Titanium alloy sheet welding process based on weld joint reinforcement

Abstract

The invention discloses a titanium alloy sheet welding process based on weld reinforcement. The titanium alloy sheet welding process comprises the steps that a first sheet workpiece to be welded, a first sheet workpiece and a weld reinforcement strip are prepared and cleaned; the first thin plate workpiece, the second thin plate workpiece and the welding seam reinforcing strip are installed on a welding workbench of friction stir welding equipment, and the welding seam reinforcing strip abuts against the position between the first thin plate workpiece and the second thin plate workpiece; friction stir welding process parameters are set, and welding is carried out in an inert atmosphere environment; and after welding is finished, excess materials on the surface of the weld joint are removed. The problem of weld joint thinning in the titanium alloy sheet friction stir welding process is solved, resistance borne by a friction stir welding tool in the advancing process is greatly reduced, the welding process is smoother and easier, meanwhile, the weld joint quality of a butt joint of the titanium alloy sheet is guaranteed, and the beneficial effect that excess materials on the surface of a weld joint are easily removed is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of titanium alloy sheet welding, and particularly relates to a titanium alloy sheet welding process based on weld reinforcement. BACKGROUND

[0002] For titanium alloy welding of thin-walled parts, the document CN117464161A provides a thin-walled titanium alloy sheet friction stir welding method, which comprises the following steps: setting the stirring needle rotating speed to 200r / min≤n≤300r / min, the stirring needle down pressure to 0.15mm≤d≤0.25mm, and the welding speed to 10mm / min≤v≤30mm / min; pre-processing the thin-walled titanium alloy sheet, polishing and cleaning the surface of the thin-walled titanium alloy sheet, and processing the butt joint surface of the thin-walled titanium alloy sheet to be flat; clamping the thin-walled titanium alloy sheet; immersing the working area of the welding machine in the protective gas during the welding process; welding the thin-walled titanium alloy sheet, adjusting the stirring needle to be located above the joint of the thin-walled titanium alloy sheet, starting the welding machine to weld the thin-walled titanium alloy sheet; and detecting the weld quality. The scheme adopts the friction stir welding process to weld, which can greatly reduce the temperature difference in the weld thickness, and improve the mechanical strength, tensile strength and hardness of the weld. However, there is still a significant weld thinning problem in the welding process.

[0003] More importantly, in the welding process of the titanium alloy sheet butt joint, in order to ensure the weld quality, the gap of the titanium alloy sheet butt joint needs to be controlled to be very small, and the stirring friction welding tool has a large resistance during the travel, which is not conducive to welding. Therefore, how to ensure the weld quality while reducing the welding resistance is one of the technical difficulties in the field. SUMMARY

[0004] At least to solve the technical problems mentioned in the background, the application provides a titanium alloy sheet welding process based on weld reinforcement, which adopts the following technical scheme.

[0005] A titanium alloy sheet welding process based on weld reinforcement, the steps comprising: Step 1, preparing and cleaning the sheet workpiece to be welded, sheet workpiece one and weld reinforcement strip; Step 2, installing the sheet workpiece one, sheet workpiece one and weld reinforcement strip on the welding workbench of the friction stir welding equipment, and the weld reinforcement strip is abutted between the sheet workpiece one and the sheet workpiece one; Step 3, setting the friction stir welding process parameters, and implementing the welding in an inert atmosphere environment; Step 4, after the welding is completed, removing the excess material on the surface of the weld.

[0006] Further, the preparation method of the weld reinforcement strip is as follows: Step 11, mix the titanium alloy powder and the binder evenly to obtain an injection material; Step 12, add the injection material into an injection molding device to obtain a molded rough blank in a target shape by using an injection molding method; Step 13, perform a degreasing treatment on the obtained molded rough blank to obtain a weld reinforcement strip.

[0007] Preferably, the porosity of the weld reinforcement strip is controlled to be 8%~12%.

[0008] In order to further improve the weld quality and facilitate the removal of the excess material on the surface of the weld, the weld reinforcement strip comprises an integrally formed rectangular portion and a wing portion, the wing portion is located above the rectangular portion, the height of the rectangular portion is equal to the thickness of the sheet workpiece, the wing portion is wider than the rectangular portion, and the width of the wing portion is greater than the diameter of the shaft shoulder of the friction stir welding tool.

