is friction stir welded together. The joining method is disclosed.

  In the joining method described in Patent Document 1, by suppressing the formation of a molten layer, it is possible to prevent the formation of a coarsely solidified structure or a continuous intermetallic compound, and dissimilar metal joining having sufficient joining strength. The body can be obtained efficiently.

  Moreover, in patent document 2 (Unexamined-Japanese-Patent No. 2004-255420), it joins the hard material and the dissimilar metal material which consists of a soft material whose hardness is smaller than the said hard material, and joins a butt surface by friction stir welding. In the method, a pin of a star rod having a hardness ratio with a hard material of 5 or more enters a hard material side with respect to a butt line formed by abutting the hard material and the soft material at least 0.05 mm, Mostly disposed on the soft material side, and the pin is moved in the direction of the butt line while rotating in the direction of movement of the pin from the hard material to the soft material side. A joining method for friction stir welding of materials is disclosed.

  In the joining method described in Patent Document 2, when the steel material and the aluminum material are joined to each other, if the amount of movement of the pin to the hard material side is 0.05 mm or more, the joining portion is more than the aluminum base material. The joining force is large, and in the tensile test, it breaks on the base material side of the aluminum material.

JP 2003-170280 A JP 2004-255420 A

  However, the joining method disclosed in Patent Document 1 is limited to overlap joining. Moreover, the joining method disclosed in Patent Document 2 is a method for joining different materials having different melting points and mechanical properties. Here, in addition to the difference in melting point between magnesium and aluminum being about 10 ° C., a brittle intermetallic compound layer is formed at the bonding interface by a eutectic reaction at a low temperature. The joining method cannot be applied.

  SUMMARY OF THE INVENTION In view of the problems in the prior art as described above, an object of the present invention is to provide a simple and efficient butt dissimilar material friction stir welding method for magnesium or magnesium alloy material and aluminum or aluminum alloy material.

  As a result of intensive studies on the relationship between friction stir welding conditions and joint strength, etc., in order to achieve the above object, the present inventors have found that there is a numerical range suitable for the peripheral speed of the probe portion of the friction stir welding tool, etc. And reached the present invention.

That is, the present invention
A different material friction stir welding method between magnesium or magnesium alloy material and aluminum or aluminum alloy material,
The magnesium or magnesium alloy material is on the side where the rotational direction and the moving direction of the friction stir welding tool coincide (forward side), and the aluminum or aluminum alloy on the side where the rotational direction and the moving direction are opposite (reverse side) Each material is arranged to form a butt surface,
The insertion position of the friction stir welding tool is offset from the butt surface to the magnesium or magnesium alloy material side,
The peripheral speed of the probe portion of the friction stir welding tool is 0.17 to 0.21 m / s,
A dissimilar material friction stir welding method is provided.

  It is known that the amount of heat generated during friction stir welding increases on the forward side under general appropriate welding conditions. Here, by arranging magnesium or a magnesium alloy material having a lower friction coefficient with the friction stir welding tool than aluminum or an aluminum alloy material on the forward side, the heat input amount of the entire stirring unit can be suppressed. As a result, formation of an intermetallic compound layer at the bonding interface is suppressed, and appropriate friction stir welding conditions can be expanded.

  When the same kind of materials to be joined are friction stir welded, a friction stir welding tool is inserted into the materials to be joined so that the center of the probe portion coincides with the abutting surface (hereinafter referred to as the 0 position). In contrast, in the dissimilar material friction stir welding method of the present invention, the friction stir welding tool is offset from the 0 position to the magnesium or magnesium alloy side, and the amount of insertion of the probe portion into the magnesium or magnesium alloy material is increased.

  Aluminum or an aluminum alloy material has a face-centered cubic lattice structure, and thus has a lot of sliding system and high fluidity. However, since magnesium or a magnesium alloy material has a hexagonal close-packed structure, the sliding system is small and fluidity is poor. Therefore, in the dissimilar material friction stir welding method of the present invention, the friction stir welding tool is offset from the 0 position to the magnesium or magnesium material side to promote the material flow of the magnesium material.

