Method, product and device for eliminating welding pores of titanium alloy lock bottom structural member

Abstract

The invention relates to the technical field of elimination of air hole defects of weldments, in particular to a method, a product and a device for eliminating welding air holes of a titanium alloy lock bottom structural component, the device comprises a laser device, a TIG welding device, a synchronous thermal field device and a titanium alloy lock bottom structural component substrate, and the laser device comprises a laser device, a laser welding head and an upper computer. The upper computer, the laser and the laser welding head are connected in sequence; the TIG welding device comprises a TIG welding gun, a TIG welding power source and an argon bottle, and the argon bottle, the TIG welding power source and the TIG welding gun are sequentially connected. By adopting the laser TIG composite welding technology under the assistance of the synchronous thermal field, the welding pore defect of the titanium alloy lock bottom structural part is eliminated, and the pore defect is eliminated when the titanium alloy lock bottom structural part is welded by performing pre-welding heating and synchronous heating during welding on the substrate in combination with the synchronous thermal field technology, so that the pore tendency of a welding joint is reduced, and the welding quality of the titanium alloy lock bottom structural part is improved. And the mechanical property of the titanium alloy lock bottom structural part joint is improved.

Description

Technical Field

[0001] The invention relates to the technical field of eliminating weld porosity defects, and in particular to a method, a product and a device for eliminating welding porosity of a titanium alloy lock bottom structural part. Background Art

[0002] With the development of modern industry, the demand for lightweight and high-performance products in the aerospace field is becoming more and more urgent. At present, key aerospace components such as engine blades and space probe tanks need to serve in various complex working conditions, which puts higher requirements on material properties and service life. Titanium alloys have gradually become the key application materials for aerospace components due to their excellent material properties. However, since titanium alloys are easily oxidized, they tend to form pores during welding, which seriously affects the strength and life of the joints. Therefore, it is very necessary to carry out research on the weldability of titanium alloys.

[0003] The lock bottom structure of the detector tank is one of the key components of the detector. In order to meet the lightweight and high-performance design, most of them use titanium alloy as the matrix. At present, the titanium alloy lock bottom structure mainly relies on vacuum electron beam welding, which greatly increases the manufacturing cost of the product; at the same time, due to the structural characteristics of the pad in the lock bottom structure, welding defects such as pores, inclusions and unfusion are easy to appear in the pad area during welding, affecting the mechanical properties of the joint; affected by the easy oxidation of titanium alloy itself, pore defects are easy to form during welding, which greatly affects the performance of the joint and has a decisive influence on the life of the detector. In order to solve the welding problem of the titanium alloy lock bottom structure of the detector tank, it is proposed to use pulse TIG-laser composite welding to weld the titanium alloy lock bottom structure of the detector tank, and at the same time use synchronous thermal field for assistance. With the help of the composite effect of synchronous thermal field technology and pulse frequency, the welding pores are eliminated, which effectively reduces the pore tendency of the joint, and provides a new solution for obtaining reliable welding joints of the lock bottom structure of the detector tank. Summary of the invention

[0004] The present invention provides a method, product and device for eliminating welding pores of titanium alloy lock bottom structural parts, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problem of easy formation of pore defects in vacuum electron beam welding of existing titanium alloy lock bottom structural parts.

[0005] To solve the above problems, one of the technical solutions of the present invention is achieved in the following manner: A method for eliminating welding pores of titanium alloy lock bottom structural parts, comprising: Set the temperature of the synchronous heating plate to 600K, and set the pulse TIG welding pulse frequency to 250Hz. After the parameters are set, the titanium alloy lock bottom structure is heated by the synchronous heating plate so that the temperature of the titanium alloy lock bottom structure is consistent with the heating temperature set by the synchronous heating plate to form a synchronous heat field, and the titanium alloy lock bottom structure is welded using the set pulse frequency. During the welding process, the titanium alloy lock bottom structure is heated in real time using the synchronous heat field to eliminate the welding pores of the titanium alloy lock bottom structure.

