Blisk linear friction welding joint current assisted local performance regulation method

Abstract

A kind of integral blade linear friction welding joint current auxiliary local performance regulation method, steps are as follows: preparation of shaper equipment;Welding seam necking transition section is machined;Integral blade is sent into vacuum environment device;Welding seam installs electrode, electrode is connected into direct current pulse power;Cooling device is connected;Vacuum environment device, cooling device and direct current pulse power are started in turn;Temperature reaches value and keeps warm;Adjust pulse current value to carry out secondary or more local heat treatment, close direct current pulse power;Cool to normal temperature;Restore normal pressure environment, cooling device is closed, electrode is removed;Repeat operation, complete the rest of welding seam local performance regulation.The present application utilizes the joule heating effect and electrocaloric effect generated by current through metal to realize local performance regulation of welded joint, combined with necking transition section to improve current density, realize accurate regulation of microstructure and mechanical properties of welded joint, realize high-performance, high-quality manufacturing of titanium alloy linear friction welding fan integral blade.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine component manufacturing technology, and in particular relates to a current-assisted local performance control method for linear friction welded joints of integral bladed disks. Background Technology

[0002] Linear friction welding is a solid-state welding method that achieves good metallurgical bonding by causing large plastic deformation at the interface to be welded under the mutual coupling of heat generated by metal friction, heat generated by plastic deformation, and welding pressure. This results in the formation of a dense and fine recrystallized structure.

[0003] Compared to fusion welding methods such as laser welding and electron beam welding, linear friction welding does not involve melting and solidification processes. Therefore, it usually does not encounter welding problems such as coarse microstructure and uneven element distribution. At the same time, it has advantages such as dense weld joint microstructure, mechanical properties comparable to the base material, and stable welding process and quality.

[0004] Therefore, linear friction welding technology is widely used in the high-quality welding of titanium alloy fan blades and disks for aero-engines to manufacture high-performance integral bladed disk components.

[0005] In the linear friction welding process of homogeneous / heterogeneous titanium alloys, the highest temperature at the welding interface can reach over 1200℃, exceeding the β phase transformation temperature of titanium alloys. At the same time, due to the short welding time, the heating and cooling process is usually completed within tens of seconds, which causes a violent phase transformation to occur at the welding interface.

[0006] Furthermore, the large plastic deformation process also leads to significant microstructural refinement of the material at the weld joint and generates substantial residual stress. These changes in microstructure and mechanical properties resulting from the welding process can typically only be controlled through post-weld heat treatment of the integral bladed disk.

[0007] However, due to the limitations of the heat treatment temperature of the blade and disk base material, the heat treatment temperature of the overall bladed disk after welding usually cannot exceed the aging temperature of the blade and disk base material. This will seriously weaken the heat treatment control effect of the linear friction welded joint, resulting in slow growth of fine microstructure at the weld and a large microstructure gradient with the base material. Furthermore, it is difficult to achieve precise control of the morphology and size of the α and β phases inside the titanium alloy at a lower temperature.

[0008] In summary, all of these factors reduce the service performance of the integral bladed disk of the titanium alloy linear friction welded fan, thereby affecting the performance indicators of the aero-engine. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides a current-assisted local performance control method for linear friction welded joints of integral bladed disks. Utilizing the Joule heating effect and electro-induced phase transition effect generated by current passing through the metal, and by processing a necking transition section at the weld joint to increase the current density at the weld joint, this method achieves localized heat treatment of the weld joint area of ​​the integral bladed disk. It overcomes the limitation of heat treatment aging temperature by the heat treatment temperature of the blade and disk base material, promoting the effective growth of excessively fine microstructures at the weld joint and forming a good, uniform transition with the base material. Based on the strengthening mechanism of titanium alloy, the size and morphology of the α and β phases are controlled, thereby achieving precise control of the microstructure and mechanical properties of the weld joint, and realizing high-performance, high-quality manufacturing of titanium alloy linear friction welded fan integral bladed disks.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a method for current-assisted local performance control of a linear friction welded joint of an integral bladed disk, comprising the following steps:

[0011] Step 1: Prepare equipment for local performance control of the welded joint, including a vacuum environment device, a DC pulse power supply, electrodes, a temperature measuring device, and a cooling device;

[0012] Step 2: A necking transition section is machined at the weld joint between the blades and the disk body of the integral bladed disk using machining methods;

[0013] Step 3: After the necking transition section is processed, the integral bladed disk is sent into the vacuum environment device. An insulating and heat-insulating platform is pre-set in the vacuum environment device. The integral bladed disk needs to be fixedly installed on the insulating and heat-insulating platform.

