CN110814512A - A kind of friction stir welding method of thin gauge titanium steel layered composite plate - Google Patents

Abstract

The invention discloses a friction stir welding method for a thin-gauge titanium-steel layered composite plate. Firstly, the titanium-steel clad plate is prepared by the explosive rolling composite process, and the thickness of the steel is greater than that of the titanium plate. Before welding, select the heat input according to the size of the composite plate, and calculate the inter-shaft pressure and reduction, the rotation speed of the stirring head and the welding speed. During welding, the thin layer material (titanium plate) of the composite plate is on top, and the same material of the composite plate is butted against each other. The heat input is controlled at 9~20kJ/mm, the rotation speed of the stirring head is 300~500r/min, the welding speed is 40~60mm/min, and the downward pressure between the shafts of the stirring head is 0.1~0.2mm, which is less than the thickness of the titanium layer. Compared with traditional material fusion welding, the method of the invention avoids a series of welding defects such as shrinkage holes, inclusions, cracks, etc., reduces the formation of Fe-Ti intermetallic compounds, and obtains beautiful appearance, less burr defects, high dimensional accuracy, Welded joints of good quality realize the effective connection of thin-gauge titanium-steel laminated composite panels.

Description

A kind of friction stir welding method of thin gauge titanium steel layered composite plate

technical field

The invention belongs to the field of welding, and relates to a friction stir welding method for a thin-gauge titanium-steel layered composite plate.

Background technique

The steel in the titanium-steel clad plate is used as a structural member, and the titanium alloy is used as an anti-corrosion coating, which makes the titanium-steel clad plate have excellent corrosion resistance and toughness, and is widely used in the petrochemical industry. The equipment prepared by using titanium-steel clad plate, the titanium alloy is in contact with the solution in the container, and the steel is used as the outer wall, which not only ensures the corrosion resistance of the container, but also ensures the strength and rigidity of the equipment.

With the continuous development of the lightweight industry, the application of thin-gauge titanium-steel laminated composite panels has attracted more and more attention. However, due to the many problems in the connection of thin-gauge titanium steel layered composite plates, defects such as shrinkage cavities and cracks are formed in the ordinary fusion welding process, especially the formation of more Fe-Ti intermetallic compounds, and the quality of welded joints is poor. deteriorating performance.

Friction stir welding is a new type of solid-phase joining technology. During the welding process, the stirring head rotates and moves along the weld, and the material at the weld heats up, softens, flows and mixes through intense frictional heat generation and strong plastic deformation. Recrystallization to form a uniform and fine equiaxed grain structure to achieve material connection. The working temperature of friction stir welding is lower than the melting point of the material to be welded, which can effectively avoid various defects in the fusion welding process and reduce the formation of brittle intermetallic compounds. Therefore, it has broad application prospects in the connection of dissimilar materials.

SUMMARY OF THE INVENTION

The invention provides a friction stir welding method for thin-gauge titanium-steel layered composite plates, aiming at the problems of many welding joint defects caused by fusion welding of thin-gauge titanium-steel layered composite plates, and the mechanical properties cannot meet the requirements for use.

In order to realize the connection of thin-gauge titanium-steel layered composite plates and avoid the formation of Fe-Ti intermetallic compounds, the present invention is achieved through the following technical solutions.

A friction stir welding method for a thin-gauge titanium steel layered composite plate, comprising the following steps:

In the first step, a thin-gauge titanium-steel layered composite plate is prepared by the explosive rolling composite process, and the thickness of the titanium in the composite plate is less than that of the steel;

The second step is to lighten the surface of the titanium steel layered composite board, and rigidly fix the layered composite board on the workbench. The composite board is assembled in a docking method, the titanium layer is located on the upper layer, and the same material is butted;

The third step is to select the heat input according to the size of the layered composite plate, and calculate the pressure of the shaft shoulder, the rotation speed of the stirring head and the welding speed;

The fourth step, before starting welding, drill a prefabricated welding hole at the starting position of the welding seam, the reduction amount of the shaft shoulder is in the range of 0.1~0.2mm, the stirring head rotates into the prefabricated hole, and the shaft shoulder is pressed under the action of pressure. into the surface of the composite board;

The fifth step, the stirring head rotates and stays for a period of time, and after the material is fully softened, the welding is carried out along the welding direction;

The sixth step, after completing the welding, lift the stirring head in the material to be welded and exit.