[0006] The above-mentioned setting of the pulse frequency of pulse TIG welding includes the following steps: The titanium alloy lock bottom structure is welded using different pulse frequencies; X-ray flaw detection was performed on titanium alloy lock bottom structural parts after welding at different pulse frequencies to detect the porosity after welding; The pulse frequency corresponding to the titanium alloy lock bottom structure with the least pore defects is determined as the set pulse frequency.

[0007] The above also includes processing the titanium alloy lock bottom structure before heating, wherein the processing process includes: The titanium alloy lock bottom structure is polished and fixed; wherein the titanium alloy lock bottom structure comprises a docking plate and a pad, the docking plate is placed on the pad and tightened with a clamp.

[0008] The above also includes pore elimination, wherein the elimination process includes: The force of the pores in the molten pool is shown as follows: , in, F h For the joint efforts, F h When >0, the pores escape to the surface of the molten pool. F h When <0, stomatal escape is inhibited; F for buoyancy; F t The thrust generated by the molten pool flow; F g is gravity; F d It is the viscosity of liquid metal.

[0009] The second technical solution of the present invention is achieved in the following way: a device for eliminating welding pores of titanium alloy lock bottom structural parts, comprising a laser device, a TIG welding device, a synchronous thermal field device and a titanium alloy lock bottom structural part substrate, the laser device comprising a laser, a laser welding head and a host computer, the host computer, the laser and the laser welding head are connected in sequence; the TIG welding device comprises a TIG welding gun, a TIG welding power supply and an argon gas cylinder, the argon gas cylinder, the TIG welding power supply and the TIG welding gun are connected in sequence; the synchronous thermal field device comprises a synchronous heating plate and a temperature controller, the temperature controller is connected to the synchronous heating plate; the titanium alloy lock bottom structural part substrate is fixed on the synchronous heating plate, the titanium alloy lock bottom structural part substrate comprises a pad and two docking plates, the pad is arranged between the two docking plates.

[0010] The angle between the above-mentioned TIG welding gun and the titanium alloy lock bottom structural component substrate is 40°; the distance between the tungsten tip of the TIG welding gun and the center of the laser beam spot emitted by the laser welding head is 6 mm; the distance between the tungsten tip of the TIG welding gun and the titanium alloy lock bottom structural component substrate is 5 mm.

[0011] The third technical solution of the present invention is achieved in the following way: a titanium alloy lock bottom structural component welding product, which is prepared by a method for eliminating welding pores of a titanium alloy lock bottom structural component.

[0012] The present invention eliminates the welding porosity defects of titanium alloy lock bottom structural parts by adopting laser TIG composite welding technology assisted by synchronous thermal field, adopts laser and TIG arc composite heat source for welding, and uses pulsed TIG arc to intervene in the fluidity of the molten pool (that is, the pulsed TIG arc introduces pulse current, and the periodic action of the pulse current acts on the molten pool area, causing the fluidity of the molten pool to change, thereby intervening in the fluidity of the molten pool). Combined with the synchronous thermal field technology, the synchronous heating plate is heated before welding and synchronously heated during welding, so as to eliminate the porosity defects when welding the titanium alloy lock bottom structural parts, thereby reducing the porosity tendency of the welded joint, improving the mechanical properties of the joints of the titanium alloy lock bottom structural parts, and obtaining titanium alloy lock bottom structural parts with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the device structure of Example 4 of the present invention.

[0015] Figure 2 This is a schematic structural diagram of the titanium alloy lock bottom structural component substrate in Example 4 of the present invention.

[0016] Figure 3 This is a schematic diagram of eliminating welding porosity defects of a titanium alloy lock bottom structure in Example 1 of the present invention.

[0017] Figure 4 This is a diagram of X-ray flaw detection results of the titanium alloy lock bottom structure under different pulse frequencies in Example 2 of the present invention.

[0018] Figure 5 This is a diagram showing the X-ray flaw detection results of the titanium alloy lock bottom structure under the action of the synchronous thermal field in Example 2 of the present invention.

[0019] Figure 6 This is a comparison chart of the tensile test of the titanium alloy lock bottom structure in Example 3 of the present invention.

