Laser forging repair method and applications thereof
Patent Information
- Application Number
- CN202511472976.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-15
- Publication Date
- 2026-09-08
AI Technical Summary
[0002]航空发动机及燃气轮机高温合金支板在极端工况下易产生裂纹、烧蚀等损伤，直接更换成本高昂
本发明提供的方法，通过熔池凝固出现后的0.1~0.4s之后再进行高频微锻击，能实现动态枝晶破碎与异质形核，细化修复区平均晶粒尺寸，降低气孔率，彻底解决枝晶粗化与缺陷聚集问题。本发明特别是在凝固出现后的特定一段时间再进行微锻击，能够改变熔池流动行为，使得高温固相区发生塑性变形与晶粒细化，相对于激光熔覆与微锻击同步进行，能使得熔覆层组织均匀性与力学性能更好。
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Figure CN122707124A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of high-temperature alloy component repair, and more specifically, to a laser melting and forging repair method and its application. Background Technology
[0002] High-temperature alloy support plates for aero engines and gas turbines are prone to cracking and ablation under extreme operating conditions, and direct replacement is costly. The industry urgently needs high-performance repair technology, requiring repaired support plates to have high-temperature strength, fatigue resistance, and service life comparable to new products. Traditional repair methods are unable to meet these stringent requirements.
[0003] Current mainstream repair processes have inherent defects: fusion welding technology (such as TIG welding) causes grain coarsening, dissolution of strengthening phases and concentration of residual stress in the heat-affected zone due to excessive heat input; although laser cladding technology has lower heat input, the rapid solidification process easily forms coarse dendritic structures, accompanied by defects such as pores and lack of interlayer fusion, which significantly reduces the mechanical properties of the repaired area.
[0004] Recent advancements in composite repair techniques have failed to fundamentally solve the problem: laser-arc composite methods, due to the high heat input of the arc, cannot avoid microstructural degradation; ultrasonic-assisted methods can only improve the surface quality of the repaired body, with limited effect on stress relief in thick-section components; and reliance on post-treatment processes such as hot isostatic pressing significantly increases process complexity and cost. This field has long faced a triple technical contradiction: the requirement for sufficient thermal fusion in high-density repairs conflicts with the need for low heat input to suppress grain coarsening; fine-grain strengthening requires rapid cooling, while residual stress control requires slow cooling conditions; and achieving performance targets often depends on complex post-treatment, while cost control demands simplified processes. These contradictions severely restrict the high-quality repair of high-temperature alloy supports.
[0005] In view of this, the present invention is proposed. Summary of the Invention
[0006] The purpose of this invention is to provide a laser melting and forging repair method and its application, which aims to improve at least one of the problems mentioned in the background art.
[0007] This invention is implemented as follows: In a first aspect, the present invention provides a laser melting and forging repair method, comprising: Treatment of damaged steel: The damaged area is removed along the direction of crack propagation on the surface of the damaged steel, with a removal depth of a + (1~1.4mm), where a is the depth of the deepest part of the crack. A 60°±5° V-shaped repair bevel is prepared to obtain the steel to be melted and forged. Forging: Laser cladding is applied to the bevel of forged steel. During laser cladding, micro-forging at a frequency of 80-120Hz begins 0.1-0.4 seconds after the solidification line appears at the edge of the molten pool. After the temperature of the single-layer melting and forging drops below 120°C, the next layer of melting and forging is carried out.
[0008] In an optional implementation, the single impact energy of micro-forging is 0.5~2J.
[0009] In an optional implementation, after each single-layer forging is completed, the slag layer is removed, and the forging area is protected with an inert gas curtain until the temperature drops below 120°C.
[0010] In an optional implementation, during the laser cladding process, the laser power P = 800 + k1(d-1), where P is the laser power in W, d is the bevel depth in mm, and k1 is a coefficient with a value of 150 in W / mm. Optionally, the relationship between the toner feeding rate and the scanning speed is v=k2F, where v is the scanning speed, F is the toner feeding rate in g / min, and k2 is a coefficient with a value of 0.6. Optionally, during laser cladding, the spot diameter is 1-5 mm.
