Method for predicting phase structure transformation of impeller material

Abstract

The invention provides a method for predicting phase structure transformation of an impeller material, which comprises the following steps of: S1, roughly machining a target workpiece, and cutting a test ring on the target workpiece; s2, performing heat treatment on the target workpiece and the test ring; s3, cutting a first sample on the test ring, applying different loading forces to the first sample for stretching, performing X-ray diffraction detection on the first sample when the different loading forces are applied, and forming a corresponding peak curve; according to the method, the first sample is subjected to performance sample stretching and X-ray diffraction detection, the volume percentage of the phase structure of the target workpiece before and after stretching is tested, the austenite volume structure tissue transformation condition of the impeller in the overspeed process is predicted, and the phase structure of the impeller can be stabilized in advance; and phase structure transformation in the overspeed test process is prevented, and the performance stability and reliability of the target workpiece in actual application are greatly improved.

Description

Technical Field

[0001] The present application belongs to the technical field of compressors, and specifically relates to a method for predicting the phase structure transformation of impeller materials. Background Art

[0002] The impeller is the heart of the centrifugal compressor and directly affects the overall safe operation of the compressor. Therefore, the quality of the impeller is of vital importance. According to the API617 standard, the impeller needs to be subjected to an overspeed test before assembly to check the deformation and surface quality of the impeller. Once the dimensional deviation of the impeller before and after the overspeed test exceeds the standard requirements, it is easy to cause the impeller to be scrapped, resulting in economic losses. There are many reasons for the impeller overspeed test deviation to exceed the standard, but it is difficult to detect in advance because the overspeed test deviation caused by the phase structure transformation of the impeller during the overspeed process is unqualified. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] In order to solve the above problems, the present application provides a method for predicting the phase structure transformation of impeller materials, comprising the following steps:

[0005] S1, rough machining the target workpiece and cutting a test circle on the target workpiece;

[0006] S2. Heat treatment of the target workpiece and the test circle;

[0007] S3, cutting a first sample from the test ring, applying different loading forces to the first sample for stretching, and performing X-ray diffraction detection on the first sample when the different loading forces are applied to form corresponding peak curves;

[0008] S4. Obtain the corresponding austenite volume content when different forces are applied to the first sample through the peak curve.

[0009] Optionally, before step S3, it is necessary to cut a second sample from the test ring and perform a tensile test on the second sample to obtain an actual yield strength. When the actual yield strength meets the design yield strength requirement, step S3 is performed.

[0010] Optionally, in step S3, the tensile loading force is increased from zero to the theoretical yield stress.

[0011] Optionally, in step S3, the stretching needs to be maintained for 0.5 minutes to 2 minutes during X-ray diffraction detection.

[0012] Optionally, the stretching needs to be maintained for 1 minute during X-ray diffraction detection.

[0013] Optionally, before step S1, a continuous cooling transformation curve needs to be measured for the target workpiece.

[0014] Optionally, the target workpiece includes a cover disk and a shaft disk, or an integrally machined impeller.

[0015] Optionally, in step S2, when the target workpiece and the test ring are heat treated, a process of adjustment treatment and aging treatment may be adopted, or a process of solution treatment, adjustment treatment and aging treatment may be adopted.

[0016] Beneficial Effects

[0017] A method for predicting the phase structure transformation of an impeller material provided in an embodiment of the present invention determines the mechanical properties of a target sample and the sampling position of a test circle by testing the hardenability of a target workpiece material, and tests the volume percentage of the phase structure of the target workpiece before and after stretching by stretching the performance sample of the first sample to predict the austenite volume structure transformation of the impeller during the overspeed process. The phase structure of the impeller can be stabilized in advance to prevent the phase structure transformation from occurring during the overspeed test, thereby greatly improving the performance stability and reliability of the target workpiece in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flowchart of this application;

[0019] Figure 2 The target workpiece structure diagram of this application;

[0020] Figure 3 This is the first sample structure diagram of this application;

[0021] Figure 4 This is an X-ray diffraction curve diagram of Example 1 of the present application when the tensile force is 0N;

[0022] Figure 5 This is an X-ray diffraction curve diagram of Example 1 of the present application when the tensile force is 1715N;

[0023] Figure 6 This is an X-ray diffraction curve diagram of Example 1 of the present application when the tensile force is 2744N;

[0024] Figure 7 This is the X-ray diffraction curve of Example 1 of the present application when the tensile force is 3430N.