[0020] In the figure: 1-laser, 2-laser welding head, 3-host computer, 4-TIG welding gun, 5-TIG welding power supply, 6-argon gas bottle, 7-synchronous heating plate, 8-temperature controller, 9-titanium alloy lock bottom structural member substrate, 10-backing plate, 11-docking plate, 12-pore one, 13-pore two, 14-pore three. DETAILED DESCRIPTION

[0021] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0022] Embodiment 1: The embodiment of the present invention discloses a method for eliminating welding pores of a titanium alloy lock bottom structural member, comprising: Set the temperature of the synchronous heating plate 7 to 600K, set the pulse TIG welding pulse frequency to 250Hz, the peak current to 90A, the base current to 30A, the laser power to 1500W, and the welding speed to 300mm / min; after the parameters are set, the titanium alloy lock bottom structure is heated by the synchronous heating plate 7, so that the temperature of the titanium alloy lock bottom structure is consistent with the heating temperature set by the synchronous heating plate 7, forming a synchronous thermal field, and the titanium alloy lock bottom structure is welded using the set pulse frequency. During the welding process, the titanium alloy lock bottom structure is heated in real time using the synchronous thermal field to eliminate the welding pores of the titanium alloy lock bottom structure.

[0023] Among them, by setting the process parameter combination of peak current to 90A, base current to 30A, laser power to 1500W, and welding speed to 300mm / min, and by matching this parameter with the set temperature of the synchronous heating plate 7 and the set pulse frequency, the welding process has better stability, the weld is formed evenly, and the welding quality meets the expected standards.

[0024] Wherein, setting the pulse frequency of pulse TIG welding includes the following steps: The titanium alloy lock bottom structure is welded using different pulse frequencies; X-ray flaw detection was performed on titanium alloy lock bottom structural parts after welding at different pulse frequencies to detect the porosity after welding; The pulse frequency corresponding to the least porosity defect is determined as the set pulse frequency.

[0025] The method further includes treating the titanium alloy lock bottom structure before heating, wherein the treatment process includes: The titanium alloy lock bottom structural parts are polished and fixed.

[0026] Among them, it also includes pore elimination, wherein the elimination process includes: The force of the pores in the molten pool is shown as follows: ,

[0027] in, F h For the joint efforts, F h When >0, the pores escape to the surface of the molten pool. F h When <0, the air venting is suppressed; F is the buoyancy; F t The thrust generated by the molten pool flow; F g is gravity; F d It is the viscosity of liquid metal.

[0028] In the molten pool, the pores are mainly affected by gravity. F g , buoyancy F, thrust generated by molten pool flow F t and liquid metal adhesion F d The gravity and liquid metal viscosity act as hindering forces to inhibit the pores from overflowing, and the pore buoyancy promotes the pores to overflow to the surface of the molten pool. The thrust generated by the molten pool flow is mainly affected by the fluidity of the molten pool. Under different flow modes, the effects on the pores are different; Figure 3 As shown, when the pore is located at the bottom of the molten pool, that is, at the position of pore 12, it is mainly affected by the laser heat source. At this time, the pore is pushed upward, and combined with the buoyancy, the pore moves upward (to the surface of the molten pool). When the pore is located at the position of pore 2 13, it is affected by the arc and is pushed obliquely upward. When the thrust is large, the pore moves toward the middle area of ​​the molten pool. When the pore reaches the position of pore 3 14, the force that causes the pore to escape upward is the thrust generated by the buoyancy and the flow of the molten pool. When the combined force of gravity and the viscosity of the liquid metal is less than the combined force of the buoyancy and the thrust generated by the flow of the molten pool, the pore escapes to the surface and finally escapes from the molten pool.

[0029] Therefore, under the action of pulse frequency plus synchronous heat field, the pulse frequency increases the fluidity of the middle and bottom areas of the molten pool. Under the action of the synchronous heat field, it not only increases the fluidity of the molten pool, but also keeps the fluidity of the molten pool unchanged for a longer time, intervenes in the solidification of the molten pool, increases the time for pores to escape, and plays a decisive role in eliminating pores.