[0011] In an optional implementation, the interlayer temperature is monitored in real time. If the temperature is >200°C, the process is paused and an auxiliary cooling air curtain is activated. The next layer is deposited after the temperature drops to ≤120°C.
[0012] In an optional implementation, a fillet with a radius of 0.25 to 0.35 mm is retained at the root of the bevel.
[0013] In an optional implementation, the damaged steel is made of GH3536 nickel-based high-temperature alloy, and the powder material used in the laser cladding process is nickel-based high-temperature alloy powder. Optionally, the chemical composition of the damaged steel is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni; and the chemical composition of the nickel-based high-temperature alloy powder is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni.
[0014] In an optional embodiment, the particle size of the nickel-based superalloy powder is 45~106μm.
[0015] In an optional implementation, the steel to be forged is further subjected to surface cleaning and activation before forging: The cleaning method includes: first ultrasonic cleaning with acetone, then rinsing with ethanol, followed by purging with inert gas; The activation method includes: argon plasma activation treatment of the cleaned steel, wherein the vacuum chamber pressure is (4~6)×10 -2 Pa, plasma power: 400~600W, processing time: 4~6min.
[0016] Secondly, the present invention provides the application of the repair method as described in any of the foregoing embodiments in the repair of high-temperature alloy support plates for aero-engines and gas turbines.
[0017] The present invention has the following beneficial effects: The method provided by this invention, which involves performing high-frequency micro-forging 0.1 to 0.4 seconds after the molten pool solidifies, enables dynamic dendrite fragmentation and heterogeneous nucleation, refines the average grain size of the repaired area, reduces porosity, and completely solves the problems of dendrite coarsening and defect aggregation. In particular, the micro-forging performed at a specific time after solidification alters the flow behavior of the molten pool, causing plastic deformation and grain refinement in the high-temperature solid phase region. Compared to simultaneous laser cladding and micro-forging, this method results in better uniformity and mechanical properties of the cladding layer. Attached Figure Description
[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 Comparison of microhardness of the repaired area with and without micro-forging. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0021] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0022] This invention provides a laser melting and forging repair method, comprising: Treatment of damaged steel: The damaged area is removed along the direction of crack propagation on the surface of the damaged steel, with a removal depth of a + (1~1.4mm), where a is the depth of the deepest part of the crack. A 60°±5° V-shaped repair bevel is prepared to obtain the steel to be melted and forged. Forging: Laser cladding is applied to the bevel of forged steel. During laser cladding, micro-forging at a frequency of 80-120Hz begins 0.1-0.4 seconds after the solidification line appears at the edge of the molten pool. After the temperature of the single-layer melting and forging drops below 120°C, the next layer of melting and forging is carried out.
[0023] The method provided by this invention, which involves performing high-frequency micro-forging 0.1 to 0.4 seconds after the molten pool solidifies, enables dynamic dendrite fragmentation and heterogeneous nucleation, refines the average grain size of the repaired area, reduces porosity, and completely solves the problems of dendrite coarsening and defect aggregation. In particular, the micro-forging performed at a specific time after solidification alters the flow behavior of the molten pool, allowing plastic deformation and grain refinement in the high-temperature solid phase region to occur simultaneously with laser cladding and micro-forging, resulting in better uniformity and mechanical properties of the cladding layer.
[0024] It should be noted that the forging frequency needs to be within the range required by this invention. If the frequency is too low, there will be insufficient heat input, grain coarsening and poor residual stress relief effect. If the frequency is too high, it will cause overheating accumulation, decreased microstructure properties and even microcracks.
[0025] Specifically, the repair method is as follows: S1. Treatment of Damaged Steel Fluorescent penetrant testing was used to determine the crack orientation and depth; The damaged area is removed along the direction of crack propagation on the surface of the damaged steel, with a removal depth of a + (1~1.4mm), where a is the deepest point of the crack. A 60°±5° V-shaped repair bevel is prepared to obtain the steel to be melted and forged.