[0025] The reference numerals are:

[0026] 1. Target workpiece; 2. Test circle; 3. First specimen. DETAILED DESCRIPTION

[0027] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred system or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] See also Figure 1-7 As shown, according to an embodiment of the present application, a method for predicting the phase structure transformation of an impeller material is provided, comprising the following steps:

[0032] S1, performing rough machining on the target workpiece 1, and cutting a test circle 2 on the target workpiece 1;

[0033] S2, heat treating the target workpiece 1 and the test circle 2;

[0034] S3, cutting a first sample 3 from the test circle 2, applying different loading forces to the first sample 3 to stretch it, and performing X-ray diffraction detection on the first sample 3 when applying different loading forces to form corresponding peak curves;

[0035] S4. Obtain the corresponding austenite volume content when different forces are applied to the first sample 3 through the peak curve.

[0036] Specifically, in step S1, the material of the target workpiece 1 is FV520B steel, 17-4PH steel or ASTM A705-630 steel, and a rough machining operation is performed on the target workpiece 1 to remove possible flaws, unevenness and defects left over from previous machining on the surface of the target workpiece 1 to ensure that its surface roughness, shape accuracy and other aspects meet subsequent process requirements, and a test circle 2 is cut from the target workpiece 1. The test circle 2 can fully represent the overall material properties of the target workpiece 1, and provide a reliable sample basis for subsequent testing and analysis.

[0037] In step S2, heat treatment is performed on the target workpiece 1 and the cut test circle 2. According to the mechanical property requirements of the target workpiece 1 material (such as a specific type of steel), a heat treatment process scheme is selected, which may include a combination or individual use of multiple process steps such as solid solution treatment, adjustment treatment, and aging treatment, and the test circle 2 and the target workpiece 1 are placed in a heat treatment furnace for treatment to ensure that the two undergo the same organizational transformation process under the same thermal environment, thereby maintaining a high degree of consistency in microstructure and macroscopic performance, so that the test data cut from the test circle 2 can truly and accurately reflect the actual situation of the target workpiece 1.

[0038] In step S3, a first sample 3 is cut from the test ring 2, and a series of different loading forces are applied to the first sample 3 to carry out a tensile test. During the stretching process, an in-situ X-ray microanalysis system tensile tester is used to perform X-ray diffraction detection on the first sample 3 at each different loading force application moment, accurately capturing the change information of the internal crystal structure of the material and forming a corresponding peak curve. This ensures that the X-ray diffraction detection can obtain stable and reliable crystal structure data, and then generate a peak curve with representativeness and analytical value.

[0039] In step S4, with advanced data analysis technology and professional calculation methods, according to relevant standards (such as YB / T538-2019 X-ray diffractometer method for quantitative determination of austenite in steel), the peak curve obtained in step S3 is analyzed and calculated to obtain the corresponding austenite volume content of the first sample 3 when different forces are applied. The volume percentage of the phase structure of the target workpiece 1 before and after stretching is used to predict the transformation of the austenite volume structure of the impeller during the overspeed process, and the phase structure of the impeller can be stabilized in advance to prevent the phase structure transformation during the overspeed test, which greatly improves the performance stability and reliability of the target workpiece 1 in practical applications.

[0040] Before step S3, it is necessary to cut a second sample from the test ring 2 and perform a tensile test on the second sample to obtain the actual yield strength. When the actual yield strength meets the design yield strength requirement, step S3 is performed.

