Method for distinguishing and calibrating 12 alpha-phase variants of Ti65 high-temperature titanium alloy
The method separates and calibrates 12 α phase variants in Ti65 titanium alloy using EBSD and MATLAB, addressing the lack of quantitative analysis in existing methods to control phase transformation texture and improve mechanical properties.
Patent Information
- Application Number
- CN202411342387.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-27
AI Technical Summary
Existing methods fail to distinguish and calibrate the 12 α phase variants of Ti65 high-temperature titanium alloy, limiting quantitative analysis and control of phase transformation texture, which affects mechanical properties.
A method using electron backscatter diffraction (EBSD) technology and MATLAB-based reconstruction algorithms to separate and calibrate the 12 α phase variants by analyzing crystallographic orientation data and applying the Burgers orientation relationship.
Enables quantitative analysis of phase transformation texture and variant selection, facilitating control over the mechanical properties of Ti65 titanium alloy at room temperature.
Smart Images
Figure CN119198816A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for distinguishing and calibrating 12 alpha phase variants of Ti65 high-temperature titanium alloy, belonging to the technical field of titanium alloy phase transformation. Technical Background
[0002] During the cooling process of titanium alloy, when the temperature is lower than the phase transition point, a β→α phase transition will occur. Since the interface between the two phases needs to meet the minimum dislocation energy requirement during the phase transition, the orientation of the sub-phase α phase and the parent phase β phase conforms to the Burgers orientation relationship, that is, {0001}α / / {110}β, <11-20>α / / <111> β. According to the symmetry of the BCC and HCP metal structures, the same orientation of the parent phase β can theoretically precipitate 12 α phases with different orientations during the cooling process. The special phase transformation orientation relationship between the two phases of the titanium alloy may lead to differences in the crystallographic orientation of the near-α-type titanium alloy at room temperature, which in turn has a certain impact on the mechanical properties. Therefore, it is very important to control the precipitation type of the high-temperature β phase and the secondary α phase during the cooling process. On the one hand, if the 12 α phases with different orientations transformed from the β phase during the phase transformation process are uniformly precipitated and the volume fractions are equal, no variant selection occurs in this case, and thus the titanium alloy has no obvious phase transformation texture at room temperature; on the other hand, if one or several α phase variants are preferentially precipitated, the titanium alloy phase transformation will show obvious variant selection phenomenon, resulting in the titanium alloy showing obvious phase transformation texture. The reasons for variant selection generally include the following aspects: (1) elastic strain energy generated during the β→α phase transformation; (2) the influence of the special orientation relationship between adjacent β grains leading to the preferential precipitation of α phase at the grain boundary; (3) the influence of grain defects and dislocation stress fields inside the β grains; (4) the autocatalytic effect caused by the inhomogeneity of local stresses related to the pre-existing α phase laths.
[0003] However, the existing technology can only provide the function of reconstructing the parent phase in titanium alloys. After reconstruction, only the β phase exists, and the separation of different α phases cannot be achieved. There is currently no method that can calibrate the specific variant type, let alone a method to distinguish and calibrate the 12 α phase variants of Ti65 high-temperature titanium alloy, which limits the quantitative analysis and control of phase transformation texture. Summary of the invention
[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to propose a method for distinguishing and calibrating 12 α phase variants for Ti65 high temperature titanium alloy. This method can transform the selection of variants in the Ti65 phase transformation process from qualitative analysis to quantitative analysis, so as to better study the formation causes and tendencies of the phase transformation texture at room temperature, and is conducive to controlling the occurrence of variant selection through regulation, so as to ensure the performance of Ti65 titanium alloy at room temperature. The specific technical scheme is as follows:
[0005] A method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy comprises the following steps:
[0006] Step 1: Use electron backscatter diffraction (EBSD) technology to collect the orientation information of Ti65 alloy at room temperature;
[0007] Step 2: Import the cpr file data obtained in step 1 into the reconstruction algorithm written in MATLAB to calculate the crystallographic orientation data of the parent phase β phase;
[0008] Step 3: Select a single grain in the β phase reconstructed in step 2, and draw the {110} crystal plane and <111> The crystal orientation pole figures were obtained and the equivalent crystal planes and crystal orientation indices were calibrated. Then, the 12 α phase variants were separated using the MTALAB “variant separation” program.
[0009] Step 4: Draw the {0001} crystal plane and <11-20> crystal direction pole figure of the α-phase variant separated in step 3 according to the Euler angle, and then calibrate the variant type according to the Burgers orientation relationship between different variants and the parent phase.
