JP4372625B2 - Friction stir welding method for metal member and metal joint - Google Patents

Description

  The present invention relates to a friction stir welding method for a metal member in which a metal plate member is superposed on an outer peripheral surface of a metal bar member and friction stir welding is performed, and further relates to a metal joint manufactured by the method.

  The friction stir welding method is a type of solid-phase joining in which the metal at the joint is plastically flowed by the stirring heat generated by the rotation of the welding tool and joined by cooling and solidification. There is an advantage that it is difficult to cause deformation and cracking. For this reason, it is applied to manufacture of various metal joints such as aluminum (see Patent Documents 1, 2, and 3).

  FIG. 9 shows a manufacturing example of the joint (22) in which the cylindrical tube (1) and the plate-like member (2) are joined.

In FIG. 9, the cylindrical tube (1) is fitted into the mounting recess (3) having an arc cross section in the plate-like member (2), and the plate-like member (2) is overlapped on the outer peripheral surface of the cylindrical tube (1). Both members (1) and (2) are temporarily assembled in the state. In this temporarily assembled state, the outer peripheral surface of the cylindrical tube (1) and the mounting recess (3) of the plate-like member (2) are in surface contact. Then, as shown in FIG. 1, from the plate-like member (2) side, the probe (11) protruding from the axial center of the welding tool (10) is inserted into the starting end of the bonding line, and the tip surface (12) is positioned at a depth that reaches the cylindrical tube (1), and is relatively moved along the longitudinal direction of the cylindrical tube (1). As a result, the material of both members (1) and (2) is plastically flowed by frictional heat and pressure, and after passing through the probe (11), it loses frictional heat and rapidly cools and solidifies, and both members (1) and (2) Are joined in a state in which the material metals are stirred and integrated. In the production of this joint (22), the joining line is on the center line (P) of the cylindrical tube (1) and the ceiling part of the mounting recess (3) of the plate-like member (2) (the thinnest part) The probe (11) is inserted toward the center of the cylindrical tube (1).
JP 2003-31444 A Japanese Patent Laid-Open No. 2003-1440 JP 2002-153976 A

  The joints described above are widely used as vehicle structural materials and the like, and further improvement in joint strength is desired. If the joint line is extended, the joint strength is improved, but there is a problem that it takes a long time to join. In addition, if it is necessary to increase the size of the plate-like member in order to ensure a long joint line, problems such as an increase in material costs and interference with other members due to the increase in size of the plate-like member arise.

  In view of the background art described above, the present invention is intended to improve joint strength without an extension of the joining line or an increase in the size of the member when producing a lap joint of a rod-like member such as a cylindrical tube and a plate-like member. It is an object of the present invention to provide a friction stir welding method for metal members that can be manufactured, and to provide a metal joint joined by the method.

  That is, the friction stir welding method for metal members of the present invention has the configurations described in [1] to [13] below.

  [1] When the friction stir welding is performed in the surface contact region where the metal plate member (B) is superimposed on the outer peripheral surface of the metal rod member (A), the probe of the friction stir welding tool is disposed at the tip of the plate. The member (B) is inserted to a depth that penetrates in the thickness direction and reaches the rod-like member (A), and the tip end surface of the probe is inserted into the rod-like member (A) and the plate-like member (B) in the inserted state. In this inserted state of the probe, the two members (A) and (B) are frictionally agitated by moving the joining tool relative to each other in the length direction while rotating the joining tool. A friction stir welding method for metal members, characterized by joining.

  [2] Friction of the metal member according to [1], wherein the probe is positioned so that one side portion of the outer peripheral edge of the tip surface protrudes from the contact interface of the surface contact region and faces the plate-like member (B). Stir welding method.

  [3] The probe is positioned so that both side portions symmetrically positioned on the left and right of the outer peripheral edge of the tip surface protrude from the contact interface of the surface contact region and face the plate-like member (B). Friction stir welding method for metal members.

  [4] Any of [1] to [3], wherein an amount of protrusion of the outer peripheral edge of the tip surface to the plate-like member (B) side at the time of insertion of the probe is set to 35% or less of the tip surface diameter of the probe. 2. A friction stir welding method for metal members according to item 1.

  [5] The friction stir welding method for metal members according to [4], wherein the amount of protrusion is set to 5 to 30% of the diameter of the tip surface of the probe.