[0030] In summary, the present invention eliminates the welding porosity defects of titanium alloy lock bottom structural parts by adopting laser TIG composite welding technology assisted by synchronous thermal field, adopts laser and TIG arc composite heat source for welding, and uses pulsed TIG arc to intervene in the fluidity of the molten pool (that is, the pulsed TIG arc introduces pulse current, and the periodic action of the pulse current acts on the molten pool area, causing the fluidity of the molten pool to change, thereby intervening in the fluidity of the molten pool). Combined with the synchronous thermal field technology, the synchronous heating plate 7 is heated before welding and synchronously heated during welding, so as to eliminate the porosity defects when welding the titanium alloy lock bottom structural parts, thereby reducing the porosity tendency of the welded joint, improving the mechanical properties of the joints of the titanium alloy lock bottom structural parts, and obtaining titanium alloy lock bottom structural parts with excellent performance.

[0031] Embodiment 2: The embodiment of the present invention discloses a welding method in which the temperature of the synchronous heating plate 7 is 600K and the pulse TIG welding pulse frequency is 250Hz, comprising the following steps: S101, turn on the power of laser 1, adjust the laser welding head 2, wipe the lens in the laser welding head 2, turn on the host computer 3, set the laser power and welding speed, where the laser power is set to 1500W and the welding speed is 300mm / min; S102, turn on the TIG welding power source 5, adjust the pulse TIG welding composite welding parameters, wherein the peak current is set to 90A, the base current is set to 30A, and the duty cycle is 50%, and the titanium alloy lock bottom structure is welded by adjusting the pulse frequency; turn on the argon gas bottle 6, and set the flow rate of the shielding gas during welding to 15L / min; S103, setting the temperature of the synchronous heating plate 7 to 600K, and adjusting the position of the synchronous heating plate 7; S104, setting the pulse frequency of pulse TIG welding to 250 Hz; S105, grinding and fixing the titanium alloy lock bottom structure; wherein the titanium alloy lock bottom structure substrate 9 includes a docking plate 11 and a backing plate 10, the docking plate 11 is placed on the backing plate 10, and is tightened with a clamp, so that the middle area of ​​the backing plate 10 and the docking plate 11 are close to avoid gaps; S106, adjust the position of the tungsten electrode tip and the laser heat source, move the TIG welding gun 4 and the laser welding head 2 to the left side of the titanium alloy lock bottom structure, and adjust the laser inclination angle to prevent the material reflection from damaging the laser head; S107, turn on the temperature controller 8, heat the titanium alloy lock bottom structure, make the temperature of the titanium alloy lock bottom structure consistent with the heating temperature set by the synchronous heating plate 7, and weld the titanium alloy lock bottom structure at a set pulse frequency of 250 Hz. During welding, under the action of the pulsed TIG arc, the fluidity of the molten pool changes, and because of the action of the synchronous heat field of the synchronous heating plate 7, the fluidity of the molten pool is prolonged, which promotes the escape of pores and completes the welding; S108, after the welding is completed, the temperature controller 8 is maintained within the set temperature for 10 seconds, and then the temperature controller 8 is turned off to allow the synchronous heating plate 7 to naturally cool to room temperature; S109, turn off the laser 1, TIG welding power supply 5, and argon gas bottle 6, and remove the welding sample; after the synchronous heating plate 7 cools to room temperature, turn off the power supply and end the welding.

