Process method for preparing erosion-resistant layer on surface of high-speed pump diffuser runner opening

Abstract

The invention belongs to the technical field of material additive manufacturing and surface engineering, and particularly relates to a process method for preparing an erosion-resistant layer on the surface of a high-speed pump diffuser runner opening. According to the method, a cold metal transition welding technology is adopted, cobalt-based alloy with high corrosion resistance is selected as a surfacing material and applied to the surface of the high-speed pump diffuser runner opening in a surfacing mode, an erosion-resistant surfacing layer which is free of metallurgical defects and high in hardness is constructed, and therefore the service life of a diffuser is effectively prolonged. According to the technological method, through precise welding parameter regulation and control and scientific selection of materials, the erosion resistance of the surface of the diffuser runner opening of the high-speed pump is remarkably improved, an efficient and reliable surface strengthening solution is provided for the industrial field, and the technological method has important technological innovation value and application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of material additive manufacturing and surface engineering technology, and specifically is a process method for preparing an erosion-resistant layer on the surface of a high-speed pump diffuser flow channel outlet. Background Art

[0002] As the core equipment in the chemical industry, the efficient and stable operation of high-speed pumps is crucial to the production process. Among them, the diffuser, as a key component of the high-speed pump, bears the important responsibility of converting kinetic energy and increasing fluid pressure. Its performance is directly related to the overall efficiency and operational stability of the pump. In view of this, it is particularly necessary to develop a surface strengthening process for the diffuser flow channel, aiming to significantly improve the erosion resistance, corrosion resistance and fatigue strength properties of the diffuser, and ensure that the high-speed pump can operate stably and durably in complex and harsh working conditions. At present, diffusers are mostly made of high-quality stainless steel materials such as 304, 316, and 2205. These materials are widely favored for their excellent corrosion resistance. However, the hardness of stainless steel itself is relatively low. When faced with strong erosion of high-speed fluids, it is prone to wear and tear, and its erosion resistance needs to be strengthened. To this end, it is urgent to explore effective material strengthening technology to enhance the erosion resistance of the diffuser surface, while taking into account the corrosiveness of the medium solution, and comprehensively optimize the surface quality of the diffuser, thereby significantly extending its service life and ensuring the long-term operation of the high-speed pump system. The development of this surface strengthening process not only focuses on improving the physical properties of the diffuser, but also requires in-depth consideration of the interaction between the material and the medium to ensure that while enhancing the erosion resistance, its anti-corrosion performance will not be weakened, and strive to maximize the performance of the diffuser under complex working conditions, thereby promoting the innovation and development of high-speed pump technology. Summary of the invention

[0003] In view of the harsh working environment faced by the diffuser and the complex media it contacts, conventional material enhancement solutions often fail to meet the requirements of its long-term stable operation. The purpose of the present invention is to provide a process for preparing an erosion-resistant layer on the surface of the diffuser flow channel of a high-speed pump, which adopts an innovative surface strengthening process and is specially designed for the diffuser flow channel of a high-speed pump, and is used to significantly enhance the erosion resistance of the diffuser flow channel of a high-speed pump.

[0004] The technical solution of the present invention is as follows:

[0005] A process for preparing an erosion-resistant layer on the surface of a high-speed pump diffuser flow channel, the method adopts cold metal transition welding technology, selects a cobalt-based alloy with strong corrosion resistance as a surfacing material, and applies surfacing to the surface of the high-speed pump diffuser flow channel to form a high-quality erosion-resistant surfacing layer without metallurgical defects, and specifically comprises the following steps:

[0006] (1) Surface pretreatment and evaluation, cleaning and measurement: Thoroughly remove surface dirt, carefully inspect the erosion damage, accurately measure the dimensions of damaged and intact areas, and ensure that data records are accurate;

[0007] (2) Nondestructive testing: Use PT flaw detection technology to comprehensively check the structural integrity of the diffuser and eliminate potential crack hazards;

