Titanium alloy sheet butt weld form control method

Abstract

The invention discloses a titanium alloy sheet butt weld form control method, which is characterized in that a porous material is arranged between a first sheet workpiece to be welded and a second sheet workpiece to be welded, the porosity of the porous material is controlled to be 5-20%, the sheet workpieces and the porous material are made of the same material, and welding is carried out by adopting a friction stir welding process. By the adoption of the scheme, the compactness of the welding seam can be smoothly adjusted and controlled, and flashes on the two sides of the welding seam can be effectively restrained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium alloy welding, and particularly relates to a titanium alloy sheet butt joint weld form control method. BACKGROUND

[0002] Weld form refers to the shape, size and surface structure and other characteristics of the weld in space. In the traditional technical route, the weld form is mainly controlled by adjusting the welding process parameters (including welding voltage, welding current, welding speed).

[0003] For titanium alloy butt joints, in addition to the traditional argon arc welding, the current friction stir welding technology can also be used to obtain welds with good quality. For example, the thin-walled titanium alloy sheet friction stir welding method disclosed in document CN117464161A, the titanium alloy welding joint overall uniform superplastic forming friction stir welding process disclosed in document CN112935522A, and the titanium alloy friction stir welding head and welding method disclosed in document CN107649780A. However, the tightness of the welds obtained by using the foregoing methods is almost fixed and cannot be easily controlled. In addition, when using the friction stir welding technology to perform welding, under the rotation of the stirring needle and the shaft shoulder, flash is easily generated on both sides of the weld. How to effectively suppress the generation of flash is also a problem to be solved, especially because the weld thinning and flash generation will cause part of the material to be lost, resulting in the weld tightness being significantly lower than the base material. SUMMARY

[0004] At least to solve the technical problems mentioned in the background, the application provides a titanium alloy sheet butt joint weld form control method, which adopts the following technical scheme.

[0005] A titanium alloy sheet butt joint weld form control method, a porous material is installed between the to-be-welded sheet workpiece 1 and the sheet workpiece 1, the porosity of the porous material is controlled to be 5% to 20%, the sheet workpiece and the porous material are of the same material, and the friction stir welding process is used to perform welding. Since the welding is performed after the porous material is installed between the to-be-welded sheet workpiece 1 and the sheet workpiece 1, the weld tightness can be effectively controlled during the welding process, and the weld tightness can be controlled to be almost the same as that of the base material.

[0006] In order to make the tightness of the weld better, the porosity of the porous material is controlled to be 8% to 15%. More preferably, the porosity of the porous material is controlled to be 10% to 12%.

[0007] In order to further reduce the resistance of the friction stir welding tool during the welding process, the porous material is a component made of powder raw materials by bonding and pressing into a target shape and then debinding.

[0008] Preferably, the preparation step of the porous material comprises: Step a, mixing the titanium alloy powder and the binder evenly to obtain an injection material; Step b, adding the injection material into an injection molding device to obtain a molded roughcast of a target shape by using an injection molding method; Step c, performing a debinding treatment on the obtained molded roughcast to obtain the porous material.

[0009] More preferably, during the injection molding process, the injection material is controlled at a mold pressing pressure of 5-6 MPa after being injected into the mold.

[0010] Further, in order to obtain a titanium alloy butt weld joint without thinning and with better quality, the porous material comprises a square body and a cap body which are integrally formed, the cap body is located above the square body, the height of the square body is equal to the thickness of the sheet workpiece, the cap body is wider than the square body, the width of the cap body is greater than the diameter of the shoulder of the friction stir welding tool; the bottom surface of the cap body is a plane, the top surface of the cap body is an inclined surface, the slope of the top surface of the cap body is smaller than the slope of the concave surface of the shoulder, and the width of the square body is smaller than the diameter of the lower end of the stirring pin of the friction stir welding tool; and during the friction stir welding process, the lower edge of the shoulder always penetrates into the cap body and abuts against the top surface of the sheet workpiece.

