A manufacturing method for improving the weld strength of a titanium alloy welded part

Abstract

A kind of manufacturing method for improving the strength of titanium alloy welded joint weld, titanium alloy welded joint after vacuum annealing treatment is heated to 900-1100 DEG C, constant temperature compression deformation is carried out, compression deformation amount is 20-50%, and deformation speed is 0.01-0.02mm / s;The titanium alloy welded joint is the titanium alloy plate material welded well;The obtained material is cooled to 500-550 DEG C, constant temperature compression deformation is carried out again, compression deformation amount is 3-5%, and deformation speed is 0.01-0.02mm / s, then air cooling to room temperature, then in turn carry out solution treatment and aging treatment.The present application can improve the uniformity of welded joint structure and mechanical properties, and enhance its service stability.

Description

Technical Field

[0001] This technology belongs to the field of titanium alloy manufacturing, and specifically relates to a manufacturing method for improving the weld strength of titanium alloy welded parts. Background Technology

[0002] Titanium alloys have poor weldability, and the microstructure of welded joints is extremely sensitive to welding processes and environments. They are prone to cracking under extreme working conditions, leading to serious service accidents. A typical example is TC4, an α+β dual-phase alloy with excellent properties such as high strength, high toughness, and corrosion resistance. However, due to the influence of welding processes and heat dissipation conditions, the microstructure and morphology of different zones within the welded joint are very complex. If the microstructure of the welded joint is uneven, microcracks are easily generated during loading. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide a manufacturing method for improving the weld strength of titanium alloy welded parts, so as to improve the uniformity of the weld joint structure and mechanical properties, and enhance its service stability.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A manufacturing method for improving the weld strength of titanium alloy welded parts includes the following steps:

[0006] Step 1: Heat the vacuum-annealed titanium alloy welded parts to 900-1100℃ and perform isothermal compression deformation. The compression deformation amount is 20-50%, and the deformation speed is 0.01-0.02mm / s. The titanium alloy welded parts are welded titanium alloy plates.

[0007] Step 2: Cool the material obtained in Step 1 to 500-550℃ and perform isothermal compression deformation again. The compression deformation amount is 3-5% and the deformation speed is 0.01-0.02mm / s.

[0008] Step 3: Cool the material obtained in Step 2 to room temperature, and then perform solution treatment and aging treatment in sequence.

[0009] In one embodiment, the thickness of the welded titanium alloy plate is 15-30mm. Before vacuum annealing, the weld and surrounding area are trimmed and ground to ensure the smoothness of the base material and the weld.

[0010] In one embodiment, the vacuum annealing conditions are: 550-650℃, held for 1-2 hours.

[0011] In one embodiment, the titanium alloy welded part after vacuum annealing is air-cooled to room temperature, and then its surface is polished to remove the oxide layer generated during the annealing and cooling process.

[0012] In one embodiment, in step 1, when the deformation amount per pass exceeds 20%, a multi-pass isothermal deformation process is adopted, wherein the isothermal furnace is filled with argon gas as a protective gas.

[0013] In one embodiment, step 3 involves air-cooling the surface to room temperature and then polishing it to remove the oxide layer.

[0014] In one embodiment, the solution treatment conditions are: holding at 920-980℃ in a vacuum furnace for 0.5-1.5 hours.

[0015] In one embodiment, the aging treatment conditions are: 510-540℃, 2-8h.

[0016] In one embodiment, the titanium alloy is TC4.

[0017] Compared with existing technologies, the titanium alloy welded parts manufactured using the method of this invention have an ultimate tensile strength of approximately 975 MPa at the weld joint, which is about 170 MPa higher than that of welded parts in the same heat-treated state without isothermal compression. Furthermore, the weld strength of the titanium alloy welded parts manufactured using the method of this invention significantly exceeds that of the surrounding base material, which can greatly reduce the likelihood of ultimate cracking in equipment using this titanium alloy during service. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the isothermal compression structure of the present invention.

[0019] Figure 2 This is a schematic diagram comparing the performance of the embodiments of the present invention with that of the initial alloy and ordinary weld, wherein (a) is a comparison of tensile properties and (b) is the elongation at break.

[0020] The components are: 1-frame, 2-insulation box, 3-compressor upper pressure block, 4-titanium alloy welded parts, 5-lower pressure block, 6-frame, 7-control system, 8-operating system. Detailed Implementation

[0021] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0022] The present invention provides a plastic manufacturing method for improving the weld strength of titanium alloy welded parts, which employs a combined process of isothermal plastic forming and heat treatment, and may specifically include the following steps:

[0023] Step 1: Take the titanium alloy welded component, typically a welded titanium alloy sheet, with a thickness of approximately 15-30mm. Repair and grind the weld and surrounding area to ensure the smoothness of both the base material and the weld. In this embodiment, the titanium alloy is specifically TC4.