[0026] Preferably, during the cutting process, a radius of 0.25~0.35mm is retained at the root of the bevel to reduce stress concentration.
[0027] S2, Surface Cleaning and Activation The cleaning process includes: first, ultrasonic cleaning with acetone, then rinsing with ethanol, followed by purging with an inert gas (such as nitrogen).
[0028] Optionally, the ultrasonic frequency can be set to 40kHz and the time to 30min during acetone cleaning. It should be noted that the frequency can also be set higher, in which case the cleaning time can be reduced, and vice versa.
[0029] The activation method includes: argon plasma activation treatment of the cleaned steel, wherein the vacuum chamber pressure is (4~6)×10 -2 Pa, plasma power: 400~600W, processing time: 4~6min.
[0030] Activation can effectively remove residual contaminants on the surface and activate surface atoms, significantly improving the energy and activity of the steel surface, thereby enhancing the adhesion between the coating and the substrate.
[0031] S3, Synchronous Laser Melting and Forging Repair (1) Provide equipment Integrated processing head: coaxial powder feeding nozzle (carrier gas is high-purity argon) + high-frequency laser shock module (shock frequency 50KHz); Real-time monitoring unit: A high-speed camera (10,000 fps) tracks the solidification state of the molten pool; Infrared thermal imager (sampling rate 1kHz) measures the temperature field of the molten pool.
[0032] (2) Melting and forging Laser cladding is applied to the bevel of forged steel. During laser cladding, micro-forging at a frequency of 80-120Hz begins 0.1-0.4 seconds after the solidification line appears at the edge of the molten pool.
[0033] Optionally, the laser power P = 800 + k1(d-1), where P is the laser power in W, d is the depth of the bevel in mm, and k1 is a coefficient with a value of 150 in W / mm. The relationship between the toner feeding rate and the scanning speed is v=k2F, where v is the scanning speed, F is the toner feeding rate in g / min, and k2 is a coefficient with a value of 0.6. During laser cladding, the spot diameter is 1-5mm.
[0034] Laser cladding under the above parameters can ensure good adhesion between the cladding layer and the substrate.
[0035] Optionally, the powder used in the laser cladding process has the same or similar composition as the steel being repaired. This helps to ensure good metallurgical compatibility between the cladding layer and the substrate, reduce differences in chemical composition and thermophysical properties, and thus avoid the generation of defects such as cracks and pores.
[0036] For example, the damaged steel is made of GH3536 nickel-based superalloy, and the powder material used in the laser cladding process is nickel-based superalloy powder.
[0037] Furthermore, the chemical composition of the damaged steel is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni; the chemical composition of the nickel-based high-temperature alloy powder is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni.
[0038] Optionally, the particle size of the nickel-based superalloy powder is 45~106μm. This range of nickel-based superalloy powder ensures good powder flowability and powder feeding stability, while also facilitating the formation of a dense and uniform cladding layer and avoiding inclusions or unmelted particles caused by improper particle size.
[0039] Optionally, the single impact energy of micro-forging is 0.5~2J. Within this energy range, plastic deformation and dynamic recrystallization can be effectively promoted, grains can be refined and internal stress can be eliminated, while avoiding coating deformation or damage caused by excessive energy.
[0040] After each single-layer melting and forging (layer thickness 0.3~0.5mm), use a copper wire brush to remove the surface slag; The argon curtain protects the repair area until the temperature drops below 120°C.
[0041] S4, Interlayer Temperature Control Infrared thermal imagers provide real-time feedback on interlayer temperature; If the temperature is >200℃, pause the process and start the auxiliary cooling gas curtain (argon flow rate 20L / min); continue the next layer deposition after the temperature drops to ≤120℃.
[0042] S5, Post-processing For components requiring high surface finish, diamond grinding wheels are used for precision grinding.