[0009] Preferably, the bottom surface of the wing portion is a plane, the top surface of the wing portion is an inclined surface, the slope of the top surface of the wing portion is smaller than the slope of the concave surface of the shaft shoulder, and the width of the rectangular portion is smaller than the diameter of the lower end of the stirring pin of the friction stir welding tool.

[0010] In order to more easily remove the excess material on the surface of the weld, the shaft shoulder of the friction stir welding tool is inserted into the low point and abuts against the top surface of the sheet workpiece during the welding process.

[0011] Preferably, for the sheet workpiece with a wall thickness of 1~5mm, the stirring pin rotates at a speed of 500-550rpm during the welding process, and the welding travel speed is controlled to be 250~350mm / min.

[0012] Beneficial effects: The present application not only solves the weld thinning problem in the friction stir welding process of the titanium alloy sheet, but also greatly reduces the resistance received by the friction stir welding tool during the travel process, the welding process is more smooth and easy, the weld quality of the titanium alloy sheet butt joint is ensured, and the present application has the advantage of easy removal of the excess material on the surface of the weld. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a schematic diagram of the friction stir welding state (cross section) in the embodiment; Figure 2 It is a schematic diagram of the weld reinforcement strip (cross section) in the embodiment; Figure 3 It is a schematic diagram of the weld reinforcement strip (top view) in the embodiment; Figure 4 It is a schematic diagram of the friction stir welding tool (cross section) in the embodiment; Figure 5 It is a schematic diagram of the weld cross section after the welding in the embodiment. DETAILED DESCRIPTION

[0014] The technical solutions of the present application are further described in detail below through specific embodiments. The titanium alloy sheet in the present application refers to a titanium alloy plate with a thickness of not more than 3 mm. Example 1

[0015] In this embodiment, the preparation method of the weld reinforcement strip is first described as follows: Step 11, the titanium alloy powder (particle size 15-53 μm) and the binder (titanium alloy powder metallurgical binder, Nanjing Tianshi) are mixed uniformly to obtain an injection material according to the porosity control of 10% of the required weld reinforcement strip; Step 12, the injection material is added to the injection molding equipment, and the target shape of the molding roughcast is prepared by the injection molding method. After the injection material enters the mold, the mold pressing pressure is controlled to be 5.2 Mpa. Step 13, the obtained molding roughcast is subjected to a degreasing treatment (the degreasing treatment temperature and time are prior art and will not be described here), and the weld reinforcement strip as shown in Figure 2 and Figure 3 is obtained.

[0016] In combination with Figures 1 to 5 , a titanium alloy sheet welding process based on weld reinforcement is provided, and the steps include: Step 1, prepare and clean the sheet workpieces to be welded, i.e. sheet workpiece 1, sheet workpiece 2 and weld reinforcement strip 3. The sheet workpieces 1, 2 and weld reinforcement strip 3 are all Ti-6Al-4V titanium alloy of the same material. The size of the sheet workpieces 1 and 2 is: length 50 cm, width 15 cm, and wall thickness 1.5 mm. The method for cleaning the sheet workpieces to be welded is common sense in the art, and will not be described here. The weld reinforcement strip 3 includes an integrally formed rectangular portion 4 and symmetrically arranged wing portions 5. The wing portions 5 are located above the rectangular portion 4. The height of the rectangular portion 4 is equal to the thickness of the sheet workpiece. The wing portions 5 are wider than the rectangular portion 4. The width of the wing portions 5 is greater than the diameter of the shoulder 6 of the friction stir welding tool. The bottom surface of the wing portions 5 is a plane, and the top surface of the wing portions 5 is an inclined surface. The slope of the top surface of the wing portions 5 is smaller than the slope of the concave surface in the shoulder 6 of the friction stir welding equipment, so that the lower edge of the shoulder 6 can penetrate into the wing portions 5. The total length of the rectangular portion 4 is 50 cm (the length of a single weld reinforcement strip 3 is 10 cm, and five weld reinforcement strips 3 are sequentially attached). The width of the rectangular portion 4 is 3 mm, the height of the rectangular portion 4 is 1.5 mm, the width of the wing portions 5 is 9 mm, and the maximum thickness of the wing portions 5 is 3 mm. Step 2, install the sheet workpiece one 1, the sheet workpiece two 2 and the weld reinforcement strip 3 on the welding workbench 9 of the friction stir welding equipment, the weld reinforcement strip 3 is tightly pressed between the sheet workpiece one 1 and the sheet workpiece two 2, and the weld reinforcement strip 3, the sheet workpiece one 1 and the sheet workpiece two 2 are tightly fixed; wherein the diameter of the lower end of the stirring pin 7 of the friction stir welding equipment is 4.5mm, the diameter of the upper end of the stirring pin 7 is 6mm, and the length of the stirring pin 7 is 7mm; Step 3, set the friction stir welding process parameters (set the stirring pin rotation speed to 510rpm, and the welding travel speed to 250mm / 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 shaft shoulder 6 penetrates into the wing part 5 with a depth of 0.5mm, and the shaft shoulder 6 penetrates into the low point (that is, the lower edge of the shaft shoulder 6) and abuts against 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, remove the excess material 8 on the surface of the weld, which only needs to remove the excess material on both sides of the surface of the weld, and then polish, which is very convenient. Example 2