[0011] Further, the steps comprise: Step 1, preparing and cleaning the sheet workpiece to be welded and the porous material; Step 2, installing the sheet workpiece, the sheet workpiece and the porous material on the welding workbench of the friction stir welding device, the porous material is abutted between the sheet workpiece and the sheet workpiece, and the sheet workpiece and the sheet workpiece are pressed tightly; Step 3, setting the friction stir welding process parameters, setting the penetration depth of the shoulder of the friction stir welding tool, and performing the welding in an inert atmosphere environment; Step 4, after the welding is completed, removing the excess material on the surface of the weld joint.

[0012] Preferably, the wall thickness of the titanium alloy sheet workpiece is 1-3 mm.

[0013] In the present application, the weld joint form includes weld joint tightness, weld joint shape, weld joint thinning amount and weld joint flash; the titanium alloy is replaced by an aluminum alloy, a magnesium alloy, a copper material or a steel material.

[0014] Preferably, for the titanium alloy sheet workpiece with a wall thickness of 1-3 mm, the stirring pin rotates at a speed of 500-550 rpm during the welding process, and the welding travel speed is controlled at 250-350 mm / min.

[0015] Beneficial effects: by adopting the scheme of the present application, the weld tightness can be successfully regulated, the flash on both sides of the weld can be effectively inhibited, the weld thinning problem in the friction stir welding process of the titanium alloy sheet is solved, the resistance of the friction stir welding tool during the traveling process is greatly reduced, the welding process is smoother and easier, and the weld quality of the titanium alloy sheet butt joint is ensured. In the present application, the titanium alloy sheet butt weld form control is achieved by means of the porous material in cooperation with the friction stir welding technology, the weld tightness, weld shape, weld thinning amount and weld flash can be controlled, and a new technical route is provided for the titanium alloy sheet welding. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a welding state (cross section) schematic diagram in the embodiment; Figure 2 It is a porous material three-dimensional schematic diagram in the embodiment; Figure 3 It is a friction stir welding tool (cross section) schematic diagram in the embodiment; Figure 4 It is a weld cross section schematic diagram after the welding in embodiment 1 is finished; Figure 5 It is a weld cross section schematic diagram after the welding in embodiment 4 is finished. DETAILED DESCRIPTION

[0017] The technical scheme of the present application will be further described in detail through specific embodiments. The titanium alloy sheet in the present application refers to the titanium alloy plate with a thickness of not more than 3 mm.

[0018] First, the preparation method of the porous material used in embodiments 1-4 is described as follows: Step a, according to the porosity control of 10% of the required porous material, the titanium alloy powder and the binder are proportioned, then the titanium alloy powder (particle size 15-53 μm) and the binder (titanium alloy powder metallurgical binder, Nanjing Tianshi brand) are mixed uniformly to obtain the injection material; Step b, the injection material is added to the injection molding equipment, and the target shape of the molding rough blank is prepared by the injection molding method; wherein after the injection material enters the mold, the mold pressing pressure is controlled to be 5.5 Mpa, and the mold pressing time is 60 minutes; Step c, the obtained molding rough blank is subjected to a degreasing treatment (the degreasing treatment temperature and time are the prior art, and will not be described here), and the porous material with the shape as shown in Figure 2 is obtained. Embodiment 1

