High-temperature alloy precipitated phase regulation and control method based on electric field auxiliary forming

Abstract

A high-temperature alloy precipitated phase regulation and control method based on electric field auxiliary forming comprises the steps that a precipitated phase in a matrix is dissolved through solid solution / sub-solid solution temperature pretreatment of a high-temperature alloy, and a uniform supersaturated solid solution is obtained; then performing electric field assisted high-temperature deformation on the high-temperature alloy supersaturated solid solution, applying an electric field to the high-temperature alloy to heat the high-temperature alloy to a target temperature, then performing thermal deformation, and regulating and controlling the precipitated phase of the high-temperature alloy by adjusting the strain rate and the current parameter of the auxiliary electric field in the thermal deformation process; the precipitated phase in the as-cast alloy is dissolved through pretreatment before thermal deformation, the supersaturation degree of a matrix is improved, the deformation resistance is reduced, and meanwhile a foundation is provided for regulation and control of the precipitated phase; meanwhile, by means of the influence of dislocation and an electric field on the diffusion behavior of component elements of the precipitated phase, more freedom degrees are provided for regulation and control of the precipitated phase of the high-temperature alloy by regulating and controlling the strain rate related to dislocation density, current parameters related to the electric field effect and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material forming and manufacturing, and in particular relates to a method for regulating and controlling precipitation phases of high-temperature alloys based on electric field assisted forming. Background Art

[0002] The microstructure of metal materials directly determines their service performance. In the process of forming and manufacturing metal components, the mechanical, physical, and chemical properties can be effectively given or improved by regulating their microstructure. As a typical precipitation-strengthened alloy, the precipitated phase in the high-temperature alloy usually plays a decisive role in its mechanical properties and fatigue properties. By adjusting the size, distribution, and morphology of the precipitated phase, the performance of the high-temperature alloy can be optimized.

[0003] At present, the regulation of precipitation phases in high-temperature alloys is mainly achieved by changing parameters such as the heating temperature and holding time of heat treatment, and the process freedom that can be regulated is relatively limited; and there are obvious differences in the precipitation temperature ranges corresponding to different precipitation phases in high-temperature alloys, which often requires multiple stages of heat treatment. The process flow is long and there may be mutual interference between the regulation of multiple precipitation phases during the regulation process; in addition, heat treatment is usually achieved by radiation heating of a heating furnace. The heat of the material is transferred from the surface to the core. There are differences in the thermal history of different parts, which often leads to uneven distribution of precipitation phases.

[0004] As a high-strength material, high-temperature alloys have high deformation resistance during hot deformation processing, which often requires the use of heavy forging equipment or multiple deformation accumulations to achieve effective forging forming, resulting in very high manufacturing costs for high-temperature alloys. Electric field assisted forming technology (Ding Junhao, Li Heng, Bian Tianjun, et al. Research trends and prospects of electroplasticity and current assisted forming [J]. Acta Aeronautica Sinica, 2018, 39(1): 21201-021201.) uses the Joule effect and electroplasticity effect generated when current passes through the material to improve the grain size and mechanical properties of the material during forming, which has the advantages of reducing forming force, energy saving and environmental protection. However, for high-temperature alloys containing high volume fraction precipitation phases, the regulation of precipitation phases is more important than grain size. At present, there are few literature reports on the use of current assistance to regulate the precipitation phase of high-temperature alloys during hot deformation. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for regulating the precipitation phase of a high-temperature alloy based on electric field assisted forming, by pretreatment before hot deformation, dissolving the precipitated phase in the cast alloy, increasing the supersaturation of the matrix, and thereby reducing the deformation resistance during the hot deformation process while providing a basis for regulating the precipitated phase; at the same time, by utilizing the influence of dislocations and electric fields on the diffusion behavior of the constituent elements of the precipitated phase, more degrees of freedom are provided for regulating the precipitated phase of the high-temperature alloy by regulating the strain rate related to the dislocation density and the current parameters related to the electric field (current type, current direction, etc.); in addition, since the electric field-assisted Joule heating effect occurs evenly in various parts of the material, it also provides favorable conditions for improving the uniformity of the spatial distribution of the precipitated phase.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for regulating the precipitation phase of a high-temperature alloy based on electric field assisted forming comprises the following steps:

[0008] Step 1, pretreating the as-cast high-temperature alloy sample: after keeping the high-temperature alloy at the solid solution / sub-solid solution temperature, cooling to room temperature, dissolving and separating the phases, and obtaining a uniform supersaturated solid solution of the high-temperature alloy;

[0009] Step 2, thermally deforming the supersaturated solid solution of the high-temperature alloy obtained in step 1: applying electric field heating to the high-temperature alloy to perform thermal deformation, and adjusting the strain rate and current parameters of the auxiliary electric field during the thermal deformation process to achieve regulation of the precipitation phase of the high-temperature alloy, and air cooling to room temperature after the thermal deformation is completed.

[0010] Step 1 uses a heating furnace, the sample is heated with the furnace, the heating rate is 8-10°C / min, the pretreatment temperature is 1085-1105°C, the insulation time is 4-4.5h, and the sample is air-cooled to room temperature after the insulation is completed.

[0011] Step 2 uses an electric field assisted thermal deformation device, with positive and negative electrodes connected to both ends of the high-temperature alloy, the voltage is controlled to 1.5-2.0V, the current is 1000-2000A, the heating rate is 8-10℃ / S, the deformation temperature is 900-1100℃, the insulation time is 3-5min, and the insulation is air-cooled to room temperature after the insulation is completed; thermocouples are welded at different parts of the high-temperature alloy for temperature feedback and control, using 0.001-1.0s -1 The target strain rate is 0.3-0.4, and the alloy is compressed and deformed at high temperature. After the deformation, the alloy is taken out and air-cooled to room temperature to obtain a precipitation phase-regulated high-temperature alloy assisted by electric field high-temperature compression.

[0012] Step 2: There are two deformation modes for regulating the precipitation phase during the thermal deformation process. One is to maintain a constant strain rate to the target deformation amount; the other is to continuously change the strain rate to the target deformation amount at multiple strain rates, that is, at 0.001~1.0s -1 The deformation is carried out at a certain strain rate within a certain range to a certain deformation amount or switched to another strain rate for deformation.

[0013] The electric field assisted thermal deformation device in step 2 includes a displacement acquisition system 1, a heating device 3 and a current feedback control device 4;

[0014] The displacement acquisition system 1 is composed of a clamping mechanism and a data acquisition mechanism. The clamping mechanism clamps and fixes the sample 2, and the data acquisition mechanism collects the displacement, temperature, and current data of the sample 2;

[0015] The heating device 3 adopts a resistive heating method, and heats the sample 2 by passing a current of thousands of amperes through the cross section of the sample 2;

[0016] The current feedback control device 4 collects the temperatures of different parts of the sample 2 through thermocouples, and controls the current in the heating device 3 by feedback to adjust the heating temperature of the sample 2.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention can not only reduce deformation resistance by pretreatment before deformation and regulating the precipitated phase during hot deformation, but also utilize the influence of dislocation and current on element diffusion to provide more degrees of freedom for regulating the volume fraction, size distribution, spatial distribution and morphology of the high-temperature alloy precipitated phase.

[0019] 2. The present invention can effectively reduce the multi-step heat treatment process in the existing process oriented to the control of precipitation phase by coordinating multiple process parameters of thermal deformation to accurately control the precipitation phase of the high-temperature alloy, shorten the high-temperature alloy manufacturing process, and avoid the occurrence of organizational problems such as grain coarsening and abnormally large grains caused by long-term heat treatment.

[0020] 3. The present invention can effectively achieve uniform heating in the hot forming of high-strength materials such as high-temperature alloys, reduce the pressure requirements of forming equipment, shorten the process flow, thereby reducing energy consumption, improving production efficiency, and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of the electric field assisted thermal deformation device according to an embodiment of the present invention.

[0022] Figure 2 It is a comparison diagram of stress-strain curves of the electrically assisted thermal deformation of the high-temperature alloy of the embodiment of the present invention and the conventional thermal deformation of the comparative example.