  [6] An assembly recess corresponding to the outer peripheral surface of the rod member (A) is formed on one surface of the plate member (B), and a part of the rod member (A) is formed in the assembly recess. The friction stir welding method for metal members according to any one of [1] to [5], wherein the surface contact regions of both members (A) and (B) are formed by being fitted together.

  [7] The metal member friction stir welding method according to [6], wherein the rod-shaped member (A) is a rod-shaped member having a circular cross section, and the mounting recess of the plate-shaped member (B) is an arc-shaped recess.

  [8] The rod-shaped member (A) is a rod-shaped member having a polygonal cross section, and the mounting recess of the plate-shaped member (B) is an area including one or a plurality of ridge corners of the rod-shaped member (A). [6] The friction stir welding method for metal members according to [6], which is a rectangular recess corresponding to the outer peripheral surface.

  [9] The friction stir welding method for metal members according to any one of [1] to [8], wherein the rod-shaped member (A) is a hollow or solid rod-shaped member.

  [10] The plate-like member (B) has the mounting recess formed at one end thereof, and the other end protrudes to the side of the rod-like member (A) when assembled with the rod-shaped member (A). The friction stir welding method for metal members according to any one of [6] to [9], wherein the friction stir welding method is used.

  [11] The metal member friction stirrer according to any one of [1] to [10], wherein the probe insertion position is set to a position offset by a predetermined distance laterally from the center of the rod-shaped member (A). Joining method.

  [12] The friction stir welding method for metal members according to [11], wherein the offset direction is set to the direction of the other end protruding from the rod-like member of the plate-like member (B).

  [13] The friction stir welding method for metal members according to any one of [1] to [12], wherein at least one of the rod-like member (A) or the plate-like member (B) is made of aluminum or an aluminum alloy.

  Moreover, the metal joint of this invention has the structure as described in following [14]-[16].

  [14] The metal rod-like member (A) and the metal plate-like member (B) are joined by the metal member friction stir welding method described in any one of [1] to [13], and the rod-like member ( A metal joint comprising a stirring joint formed along the length direction of A).

  [15] The metal joint according to [14], wherein the metal joint is a structural metal part.

  [16] The metal joint according to [15], wherein the structural metal component is a vehicle metal component.

  According to the friction stir welding method for metal members according to the invention of [1], a high joint strength is obtained by positioning the tip end surface of the probe so as to straddle the rod-like member (A) and the plate-like member (B). be able to. And it can implement, without extending a joining line or enlarging a member.

  According to the friction stir welding method for metal members according to the invention [2], high bonding strength can be obtained without extending the joining line or expanding the members.

  According to the friction stir welding method for metal members according to the invention of [3], high joint strength can be obtained without extending the joining line or expanding the members.

  According to the invention [4], particularly high bonding strength can be obtained.

  According to the invention of [5], higher strength can be obtained.

  According to the invention [6], the assembled state of the rod-like member (A) and the plate-like member (B) is stable, and a wide surface contact region can be obtained and stable joining can be performed.

  According to the invention of [7], the assembled state of the rod-like member (A) having a circular cross section and the plate-like member (B) is stable, and a wide surface contact region can be obtained and stable joining can be performed.

  According to the invention of [8], the assembled state of the rod-like member (A) having a polygonal cross section and the plate-like member (B) is stable, and a wide surface contact region can be obtained and stable joining can be performed. .

  According to the invention [9], high joining strength can be obtained in joining the hollow or solid rod-like member (A) and the plate-like member (B).

  According to the invention of [10], high joining strength can be obtained in joining using the plate-like member (B) protruding to the side of the rod-like member (A) in the assembled state.

  According to the invention [11], the tip end surface of the probe can be positioned so as to straddle the rod-like member (A) and the plate-like member (B) only by changing the insertion position of the probe.

  According to the invention [12], particularly high bonding strength can be obtained in the bonding using the plate-like member (B) protruding to the side of the rod-like member (A) in the assembled state.

  According to the invention of [13], a metal joint made of aluminum or an aluminum alloy can be manufactured.

  The metal joint according to the invention [14] has a high joint strength because the rod-like member (A) and the plate-like member (B) are joined by the friction stir welding method.

  According to the invention of [15], the metal part for structural material having high bonding strength can be obtained.