[0043] Example 1 The object to be repaired is a high-temperature alloy support plate for an aircraft engine. The material is GH3536 nickel-based high-temperature alloy, and its chemical composition is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni.
[0044] S1. Fluorescent penetrant testing was used to determine the direction and depth of the crack. The deepest point was found to be 1 mm. The damaged area was removed along the direction of crack propagation on the surface of the damaged steel, with a removal depth of 1 mm. A 62° V-shaped repair bevel (tolerance ±2°) was prepared, and a fillet with a radius of 0.3 mm was retained at the root of the bevel. The surface roughness of the bevel Ra≤3.2μm.
[0045] S2. First, ultrasonic cleaning with acetone at a frequency of 40 kHz for 30 minutes is performed, followed by rinsing with ethanol, and then purging with an inert gas (nitrogen). Afterwards, argon plasma activation treatment is performed, with a vacuum chamber pressure of 5 × 10⁻⁶. -2 Pa, plasma power: 500W, processing time: 6min.
[0046] S3, (1) Provide equipment Integrated processing head: coaxial powder feeding nozzle (carrier gas is high-purity argon) + high-frequency laser shock module (IPG YLS-4000, wavelength 1070nm, fiber optic transmission, shock frequency range of 50KHz), powder flow closed-loop control; Real-time monitoring unit: A high-speed camera (10,000 fps) tracks the solidification state of the molten pool; Infrared thermal imager (sampling rate 1kHz) measures the temperature field of the molten pool.
[0047] (2) Melting and forging Laser cladding is applied to the bevel of forged steel.
[0048] The laser power is 300 W, the scanning speed is 1000 mm / s, and the spot diameter is 2 mm during the laser cladding process.
[0049] The powder material used in the laser cladding process is nickel-based superalloy powder, with a chemical composition of 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni. The particle size of the nickel-based superalloy powder is 45~106μm.
[0050] During the laser cladding process, micro-forging at a frequency of 100Hz begins 0.25 seconds after the solidification line appears at the edge of the molten pool.
[0051] The single impact energy of micro-forging is 1J.
[0052] After each single-layer melting and forging (layer thickness 0.4mm), use a copper wire brush to remove the surface slag; The argon curtain protects the repair area until the temperature drops below 120°C before proceeding to the next layer of melting and forging.
[0053] Example 2 The object to be repaired is the same as in Example 1.
[0054] S1. Cut away the steel along the direction of crack propagation on the surface of the damaged steel to the same depth as in Example 1, and prepare a 55° V-shaped repair bevel (tolerance ±2°). A radius of 0.25 mm is retained at the root of the bevel to reduce stress concentration.
[0055] S2. First, ultrasonic cleaning with acetone at a frequency of 40 kHz for 30 minutes is performed, followed by rinsing with ethanol, and then purging with an inert gas (nitrogen). Afterwards, argon plasma activation treatment is performed, with a vacuum chamber pressure of 4 × 10⁻⁶. -2 Pa, plasma power: 600W, processing time: 4min.
[0056] S3, (1) Provide equipment Same as Example 1.
[0057] (2) Melting and forging Laser cladding is applied to the bevel of forged steel.
[0058] The laser power is 300 W, the scanning speed is 1000 mm / s, and the spot diameter is 2 mm during the laser cladding process.
[0059] The powder material used in the laser cladding process is the same as in Example 1.
[0060] During the laser cladding process, micro-forging at a frequency of 120Hz begins 0.1 seconds after the solidification line appears at the edge of the molten pool.
[0061] The single impact energy of micro-forging is 0.5J.
[0062] After each single-layer melting and forging (layer thickness 0.3mm), use a copper wire brush to remove the surface slag; The argon curtain protects the repair area until the temperature drops below 120°C before proceeding to the next layer of melting and forging.
[0063] Example 3 The object to be repaired is the same as in Example 1.