[0041] Specifically, before entering step S3, it is necessary to cut a second sample on the test circle 2. The size of the second sample is based on GB / T228.1-2021 Metal Material Tensile Test Part 1: Room Temperature Tensile Method. The size of the cut second sample is accurate, the surface quality is good, and it can fully represent the material properties of the target workpiece 1 corresponding to the test circle 2. Subsequently, the cut second sample is subjected to a tensile test by a universal testing machine. During the tensile test, various data during the test are accurately recorded, and the actual yield strength of the second sample is accurately obtained by analyzing and processing the test data. Only when the measured actual yield strength meets the design yield strength requirements will step S3 be entered. In step S3, the first sample 3 is obtained on the test circle 2, and then different loading forces are applied to the first sample 3 for stretching, and when different loading forces are applied, the first sample 3 is subjected to X-ray diffraction detection and a corresponding peak curve is formed. If the actual yield strength does not meet the design requirements, it is necessary to re-evaluate and adjust the preliminary processing, material selection or heat treatment of the target workpiece 1 until the actual yield strength obtained by cutting a second sample for tensile testing meets the requirements.

[0042] Through the above-mentioned pre-control, it can be ensured that the subsequent various tests and analysis work based on the first sample 3 is established on the basis of the target workpiece 1 material performance meeting the standard, so that the corresponding austenite volume content when different forces are applied to the first sample 3 can be finally obtained through the peak curve, and the phase structure transformation of the target workpiece 1 under special working conditions (such as overspeed test) can be predicted with more accuracy and reliability, which effectively guarantees the stable performance of the target workpiece 1 in practical applications.

[0043] In step S3, the tensile loading force is increased from zero to the theoretical yield stress.

[0044] Specifically, in step S3, the tensile loading force of the first sample 3 starts from 0N and gradually increases until the theoretical yield force is reached. The theoretical yield force is equivalent to the result of multiplying the minimum value of the designed yield strength by the gauge cross-sectional area of ​​the first sample 3. In the initial stage, when the loading force is 0N, the first sample 3 is first subjected to an X-ray diffraction test of the initial state, which is used as a benchmark for subsequent test data comparison. As the test progresses, the loading force is increased slowly and steadily according to a predetermined loading force increment scheme, and the first sample 3 is subjected to an X-ray diffraction test at each key node of the loading force increase. For example, it can be set to perform X-ray diffraction tests and record the corresponding peak curves when the loading force reaches a certain proportion of the theoretical yield force (such as 50%, 80%, 100%, etc.).

[0045] During the entire process of increasing the loading force from 0N to the theoretical yield force, the in-situ X-ray microanalysis system tensile testing machine needs to maintain high-precision force control and data acquisition functions to ensure the accuracy and stability of the loading force, as well as the reliability of the X-ray diffraction test data. By performing X-ray diffraction testing on the first sample 3 at different loading force levels, it is possible to comprehensively and accurately capture the subtle changes in the internal crystal structure of the material as the external force increases, so as to accurately calculate the corresponding austenite volume content at different loading forces based on the peak curve formed, and then effectively predict the phase structure transformation of the target workpiece 1 in situations such as overspeed testing.

[0046] In step S3, the stretching needs to be maintained for 0.5 minutes to 2 minutes when performing X-ray diffraction detection.

[0047] When performing X-ray diffraction detection, the stretching needs to be maintained for 1 minute.

[0048] Specifically, in step S3, when performing X-ray diffraction detection on the first sample 3, after the loading force reaches the predetermined detection point and stabilizes, the timing is started to maintain the tensile state for 1 minute. During this period, the X-ray diffraction detection equipment detects the first sample 3 in the stable tensile stress state, and can accurately capture the characteristic information of the internal crystal structure of the material and generate a corresponding peak curve.

[0049] The 1-minute stretching duration is long enough for the atomic arrangement, lattice distortion and other microstructures inside the material to fully display a stable characteristic state under the action of the loading force, avoiding inaccurate data due to too short a detection time or other unnecessary interference factors due to too long a time. The peak curve generated by the X-ray diffraction detection data obtained under this standard duration can subsequently accurately calculate the austenite volume content corresponding to the first sample 3 under the loading force according to relevant standards (such as YB / T538-2019 X-ray diffractometer method for quantitative determination of austenite in steel), thereby providing a reliable basis for accurately predicting the phase structure transformation of the target workpiece 1 under special working conditions (such as overspeed test).

[0050] Before step S1 , a continuous cooling transformation curve needs to be measured for the target workpiece 1 .