[0024] Step 2: In order to reduce the hydrogen content of the titanium alloy surface layer, eliminate the possibility of hydrogen embrittlement during the welding process, and reduce the influence of residual stress on the welding process, the titanium alloy welded parts are placed in a vacuum furnace for vacuum annealing at 550-650℃. After reaching the temperature, they are held at that temperature for 1-2 hours, and then air-cooled to room temperature.

[0025] Step 3: Polish the surface of the annealed welded parts to remove the oxide layer generated during the annealing and cooling process.

[0026] The first to third steps described above are optional steps of the present invention. The present invention can be directly executed from the fourth step as follows.

[0027] Step 4: Place the titanium alloy welded parts in a vacuum furnace at 900-1100℃ and heat them for 0.5-1 hour.

[0028] Step 5: Remove the titanium alloy welded parts (900-1100℃) from the vacuum furnace and immediately place them in a thermostatic compressor for thermostatic compression deformation. The transfer time should be less than 5 seconds. Compression deformation can be performed by forging, rolling, etc. The total deformation amount should be set to 20-50%, and the deformation speed should be 0.01-0.02 mm / s. When the deformation amount in a single pass exceeds 20%, a multi-pass thermostatic deformation process is required. Argon gas is used as a protective gas in the thermostatic furnace.

[0029] The isothermal compression in the fourth and fifth steps can reduce defects such as stress and voids generated during the welding process, promote the uniform distribution of elements in different zones, improve the bonding strength between the weld and the base metal interface, and improve the plasticity and ductility of the material through high-temperature deformation.

[0030] A isothermal compression structure of the present invention, as follows Figure 1 As shown, the system includes an upper frame 1, an insulation box 2, an upper compressor block 3, a lower compressor block 5, a lower frame 6, a control system 7, and an operating system 8. The upper compressor block 3 and the lower compressor block 5 are placed in the insulation box 2. The lower compressor block 5 is installed on the lower frame 6. The upper compressor block 3 is connected to the upper frame 1 through a connecting rod. The control system 7 acts on the upper frame 1 to drive the upper compressor block 3 to move up and down. The titanium alloy welded part 4 is clamped between the upper compressor block 3 and the lower compressor block 5. Compression is completed by the movement of the upper compressor block 3.

[0031] Step 6: After compression, turn off the power to the heating furnace and cool the sample with the furnace to 500-550℃.

[0032] Step 7: After reaching the set temperature, close the furnace door and perform isothermal compression again. The compression deformation is 3-5%, and the deformation speed is 0.01-0.02 mm / s.

[0033] The isothermal compression in steps six and seven can further eliminate welding defects, promote grain refinement in and around the weld area, improve material strength and toughness, and further enhance the uniformity of the material's microstructure.

[0034] Therefore, this invention refines the grains in the fusion zone and breaks down the coarse second phase through isothermal compression (compression processes such as rolling and forging), reducing stress concentration caused by coarse crystals, while further improving the degree of matrix recrystallization through appropriate deformation temperature.

[0035] Step 8: After compression, remove the sample and air-cool it to room temperature.

[0036] Step 9: Polish the sample surface to remove the oxide layer.

[0037] Step 10: Place the sample in a vacuum furnace for solution treatment at 920-980℃, and heat and hold at that temperature for 0.5-1.5 hours.

[0038] Step 11: After solution treatment, the sample is cooled in the furnace to 510-540℃ and then subjected to aging treatment for 2-8 hours.

[0039] Through heat treatment steps 10 and 11, residual stress in the weld can be reduced, solute dissolution can be promoted, and spheroidization of the second phase can be accelerated, thereby further reducing the stress concentration caused by the weld during subsequent service. Furthermore, the weld strength can be further improved by strengthening phase precipitation.

[0040] Step 12: After aging is complete, remove the sample and air-cool it to room temperature.

[0041] Step 13: Polish the sample surface to remove the oxide layer.

[0042] After adopting this manufacturing method, the weld grains are significantly refined, the coarse secondary phases are broken and evenly distributed, a large number of needle-like strengthening phases are precipitated in the matrix, and the weld strength exceeds the strength of the base material, which greatly reduces the cracking behavior of titanium alloy equipment welds during harsh service.