[0064] S1. Cut away the steel along the direction of crack propagation on the surface of the damaged steel to the same depth as in Example 1, and prepare a 65° V-shaped repair bevel (tolerance ±2°). A radius of 0.35 mm is retained at the root of the bevel to reduce stress concentration.
[0065] S2. First, ultrasonic cleaning with acetone at a frequency of 40 kHz for 30 minutes is performed, followed by rinsing with ethanol, and then purging with an inert gas (nitrogen). Afterwards, argon plasma activation treatment is performed, with a vacuum chamber pressure of 6 × 10⁻⁶. -2 Pa, plasma power: 500W, processing time: 5min.
[0066] S3, (1) Provide equipment Same as Example 1.
[0067] (2) Melting and forging Laser cladding is applied to the bevel of forged steel.
[0068] The laser power is 300 W, the scanning speed is 1000 mm / s, and the spot diameter is 2 mm during the laser cladding process.
[0069] The powder material used in the laser cladding process is the same as in Example 1.
[0070] During the laser cladding process, micro-forging at a frequency of 80 Hz begins 0.4 seconds after the solidification line appears at the edge of the molten pool.
[0071] The single impact energy of micro-forging is 2 J.
[0072] After each single-layer melting and forging (layer thickness 0.5mm), use a copper wire brush to remove the surface slag; The argon curtain protects the repair area until the temperature drops below 120°C before proceeding to the next layer of melting and forging.
[0073] Comparative Example 1 This comparative example is basically the same as Example 1, except that micro-forging begins 0.8 seconds after the solidification line appears at the edge of the molten pool.
[0074] Comparative Example 2 This comparative example is basically the same as Example 1, except that micro-forging and laser cladding are performed simultaneously.
[0075] Comparative Example 3 This comparative example is basically the same as Example 2, except that the frequency of micro-forging is 150Hz.
[0076] Comparative Example 4 This comparative example is basically the same as Example 3, except that the frequency of micro-forging is 50Hz.
[0077] Comparative Example 5 This comparative example is basically the same as Example 1, except that micro-forging is not performed.
[0078] Comparative Example 6 This comparative example uses hot isostatic pressing (HIP) to repair cracks. Specifically, the cracks are held at 1180℃ for 1 hour.
[0079] Experimental Example The performance of the support plates after repair in each embodiment and comparative example was tested, and the performance statistics are shown in Table 1 or... Figure 1 .
[0080] The performance items tested include microhardness, grain size and tensile strength. The test methods are based on GB / T 4340.1-2009 "Metallic materials - Vickers hardness test - Part 1: Test method" and GB / T 228.1-2021 "Metallic materials - Tensile test - Part 1: Test method at room temperature".
[0081] Table 1 Performance data for each embodiment and comparative example
[0082] Through Table 1 and Figure 2 ( Figure 1 (See the comparison diagram of the microhardness of the repaired area with and without microforging). It can be seen that the repair methods provided by the various embodiments of the present invention have better microhardness at the repair site compared with the method without microforging (Comparative Example 5), and the columnar crystals in the cladding area are transformed into equiaxed crystals, which have better isotropy.
[0083] As can be seen from Table 1, the repair methods provided in the various embodiments of the present invention have better microhardness, smaller grain size and higher bonding strength compared with the hot isostatic pressing process repair (Comparative Example 6).
[0084] Comparing Comparative Example 1 with Example 1, the bonding strength at the repair site in Comparative Example 1 is significantly worse than that in Example 1, indicating that forging too late after the solidification line appears will result in a weaker bonding force. Comparing Comparative Example 2 with Example 1, the bonding strength of the repaired area in Comparative Example 2 is significantly worse than that in Example 1, indicating that forging within a specific time range after the solidification line appears can improve the interfacial bonding performance of the repaired area more than simultaneous cladding and forging. Comparing Comparative Example 3 with Example 2, the bonding strength at the repair site in Comparative Example 3 was significantly worse than that in Example 2, indicating that excessively high forging frequency will reduce the interfacial bonding performance. Comparing Comparative Example 4 with Example 3, the bonding strength at the repair site in Comparative Example 4 was significantly worse than that in Example 3, indicating that a low forging frequency would reduce the interfacial bonding performance.