[0010] The specific method for calculating the parent phase β crystallographic data in step 2 is:
[0011] First, define the initial correspondence between the β-phase and α-phase crystallographic coordinate systems and the sample coordinate system: the coordinate system follows the right-hand rule and has the following relationship: X-axis / / [10-10] α / /
[100] β; Y-axis / / [11-20] α / /
[010] β; Z-axis / /
[0001] α / /
[001] β. The orientation information of the parent phase β during the phase transition can be obtained according to the following formula:
[0012]
[0013] Where B is the orientation matrix of the β-phase parent phase, is the subphase orientation matrix, D is the conversion matrix from cubic to hexagonal, is the symmetry operation matrix of the cubic crystal system. The Euler angles of the α phase and the β phase and their corresponding orientation matrices are shown as follows:
[0014]
[0015] Among them, Φ, For the corresponding three Euler angles, [rst] = [hkl] × [uvw]. It should be noted that hexagonal crystals usually use four indices, so the following formula is needed to obtain the orientation matrix:
[0016]
[0017] Finally, through certain mathematical calculations combined with MATLAB program, the crystallographic data of the parent phase β and its corresponding Euler angle information can be obtained.
[0018] Wherein, the step 3 draws the {110} crystal plane and <111> The crystal orientation pole figure and the equivalent crystal plane and crystal orientation index are calibrated. The specific method is as follows:
[0019] There are 6 equivalent crystal plane indices corresponding to {110} in the cubic structure, namely (110), (1-10), (101), (10-1), (011), (0-11). <111> The corresponding equivalent crystal direction indices include 4, namely <111> , <11-1>, <1-11>, <-111>. The initial correspondence between the β phase crystallographic coordinate system and the sample coordinate system is defined as: X axis / /
[100] β; Y axis / /
[010] β; Z axis / /
[001] β, and then the polar projection points of 6 equivalent crystal planes and 4 equivalent crystal directions are calibrated.
[0020] The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy, the preferred scheme is that in step 3, the 12 different α phase variants in the parent phase β grains are separated and reconstructed by using the written MATLAB program and the Mtex toolbox, and the variant separation program is run as follows:
[0021] Import the reconstructed cpr file, read the position point information and select a β grain for calculation.
[0022] grainSelected=parentGrains(parentGrains.findByLocation([x,y]));
[0023] childGrains=job.grainsPrior(job.mergeId==grainSelected.id);
[0024] childGrains=childGrains('Ti-Hex');
[0025] Different variants are separated according to the Burgers orientation relationship between different α phase variants and the parent phase β after phase transition.
[0026] v1grains=childGrains(job.variantId(childGrains.id)==1);
[0027] v2grains=childGrains(job.variantId(childGrains.id)==2);
[0028] v3grains=childGrains(job.variantId(childGrains.id)==3);
[0029] v4grains=childGrains(job.variantId(childGrains.id)==4);
[0030] v5grains=childGrains(job.variantId(childGrains.id)==5);
[0031] v6grains=childGrains(job.variantId(childGrains.id)==6);
[0032] v7grains=childGrains(job.variantId(childGrains.id)==7);
[0033] v8grains=childGrains(job.variantId(childGrains.id)==8);
[0034] v9grains=childGrains(job.variantId(childGrains.id)==9);
[0035] v10grains=childGrains(job.variantId(childGrains.id)==10);
[0036] v11grains=childGrains(job.variantId(childGrains.id)==11);
[0037] v12grains=childGrains(job.variantId(childGrains.id)==12);
[0038] The specific method of step 4 for drawing the corresponding {0001} crystal plane and <11-20> crystal direction pole figure according to the Euler angles of the separated different α phase variants includes:
[0039] There is only one c-axis in the hexagonal crystal system, that is, there is no equivalent crystal plane for the {0001} crystal plane, so no calibration is required. There are three equivalent crystal direction indices corresponding to <11-20>, namely <11-20>, <-12-10>, and <2-1-10>, which define the initial correspondence between the α phase crystallographic coordinate system and the sample coordinate system: X-axis / / [10-10] α; Y-axis / / [11-20] α; Z-axis / /
[0001] α, and then the polar stereographic projection points of the three equivalent crystal directions are calibrated.
[0040] Furthermore, the step 4 calibrates the variant type according to the Burgers orientation relationship between different α-phase variants and the parent phase. The specific operation method is as follows: first, according to the correspondence between the α-phase {0001} crystal plane and the β-phase {110} crystal plane, determine which two variant types may belong to, and finally, according to the correspondence between the α-phase <11-20> crystal direction and the β-phase <111> The correspondence between crystal directions is used to analyze the specific types of variants.