Further, in the first step, the thin-gauge titanium-steel composite plate is a layered composite plate prepared by an explosive rolling composite process, and its size specification is that the thickness of the layered composite plate is 1-10 mm, and the titanium alloy plate is located in the composite plate. The upper side of the plate, the thickness is less than the thickness of the steel plate.

Further, in the second step, during the butting process of the titanium-steel composite plates, the steel-steel butt joints and the titanium-titanium butt joints are butt jointed and rigidly fixed on the workbench.

Further, in the third step, the heat input in the friction stir welding process includes the following two parts of heat, the first part is the friction stir heat generation Q _E , and the second part is the plastic deformation heat Q _P ; the heat calculation formula is shown in the formula. (1) to formula (3),

Q=Q _E +Q _P (3)

Among them, ω is the rotating speed of the stirring head; ν is the welding speed; η _p is the heat generation coefficient of plastic deformation, 0.8 to 0.99; σ is the stress; ε _p is the plastic strain rate; V is the volume; ΔT is the time increment.

Further, in the third step, the heat input is controlled at 9 to 20 kJ/mm, the rotation speed of the stirring head is 300 to 500 r/min, the welding speed is 40 to 60 mm/min, and the reduction of the shaft shoulder is titanium alloy. Layer thickness, the amount of downward pressure between the shafts of the stirring head is 0.1 to 0.2 mm.

Further, in the fourth step, the depth of the prefabricated hole is less than the thickness of the composite board, which is equal to the thickness of the composite board minus 0.2-0.4 mm.

Further, in the fifth step, the downward insertion speed of the stirring head is 10-20 mm/min, and the rotation and residence time of the stirring head is 5-15 s.

The invention provides a friction stir welding method for thin-gauge titanium-steel layered composite plates. Compared with the prior art, its advantages are:

1. The present invention points out the optimum heat input for friction stir welding of thin-gauge titanium-steel layered composite plates. During welding, the welding heat input is selected according to the dimensional characteristics of thin-gauge titanium-steel layered composite plates, and the shoulder pressure and The reduction amount, the rotation speed of the stirring head and the welding speed can realize the effective connection of dissimilar materials of thin-gauge titanium-steel composite plates.

2. In this invention, by reasonably controlling the heat input, it is ensured that the welding temperature during the stirring process is lower than the melting point of steel and titanium, which can not only avoid shrinkage holes and slag inclusion defects during the fusion welding process, but also avoid the interaction of dissimilar materials. Fe-Ti intermetallic compound improves the quality of welded joints and realizes the connection of thin-gauge titanium-steel clad plates.

Description of drawings

1 is a schematic diagram of assembly before welding according to an embodiment of the present invention;

2 is a schematic diagram of the appearance design of a stirring head according to an embodiment of the present invention;

Fig. 3 is the schematic diagram of the pressing stage of the stirring needle according to the embodiment of the present invention;

FIG. 4 is a schematic diagram of a stir welding process according to an embodiment of the present invention.

In the figure: 1-1 is the worktable fixture, 1-2 is the plate to be welded, 1-3 is the prefabricated hole, 2-1 is the shoulder of the stirring shaft, 2-2 is the stirring needle, and 4-1 is the steel plate of the composite plate , 4-2 is the titanium alloy plate of the composite plate, 4-3 is the stirring head, 4-4 is the rotation direction, and 4-5 is the welding direction.

Detailed ways

The embodiments of the present invention are described in detail below: the present embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following implementations example.

Embodiment 1:

In the first step, a TA2/Q235 titanium-steel clad plate with a thickness of 1mm is prepared by the explosive rolling cladding process, in which the thickness of the steel is 0.8mm and the thickness of the titanium alloy is 0.2mm. Oxide film and oil stains.

In the second step, as shown in Figure 1 and Figure 4, the TA2/Q235 titanium-steel composite plates are butted together, in which the steel-steel butt joint and the titanium-titanium butt joint are rigidly fixed on the workbench.

