阅读说明：本技术 一种实现异种材料连接的差厚法搅拌摩擦焊接工艺 (Differential thickness method friction stir welding process for realizing dissimilar material connection ) 是由 薛鹏 倪丁瑞 马宗义 吴利辉 肖伯律 张振 于 2020-04-13 设计创作，主要内容包括：本发明公开了一种实现异种材料连接的差厚法搅拌摩擦焊接工艺,属于异种材料焊接技术领域。该工艺采用低熔点金属厚度大于高硬度/高熔点材料厚度的方式,并完全偏置搅拌针,避免焊接工具的磨损和断裂,同时利用较高的工具转速和/或大的轴肩压下量提高热输入促进异种材料之间的冶金结合。本发明工艺解决了现有技术中异种材料连接时焊缝难以成形、焊接质量差、焊接工具损伤、成本高等问题。本发明可以明显提高异种材料焊接接头的力学性能,尤其适用于低熔点金属(铝、铝合金、镁、镁合金等)和高硬度/高熔点材料(钢、钛合金、铜合金、非晶、陶瓷)之间的焊接。(The invention discloses a differential thickness method friction stir welding process for realizing dissimilar material connection, and belongs to the technical field of dissimilar material welding. The process adopts a mode that the thickness of the low-melting-point metal is larger than that of the high-hardness/high-melting-point material, and completely offsets the stirring pin, so that the abrasion and the breakage of a welding tool are avoided, and simultaneously, the high heat input is increased by utilizing higher tool rotating speed and/or large shaft shoulder pressing force so as to promote the metallurgical bonding between dissimilar materials. The process solves the problems of difficult formation of welding seams, poor welding quality, damage to welding tools, high cost and the like in the process of connecting dissimilar materials in the prior art. The invention can obviously improve the mechanical property of the welding joint of dissimilar materials, and is particularly suitable for welding between low-melting-point metals (aluminum, aluminum alloy, magnesium alloy and the like) and high-hardness/high-melting-point materials (steel, titanium alloy, copper alloy, amorphous and ceramic).)

1. A differential thickness method friction stir welding process for realizing dissimilar material connection is characterized in that: the process is used for butt welding between low-melting-point metal and high-hardness/high-melting-point material, and comprises the following process steps: and (3) butting and fixing the low-melting-point metal base metal and the high-hardness/high-melting-point material base metal, wherein the thickness of the low-melting-point metal base metal is larger than that of the high-hardness/high-melting-point material base metal, completely offsetting a stirring needle at one side of the low-melting-point material, and welding by using the stirring friction welding parameters with higher heat input to obtain a stirring friction welding joint of the dissimilar materials with excellent performance.

2. The friction stir welding process of claim 1, wherein the friction stir welding process comprises: the process specifically comprises the following steps:

(1) mechanically polishing the welding surfaces of the two materials, and then cleaning the welding surfaces by using alcohol or acetone;

(2) placing a high-hardness/high-melting-point material base metal on an advancing side, wherein the advancing side refers to the side with the welding direction consistent with the tool rotating direction, and clamping the welding material;

(3) selecting a welding tool with a proper size, completely offsetting the stirring pin on one side of the low-melting-point material, and selecting a higher heat input parameter to carry out friction stir welding;

(4) and after welding, milling the thicker low-melting-point material to keep the thicknesses of the two materials consistent.

3. The friction stir welding process of claim 1, wherein the friction stir welding process comprises: the thickness difference delta t between the two welded parent metals is 0.2-1 mm, and the distance l between the edge of the stirring pin and the parent metal of the high-hardness/high-melting-point material is 0-0.3 mm.

4. The friction stir welding process of the differential thickness method for realizing dissimilar material joining according to claim 3, wherein: the thickness difference delta t between two welded parent metals is 0.2-0.4 mm for a thin plate parent metal with the plate thickness of less than 3 mm and a thick plate parent metal with the plate thickness of more than 10 mm; for the medium plate base material with the plate thickness of 3-10 mm, the thickness difference delta t of the two welded base materials is 0.4-1 mm.