[0032] In addition, in order to verify the effect of the temperature of the synchronous heating plate 7 and the set pulse frequency set in this application, the distribution of pores during welding under the conditions of pulse frequency of 0Hz, 100Hz, and 500Hz, and the synchronous thermal field temperature of 300K, 350K, 400K, and 500K were verified respectively. The welding method is consistent with the method of the above-mentioned embodiment 2, which will not be repeated here. By using different frequencies and different temperatures of the synchronous heating plate 7, the following results are obtained: Figure 4 and Figure 5 The X-ray flaw detection results of the titanium alloy lock bottom structure under different pulse frequencies and different synchronous heating plate 7 temperatures are shown in the figure. It can be seen from the figure that: 1. When there is no pulse frequency (such as Figure 4 (a) shows that chain-like tiny pores appear; when the pulse frequency is 100 Hz (as shown in Figure 4 (b) shows that a large number of unevenly distributed fine pores appear in the weld. As the pulse frequency increases, when the pulse frequency is 250Hz (as shown in Figure 4 (c) shows that the number of pores is the least, but there are still small pores; when the pulse frequency is 500Hz (as shown in Figure 4 (d) shows that the number of pores increases. Therefore, the number of pores is the smallest when the pulse frequency is 250 Hz. 2. When the synchronous thermal field temperature is 300K (such as Figure 5 (a) shows that the lock bottom structure has a serious tendency to pores, and a large number of small pores appear; when the temperature rises to 350K (as shown in Figure 5 (b)), the number of pores decreases; when the temperature rises to 400K (as shown in Figure 5 (c)), the number of pores further decreases; when the temperature rises to 500K (as shown in Figure 5 (d) shows that the number of pores in the weld is significantly reduced compared to that at 400K. When the synchronous thermal field temperature is 600K (as shown in Figure 5 (e) shows that the porosity defects in the welded joint disappear.

[0033] In summary, by adjusting the pulse frequency, the pores are controlled, and a weld with fewer pores is obtained at a frequency of 250Hz; and as the temperature of the synchronous thermal field increases, the pores in the welded joint of the titanium alloy lock bottom structure decrease. When the synchronous thermal field temperature is 600K, the pore defects of the titanium alloy joint are effectively eliminated. Therefore, at this frequency, the pores of the titanium alloy lock bottom structure are eliminated by applying a synchronous thermal field.

[0034] Example 3: Figure 6 As shown in the figure, in order to test the mechanical properties of the welded joint, the tensile test of the titanium alloy lock bottom structure under the synchronous thermal field temperature was compared. The results show that with the increase of the synchronous thermal field temperature, the ultimate tensile strength of the titanium alloy lock bottom structure is significantly improved; when the synchronous thermal field temperature is 300K, the ultimate tensile strength is 254.2MPa; with the increase of the synchronous thermal field temperature, the ultimate tensile strength is 326.7Mpa when the synchronous thermal field temperature is 350K; when the synchronous thermal field temperature is 400K, the strength reaches 427.4Mpa; at 500K, the ultimate tensile strength is increased to 538.8Mpa, and when the temperature reaches the highest (600K), the ultimate tensile strength reaches 633.8Mpa. Pulsed TIG laser hybrid welding assisted by synchronous thermal field can effectively eliminate welding pores and improve the mechanical properties of titanium alloy lock bottom structure.

[0035] Example 4: Figure 1 , 2 As shown, an embodiment of the present invention discloses a device for eliminating welding pores of a titanium alloy lock bottom structure, comprising a laser device, a TIG welding device, a synchronous thermal field device and a titanium alloy lock bottom structure substrate 9, wherein the laser device comprises a laser 1, a laser welding head 2 and a host computer 3, and the host computer 3, the laser 1 and the laser welding head 2 are connected in sequence; the TIG welding device comprises a TIG welding gun 4, a TIG welding power source 5 and an argon gas bottle 6, and the argon gas bottle 6, the TIG welding power source 5 and the TIG welding gun 4 are connected in sequence; the synchronous thermal field device comprises a synchronous heating plate 7 and a temperature controller 8, and the temperature controller 8 is connected to the synchronous heating plate 7; the titanium alloy lock bottom structure substrate 9 is fixed on the synchronous heating plate 7, and the titanium alloy lock bottom structure substrate 9 comprises a pad 10 and two docking plates 11, and the pad 10 is arranged between the two docking plates 11.

[0036] According to the needs, the angle between the TIG welding gun 4 and the titanium alloy lock bottom structural member substrate 9 (Ti6Al4V, referred to as TC4) is 40°; the distance between the tungsten tip of the TIG welding gun 4 and the center of the laser beam spot emitted by the laser welding head 2 is 6 mm; the distance between the tungsten tip of the TIG welding gun 4 and the titanium alloy lock bottom structural member substrate 9 is 5 mm. In addition, in order to prevent the reflection of the titanium alloy, the laser pilot method is used for welding, that is, the laser is in front and the arc is in the back, and the left welding method is used for welding.