  Moreover, in the dissimilar material friction stir welding method of this invention, the peripheral speed of the probe part of the said tool for friction stir welding is 0.17-0.21 m / s. By setting the peripheral speed of the probe part to 0.17 m / s or more, the material fluidity can be secured and the formation of defects in the stirring part can be suppressed. On the other hand, by setting the peripheral speed of the probe portion to 0.21 m / s or less, it is possible to prevent the intermetallic compound layer at the bonding interface from becoming thick due to excessive heat input.

  As one of the process parameters of friction stir welding, the rotational speed of a friction stir welding tool is generally used. Here, even if the rotation speed is the same, the peripheral speed varies depending on the diameter of the probe part, but good frictional stirring with different materials can be achieved by setting the peripheral speed to 0.17 to 0.21 m / s regardless of the diameter of the probe part. A joint joint can be obtained.

  Moreover, in the dissimilar material friction stir welding method of this invention, it is preferable that the said peripheral speed shall be 0.17-0.19 m / s. By setting the peripheral speed of the probe portion to 0.19 m / s or less, it is possible to more reliably prevent the intermetallic compound layer at the bonding interface from becoming thick due to excessive heat input.

  In the dissimilar material friction stir welding method of the present invention, it is preferable that the offset moving distance is 0.5 to 1.5 mm. By making the amount of offset movement 0.5 mm or more, the material flow of magnesium or magnesium material can be sufficiently promoted, and by setting it to 1.5 mm or less, the material fluidity of aluminum or aluminum material is reduced. Can be suppressed.

  Furthermore, in the dissimilar material friction stir welding method of the present invention, it is preferable that the diameter of the probe portion is 3 to 5 mm. By setting the diameter of the probe portion to 3 mm or more, the strength of the probe portion can be ensured, and by setting it to 5 mm or less, formation of defects in the stirring portion can be suppressed (when the probe becomes thick, the probe passes through). It is difficult to refill the space formed by the material flow).

  According to the present invention, a simple and efficient butt dissimilar material friction stir welding method between magnesium or a magnesium alloy material and aluminum or an aluminum alloy material can be provided.

It is the schematic which shows arrangement | positioning of the to-be-joined material at the time of friction stirring. It is the schematic which shows an example of the tool for friction stir welding used by this invention. It is the schematic which shows the positional relationship of a to-be-joined material and the tool for friction stir welding. It is a graph which shows the tensile strength of a dissimilar material friction stir welding joint (relationship between peripheral speed and joining strength). It is a graph which shows the tensile strength of a dissimilar material friction stir welding joint (relationship between arrangement | positioning of to-be-joined material, and joining strength). It is the surface appearance of a dissimilar material friction stir welding joint. It is a cross-sectional macro photograph of a dissimilar material friction stir welded joint. It is SEM-EDS element mapping of the joining interface vicinity.

  Hereinafter, representative embodiments of the dissimilar material friction stir welding method of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description may be omitted. Further, since the drawings are for conceptually explaining the present invention, the dimensions and ratios of the components shown may be different from the actual ones.

  FIG. 1 is a schematic view showing an arrangement of materials to be joined at the time of friction stir welding. A bonded interface 6 is formed by abutting aluminum or an aluminum alloy material 2 and magnesium or a magnesium alloy material 4 on the material to be bonded. Here, the friction stir welding of different materials is achieved by inserting and moving the friction stir welding tool 8 shown in FIG.

  Friction stir welding is referred to as FSW (Friction Stir Welding), where the ends of the materials to be joined made of two metal materials to be joined are abutted, and the protrusion (probe) provided at the tip of the rotary tool is attached to both of them. It is a method of joining two metal members by inserting between the end portions and moving the rotary tool along the longitudinal direction of these end portions while rotating.

  Here, in the dissimilar material friction stir welding of the present invention, the magnesium or magnesium alloy material 4 is placed on the side where the rotational direction and the moving direction of the friction stir welding tool 8 coincide (the forward side), and the rotational direction and the moving direction are reversed. Aluminum or aluminum alloy material 2 is arranged on each side (retreat side). By disposing the magnesium or magnesium alloy material 4 having a lower coefficient of friction with the friction stir welding tool 8 compared to the aluminum or aluminum alloy material 2 on the forward side, the heat input amount of the entire stirring unit can be suppressed. As a result, formation of an intermetallic compound layer at the bonding interface is suppressed, and appropriate friction stir welding conditions can be expanded.

