Repair welding repair method for casting defects of isometric crystal high-temperature alloy structural part

Abstract

The invention relates to a repair welding repair method for casting defects of an equiaxed crystal high-temperature alloy structural part, belongs to the technical field of welding repair, and solves the problems that in the prior art, the repair welding success rate of the casting defects of the equiaxed crystal high-temperature alloy structural part is low, the repair welding result stability is poor, and the repair welding accessibility of local narrow parts is poor. The invention discloses a repair welding repair method for casting defects of an isometric crystal high-temperature alloy structural part. The repair welding repair method comprises the following steps that S1, defects are removed in a mechanical mode, and grooves are machined; s2, cleaning before welding; s3, the structural part is placed in a vacuum argon-filled welding box; s4, arc striking welding, wherein the welding process passes are arranged as follows: (1) after arc striking, 2-4 seconds are used firstly to enable the base metal to form a molten pool; (2) adding wires into the molten pool, and slowly feeding the wires; 3, welding spots are fully stacked through fractional wire feeding, and annular arc conveying is carried out; (4) the electric arc is slowly conveyed for a circle along the weld toe; (5) ending; and S5, performing fluorescence and X-ray detection after cooling. The casting defects of the isometric crystal high-temperature alloy structural part are efficiently and stably repaired.

Description

Technical Field

[0001] The invention relates to the technical field of welding repair, and in particular to a welding repair method for casting defects of an equiaxed crystal high-temperature alloy structural part. Background Art

[0002] Equiaxed crystal high temperature alloys are mainly used for the structural parts of aircraft engines, and their quality requirements are very high. In view of the complexity of the casting structure and the volatility of the casting process, equiaxed crystal high temperature alloy structural parts such as guides and casings are prone to cold shut, looseness, pores, cracks and other casting defects during the manufacturing process, which significantly affects the delivery quality and cycle of the task. Therefore, repair welding of casting defects is an important guarantee measure for casting delivery, and the construction of casting repair welding capabilities has become one of the important tasks of various units in the industry.

[0003] At present, most of the industry uses manual argon arc welding in atmospheric environment to repair structural parts, which has problems such as easy oxidation of welding spots and inaccessible repair welding in local narrow parts. The surface quality of the repair welding area is poor. At the same time, the probability of cracks and deformation caused by repair welding increases, affecting the dimensional accuracy, life and reliability of castings. A small number of repair welding boxes are used for repair welding, but because equiaxed high-temperature alloys are hard and difficult to melt, the success rate of repair welding is low, and the repair welding process often relies on the experience of welders, resulting in poor batch stability. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a method for repairing casting defects of equiaxed crystal high-temperature alloy structural parts by repair welding, so as to solve at least one of the problems of low success rate of repair welding of casting defects of existing equiaxed crystal high-temperature alloy structural parts, poor stability of repair welding results, poor accessibility of repair welding in local narrow areas, poor surface quality of repair welding area, and easy oxidation of welds.

[0005] The embodiment of the present invention provides a method for repairing casting defects of an equiaxed high-temperature alloy structural part by welding, comprising the following steps:

[0006] S1. Mechanical method to eliminate defects and groove processing;

[0007] S2, cleaning before welding;

[0008] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0009] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0010] ①: After arc is struck, it takes 2-4 seconds to form a molten pool in the base material;

[0011] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0012] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld points and make them 1 to 3 mm higher than the base material;

[0013] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0014] ⑤: Ending, the arc stays for 1-3 seconds or moves in a circular motion for several times, then slowly closes the arc, and within 2 seconds after closing the arc, the arc is struck and extinguished again, and repeated 1-4 times;

[0015] S5. After cooling, perform fluorescence and X-ray detection.

[0016] Specifically, the mechanical method in step S1 includes grinding and polishing, mechanical cutting, milling, grinding, and drilling. After the mechanical treatment, the metallic luster is exposed around the defect, and the edge is free of burrs and flash.

[0017] Furthermore, after the defects are eliminated mechanically, U-shaped or V-shaped groove processing is performed on the defective parts.

[0018] Preferably, the pre-welding cleaning in step S2 includes pickling or alkali cleaning, and the cleaned structural parts are blown dry with an air gun or dried in an oven.

[0019] It should be noted that the pre-welding treatment in step S3 includes: repeatedly wiping the welding wire with acetone or alcohol until there is no visible contaminant on the surface and it has a consistent metallic luster; grinding the end of the tungsten pole into a flat-bottomed cone with a tungsten pole length of 3cm-20cm.