5. The friction stir welding process of claim 1, wherein the friction stir welding process comprises: the welding tool material is low-cost common tool steel H13 or M42, etc., the stirring pin is a cylindrical threaded pin, and the diameter of the stirring pin is 0.8-1.5 times of the thickness of the base metal plate of the high-hardness/high-melting-point material.

6. The friction stir welding process of claim 1, wherein the friction stir welding process comprises: the parameters of the friction stir welding are as follows: the rotating speed of the welding tool is 800-2000 r/min, the advancing speed is 50-200 mm/min, the reduction delta of the shaft shoulder of the welding tool is 0.1-0.8 mm, and the reduction delta of the shaft shoulder refers to the depth of the shaft shoulder of the welding tool pressed into the base material of the low-melting-point material.

7. The friction stir welding process of enhancing the mechanical properties of a joint as defined in claim 1 wherein: the low-melting-point metal is aluminum, aluminum alloy, magnesium or magnesium alloy, and the high-hardness/high-melting-point material is steel, titanium alloy, copper alloy, amorphous or ceramic material.

The technical field is as follows:

the invention relates to the technical field of material welding, in particular to a differential thickness method friction stir welding process for realizing dissimilar material connection, which is suitable for dissimilar material welding, and is particularly suitable for welding between low-melting-point metal (aluminum, aluminum alloy, magnesium and magnesium alloy) and high-hardness/high-melting-point material (steel, titanium alloy, copper alloy, amorphous and ceramic).

Background art:

the connection of dissimilar materials can give full play to the respective advantages of the two materials, and the method has very wide application in industry, and particularly has the most important connection application of low-melting-point metals (aluminum, aluminum alloy, magnesium alloy and the like) and high-hardness/high-melting-point metals (steel, copper alloy, titanium alloy, ceramic, high-temperature alloy, amorphous and the like). However, due to the great difference in physical and chemical properties between dissimilar materials, it is difficult to achieve high quality connections using conventional welding processes. Friction Stir Welding (FSW) is a solid phase welding process invented by the british institute of welding in 1991. FSW has gained increasing attention due to its many advantages in the welding of dissimilar materials. However, when welding dissimilar materials by FSW, a pin is partially offset so that a small amount of the pin is in a high hardness/high melting point material, as shown in fig. 2. The existing FSW process has great disadvantages, mainly including:

(1) because the welding tool and the shaft shoulder are required to enter high-hardness/high-melting-point materials, common welding tool materials cannot be met, and only expensive materials such as W-Re alloy, cubic boron nitride and the like can be adopted to process the welding tool, so that the cost is greatly improved, the material has poor processability, the appearance optimization of the tool is difficult to carry out, the abrasion loss can be increased due to the contact with a hard material, and a stirring needle is very easy to break, so that the finished product rate is low, and the practicability in the industry is poor;

(2) due to the stirring effect of the welding tool on the high-hardness/high-melting-point material, large-size particles of the high-hardness/high-melting-point material often exist in a welding nucleus area, the particles are very easy to become a fatigue crack source in the subsequent service process, hidden dangers are brought to practical industrial application, the flowability of the welding nucleus area is poor due to the existence of the large-size particles, defects are easily generated, and the performance of a joint is obviously reduced;

(3) for low-melting-point materials and superhard materials (ceramics, amorphous materials and the like), the existing welding tool materials cannot enter the superhard materials, and the stirring pin is broken at the welding insertion stage, so that the material system, especially the material system with a large plate thickness (more than 5mm), is usually not weldable, and the engineering application of the material system is greatly limited.

