High Al / Ti content nickel-based superalloy laser melting deposition repair cracking inhibition method and device

Abstract

The invention belongs to the field of metal material laser repair, and discloses a high Al / Ti content nickel-based superalloy laser melting deposition repair cracking inhibition method and device, a double-molten-pool laser melting deposition repair method is used, two molten pools coincide in a certain ratio, the laser power corresponding to each molten pool changes in real time in a short time, and the laser power of the two molten pools changes in real time. And it is guaranteed that the energy input of lasers in the two molten pools at each moment is different, convection between the molten pools is forcibly caused, segregation of the scales of the molten pools is restrained, the cracking tendency is reduced, and the repairing efficiency is improved. And the cracking phenomenon in the laser melting deposition repairing process of the nickel-based high-temperature alloy with the high Al / Ti content is inhibited while powder components are not changed and the repairing efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the field of laser repair of metal materials, and specifically relates to a method and device for inhibiting cracking during laser melting deposition repair of nickel-based high-temperature alloys with high Al / Ti content. Background Art

[0002] Nickel-based superalloys are currently irreplaceable key structural materials for high-temperature parts of military and civil aviation engines and gas turbines, especially turbine blades, guide vanes, turbine discs and combustion chambers in the core of aviation engines. Judging from the current development status, nickel-based superalloys will continue to be the main materials for important parts of aviation engines and gas turbines for a long time in the future. However, nickel-based superalloys composed of a large number of high-value elements are more expensive than other commonly used metals. Once the components are damaged during service, the cost of replacing the entire component is too high. Therefore, local repair using laser melting deposition technology is a maintenance method that significantly reduces costs. The key high-value parts of aviation engines are mainly nickel-based superalloys with high Al / Ti content. Generally, alloy powders with basically the same composition are used for repair during laser melting deposition repair. Under the heating action of the laser melting deposition repair process, nickel-based superalloys with high Al / Ti content are prone to eutectic reaction with the matrix, resulting in the formation of grain boundary liquid film. At the same time, the stress change during the repair process causes the liquid film to tear and the sample to crack. Therefore, it is of great engineering significance to inhibit the cracking of nickel-based superalloys with high Al / Ti content during laser melting deposition repair.

[0003] Methods for crack control in laser melting deposition of nickel-based high-temperature alloys with high Al / Ti content usually include adjusting alloy composition, preheating substrate, applying mechanical vibration, controlling convection with external magnetic field, etc. The above methods have certain effects on suppressing cracking. On the basis of not changing the original composition of the alloy, the external mechanical vibration and magnetic field control in the laser melting deposition process suppress solute segregation by microscopic disturbance of the molten pool, thereby suppressing cracking. These crack control effects based on the external field have considerable fluctuations with the change of equipment power and the movement of the molten pool. In view of the above shortcomings, this patent proposes a method and device for suppressing cracking in the laser melting deposition repair process of nickel-based high-temperature alloys with high Al / Ti content. Using the double-molten pool laser melting deposition repair method, there is a certain ratio of overlap between the two molten pools, and the laser power corresponding to each molten pool changes in real time in a short time, ensuring that the energy input of the laser received by the two molten pools at each moment is different, thereby forcing convection between the molten pools, suppressing the segregation of the molten pool scale, and thus reducing the cracking tendency. The cracking phenomenon during the laser melting deposition repair process of nickel-based high-temperature alloys with high Al / Ti content can be suppressed without changing the powder composition and improving the repair efficiency. Summary of the invention

[0004] The purpose of the present invention is to suppress cracking during the laser melting deposition repair process of a nickel-based high-temperature alloy with a high Al / Ti content without changing the alloy composition and improving the repair efficiency.

[0005] In order to achieve the purpose and other advantages according to the present invention, a method and device for suppressing cracking in a laser melting deposition repair process of a nickel-based high-temperature alloy with a high Al / Ti content is provided, comprising the following steps:

[0006] Step 1: Use a coaxial laser cladding head supported by a semiconductor laser as the main repair equipment. The nickel-based high-temperature alloy with a high Al / Ti content is characterized by a total mass percentage of Al and Ti elements between 5% and 15%. The composition of the material to be repaired is consistent with that of the powder material for laser cladding.

[0007] Step 2: Grind and clean the surface of the material to be repaired in step 1 to remove residual pollutants or foreign non-matrix materials on the surface to ensure that there is no oil stain or foreign matter attached to the surface.

[0008] Step 3: For the laser cladding equipment in step 1, the maximum power of the laser is 8KW, the scanning speed during the laser melting deposition repair process is 200-400mm / min, and the size of the laser focus spot is 2mm. During the laser melting deposition repair process, high-purity argon (purity ≥ 99.99%) atmosphere protection is used.

