A method of additive manufacturing of a high temperature alloy product void repair

Abstract

The application relates to a kind of additive manufacturing high-temperature alloy product lack amount repair methods, belong to the field of additive manufacturing product repair, solve the problem that high-temperature alloy high-precision thin-walled area is difficult to repair in prior art.A kind of additive manufacturing high-temperature alloy product lack amount repair method, comprising the following steps: S1, three-dimensional scanning and comparison are carried out to additive manufacturing product, and the product lack amount area and thickness characteristics are confirmed;S2, the lack amount area is mechanically polished and cleaned;S3, the handheld laser equipment and welding wire are used to fill the lack amount area and repair the lack amount;S4, the repair position is detected by X-ray;S5, the product after repair welding is heat treated;S6, the excess height of repair welding is mechanically processed;S7, the repair position is detected by fluorescence.The repair of high-precision thin-walled structure additive manufacturing structural member is realized, and the generation of crack defects after repair welding is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of repairing high-temperature alloy additive manufacturing products, and more particularly to a method for repairing defects in additively manufactured high-temperature alloy products. Background Technology

[0002] With industrial development, high-performance materials are being widely adopted, the development cycle of equipment has been significantly shortened, and the development cost needs to be strictly controlled, which undoubtedly places higher demands and challenges on manufacturing technology.

[0003] For example, if a product's equipment compartment uses GH99 alloy for additive manufacturing, the structural components require high surface precision. Existing casting techniques are prone to defects such as shrinkage porosity and inclusions. If forging is used, die forging requires large-tonnage presses, and the high temperatures drastically shorten the lifespan of components like molds and worktables, significantly increasing the manufacturing cost per piece. For expensive metals like GH99 alloy with high mechanical properties, tool wear is severe, machining is difficult and time-consuming, and material utilization is low, greatly increasing manufacturing costs. Traditional manufacturing technologies struggle to efficiently and cost-effectively manufacture such structural components. Additive manufacturing technology, based on the discrete-stacking principle, melts and deposits metal material layer by layer using a predetermined heat source, directly forming high-performance structural components from a near-net-shape three-dimensional model. This represents a crucial direction for the future development of advanced manufacturing of structural components.

[0004] However, in the additive manufacturing process of complex thin-walled structural parts, the support structure is often not ideal, which can lead to defects such as product deformation and dents. Traditional welding methods often use manual argon arc welding, which is prone to cracking defects after welding and heat treatment. Currently, traditional welding methods are only used for welding of thick areas with a wall thickness of more than 1 mm or high-strength areas with internal reinforcing ribs. For thin-walled areas with a wall thickness of less than 1 mm and no internal support structure, it is difficult to avoid cracking, which seriously restricts the promotion of additive manufacturing technology to the field of complex, high-precision, and high-temperature alloys. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for repairing defects in additively manufactured high-temperature alloy products. This method can achieve the repair of high-precision thin-walled additively manufactured structural parts and effectively improve the generation of crack defects after welding repair.

[0006] This invention provides a method for repairing defects in additively manufactured high-temperature alloy products, comprising the following steps:

[0007] S1. Perform a 3D scan on the additively manufactured product and compare it with the 3D theoretical model to confirm the missing areas and thickness characteristics of the product.

[0008] S2. Mechanically grind and clean the areas with insufficient material.

[0009] S3. Use a handheld laser device and welding wire to fill and repair the missing area;

[0010] S4. Perform X-ray inspection on the repair site;

[0011] S5. Heat-treat the product after welding repair.

[0012] S6. Machin the excess weld height;

[0013] S7. Perform fluorescence detection on the repaired area.

[0014] It should be noted that the additively manufactured high-temperature alloy product is a thin-walled hollow sandwich structure with a thickness of ≤1mm in the thin-walled area, and the defect location of the product is on the outer surface of the product.

[0015] Specifically, the thickness characteristic of the defective area in step S1 is a depression, and the degree of depression is greater than 0.3 mm from the theoretical model.

[0016] For example, in step S3, the thickness of the welded area after repairing the defective area is greater than the thickness of the product body.