In the third step, the heat input is 9.32kJ/mm, the rotation speed of the stirring head is 300r/min, and the welding speed is 40mm/min. The material of the stirring head is rhenium tungsten alloy. The shape of the stirring needle is cylindrical and has no thread structure. As shown in Figure 2, a stirring needle with a length of 0.6 mm and a diameter of 2 mm is selected.

The fourth step is to prepare prefabricated holes with a depth of 0.7mm and a diameter of 2mm. The stirring needle starts to rotate at a rotation speed of 300r/min, and is inserted into the prefabricated hole on the titanium steel clad plate at a speed of 10mm/min; the pressing amount of the shoulder of the stirring head is 0.1mm, and it is pressed into the titanium alloy side, as shown in Figure 3 As shown, the rotation stays for 10s, and the material heats up and softens;

In the fifth step, the stirring head is welded at a welding speed of 40mm/min, as shown in Figure 4, to keep the welding stable.

The sixth step, after the welding is completed, the shaft shoulder together with the stirring needle is lifted out of the material to be welded synchronously.

The titanium-steel composite plate is welded by the above method, and a high-strength welded joint with a tensile strength of 80% of the base material is prepared. No Ti-Fe intermetallic compounds were found in the microstructure. High quality titanium-steel clad sheet welded joints were obtained.

Example 2:

In the first step, a TA2/Q235 titanium-steel clad plate with a thickness of 1.8mm is prepared by the explosive rolling cladding process, wherein the thickness of the steel is 1.5mm, and the thickness of the titanium alloy is 0.3mm, the side of the clad plate is polished, and the surface is cleaned oxide film and oil contamination.

In the second step, as shown in Figure 1 and Figure 4, the TA2/Q235 titanium-steel composite plates are butted together, in which the steel-steel butt joint and the titanium-titanium butt joint are rigidly fixed on the workbench.

In the third step, the heat input is 13.86kJ/mm, the rotation speed of the stirring head is 400r/min, and the welding speed is 55mm/min. The material of the stirring head is rhenium tungsten alloy, and the shape of the stirring needle is cylindrical and has no thread structure. The stirring needle with a length of 1.3mm and a diameter of 3mm is selected. as shown in picture 2.

The fourth step is to prepare prefabricated holes with a depth of 1.3mm and a diameter of 3mm. The stirring needle starts to rotate at a rotation speed of 400r/min, and is inserted into the prefabricated hole on the titanium steel clad plate at a speed of 15mm/min; the pressing amount of the shoulder of the stirring head is 0.2mm, and it is pressed into the titanium alloy side, as shown in Figure 3 As shown, the rotation stops for 15s, and the material heats up and softens;

In the fifth step, the stirring head is welded at a welding speed of 55mm/min, as shown in Figure 4, to keep the welding stable.

The sixth step, after the welding is completed, the shaft shoulder together with the stirring needle is lifted out of the material to be welded synchronously.

Using the above method to weld titanium-steel clad plates avoids the interaction between steel and titanium alloy, prevents the formation of Fe-Ti intermetallic compounds, and obtains high-quality welded joints of titanium-steel clad plates.

Example 3 :

In the first step, a TA2/Q235 titanium-steel clad plate with a thickness of 6mm is prepared by an explosive rolling cladding process, wherein the thickness of the steel is 5mm and the thickness of the titanium alloy is 1mm. The side of the clad plate is polished and the oxide film on the surface is cleaned. and oil stains.

In the second step, as shown in Figure 1 and Figure 4, the TA2/Q235 titanium-steel composite plates are butted together, in which the steel-steel butt joint and the titanium-titanium butt joint are rigidly fixed on the workbench.

In the third step, the heat input is 17.53kJ/mm, the rotation speed of the stirring head is 450r/min, and the welding speed is 60mm/min. The material of the stirring head is rhenium tungsten alloy, and the shape of the stirring needle is cylindrical and has no thread structure. The stirring needle with a length of 5mm and a diameter of 4mm is selected. as shown in picture 2.