[0037] The distance between the tungsten tip of the TIG welding gun 4 and the titanium alloy lock bottom structure substrate 9 is set to 5 mm in order to avoid excessive arc pressure.

[0038] Among them, the titanium alloy lock bottom structure consists of two docking plates 11 and a pad 10, wherein the docking plate 11 has a specification of 100mm×50mm×3mm, and the pad 10 has a specification of 120mm×9mm×2mm.

[0039] Example 5: The embodiment of the present invention discloses a titanium alloy lock bottom structural component welding product, which is prepared by a method for eliminating welding pores of a titanium alloy lock bottom structural component.

Claims

1. A method for eliminating welding pores of titanium alloy lock bottom structural parts, characterized in that: include: Set the temperature of the synchronous heating plate to 600K, and set the pulse TIG welding pulse frequency to 250Hz. After the parameters are set, the titanium alloy lock bottom structure is heated by the synchronous heating plate so that the temperature of the titanium alloy lock bottom structure is consistent with the heating temperature set by the synchronous heating plate to form a synchronous heat field, and the titanium alloy lock bottom structure is welded using the set pulse frequency. During the welding process, the titanium alloy lock bottom structure is heated in real time using the synchronous heat field to eliminate the welding pores of the titanium alloy lock bottom structure.

2. The method for eliminating welding pores of titanium alloy lock bottom structural parts according to claim 1, characterized in that: Setting the pulse frequency of pulse TIG welding includes the following steps: The titanium alloy lock bottom structure is welded using different pulse frequencies; X-ray flaw detection was performed on titanium alloy lock bottom structural parts after welding at different pulse frequencies to detect the porosity after welding; The pulse frequency corresponding to the titanium alloy lock bottom structure with the least pore defects is determined as the set pulse frequency.

3. The method for eliminating welding pores of titanium alloy lock bottom structural parts according to claim 1, characterized in that: The method also includes treating the titanium alloy lock bottom structure before heating, wherein the treatment process includes: The titanium alloy lock bottom structure is polished and fixed; wherein the titanium alloy lock bottom structure comprises a docking plate and a pad, the docking plate is placed on the pad and tightened with a clamp.

4. The method for eliminating welding pores of titanium alloy lock bottom structural parts according to claim 1, characterized in that: It also includes pore elimination, wherein the elimination process includes: The force of the pores in the molten pool is shown in the following formula: ， in, F h For the joint efforts, F h When >0, the pores escape to the surface of the molten pool. F h When <0, stomatal escape is inhibited; F for buoyancy; F t The thrust generated by the molten pool flow; F g is gravity; F d It is the viscosity of liquid metal.

5. A device for eliminating welding pores of titanium alloy lock bottom structural parts, characterized in that: It includes a laser device, a TIG welding device, a synchronous thermal field device and a titanium alloy lock bottom structural component substrate. The laser device includes a laser, a laser welding head and a host computer, which are connected in sequence; the TIG welding device includes a TIG welding gun, a TIG welding power supply and an argon gas cylinder, which are connected in sequence; the synchronous thermal field device includes a synchronous heating plate and a temperature controller, which is connected to the synchronous heating plate; the titanium alloy lock bottom structural component substrate is fixed on the synchronous heating plate, and the titanium alloy lock bottom structural component substrate includes a pad and two docking plates, and the pad is arranged between the two docking plates.

6. The device for eliminating welding pores of titanium alloy lock bottom structural parts according to claim 5, characterized in that: The angle between the TIG welding gun and the titanium alloy lock bottom structural component substrate is 40°; the distance between the tungsten tip of the TIG welding gun and the center of the laser beam spot emitted by the laser welding head is 6 mm; the distance between the tungsten tip of the TIG welding gun and the titanium alloy lock bottom structural component substrate is 5 mm.

7. A titanium alloy lock bottom structural component welding product, characterized in that: The product is prepared by the method for eliminating welding pores of titanium alloy lock bottom structural parts as described in any one of claims 1 to 4.

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