In-situ heat treatment method and device for laser additive manufacturing of nickel-based superalloy

Abstract

The present application belongs to the technical field of additive manufacturing, and particularly relates to an in-situ heat treatment method and device for laser additive manufacturing of nickel-based superalloy. The present application uses laser additive manufacturing technology to prepare nickel-based superalloy. In the process of laser additive manufacturing, the heat treatment temperature in the heat affected zone is tracked in real time, the magnetic field is controlled to act on the heat affected zone of the nickel-based superalloy, and in-situ heat treatment is performed by using the residual heat of the heat affected zone, without the need to separately introduce other heating sources. The present application introduces a transverse static magnetic field or a transverse alternating magnetic field for in-situ heat treatment, so as to regulate and control the microstructure, element distribution and precipitate size of the nickel-based superalloy, reduce composition segregation and residual stress, and avoid the generation of cracks in the nickel-based superalloy.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to an in-situ heat treatment method and apparatus for laser additive manufacturing of nickel-based high-temperature alloys. Background Technology

[0002] Nickel-based superalloys are widely used in aerospace and gas turbine fields due to their excellent high-temperature mechanical properties. Compared with nickel-based superalloys, iron-based alloys have limited temperature resistance, and cobalt is relatively scarce in cobalt-based alloys. Nickel-based superalloys, on the other hand, have good fatigue resistance, creep resistance, and oxidation resistance above 600℃, and are less expensive than cobalt-based alloys, making them the most widely used.

[0003] The emergence of laser additive manufacturing technology has provided new ideas for the design and manufacture of complex nickel-based superalloy parts. Additive manufacturing is a technology that slices a 3D solid model and uses a high-energy beam to melt alloy powder or wire to manufacture layer by layer. It eliminates the dependence on molds in traditional processes, shortens the production cycle, and enables customized production.

[0004] The complex thermal cycling during additive manufacturing of nickel-based superalloys leads to problems such as cracking, stress deformation, precipitation, and coarse microstructure during solidification, severely hindering the development of nickel-based superalloy additive manufacturing. Nickel-based superalloys have complex compositions and high melting points. Traditional heat treatment methods involve holding the resulting nickel-based superalloy part at high temperature under vacuum after printing. However, this method is ineffective in controlling microstructure growth and compositional segregation, resulting in a high susceptibility to cracking. Summary of the Invention

[0005] The purpose of this invention is to provide an in-situ heat treatment method and apparatus for laser additive manufacturing of nickel-based superalloys. The in-situ heat treatment method provided by this invention can make the nickel-based superalloys obtained by laser additive manufacturing have uniform composition and no cracks.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides an in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys, comprising the following steps:

[0008] Nickel-based superalloy powder is subjected to laser additive manufacturing, and the residual heat from laser additive manufacturing is used to perform in-situ heat treatment on the deposited layer; the in-situ heat treatment is performed under magnetic field conditions.

[0009] The temperature of the region where the magnetic field acts is not lower than the γ' phase dissolution temperature of the nickel-based superalloy and not higher than the solidus temperature.

[0010] Preferably, the duration of the magnetic field is the time during which the temperature of the deposited layer of the nickel-based superalloy remains between the γ' phase dissolution temperature and the solidus temperature.

[0011] Preferably, the magnetic field is a transverse static magnetic field or an alternating magnetic field; the strength of the magnetic field is not higher than 1T.

[0012] Preferably, the laser power of the laser additive manufacturing is 1200-2000W.

[0013] Preferably, the temperature of the area affected by the magnetic field is 600–1350°C, and the duration of the magnetic field's effect does not exceed 5 minutes.

[0014] Preferably, the nickel-based superalloy is a precipitation-strengthened nickel-based superalloy; the precipitation-strengthened nickel-based superalloy is a nickel-based polycrystalline alloy or a nickel-based single-crystal alloy.

[0015] Preferably, the magnetic field moves within the deposited layer; the temperature of the area affected by the magnetic field is synchronously tracked by an infrared thermal imaging detector.

[0016] Preferably, the substrate used in the laser additive manufacturing comprises a nickel-based high-temperature alloy substrate or a stainless steel substrate; the preheating temperature of the substrate is 200–1150°C.

[0017] Preferably, the flowability of the nickel-based high-temperature alloy powder is not higher than 30s / 50g, and the particle size is 50-150μm.