[0020] Furthermore, in step S4, the vacuum argon-filled welding box is first evacuated to <8Pa, and then filled with argon to -0.01MPa~+0.05MPa, arc welding is initiated and certain welding process parameters are controlled.

[0021] Exemplarily, the certain welding process parameters in step S4 include: when the thickness of the base material is less than 2 mm, the tungsten electrode diameter is 1.6 to 4.0 mm, the welding wire diameter is 0.5 to 4.0 mm, the welding current is 30 to 60 A, and the welding time is 3 to 40 s.

[0022] The certain welding process parameters in step S4 also include: when the thickness of the base material is 2 to 10 mm, the diameter of the tungsten electrode is 1.6 to 4.0 mm, the diameter of the welding wire is 0.5 to 4.0 mm, the welding current is 30 to 90 A, and the welding time is 3 to 60 s.

[0023] The certain welding process parameters described in step S4 also include: when the base material thickness is greater than 10 mm, the tungsten electrode diameter is greater than 1.6 mm, the welding wire diameter is greater than 0.5 mm, the welding current is greater than 40 A, and the welding time is greater than 10 s.

[0024] It is worth noting that during the third pass of the welding process in step S4, the arc height is controlled to be 2 to 3 mm.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] 1. The present invention optimizes and reasonably designs the repair welding process and corresponding welding process parameters, performs the argon tungsten arc welding process in a 5-pass sequence, and selects appropriate welding process parameters to achieve a one-time repair welding success rate of >90%, which is much higher than the 40% qualified rate of manual argon arc welding under the existing atmospheric environment; especially for complex structural parts made of equiaxed high-temperature alloys with high Al and Ti contents, the 5-pass welding process can effectively overcome the thermal crack sensitivity of the structural parts caused by the high Al and Ti contents and the repair welding difficulties and unstable repair welding quality caused by the narrow position of the welding points, and the one-time repair welding success rate is maintained at more than 90%, which greatly improves the production efficiency.

[0027] 2. The present invention performs repair welding of complex components in a vacuum argon-filled welding box equipped with a position shifting system. On the one hand, it effectively isolates the surrounding air, protects the welding area from oxidation, better controls the arc and the molten pool, and reduces welding defects. On the other hand, the position shifting system that can move in multiple degrees of freedom directions can flexibly adjust the orientation of the structural parts according to the position of the welding point, thereby solving the problems of poor accessibility in narrow parts of complex components and the inability to accurately adjust the welding gun angle and the workpiece position, while making the direction of the repair welding as vertically downward as possible, thereby ensuring the welding quality.

[0028] 3. The present invention reasonably matches welding process parameters such as welding current and welding time according to the thickness of the base material, the depth and size of the repair welding defects, further ensuring a high welding success rate and stability.

[0029] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0031] Figure 1 The test results of Example 1 of the present invention are as follows;

[0032] Figure 2 The test results of comparative example 1 of the present invention are as follows;

[0033] Figure 3 The test results of comparative example 2 of the present invention are as follows;

[0034] Figure 4 The test results of comparative example 3 of the present invention are as follows;

[0035] Figure 5 The test results of comparative example 4 of the present invention are as follows;

[0036] Figure 6 It is a schematic diagram of the main view of the vacuum argon-filled welding box body and the displacement system of the present invention;

[0037] Figure 7 It is a left schematic diagram of the vacuum argon-filled welding box body and the displacement system of the present invention.

[0038] Reference numerals:

[0039] 1-Box body; 2-Box door; 3-Observation window; 4-Operation gloves; 5-Welding handle connecting device; 6-Air release valve; 7-Bracket; 8-Pallet; 9-Workbench. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0041] On the one hand, equiaxed crystal high-temperature alloys have high Al and Ti contents, among which the "Al+Ti" content is greater than 4wt%. When conventional repair welding processes are used for repair joints, thermal cracks are very likely to occur, and repeated repairs are often required for more than two times, resulting in extremely unstable repair quality. The qualified rate of repair of high-temperature alloy structural parts with high Al and Ti contents is usually less than 50%. On the other hand, equiaxed crystal high-temperature alloys are mainly used for aircraft engine components with complex structures. When repairing defects of complex structural parts, the welding spots are relatively narrow or the position is relatively small, resulting in poor repair welding accessibility, difficult to control the welding gun angle, low repair welding success rate, and are not suitable for repair methods such as laser cladding and laser welding.