[0043] The following is a specific embodiment of the present invention.

[0044] Example 1

[0045] A plastic manufacturing method for improving the weld strength of titanium alloy welded parts includes the following steps:

[0046] Step 1: Take the welded TC4 titanium alloy plate, which is about 30mm thick, and repair and grind the weld and surrounding area to ensure the smoothness of the base material and the weld.

[0047] Step 2: Place the titanium alloy welded parts in a vacuum furnace for vacuum annealing at 650℃, hold at that temperature for 1 hour, and then air cool to room temperature.

[0048] Step 3: Polish the surface of the annealed welded parts to remove the oxide layer generated during the annealing and cooling process.

[0049] Step 4: Place the titanium alloy welded parts in a vacuum furnace at 1050℃ and heat them for 0.5 hours.

[0050] Step 5: After removing the titanium alloy welded sheet from the vacuum furnace, immediately place it in a constant temperature rolling mill for rolling deformation. The transfer time is less than 5 seconds, the deformation speed is 0.01 mm / s, the deformation amount of the first pass is 10%, the deformation amount of the second pass is 15%, the deformation amount of the third pass is 8%, and the total deformation amount is set to 30%. Argon gas is used as a protective gas in the constant temperature furnace.

[0051] Step 6: After compression, turn off the power to the heating furnace and cool the sample with the furnace to 520°C.

[0052] Step 7: After reaching the set temperature, close the furnace door and perform isothermal compression again. The compression deformation is 3.5% and the deformation rate is 0.01 mm / s.

[0053] Step 8: After compression, remove the sample and air-cool it to room temperature.

[0054] Step 9: Polish the sample surface to remove the oxide layer.

[0055] Step 10: Place the sample in a vacuum furnace for solution treatment at 965℃, and heat and hold at that temperature for 1 hour.

[0056] Step 11: After solution treatment, the sample is cooled to 535℃ in the furnace and then subjected to aging treatment for 4 hours.

[0057] Step 12: After aging is complete, remove the sample and air-cool it to room temperature.

[0058] Step 13: Polish the sample surface to remove the oxide layer.

[0059] refer to Figure 2 In (a) and (b), after the method of this embodiment, the weld strength of TC4 titanium alloy increased from the original (i.e., before the treatment of this embodiment) 862.5 MPa to 1170.6 MPa, and the elongation at break also increased by about 48%. In addition, the weld strength is higher than that of the base material, exceeding the base material by about 80 MPa, indicating that the present invention can significantly enhance the welding strength of titanium alloy welds.

[0060] Example 2

[0061] A plastic manufacturing method for improving the weld strength of titanium alloy welded parts includes the following steps:

[0062] Step 1: Take the welded TC4 titanium alloy plate, which is about 30mm thick, and repair and grind the weld and surrounding area to ensure the smoothness of the base material and the weld.

[0063] Step 2: Place the titanium alloy welded parts in a vacuum furnace for vacuum annealing at 550℃, hold at that temperature for 1.5 hours, and then air cool to room temperature.

[0064] Step 3: Polish the surface of the annealed welded parts to remove the oxide layer generated during the annealing and cooling process.

[0065] Step 4: Place the titanium alloy welded parts in a 900℃ vacuum furnace and heat them for 0.5 hours.

[0066] Step 5: After removing the titanium alloy welded sheet from the vacuum furnace, immediately place it in a constant temperature rolling mill for rolling deformation. The transfer time is less than 5 seconds, the deformation speed is 0.01 mm / s, the deformation amount of the first pass is 12%, the deformation amount of the second pass is 15%, the deformation amount of the third pass is 6%, and the total deformation amount is set to 30%. Argon gas is used as a protective gas in the constant temperature furnace.

[0067] Step 6: After compression, turn off the power to the heating furnace and cool the sample with the furnace to 500°C.

[0068] Step 7: After reaching the set temperature, close the furnace door and perform isothermal compression again. The compression deformation is 5% and the deformation rate is 0.02 mm / s.

[0069] Step 8: After compression, remove the sample and air-cool it to room temperature.

[0070] Step 9: Polish the sample surface to remove the oxide layer.

[0071] Step 10: Place the sample in a vacuum furnace for solution treatment at 980℃, and heat and hold it in the furnace for 1 hour.

[0072] Step 11: After solution treatment, the sample is cooled to 540℃ in the furnace and then subjected to aging treatment for 4 hours.

[0073] Step 12: After aging is complete, remove the sample and air-cool it to room temperature.