[0018] This invention also provides an in-situ heat treatment apparatus for laser additive manufacturing of nickel-based superalloys, comprising a mechanical control system and a magnetic field control system:

[0019] The mechanical control system includes a base 4;

[0020] Robotic arm 5; the robotic arm 5 and the base 4 are movably connected;

[0021] Motor 6; the motor 6 is used to provide power to the robotic arm 5;

[0022] Motor mounting platform 7; the motor 6 is mounted on the mechanical control system of the motor mounting platform 7;

[0023] The magnetic field control system includes a mounting assembly 1; the mounting assembly 1 is U-shaped; the mounting assembly 1 is connected to the motor mounting platform 7;

[0024] Magnetic field component 2; the magnetic field component 2 is disposed within the U-shaped groove of the mounting component 1;

[0025] Infrared thermal imaging detector 8; the infrared thermal imaging detector 8 is disposed at the axisymmetric center of the mounting assembly 1;

[0026] 9. Laser source.

[0027] This invention provides an in-situ heat treatment method for nickel-based superalloys manufactured using laser additive manufacturing. The invention utilizes laser additive manufacturing technology to prepare nickel-based superalloys. A magnetic field is applied to the heat-affected zone (the area already printed during laser additive manufacturing and still affected by heat transfer) of the nickel-based superalloy. The residual heat from the heat-affected zone is used for in-situ heat treatment, eliminating the need for additional heating sources. By introducing a transverse static magnetic field or a transverse alternating magnetic field for in-situ heat treatment, the microstructure, elemental distribution, and precipitate size of the nickel-based superalloy can be better controlled, reducing component segregation and residual stress, preventing crack formation, and expanding the application fields of nickel-based superalloys.

[0028] Furthermore, in the laser additive manufacturing process, the present invention controls the magnetic field to move synchronously with the nickel-based superalloy obtained by laser additive manufacturing, and the temperature of the area affected by the magnetic field is synchronously tracked by an infrared thermal imaging detector, which can more accurately control the temperature of the area affected by the magnetic field and better avoid the generation of cracks in the nickel-based superalloy.

[0029] This invention also provides an in-situ heat treatment apparatus for laser additive manufacturing of nickel-based superalloys. The apparatus provided by this invention is low in cost, easy to operate, and has good economic and social benefits. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The diagram shows the structure of the in-situ heat treatment device for laser additive manufacturing of nickel-based superalloys provided by the present invention; wherein, 1 is the mounting component, 2 is the magnetic field component, 3 is the worktable, 4 is the base, 5 is the robotic arm, 6 is the motor, 7 is the motor mounting platform, 8 is the infrared thermal imaging detector, and 9 is the laser source.

[0032] Figure 2 A flowchart of the in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys provided by the present invention;

[0033] Figure 3 The image shows the microstructure of GH4099 prepared in Example 1 of this invention.

[0034] Figure 4 This is a microstructure diagram of the nickel-based single-crystal superalloy DD5 prepared in Example 2 of the present invention. Detailed Implementation

[0035] This invention provides an in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys, comprising the following steps:

[0036] Nickel-based superalloy powder is subjected to laser additive manufacturing, and the residual heat from laser additive manufacturing is used to perform in-situ heat treatment on the deposited layer; the in-situ heat treatment is performed under magnetic field conditions.

[0037] The temperature of the region where the magnetic field acts is not lower than the γ' phase dissolution temperature of the nickel-based superalloy and not higher than the solidus temperature.

[0038] In this invention, the nickel-based superalloy powder is preferably dried before laser additive manufacturing; the flowability of the dried nickel-based superalloy powder is preferably not higher than 30s / 50g, more preferably not higher than 20s / 50g, and even more preferably not higher than 18s / 50g; the dried nickel-based superalloy powder is preferably stored in a protective gas for later use; the protective gas is preferably nitrogen; the particle size of the nickel-based superalloy powder is preferably 50-150μm, more preferably 70-120μm, and even more preferably 90-110μm; the nickel-based superalloy is preferably a precipitation-strengthened nickel-based superalloy; the precipitation-strengthened nickel-based superalloy is preferably a nickel-based polycrystalline alloy or a nickel-based single-crystal alloy; the nickel-based polycrystalline alloy preferably includes superalloy GH4099, superalloy IN792, or superalloy IN738; the nickel-based single-crystal alloy preferably includes superalloy IN792, superalloy DD5, single-crystal superalloy CMSX-4, or single-crystal superalloy CMSX-10.

[0039] In this invention, the γ' phase dissolution temperature and solidus temperature of the nickel-based superalloy are preferably obtained by the following method: thermal analysis of the nickel-based superalloy to obtain the γ' phase dissolution temperature and solidus temperature; the thermal analysis method is preferably differential scanning calorimetry (DSC); this invention determines the γ' phase dissolution temperature and solidus temperature of the nickel-based superalloy by measuring the DSC curve using differential scanning calorimetry.