[0008] (3) Surface pretreatment and activation: Finely grind the eroded area until the silvery white metallic luster is exposed, completely remove the surface fatigue layer, and create a high-quality foundation for subsequent surfacing;

[0009] (4) Cooling strategy optimization: partially immerse the diffuser in the coolant, exposing only the repair area, effectively preventing deformation caused by high temperature and ensuring dimensional stability during the cladding process;

[0010] (5) Precision cladding process, precise control of welding parameters: current 100-130A, voltage 10-15V, wire extension 8-12mm, overlap rate 45%-60%, cladding speed 12-15mm / s; use 99.99% pure argon as shielding gas, adjust the flow rate to 10-15L / min, wire feeding speed 0.7-1.2m / min, the thickness of the cladding layer exceeds the intact area by at least 1.5mm, and sufficient processing allowance is reserved;

[0011] (6) Strict quality inspection: After the repaired area cools down to room temperature, perform PT inspection and record the inspection results in detail; if any metallurgical defects are found, perform grinding and repair welding procedures immediately until the quality standards are met;

[0012] (7) Precision cutting and re-testing: Precision grinding is performed according to the drawing specifications to ensure that the repair area is perfectly integrated with the whole; then, a secondary PT flaw detection is performed on the key diffuser flow channel to strictly eliminate the existence of any metallurgical defects.

[0013] In the process method for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening, the diffuser is made of stainless steel.

[0014] In the process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening, in step (3), during the surface pretreatment upgrade process, an angle grinder or a straight grinder is used for fine grinding.

[0015] In the process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening, in step (4) the cooling strategy optimization process, the diffuser is partially immersed in a coolant before surfacing to prevent high-temperature deformation.

[0016] In the process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening, in the precision surfacing process of step (5), the welding wire used for surfacing is a cobalt-based alloy, and the chemical composition of the welding wire is, by mass percentage, C 0.2-1.4, Cr 28-40, Si 0.2-2, Ni 0-3, Fe 0-3, Mn0.5-2, Mo 0-1.5, W 3.5-5.5, and Co balance.

[0017] In the process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening, during the precision surfacing process of step (5), the thickness of the surfacing layer is precisely controlled to be 1 to 3 mm.

[0018] The design concept of the present invention is:

[0019] This invention is located at the intersection of materials science and surface engineering technology, focusing on the development of an innovative surface strengthening process, aiming to significantly improve the erosion resistance of the flow channel of the high-speed pump diffuser. Specifically, this method focuses on using advanced additive manufacturing technology to accurately modify the surface of the key part of the high-speed pump diffuser, the flow channel, to enhance its ability to resist high-speed fluid erosion, thereby greatly extending the service life of the diffuser and ensuring the stable operation and efficient performance of the high-speed pump system under harsh working conditions.

[0020] The present invention innovatively uses advanced cold metal transition welding technology (CMT) to build a high-performance erosion-resistant layer on the surface of the substrate. Through the unique low heat input characteristics of cold metal transition welding, the cobalt-based alloy is precisely deposited on the substrate to form a solid protective layer. The CMT cladding layer and the base material are closely bonded at the metallurgical level, and its bonding strength reaches or exceeds 85% of the original base material strength, while maintaining a low dilution rate of 5% to 10%, ensuring the material properties of the erosion-resistant layer. The key advantage of cold metal transition welding technology (CMT) lies in its ability to precisely control the welding process. The system can intelligently identify the initial moment of arc generation, and then automatically reduce the welding current until the arc disappears, and then adjust the pulsed wire feed rate. This process optimizes the transition morphology of the wire droplet and achieves a more stable droplet separation. After the droplet detaches from the wire, the digital control system quickly recovers and increases the welding current, pushing the wire forward, and then re-stimulating the welding arc, repeating the cycle to start the next round of welding cycle. Thanks to this "cold-hot-cold" dynamic balance mechanism, the welding heat input is greatly reduced, thereby reducing the conduction of heat into the workpiece and avoiding the expansion of the heat-affected zone.