[0009] Step 4: Further, two laser cladding heads are configured, whose models, dimensions, sizes and key parameters are consistent, and the arrangement direction of the two laser cladding heads is perpendicular to the laser scanning direction.

[0010] Step 5: The two laser cladding heads use the same powder feeding material and keep the same powder feeding speed, which is 10-15 g / min. The powder has good sphericity and the particle size distribution range is 70-150 μm.

[0011] Step 6: The spot distance between the dual laser cladding equipment is achieved through precise adjustment. To ensure that the two molten pools are partially connected, the dynamic overlap rate range of the dual molten pools is 20% ≥ 40%.

[0012] Step 7: Strengthen the convection of liquid metal by connecting and interfering the two laser molten pools. The convection of the molten pools is achieved by: generating flow disturbances in the overlapping area of ​​the two molten pools to reduce solute segregation. Adjust the energy input of the dual laser heads to enhance the flow field difference.

[0013] Step 8: The energy distribution of the double molten pools needs to maintain dynamic differentiation. The power waveform of each laser cladding head is set to change alternately to ensure that when the power of one side is high, the power of the other side is low, forming an asymmetric flow and optimizing the solute distribution inside the molten pool.

[0014] Step 9: To achieve the goal of step 8, the laser power and laser waveform of the two laser cladding processes can be adjusted independently. Pulsed lasers are used, and the power waveforms are kept in an alternating mode, characterized in that when the laser input power of one molten pool is high, the laser input power of the other molten pool is low, so as to enhance the flow field disturbance and optimize the solute uniformity.

[0015] Step 10. The control parameters of the pulse laser are mainly characterized by pulse period, duty cycle, peak power, and pulse shape. The pulse period is in milliseconds, the duty cycle is 50%, and the pulse shape includes but is not limited to square wave, rectangular wave, sine wave, etc.

[0016] Step 11, as attached Figure 2 As shown in FIG. 1 , the pulse period, duty cycle, peak power, and pulse shape of the pulse lasers of the two laser cladding heads are exactly the same, but their phases are complementary, the waveforms match each other, and the total power of the two molten pools at any time always remains unchanged.

[0017] Step 12: The connection of the two molten pools requires that the light spots of the two laser cladding heads are extremely close or even partially overlapped. Due to the size limitation of the laser cladding head, when the central axis of the laser cladding head is perpendicular to the plane to be repaired, the size limitation of the laser cladding head itself makes it impossible for the two light spots to be sufficiently close to form a double molten pool connected to each other. Therefore, the two laser cladding heads need to be tilted at a certain angle respectively so that the central axis of the laser cladding head is relative to a point.

[0018] Step 13: The mechanical connection feature of the two laser cladding heads is that, in addition to the independent adjustment of the tilting angles, the movements during the laser melting deposition repair process are all consistent. In order to ensure that the movements of the two laser cladding heads are consistent, the movements of the two laser cladding heads are synchronized by an integrated mechanical drive device, or two independent drive devices can be used to coordinate and control the synchronous movement.

[0019] Step 14: Further, the tilting angle of the laser cladding head is 5-10°, and the tilting angles of the two laser cladding heads are consistent.

[0020] Step 15: Use a dual laser cladding head to repair the damaged part according to the shape of the part to be repaired. Except for generating a dual molten pool and matching the laser cladding parameters required for the dual molten pool, the rest of the repair process is consistent with the traditional laser melting deposition repair.

[0021] Compared with the traditional technology, the present invention has the following technical features:

[0022] 1. The heat convection in the traditional single molten pool is relatively weak, and the distribution of solute elements is prone to segregation, forming a low-melting-point eutectic phase that leads to the formation of solidification cracks. Compared with the traditional single molten pool cladding, the partially overlapping area of ​​the double molten pool forms a more complex flow pattern and enhances the convection effect. The enhanced convection and disturbance can effectively reduce the solute segregation in the molten pool and homogenize the distribution of chemical components, thereby reducing the formation of eutectic phases caused by solute segregation and reducing the cracking tendency of the laser repair process of nickel-based high-temperature alloys with high Al / Ti content.

[0023] 2. Compared with single-molten-pool laser cladding, dual-laser dual-molten-pool repair can cover a larger area and improve repair efficiency. And by flexibly controlling the laser head power and the molten-pool overlap ratio, repeated cladding can be avoided, further improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Attached Figure 1 It is a schematic diagram of a double-molten-pool laser cladding device provided by a specific embodiment of the present invention;

[0025] Attached Figure 2 is the pulse power waveform of two laser cladding heads in a specific embodiment of the present invention; DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments.