The invention content is as follows:

the invention aims to provide a differential thickness method friction stir welding process for realizing the connection of dissimilar materials, which solves the problems of overhigh welding cost, poor welding quality, low service performance of a joint, low industrial practical applicability and the like of the dissimilar materials in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a friction stir welding process by differential thickness method for realizing dissimilar material connection is used for butt welding between low-melting-point metal (aluminum, aluminum alloy, magnesium alloy and the like) and high-hardness/high-melting-point material (steel, titanium alloy, copper alloy, amorphous and ceramic), and the process flow is as follows: and (3) butting and fixing the low-melting-point metal base metal and the high-hardness/high-melting-point material base metal, wherein the thickness of the low-melting-point metal base metal is larger than that of the high-hardness/high-melting-point material base metal, and the stirring needle is completely offset at one side of the low-melting-point material and is welded according to the stirring friction welding parameters with higher heat input, so that the stirring friction welding joint of the dissimilar materials with excellent performance is obtained. The process specifically comprises the following steps:

(1) mechanically polishing the welding surfaces of the two materials, and then cleaning the welding surfaces by using alcohol or acetone;

(2) placing the high-hardness/high-melting-point material base metal on the advancing side (the side with the welding direction consistent with the tool rotating direction), and clamping the welding material;

(3) selecting a welding tool with a proper size, completely offsetting the stirring pin on one side of the low-melting-point material, and selecting a higher heat input parameter to carry out friction stir welding;

(4) and after welding, milling the thicker low-melting-point material to keep the thicknesses of the two materials consistent.

The thickness difference delta t between the two welded parent metals is 0.2-1 mm, and the distance l between the edge of the stirring pin and the parent metal of the high-hardness/high-melting-point material is 0-0.3 mm.

For a thin plate base material with the plate thickness of less than 3 mm and a thick plate base material with the plate thickness of more than 10 mm, sufficient heat input amount can be ensured only by changing welding parameters, and the thickness difference delta t of the two welded base materials is smaller and is 0.2-0.4 mm; for the medium plate base metal with the plate thickness of 3-10 mm, the heat input and the material flow are sensitive to the change of welding parameters, and in order to ensure sufficient material flow and heat input, the thickness difference delta t of the two welded base metals is larger and is 0.4-1 mm.

The welding tool material is low-cost common tool steel H13 or M42 and the like, the stirring needle is a cylindrical threaded needle, and the diameter of the stirring needle is 0.8-1.5 times of the thickness of the base metal plate of the high-hardness/high-melting-point material.

The method is characterized in that the metallurgical bonding of the dissimilar material interface is promoted by adopting higher heat input parameters in the welding process, and the friction stir welding parameters are as follows: the rotating speed of the welding tool is 800-2000 r/min, the advancing speed is 50-200 mm/min, the reduction delta of the shaft shoulder of the welding tool is 0.1-0.8 mm, and the reduction delta of the shaft shoulder refers to the depth of the shaft shoulder of the welding tool pressed into the base material of the low-melting-point material.

The low-melting-point metal is aluminum, aluminum alloy, magnesium or magnesium alloy, and the high-hardness/high-melting-point material is steel, titanium alloy, copper alloy, amorphous or ceramic material.

The invention has the beneficial effects that:

1. the invention provides a differential thickness friction stir welding process for realizing high-quality connection of dissimilar materials, which uses a steel stirring head with low price, avoids a welding tool from contacting a high-hardness/high-melting-point material by a method of completely offsetting a stirring needle at a low-melting-point material side and increasing the thickness of the low-melting-point material, and simultaneously adopts higher heat input parameters and larger shaft shoulder pressing amount to ensure heat input amount and material flow and promote metallurgical bonding of dissimilar material interfaces. Compared with the conventional process adopting expensive tungsten-rhenium alloy and cubic boron nitride welding tools, the process has the advantages that the cost is greatly reduced due to the adoption of the steel welding tool, the welding difficulty is greatly reduced due to the fact that the welding process is mainly carried out on one side of a low-melting-point material, a welding seam is easier to form under the condition that the heat input quantity and the material flow are sufficient, the mechanical property of a joint is improved, and the process is very suitable for industrial production.