[0042] A specific embodiment of the present invention discloses a method for repairing casting defects of an equiaxed high-temperature alloy structural part by welding, comprising the following steps:

[0043] S1. Mechanical method to eliminate defects and groove processing;

[0044] S2, cleaning before welding;

[0045] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0046] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0047] ①: After striking the arc, it takes 2 to 4 seconds to form a molten pool in the base material;

[0048] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0049] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld spot to 1-3mm above the base material, control the arc height to 2-3mm, and make a circular swing in the weld spot to ensure that the welding wire and the base material are fully fused;

[0050] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0051] ⑤: Ending, the arc stays for 1-3 seconds or moves in a circular motion for several times, then slowly closes the arc, and within 2 seconds after closing the arc, the arc is struck and extinguished again, and repeated 1-4 times;

[0052] S5. After cooling, perform fluorescence and X-ray detection.

[0053] Preferably, the mechanical method in step S1 includes grinding and polishing, mechanical cutting, milling, grinding, and drilling; after mechanical treatment, the defect is surrounded by a metallic luster, and the edge is free of burrs and flash;

[0054] After the structural parts are mechanically eliminated of defects, U-shaped or V-shaped grooves are processed at the defects.

[0055] Furthermore, the pre-weld cleaning includes pickling or alkaline cleaning, and the cleaned casting is blown dry with an air gun or dried in an oven; the pickling solution includes one or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chromic acid, and hydrofluoric acid to remove oxide film, impurities and rust on the metal surface; the alkaline cleaning solution is sodium hydroxide or sodium carbonate solution to remove grease on the metal surface.

[0056] Preferably, for castings with smaller areas and fewer defects, pickling or alkali cleaning is not required before repair welding. The area to be welded can be wiped with acetone to remove grinding chips, oil stains and dust.

[0057] Furthermore, if Figure 6 , Figure 7 As shown, the vacuum argon-filled welding box in step S3 includes a box body 1, a welding machine system, a displacement system, a vacuum system, a control system, a cooling system, a detection system, and an argon-filled system;

[0058] The box body comprises a box door 2, operating gloves 4 and an observation window 3 are arranged on both sides of the box body, and a welding torch connecting device 5 and an air release valve 6 are arranged on the top of the box body;

[0059] The welding machine system comprises a welding machine body, a welding handle, a welding gun and a wire feeder, wherein the welding machine body is located outside the box, and the welding machine body is a DC tungsten inert gas arc welding machine or an AC / DC tungsten inert gas arc welding machine; the output end of the welding machine body is connected to the welding gun and the wire feeder inside the box through the welding handle, the welding gun is equipped with a tungsten electrode, and the welding wire is fed into the welding area through the wire feeder; when in use, the operator controls the welding gun by operating the welding handle through the operating gloves, and starts the welding arc at the same time to perform welding operations;

[0060] The displacement system includes a bracket 7 installed at the bottom of the box, a support plate 8 located above the bracket and movable along the axial direction of the box, and a workbench 9 installed on the support plate; the workbench can move in multiple degrees of freedom, such as front and back, left and right, up and down, rotation, and yaw.

[0061] When the vacuum argon-filled welding box is used, the pallet is moved to move the workbench to the box door, the structural parts that have been processed before welding are accurately placed on the workbench of the displacement system outside the box and clamped, the pallet is moved again to send the workbench with the structural parts into the box, and the direction of the workbench is adjusted according to the position of the welding point, so that the welding point is located at a position that is easy to weld; the box door is closed and the vacuum system is used to evacuate the vacuum to <8Pa; and the argon filling system is used to fill the argon to -0.01MPa~+0.05MPa;

[0062] In the vacuum welding box, extend the tungsten electrode clamped on the welding gun above the welding point of the structural part, strike the arc, add welding wire, and perform repair welding;

[0063] After the repair welding is completed, the workbench is leveled to return the structural parts to the middle position, and the vacuum process is performed again to exhaust the argon gas in the box. The box air release valve is opened to restore the box pressure to atmospheric state, the box door is opened, and the structural parts are moved out of the box through the pallet.

[0064] It is worth noting that when adjusting the position of the structural member in step S3, for the welding points that require vertical welding and horizontal welding, the structural member should be placed on its side before welding, and the direction of the repair welding should be vertically downward as much as possible.