  The shape of the friction stir welding tool 8 is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known shapes can be used. Generally, the probe portion 12 is provided on the bottom surface of the tool main body portion 10. Is equipped. With respect to the shape of the probe portion 12, it is possible to prevent breakage of the probe portion 12 during friction stir welding by making the base thick and tapered, but in the dissimilar material friction stir welding of the present invention, It is preferable to do. By making the probe part 12 cylindrical, a homogeneous stirring region can be formed in the plate thickness direction. In addition, the stirring effect can be promoted by forming a screw in the probe portion 12.

  The diameter of the probe portion 12 may be appropriately set according to the thickness of the material to be joined, but is preferably 3 to 5 mm. By setting the diameter of the probe portion 12 to 3 mm or more, the strength of the probe portion 12 can be ensured, and by setting the diameter to 5 mm or less, formation of defects in the stirring portion can be suppressed (if the probe portion 12 becomes thicker, the probe It is difficult to refill the space formed by the passage of the portion 12 by material flow).

  Further, the material of the friction stir welding tool 8 is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known materials can be used. For example, tool steel, cemented carbide, ceramics, and the like are used. be able to.

  Further, in the dissimilar material friction stir welding method of the present invention, the insertion position of the friction stir welding tool 8 is offset from the butt surface (bonded interface 6) to the magnesium or magnesium alloy material 4 side. When friction stir welding is performed on the same kind of materials to be welded, the friction stir welding tool 8 is inserted so that the center of the probe portion 12 coincides with the interface 6 to be welded. By offsetting the joining tool 8 from the 0 position to the magnesium or magnesium alloy material 4 side, the insertion amount of the probe portion 12 into the magnesium or magnesium alloy material 4 is increased.

  The offset amount a of the friction stir welding tool 8 may be appropriately set according to the shape of the friction stir welding tool 8 to be used, the thickness of the material to be joined, and the like, for example, 0.5 to 1.5 mm. Is preferred. The material flow of the magnesium or magnesium alloy material 4 can be sufficiently promoted by setting the offset amount a to 0.5 mm or more, and the material fluidity of the aluminum or aluminum material 2 can be reduced by setting the offset amount a to 1.5 mm or less. Can be suppressed.

  In the dissimilar material friction stir welding of the present invention, the peripheral speed of the probe portion 12 of the friction stir welding tool 8 is set to 0.17 to 0.21 m / s. By setting the peripheral speed of the probe part 12 to 0.17 m / s or more, the material fluidity can be secured and the formation of defects in the stirring part can be suppressed. On the other hand, by setting the peripheral speed of the probe portion 12 to 0.21 m / s or less, it is possible to prevent the intermetallic compound layer at the bonding interface from becoming thick due to excessive heat input.

  Here, even if the rotation speed is the same, the peripheral speed is different depending on the diameter of the probe portion 12, but the peripheral speed is 0.17 to 0.21 m / s regardless of the diameter of the probe portion 12, which is favorable. A dissimilar material friction stir welded joint can be obtained.

  Here, the peripheral speed is preferably 0.17 to 0.19 m / s. By setting the peripheral speed of the probe portion 12 to 0.19 m / s or less, it is possible to more reliably prevent the intermetallic compound layer from becoming thick at the joint interface due to excessive heat input.

  The aluminum or aluminum alloy material 2 is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known aluminum or aluminum alloy materials can be used. Further, the magnesium or the magnesium alloy material 4 is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known magnesium or magnesium alloy materials can be used.

  As mentioned above, although typical embodiment of this invention was described, this invention is not limited only to these, Various design changes are possible and these design changes are all contained in the technical scope of this invention. It is.