[0040] In this invention, the equipment for laser additive manufacturing is preferably a laser-directed energy deposition 3D printing device, more preferably a laser additive manufacturing (LAM) device; the temperature of the powder bed used in laser additive manufacturing is preferably 20-30°C, more preferably 20-25°C; the method of laser additive manufacturing is preferably ring-shaped powder feeding; the powder feeding speed of the ring-shaped powder feeding is preferably 4-10 g / min, more preferably 4.5-9.5 g / min; the laser power of laser additive manufacturing is preferably 1200-2000 W, more preferably 1400-1800 W, and even more preferably 1600 W; the scanning speed of laser additive manufacturing is preferably 400-700 mm / min, more preferably... The laser additive manufacturing process is characterized by a speed of 420–600 mm / min. The substrate used in the laser additive manufacturing is preferably a nickel-based high-temperature alloy substrate or a stainless steel substrate. The nickel-based high-temperature alloy substrate is preferably a Hastelloy substrate. The preheating temperature of the substrate is preferably 200–1150°C, more preferably 400–950°C, and even more preferably 600–850°C. The substrate is preferably water-cooled or preheated before laser additive manufacturing until the target temperature is reached. The magnetic field preferably moves within the deposited layer. The movement of the magnetic field within the deposited layer is preferably such that when the temperature of the deposited layer is lower than the magnetic field's operating temperature range, the magnetic field's movement speed matches the printing speed of the laser additive manufacturing, and the magnetic field always moves below the printing layer. The temperature of the magnetic field's operating area is preferably tracked synchronously using an infrared thermal imaging detector.

[0041] In this invention, the duration of the magnetic field is preferably the time during which the temperature of the deposited layer of the nickel-based superalloy remains between the γ' phase dissolution temperature and the solidus temperature, more preferably not exceeding 5 minutes, and even more preferably 0.1 to 3 minutes; the temperature of the magnetic field's operating region is preferably 600 to 1350°C, more preferably 1100 to 1350°C, and even more preferably 1150 to 1350°C; this invention utilizes the residual heat from laser additive manufacturing to perform in-situ heat treatment on the deposited layer, that is, in-situ heat treatment is performed at the annealing temperature (below the solidus temperature).

[0042] In this invention, the magnetic field is preferably a transverse static magnetic field or an alternating magnetic field; the strength of the magnetic field is preferably not higher than 1T; the strength of the magnetic field is preferably measured using a Tesla meter before laser additive manufacturing; the slicing and layering are preferably performed using 3D CAD modeling software before laser additive manufacturing, and the obtained slicing and layering data is imported into the preprocessing system of the laser additive manufacturing equipment; during the laser additive manufacturing process, 3D printing is preferably performed according to the slicing and layering data, and the magnetic field is moved to a position that matches the temperature range of the magnetic field during printing by pre-setting the temperature range of the magnetic field, and the deposited layer is subjected to in-situ heat treatment. This invention addresses the high susceptibility to hot cracking, fine microstructure, and compositional segregation of nickel-based superalloys manufactured by laser additive manufacturing. It utilizes a magnetic field to perform in-situ heat treatment on nickel-based superalloys, precisely positioning the heat treatment location in real time, and applying a transverse stable magnetic field to assist in heat treatment, thereby reducing thermal stress, controlling the size of the precipitated phase, and reducing compositional segregation.

[0043] After laser additive manufacturing is completed, the appearance and microstructure of the nickel-based superalloy molded part are preferably tested. Based on the obtained appearance and microstructure of the nickel-based superalloy, the in-situ heat treatment parameters of the nickel-based superalloy manufactured by laser additive manufacturing are optimized. Specifically, when solid cracks occur in the nickel-based superalloy, the magnetic field strength is increased and the magnetic field duration is extended; when the microstructure of the nickel-based superalloy is still not uniform, the magnetic field strength is increased, the temperature range of the magnetic field is expanded, and the magnetic field duration is extended. The appearance and microstructure of the nickel-based superalloy molded part are preferably tested using an optical microscope and a scanning electron microscope.