[0023] Figure 3 The precipitation phase and particle size distribution diagram of the high temperature alloy of the present invention, wherein (a) is the original precipitation phase; (b) is the particle size distribution of the original precipitation phase; (c) is 0.001S -1 Precipitation phase of thermal deformation; (d) is 0.001S -1 Particle size distribution of precipitated phase during thermal deformation; (e) is 0.1S -1 Precipitation phase of thermal deformation; (f) is 0.1S -1 Particle size distribution of precipitation phase during thermal deformation. DETAILED DESCRIPTION

[0024] The present invention is described in more detail below with reference to the embodiments and the accompanying drawings.

[0025] Embodiment: This embodiment adopts the cast GH4720Li nickel-based high-temperature alloy, and a high-temperature alloy precipitation phase control method based on electric field assisted forming includes the following steps:

[0026] Step 1, pretreating the as-cast high-temperature alloy sample: using a conventional heating furnace, the sample is heated with the furnace, the heating rate is 10°C / min, the pretreatment temperature is 1090°C, and the temperature is kept for 4 hours. After the temperature is kept, the sample is taken out of the furnace and air-cooled to room temperature; the precipitate phase in the as-cast alloy is dissolved by pretreatment to obtain a uniform supersaturated solid solution of the high-temperature alloy, which provides a basis for the subsequent regulation of the precipitate phase based on electric field assisted forming;

[0027] Step 2: The supersaturated solid solution of the high-temperature alloy obtained in step 1 is subjected to high-temperature compression by an electric field-assisted thermal deformation device: the two ends of the high-temperature alloy are connected to positive and negative electrodes, the voltage is 1.5V, the current is 1500A, and it is heated to 1000℃ at a heating rate of 10℃ / S, and kept warm for 5 minutes; thermocouples are welded at different parts of the high-temperature alloy for temperature feedback and control, and the temperature is adjusted by 0.001~1.0s. -1 The sample was subjected to high temperature compression deformation with a strain rate of 0.4, and was immediately taken out and air-cooled to room temperature after the deformation to obtain a sample regulated by electric field-assisted high temperature compression precipitation phase.

[0028] Reference Figure 1 The electric field assisted thermal deformation device described in step 2 includes a displacement acquisition system 1, a heating device 3 and a current feedback control device 4;

[0029] The displacement acquisition system 1 is composed of a clamping mechanism and a data acquisition mechanism. The clamping mechanism clamps and fixes the sample 2, and the data acquisition mechanism collects data such as displacement, temperature, and current of the sample 2;

[0030] The heating device 3 adopts a resistive heating method, and heats the sample 2 by passing a current of thousands of amperes through the cross section of the sample 2;

[0031] The current feedback control device 4 collects the temperatures of different parts of the sample 2 through thermocouples, and controls the current in the heating device 3 by feedback to adjust the heating temperature of the sample 2.

[0032] In the comparative example, the material preparation before hot deformation is the same as step 1 of the embodiment, except that the heating method for high temperature compression in step 2 is carried out by a conventional heating furnace, that is, the surrounding environment of the high temperature alloy is heated, and the material itself is heated by heat conduction, and the other test conditions remain unchanged. Compared with electric field assisted hot deformation, the yield stress is high and the deformation resistance is large.

[0033] like Figure 2 As shown, 0.001 to 1.0 s in this embodiment -1 The stress-strain curve under strain rate shows that the yield stress of the material under the electric field assistance shows a downward trend compared with the conventional high-temperature compression test of the comparative example.

[0034] The high-temperature alloy obtained in this embodiment was cut longitudinally, subjected to standard metallographic grinding and polishing, electrolytic corrosion was performed using a certain concentration of corrosive solution, and the precipitate phase characteristics were analyzed under a scanning electron microscope to obtain information such as the volume fraction, size, and morphology of the precipitate phase; Figure 3 As shown, 0.001s -1 and 0.1s -1 The morphology and particle size distribution of the precipitated phase in the electric field-assisted hot deformation high-temperature alloy under strain rate show that the precipitated phase is uniformly distributed in space, but there are obvious differences in volume fraction and size distribution, indicating the effectiveness of regulating the precipitated phase by adjusting the electric field-assisted hot deformation strain rate.

