Friction stir welding method for steel-aluminum composite material rim

Abstract

The invention discloses a friction stir welding method for a steel-aluminum composite material rim, which comprises the following steps of: processing a to-be-welded surface of an aluminum alloy rim into an inclined surface shape, and processing a steel spoke into a matched inclined surface shape; a transition material is taken, and the two sides of the transition material are machined into corresponding slope shapes; a transition material is placed between the butt-joint inclined faces of the aluminum alloy rim and the steel spoke to serve as a to-be-welded area, and the to-be-welded area comprises a first butt-joint welding seam between the aluminum alloy rim and the transition material and a second butt-joint welding seam between the steel spoke and the transition material; the to-be-welded area is heated; and the first lap joint welding seam and the second lap joint welding seam are welded through a pumpback type stirring friction tool. According to the method, high-strength connection is achieved through slope design, preheating optimization and a double-weld-joint structure, meanwhile, the integrity and corrosion resistance of weld joints are improved through the pumpback technology and transition materials, and the requirements for light weight and safety of automobiles are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of friction stir welding manufacturing of automobile wheel rim, and particularly relates to a friction stir welding method of steel-aluminum composite wheel rim. BACKGROUND

[0002] Automobile lightening has become a consensus in the global automobile industry development, and the weight reduction of wheel rim can significantly reduce energy consumption, improve the acceleration and braking performance of vehicle, and thus improve the driving comfort and safety.

[0003] The wheel rim can be divided into steel wheel rim and aluminum alloy wheel rim according to the material, the steel wheel rim has high strength, high durability and is not easy to crack, and has high cost performance, but the steel wheel rim has large weight, poor heat dissipation and is easy to rust; the aluminum alloy wheel rim has light weight, high strength and good heat dissipation performance, but the strength of the aluminum alloy wheel rim is relatively low, and the manufacturing cost is relatively high.

[0004] At present, the wheel rim for automobile is either steel material or aluminum alloy material, with the increasingly strict requirements of energy saving and emission reduction, how to make full use of the respective advantages of steel and aluminum alloy, that is, to have high rigidity, light weight and good heat dissipation, the steel-aluminum composite wheel rim is in great demand, but the connection of steel and aluminum alloy is involved.

[0005] It is well known that the physical properties and metallurgical properties of steel and aluminum alloy are quite different, for example, the melting point of steel is about 1500 DEG C, and the melting point of aluminum alloy is 660 DEG C, the traditional fusion welding is difficult to effectively weld the two together, and the sealing performance of cold connection such as riveting and screwing is poor, which cannot meet the use performance of the wheel rim. As an important part of automobile, the connection of steel and aluminum alloy becomes a problem to be solved. SUMMARY

[0006] The purpose of the present application is to provide a manufacturing method of steel-aluminum composite wheel rim, so as to solve the problem that steel and aluminum alloy are difficult to be welded together due to different melting points.

[0007] In order to achieve the above purpose, the technical scheme provided by the present application is to provide a friction stir welding method of steel-aluminum composite wheel rim, comprising:

[0008] S1, processing the welding surface of the aluminum alloy wheel rim into a bevel shape, and processing the steel spoke into a bevel shape matched with the bevel shape of the aluminum alloy wheel rim;

[0009] S2, taking a transition material, and processing the two sides of the transition material into bevel shapes corresponding to the bevel shape of the aluminum alloy wheel rim and the welding surface shape of the steel spoke respectively;

[0010] S3, the transition material is placed between the aluminum alloy rim and the steel spoke butt bevel, as the welding area, the welding area contains the first butt joint between the aluminum alloy rim and the transition material, and the second butt joint between the steel spoke and the transition material;

[0011] S4, heating the welding area;

[0012] S5, using a retractable friction stir tool to weld the first butt joint and the second butt joint respectively.

[0013] To optimize the above technical solutions, the specific measures taken also include:

[0014] The acute angle of the rim welding surface in step S1 is 10°-28°, and the acute angle of the spoke welding surface is 10°-28°, and the angles are matched.

[0015] Further, the transition material in step S2 is aluminum alloy or zinc plate.

[0016] In step S4, the continuous heating is electromagnetic induction heating to 200-300℃, and the heating rate is 20-40℃ / s.