[0051] Specifically, it is a pre-step to determine the continuous cooling transformation curve (CCT curve) of the target workpiece 1 before step S1. The continuous cooling transformation curve can provide phase change information of the material used in the target workpiece 1 at different cooling rates, including key data such as the phase change start temperature, phase change end temperature, and phase composition. The CCT curve is determined by professional thermal simulation experimental equipment and precise experimental methods. During the experiment, the parameters such as the heating rate, holding time, and cooling rate of the target workpiece 1 material are strictly controlled. For example, the target workpiece is heated to the austenitizing temperature at a specific heating rate, and maintained at this temperature for a certain period of time to fully austenitize the material, and then cooled at different cooling rates. At the same time, advanced detection methods (such as dilatometers, metallographic microscopes, etc.) are used to monitor the volume change, organizational transformation, etc. of the material during the cooling process, so as to draw an accurate CCT curve.

[0052] The significance of determining the CCT curve is that it provides basic data support for subsequent steps. The hardenability of the material can be accurately judged according to the CCT curve, and the following test is carried out when it is determined that the hardenability of the material is good. For example, if the CCT curve of the material shows that its hardenability is good, then when cutting the test circle 2, you can choose a position that can represent the overall material performance to ensure that the structure and performance of the test circle 2 can truly reflect the situation of the target workpiece 1. At the same time, the CCT curve is also helpful in selecting appropriate process parameters in the subsequent heat treatment process (step S2), because it can provide phase change information of the material under different cooling conditions, thereby helping to determine the appropriate cooling rate, holding time and other heat treatment parameters, so that the target workpiece 1 and the test circle 2 can obtain the expected structure and performance.

[0053] The target workpiece 1 includes a cover disk and a shaft disk, or an integrally processed impeller.

[0054] Specifically, the target workpiece 1 includes a structure composed of a cover disc and a shaft disc, as well as an integrally processed impeller structure. For the target workpiece 1 composed of a cover disc and a shaft disc, the cover disc portion has a specific shape and size. For example, the cover disc may be circular, and its diameter is determined according to the actual application scenario and equipment specification requirements. The edge may have a certain thickness gradient or a special contour shape to meet the functional requirements of connection with other components, sealing or fluid guidance. The shaft disc is adapted to the cover disc, and a hole for installing the shaft is provided in the center thereof. The hole diameter is precisely processed to ensure a close fit with the shaft. The surface of the shaft disc may be distributed with structures such as ribs and grooves for enhancing structural strength or realizing specific functions.

[0055] In the form of the target workpiece 1 of the integrally processed impeller, the shape, number, angle and distribution of the impeller blades are carefully designed. The blades can be arc-shaped, twisted or other shapes that conform to the principles of fluid mechanics. The number is determined based on the diameter, rotation speed, required flow rate and pressure of the impeller, and the installation angle is accurately calculated to ensure that the fluid can be efficiently worked at high speed to achieve energy transfer and conversion. Whether it is a cover disc and shaft disc combination or an integrally processed impeller, they are all used as the research object of the method for predicting the phase structure transformation of materials in the present invention. By performing a series of operations such as rough machining, cutting test circles 2, heat treatment, stretching and X-ray diffraction detection, the phase structure transformation characteristics of the material under different working conditions are deeply explored, thereby providing key data support and technical basis for optimizing the manufacturing process of the target workpiece 1 and improving its performance and reliability in practical applications.

[0056] In step S2, when the target workpiece 1 and the test ring 2 are heat treated, a process of conditioning treatment and aging treatment may be adopted, or a process of solid solution treatment, conditioning treatment and aging treatment may be adopted.

[0057] Specifically, two feasible processes are provided for the heat treatment process of the target workpiece 1 and the test circle 2. One is a combination of adjustment treatment and aging treatment process. In the adjustment treatment stage, key parameters such as heating temperature, holding time and cooling rate are precisely controlled. For example, the target workpiece 1 and the test circle 2 are heated to a specific temperature range, which is determined according to the characteristics of the material and the expected performance requirements. Generally, the temperature is kept near the phase change point of the material for a certain period of time to make the internal structure of the material fully homogenized and adjusted, and then an appropriate cooling method is adopted, such as air cooling, oil cooling or wind cooling, to obtain a specific organizational morphology and performance basis. The aging treatment is carried out after the adjustment treatment, and a long-term insulation is carried out at a relatively low temperature to promote the uniform dispersion of the precipitated phase inside the material, further improving the comprehensive properties of the material such as strength, hardness and toughness.