  According to the invention of [16], it can be a metal part for a structural material of a vehicle having a high bonding strength.

The friction stir welding method for metal members of the present invention will be described below along with the production of several types of metal joints.
[First Embodiment]
In the present embodiment, description will be given by taking as an example the manufacture of a metal joint in which a metal plate-like member is joined to the outer peripheral surface of a metal cylindrical tube having a circular cross section.

  1 and 2, the cylindrical tube (1) has a circular cross section and corresponds to the rod-shaped member (A) in the present invention. The plate-like member (2) corresponds to the plate-like member (B) in the present invention, and has a circular arc cross section corresponding to the outer peripheral surface of the cylindrical tube (1) on one surface side of one end in the width direction. The assembling recess (3) is formed, and the other end is a flat flange portion (4).

  As a preparatory stage for joining, the cylindrical tube (1) is fitted into the assembly recess (3) of the plate-like member (2) and overlapped, and the outer peripheral surface of the cylindrical tube (1) and the plate-like member (2) are overlapped. Temporarily assembled in a state where the peripheral surface of the mounting recess (3) is in surface contact. In this assembled state, the flange portion (4) of the plate-like member (2) protrudes to the side of the cylindrical tube (1).

After the temporary assembly, the probe (11) of the friction stir welding tool (10) is inserted from the plate-like member (2) side to perform friction stir welding. The probe (11) is inserted in the thickness direction of the plate-like member (2), and is inserted to a depth where the tip portion penetrates the plate-like member (2) and reaches into the cylindrical tube (1). At this time, the distal end surface (12) of the probe (11) is positioned so as to straddle the cylindrical tube (1) and the plate member (2). In the present embodiment shown in FIG. 2, the probe (11) is inserted at a position offset by a predetermined distance (X1) from the center line (P) of the cylindrical tube (1) toward the flange portion (4). 11) One end portion (Y1) of the outer peripheral edge of the front end surface (12) is positioned so as to protrude from the contact interface of the surface contact region and face the plate-like member (2). That is, in the cross-sectional view (FIG. 2) along the insertion direction of the probe (11), one side (Y1) of the distal end surface (12) faces into the plate-like member (2) due to the offset of the insertion position. The other side portion (Y2) positioned symmetrically is positioned so as to face the cylindrical tube (1). (X2) in the figure indicates the amount of protrusion from the bonding interface of one side (Y1). In the inserted state of the probe (11), when the welding tool (10) is rotated and relatively moved in the length direction of the cylindrical tube (1), the material metal in the vicinity of the probe (11) is successively rubbed. Softened by heat and stirred. Then, when the material metal is cooled and solidified after passing through the probe (11), the cylindrical tube (1) and the plate-like member (2) are formed along the length direction of the cylindrical tube (1). ) To produce the metal joint (20).
[Second Embodiment]
In the present embodiment, description will be given by taking as an example the production of a metal joint in which a metal plate-like member is joined to the outer peripheral surface of a metal round bar.

  In FIG. 3, a round bar (6) is a solid material having a circular cross section, and corresponds to the bar-like member (A) in the present invention. The plate-like member (7) corresponds to the plate-like member (B) in the present invention, and has an arcuate assembling recess corresponding to the outer peripheral surface of the round bar (6) at the center in the width direction. (8) is formed, and flat flange portions (9) are formed at both ends.

As shown in FIG. 3, the probe (13) used in this embodiment has a larger diameter than the probe (11). Then, in the temporarily assembled state of the round bar (6) and the plate-like member (7), the probe (13) is inserted to a predetermined depth from the plate-like member (7) side on the center line (P) of the round bar (6). And it positions so that the front end surface (14) may straddle a round bar (6) and a plate-shaped member (7). That is, in the cross-sectional view (FIG. 3) along the insertion direction of the probe (13), both sides (Y1) (Y2) located symmetrically on the outer peripheral edge of the tip surface (14) are plate-like members (6). It is positioned so as to face the inside and face the round bar (6) at the center. (X2) in the figure indicates the amount of protrusion from the joint interface of both side portions (Y1) (Y2). Then, in the inserted state of the probe (13), when the tool (10) is rotated and relatively moved in the length direction of the round bar (6), the round bar (6) and the plate-like member (7) Are joined by a friction stirrer (not shown) formed along the length of the round bar (6) to produce a metal joint (21).
[Third Embodiment]
This embodiment is a friction stir welding between a rod-like member having a square cross section and a plate-like member. In addition, in the following description, what was shown with the code | symbol in FIGS. 1-3 is abbreviate | omitted description which shows the thing equivalent to these.