[0017] In step S5, the length of the stir pin used in the retractable friction stir welding is 0.5-1mm greater than the thickness of the steel spoke.

[0018] Further, in step S5, the welding parameters of the first butt joint are: spindle rotation speed 200-3000r / min, feed speed 100-1200mm / min; after completing the whole circle welding, the retracting speed is 10-20mm / min.

[0019] Further, in step S5, when welding the second joint, the spoke is on the upper part and the rim is on the lower part, the rotation speed of the spindle is 100-2000r / min, the feed speed is 50-900mm / min, and after completing the whole circle welding, the retracting speed is 5-15mm / min.

[0020] Further, when welding the first butt joint and the second butt joint, after completing 360° welding, the stir pin is retracted upward to the lower end surface of the shaft shoulder, and the spoon hole at the end of the friction stir welding is eliminated.

[0021] During the welding process of the first butt joint and the second butt joint, the stir pin is offset to one side of the aluminum alloy rim;

[0022] Further, when the connection strength of the first joint welded in step S5 meets the design requirements, the welding of the second butt joint can be omitted.

[0023] Compared with the prior art, the present application has the beneficial effects that:

[0024] The present application realizes high-strength connection of the steel-aluminum composite rim through the friction stir welding technology, and specifically, the method effectively solves the problems of large melting point difference and poor metallurgical compatibility of steel and aluminum materials by using the slope cooperation design and preheating process; the interface wettability and electrochemical corrosion performance are optimized through the transition material; the spoon hole defect is eliminated by using the back-pumping type friction stir welding tool to ensure the integrity of the weld; the double-weld design significantly improves the joint strength, and finally realizes the manufacturing of the composite rim with the advantages of high rigidity of steel and lightweight of aluminum alloy, and meets the dual requirements of automobile lightweight and safety. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 : A schematic diagram of a friction stir welding device for a steel-aluminum composite rim.

[0026] Figure 2 : A schematic diagram of a back-pumping type friction stir welding tool structure.

[0027] Figure 3 : A macroscopic morphology diagram of the butt joint of the present application.

[0028] Figure 4 : A macroscopic morphology diagram of the upper surface of the butt joint of the present application.

[0029] Figure 5 : A stress-strain curve diagram of the butt joint during the tensile process of the present application.

[0030] Figure 6 : A hardness change curve of the thickness center of the butt joint of the present application.

[0031] In the figure: 1 - rim, 2 - spoke, 3 - stirring needle, 4 - shoulder, 5 - heating device, 6 - transition material. DETAILED DESCRIPTION

[0032] The above content of the present application will be further described in detail in the form of specific embodiments, but it should not be understood that the scope of the above subject matter of the present application is limited to the following examples only, and any technology realized based on the above content of the present application belongs to the scope of the present application. In addition, the terms such as "first, second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0033] As shown in Figure 1 and Figure 2 , the technical scheme provided by the present application is to provide a friction stir welding method for a steel-aluminum composite rim, comprising:

[0034] S1, the surface to be welded of the aluminum alloy wheel rim 1 is processed into a bevel shape, and the steel spoke 2 is processed into a bevel shape matching the bevel shape of the aluminum alloy wheel rim 1;

[0035] S2, a piece of transition material 6 is taken, and the two sides of the transition material 6 are respectively processed into bevel shapes corresponding to the bevel shape of the aluminum alloy wheel rim 1 and the surface to be welded of the steel spoke 2;

[0036] S3, the transition material 6 is placed between the abutting bevels of the aluminum alloy wheel rim 1 and the steel spoke 2 as a welding area to be welded, which contains a first abutting weld between the aluminum alloy wheel rim 1 and the transition material 6 and a second abutting weld between the steel spoke 2 and the transition material 6;

[0037] S4, the welding area to be welded is heated;

[0038] S5, the first abutting weld and the second abutting weld are welded respectively by using a back-pulling friction stir tool. In some embodiments, the wheel rim 1 is made of aluminum alloy, generally die-cast aluminum alloy such as A356, ADC12, AlSi10Mg, etc., and can also be 5-series aluminum alloy and 6-series aluminum alloy.