Example 1
In the arrangement shown in FIG. 3, JIS-A6N01 aluminum alloy plate (3 mm × 100 mm × 330 mm) and JIS-AZ31 magnesium alloy plate (3 mm × 100 mm × 330 mm) are butted and a friction stir welding tool is inserted into the butted surface. Dissimilar material friction stir welding was performed. The JIS-A6N01 aluminum alloy sheet is disposed on the retreat side, and the JIS-AZ31 magnesium alloy sheet is disposed on the advance side. Tables 1 and 2 show the compositions of the JIS-A6N01 aluminum alloy sheet and the JIS-AZ31 magnesium alloy sheet, respectively.

  The friction stir welding tool is made of tool steel and has a shoulder diameter of 10 mm, a probe diameter of 3 mm (with a screw and no taper), and a probe length of 2.9 mm. The center of the probe is offset by 1 mm from the abutting surface toward the JIS-AZ31 magnesium alloy plate, and wire bonding is performed with the rotational speed and moving speed of the friction stir welding tool set to 1100 rpm and 50 mm / min, respectively, to obtain a different material friction stir welded joint. It was. The peripheral speed of the probe part is 0.172 m / s.

  A tensile test piece (JIS Z2241 14B test piece) was cut out from the obtained dissimilar friction stir welded joint, and a tensile test was performed at a crosshead speed of 2.4 mm / min using a tensile tester (SHIMADZU Autograph AGS-X 10 kN). went. Note that the tensile test piece was cut out in the direction perpendicular to the joining direction so that the joining interface was approximately the center in the longitudinal direction of the test piece. The obtained tensile strength is shown in FIG.

<< Example 2 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the rotation speed was 1200 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.188 m / s.

Example 3
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the rotation speed was 1300 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.204 m / s.

Example 4
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 4 mm and the rotation speed was 900 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.188 m / s.

Example 5
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 4 mm and the rotation speed was 1000 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.209 m / s.

Example 6
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 5 mm and the rotation speed was 700 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.183 m / s.

Example 7
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 5 mm and the rotation speed was 800 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.209 m / s.

≪Comparative example 1≫
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the rotation speed was 900 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.141 m / s.

≪Comparative example 2≫
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the rotation speed was 1000 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.157 m / s.

«Comparative Example 3»
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the rotation speed was 1500 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.236 m / s.

<< Comparative Example 4 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 4 mm and the rotation speed was 800 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.167 m / s.

<< Comparative Example 5 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 4 mm and the rotation speed was 1100 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.230 m / s.

<< Comparative Example 6 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 5 mm and the rotation speed was 600 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.157 m / s.

<< Comparative Example 7 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the probe diameter was 5 mm and the rotation speed was 900 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.236 m / s.

«Comparative Example 8»
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the JIS-A6N01 aluminum alloy sheet was placed on the forward side, the JIS-AZ31 magnesium alloy sheet was placed on the backward side, and the rotational speed was 900 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. 5 (The tensile strength obtained in Examples 1-3 and Comparative Examples 1-3 is also shown as reference). . The peripheral speed of the probe part is 0.141 m / s.

<< Comparative Example 9 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the JIS-A6N01 aluminum alloy sheet was disposed on the forward side and the JIS-AZ31 magnesium alloy sheet was disposed on the backward side. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.172 m / s.

<< Comparative Example 10 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the JIS-A6N01 aluminum alloy sheet was placed on the forward side, the JIS-AZ31 magnesium alloy sheet was placed on the backward side, and the rotational speed was 1200 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.188 m / s.

<< Comparative Example 11 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the JIS-A6N01 aluminum alloy sheet was placed on the forward side, the JIS-AZ31 magnesium alloy sheet was placed on the backward side, and the rotational speed was 1300 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.204 m / s.

<< Comparative Example 12 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the JIS-A6N01 aluminum alloy sheet was placed on the forward side, the JIS-AZ31 magnesium alloy sheet was placed on the backward side, and the rotational speed was 1400 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.220 m / s.

<< Comparative Example 13 >>
A dissimilar material friction stir welded joint was obtained in the same manner as in Example 1 except that the JIS-A6N01 aluminum alloy sheet was placed on the forward side, the JIS-AZ31 magnesium alloy sheet was placed on the backward side, and the rotational speed was 1500 rpm. Moreover, the tensile test was done like Example 1 and the obtained tensile strength was shown in FIG. The peripheral speed of the probe part is 0.236 m / s.