[0058] The second is a process that combines solution treatment with adjustment treatment and aging treatment. During solution treatment, the target workpiece 1 and test circle 2 are heated to a high temperature so that the alloy elements are fully dissolved in the matrix to form a uniform austenite structure. The selection of the heating temperature must take into account the material composition and equipment conditions. The holding time ensures that the alloy elements are fully dissolved, and then the temperature is quickly cooled to inhibit the precipitation of the second phase. A supersaturated solid solution is obtained, laying the foundation for subsequent treatment. Then an adjustment treatment is carried out, which has a similar effect to the above adjustment treatment and further optimizes the organizational morphology. Finally, an aging treatment is carried out to precipitate a dispersed strengthening phase in the supersaturated solid solution, significantly improving the mechanical properties of the material. Through the flexible use of these two process schemes, the organization and performance of the target workpiece 1 can be accurately controlled according to the specific materials, design requirements and actual application scenarios, providing a solid heat treatment quality guarantee for the subsequent study of the material phase organization transformation of the target workpiece 1 under different working conditions through test circle 2.

[0059] Example 1

[0060] The impeller with a diameter of Φ450mm before heat treatment is produced. The material is FV520B steel. The design yield strength requirement is 686-800MPa. The yield strength is measured to be 800Mpa after a tensile test on a universal testing machine, which meets the yield strength requirement. The continuous cooling transformation curve is measured for the target workpiece 1. When cutting the test circle 2, a position that can represent the overall material performance can be selected to ensure that the structure and performance of the test circle 2 can truly reflect the situation of the target workpiece 1. The target workpiece 1 (the cover disk and the shaft disk, or the integrally processed impeller) is rough-machined and the test circle 2 is cut. The target workpiece 1 and the test circle 2 are heat-treated. After the heat treatment, different loading forces are applied to the first sample 3 for stretching, and X-ray diffraction detection is performed on the first sample 3 when different loading forces are applied to form corresponding peak curves;

[0061] The first sample 3 has a gauge thickness of 1 mm and a gauge cross-sectional area of ​​5 mm. Its theoretical yield strength is calculated to be 3430 N. Then, different loading forces are applied to the first sample 3 to pull it up. When different loading forces are applied, X-ray diffraction detection is performed on the first sample 3 to form corresponding peak curves. The loading force ranges from 0 to 3430 N. The tensile forces are maintained at 0 N, 1715 N, 2744 N and 3430 N for 1 minute, and the peak curves are recorded at the same time, such as Figure 4-Figure 6 As shown, the volume content of austenite is calculated according to the X-ray diffractometer method for quantitative determination of austenite in steel YB / T538-2019. It is measured that the austenite content is about 23% when the loading force is 0N, the austenite content is about 22.75% when the loading force is 1715N, the austenite content is about 23.2% when the loading force is 2744N, and the austenite content is about 23% when the loading force is 3430N.

[0062] It can be seen from the volume content of austenite that the first sample 3 does not undergo obvious volume content changes after different tensile forces. Then, after the target workpiece 1 is finely processed, an overspeed test is performed for 1 minute. The target workpiece 1 is the impeller. The test results are as follows:

[0063] Before the impeller overspeed test, the outer diameter φA is 450mm, the mouth diameter φB is 324.98mm, and the inner hole diameter φD is 168.03mm.

[0064] After the impeller overspeed test, the outer diameter φA is 450mm, the mouth diameter φB is 324.98mm, and the inner hole diameter φD is 168.04mm.

[0065] The dimensional deviation of the target workpiece 1 before and after over-rotation is 0mm for the outer diameter, 0% for the deviation; 0mm for the mouth ring diameter, 0% for the deviation; 0.01mm for the inner hole diameter, 0.006% for the deviation, which meets the standard requirements.

[0066] The test results are consistent with the impeller overspeed test results.