  The square bar (31) illustrated in FIG. 4 is a solid material having a square cross section. On the other hand, on one surface side of the one end portion of the plate-like member (32), a rectangular assembly recess (33) corresponding to the outer peripheral surface shape of the region including the ridge corner portion of the square bar (31) is formed. A flat flange portion (34) is formed at the end. Both members (31) and (32) are temporarily assembled by fitting square bars (31) into the mounting recesses (33) of the plate-like member (32).

  Then, by inserting the probe (11) at a position offset from the center line (P) of the square member (31) to the flange portion (34) side, one side portion (Y1) of the outer peripheral edge of the distal end surface (12) is formed. Friction stir welding is performed with the other side portion (Y2) facing the square bar (31), protruding from the joining interface and facing the plate-like member (32).

  The square bar (41) illustrated in FIG. 5 is a solid material having an octagonal cross section. On the other hand, a polygonal mounting recess (43) corresponding to the shape of the outer peripheral surface of the region including the two ridge corners of the square bar (41) is formed on one surface side of one end of the plate-like member (42). A flat flange portion (44) is formed at the other end. Both members (41) and (42) are temporarily assembled by fitting square bars (41) into the mounting recesses (43) of the plate-like member (34).

  Then, the probe (11) is inserted into a position offset from the center line (P) of the square bar (41) toward the flange portion (44), so that one side portion (Y1) of the outer peripheral edge of the distal end surface (12) Protrudes from the joining interface and faces the plate-like member (42), and the other side portion (Y2) is friction stir welded in a state facing the square bar (41).

  The square bars (31) and (41) correspond to the bar-shaped member (A) in the present invention, and the plate-shaped members (32) and (42) correspond to the plate-shaped member (B) in the present invention.

  The friction stir welding method of the present invention can be applied to all metal materials that can be friction stir welded, including aluminum, copper, iron, and alloys thereof, and may be joints of similar metal members or dissimilar metal members. It doesn't matter. In particular, it can be recommended for joining metal members made of aluminum or aluminum alloys that are lightweight and have high strength and are used as various structural materials.

  The shape of the rod-shaped member (A) is not limited and can be applied to both a hollow material and a solid material. Moreover, it is not limited to the cross-sectional circle and polygonal cross-section of the said embodiment, An irregular cross-sectional shape may be sufficient.

  Further, the plate-like member (B) is not limited as long as it can be assembled in a state where it is overlapped with the rod-like member. However, by using a plate-like member in which a recess for assembly as shown in the above embodiment is used, the assembly state with the rod-like member is stable, and a wide surface contact area is obtained to perform stable joining. be able to. Moreover, the shape of the portion corresponding to the flange portions (4), (9), (34), and (44) of the above embodiment is not limited to the simple flat plate shape shown in the above embodiment. Furthermore, the present invention also includes a joint using a plate-like member having no flange portion regardless of the presence or absence of the flange portion protruding to the side.

  In the friction stir method of the present invention, high joint strength can be obtained by positioning the tip end surface of the probe so as to straddle the rod-like member (A) and the plate-like member (B). This is presumed to be due to the fact that the two metal materials are well stirred and the uniform friction stirrer is formed rather than the entire tip surface being present in the rod-shaped member.

  If the amount of protrusion (X2) of the probe tip surface to the plate-like member is set excessively large, the stirring region in the rod-like member (A) may be narrowed and the bonding strength may be reduced. (12) It is preferably set to 35% or less of the diameter. A particularly preferred amount of protrusion (X2) is 5 to 30%. Moreover, when both sides of the outer peripheral edge of the probe (13) tip surface (14) protrude as in the second embodiment, the left and right protrusion amounts (X2) are each preferably 35% or less.

  The straddling of the probe tip surface to both members (A) and (B) is achieved by, for example, offset of the probe insertion position as in the first and third embodiments, or a probe having a large diameter as in the second embodiment. Is achieved by using In addition, when the cross-sectional shape of the rod-shaped member (A) is asymmetric with respect to the center line (P), one side portion of the probe tip surface is a plate-shaped member (even if inserted on the center line (P)). A) faces inside and the other side faces the rod-like member (B), and is positioned so as to straddle both members (A) and (B) without necessarily depending on the offset.