[0039] As a preferred, the spoke 2 is low-carbon steel, generally low-carbon steel with good stamping performance such as SPEC, and in order to improve the electrochemical corrosion resistance, the surface of the steel is generally plated with zinc alloy, and the thickness of the plating layer is generally about 0.07mm-0.1mm.

[0040] As a preferred, the thickness of the spoke 2 is generally 2-5mm.

[0041] As a preferred, the acute angle of the slope set on the abutting surface of the wheel rim 1 in step S1 is generally 10-22°, and similarly, the acute angle of the slope of the abutting surface of the spoke 2 is also 10-28°, and the angles of the two are matched.

[0042] The transition material 6 in step S2 is 5-series aluminum alloy or zinc plate, which can increase the wettability of the steel-aluminum abutting surface, optimize the mechanical properties of the joint, and also improve the electrochemical corrosion performance of the steel-aluminum abutting surface, and the thickness is generally 0.2-0.4mm.

[0043] In some embodiments, the continuous heating in step S4 adopts electromagnetic induction heating, and the heating temperature is generally about 200-300℃, the temperature rising rate is 20-40℃ / s, and the holding time is 2-5min. The temperature of the surface to be welded is ensured to be relatively uniform.

[0044] Preferably, the materials of the pin 3 and the shoulder 4 of the retractable friction stir welding in step S5 are W-Re alloy or PCBN; the length of the pin 3 used in the retractable friction stir welding is 0.5-1 mm greater than the thickness of the steel spoke 2.

[0045] The welding parameters of the first lap joint in step S5 are as follows: the rotation speed of the spindle is 200-3000 r / min, and the feeding speed is 100-1200 mm / min; after the whole circle welding is completed, the retracting speed is 10-20 mm / min.

[0046] In the second lap joint, the spoke 2 is on the upper part, and the rim 1 is on the lower part, the rotation speed of the spindle is generally 100-2000 r / min, the feeding speed is generally 50-900 mm / min, and after the whole circle welding is completed, the retracting speed is 5-15 mm / min.

[0047] When the connection strength of the first joint in step S5 meets the design requirements, the second lap joint can be omitted.

[0048] In some embodiments, example 1 is the welding of the composite rim of the ADC12 die-cast aluminum alloy rim 1 and the 6 mm SPEC spoke 2, the transition material 6 is 5083 aluminum alloy, the angle of the pin 3 is 26°, and the chemical compositions of the aluminum alloy and the steel are shown in Tables 1 and 2.

[0049] Table 1 Chemical composition table of ADC12 aluminum alloy (mass. %)

[0050] Element Si Fe Cu Mn Mg Ni Zn Sn Al Content 10.2 0.85 2.1 0.45 0.27 0.48 1.0 0.29 Balance

[0051] Table 2 Chemical composition table of SPEC steel (mass. %)

[0052] Element C Mn S P Fe Content 0.075 0.45 0.028 0.027 Balance

[0053] The specific steps of example 1 are as follows:

[0054] Step S1: The outer shape and the butt joint surface of the ADC12 die-cast aluminum alloy rim 1 to be welded are processed into a 26° slope; the butt joint surface of the SPEC steel spoke 2 is processed into a slope angle corresponding to the ADC12 rim 1, which is 64° at this time.

[0055] Step S2: The two sides of the 5083 aluminum alloy transition material 6 are processed into the slope angles corresponding to the rim 1 and the spoke 2, so that one side cooperates with the rim 1 and the other side cooperates with the spoke 2.

[0056] Step S3: The ADC12 rim 1, the transition material 6, and the SPEC spoke 2 are installed on the corresponding tooling to ensure that the bevels cooperate with each other.

[0057] Step S4, heating the position of the spoke 2 to be welded of the SPEC by using the heating device 5, the temperature of heating is generally about 220℃, keeping 4 minutes, ensuring the temperature uniformity of the corresponding position.

[0058] Step S5, welding the butt joint surface of the aluminum alloy rim 1, the transition material 6 and the steel spoke 2 by using the retraction pin 3 and the retraction shoulder 4, the welding depth is 6.5mm, during the welding process, the retraction pin 3 is deviated to the side of the die-cast aluminum alloy rim 1 about 7.5mm.