[0065] It should be noted that the pre-welding treatment of the welding wire in step S3 includes: repeatedly wiping the welding wire with acetone or alcohol until there is no visible contaminant on the surface and the surface has a consistent metallic luster;

[0066] In a possible design, the welding wire is made of the same material as the parent material.

[0067] The pre-welding treatment of the tungsten electrode includes: grinding the end of the tungsten electrode into a flat-bottomed cone, the length of the tungsten electrode is 3cm-20cm, and the tungsten electrode is clamped to the welding gun without looseness.

[0068] Repair welding of complex components is carried out in a vacuum argon-filled welding box equipped with a position shifting system: on the one hand, it effectively isolates the surrounding air, protects the welding area from oxidation, better controls the arc and molten pool, and effectively reduces welding defects; on the other hand, the position shifting system that can move in multiple degrees of freedom directions can flexibly adjust the orientation of the structural parts according to the position of the weld, solving the problems of poor accessibility to complex components and narrow parts and difficulty in adjusting the welding gun angle, while making the direction of the repair welding as vertically downward as possible, thus ensuring the welding quality.

[0069] Preferably, the certain welding process parameters in step S4 include: when the thickness of the parent material is less than 2 mm, the tungsten electrode diameter is 1.6-4.0 mm, the welding wire diameter is 0.5-4.0 mm, the welding current is 30-60 A, and the total welding time of ① to ⑤ passes in step S4 is 3-40 s; when the thickness of the parent material is 2-10 mm, the tungsten electrode diameter is 1.6-4.0 mm, the welding wire diameter is 0.5-4.0 mm, the welding current is 30-90 A, and the total welding time of ① to ⑤ passes in step S4 is 3-60 s; when the thickness of the parent material is greater than 10 mm, the tungsten electrode diameter is greater than 1.6 mm, the welding wire diameter is greater than 0.5 mm, the welding current is greater than 40 A, and the total welding time of ① to ⑤ passes in step S4 is greater than 10 s.

[0070] The welding time is determined according to the depth and size of the repair welding defect;

[0071] In one possible design, for a defect with a depth of 1 mm and a diameter of 1.5 mm on a base material with a thickness of 1.8 mm, a tungsten electrode diameter of 1.6 mm and a welding wire diameter of 1 mm are selected, with a welding current of 40 A and a welding time of 40 s, or a welding current of 70 A and a total welding time of 20 s for passes ① to ⑤ in step S4.

[0072] In one possible design, for a defect with a depth of 10 mm and a diameter of 20 mm on a base material with a thickness of 20 mm, a tungsten electrode diameter of 2.4 mm and a welding wire diameter of 1.5 mm are selected, the welding current is 50 A, and the welding time is 120 s, or the welding current is 80 A, and the total welding time for passes ① to ⑤ in step S4 is about 60 s.

[0073] Furthermore, in step S4, a five-pass welding process is sequentially adopted; during the third pass, the arc height is controlled at 2 to 3 mm, and a circular oscillation is performed in the weld spot to ensure that the welding wire and the base material are fully fused; in the fourth pass, the arc is slowly moved along the weld toe at a speed of 1 to 2 mm / s to prevent the weld spot and the base material from not being fully fused.

[0074] By performing the argon tungsten electrode welding process in the described five-pass sequence and selecting appropriate welding process parameters, the success rate of one-time repair welding is greater than 90%, which is much higher than the 30% qualified rate of existing vacuum repair welding. In particular, for complex structural parts made of equiaxed high-temperature alloys with high Al and Ti contents, the five-pass welding process can effectively overcome the thermal crack sensitivity of the structural parts caused by the high Al and Ti contents, the difficulty of repair welding caused by the narrow position of the welding spot, and the unstable quality of repair welding. The success rate of one-time repair welding is maintained above 90%, which greatly improves the production efficiency.

[0075] In summary, the present invention optimizes and reasonably designs the repair welding process and the corresponding welding process parameters, performs the tungsten electrode argon shielded welding process in a 5-pass sequence, and selects appropriate welding process parameters to achieve a one-time repair welding success rate of >90%; effectively overcomes the thermal crack sensitivity of structural parts caused by high Al and Ti contents and the difficulty and unstable repair welding quality caused by the narrow position of the welding spot, thereby greatly improving the production efficiency; by repair welding complex components in a vacuum argon-filled welding box equipped with a displacement system, the welding area is protected from oxidation and welding defects are reduced; the orientation of the structural parts is flexibly adjusted according to the position of the welding spot, so as to solve the problems of poor accessibility of narrow parts of complex components and the inability to accurately adjust the welding gun angle and the workpiece position, thereby improving the welding quality.