[0027] Step 1: Use a coaxial laser cladding head supported by a semiconductor laser as the main repair equipment. The nickel-based high-temperature alloy with high Al / Ti content is characterized by a total mass percentage of Al and Ti elements between 5% and 15%. The powder material used for laser cladding has the same composition as the material to be repaired. Figure 1 The commercial grade of the substrate to be repaired is Inconel 738, and its composition by mass percentage is: Co: 8.5%, Cr: 16%, Mo: 1.75%, W: 2.6%, Nb: 0.9%, C: 0.11, Al: 3.4%, Ti: 3.4%, Ni: balance.

[0028] Step 2: polish and clean the surface of the substrate to be repaired in step 1 to remove residual pollutants or foreign non-matrix materials on the surface to ensure that there is no oil stain or foreign matter attached to the surface.

[0029] Step 3: For the laser cladding equipment in step 1, the maximum power of the laser is 8KW, the scanning speed during the laser melting deposition repair process is 230mm / min, and the size of the laser focus spot is 2mm. During the laser melting deposition repair process, high-purity argon (purity ≥ 99.99%) atmosphere protection is used.

[0030] Step 4: Further, two laser cladding heads are configured, whose models, dimensions, sizes and key parameters are consistent, and the arrangement direction of the two laser cladding heads is perpendicular to the laser scanning direction.

[0031] Step 5: The two laser cladding heads use the same powder feeding material and the powder feeding speed is kept the same, which is 12g / min. The powder has good sphericity and the particle size distribution range is 70-150μm.

[0032] Step 6: The spot distance between the dual laser cladding equipment is achieved through precise adjustment. To ensure that the two molten pools are partially connected, the dynamic overlap rate range of the dual molten pools is 30%.

[0033] Step 7: Strengthen the convection of liquid metal by connecting and interfering the two laser molten pools. The convection of the molten pools is achieved by: generating flow disturbances in the overlapping area of ​​the two molten pools to reduce solute segregation. Adjust the energy input of the dual laser heads to enhance the flow field difference.

[0034] Step 8: The energy distribution of the double molten pools needs to maintain dynamic differentiation. The power waveform of each laser cladding head is set to change alternately to ensure that when the power of one side is high, the power of the other side is low, forming an asymmetric flow and optimizing the solute distribution inside the molten pool.

[0035] Step 9: To achieve the goal of step 8, the laser power and laser waveform of the two laser cladding processes can be adjusted independently. Pulsed lasers are used, and the power waveforms are kept in an alternating mode, characterized in that when the laser input power of one molten pool is high, the laser input power of the other molten pool is low, so as to enhance the flow field disturbance and optimize the solute uniformity.

[0036] Step 10: The control parameters of the pulse laser are mainly characterized by pulse period, duty cycle, peak power, and pulse shape. The pulse period is in the millisecond level, the duty cycle is 50%, and in this embodiment, the pulse waveform is a rectangular wave, as shown in the attached figure. Figure 2 As shown in the figure, the peak-to-valley power of laser cladding head A is 1.5 KW, and the peak-to-bottom power is 0 KW; the peak-to-valley power and peak-to-bottom power of laser cladding head B are the same as those of laser cladding head A.

[0037] Step 11, as attached Figure 2 As shown in the figure, the pulse period, duty cycle, peak power, and pulse shape of the pulse lasers of the two laser cladding heads are exactly the same. However, their phases are complementary and their waveforms match each other, that is, the total power P of the two molten pools at any time A +P B The waveform complementarity is reflected in the attached Figure 2 In the period from T0 to T0+n, the power output of the laser cladding head A is at a peak during the period from T0 to T0+1, while the power output of the laser cladding head B is at a trough.

[0038] Step 12: The connection of the two molten pools requires that the light spots of the two laser cladding heads are extremely close or even partially overlapped. Due to the size limitation of the laser cladding head, when the central axis of the laser cladding head is perpendicular to the plane to be repaired, the size limitation of the laser cladding head itself makes it impossible for the two light spots to be sufficiently close to form a double molten pool connected to each other. Therefore, the two laser cladding heads need to be tilted at a certain angle respectively so that the central axis of the laser cladding head is relative to a point.

[0039] Step 13, the mechanical connection feature of the two laser cladding heads is that, in addition to the independent adjustment of the tilting angles of each, the movements during the laser melting deposition repair process are all consistent. In order to ensure that the movements of the two laser cladding heads are consistent, the movements of the two laser cladding heads are synchronized through an integrated mechanical drive device, or two independent drive devices can be used to coordinate and control the synchronous movement. In the embodiment, an integrated mechanical drive device is used to achieve synchronization.

[0040] Step 14: Further, the tilting angle of the laser cladding head is 8°, and the tilting angles of the two laser cladding heads are consistent. The laser cladding head is tilted toward the molten pool.