[0021] Although traditional surfacing technology can locally strengthen materials, its limitation is that it is difficult to ensure the consistency of surfacing quality. In addition, the side effects that may be induced during the surfacing process, such as component deformation, high dilution rate, high stress concentration and cracks in the heat-affected zone, seriously restrict the reliability and service life of the diffuser. The core of the present invention is to use the cold metal transition (CMT) welding process, combined with selected alloy welding wire, to accurately build a layer of erosion-resistant layer that forms a metallurgical grade bond with the base material in the key area of ​​the diffuser flow channel. Through this process, the prepared erosion-resistant layer not only has the high-quality characteristics of no welding defects, but also shows an excellent hardness higher than HV400, effectively enhancing the ability of the diffuser to resist high-speed fluid erosion, while significantly reducing welding residual stress, avoiding the various disadvantages brought about by traditional surfacing technology. The process method of the present invention can not only greatly extend the service life of the diffuser, but also ensure the stability and efficiency of the high-speed pump under complex working conditions, providing strong technical support for high-speed pump equipment in the fields of chemical industry, energy, environmental protection, etc.

[0022] Compared with the existing welding technology, the present invention has the following advantages and beneficial effects:

[0023] 1. Innovative preparation of erosion-resistant layer: With precisely controlled process parameters and preferred alloy materials, the present invention successfully constructs a high-hardness erosion-resistant layer with a thickness of not less than 1 mm and a hardness exceeding the HV400 standard on the surface of the diffuser flow channel, which significantly improves the wear resistance of the components under harsh working conditions and ensures long-term operation stability and reliability.

[0024] 2. Excellent metallurgical bonding quality: The erosion-resistant layer of the present invention forms a stable metallurgical bond with the base material, and its structure is dense, eliminating common defects such as pores, cracks and inclusions. This high-quality feature has been widely praised by actual users, proving its excellent performance in complex application environments.

[0025] 3. Low heat input surfacing technology: The surfacing process adopted by the present invention significantly reduces the heat input, effectively avoids the deformation problem of the diffuser due to overheating, ensures the original geometric accuracy and functionality of the diffuser, and enables it to maintain a good working condition after surfacing without additional correction or processing.

[0026] 4. Wide applicability and flexibility: Whether it is manual operation or automated production, the present invention can respond flexibly and is suitable for various needs from small-scale repairs to large-area coverage. It shows extremely high adaptability and operating efficiency, and provides a comprehensive solution for repair projects of different scales.

[0027] 5. Efficient production recovery and cost savings: With the help of the efficient surfacing technology of the present invention, enterprises can quickly restore the surface performance of the diffuser flow channel in a very short time, which not only significantly extends the service life of the diffuser, but also greatly reduces the high cost caused by frequent replacement of new parts, creating significant economic benefits for the enterprise, while ensuring the continuity and market competitiveness of the production line.

[0028] 6. Quality improvement: The cobalt-based alloy material selected in the present invention not only has improved erosion resistance, but also has significantly improved corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a physical picture of the damaged diffuser that needs to be repaired.

[0030] Figure 2 This is a diagram marking the locations prone to erosion at the diffuser flow channel opening.

[0031] Figure 3 This is the metallographic structure diagram of the interface between the erosion-resistant cladding layer and the substrate.

[0032] Figure 4 This is the metallographic diagram of the erosion-resistant layer.

[0033] Figure 5 This is the Vickers hardness diagram of the diffuser substrate along the cladding layer direction.

[0034] Figure 6 The following are pictures of the actual objects restored according to the embodiment of the present invention, wherein (a) is the overall picture and (b) is the partial picture. DETAILED DESCRIPTION

[0035] In the specific implementation process, the present invention proposes a process method for preparing an erosion-resistant layer on the surface of the flow channel outlet of a high-speed pump diffuser. The method adopts CMT welding technology, selects a cobalt-based alloy with strong corrosion resistance as a surfacing material, and accurately surfacing welds it on the surface of the flow channel outlet of the diffuser to construct a layer of erosion-resistant surfacing layer with no metallurgical defects and high hardness, thereby effectively extending the service life of the diffuser.