[0014] Step 4: Install electrodes on the blade end and disk end of the weld at the weld joint, and connect the electrodes on both sides of the weld at the weld joint to the positive and negative terminals of the DC pulse power supply through wires.

[0015] Step 5: Connect the cooling device to the electrode;

[0016] Step Six: Activate the vacuum environment device to place the entire impeller disk in a vacuum environment;

[0017] Step 7: Activate the cooling device to cool the electrodes;

[0018] Step 8: Turn on the DC pulse power supply to allow the pulse current to flow through the welding joint area, and use a temperature measuring device to monitor the temperature of the welding joint area in real time.

[0019] Step 9: Once the temperature at the welded joint reaches the set value, maintain the temperature for the set time.

[0020] Step 10: Based on the material microstructure evolution and performance requirements of the welded joint, perform secondary or more local heat treatments by adjusting the pulse current value, then gradually reduce the pulse current value until it reaches zero, and then turn off the DC pulse power supply.

[0021] Step 11: When the temperature at the welded joint drops to the set value, the vacuum environment is restored to normal pressure, the cooling device is turned off, the electrodes are removed, and the local performance control of the weld at the first welded joint on the integral bladed disk is completed.

[0022] Step 12: Repeat steps 4 to 11 until the local performance adjustment of the welds at the remaining welded joints on the overall bladed disk is completed.

[0023] The dimensions of the necking transition section are determined based on the electrothermal relationship and thermal conductivity of the blades and the base material of the integral bladed disk.

[0024] The cooling device is connected to the electrode and the single-unit straightening fixture in an embedded or bonded manner, and the cooling medium of the cooling device is a water-cooled medium or an air-cooled medium.

[0025] The temperature measuring device is either a contact thermocouple or a non-contact infrared thermometer. When the temperature measuring device is a contact thermocouple, it needs to be installed separately at the welding joint after the electrode is installed.

[0026] The base materials of the blades and the disk are homogeneous alloys or dissimilar alloys. When adjusting local performance, the temperature range for heat preservation is 600℃~1200℃, and the heat preservation time range is 15min~300min.

[0027] The beneficial effects of this invention are:

[0028] The present invention discloses a current-assisted local performance control method for integral bladed disk linear friction welding joints. This method utilizes the Joule heating effect and electro-induced phase transition effect generated by current passing through metal, and increases the current density at the weld joint by processing a necking transition section at the weld seam. This achieves local heat treatment of the weld seam of the integral bladed disk linear friction welding joint, overcoming the limitation of heat treatment aging temperature by the heat treatment temperature of the blade and disk base material. It can promote the effective growth of excessively fine microstructures at the weld joint and form a good uniform transition with the base material. Based on the strengthening mechanism of titanium alloy, the method controls the size and morphology of the α phase and β phase, thereby achieving precise control of the microstructure and mechanical properties of the weld joint, and realizing high-performance and high-quality manufacturing of titanium alloy linear friction welded fan integral bladed disks. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the integral bladed disk structure;

[0030] Figure 2This is a schematic diagram of current-assisted local performance regulation at the welded joint of an integral bladed disk.