[0044] This invention also provides an in-situ heat treatment apparatus for laser additive manufacturing of nickel-based superalloys, comprising a mechanical control system and a magnetic field control system:

[0045] The mechanical control system includes a base 4;

[0046] Robotic arm 5; the robotic arm 5 and the base 4 are movably connected;

[0047] Motor 6; the motor 6 is used to provide power to the robotic arm 5;

[0048] Motor mounting platform 7; the motor 6 is mounted on the mechanical control system of the motor mounting platform 7;

[0049] The magnetic field control system includes a mounting assembly 1; the mounting assembly 1 is U-shaped; the mounting assembly 1 is connected to the motor mounting platform 7;

[0050] Magnetic field component 2; the magnetic field component 2 is disposed within the U-shaped groove of the mounting component 1;

[0051] Infrared thermal imaging detector 8; the infrared thermal imaging detector 8 is disposed at the axisymmetric center of the mounting assembly 1;

[0052] 9. Laser source.

[0053] In this invention, the magnetic field component 2 is preferably a magnetic block or an alternating magnetic field; the invention uses a preset temperature range for the magnetic field to move the magnetic field component 2 to a position where the deposited layer meets the temperature range of the magnetic field during the printing process, and performs in-situ heat treatment on the deposited layer; the laser source 9 is preferably generated by a laser stereolithography device; the infrared thermal imaging detector 8 is preferably located at the axisymmetric center of the mounting component 1; during the laser additive manufacturing process, the infrared thermal imaging detector 8 is preferably used to synchronously track the actual temperature of the deposited layer, and the in-situ heat treatment is performed by controlling the dwell position and action time of the magnetic field component 2 according to the temperature requirements of in-situ heat treatment obtained from thermal analysis, using the robotic arm 5; the invention preferably uses nickel-based high-temperature alloy powder in the LAM system and fills it with a protective gas; the protective gas is preferably nitrogen.

[0054] The in-situ heat treatment apparatus provided by the present invention preferably further includes a connection system; the connection system preferably includes a worktable 3. In the present invention, when performing in-situ heat treatment on a laser additive manufacturing nickel-based superalloy, the base 4 of the mechanical control system is preferably placed on the worktable 3, and the specific structure is as follows: Figure 1 As shown.

[0055] Figure 2 The flowchart below shows the in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys provided by this invention. Figure 2 Detailed Explanation: This invention first determines the in-situ heat treatment scheme for the alloy through thermal analysis. Based on the sliced ​​and layered data imported into the LAM system using 3D CAD model software, 3D printing is performed. A temperature range for the action of the transverse static magnetic field is preset. During the printing process, an infrared thermal imager is used to detect the temperature of the deposited layer of the nickel-based superalloy. The deposited layer is then subjected to in-situ heat treatment using the transverse static magnetic field and alternating magnetic field to complete the LAM system 3D printing. The resulting nickel-based superalloy has a uniform microstructure and is free of cracks.

[0056] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0057] Example 1

[0058] Taking nickel-based polycrystalline superalloy GH4099 as an example, the in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys includes the following steps:

[0059] (1) The temperature range for in-situ heat treatment of nickel-based polycrystalline superalloy GH4099 was determined to be 1080–1140 °C by differential scanning calorimetry.

[0060] (2) Prepare spherical powder of nickel-based polycrystalline high-temperature alloy GH4099, control the flowability to be no higher than 20s / 50g, the particle size to be 50~150μm, and the transverse static magnetic field strength to be 0.2T;

[0061] (3) Preheat the substrate and powder bed. The substrate is preheated to 310°C. Use LAM equipment to perform laser additive manufacturing on nickel-based polycrystalline high-temperature alloy GH4099. Set the laser power to 1400W, the scanning speed to 700mm / min, and the powder feeding speed to 6g / min.

[0062] (4) Import the movement data of the mechanical control system, and the robotic arm 5 moves the transverse static magnetic field to perform in-situ heat treatment on the deposited layer of laser additive manufacturing to obtain nickel-based polycrystalline high temperature alloy GH4099.

[0063] (5) The nickel-based polycrystalline superalloy GH4099 was sequentially cut, polished, and etched. Its microstructure was observed using a scanning electron microscope, and the results are as follows: Figure 3 As shown. According to Figure 3 It can be seen that the nickel-based polycrystalline superalloy GH4099 prepared in this embodiment has a uniform microstructure and no obvious structural defects such as cracks.

[0064] Example 2

[0065] Taking nickel-based single-crystal superalloy DD5 as an example, the in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys includes the following steps:

[0066] (1) The temperature range for in-situ heat treatment of nickel-based single-crystal superalloy DD5 was determined to be 1270–1300 °C by differential scanning calorimetry.