[0017] A titanium alloy sheet welding process based on weld reinforcement, referring to example 1, the difference between it and example 1 is that the wall thickness of the sheet workpiece one 1 and the sheet workpiece two 2 is 3mm, the width of the rectangular part 4 is 4mm, the height of the rectangular part 4 is 3mm, the width of the wing part 5 is 11mm, the diameter of the lower end of the stirring pin 7 of the friction stir welding equipment is 5mm, the diameter of the upper end of the stirring pin 7 is 7mm, and the friction stir welding process parameters are set (the stirring pin rotation speed is set to 500rpm, and the welding travel speed is set to 280mm / min). Example 3

[0018] A titanium alloy sheet welding process based on weld reinforcement, referring to example 1, the difference between it and example 1 is that the wall thickness of the sheet workpiece one 1 and the sheet workpiece two 2 is 1mm, the height of the rectangular part 4 is 1mm, the length of the stirring pin 7 is 6mm, and the friction stir welding process parameters are set (the stirring pin rotation speed is set to 540rpm, and the welding travel speed is set to 300mm / min).

[0019] Comparative example 1: the difference between it and example 1 is that the weld reinforcement strip 3 is omitted, the sheet workpiece one 1 and the sheet workpiece two 2 are directly tightly pressed, and the sheet workpiece one 1 and the sheet workpiece two 2 are always tightly pressed during the welding process, the depth of the lower edge of the shaft shoulder 6 penetrating into the sheet workpiece is 0.2mm.

[0020] Comparative Example 2: The difference from Example 2 is that the weld reinforcement strip 3 is omitted, the sheet workpiece 1 and the sheet workpiece 2 are directly abutted, and the sheet workpiece 1 and the sheet workpiece 2 are always pressed during the welding process, and the depth of the lower edge of the shaft shoulder 6 into the sheet workpiece is 0.2 mm.

[0021] Comparative Example 3: The difference from Example 3 is that the weld reinforcement strip 3 is omitted, the sheet workpiece 1 and the sheet workpiece 2 are directly abutted, and the sheet workpiece 1 and the sheet workpiece 2 are always pressed during the welding process, and the depth of the lower edge of the shaft shoulder 6 into the sheet workpiece is 0.2 mm.