[0059] Under the drive of the external tooling, the aluminum alloy rim 1, the transition material 6 and the steel spoke 2 rotate, rotating 360°; when the external tooling drives the aluminum alloy rim 1, the transition material 6 and the steel spoke 2 to rotate to 361°, the retraction pin 3 is driven by the external motor to move upward relative to the retraction shoulder 4, the moving speed is 20mm / min, until the lower end surface of the retraction pin 3 is flush with the lower end surface of the retraction shoulder 4, eliminating the spoon hole of the welding.

[0060] The retraction pin 3 is driven by the motor to move downward relative to the shoulder 4, extending 6.5mm out of the shoulder 4.

[0061] Then, the second welding seam of the preheated spoke 2 and the rim 1 after the cooperation is carried out, that is, the lap welding seam is carried out by the friction stir welding lap welding; under the drive of the external tooling, the aluminum alloy rim 1 and the steel spoke 2 rotate, rotating 360°.

[0062] When the external tooling drives the aluminum alloy rim 1 and the steel spoke 2 to rotate to 361°, the retraction pin 3 is driven by the external motor to move upward relative to the retraction shoulder 4, the moving speed is 20mm / min, until the lower end surface of the retraction pin 3 is flush with the lower end surface of the retraction shoulder 4, eliminating the spoon hole of the welding, completing the welding of the second lap welding seam.

[0063] Example 2 is the welding of the composite rim of the ADC12 die-cast aluminum alloy rim 1 and the 3mm SPEC spoke 2, the transition material 6 is the zinc plate, and the oblique angle of the pin 3 is 18°.

[0064] The specific steps of Example 2 are as follows:

[0065] Step S1, processing the outer shape and the butt joint surface to be welded of the ADC12 die-cast aluminum alloy rim 1 into an 18° slope; processing the butt joint surface of the SPEC steel spoke 2 into the slope angle corresponding to the ADC12 rim 1, which is 72° at this time.

[0066] Step S2, processing the two sides of the transition material 6 made of zinc alloy into the slope angle corresponding to the rim 1 and the spoke 2, so that one side cooperates with the rim 1 and the other side cooperates with the spoke 2.

[0067] Step S3, the ADC 12 rim 1, transition material 6, SPEC spoke 2 are installed on the corresponding tooling, ensuring that the bevels mate with each other.

[0068] Step S4, the SPEC spoke 2 position to be welded is heated using the heating device 5, the heating temperature is generally about 260°C, and the temperature is maintained for 3 min to ensure uniform temperature at the corresponding position.

[0069] Step S5, the aluminum alloy rim 1, transition material 6 and steel spoke 2 are welded at the butt joint surface using the retractable stirring needle 3 and retractable shaft shoulder 4, the welding depth is 3.5 mm, and during the welding process, the retractable stirring needle 3 is deviated to one side of the die-cast aluminum alloy rim 1 by about 4.5 mm.

[0070] The aluminum alloy rim 1, transition material 6 and steel spoke 2 are rotated under the drive of the external tooling, and the rotation is 360°.

[0071] When the aluminum alloy rim 1, transition material 6 and steel spoke 2 are rotated to 361° under the drive of the external tooling, the retractable stirring needle 3 is moved upward relative to the retractable shaft shoulder 4 under the drive of the external motor, the movement speed is 20 mm / min, and the lower end surface of the retractable stirring needle 3 is flush with the lower end surface of the shaft shoulder 4 until the spoon hole of the welding is eliminated.

[0072] The retractable stirring needle 3 is moved downward relative to the shaft shoulder 4 under the drive of the motor, and the retractable stirring needle 3 is extended from the shaft shoulder 4 by 3.5 mm.

[0073] The second welding seam, i.e., the lap welding seam, of the spoke 2 and the rim 1 after the preheating is completed is subjected to friction stir lap welding.

[0074] The aluminum alloy rim 1 and the steel spoke 2 are rotated under the drive of the external tooling, and the rotation is 360°.