2. In the differential thickness method friction stir welding process, the shaft shoulder and the stirring pin of the welding tool only contact the low-melting-point material in the welding process, so that the service life of the welding tool is greatly prolonged, and the stirring pin does not contact or is far away from the high-hardness/high-melting-point material, so that the problem that a large number of high-hardness/high-melting-point material particles enter a welding nucleus area is avoided, the defect rate is greatly reduced, the yield of products is improved, and the risk of premature formation of fatigue cracks in the subsequent service process is eliminated. Therefore, the new friction stir welding process by the differential thickness method has wide industrial application prospect in the field of dissimilar material welding.

3. The invention can obviously improve the weld forming ability of dissimilar materials, enhance the mechanical property of a welding joint, and is particularly suitable for welding between low-melting-point metals (aluminum, magnesium, alloy thereof and the like) and high-hardness/high-melting-point materials (steel, titanium, copper, amorphous and ceramic).

Description of the drawings:

FIG. 1 is a schematic view of a friction stir welding process according to the differential thickness method of the present invention; wherein: (a) an initial state; (b) a welding state; (c) after welding is finished; (d) and (5) milling.

FIG. 2 is a schematic view of a conventional friction stir welding process.

FIG. 3 shows the appearance of an aluminum-low carbon steel interface by scanning electron microscopy.

The specific implementation mode is as follows:

the invention is described in detail below with reference to the figures and examples.

The invention provides a differential thickness friction stir welding process for realizing high-quality connection between low-melting-point metal (aluminum, aluminum alloy, magnesium alloy and the like) and high-hardness/high-melting-point material (steel, titanium alloy, copper alloy, amorphous and ceramic), which is shown in figure 1 and specifically comprises the following steps:

(1) mechanically polishing the welding surfaces of the two materials, and then cleaning the welding surfaces by using alcohol or acetone;

(2) placing the high-hardness/high-melting-point material base metal on the advancing side (the side with the welding direction consistent with the tool rotating direction), and clamping the welding material;

(3) selecting a welding tool with a proper size, completely offsetting the stirring pin on one side of the low-melting-point material, and selecting a higher heat input parameter to carry out friction stir welding;

(4) and after welding, milling the thicker low-melting-point material to keep the thicknesses of the two materials consistent.

The thickness difference delta t between the two welded parent metals is 0.2-1 mm, and the distance l between the edge of the stirring pin and the parent metal of the high-hardness/high-melting-point material is 0-0.3 mm. The parameters Δ t and l are illustrated schematically in FIG. 1.

The invention is suitable for welding dissimilar metals (such as aluminum-copper, aluminum-steel, aluminum-titanium, magnesium-steel, aluminum-magnesium and the like) and metals and nonmetals (such as metal-amorphous, metal-ceramic and the like).

Example 1

A1060 pure aluminum rolled plate 5.6 mm thick was used, with a tensile strength of 120MPa and a low carbon steel Q345 5mm thick, with a tensile strength of 520 MPa. The welding tool is made of H13 steel, the diameter of the shaft shoulder is 22 mm, the stirring pin is a cylindrical threaded pin, the diameter is 6 mm, the length of the pin is 5mm, the distance between the edge of the stirring pin and the low-carbon steel is 0 mm in the welding process, the reduction of the shaft shoulder of an aluminum plate is 0.5 mm (the shaft shoulder is 0.1 mm above the low-carbon steel), and a defect-free welding joint is obtained under the welding parameters that the rotating speed of the welding tool is 1000 revolutions per minute and the advancing speed is 100 mm per minute. The structure observation shows that the interface is relatively flat, the combination is good, and no large-size steel particles appear in the welding nucleus area (figure 3). The tensile test at room temperature shows that the joint is broken in the heat affected zone on the aluminum side, and the tensile strength is 100 MPa.