[0022] The advancing resistance (i.e. the stable advancing resistance, which is the force of the material acting on the friction stir welding tool in the opposite direction of the advancing direction of the friction stir welding tool) of the friction stir welding tool in the uniform advancing process in the examples and the comparative examples is tested by using a pressure sensor, and the testing point is located on the outer wall of the tool head 25 mm above the lower edge of the shaft shoulder, and the results show that the stable advancing resistance of the friction stir welding tool in Example 1 is 0.74 KN, the stable advancing resistance of the friction stir welding tool in Comparative Example 1 is 1.21 KN; the stable advancing resistance of the friction stir welding tool in Example 2 is 0.77 KN, the stable advancing resistance of the friction stir welding tool in Comparative Example 2 is 1.81 KN; the stable advancing resistance of the friction stir welding tool in Example 3 is 0.52 KN, and the stable advancing resistance of the friction stir welding tool in Comparative Example 3 is 1.15 KN. It can be seen that the scheme in the examples significantly reduces the resistance of the friction stir welding tool during the advancing process, and the welding process is smoother and easier.

[0023] The thinning amount of the weld seam samples obtained in the examples and the comparative examples is detected, and the results show that the weld seams of Examples 1-3 are not thinned, while the weld seam thinning amount in the comparative examples is 0.12-0.17 mm, indicating that the scheme in the examples effectively solves the problem of weld seam thinning in the friction stir welding process of titanium alloy sheet.

[0024] Due to the adoption of the specific technical scheme in the present application, in the friction stir welding process, most of the material of the wing part 5 enters the weld seam area during the stirring process and fills the pores in the area where the rectangular part 4 is located, thereby ensuring the weld seam quality of the titanium alloy sheet butt joint, preventing weld seam thinning, and significantly reducing the resistance of the friction stir welding tool; a small part of the material of the wing part 5 remains on the periphery of the lower edge of the shaft shoulder 6, and also has the effect of inhibiting the formation of flash, and this part of the material is surplus material which is not plasticized and is easy to remove, and has the advantage of being easy to remove the excess material on the weld seam surface.

Claims

1. A weld reinforcement based titanium alloy sheet welding process characterized by the steps of The method comprises the following steps: Step 1, preparing and cleaning the sheet workpiece one (1), the sheet workpiece two (2) and the weld reinforcement strip (3); Step 2, installing the sheet workpiece one (1), the sheet workpiece two (2) and the weld reinforcement strip (3) on the welding workbench of the friction stir welding equipment, and the weld reinforcement strip (3) is abutted between the sheet workpiece one (1) and the sheet workpiece two (2); Step 3, setting the friction stir welding process parameters, and performing welding in an inert atmosphere environment; Step 4, after the welding is completed, removing the excess material on the weld surface.

2. The titanium alloy sheet welding process of claim 1, wherein, The preparation method of the weld reinforcement strip (3) is as follows: Step 11, uniformly mixing the titanium alloy powder and the binder to obtain an injection material; Step 12, adding the injection material into an injection molding equipment, and using an injection molding method to obtain a molded rough blank with a target shape; Step 13, performing a degreasing treatment on the obtained molded rough blank to obtain the weld reinforcement strip (3).

3. The titanium alloy sheet welding process of claim 1 or 2, wherein: The porosity of the weld reinforcement strip (3) is controlled to be 8% to 12%.

4. The titanium alloy sheet welding process of claim 3, wherein: The weld reinforcement strip (3) comprises an integrally formed rectangular portion (4) and a wing portion (5), the wing portion (5) is located above the rectangular portion (4), the height of the rectangular portion (4) is equal to the thickness of the sheet workpiece, the wing portion (5) is wider than the rectangular portion (4), and the width of the wing portion (5) is greater than the diameter of the shoulder (6) of the friction stir welding tool.

5. The titanium alloy sheet welding process of claim 4, wherein: The bottom surface of the wing portion (5) is a plane, the top surface of the wing portion (5) is an inclined surface, the slope of the top surface of the wing portion (5) is smaller than the slope of the inner concave surface of the shoulder (6), and the width of the rectangular portion (4) is smaller than the diameter of the lower end of the stirring pin (7) of the friction stir welding tool.

6. The titanium alloy sheet welding process of claim 5, wherein: During the welding process, the shoulder (6) of the friction stir welding tool is inserted into the low point and abuts against the top surface of the sheet workpiece.

7. The titanium alloy sheet welding process of claim 6, wherein: For the sheet workpiece with a wall thickness of 1 to 5 mm, the stirring pin (7) rotates at a speed of 500-550 rpm during the welding process, and the welding travel speed is controlled to be 250-350 mm / min.

Images