[0085] In summary, the method provided by this invention, by performing high-frequency micro-forging 0.1 to 0.4 seconds after the molten pool solidifies, can achieve dynamic dendrite fragmentation and heterogeneous nucleation, refine the average grain size of the repair zone, reduce porosity, and completely solve the problems of dendrite coarsening and defect aggregation. In particular, the micro-forging performed at a specific time after solidification alters the flow behavior of the molten pool, causing plastic deformation and grain refinement in the high-temperature solid phase region. Compared to simultaneous laser cladding and micro-forging, this method results in better uniformity and mechanical properties of the cladding layer. This method effectively solves the technical challenges of weak interfacial bonding and poor fatigue resistance in aerospace high-temperature alloy additive components.
[0086] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A laser melting and forging repair method, characterized in that, include: Treatment of damaged steel: The damaged area is removed along the direction of crack propagation on the surface of the damaged steel, with a removal depth of a + (1~1.4mm), where a is the depth of the deepest part of the crack. A 60°±5° V-shaped repair bevel is prepared to obtain the steel to be melted and forged. Forging: Laser cladding is applied to the bevel of the steel to be melted and forged; During laser cladding, micro-forging at a frequency of 80-120Hz begins 0.1-0.4 seconds after the solidification line appears at the edge of the molten pool. After the temperature of the single-layer melting and forging drops below 120°C, the next layer of melting and forging is carried out.
2. The repair method according to claim 1, characterized in that, The single impact energy of micro-forging is 0.5~2J.
3. The repair method according to claim 1, characterized in that, After each layer of forging is completed, the slag in that layer is removed, and the forging area is protected with an inert gas curtain until the temperature drops below 120°C.
4. The repair method according to claim 1, characterized in that, During the laser cladding process, the laser power P = 800 + k1(d-1), where P is the laser power in W, d is the depth of the bevel in mm, and k1 is a coefficient with a value of 150 in W / mm. Optionally, the relationship between the toner feeding rate and the scanning speed is v=k2F, where v is the scanning speed, F is the toner feeding rate in g / min, and k2 is a coefficient with a value of 0.
6. Optionally, during laser cladding, the spot diameter is 1-5 mm.
5. The repair method according to claim 1, characterized in that, The interlayer temperature is monitored in real time. If the temperature is >200℃, the process is paused and the auxiliary inert gas curtain is activated. The next layer is deposited after the temperature drops to ≤120℃.
6. The repair method according to claim 1, characterized in that, The root of the bevel retains a rounded corner with a radius of 0.25~0.35mm.
7. The repair method according to claim 1, characterized in that, The damaged steel is made of GH3536 nickel-based high-temperature alloy, and the powder material used in the laser cladding process is nickel-based high-temperature alloy powder. Optionally, the chemical composition of the damaged steel is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni; and the chemical composition of the nickel-based high-temperature alloy powder is 21.16Cr-18.86Fe-9.78Mo-2.20Co-0.62W-0.07C-0.04Si-bal.Ni.
8. The repair method according to claim 7, characterized in that, The particle size of the nickel-based high-temperature alloy powder is 45~106μm.
9. The repair method according to claim 1, characterized in that, Prior to melting and forging, the process also includes surface cleaning and activation of the steel to be melted and forged. The cleaning method includes: first ultrasonic cleaning with acetone, then rinsing with ethanol, followed by purging with inert gas; The activation method includes: argon plasma activation treatment of the cleaned steel, wherein the vacuum chamber pressure is (4~6)×10 -2 Pa, plasma power: 400~600W, processing time: 4~6min.
10. The application of the repair method as described in any one of claims 1 to 9 in the repair of high-temperature alloy support plates for aero-engines and gas turbines.