[0017] Furthermore, the product material is GH99, and the welding wire material is GH4099.

[0018] Specifically, the handheld laser device mentioned in step S3 is a fiber laser with a power of 1200W-1500W. The welding operator manually fills the wire, and the laser oscillation frequency is 50HZ with an oscillation amplitude of 2.5mm.

[0019] Preferably, the protective gas for the handheld laser device in step S3 is argon, with a flow rate of 20L / min-25L / min.

[0020] Furthermore, the heat treatment temperature of the product after the repair welding described in step S5 is 750℃-760℃, and the duration is 8-9 hours.

[0021] Specifically, the room temperature strength of the repaired weld location reaches 1100MPa, the high temperature strength at 700℃ reaches 630MPa, and the high temperature strength at 900℃ reaches 380MPa.

[0022] Preferably, the diameter of the welding wire in step S3 is 1.2 mm.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] 1. For the repair of defects in additive manufacturing high-temperature alloy products with thin-walled hollow sandwich structures with a thickness of ≤1mm in the thin-walled area, this invention uses a low-power handheld laser device, which is flexible and efficient. Furthermore, the welding operator manually fills the wire, inputs it intermittently, and manually controls the laser heat source. While ensuring welding quality, this method minimizes the welding heat input, reduces the amount of filler wire, reduces welding deformation, and effectively avoids the generation of weld cracks.

[0025] 2. This invention involves heat treatment at 750℃-760℃ for 8 hours after welding repair of thin-walled GH99 high-temperature alloy structures, which effectively eliminates welding stress and prevents cracks from forming at the weld location.

[0026] 3. The defect repair method of the present invention is used to process additive manufacturing high-temperature alloy products. The internal and external quality of the weld are detected by X-ray detection and fluorescence detection, respectively. The weld is free of defects. The tensile strength test shows that the room temperature strength reaches 1100MPa, the high temperature strength at 700℃ reaches 630MPa, and the high temperature strength at 900℃ reaches 380MPa.

[0027] 4. The defect repair method of the present invention enables high-quality and rapid repair of high-precision, thin-walled, and easily deformable high-temperature alloy products through additive manufacturing. It fills the gap in defect repair for high-precision thin-walled high-temperature alloy products, avoids the direct scrapping of high-precision products due to local defects after additive manufacturing, and greatly reduces the manufacturing cost of high-precision thin-walled high-temperature alloy products.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 This is a schematic diagram of the handheld laser device for welding repair according to the present invention.

[0031] Figure 2a A schematic diagram of the external shape of a high-precision thin-walled structure of a high-temperature alloy.

[0032] Figure 2b A 3D view of the high-precision thin-walled structure of a high-temperature alloy;

[0033] Figure 3 This is a cross-sectional view of a high-precision thin-walled structure of a high-temperature alloy.

[0034] Figure 4a This is a photo taken before the repair of a high-precision thin-walled structure made of high-temperature alloy.

[0035] Figure 4b Photos showing the repaired high-precision thin-walled structure made of high-temperature alloy;

[0036] Figure 5a Microscopic images of the high-precision thin-walled structure of a high-temperature alloy before repair;

[0037] Figure 5b for Figure 5a Microscopic images of the high-precision thin-walled structure of high-temperature alloy after repair;

[0038] Figure 6a This is a photograph of the thin-walled structure after repair and polishing in Example 1;

[0039] Figure 6b This is a photo of the thin-walled structure after repair and polishing, as shown in Comparative Example 2.

[0040] Figure label:

[0041] 10 - Handheld laser device; 20 - Welding wire; 30 - Product body; 40 - Defective area on the recessed surface of the product; 50 - Filler material after repair welding. Detailed Implementation

[0042] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form 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 intended to limit the scope of the present invention.

[0043] In the additive manufacturing process, complex thin-walled structural parts are prone to defects such as deformation and dents due to inadequate support structure constraints. Traditional welding repair methods often employ manual argon arc welding, which easily leads to crack defects after welding and heat treatment. Currently, traditional welding repair methods are only used for welding of areas with a wall thickness exceeding 1mm or high-strength areas with internal reinforcing ribs. However, for thin-walled areas with a wall thickness of less than 1mm and no internal support structure, it is difficult to avoid cracking, which seriously restricts the promotion of additive manufacturing technology to the field of complex, high-precision, and high-temperature alloys.