Comparative example 1-1

1060 pure aluminum rolled plate (tensile strength 120MPa) and low carbon steel Q345 (tensile strength 520MPa) each having a thickness of 5mm were used. The welding tool is made of W-5Re alloy, the diameter of a shaft shoulder is 22 mm, a stirring pin is a cylindrical threaded pin, the diameter is 6 mm, the length of the pin is 4.7 mm, the pressing amount of the shaft shoulder in the welding process is 0.2 mm (the shaft shoulder is 0.2 mm below an aluminum plate), most of the stirring pin is located on the aluminum plate, the distance between the center line of the stirring pin and a welding interface is 2 mm, and the stirring pin is located in low-carbon steel by 1 mm. The weld joint was obtained at welding parameters of a welding tool speed of 1000 revolutions per minute and a travel speed of 100 mm per minute. The structure observation shows that a large amount of large-size steel particles exist in the welding nucleus area, and micropore defects are formed nearby the particles, and the room-temperature tensile test shows that the joint is broken in the welding nucleus area, the fluctuation of the tensile strength is large, and the average value is 45 MPa.

Comparative examples 1 to 2

A1060 pure aluminum rolled plate 5.6 mm thick was used, with a tensile strength of 120MPa and a low carbon steel Q345 5mm thick, with a tensile strength of 520 MPa. The welding tool is made of H13 steel, the diameter of a shaft shoulder is 22 mm, the stirring needle is a cylindrical threaded needle, the diameter is 6 mm, the length of the needle is 5mm, the distance between the edge of the stirring needle and the low-carbon steel is 0 mm in the welding process, the shaft shoulder reduction amount of an aluminum plate is 0.5 mm (the shaft shoulder is 0.1 mm above the low-carbon steel), welding is carried out under the welding parameters that the rotating speed of the welding tool is 400 r/min and the advancing speed is 100 mm/min, however, due to the fact that the rotating speed is too low, heat input is insufficient, good metallurgical bonding is not formed between aluminum and steel, and a room temperature tensile test shows that a joint is broken at an interface, and the tensile strength is only about 40 MPa.

Comparative examples 1 to 3

A1060 pure aluminum rolled plate 5.2 mm thick was used, with a tensile strength of 120MPa and a low carbon steel Q345 5mm thick, with a tensile strength of 520 MPa. The welding tool is made of H13 steel, the diameter of a shaft shoulder is 22 mm, the stirring needle is a cylindrical threaded needle, the diameter is 6 mm, the length of the needle is 5mm, the distance between the edge of the stirring needle and low-carbon steel is 0 mm in the welding process, the shaft shoulder pressing amount of an aluminum plate is 0.1 mm (the shaft shoulder is 0.1 mm above the low-carbon steel), welding is carried out under the welding parameters that the rotating speed of the welding tool is 1000 revolutions per minute and the advancing speed is 100 mm per minute, however, the shaft shoulder pressing amount is too small due to small difference in thickness, the material flow and the heat input amount are not enough, a welding seam cracks after welding is finished, and welding is not finished successfully.

Comparative examples 1 to 4

A1060 pure aluminum rolled plate 6.2 mm thick was used, with a tensile strength of 120MPa and a low carbon steel Q345 5mm thick, with a tensile strength of 520 MPa. The welding tool is made of H13 steel, the diameter of a shaft shoulder is 22 mm, the stirring needle is a cylindrical threaded needle, the diameter is 6 mm, the length of the needle is 5mm, the distance between the edge of the stirring needle and low-carbon steel is 0 mm in the welding process, the shaft shoulder pressing amount of a reference aluminum plate is 1.1 mm (the shaft shoulder is 0.1 mm above the low-carbon steel), welding is carried out under the welding parameters that the rotating speed of the welding tool is 1000 revolutions per minute and the advancing speed is 100 mm per minute, however, the shaft shoulder pressing amount is too large due to large difference, the welding process is extremely unstable, the welding equipment vibrates greatly, long-distance welding is difficult to complete, and the defect of intermittent holes on the surface is caused by excessive material accumulation below the shaft shoulder. Microstructure shows that the thickness of an interface intermetallic compound reaches 5 micrometers due to overlarge heat input caused by overlarge shaft shoulder reduction and overlarge material flow, a mixed layer structure of the compound and a steel strip is formed, the width reaches 50 micrometers, and a room-temperature tensile test shows that a joint is broken at the interface, and the tensile strength is only about 50 MPa.