[0019] Combined Figures 1 to 4 as shown, a titanium alloy sheet butt weld form control method, the steps include: Step 1, prepare and clean the sheet workpieces 1 and 2 and the porous material 3, the sheet workpieces 1 and 2 and the porous material 3 are all Ti-6Al-4V titanium alloy, the size of the sheet workpieces 1 and 2 are both: length 50 cm, width 15 cm, wall thickness 1.5 mm; The method for cleaning the sheet workpieces to be welded is common knowledge in the art, which will not be described herein; The porous material 3 includes a square body 4 and a cap body 5 arranged symmetrically, the cap body 5 is located above the square body 4, the height of the square body 4 is equal to the thickness of the sheet workpiece, the cap body 5 is wider than the square body 4, the width of the cap body 5 is greater than the diameter of the shoulder 6 of the friction stir welding tool; the bottom surface of the cap body 5 is a plane, and the top surface of the cap body 5 is an inclined surface, the slope of the top surface of the cap body 5 is smaller than the slope of the concave surface in the shoulder 6 (the shoulder 6 of the friction stir welding equipment), so that the lower edge of the shoulder 6 can penetrate into the cap body 5; in this embodiment, the total length of the square body 4 is 50 cm (the length of a single porous material 3 is 10 cm, and five porous materials 3 are sequentially attached), the width of the square body 4 is 3 mm, the height of the square body 4 is 1.5 mm, the width of the cap body 5 is 9 mm, and the maximum thickness of the cap body 5 is 3 mm; Step 2, install the sheet workpieces 1 and 2 and the porous material 3 on the welding workbench 9 of the friction stir welding equipment, the porous material 3 is tightly attached between the sheet workpieces 1 and 2, and the porous material 3, the sheet workpiece 1 and the sheet workpiece 2 are simultaneously pressed and fixed; wherein the lower end diameter of the stirring pin 7 of the friction stir welding equipment is 4.5 mm, the upper end diameter of the stirring pin 7 is 6 mm, and the length of the stirring pin 7 is 7 mm; Step 3, set the friction stir welding process parameters (set the stirring pin rotation speed to 510 rpm, and the welding travel speed to 250 mm / min), move the stirring pin 7 of the friction stir welding tool to the welding starting point, control the stirring pin 7 to move downward to the target position, at this time, the lower edge of the shoulder 6 penetrates into the cap body 5 and the shoulder 6 penetrates into the low point (that is, the lower edge of the shoulder 6) just abuts the top surface of the sheet workpiece; then start the welding in an inert atmosphere (argon as the protective gas) environment; Step 4, after the welding is completed, the obtained weld is as shown in Figure 4 The excess material 8 on both sides of the weld surface is removed, and only the excess material on both sides of the weld surface needs to be removed, and then polished, which is very convenient. Example 2

[0020] A titanium alloy sheet butt joint seam form control method, referring to example 1, which is different from example 1 in that the wall thickness of sheet workpiece 1 and sheet workpiece 2 is 3mm; the width of square body 4 is 4mm, the height of square body 4 is 3mm, the width of cap body 5 is 11mm; the lower end diameter of stirring pin 7 of the friction stir welding equipment is 5mm, the upper end diameter of stirring pin 7 is 7mm; the friction stir welding process parameters are set (the stirring pin rotating speed is set to 500rpm, the welding travel speed is 280mm / min), and the obtained weld surface has no flash on both sides. Example 3

[0021] A titanium alloy sheet welding process based on weld reinforcement, referring to example 1, which is different from example 1 in that the wall thickness of sheet workpiece 1 and sheet workpiece 2 is 1mm, the height of square body 4 is 1mm, the length of stirring pin 7 is 6mm, the friction stir welding process parameters are set (the stirring pin rotating speed is set to 540rpm, the welding travel speed is 300mm / min), and the obtained weld surface has no flash on both sides.

[0022] Comparative example 1: which is different from example 1 in that the porous material 3 is omitted, the sheet workpiece 1 and the sheet workpiece 2 are directly in close contact, and the sheet workpiece 1 and the sheet workpiece 2 are always pressed tightly during the welding process, the depth of the lower edge of the shaft shoulder 6 into the sheet workpiece is 0.2mm, and the obtained weld surface has a large amount of flash on both sides.

[0023] Comparative example 2: which is different from example 2 in that the porous material 3 is omitted, the sheet workpiece 1 and the sheet workpiece 2 are directly in close contact, and the sheet workpiece 1 and the sheet workpiece 2 are always pressed tightly during the welding process, the depth of the lower edge of the shaft shoulder 6 into the sheet workpiece is 0.2mm, and the obtained weld surface has a large amount of flash on both sides.

[0024] Comparative example 3: which is different from example 3 in that the porous material 3 is omitted, the sheet workpiece 1 and the sheet workpiece 2 are directly in close contact, and the sheet workpiece 1 and the sheet workpiece 2 are always pressed tightly during the welding process, the depth of the lower edge of the shaft shoulder 6 into the sheet workpiece is 0.2mm, and the obtained weld surface has a large amount of flash on both sides.