[0044] To achieve high-precision repair of additively manufactured thin-walled structural components and effectively reduce the occurrence of crack defects after welding repair, a specific embodiment of the present invention discloses a method for repairing defects in additively manufactured high-temperature alloy products, comprising the following steps:

[0045] S1. Perform a 3D scan on the additively manufactured product and compare it with the 3D theoretical model to confirm the missing areas and thickness characteristics of the product.

[0046] S2. Mechanically grind and clean the areas with insufficient material.

[0047] S3. Use a handheld laser device and welding wire to fill and repair the missing area;

[0048] S4. Perform X-ray inspection on the repair site;

[0049] S5. Heat-treat the product after welding repair.

[0050] S6. Machin the excess weld height;

[0051] S7. Perform fluorescence detection on the repaired area.

[0052] It should be noted that the additively manufactured high-temperature alloy product is a thin-walled hollow sandwich structure with a thickness of ≤1mm in the thin-walled area. The defect location is on the outer surface of the product, and the space for repair welding is well accessible.

[0053] For the repair of defects in additive manufacturing high-temperature alloy products with thin-walled hollow sandwich structures with a thickness of ≤1mm in the thin-walled area, this invention uses a low-power handheld laser device, which is flexible and efficient. Furthermore, the welding operator manually fills the wire, inputs it intermittently, and manually controls the laser heat source. This ensures welding quality while minimizing the welding heat input, reducing the amount of filler wire, reducing welding deformation, and effectively avoiding the generation of weld cracks.

[0054] Specifically, the thickness characteristic of the defective area in step S1 is a depression, and the degree of depression is greater than 0.3 mm from the theoretical model.

[0055] Further, in step S2, before the repair welding operation, the surface of the missing area is mechanically ground and cleaned, and wiped with alcohol to remove the oxide film and oil stains on the surface of the area to be repaired, so as to prevent porosity and slag inclusions after repair welding.

[0056] For example, the product material is GH99, the welding wire material is GH4099, and the welding wire diameter is 1.2mm.

[0057] Specifically, the handheld laser device mentioned in step S3 is a fiber laser with a power of 1200W-1500W. The welding operator manually fills the wire, the laser oscillation frequency is 50HZ, and the oscillation amplitude is 2.5mm. The welding process parameters are obtained through welding feasibility verification based on the product material and wall thickness.

[0058] Furthermore, the welding process uses continuous laser power, which results in high weld strength and good surface finish.

[0059] Preferably, the protective gas for the handheld laser device in step S3 is argon, with a flow rate of 20L / min-25L / min.

[0060] Furthermore, in step S3, the thickness of the repair welding location after the defective area of ​​the product is greater than the thickness of the main body.

[0061] In one possible design, the thin-walled product body is 1mm thick. It is repaired using a handheld laser device. The repair is stopped after visually inspecting that the thickness of the repaired welding position is higher than the surface of the base material. The thickness of the repaired welding position is greater than 1mm.

[0062] Further, step S4 involves X-ray inspection of the repaired area to detect whether there are porosity or lack of fusion defects inside the weld. If defects are found in the weld, they need to be removed and then repaired. Before heat treatment, ensure that the weld is qualified to avoid repeated heat treatment and reduce costs.

[0063] Further, in step S5, the entire product after welding is subjected to heat treatment at a temperature of 750℃-760℃ for 8-9 hours; after heat treatment, it is cooled to room temperature in the furnace.

[0064] Handheld laser welding can melt the welding wire and fill the weld with a small heat input, effectively reducing the internal stress of the weld. At the same time, through heat treatment, fine strengthening phases can be precipitated in the austenite grains of the alloy, thereby improving the room temperature and high temperature strength of the alloy. The microstructure of the weld repair area is austenite with dispersed compounds, and the precipitated strengthening phases are VC, Ni3Al, Ni3Ti, and Ni3(Al·Ti).