[0041] Step 15: Use a dual laser cladding head to repair the damaged part according to the shape of the part to be repaired. In addition to generating a dual molten pool and matching the laser cladding parameters required for the dual molten pool, the rest of the repair process is consistent with the traditional laser melting deposition repair. This embodiment uses a single laser cladding verification.

Claims

1. A method and device for laser melting deposition repair cracking inhibition of high Al / Ti content nickel-based high-temperature alloy, characterized in that: Using the double-molten-pool laser melting deposition repair method, there is a certain ratio of overlap between the two molten pools. The laser power corresponding to each molten pool changes in real time within a short period of time, ensuring that the energy input of the laser into the two molten pools is different at each moment, forcing convection between the molten pools, inhibiting the segregation of the molten pool scale, and thus reducing the tendency to crack.

2. A method and device for suppressing cracking during laser melting deposition repair of a nickel-based high-temperature alloy with a high Al / Ti content according to claim 1. Characterized in that: The specific steps include: Step 1: Use a coaxial laser cladding head supported by a semiconductor laser as the main repair equipment. The nickel-based high-temperature alloy with a high Al / Ti content is characterized by a total mass percentage of Al and Ti elements between 5% and 15%. The composition of the material to be repaired and the powder material for laser cladding is consistent. Step 2: Grind and clean the surface of the material to be repaired in step 1 to remove residual pollutants or foreign non-matrix materials on the surface to ensure that there is no oil stain and foreign matter attached to the surface; Step 3: For the laser cladding equipment in step 1, the maximum power of the laser is 8KW, the scanning speed during the laser melting deposition repair process is 200-400mm / min, and the size of the laser focus spot is 2mm. During the laser melting deposition repair process, high-purity argon (purity ≥ 99.99%) atmosphere protection is used; Step 4: Further, two laser cladding heads are configured, whose models, dimensions, sizes and key parameters are consistent, and the arrangement direction of the two laser cladding heads is perpendicular to the laser scanning direction; Step 5: The two laser cladding heads use the same powder feeding material and keep the same powder feeding speed, which is 10-15 g / min. The powder has good sphericity and the particle size distribution range is 70-150 μm. Step 6: The spot distance between the dual laser cladding equipment is achieved through precise adjustment. To ensure that the two molten pools are partially connected, the dynamic overlap rate of the dual molten pools ranges from 20% to 40%; Step 7: Strengthen the convection of liquid metal by connecting and interfering the two laser molten pools. The convection of the molten pools is achieved by: generating flow disturbances in the overlapping area of ​​the two molten pools to reduce solute segregation, and adjusting the energy input of the two laser heads to enhance the flow field difference; Step 8: The energy distribution of the double molten pools needs to maintain dynamic differentiation. The power waveform of each laser cladding head is set to change alternately to ensure that when the power of one side is high, the power of the other side is low, forming an asymmetric flow and optimizing the solute distribution inside the molten pool.

3. According to step eight of claim 2, in order to achieve its object, it is characterized in that: Step 9: To achieve the goal of step 8, the laser power and laser waveform of the two laser cladding processes can be adjusted independently. Pulsed laser is used, and the power waveform is kept in an alternating change mode, characterized in that when the laser input power of one molten pool is high, the laser input power of the other molten pool is low, so as to enhance the flow field disturbance and optimize the solute uniformity; Step 10, the control parameters of the pulse laser are mainly characterized by pulse period, duty cycle, peak power, and pulse shape, wherein the pulse period is in milliseconds, the duty cycle is 50%, and the pulse shape includes but is not limited to square wave, rectangular wave, sine wave, etc.; Step 11: The pulse period, duty cycle, peak power, and pulse shape of the pulse lasers of the two laser cladding heads are completely consistent, but their phases are complementary, the waveforms match each other, and the total power of the two molten pools at any time always remains unchanged; Step 12: The connection of the double molten pools requires that the light spots of the two laser cladding heads are extremely close or even partially overlapped. Due to the size limitation of the laser cladding head, when the central axis of the laser cladding head is perpendicular to the plane to be repaired, the size limitation of the laser cladding head itself makes it impossible for the two light spots to be sufficiently close to form a double molten pool connected to each other. Therefore, the two laser cladding heads need to be tilted at a certain angle respectively so that the central axis of the laser cladding head is relative to a point. Step 13: The mechanical connection feature of the two laser cladding heads is that, in addition to the independent adjustment of the tilting angles of each head, the movements during the laser melting deposition repair process are all kept consistent. In order to ensure that the movements of the two laser cladding heads are kept consistent, the movements of the two laser cladding heads are synchronized by an integrated mechanical drive device, or two independent drive devices can be used to coordinate and control the synchronous movement. Step 14: Further, the tilting angle of the laser cladding head is 5-10°, and the tilting angles of the two laser cladding heads are consistent.

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