[0076] The following describes the welding repair method for casting defects of equiaxed high-temperature alloy structural parts according to the present invention in conjunction with specific embodiments.

[0077] Example 1

[0078] This embodiment provides a method for repairing casting defects of a K4169 structural component by welding.

[0079] The thickness of the base material is 4mm, the defect depth on the base material is 1mm and the diameter is 1.5mm. The welding wire material is HGH4169.

[0080] The welding process adopted is: welding wire diameter 0.8mm, welding current 40A, and total welding time 25s after arc initiation.

[0081] The specific repair steps are:

[0082] S1. Mechanical method to eliminate defects and groove processing;

[0083] S2, cleaning before welding;

[0084] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0085] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0086] ①: After striking the arc, it takes 2 to 4 seconds to form a molten pool in the base material;

[0087] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0088] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld spot to 2mm above the base metal. Control the arc height by 2-3mm and make circular swings in the weld spot to ensure that the welding wire and base metal are fully fused.

[0089] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0090] ⑤: Ending, the arc stays for 1-3 seconds, then slowly closes, briefly arcs and then extinguishes, repeating twice;

[0091] S5. After cooling, perform fluorescence and X-ray detection.

[0092] The welding wire and the base material are well fused, and no cracks, looseness or other defects are found inside. The fluorescence and X-ray test results show no defects, such as Figure 1 shown.

[0093] Example 2

[0094] This embodiment provides a method for repairing the casting defects of K423A structural parts by welding. The specific repair steps are the same as those in embodiment 1, except that:

[0095] The thickness of the base material is 2mm, the defect depth on the base material is 0.5mm and the diameter is 2mm. The welding wire material is HGH3113.

[0096] The welding process adopted is: welding wire diameter 1mm, welding current 40A, and total welding time 20s after arc initiation.

[0097] The welding wire and the base material are well fused, and no cracks, looseness or other defects are found inside. The fluorescence and X-ray test results show no defects. Figure 1 resemblance.

[0098] Example 3

[0099] This embodiment provides a method for repairing casting defects of a K4169 structural component by welding.

[0100] The thickness of the base material is 1.8mm, the depth of the defect on the base material is 0.8mm, the diameter is 1.5mm, and the welding wire material is HGH4169.

[0101] The welding process adopted is: welding wire diameter 0.8mm, welding current 70A, and total welding time 20s after arc initiation.

[0102] The specific repair steps are:

[0103] S1. Mechanical method to eliminate defects and groove processing;

[0104] S2, cleaning before welding;

[0105] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0106] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0107] ①: After striking the arc, it takes 2 to 4 seconds to form a molten pool in the base material;

[0108] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0109] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld spot to 2mm above the base metal. Control the arc height by 2-3mm and make circular swings in the weld spot to ensure that the welding wire and base metal are fully fused.

[0110] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0111] ⑤: Ending, the arc stays for 1-3 seconds, then slowly closes, briefly arcs and then extinguishes, repeating twice;

[0112] S5. After cooling, perform fluorescence and X-ray detection.

[0113] The welding wire and the base material are well fused, and no cracks, looseness or other defects are found inside. The fluorescence and X-ray test results show no defects. Figure 1 resemblance.

[0114] Example 4

[0115] This embodiment provides a method for repairing casting defects of a K4169 structural component by welding.

[0116] The thickness of the base material is 20mm, the defect depth on the base material is 10mm and the diameter is 20mm. The welding wire material is HGH4169.

[0117] The welding process adopted is: welding wire diameter 1.5mm, welding current 80A, and total welding time 60s after arc initiation.

[0118] The specific repair steps are:

[0119] S1. Mechanical method to eliminate defects and groove processing;

[0120] S2, cleaning before welding;

[0121] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0122] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0123] ①: After striking the arc, it takes 2 to 4 seconds to form a molten pool in the base material;

[0124] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0125] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld spot to 2mm above the base metal. Control the arc height by 2-3mm and make circular swings in the weld spot to ensure that the welding wire and base metal are fully fused.