[0065] After cooling, the excess height of the weld repair is processed. The assembly surface is machined using a machine tool, while the non-assembly surface is smoothed by grinding with an angle grinder. During the grinding process, the wall thickness is measured using a wall thickness gauge. Grinding is stopped after the thickness of the product body is reached, and a 3D scan is used to compare it with the design model again to confirm that there are no depressions on the outer surface of the product. After grinding, the surface of the product is flat, which facilitates the observation of surface cracks and defects in the subsequent fluorescent detection process.

[0066] Furthermore, the processed product is subjected to fluorescence detection to check for the presence of microcracks on the product surface; the microcracks are fish-scale patterns.

[0067] Compared with existing technologies, the repair method for high-precision thin-walled additive manufacturing structural components provided in this embodiment can achieve high-quality, low-cost, and rapid repair of high-temperature alloy products with high precision, small wall thickness, and easy deformation through additive manufacturing.

[0068] The internal and external quality of the weld were inspected by X-ray and fluorescence detection, respectively. The weld was found to be defect-free. Tensile strength tests showed that the strength reached 1100 MPa at room temperature, 630 MPa at 700℃, and 380 MPa at 900℃.

[0069] The following specific embodiments illustrate the repair effect of the present invention in repairing defects in high-precision thin-walled structure additive manufacturing.

[0070] The handheld laser device used in this embodiment is model (FCA1500).

[0071] Example 1

[0072] Figure 2 shows a high-precision thin-walled structure, which is an additive manufacturing high-temperature alloy product. Its main body is a thin-walled hollow structure. After removing the support, the surface of the product is characterized by a depression, and the degree of depression is greater than 0.3 mm from the theoretical model. The defect is located on the outer surface of the product, and the space for repair welding is well accessible.

[0073] The product material is GH99, the welding wire material is GH4099, and the product body wall thickness is 1mm.

[0074] The specific repair process is as follows:

[0075] S1. First, a tracking 3D scanner is used to perform a 3D scan on the outer surface of the additive manufacturing product and compare it with the 3D design model to identify and mark the areas on the outer surface of the product where the amount of depression exceeds 0.3mm compared with the theoretical model.

[0076] S2. Then, treat the surface of the area to be repaired: use a clean wire brush to mechanically grind and clean the area with missing material to reveal its metallic luster, and wipe the surface with anhydrous ethanol.

[0077] S3. Based on the product wall thickness, select a welding wire diameter of 1.2mm; use a handheld laser device and welding wire to fill and repair the missing parts.

[0078] Based on the product material and wall thickness, the welding feasibility was verified, and the welding parameters were determined as follows: laser power of 1200W-1500W, manual wire filling by the welding operator, laser oscillation frequency of 50HZ, oscillation amplitude of 2.5mm; the protective gas for the handheld laser is argon, with a gas flow rate of 20L / min-25L / min.

[0079] Welding was stopped once the dented area was visually inspected and found to be completely covered and higher than the surface of the body.

[0080] S4. After the repair welding is completed, X-ray inspection is carried out on the repaired area to check for porosity and lack of fusion defects inside the weld. If the inspection fails, the defective area of ​​the weld needs to be excavated and re-welded. The repair welding qualification rate is over 98%. If the inspection is qualified, the product is heat treated.

[0081] S5. Perform heat treatment on the product at a temperature of 750℃-760℃ for 8 hours; eliminate internal stress and improve the mechanical properties of the product.

[0082] S6. Use an angle grinder to smooth the excess height of the weld. During the grinding process, measure the wall thickness with a wall thickness gauge. Stop grinding after the thickness of the product body is reached. Use a 3D scan to compare with the design model again to confirm that there are no dents on the outer surface of the product.

[0083] S7. Perform fluorescence detection on the repaired area. If there are no cracks on the surface, the repair is complete, and the first-time repair pass rate reaches 100%.

[0084] The appearance of the product before and after repair is shown in Figure 4, and the microstructure of the product before and after repair is shown in Figure 5. The tensile strength test results show that the room temperature strength reaches 1100 MPa, the high temperature strength at 700℃ reaches 630 MPa, and the high temperature strength at 900℃ reaches 380 MPa.