[0067] (2) Prepare nickel-based single crystal high-temperature alloy DD5 spherical powder, control the flowability to be no higher than 20s / 50g, the particle size to be 50~150μm, and the transverse static magnetic field strength to be 0.1T;

[0068] (3) Preheat the substrate and powder bed. The substrate is preheated to 50°C. The nickel-based single crystal high-temperature alloy DD5 is epitaxially grown using LAM equipment. The laser power is set to 1300W, the scanning speed is 420mm / min, and the powder feeding speed is 6g / min.

[0069] (4) Import the movement data of the mechanical control system, and the robotic arm 5 moves the alternating magnetic field to perform in-situ heat treatment on the printed layer of laser additive manufacturing to obtain nickel-based single crystal high temperature alloy DD5.

[0070] (5) The nickel-based single crystal high-temperature alloy DD5 was cut, polished and etched, and its microstructure was observed using an optical microscope and a scanning electron microscope;

[0071] (6) The in-situ heat treatment temperature range of DD5 single crystal under magnetic field was optimized to 1250~1350℃.

[0072] (7) The optimized nickel-based single-crystal superalloy DD5 was cut, polished, and etched. Its microstructure was observed using a scanning electron microscope. The results are as follows: Figure 4 As shown. According to Figure 4 It can be seen that the nickel-based single-crystal superalloy DD5 prepared in this embodiment has a uniform microstructure and no obvious structural defects such as cracks.

[0073] As can be seen from the above embodiments, the in-situ heat treatment method provided by the present invention can better control the microstructure growth of nickel-based superalloys, regulate the element distribution and precipitate size, reduce component segregation and residual stress, and avoid the generation of cracks in nickel-based superalloys.

[0074] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys, characterized in that, Includes the following steps: Nickel-based superalloy powder is subjected to laser additive manufacturing, and the residual heat from laser additive manufacturing is used to perform in-situ heat treatment on the deposited layer; the in-situ heat treatment is performed under magnetic field conditions. The temperature of the region where the magnetic field acts is not lower than the γ' phase dissolution temperature of the nickel-based superalloy and not higher than the solidus temperature. The duration of the magnetic field is the time during which the temperature of the deposited layer of the nickel-based superalloy remains between the γ' phase dissolution temperature and the solidus temperature. The magnetic field is a transverse static magnetic field or an alternating magnetic field; The magnetic field moves through the deposited layer; the temperature of the area affected by the magnetic field is simultaneously tracked by an infrared thermal imaging detector.

2. The in-situ heat treatment method according to claim 1, characterized in that, The strength of the magnetic field is no higher than 1T.

3. The in-situ heat treatment method according to claim 1, characterized in that, The laser power in the laser additive manufacturing is 1200~2000W.

4. The in-situ heat treatment method according to claim 1, characterized in that, The temperature of the area affected by the magnetic field is 600~1350℃, and the duration of the magnetic field's effect does not exceed 5 minutes.

5. The in-situ heat treatment method according to claim 1, characterized in that, The nickel-based superalloy is a precipitation-strengthened nickel-based superalloy; the precipitation-strengthened nickel-based superalloy is a nickel-based polycrystalline alloy or a nickel-based single-crystal alloy.

6. The in-situ heat treatment method according to claim 1 or 3, characterized in that, The substrate used in the laser additive manufacturing includes a nickel-based high-temperature alloy substrate or a stainless steel substrate; the preheating temperature of the substrate is 200~1150℃.

7. The in-situ heat treatment method according to claim 1 or 5, characterized in that, The flowability of the nickel-based high-temperature alloy powder is not higher than 30s / 50g, and the particle size is 50~150μm.

8. An in-situ heat treatment apparatus for laser additive manufacturing of nickel-based superalloys, used to implement the in-situ heat treatment method for laser additive manufacturing of nickel-based superalloys as described in claim 1, characterized in that, Including mechanical control systems and magnetic field control systems: The mechanical control system includes a base (4); Robotic arm (5); the robotic arm (5) and the base (4) are movably connected; Motor (6); said motor (6) is used to provide power to the robotic arm (5); Motor mounting platform (7); the motor (6) is mounted on the mechanical control system of the motor mounting platform (7); The magnetic field control system includes a mounting assembly (1); the mounting assembly (1) is U-shaped; the mounting assembly (1) is connected to the motor mounting platform (7); Magnetic field component (2); the magnetic field component (2) is disposed in the U-shaped groove of the mounting component (1); Infrared thermal imaging detector (8); the infrared thermal imaging detector (8) is disposed at the axisymmetric center of the mounting assembly (1); Laser source (9).

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