[0126] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0127] ⑤: Ending, the arc stays for 1-3 seconds, then slowly closes, briefly arcs and then extinguishes, repeating 4 times;

[0128] S5. After cooling, perform fluorescence and X-ray detection.

[0129] The welding wire and the base material are well fused, and no cracks, looseness or other defects are found inside. The fluorescence and X-ray test results show no defects. Figure 1 resemblance.

[0130] Comparative Example 1

[0131] This embodiment provides a method for repairing casting defects of a K4169 structural component by welding.

[0132] The thickness of the base material is 4mm, the defect depth on the base material is 1mm and the diameter is 1.5mm. The welding wire material is HGH4169.

[0133] The welding process adopted is: welding wire diameter 0.8mm, welding current 40A, and total welding time 25s after arc initiation.

[0134] The specific repair steps are the same as those in Example 1, except that the fifth process is not performed in step S4.

[0135] After testing, there is an obvious arc pit in the middle of the weld, and the fluorescence test results after grinding are defective, such as Figure 2 shown.

[0136] Comparative Example 2

[0137] This embodiment provides a method for repairing casting defects of a K4169 structural component by welding.

[0138] The thickness of the base material is 4mm, the defect depth on the base material is 1mm and the diameter is 1.5mm. The welding wire material is HGH4169.

[0139] The welding process adopted is: welding wire diameter 0.8mm, welding current 40A, welding time 25s.

[0140] The specific repair steps are the same as those in Example 1, except that the fourth process is not performed in step S4.

[0141] Feeding the wire too fast, the welding wire and the base material are not fused, and there is an obvious cavity inside, such as Figure 3 shown.

[0142] Comparative Example 3

[0143] This embodiment provides a method for repairing casting defects of a K423A structural component by welding.

[0144] The thickness of the base material is 2mm, the defect depth on the base material is 0.5mm and the diameter is 2mm. The welding wire material is HGH3113.

[0145] The welding process adopted is: welding wire diameter 1mm, welding current 40A, and total welding time 20s after arc initiation.

[0146] The specific repair steps are:

[0147] S1. Mechanical method to eliminate defects and groove processing;

[0148] S2, cleaning before welding;

[0149] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0150] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0151] ①: After striking the arc, it takes 2 to 4 seconds to form a molten pool in the base material;

[0152] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0153] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld points until they are 2mm above the base material, and the arc position is fixed on one side;

[0154] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0155] ⑤: Ending, the arc stays for 1-3 seconds, then slowly closes, arc starts and extinguishes within 2 seconds after arc closing, repeat twice;

[0156] S5. After cooling, perform fluorescence and X-ray detection.

[0157] Because the arc position is fixed on one side in the third process of step S4, the heat affected zone of the base material on one side is large, overheating and shrinkage occur, and undercut is formed. Figure 4 shown.

[0158] Comparative Example 4

[0159] This embodiment provides a method for repairing casting defects of a K423A structural component by welding.

[0160] The thickness of the base material is 2mm, the defect depth on the base material is 0.5mm and the diameter is 2mm. The welding wire material is HGH3113.

[0161] The welding process adopted is: welding wire diameter 1mm, welding current 65A, and total welding time 70s after arc initiation.

[0162] The specific repair steps are:

[0163] S1. Mechanical method to eliminate defects and groove processing;

[0164] S2, cleaning before welding;

[0165] S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode;

[0166] S4. The vacuum welding box is first evacuated, and then filled with argon gas to a certain pressure. Arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows:

[0167] ①: After striking the arc, it takes 2 to 4 seconds to form a molten pool in the base material;

[0168] ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s;

[0169] ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld spot to 2mm above the base metal. Control the arc height by 2-3mm and make circular swings in the weld spot to ensure that the welding wire and base metal are fully fused.

[0170] ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe;

[0171] ⑤: Ending, the arc stays for 1-3 seconds, then slowly closes, arc starts and extinguishes within 2 seconds after arc closing, repeat twice;

[0172] S5. After cooling, perform fluorescence and X-ray detection.

[0173] Results show that the back of the solder joint is melted through, and the fluorescence test results show defects, such as Figure 5 shown.

[0174] It can be seen from Example 1 and Comparative Examples 1 to 3 that the five welding processes in the welding process are indispensable. If one of the processes is skipped or not operated as required, defects will be formed and the repair welding will fail. It can be seen from Example 2 and Comparative Example 4 that Comparative Example 4 adopts the welding process of the present invention, but the welding process parameters are improperly selected, which will still lead to repair welding failure. Therefore, when using a vacuum welding box to repair complex components, not using the repair welding process and welding process parameters provided by the present invention will result in a low repair welding success rate.