[0085] Comparative Example 1

[0086] For the 1mm thick additive manufacturing high-temperature alloy welding test plates 1-1, 1-1, and 1-3, made of GH99, a pit with a depth of 0.3-0.5mm was machined on the surface, and handheld laser welding was performed to repair the weld using the method described in Example 1. After the repair welding, the weld was ground smooth. The test samples were not heat-treated, and tensile test specimens were processed for mechanical property testing. The test results are shown in Table 1.

[0087] Table 1. Results of mechanical property testing on welded test plates of Comparative Example 1 and Example 1 after repair welding.

[0088]

[0089] As can be seen from Table 1, the strength of the untreated sample is significantly different from that of the heat-treated sample. During the heat treatment process, a strengthening phase will precipitate in the austenite grains, which can significantly improve the room temperature and high temperature performance of the sample.

[0090] Comparative Example 2

[0091] For the same product as in Example 1, manual argon arc welding was used to repair the dented area. The welding current was 40-50A, the tungsten electrode diameter was 2.0mm, the welding wire diameter was 1.2mm, and the argon flow rate was 10L / min.

[0092] After welding, due to the large heat input of argon arc welding, the thin-walled area was severely deformed; at the same time, the weld passed the X-ray inspection, and after heat treatment and grinding, microcracks were found to be visible to the naked eye.

[0093] Figure 6 shows photos of the weld repair locations of the products after welding, heat treatment, and grinding in Example 1 and Comparative Example 2. It can be seen that after the defect was repaired using the method of the present invention, there were no cracks on the surface of Example 1, while the cracks in Comparative Example 2, which used the traditional repair method, were obvious.

[0094] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for repairing defects in additively manufactured high-temperature alloy products, characterized in that, The additively manufactured high-temperature alloy product is a thin-walled hollow sandwich structure, with a thin-walled region thickness ≤1mm. The defect location is on the outer surface of the product. The product material is GH99. The process includes the following steps: S1. Perform a 3D scan on the additively manufactured product and compare it with the 3D theoretical model to confirm the missing area and thickness characteristics of the product; the thickness characteristic of the missing area is a depression, and the depression degree is greater than 0.3mm from the theoretical model. S2. Mechanically grind and clean the areas with insufficient material. S3. A handheld laser device and welding wire are used to fill and repair the missing area. The welding process uses continuous laser power. The handheld laser device is a fiber laser with a power of 1200W-1500W. The welding operator manually fills the wire. The laser oscillation frequency is 50HZ and the oscillation amplitude is 2.5mm. The shielding gas of the handheld laser device is argon with a flow rate of 20L / min-25L / min. The welding wire material is GH4099. S4. Perform X-ray inspection on the repair site; S5. Heat treatment is performed on the product after welding repair; the heat treatment temperature of the product after welding repair is 750℃-760℃, and the duration is 8-9 hours. S6. Machining the excess height of the weld repair; the assembly surface is machined by machine tool, and the non-assembly surface is smoothed by angle grinder. During the grinding process, the wall thickness is measured by wall thickness gauge and grinding is stopped after the thickness of the product body is reached. S7. Perform fluorescence detection on the repaired area to detect whether there are microcracks on the product surface, wherein the microcracks are fish scale patterns.

2. The method for repairing defects in additively manufactured high-temperature alloy products according to claim 1, characterized in that, In step S3, after repairing the defective area of ​​the product, the thickness of the welded area is greater than the thickness of the main body.

3. The method for repairing defects in additively manufactured high-temperature alloy products according to claim 1, characterized in that, The heat treatment temperature of the product after the repair welding in step S5 is 750℃-760℃, and the duration is 8 hours.

4. The method for repairing defects in additively manufactured high-temperature alloy products according to claim 1, characterized in that, The strength at room temperature of the repaired weld site reaches 1100MPa, the strength at 700℃ reaches 630MPa, and the strength at 900℃ reaches 380MPa.

5. The method for repairing defects in additively manufactured high-temperature alloy products according to claim 1, characterized in that, The diameter of the welding wire in step S3 is 1.2 mm.

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