[0036] like Figure 2 As shown, for the easily eroded position of the diffuser flow channel opening, the specific steps of the method of the present invention are as follows:

[0037] (1) Surface pretreatment and evaluation, cleaning and measurement: Thoroughly remove surface dirt, carefully inspect the erosion damage, accurately measure the dimensions of damaged and intact areas, and ensure that data records are accurate.

[0038] (2) Nondestructive testing: Use PT flaw detection technology to comprehensively check the structural integrity of the diffuser and eliminate potential crack hazards.

[0039] (3) Upgrade the surface pretreatment, using professional tools such as angle grinders or straight grinders to finely grind the eroded area until the silver-white metallic luster is exposed, completely removing the surface fatigue layer and creating a high-quality foundation for subsequent surfacing.

[0040] (4) The cooling strategy is optimized by partially immersing the diffuser in the coolant and exposing only the repair area, which effectively prevents deformation caused by high temperature and ensures dimensional stability during the cladding process.

[0041] (5) Precision cladding process, precise control of welding parameters: set the welding current at 100-130A, maintain the welding voltage at 10-15V, and control the wire extension length at 8-12mm to ensure arc stability and smoothness of droplet transition. The weld overlap rate is optimized to 45%-60%, and the cladding speed is 12-15mm / s to balance the cladding efficiency and interlayer bonding quality. Use 99.99% pure argon as the shielding gas, adjust the flow rate to 10-15L / min, and the wire feeding speed is 0.7-1.2m / min.

[0042] Shielding gas and surfacing materials: High-purity argon gas with a volume purity of 99.99% is used as shielding gas, and the gas flow rate is adjusted to 10-15L / min to isolate the welding area, avoid oxidation, and ensure the purity and integrity of the surfacing layer. The surfacing material is selected from cobalt-based alloy, which has excellent corrosion resistance and wear resistance. The wire feeding speed is controlled at 0.7-1.2m / min to ensure the uniformity and density of the surfacing layer.

[0043] Thickness of cladding layer: The thickness of cladding layer is precisely controlled within 1-3mm, which not only meets the requirements of erosion resistance, but also takes into account the overall structure and weight balance of the diffuser. The thickness of cladding layer exceeds the intact area by at least 1.5mm (sufficient processing allowance is reserved).

[0044] (6) Strict quality inspection: After the repaired area cools down to room temperature, perform PT testing and record the results in detail. Once any metallurgical defects are found, they will be immediately polished and removed, followed by repair welding until the quality standards are met.

[0045] (7) Precision cutting and re-testing: Precision grinding is performed according to the drawing specifications to ensure that the repaired area is perfectly integrated with the whole. Subsequently, a secondary PT flaw detection is performed on the key diffuser flow channel to strictly eliminate any metallurgical defects.

[0046] The technical advantages of the present invention are:

[0047] High-quality metallurgical bonding: The cladding layer forms a strong metallurgical bond with the base material, with a dense structure and no welding defects such as pores and cracks, ensuring structural stability and performance consistency under long-term operating conditions.

[0048] Low heat input and deformation control: CMT technology significantly reduces the heat input. The current returns to zero instantly during droplet transfer, effectively reducing the heat affected area. By partially immersing the diffuser in coolant for surfacing, thermal deformation is further suppressed, maintaining the original geometry and mechanical properties of the diffuser.

[0049] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0050] Example:

[0051] like Figure 1 As shown in the figure, the diffuser of a high-speed pump with the position number of G-1209 in a chemical enterprise in Zhejiang Province is made of 2205 duplex stainless steel, and the flow channel is severely eroded. Although the erosion area is relatively small, given that the working speed of the equipment is as high as 2950r / min, this local damage poses a major threat to the normal operation of the entire device, directly affecting production efficiency and safety. Faced with this challenge, the company decisively adopted the innovative repair process of the present invention to carry out precise additive repair of the damaged parts and their surrounding areas. By using cold metal transition welding technology, combined with optimized alloy materials and process parameters, a high-hardness, erosion-resistant surfacing layer was successfully constructed on the surface of the flow channel, effectively restoring the original geometric shape and functional performance of the diffuser. After the repair was completed, after rigorous testing and on-site verification, the various operating indicators of the flow channel of the G-1209 high-speed pump diffuser were completely restored to normal, the device operated smoothly, and no abnormal signs appeared, indicating that this repair work was a complete success. This application fully demonstrated the remarkable effect of the present invention in solving the problem of local erosion of high-speed rotating equipment, and provided a strong technical guarantee for the rapid recovery and continuous and stable operation of enterprise equipment.

[0052] The specific steps of this embodiment are as follows:

[0053] 1. Surface pretreatment and size verification: thoroughly clean the diffuser surface and use special organic solvents to thoroughly remove oil and impurities in the repair area. Accurately measure the dimensions of damaged and intact areas to ensure the accuracy of subsequent repair work.

[0054] 2. Assessment and pretreatment of the eroded area: Carefully inspect the eroded area and finely polish the damaged area and its adjacent areas until the bright silver-white metal base color is exposed to prepare a clean and smooth surface for surfacing.

[0055] 3. Non-destructive testing confirmation: Use PT non-destructive testing technology to conduct a comprehensive inspection of the polished area to ensure that there are no hidden defects before repair and to ensure the quality of the repair.

[0056] 4. Pre-set coolant: place the diffuser to be repaired in the coolant, only expose the repaired part, effectively control the thermal deformation during the cladding process, and maintain the original geometric accuracy. Coolant brand: Fronius FCL10 welding gun COOLING LIQUID coolant.

[0057] 5. CMT cladding process was implemented. The welding wire used for cladding was a specific cobalt-based alloy with the chemical composition (mass %) of C0.3, Cr 39.5, Si 0.12, Ni 2.34, Fe 1.9, Mn 1.33, Mo 1.2, W 4.4, and Co balance. The welding parameters were set as follows: current 110A, voltage 13V, welding speed 10mm / s, wire diameter 1.2mm, dry extension length 10mm, overlap rate 55%, shielding gas used pure argon with a volume purity of 99.99%, flow rate 15L / min, and wire feeding speed 0.9m / min.

[0058] 6. Control the height of the additive layer, and make sure that the surfacing additive part is at least 1.5mm higher than the intact area, leaving sufficient allowance for subsequent processing.

[0059] 7. Cooling and quality inspection: After the diffuser cools to room temperature, perform PT inspection on the added parts to strictly check for any possible defects such as pores and cracks.

[0060] 8. Precision grinding: According to the drawing specifications, the repair area is finely ground to ensure that the surface finish reaches the standard of Ra0.8μm.

[0061] 9. Final non-destructive testing: After grinding, a comprehensive PT flaw detection is performed again to confirm that there are no metallurgical defects on the surface of the repaired diffuser to ensure processing quality and safety.

[0062] like Figure 3 , Figure 4 As shown in the figure, through metallographic observation, it is clearly seen that a solid metallurgical bond is formed between the erosion-resistant layer manufactured by additive manufacturing and the base material, and its internal structure presents a uniform and fine microstructure, demonstrating excellent material consistency and microstructural stability. In this embodiment, a high-hardness erosion-resistant layer is successfully constructed on the surface of the high-speed pump diffuser flow channel, with a thickness of about 2.5 mm. After hardness testing, the average value reaches HV 0.2 About 440, indicating that the erosion-resistant layer has an excellent hardness level and can effectively resist the impact and wear of high-speed fluid, significantly improving the service performance and service life of the diffuser under harsh working conditions.

[0063] like Figure 5As shown, a total of 3 columns of points are taken, 11 points in each column, and the uniform distribution distance is 0.5mm. From the Vickers hardness diagram of the diffuser substrate along the cladding layer, it can be seen that the hardness of the substrate along the cladding layer gradually increases and gradually approaches a balance trend. The highest hardness of the cladding layer is HV 0.2 486, the hardness is significantly improved, which is conducive to improving the erosion resistance.