Example 2

A20.2 mm thick 1060 pure aluminum plate was used, with a tensile strength of 110MPa and a 20 mm thick Q345 plate of mild steel, with a tensile strength of 520 MPa. The welding tool is made of H13 steel, the diameter of the shaft shoulder is 30 mm, the stirring pin is a cylindrical threaded pin, the diameter is 14 mm, the length of the pin is 20 mm, the distance between the edge of the stirring pin and the low-carbon steel is 0.3 mm in the welding process, the reduction of the shaft shoulder of an aluminum plate is 0.2 mm (the shaft shoulder is 0.1 mm above the low-carbon steel), and a defect-free welding joint is obtained under the welding parameters that the rotating speed of the welding tool is 800 r/min and the advancing speed is 50 mm/min. The structure observation shows that the interface is relatively flat and straight, and no large-size steel particles appear in a welding nucleus area. The tensile test at room temperature shows that the joint is broken in the heat affected zone on the aluminum side, and the tensile strength is 95 MPa.

Comparative example 2

1060 pure aluminum rolled plate (tensile strength 120MPa) and low carbon steel Q345 (tensile strength 520MPa) each having a thickness of 20 mm were used. The welding tool M42 steel was made (W-Re alloy and cubic boron nitride are difficult to make and extremely expensive, so this comparative example used M42 steel to make the tool), the diameter of the shaft shoulder was 30 mm, the stirring pin was a cylindrical screw pin, the diameter was 14 mm, the pin length was 19.7 mm, the reduction of the shaft shoulder during welding was 0.2 mm (the shaft shoulder was 0.2 mm below the aluminum plate), the stirring pin was mostly located on the aluminum plate, the center line of the stirring pin was 6 mm from the welding interface, i.e. the stirring pin was 1 mm in low carbon steel. Under the welding parameters that the rotating speed of the welding tool is 800 revolutions per minute and the advancing speed is 50 millimeters per minute, the welding tool fails to work at a distance of about 10 millimeters during welding, the stirring pin is broken, the shaft shoulder is seriously deformed, and the welding process cannot be completed.

Example 3

A7075-T651 aluminum alloy 2 mm thick, 575MPa tensile strength and 1.8 mm thick zirconium-based amorphous (Zr) alloy was used₅₅Cu₃₀Al₁₀Ni₅) And (3) a plate. The welding tool is made of M42 steel material, the diameter of the shaft shoulder is 18 mm, the stirring pin is a cylindrical threaded pin, the diameter is 4 mm, the length of the pin is 1.8 mm, the distance between the edge of the stirring pin and the low-carbon steel is 0.3 mm in the welding process, the shaft shoulder pressing amount of an aluminum plate is 0.1 mm (the shaft shoulder is 0.1 mm above the amorphous plate), and a defect-free welding joint is obtained under the welding parameters that the rotating speed of the welding tool is 2000 r/min and the advancing speed is 200 mm/min. The observation of the structure shows that the interface is relatively flat and straight, and no amorphous particles appear in a weld nucleus area. The tensile test at room temperature shows that the joint is broken in the heat affected zone on the aluminum side, and the tensile strength is 450 MPa.