[0067] Example 2

[0068] The impeller with a diameter of Φ900mm before heat treatment is produced. The material is 17-4PH steel. The design yield strength requirement is 550-735MPa. The yield strength is measured by a universal testing machine after a tensile test. The measured yield strength is 700Mpa, which meets the yield strength requirement. The continuous cooling transformation curve of the target workpiece 1 is measured. When cutting the test circle 2, a position that can represent the overall material performance can be selected to ensure that the structure and performance of the test circle 2 can truly reflect the situation of the target workpiece 1. The target workpiece 1 (cover disk and shaft disk, or integrally processed impeller) is rough-processed and the test circle 2 is cut. The target workpiece 1 and the test circle 2 are heat-treated. After the heat treatment, different loading forces are applied to the first sample 3 for stretching, and X-ray diffraction detection is performed on the first sample 3 when different loading forces are applied to form corresponding peak curves;

[0069] The first sample 3 has a gauge thickness of 1.2 mm and a gauge cross-sectional area of ​​6 mm. Its theoretical yield strength is calculated to be 3300 N. Then different loading forces are applied to the first sample 3 to pull it up. X-ray diffraction detection is performed on the first sample 3 when different loading forces are applied to form a corresponding peak curve. The loading force ranges from 0 to 2750 N. The tensile force needs to be maintained for 1 minute at 0 N, 1650 N, 2640 N and 3300 N, respectively. The peak curve is recorded at the same time. The austenite volume content is calculated according to the X-ray diffractometer method for quantitative determination of austenite in steel YB / T538-2019. It is measured that the austenite content is about 3.6% when the loading force is 0 N, about 31.8% when the loading force is 1650 N, about 26.1% when the loading force is 2640 N, and about 26% when the loading force is 3300 N.

[0070] It can be seen from the austenite volume content that the austenite volume content of the first sample 3 changes significantly after different tensile forces, indicating that the target workpiece 1 undergoes a structural transformation during the tensile process. Then, after the target workpiece 1 is finely processed, an overspeed test is performed for 1 minute. The target workpiece 1 is the impeller, and the test results are as follows:

[0071] Before the impeller overspeed test, the outer diameter φA is 900mm, the mouth diameter φB is 707.97mm, and the inner hole diameter φD is 300.01mm.

[0072] After the impeller overspeed test, the outer diameter φA is 900.18mm, the mouth diameter φB is 708.19mm, and the inner hole diameter φD is 300.28mm.

[0073] The dimensional deviation of the impeller before and after over-rotation is 0.18mm in outer diameter, with a deviation of 0.02%; the difference in the diameter of the mouth ring is 0.22mm, with a deviation of 0.031%; the difference in the inner hole diameter is 0.27mm, with a deviation of 0.09%. The deviations of the diameter of the mouth ring and the inner hole exceed the standard requirements.

[0074] The test results are consistent with the impeller overspeed test results.

[0075] Example 3

[0076] The impeller with a diameter of Φ450mm before heat treatment is produced. The material is ASTMA705-630 steel. The design yield strength requirement is not less than 900MPa. The yield strength is measured to be 985Mpa after a tensile test on a universal testing machine, which meets the yield strength requirement. The continuous cooling transformation curve is measured for the target workpiece 1. When cutting the test circle 2, a position that can represent the overall material performance can be selected to ensure that the structure and performance of the test circle 2 can truly reflect the situation of the target workpiece 1. The target workpiece 1 (the cover disk and the shaft disk, or the integrally processed impeller) is rough-machined and the test circle 2 is cut. The target workpiece 1 and the test circle 2 are heat-treated. After the heat treatment, different loading forces are applied to the first sample 3 for stretching, and X-ray diffraction detection is performed on the first sample 3 when different loading forces are applied to form corresponding peak curves;

[0077] The first sample 3 has a gauge thickness of 0.8 mm and an area of ​​4 mm. Its theoretical yield strength is calculated to be 3600 N.