[0025] The weld samples obtained in the examples and the comparative examples were cut, each sample had the same volume, the density of each sample was obtained, the base material density was 4.43 g / cm3, and the results showed that the weld density obtained in Example 1 was 4.428 g / cm3, the weld density obtained in Example 2 was 4.43 g / cm3, and the weld density obtained in Example 3 was 4.427 g / cm3; the weld density obtained in Comparative Example 1 was 4.42 g / cm3, the weld density obtained in Comparative Example 2 was 4.423 g / cm3, and the weld density obtained in Comparative Example 3 was 4.415 g / cm3. It can be seen that the weld tightness in the examples is controlled to be almost the same as that of the base material, and the scheme in the examples can successfully regulate / control the weld tightness.

[0026] The advancing resistance (i.e. stable advancing resistance, which is the force of the material acting on the friction stir welding tool, and the direction of the resistance is opposite to the advancing direction of the friction stir welding tool) of the friction stir welding tool in the examples and the comparative examples during uniform advancing was tested by using a pressure sensor, and the test point was located at the outer wall of the tool head 25 mm above the lower edge of the shaft shoulder, and the results showed that the stable advancing resistance of the friction stir welding tool in Example 1 was 0.74 KN, and the stable advancing resistance of the friction stir welding tool in Comparative Example 1 was 1.21 KN; the stable advancing resistance of the friction stir welding tool in Example 2 was 0.77 KN, and the stable advancing resistance of the friction stir welding tool in Comparative Example 2 was 1.81 KN; the stable advancing resistance of the friction stir welding tool in Example 3 was 0.52 KN, and the stable advancing resistance of the friction stir welding tool in Comparative Example 3 was 1.15 KN. It can be seen that the scheme in the examples significantly reduces the resistance received by the friction stir welding tool during travel, and the welding process is smoother and easier.

[0027] The thinning amount of the weld samples obtained in the examples and the comparative examples was detected, and the results showed that the welds of Examples 1-3 were not thinned, while the weld thinning amount in the comparative examples was 0.12-0.17 mm, indicating that the scheme in the examples effectively solved the weld thinning problem in the friction stir welding process of titanium alloy thin plates. After mechanical testing of the weld samples obtained in each example and the comparative example, it was found that the mechanical properties of all the welds met the use requirements.

[0028] Due to the specific technical scheme in the application, in the friction stir welding process, most of the material of the cap body 5 enters the welding seam area in the stirring process and fills the pores in the area where the square body 4 is located, thereby ensuring the welding seam quality of the titanium alloy sheet butt joint, preventing the welding seam from being thinned, and significantly reducing the resistance received by the friction stir welding tool; a small part of the material of the cap body 5 (mainly the porous material on the periphery of the shaft shoulder) is left on the lower periphery of the shaft shoulder 6, and the small part of the material of the cap body 5 cooperates with the shaft shoulder to effectively suppress the formation of flash, and this part of the material is surplus material and is easy to remove, which has the advantage of being easy to remove the excess material on the welding seam surface; even if a small amount of surplus material on the inner side of the shaft shoulder also overflows to the material edge of the cap body 5 on the lower periphery of the shaft shoulder 6, it is also easy to remove. Example 4

[0029] A titanium alloy sheet butt joint welding seam form control method, referring to any one of examples 1-4, the main difference from the previous examples is that the stirring pin 7 is controlled to move downward to the target position, at this time the lower edge of the shaft shoulder 6 penetrates into the cap body 5 and the penetration depth of the lower edge of the shaft shoulder 6 is 0.5mm higher than the top surface of the sheet workpiece, the obtained welding seam is as shown in Figure 5 , the welding seam has a 0.5mm thick reinforcing layer 10 relative to the top surface of the sheet workpiece. In this scheme, by controlling the penetration depth of the lower edge of the shaft shoulder 6, the welding seam tightness and flatness can be controlled while the welding seam thickness is controlled.

[0030] Examples 5-8 A titanium alloy sheet butt joint welding seam form control method, referring to any one of examples 1-4, the main difference from the previous examples is that the porosity of the porous material 3 is controlled to be 8%, and the thickness of the cap body 5 is adjusted adaptively.