  Moreover, when the flange part of a plate-shaped member (B) protrudes from the side of a rod-shaped member (A) at the time of an assembly | attachment, it is preferable to set an offset direction to the flange part side. This is because in such a joint, a load is often input to the flange portion, and higher strength can be secured.

  Since the metal joint manufactured by the present invention has high joint strength, it can be suitably used as various metal parts for structural materials, for example, metal parts for structural members of vehicles. Moreover, in order to implement the joining method of this invention, the change of the shape of a rod-shaped member (A) and a plate-shaped member (B) and an enlargement are not accompanied, but a conventional member can be used continuously. For this reason, even when arrange | positioning the coupling of this invention with another member, it does not interfere with another member.

  A joint (20) shown in FIGS. 1 and 2 was manufactured using the cylindrical tube (1) and the plate-like member (2) shown in FIG.

  Both the cylindrical tube (1) and the plate member (2) are made of JIS A6061-T6. The cylindrical tube (1) has an outer diameter (D1): 26 mm, a wall thickness (T1): 4 mm, and a length (L1): 150 mm. The plate-like member (2) has a width (W): 43 mm, a length (L2): 70 mm, a curvature radius (R) of the mounting recess (3) having an arcuate cross section: 13 mm, and a circumferential surface length (L3, Peripheral length of contact with the cylindrical tube): 23.9 mm, the thickness (T2) of the ceiling portion of the mounting recess (3): 2 mm, and the thickness (T3) of the flange portion (4): 3 mm. Further, the welding tool (10) used for the friction stir welding has a shoulder diameter (D2) of 10 mm, a diameter of the probe (11) (D3): 4 mm, and a length of the probe (11) (L4): 3.5 mm. It is.

  Then, as shown in FIGS. 2 and 7, a plate-like member (2) is stacked and temporarily assembled at the center in the longitudinal direction of the cylindrical tube (1), and the joining tool (10) and the probe (11) are attached. The center part of the plate member (2) in the length direction was used for friction stir welding. In the friction stir welding, the insertion position of the probe (11) is positioned in three stages as shown in Table 1 below, with the offset amount (X1) from the center line (P) to the flange (4) side, and a welding tool ( 10) was moved in the length direction of the cylindrical tube (1). In FIG. 7, (Z) is the locus of the center of the probe (11). The number of rotations of the joining tool (10) was 2000 rpm, the joining speed was 450 mm / min, and the joining distance (Z1) (the length of the probe locus (Z)) was 30 mm. The ratio of the protrusion amount (X2) and the protrusion amount (X2) to the probe (11) diameter by the offset amount (X1) is as shown in Table 1.

  Moreover, as shown in FIG. 9, as a comparative example, the center line (P) is not offset with respect to the same temporary assembly as the joint (20) without offsetting the insertion position of the probe (11) toward the plate member (2). The joint (22) was manufactured under the same tool conditions as in the previous example, with the entire tip face facing the cylindrical tube (1).

The joints manufactured in the above-described examples and comparative examples were compared in strength and durability using a static strength tester (50) shown in FIG.
[Static strength tester]
In the static strength tester (50), the load cell (51) is fixed to the upper part, and the lower base (52) is moved up and down by the cylinder (53). Then, the cylindrical pipe (1) of the test joint is fixed on the base (52) and the plate-like member (2) is connected to the load cell (51). When a cylinder (53) is lowered, a tensile load is applied.

As shown in FIG. 7, the cylindrical tube (1) has bolt holes drilled at positions of 15 mm from both tube ends, and is fixed to the base (52) through fixing bolts (54). . On the other hand, as shown in FIG. 8, the plate-like member (2) is positioned at a distance (X3): 25 mm from the center line (P) of the cylindrical tube (1) at the center in the length direction of the flange portion (4). A bolt hole (58) is formed in the bolt hole, and a fixing bolt (55) is passed through the bolt hole (57) and fixed to a jig (56) connected to the load cell (51).
〔Strength〕
The cylinder (53) was driven to lower the base (52) at a speed of 5 mm / min, and a load in the tensile direction was applied until the joint of the test joint broke. The load at break was taken as the maximum load of the joint.
〔durability〕
For the test joint, 0.32 kN in the tensile direction and 0.32 kN in the compression direction were input repeatedly at 10 Hz, and durability was evaluated by the number of repetitions until fracture.