The fourth step is to prepare prefabricated holes with a depth of 5.2mm and a diameter of 4mm. The stirring needle starts to rotate at a rotation speed of 450r/min, and is inserted into the prefabricated hole on the titanium-steel composite plate at a speed of 20mm/min; the pressing amount of the shoulder of the stirring head is 0.4mm, and it is pressed into the titanium alloy side, as shown in Figure 3 As shown, the rotation stays for 20s, and the material heats up and softens;

In the fifth step, the stirring head is welded at a welding speed of 60mm/min, as shown in Figure 4, to maintain smooth welding.

The sixth step, after the welding is completed, the shaft shoulder together with the stirring needle is lifted out of the material to be welded synchronously.

Using the above method to weld titanium-steel clad plates avoids the interaction between steel and titanium alloy, prevents the formation of Fe-Ti intermetallic compounds, and obtains high-quality welded joints of titanium-steel clad plates.

Claims (7)

1. a friction stir welding method of a thin gauge titanium steel layered composite plate, is characterized in that, comprises the following steps: In the first step, the titanium-steel layered composite plate is prepared by the explosive rolling composite process, and the thickness of the titanium in the composite plate is smaller than that of the steel; The second step is to lighten the surface of the titanium steel layered composite board, and rigidly fix the layered composite board on the workbench. The composite board is assembled in a docking method, the titanium layer is located on the upper layer, and the same material is butted; The third step is to select the heat input according to the size of the layered composite plate, and calculate the pressure of the shaft shoulder, the rotation speed of the stirring head and the welding speed; The fourth step, before starting welding, drill a prefabricated welding hole at the starting position of the welding seam, the reduction amount of the shaft shoulder is in the range of 0.1~0.2mm, the stirring head rotates into the prefabricated hole, and the shaft shoulder is pressed under the action of pressure. into the surface of the composite board; The fifth step, the stirring head rotates and stays for a period of time, and after the material is fully softened, the welding is carried out along the welding direction; The sixth step, after completing the welding, lift the stirring head in the material to be welded and exit. 2. the friction stir welding method of thin gauge titanium-steel layered composite plate as claimed in claim 1, is characterized in that, in the described first step, thin gauge titanium-steel composite plate adopts the layer prepared by explosive rolling composite process The thickness of the layered composite plate is 1-10 mm, the titanium alloy plate is located on the upper side of the composite plate, and the thickness is smaller than the thickness of the steel plate. 3. the friction stir welding method of a kind of thin gauge titanium-steel laminated clad plate as claimed in claim 1, is characterized in that, in the described second step, in the butt joint process of titanium-steel clad plate, steel-steel is butted , Titanium - titanium butt, rigidly fixed on the workbench. 4. The friction stir welding method of thin gauge titanium-steel layered composite plate as claimed in claim 1, characterized in that, in the third step, the heat input in the friction stir welding process comprises the following two parts of heat, the first One part is the friction stir heat generation Q _E , and the second part is the plastic deformation heat Q _P ; the heat calculation formulas are shown in formulas (1) to (3),

Q=Q _E +Q _P (3) Among them, ω is the rotating speed of the stirring head; ν is the welding speed; η _p is the heat generation coefficient of plastic deformation, 0.8 to 0.99; σ is the stress; ε _p is the plastic strain rate; V is the volume; ΔT is the time increment. 5. The friction stir welding method of thin-gauge titanium-steel layered composite plate as claimed in claim 1, characterized in that, in the third step, the heat input is controlled at 9-20kJ/mm, and the stirring head rotates The speed is 300 to 500 r/min, the welding speed is 40 to 60 mm/min, the thickness of the titanium alloy layer is reduced by the shoulder, and the reduction between the shafts of the stirring head is 0.1 to 0.2 mm. 6. The friction stir welding method for thin-gauge titanium-steel layered composite plate as claimed in claim 1, characterized in that, in the fourth step, the depth of the prefabricated hole is less than the thickness of the composite plate, equal to the thickness of the composite plate minus 0.2 ~0.4mm. 7. The friction stir welding method of thin-gauge titanium-steel layered composite plate as claimed in claim 1, characterized in that, in the fifth step, the stirring head inserting speed is 10～20mm/min, and the stirring head rotation dwell time for 5 to 15s.

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