[0074] Step 13: Polish the sample surface to remove the oxide layer.

[0075] refer to Figure 2 In (a) and (b), after the method of this embodiment, the tensile properties are slightly lower than those of Example 1, but still significantly exceed the weld strength before treatment, while the elongation at break is significantly improved compared to Example 1.

[0076] Example 3

[0077] A plastic manufacturing method for improving the weld strength of titanium alloy welded parts includes the following steps:

[0078] Step 1: Take the welded TC4 titanium alloy plate, which is about 25mm thick, and repair and grind the weld and surrounding area to ensure the smoothness of the base material and the weld.

[0079] Step 2: Place the titanium alloy welded parts in a vacuum furnace for vacuum annealing at 600℃, hold at that temperature for 1 hour, and then air cool to room temperature.

[0080] Step 3: Polish the surface of the annealed welded parts to remove the oxide layer generated during the annealing and cooling process.

[0081] Step 4: Place the titanium alloy welded parts in the vacuum furnace of the constant temperature forging press and heat them to 900℃, and keep them at that temperature for 0.5 hours.

[0082] Step 5: The titanium alloy welded sheet metal is forged and compressed at a rate of 0.01 mm / s, with the total deformation set at 45% and the deformation rate at 0.02 mm / s. Argon gas is used as a protective gas in the constant-temperature furnace.

[0083] Step 6: After compression, turn off the power to the heating furnace and cool the sample with the furnace to 500°C.

[0084] Step 7: After reaching the set temperature, perform isothermal compression again, with a compression deformation of 5% and a deformation rate of 0.01 mm / s.

[0085] Step 8: After compression is complete, turn off the power to the heating furnace and allow it to cool to room temperature.

[0086] Step 9: Polish the sample surface to remove the oxide layer.

[0087] Step 10: Place the sample in a vacuum furnace for solution treatment at 950℃, and heat and hold at that temperature for 0.8 hours.

[0088] Step 11: After solution treatment, the sample is cooled to 510℃ in the furnace and then subjected to aging treatment for 4 hours.

[0089] Step 12: After aging is complete, remove the sample and air-cool it to room temperature.

[0090] Step 13: Polish the sample surface to remove the oxide layer.

[0091] refer to Figure 2In (a) and (b), after treatment using the method of this embodiment, the tensile properties and elongation at break are lower than those of Examples 1 and 2, but still significantly higher than the weld strength before treatment. In this embodiment, the weld strength of TC4 titanium alloy is increased by approximately 262 MPa compared to the original (i.e., before treatment in this embodiment), and the elongation at break also exceeds that of the initial weld, indicating that the present invention can significantly enhance the welding strength of titanium alloy welds.

Claims

1. A manufacturing method for improving the weld strength of titanium alloy welded parts, characterized in that, Includes the following steps: Step 1: Heat the vacuum-annealed titanium alloy welded parts to 900-1100℃ and perform isothermal compression deformation. The compression deformation amount is 20-50%, and the deformation speed is 0.01-0.02mm / s. The titanium alloy welded parts are welded titanium alloy plates, wherein the titanium alloy is TC4. When the single-pass deformation amount exceeds 20%, a multi-pass isothermal deformation process is adopted. Argon gas is used as a protective gas in the isothermal furnace. The vacuum annealing conditions are: 550-650℃, holding for 1-2 hours. Step 2: Cool the material obtained in Step 1 to 500-550℃ and perform isothermal compression deformation again. The compression deformation amount is 3-5% and the deformation speed is 0.01-0.02mm / s. Step 3: Cool the material obtained in Step 2 to room temperature, and then perform solution treatment and aging treatment in sequence. The conditions for solution treatment are: heat treatment at 920-980℃ in a vacuum furnace for 0.5-1.5h, and the conditions for aging treatment are: 510-540℃ for 2-8h.

2. The manufacturing method for improving the weld strength of titanium alloy welded parts according to claim 1, characterized in that, The welded titanium alloy plate has a thickness of 15-30mm. Before vacuum annealing, the weld and surrounding area are trimmed and ground to ensure the smoothness of the base material and the weld.

3. The manufacturing method for improving the weld strength of titanium alloy welded parts according to claim 1, characterized in that, After vacuum annealing, the titanium alloy welded parts are air-cooled to room temperature, and then their surfaces are polished to remove the oxide layer generated during the annealing and cooling process.

4. The manufacturing method for improving the weld strength of titanium alloy welded parts according to claim 1, characterized in that, In step 3, the surface is air-cooled to room temperature and then polished to remove the oxide layer.

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