Comparative example 3

7075-T aluminum alloy plate (tensile strength of 575MPa) and zirconium-based amorphous (Zr) plates (both 1.8 mm in thickness) were used₅₅Cu₃₀Al₁₀Ni₅) And (3) a plate. The welding tool is made of W-25Re alloy, the diameter of a shaft shoulder is 18 mm, a stirring pin is a cylindrical threaded pin, the diameter is 4 mm, the length of the pin is 1.6 mm, the pressing amount of the shaft shoulder in the welding process is 0.2 mm (the shaft shoulder is 0.1 mm below an aluminum plate), most of the stirring pin is located on the aluminum plate, the distance between the center line of the stirring pin and a welding interface is 1.5 mm, and the stirring pin is located in an amorphous state by 0.5 mm. The weld joint was obtained at welding parameters of a welding tool speed of 2000 revolutions per minute and a travel speed of 200 mm per minute. The observation of the structure shows that the welding nucleus area has large-size amorphous particles, and micropore defects are formed near the particles, the tensile test at room temperature shows,the joint is broken in a weld nucleus area, the fluctuation of the tensile strength is large, and the average value is 150 MPa.

Example 4

8.6 mm thick 6061-T6 aluminum alloy, tensile strength 315MPa and 8 mm thick TC4 titanium alloy, tensile strength 950MPa were used. The welding tool is made of H13 steel, the diameter of a shaft shoulder is 22 mm, a stirring pin is a cylindrical threaded pin, the diameter is 8 mm, the length of the pin is 8 mm, the edge distance TC4 of the stirring pin in the welding process is 0.2 mm, the reduction of the shaft shoulder of an aluminum plate is 0.5 mm (the shaft shoulder is 0.1 mm above the titanium alloy plate), and a defect-free welding joint is obtained under the welding parameters that the rotating speed of the welding tool is 1000 revolutions per minute and the advancing speed is 100 mm per minute. The observation of the structure shows that the interface is relatively flat and straight, and no amorphous particles appear in a weld nucleus area. The tensile test at room temperature shows that the joint is broken in the heat affected zone on the aluminum side, and the tensile strength is 280 MPa.

Comparative example 4

6061 aluminum alloy plate (tensile strength 315MPa) and TC4 titanium alloy (tensile strength 950MPa) both having a thickness of 8 mm were used. The welding tool is W-25Re alloy, the diameter of a shaft shoulder is 22 mm, the stirring pin is a cylindrical threaded pin, the diameter is 8 mm, the length of the pin is 7.7 mm, the reduction of the shaft shoulder in the welding process is 0.2 mm (the shaft shoulder is 0.2 mm below an aluminum plate), most of the stirring pin is positioned on the aluminum plate, the distance between the center line of the stirring pin and a welding interface is 3 mm, namely 1 mm of the stirring pin is positioned in the titanium alloy. The weld joint was obtained at welding parameters of a welding tool speed of 1000 revolutions per minute and a travel speed of 100 mm per minute. The structural observation shows that a large number of large-size titanium alloy particles exist in a welding nucleus area, and micropore defects are formed nearby the particles, and a room-temperature tensile test shows that a joint is broken in the welding nucleus area, the fluctuation of the tensile strength is large, and the average value is 110 MPa.

Example 5

6 mm thick 1060 pure aluminum, tensile strength 120MPa and 5mm thick Al were used₂O₃The surface of the ceramic is metallized in advance, and a nickel metal film is electroplated on the surface. The welding tool is made of H13 steel material, the diameter of the shaft shoulder is 20 mm, the stirring needle is a cylindrical threaded needle with the diameter of 6 mm and the length of 5.1 mm, and the stirring needle is weldedDistance Al between the edges of the stirring pins in the process₂O₃A weld joint free of defects was obtained at a weld tool speed of 1500 rpm and a travel speed of 50 mm/min with 0.1 mm of ceramic, referenced to a shoulder reduction of 0.8 mm of aluminum plate (shoulder 0.2 mm above ceramic material). The observation of the structure shows that the interface is flat and straight, and no particles appear in the weld nucleus area. The tensile test at room temperature shows that the joint is broken in the heat affected zone on the aluminum side, and the tensile strength is 95 MPa.