[0078] Then, different loading forces are applied to the first sample 3 to pull it up, and X-ray diffraction detection is performed on the first sample 3 when different loading forces are applied to form corresponding peak curves. The loading force ranges from 0 to 3600N, and the tensile force needs to be maintained for 1 minute at 0N, 1800N, 2880N and 3600N, respectively. The peak curve is recorded at the same time, and the austenite volume content is calculated according to the X-ray diffractometer method for quantitative determination of austenite in steel YB / T538-2019. It is measured that the austenite content is about 5.96% when the loading force is 0N, about 6.02% when the loading force is 1800N, about 2.99% when the loading force is 2880N, and about 2.61% when the loading force is 3600N.

[0079] It can be seen from the austenite volume content that the austenite volume content of the first sample 3 does not change significantly at low tensile force, but changes significantly after high tensile force, indicating that the target workpiece 1 undergoes organizational transformation during the high stress tensile process. Then, after the target workpiece 1 is finely machined, the target workpiece 1, i.e., the impeller, is subjected to an overspeed test at 600 MPa and 900 MPa for 1 minute. The test results are as follows:

[0080] Before the impeller overspeed test, the outer diameter φA is 900mm, the mouth diameter φB is 707.97mm, and the inner hole diameter φD is 300.01mm.

[0081] After the 600MPa overspeed test, the outer diameter φA of the impeller is 900.02mm, the mouth diameter φB is 707.97mm, and the inner hole diameter φD is 300.02mm.

[0082] The dimensional deviation of the impeller before and after over-rotation is 0.02mm in outer diameter and 0.002% in deviation; 0mm in mouth diameter and 0% in deviation; 0.01mm in inner hole diameter and 0.003% in deviation, which meets the standard requirements.

[0083] After the overspeed test at 900MPa, the outer diameter φA of the impeller is 900.18mm, the mouth diameter φB is 708.19mm, and the inner hole diameter φD is 300.28mm.

[0084] The dimensional deviation of the impeller before and after over-rotation is 0.18mm in outer diameter, with a deviation of 0.02%; the difference in the diameter of the mouth ring is 0.22mm, with a deviation of 0.031%; the difference in the inner hole diameter is 0.27mm, with a deviation of 0.09%. The deviations of the diameter of the mouth ring and the inner hole exceed the standard requirements.

[0085] The test results are consistent with the impeller overspeed test results.

[0086] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A method for predicting phase structure transformation of impeller material, characterized in that: The following steps are involved: S1, performing rough machining on a target workpiece (1), and cutting a test circle (2) on the target workpiece (1); S2, performing heat treatment on the target workpiece (1) and the test circle (2); S3, cutting a first sample (3) from the test ring (2), applying different loading forces to the first sample (3) to stretch it, and performing X-ray diffraction detection on the first sample (3) when the different loading forces are applied to form corresponding peak curves; S4. Obtain the corresponding austenite volume content when different forces are applied to the first sample (3) through the peak curve.

2. The method for predicting the phase structure transformation of impeller material according to claim 1, characterized in that: Before step S3, it is necessary to cut a second sample from the test ring (2) and perform a tensile test on the second sample to obtain the actual yield strength. When the actual yield strength meets the design yield strength requirement, step S3 is performed.

3. The method for predicting the phase structure transformation of impeller material according to claim 2, characterized in that: In step S3, the tensile loading force is increased from zero to the theoretical yield stress.

4. The method for predicting the phase structure transformation of impeller material according to claim 3, characterized in that: In step S3, the stretching needs to be maintained for 0.5 minutes to 2 minutes when performing X-ray diffraction detection.

5. The method for predicting the phase structure transformation of impeller material according to claim 4, characterized in that: When performing X-ray diffraction detection, the stretching needs to be maintained for 1 minute.

6. The method for predicting the phase structure transformation of impeller material according to claim 5, characterized in that: Before step S1, a continuous cooling transformation curve needs to be measured for the target workpiece (1).

7. The method for predicting the phase structure transformation of impeller material according to claim 6, characterized in that: The target workpiece (1) includes a cover disk and a shaft disk, or an integrally processed impeller.

8. The method for predicting the phase structure transformation of impeller material according to claim 7, characterized in that: In step S2, when the target workpiece (1) and the test ring (2) are subjected to heat treatment, a process of conditioning treatment and aging treatment may be adopted, or a process of solid solution treatment, conditioning treatment and aging treatment may be adopted.

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