[0031] Examples 9-12 A titanium alloy sheet butt joint welding seam form control method, referring to any one of examples 1-4, the main difference from the previous examples is that the porosity of the porous material 3 is controlled to be 10%, and the thickness of the cap body 5 is adjusted adaptively.

[0032] Examples 13-16 A titanium alloy sheet butt joint welding seam form control method, referring to any one of examples 1-4, the main difference from the previous examples is that the porosity of the porous material 3 is controlled to be 15%, and the thickness of the cap body 5 is adjusted adaptively.

[0033] Other examples, referring to any one of examples 1-4, the main difference from the previous examples is that the titanium alloy is replaced by an aluminum alloy, a magnesium alloy, a copper material or a steel material.

Claims

1. A method for controlling the morphology of a butt weld of a titanium alloy sheet, characterized by: A porous material (3) is installed between the sheet workpiece one (1) and the sheet workpiece two (2) to be welded, the porosity of the porous material (3) is controlled to be 5%~20%, the sheet workpiece and the porous material are of the same material, and the welding is implemented by using the friction stir welding process.

2. The method of titanium alloy sheet butt weld geometry control of claim 1, wherein: The porosity of the porous material (3) is controlled to be 8%~15%.

3. The method of controlling titanium alloy sheet butt weld appearance according to claim 1, wherein: The porosity of the porous material (3) is controlled to be 10%~12%.

4. The method of titanium alloy sheet butt weld geometry control of claim 1, wherein: The porous material (3) is a component made of powder raw materials by bonding, pressing into a target shape and debinding.

5. The method of titanium alloy sheet butt weld geometry control of claim 1, wherein, The preparation steps of the porous material (3) include: Step a, uniformly mix titanium alloy powder and binder to obtain injection material; Step b, add the injection material into the injection molding equipment, and use the injection molding method to obtain a molded rough blank of a target shape; Step c, debind the obtained molded rough blank to obtain the porous material (3).

6. The method of titanium alloy sheet butt weld geometry control of claim 5, wherein, During the injection molding process, the mold pressing pressure is controlled to be 5~6Mpa after the injection material enters the mold.

7. The method of controlling titanium alloy sheet butt weld appearance according to any one of claims 1-6, wherein: The porous material (3) includes a square body (4) and a cap body (5), the cap body (5) is located above the square body (4), the height of the square body (4) is equal to the thickness of the sheet workpiece, the cap body (5) is wider than the square body (4), the width of the cap body (5) is greater than the diameter of the shoulder (6) of the friction stir welding tool; the bottom surface of the cap body (5) is a plane, the top surface of the cap body (5) is an inclined surface, the slope of the top surface of the cap body (5) is smaller than the slope of the concave surface of the shoulder (6), the width of the square body (4) is smaller than the diameter of the lower end of the stirring pin (7) of the friction stir welding tool; and during the friction stir welding process, the lower edge of the shoulder (6) always penetrates into the cap body (5) and abuts against the top surface of the sheet workpiece.

8. The method of titanium alloy sheet butt weld geometry control of claim 7, wherein the steps of It includes: Step 1, prepare and clean the sheet workpiece one (1), the sheet workpiece two (2) and the porous material (3) to be welded; Step 2, install the sheet workpiece one (1), the sheet workpiece two (2) and the porous material (3) on the welding workbench of the friction stir welding equipment, the porous material (3) is abutted between the sheet workpiece one (1) and the sheet workpiece two (2), and the sheet workpiece one (1) and the sheet workpiece two (2) are pressed tightly; Step 3, set the friction stir welding process parameters, set the penetration depth of the shoulder (6) of the friction stir welding tool, and implement the welding in an inert atmosphere environment; Step 4, after the welding is completed, remove the excess material on the surface of the weld.

9. The method of titanium alloy sheet butt weld geometry control of claim 8, wherein: The wall thickness of the sheet workpiece is 1~3mm.

10. The method of titanium alloy sheet butt weld geometry control of claim 9, wherein: The weld form includes weld tightness, weld shape, weld thinning and weld flash; the titanium alloy is replaced by aluminum alloy, magnesium alloy, copper material or steel material.

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