[0031] In the figure, 1—DC pulse power supply, 2—electrode, 3—blade, 4—disc body, 5—necked transition section, 6—weld at the welded joint. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0033] A method for current-assisted local performance control of linear friction welded joints of integral bladed disks includes the following steps:

[0034] Step 1: Prepare equipment for local performance control of the welded joint, including a vacuum environment device, a DC pulse power supply 1, an electrode 2, a temperature measuring device, and a cooling device;

[0035] Step 2: Machining Figure 1 A necked transition section 5 is machined at the weld joint 6 of the integral bladed disk blade 3 and the disk body 4. The size of the necked transition section 5 is determined according to the electrothermal relationship and thermal conductivity of the base materials of the integral bladed disk blade 3 and the disk body 4. In this embodiment, the necked transition section 5 is machined by milling. The necked transition section 5 forms a small cross-sectional structure with a reduced diameter relative to the weld joint. The groove cross-section of the necked transition section 5 is an arc surface. Since the cross-sectional area of ​​the weld where the necked transition section 5 is located is smaller, the current density at the small cross-section can be effectively increased, thereby causing the temperature to rise rapidly.

[0036] Step 3: The integral bladed disk after the necking transition section 5 is processed is sent into the vacuum environment device. An insulating and heat-insulating platform is pre-set in the vacuum environment device. The integral bladed disk needs to be fixedly installed on the insulating and heat-insulating platform. In this embodiment, the integral bladed disk can be mechanically fixed on the insulating and heat-insulating platform using a general-purpose tooling fixture. There is no need to design and manufacture new tooling fixtures separately.

[0037] Step 4: Install electrodes 2 on the blade end and disk end of weld 6 at the weld joint, respectively. Connect the electrodes 2 on both sides of weld 6 at the weld joint to the positive and negative terminals of the DC pulse power supply 1 via wires, as follows: Figure 2 As shown; in this embodiment, electrode 2 is a low resistivity copper electrode, which is installed by clamping. During the installation process, attention should be paid to adjusting the clamping force of electrode 2 to prevent arcing during the power-on process.

[0038] Step 5: Connect the cooling device to electrode 2. The cooling device can be embedded or attached to electrode 2. The cooling medium of the cooling device can be water-cooled or air-cooled.

[0039] Step Six: Activate the vacuum environment device to place the entire bladed disk under vacuum. In this embodiment, when the base material of the blade 3 and the disk body 4 is the same titanium alloy, the vacuum degree is controlled to be no greater than 1×10⁻⁶. -2 When the base materials of blade 3 and disk 4 are TC4 / TC17 dissimilar titanium alloys, the vacuum degree is controlled to be no greater than 5 × 10⁻⁶. -3 pa; to prevent adverse conditions such as surface oxidation and hydrogen absorption caused by high temperatures during subsequent local heat treatment;

[0040] Step 7: Activate the cooling device to cool electrode 2. In this embodiment, cooling electrode 2 can prevent the temperature of the welding joint from being conducted to the main body of the blade and the disk, and prevent the high temperature of local heat treatment from affecting the performance of the blade and the disk. Specifically, it is used to ensure that the temperature of electrode 2 does not exceed 100°C.

[0041] Step 8: Start the DC pulse power supply 1 to allow the pulse current to flow through the welding joint. The temperature of the welding joint is monitored in real time by a temperature measuring device, which can be a contact thermocouple or a non-contact infrared thermometer. When a contact thermocouple is used, it needs to be installed separately on the welding joint after the electrode 2 is installed. In this embodiment, the pulse current of the DC pulse power supply 1 can be adjusted within the range of 0 to 30000A.

[0042] Step Nine: After the temperature at the welded joint reaches the set value, maintain the temperature for a set time. If the base materials of blade 3 and disk 4 are homogeneous or dissimilar alloys, the temperature range for maintaining the temperature during local performance control is 600℃~1200℃, and the time range is 15min~300min. In this embodiment, when the base materials of blade 3 and disk 4 are homogeneous titanium alloys, the temperature for maintaining the temperature is controlled at 630℃~1100℃, and the time is controlled at 30min~180min. When the base materials of blade 3 and disk 4 are TC4 / TC17 dissimilar titanium alloys, the temperature for maintaining the temperature is controlled at 800℃~900℃, and the time is controlled at 60min~90min.