[0035] In summary, the innovation of the present invention lies in that the original precipitated phase in the cast high-temperature alloy is dissolved back by pretreatment before hot deformation, thereby reducing the deformation resistance during hot deformation. At the same time, the electric field is combined with a more uniform heating effect, the deformation introduces dislocations, and the influence of current parameters on the diffusion of alloy elements, etc., which provide more freedom for the regulation of the precipitation phase of the high-temperature alloy. While regulating the volume fraction, size, morphology, etc. of the precipitated phase, the forming and manufacturing of heterogeneous high-temperature alloys with gradient precipitation phase distribution, interlayer precipitation phase distribution, etc. can also be realized.

[0036] The embodiments described above are only preferred embodiments of the present invention and do not represent limitations on the present invention. Any direct and equivalent modification, change or improvement based on the core principle of the present invention shall be deemed to be included in the protection scope of the present invention. The protection scope of the present invention shall be based on the claims, including but not limited to all possible equivalent implementations of the above embodiments.

Claims

1. A method for regulating the precipitation phase of a high-temperature alloy based on electric field assisted forming, characterized in that: The steps include: Step 1, pretreating the as-cast high-temperature alloy sample: after keeping the high-temperature alloy at the solid solution / sub-solid solution temperature, cooling to room temperature, dissolving and separating the phases, and obtaining a uniform supersaturated solid solution of the high-temperature alloy; Step 2, thermally deforming the supersaturated solid solution of the high-temperature alloy obtained in step 1: applying electric field heating to the high-temperature alloy to perform thermal deformation, and adjusting the strain rate and current parameters of the auxiliary electric field during the thermal deformation process to achieve regulation of the precipitation phase of the high-temperature alloy, and air cooling to room temperature after the thermal deformation is completed.

2. The method according to claim 1, characterized in that: Step 1 uses a heating furnace, the sample is heated with the furnace, the heating rate is 8-10°C / min, the pretreatment temperature is 1085-1105°C, the insulation time is 4-4.5h, and the sample is air-cooled to room temperature after the insulation is completed.

3. The method according to claim 1, characterized in that: Step 2 uses an electric field assisted thermal deformation device, with positive and negative electrodes connected to both ends of the high-temperature alloy, the voltage is controlled to 1.5-2.0V, the current is 1000-2000A, the heating rate is 8-10℃ / S, the deformation temperature is 900-1100℃, the insulation time is 3-5min, and the insulation is air-cooled to room temperature after the insulation is completed; thermocouples are welded at different parts of the high-temperature alloy for temperature feedback and control, using 0.001-1.0s -1 The target strain rate is 0.3-0.4, and the alloy is compressed and deformed at high temperature. After the deformation, the alloy is taken out and air-cooled to room temperature to obtain a precipitation phase-regulated high-temperature alloy assisted by electric field high-temperature compression.

4. The method according to claim 3, characterized in that: Step 2: There are two deformation modes for regulating the precipitation phase during the thermal deformation process. One is to maintain a constant strain rate to the target deformation amount; the other is to continuously change the strain rate to the target deformation amount at multiple strain rates, that is, at 0.001~1.0s -1 The deformation is carried out at a certain strain rate within a certain range to a certain deformation amount or switched to another strain rate for deformation.

5. The method according to claim 3, characterized in that: The electric field assisted thermal deformation device in step 2 comprises a displacement acquisition system (1), a heating device (3) and a current feedback control device (4); The displacement acquisition system (1) is composed of a clamping mechanism and a data acquisition mechanism, wherein the clamping mechanism clamps and fixes the sample (2), and the data acquisition mechanism collects displacement, temperature, and current data of the sample (2); The heating device (3) adopts a resistive heating method to heat the sample (2) by passing a current of thousands of amperes through the cross section of the sample (2); The current feedback control device (4) collects the temperature of different parts of the sample (2) through a thermocouple, and controls the current in the heating device (3) through feedback to adjust the heating temperature of the sample (2).

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