[0075] When the aluminum alloy rim 1 and the steel spoke 2 are rotated to 361° under the drive of the external tooling, the retractable stirring needle 3 is moved upward relative to the retractable shaft shoulder 4 under the drive of the external motor, the movement speed is 20 mm / min, and the lower end surface of the retractable stirring needle 3 is flush with the lower end surface of the shaft shoulder 4 until the spoon hole of the welding is eliminated, and the welding of the second lap welding seam is completed.

[0076] Table 3 Chemical composition table of 6061 aluminum alloy (mass. %)

[0077] Element Si Fe Cu Mn Mg Cr Zn Ti Al Content 0.65 0.65 0.25 0.15 1.12 0.27 0.25 0.15 Balance

[0078] Table 4 Chemical composition table of IF steel (mass. %)

[0079] Element C Mn S P Ti Fe Content 0.005 0.25 0.018 0.017 0.15 Balance

[0080] Example 3 is a welding of a composite wheel rim of a 6061 aluminum alloy wheel rim 1 and a 4mm IF steel spoke 2, without transition material 6, and the skew angle of the stir pin 3 is 18°.

[0081] The specific steps of Example 3 are as follows:

[0082] Step S1, the profile of the 6061 aluminum alloy wheel rim 1 and the butt joint surface to be welded are processed into a 18° slope; the butt joint surface of the IF steel spoke 2 is processed into a slope angle corresponding to the 6061 wheel rim 1, which is 72° at this time; the 6061 aluminum alloy wheel rim 1 and the IF steel spoke 2 are installed on the corresponding tooling to ensure that the bevels cooperate with each other.

[0083] Step S2, the position to be welded of the IF steel spoke 2 is heated by using the heating device 5, and the heating temperature is generally about 200-300°C, which is maintained for 2-5 min to ensure that the temperature at the corresponding position is uniform.

[0084] Step S3, the butt joint surface of the aluminum alloy wheel rim 1 and the steel spoke 2 is welded by using the retractable stir pin 3 and the retractable shoulder 4, and the welding depth is 4.5mm. During the welding process, the retractable stir pin 3 is deviated to the side of the aluminum alloy wheel rim 1 by about 5.5mm.

[0085] Under the driving of the external tooling, the aluminum alloy wheel rim 1 and the steel spoke 2 rotate by 360°.

[0086] When the external tooling drives the aluminum alloy wheel rim 1 and the steel spoke 2 to rotate to 361°, the retractable stir pin 3 moves upward relative to the retractable shoulder 4 under the driving of the external motor at a speed of 20mm / min until the lower end face of the retractable stir pin 3 is flush with the lower end face of the retractable shoulder 4 to eliminate the spoon hole of the welding.

[0087] Step S4, the retractable stir pin 3 moves downward relative to the shoulder 4 under the driving of the motor by 4.5mm;

[0088] The second weld, i.e. the lap weld, of the spoke 2 and the rim 1 after the preheating is performed by friction stir welding lap welding.

[0089] Under the driving of the external tooling, the aluminum alloy wheel rim 1 and the steel spoke 2 rotate by 360°.

[0090] When the external tooling drives the aluminum alloy wheel rim 1 and the steel spoke 2 to rotate to 361°, the retractable stir pin 3 moves upward relative to the retractable shoulder 4 under the driving of the external motor at a speed of 20mm / min until the lower end face of the retractable stir pin 3 is flush with the lower end face of the retractable shoulder 4 to eliminate the spoon hole of the welding, and the welding of the second lap weld is completed.

[0091] In some embodiments, as Figure 3and Figure 4 As shown in FIG. 1, the overall macrostructure of the butt joint after friction stir welding of the steel-aluminum composite wheel rim is shown; the welded interfaces of the aluminum alloy rim 1, the steel spoke 2 and the transition material 6 should be clearly shown.

[0092] In some embodiments, as shown in FIG. 2, the figure shows the mechanical performance characteristics of the steel-aluminum composite wheel rim friction stir welded joint, and the stress-strain relationship is recorded by tensile test. The curve can reflect the key indicators such as yield strength, tensile strength and elongation of the joint, and prove whether the joint after welding can meet the requirements of the rim to withstand complex loads during vehicle driving. Combined with the data of Example 1 in the present application (such as the welding of ADC12 aluminum alloy and SPEC steel), the curve should reflect the strength optimization effect achieved by the bevel matching, preheating process and double weld seam design. Figure 5 As shown in FIG. 3, the figure presents the hardness distribution of the center line of the cross section of the welded joint, reflecting the microstructure evolution of the material under the action of welding thermal-mechanical coupling. Generally, the welding of steel-aluminum dissimilar materials will cause a sudden change in hardness due to thermal physical differences, but the transition material 6 (such as 5083 aluminum alloy or zinc plate) and preheating technology (200-300℃) used in the present application can moderate this gradient, making the curve present a more gentle transition, thereby verifying the improvement effect of the welding process on the interface metallurgical bonding.