[0175] If the traditional manual argon arc welding repair method is used in an atmospheric environment, the welding point is small, the welding gun angle cannot be determined, and it is even impossible to approach the welding point, making it impossible to complete the repair welding of complex structural parts.

[0176] In summary, the present invention optimizes and reasonably designs the repair welding process and the corresponding welding process parameters, performs the argon tungsten electrode welding process in a 5-pass sequence, and selects appropriate welding process parameters to achieve a one-time repair welding success rate of >90%; effectively overcomes the thermal crack sensitivity of the structural parts caused by high Al and Ti contents and the difficulty of repair welding and unstable repair welding quality caused by the narrow position of the welding point, thereby greatly improving the production efficiency.

[0177] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for repairing casting defects of equiaxed high-temperature alloy structural parts by welding, characterized in that: The steps include: S1. Mechanical method to eliminate defects and groove processing; S2, cleaning before welding; S3, placing the structural part to be repaired in a vacuum argon-filled welding box, adjusting the position of the structural part, and performing pre-welding treatment on the welding wire and tungsten electrode; S4. The vacuum argon-filled welding box is first evacuated, and then filled with argon to a certain pressure, arc welding is started and certain welding process parameters are controlled. The welding process is arranged as follows: ① After striking the arc, it takes 2-4 seconds to form a molten pool in the base material; ②: Add wire to the molten pool and feed the wire slowly at a speed of 1-5 mm / s; ③ Pass: Feed the wire several times and move the arc in a circular motion to fill the weld points and make them 1 to 3 mm higher than the base material; ④: Use a speed of 1-2 mm / s to slowly move the arc along the weld toe; ⑤: Ending, the arc stays for 1-3 seconds or moves in a circular motion for several times, then slowly closes the arc, and within 2 seconds after closing the arc, the arc is struck and extinguished again, and repeated 1-4 times; S5. After cooling, perform fluorescence and X-ray detection.

2. The repair method according to claim 1, characterized in that: The mechanical method in step S1 includes grinding and polishing, mechanical cutting, milling, grinding, and drilling. After mechanical processing, the metallic luster is exposed around the defect, and the edge is free of burrs and flash.

3. The repair method according to claim 2, characterized in that: After the defects are eliminated mechanically, U-shaped or V-shaped grooves are processed at the defects.

4. The repair method according to claim 1, characterized in that: The pre-welding cleaning in step S2 includes pickling or alkali cleaning, and the cleaned structural parts are blown dry with an air gun or dried in an oven.

5. The repair method according to claim 1, characterized in that: The pre-welding treatment in step S3 includes: repeatedly wiping the welding wire with acetone or alcohol until the surface is free of visible contaminants and has a consistent metallic luster; grinding the tungsten pole tip into a flat-bottomed cone with a tungsten pole length of 3 cm-20 cm.

6. The repair method according to claim 1, characterized in that: In step S4, the vacuum argon-filled welding box is first evacuated to a vacuum level of <8 Pa, and then filled with argon to a level of -0.01 MPa to +0.05 MPa, arc welding is initiated, and certain welding process parameters are controlled.

7. The repair method according to claim 6, characterized in that: The certain welding process parameters in step S4 include: when the thickness of the base material is less than 2 mm, the tungsten electrode diameter is 1.6-4.0 mm, the welding wire diameter is 0.5-4.0 mm, the welding current is 30-60 A, and the welding time is 3-40 s.

8. The repair method according to claim 6, characterized in that: The certain welding process parameters in step S4 also include: when the thickness of the base material is 2 to 10 mm, the diameter of the tungsten electrode is 1.6 to 4.0 mm, the diameter of the welding wire is 0.5 to 4.0 mm, the welding current is 30 to 90 A, and the welding time is 3 to 60 s.

9. The repair method according to claim 6, characterized in that: The certain welding process parameters described in step S4 also include: when the base material thickness is greater than 10 mm, the tungsten electrode diameter is greater than 1.6 mm, the welding wire diameter is greater than 0.5 mm, the welding current is greater than 40 A, and the welding time is greater than 10 s.

10. The repair method according to claim 6, characterized in that: During the third pass of the welding process in step S4, the arc height is controlled to be 2 to 3 mm.

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