  In FIG. 4, good tensile strength of 100 MPa or more is obtained in all of Examples 1 to 7 in which the peripheral speed of the probe portion is 0.17 to 0.21 m / s. Further, Examples 1, 2 and 4 in which the peripheral speed of the probe portion is in the range of 0.17 to 0.19 m / s show particularly high tensile strength.

  In FIG. 5, it can be seen that by arranging the JIS-A6N01 aluminum alloy sheet on the backward side and the JIS-AZ31 magnesium alloy sheet on the forward side, the tensile strength increases regardless of the rotational speed of the tool.

  The surface appearance of the dissimilar material friction stir welded joint obtained in Example 1 and Comparative Example 9 is shown in FIG. Even when the welding conditions such as the rotational speed and moving speed of the tool are the same, the surface state varies greatly depending on the arrangement of the materials to be joined. The JIS-A6N01 aluminum alloy sheet is moved backward, the JIS-AZ31 magnesium alloy sheet is It can be seen that a smooth joint surface can be obtained by disposing on the forward side.

  A cross-sectional macro photograph of the dissimilar material friction stir welded joint obtained in Example 1 is shown in FIG. It can be confirmed that no defects were found in the stirring portion and a good joint was obtained.

  In order to confirm the state of the joint interface and the like regarding the dissimilar material friction stir welded joint obtained in Example 1 and Comparative Example 3, the cross section of the joint was observed in detail by SEM-EDS (JEOL JSM-7001FA). The conditions for SEM observation were acceleration voltage: 15 kV and irradiation current: 10A. A cross section polisher (JEOL IB-09020CP) that uses a argon ion beam and a shielding plate to polish the sample cross section was used for the preparation of the cross section sample for SEM observation.

  The result of SEM-EDS element mapping in the vicinity of the bonding interface is shown in FIG. In the dissimilar material friction stir welded joint obtained in Example 1, the JIS-A6N01 aluminum alloy plate and the JIS-AZ31 magnesium alloy plate are joined through an extremely thin reaction layer. On the other hand, in the dissimilar friction stir welded joint obtained in Comparative Example 3 in which the peripheral speed of the probe part is faster than 0.21 m / s, the thickness of the reaction layer is remarkably increased to about 5 μm. I understand.

  In addition, a different material friction stir welded joint was formed in the same manner as in Example 4 except that the offset amount of the tool was 2 mm, 0 mm on the JIS-AZ31 magnesium alloy plate material side, or 1 mm on the JIS-A6N01 aluminum alloy plate material side. When a tensile test was conducted in the same manner as in Example 1, when the thickness was 2 mm on the JIS-AZ31 magnesium alloy sheet side and 1 mm on the JIS-A6N01 aluminum alloy sheet side, the bonding strength was low and an accurate value was obtained. It was difficult. Further, in the case of 0 mm, the strength was reduced by about 20% compared to the case of Example 4.

2 ... aluminum or aluminum alloy material,
4 ... Magnesium or magnesium alloy material,
6: Bonded interface,
8 ... Tool for friction stir welding,
10 ... Tool body,
12: Probe portion.

Claims (4)

A different material friction stir welding method between magnesium or magnesium alloy material and aluminum or aluminum alloy material,
The magnesium or magnesium alloy material is on the side where the rotational direction and the moving direction of the friction stir welding tool coincide (forward side), and the aluminum or aluminum alloy on the side where the rotational direction and the moving direction are opposite (reverse side) Each material is arranged to form a butt surface,
The insertion position of the friction stir welding tool is offset from the butt surface to the magnesium or magnesium alloy material side,
The peripheral speed of the probe portion of the friction stir welding tool is 0.17 to 0.21 m / s,
Dissimilar material friction stir welding method characterized by the above. The peripheral speed is 0.17 to 0.19 m / s,
The dissimilar material friction stir welding method according to claim 1. The movement distance of the offset is 0.5 to 1.5 mm,
The dissimilar material friction stir welding method according to claim 1 or 2. The diameter of the probe is 3 to 5 mm;
The dissimilar material friction stir welding method according to any one of claims 1 to 3.