[0093] Figure 6 As shown in FIG. 4, the figure presents the hardness distribution of the center line of the cross section of the welded joint, reflecting the microstructure evolution of the material under the action of welding thermal-mechanical coupling. Generally, the welding of steel-aluminum dissimilar materials will cause a sudden change in hardness due to thermal physical differences, but the transition material 6 (such as 5083 aluminum alloy or zinc plate) and preheating technology (200-300℃) used in the present application can moderate this gradient, making the curve present a more gentle transition, thereby verifying the improvement effect of the welding process on the interface metallurgical bonding.

[0094] Figure 5 and Figure 6 Together, they jointly demonstrate the technical advantages of the present application in achieving reliable connection of steel and aluminum through friction stir welding, specifically: the stress-strain curve proves that the joint strength meets the rim use standard, and the hardness distribution curve shows that the process effectively controls the generation of brittle phases at the interface of dissimilar materials.

[0095] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any skilled person in the art, without departing from the scope of the technical solution of the present application, can make any simple modification, equivalent replacement and improvement to the above embodiments according to the technical essence of the present application, which still falls within the protection scope of the present application.​

Claims

1. A method for friction stir welding of steel-aluminum composite wheel rims, characterized in that, include: S1, the surface to be welded on the aluminum alloy rim is machined into a bevel shape, and the steel spokes are machined into a bevel shape that matches the bevel shape of the aluminum alloy rim. S2, take a piece of transition material, and process the two sides of the transition material into bevel shapes that correspond to the bevel shape of the aluminum alloy rim and the shape of the steel spoke to be welded; S3, place the transition material between the butt joint bevels of the aluminum alloy rim and the steel spokes as the area to be welded. The area to be welded contains the first butt lap weld between the aluminum alloy rim and the transition material, and the second butt lap weld between the steel spokes and the transition material. S4, heat the area to be welded; S5, using a retractable friction stir tool, weld the first lap weld and the second lap weld respectively.

2. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: In step S1, the acute angle of the inclined surface to be welded on the rim is 10° to 28°, and the acute angle of the inclined surface to be welded on the spoke is 10° to 28°, and the two angles are matched.

3. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: The transition material in step S2 is aluminum alloy or zinc plate.

4. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: In step S4, the continuous heating is carried out using electromagnetic induction heating to 200-300°C, with a heating rate of 20-40°C / s.

5. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: In step S5, the length of the stirring needle of the retractable stirring friction tool is 0.5 to 1 mm greater than the thickness of the steel wheel spokes.

6. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: The welding parameters for the first lap weld in step S5 are: spindle rotation speed of 200-3000 r / min and feed speed of 100-1200 mm / min; after completing the full circle welding, the weld is pulled back at a speed of 10-20 mm / min.

7. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: In step S5, when the second weld is the lap weld, the spokes are on the upper part and the rim is on the lower part. The rotation speed of the main shaft is 100-2000 r / min and the feed speed is 50-900 mm / min. After completing the full circle welding, retract at a speed of 5-15 mm / min.

8. The friction stir welding method for steel-aluminum composite wheel rims according to claim 6 or 7, characterized in that: The retraction refers to the process of pulling the stirring pin back upwards to be flush with the lower end face of the shoulder after completing the 360° welding, thus eliminating the keyhole at the end of the friction stir welding.

9. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: During the welding process of the first and second lap welds, the stirring pin shifts to one side of the aluminum alloy rim.

10. The friction stir welding method for steel-aluminum composite wheel rims according to claim 1, characterized in that: If the connection strength of the first weld in step S5 meets the design requirements, the second weld for the lap joint is omitted.

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