[0064] like Figure 6 As shown, it can be seen from the actual repair picture of the embodiment of the present invention that the surface of the diffuser is smooth and bright after repair, without welding defects, and meets the use requirements after inspection by the quality inspection department, and all operating indicators are normal.

[0065] In summary, the erosion-resistant layer prepared in this embodiment not only exhibits metallurgical bonding with the base material in terms of microstructure, but also exhibits high hardness and excellent erosion resistance in terms of macroscopic performance, providing strong technical support for the surface strengthening and performance optimization of high-speed pump diffusers. The process method proposed in the present invention achieves a significant improvement in the erosion resistance of the surface of the flow channel of a high-speed pump diffuser through precise welding parameter control and scientific material selection, providing an efficient and reliable surface strengthening solution for the industrial field, and has important technical innovation value and application prospects.

Claims

1. A process for preparing an erosion-resistant layer on the surface of a high-speed pump diffuser flow channel, characterized in that: The method adopts cold metal transfer welding technology, selects a cobalt-based alloy with strong corrosion resistance as a surfacing material, and applies the surfacing to the surface of the high-speed pump diffuser flow channel to form a high-quality erosion-resistant surfacing layer without metallurgical defects. The method specifically includes the following steps: (1) Surface pretreatment and evaluation, cleaning and measurement: Thoroughly remove surface dirt, carefully inspect the erosion damage, accurately measure the dimensions of damaged and intact areas, and ensure that data records are accurate; (2) Nondestructive testing: Use PT flaw detection technology to comprehensively check the structural integrity of the diffuser and eliminate potential crack hazards; (3) Surface pretreatment and activation: Finely grind the eroded area until the silvery white metallic luster is exposed, completely remove the surface fatigue layer, and create a high-quality foundation for subsequent surfacing; (4) Cooling strategy optimization: partially immerse the diffuser in the coolant, exposing only the repair area, effectively preventing deformation caused by high temperature and ensuring dimensional stability during the cladding process; (5) Precision cladding process, precise control of welding parameters: current 100-130A, voltage 10-15V, wire extension 8-12mm, overlap rate 45%-60%, cladding speed 12-15mm / s; use 99.99% pure argon as shielding gas, adjust the flow rate to 10-15L / min, wire feeding speed 0.7-1.2m / min, the thickness of the cladding layer exceeds the intact area by at least 1.5mm, and sufficient processing allowance is reserved; (6) Strict quality inspection: After the repaired area cools down to room temperature, perform PT inspection and record the inspection results in detail; if any metallurgical defects are found, perform grinding and repair welding procedures immediately until the quality standards are met; (7) Precision cutting and re-testing: Precision grinding is performed according to the drawing specifications to ensure that the repair area is perfectly integrated with the whole; then, a secondary PT flaw detection is performed on the key diffuser flow channel to strictly eliminate the existence of any metallurgical defects.

2. The process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening according to claim 1, characterized in that: The diffuser is made of stainless steel.

3. The process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening according to claim 1, characterized in that: During the surface pretreatment upgrade process in step (3), fine grinding is performed using an angle grinder or a straight grinder.

4. The process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening according to claim 1, characterized in that: During the cooling strategy optimization process in step (4), the diffuser is partially immersed in the coolant before surfacing to prevent high-temperature deformation.

5. The process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening according to claim 1, characterized in that: In the precision surfacing process of step (5), the welding wire used for surfacing is a cobalt-based alloy, and the chemical composition of the welding wire is, by mass percentage, C 0.2-1.4, Cr 28-40, Si 0.2-2, Ni 0-3, Fe 0-3, Mn 0.5-2, Mo 0-1.5, W 3.5-5.5, and Co balance.

6. The process for preparing the erosion-resistant layer on the surface of the diffuser flow channel opening according to claim 1, characterized in that: During the precision cladding process in step (5), the thickness of the cladding layer is precisely controlled to be 1 to 3 mm.

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