  Table 1 shows the strength and durability of each joint.

  From the results of Table 1, it was confirmed that each joint of the example was excellent in strength and durability.

It is a perspective view which shows an example of the friction stir welding method of the metal member of this invention. It is the II-II sectional view taken on the line of FIG. It is a perspective view which shows the other example of the friction stir welding method of the metal member of this invention. It is a perspective view which shows the further another example of the friction stir welding method of the metal member of this invention. It is a perspective view which shows the further another example of the friction stir welding method of the metal member of this invention. It is a perspective view which shows the member used for the coupling manufacture of FIG. It is a top view of the coupling of FIG. It is a perspective view which shows a static strength tester and a test method. It is sectional drawing which shows the friction stir welding method in the conventional joint manufacture.

Explanation of symbols

1, A ... Cylindrical tube (rod member)
2,7,32,42, B ... Plate member
3,8,33,43… Recess for assembly
4,9,34,44… Flange
6… Round bar (bar-shaped member)
10 ... Joining tool
11,13… probe
12,14… Tip surface
20,21 ... Fitting (metal fitting)
31,41 ... Square bars (bar-shaped members)
Y1 ... one side portion Y2 of the tip surface ... other side portion X2 of the tip surface ... the amount of protrusion

Claims (12)

When performing friction stir welding in the surface contact region where the metal plate member (B) is superimposed on the outer peripheral surface of the metal rod member (A),
The rod-shaped member (A) is a rod-shaped member having a circular cross section, and an arcuate recess for assembly corresponding to the outer peripheral surface of the rod-shaped member (A) is formed on one surface of the plate-shaped member (B), Surface contact areas of both members (A) and (B) are formed by fitting a part of the rod-shaped member (A) to the assembling arcuate recess,
The probe of the friction stir welding tool is inserted at a depth where the tip of the probe penetrates the plate-like member (B) in the thickness direction and reaches the rod-like member (A). The surface is positioned so as to straddle the rod-shaped member (A) and the plate-shaped member (B),
In the inserted state of the probe, both members (A) and (B) are friction stir welded by relative movement in the longitudinal direction of the rod-shaped member (A) while rotating the welding tool. Friction stir welding method for members.   2. The metal member friction stir welding method according to claim 1, wherein the probe is positioned so that one side portion of the outer peripheral edge of the tip surface protrudes from the contact interface of the surface contact region and faces the plate-like member (B). .   2. The metal member according to claim 1, wherein the probe is positioned such that both side portions located symmetrically on the left and right sides of the outer peripheral edge of the tip surface protrude from the contact interface of the surface contact region and face the plate-like member (B). Friction stir welding method.   The protrusion amount to the plate-like member (B) side of the outer peripheral edge of the distal end surface when the probe is inserted is set to 35% or less of the distal end surface diameter of the probe. Friction stir welding method for metal members.   5. The friction stir welding method for metal members according to claim 4, wherein the protruding amount is set to 5 to 30% of the tip end face diameter of the probe. The method for friction stir welding of a metal member according to any one of claims 1 to 5 , wherein the rod member (A) is a hollow or solid rod member. The plate-like member (B) is formed with an arcuate recess for assembly at one end thereof, and the other end protrudes to the side of the rod-like member (A) when assembled with the rod-like member (A). The friction stir welding method for a metal member according to any one of claims 1 to 6 , wherein the metal member is a friction stir welding method. The method for friction stir welding of metal members according to claim 7 , wherein the insertion position of the probe is set at a position offset from the center of the rod-shaped member (A) by a predetermined distance toward the other end side . The metal member friction stir welding method according to any one of claims 1 to 8 , wherein at least one of the rod-like member (A) and the plate-like member (B) is made of aluminum or an aluminum alloy. The metal rod-like member (A) and the metal plate-like member (B) are joined by the friction stir welding method for metal members according to any one of claims 1 to 9 , and the length of the rod-like member (A). A metal joint having a stir joint formed along a direction. The metal joint according to claim 10 , wherein the metal joint is a structural metal part. The metal joint according to claim 11 , wherein the structural metal part is a vehicle metal part.

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