[0043] Step 10: Based on the material microstructure evolution and performance requirements of the welded joint, perform secondary or more local heat treatments by adjusting the pulse current value, then gradually reduce the pulse current value until it reaches zero, and then turn off the DC pulse power supply 1; In this embodiment, when the base material of the blade 3 and the disk 4 is a homogeneous titanium alloy, only one local heat treatment is performed; when the base material of the blade 3 and the disk 4 is a TC4 / TC17 dissimilar titanium alloy, a secondary local heat treatment is performed, by reducing the pulse current value to lower the temperature to 630℃~650℃, and the holding time is controlled at 60min~90min;

[0044] Step 11: After the temperature at the weld joint drops to the set value, the vacuum environment device returns to normal pressure, the cooling device is turned off, electrode 2 is removed, and the local performance control of the weld 6 at the first weld joint on the integral bladed disk is completed. In this embodiment, when the base material of the blade 3 and the disk 4 is the same titanium alloy, the vacuum environment device returns to normal pressure after the temperature at the weld joint drops below 150°C; when the base material of the blade 3 and the disk 4 is TC4 / TC17 dissimilar titanium alloy, the vacuum environment device returns to normal pressure after the temperature at the weld joint drops below 100°C.

[0045] Step 12: Repeat steps 4 to 11 until the local performance adjustment of weld 6 at the remaining welded joints on the overall bladed disk is completed.

[0046] The solutions described in the embodiments are not intended to limit the scope of patent protection of this invention. All equivalent implementations or modifications that do not depart from the scope of this invention are included in the patent scope of this case.

Claims

1. A method for current-assisted local performance control of a linear friction welded joint of an integral bladed disk, characterized in that... Includes the following steps: Step 1: Prepare equipment for local performance control of the welded joint, including a vacuum environment device, a DC pulse power supply, electrodes, a temperature measuring device, and a cooling device; Step 2: A necking transition section is machined at the weld joint between the blades and the disk body of the integral bladed disk using machining methods; Step 3: After the necking transition section is processed, the integral bladed disk is sent into the vacuum environment device. An insulating and heat-insulating platform is pre-set in the vacuum environment device. The integral bladed disk needs to be fixedly installed on the insulating and heat-insulating platform. Step 4: Install electrodes on the blade end and disk end of the weld at the weld joint, and connect the electrodes on both sides of the weld at the weld joint to the positive and negative terminals of the DC pulse power supply through wires. Step 5: Connect the cooling device to the electrode; Step Six: Activate the vacuum environment device to place the entire impeller disk in a vacuum environment; Step 7: Activate the cooling device to cool the electrodes; Step 8: Turn on the DC pulse power supply to allow the pulse current to flow through the welding joint area, and use a temperature measuring device to monitor the temperature of the welding joint area in real time. Step 9: Once the temperature at the welded joint reaches the set value, maintain the temperature for the set time. Step 10: Based on the material microstructure evolution and performance requirements of the welded joint, perform secondary or more local heat treatments by adjusting the pulse current value, then gradually reduce the pulse current value until it reaches zero, and then turn off the DC pulse power supply. Step 11: When the temperature at the welded joint drops to the set value, the vacuum environment is restored to normal pressure, the cooling device is turned off, the electrodes are removed, and the local performance control of the weld at the first welded joint on the integral bladed disk is completed. Step 12: Repeat steps 4 to 11 until the local performance adjustment of the welds at the remaining welded joints on the overall bladed disk is completed.

2. The method for current-assisted local performance control of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The dimensions of the necking transition section are determined based on the electrothermal relationship and thermal conductivity of the blades and the base material of the integral bladed disk.

3. The method for current-assisted local performance control of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The cooling device is connected to the electrode and the single-unit straightening fixture in an embedded or bonded manner, and the cooling medium of the cooling device is a water-cooled medium or an air-cooled medium.

4. The method for current-assisted local performance control of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The temperature measuring device is either a contact thermocouple or a non-contact infrared thermometer. When the temperature measuring device is a contact thermocouple, it needs to be installed separately at the welding joint after the electrode is installed.

5. The method for current-assisted local performance control of a linear friction welded joint of an integral bladed disk according to claim 1, characterized in that: The base materials of the blades and the disk are homogeneous alloys or dissimilar alloys. When adjusting local performance, the temperature range for heat preservation is 600℃~1200℃, and the heat preservation time range is 15min~300min.

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