[0041] The present invention has the following advantages or beneficial effects:
[0042] The method of the invention can separate and calibrate the α-phase variants after the parent phase phase transformation of Ti65 titanium alloy, realize the statistical analysis of the volume fractions of different variants, and can be used to analyze the variant selection law in the phase transformation process and the influence on the phase transformation texture formation, which provides an important research idea for the prediction and regulation of the crystal orientation of Ti65 titanium alloy at room temperature.
[0043] The present invention creates a reconstruction and variant separation operation program in the MTALAB software, thereby realizing the function of phase transformation variant separation using orientation data obtained by EBSD at room temperature, which is beneficial to quantitatively analyze the titanium alloy variant selection rules to regulate the type of phase transformation texture. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Figure 1 The separation results of 12 α phase variants after the β grain phase transformation of the parent phase of the forged Ti65 titanium alloy provided in the embodiment of the present invention and the corresponding unit cell schematic diagram;
[0045] Figure 2 The {0001} crystal plane and <11-20> crystal direction of the V5 variant after phase transformation in the forged Ti65 titanium alloy provided in the embodiment of the present invention are different from the {110} crystal plane and <111> Determination of the Burgers orientation relationship of crystal directions. DETAILED DESCRIPTION
[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0047] Embodiment 1:
[0048] This embodiment takes the forged Ti65 titanium alloy as an example to provide a method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy. The specific steps are as follows:
[0049] Step 1: Use electron backscatter diffraction (EBSD) technology (scanning electron microscope + high-precision EBSD probe, using conventional experimental conditions) to collect the orientation information of Ti65 alloy at room temperature and export the corresponding cpr file;
[0050] Step 2: Import the cpr file data obtained in step 1 into the reconstruction algorithm written in MATLAB to calculate the crystallographic orientation data of the parent phase β phase; the specific method includes:
[0051] First, define the initial correspondence between the β-phase and α-phase crystallographic coordinate systems and the sample coordinate system: the coordinate system follows the right-hand rule and has the following relationship: X-axis / / [10-10] α / /
[100] β; Y-axis / / [11-20] α / /
[010] β; Z-axis / /
[0001] α / /
[001] β. The orientation information of the parent phase β during the phase transition can be obtained according to the following formula:
[0052]
[0053] Where B is the orientation matrix of the β-phase parent phase, is the subphase orientation matrix, D is the conversion matrix from cubic to hexagonal, is the symmetry operation matrix of the cubic crystal system. The Euler angles of the α phase and the β phase and their corresponding orientation matrices are shown as follows:
[0054]
[0055] Among them, Φ, For the corresponding three Euler angles, [rst] = [hkl] × [uvw]. It should be noted that hexagonal crystals usually use four indices, so the following formula is needed to obtain the orientation matrix:
[0056]
[0057] Finally, through mathematical calculations combined with MATLAB program, the crystallographic data of the parent phase β and its corresponding Euler angle information can be obtained.
[0058] Step 3: Select a single grain in the β phase reconstructed in step 2, and draw the {110} crystal plane and <111> The crystal orientation pole figure is calibrated with equivalent crystal planes and crystal orientation indices, and then the 12 α phase variants are separated using the MTALAB "variant separation" program written; one or more parent phase β grains can be selected;
[0059] Among them, the {110} crystal plane and <111> The crystal orientation pole figure and the equivalent crystal plane and crystal orientation index are calibrated. The specific method is as follows:
[0060] There are 6 equivalent crystal plane indices corresponding to {110} in the cubic structure, namely (110), (1-10), (101), (10-1), (011), (0-11). <111> The corresponding equivalent crystal direction indices include 4, namely <111> , <11-1>, <1-11>, <-111>. The initial correspondence between the β phase crystallographic coordinate system and the sample coordinate system is defined as: X axis / /
[100] β; Y axis / /
[010] β; Z axis / /
[001] β, and then the polar projection points of 6 equivalent crystal planes and 4 equivalent crystal directions are calibrated.
[0061] The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy, the preferred scheme is that in step 3, the 12 different α phase variants in the parent phase β grains are separated and reconstructed by using the written MATLAB program and the Mtex toolbox, and the variant separation program is run as follows:
[0062] Import the reconstructed cpr file, read the position point information and select a β grain for calculation.
[0063] grainSelected=parentGrains(parentGrains.findByLocation([x,y]));
[0064] childGrains=job.grainsPrior(job.mergeId==grainSelected.id);
[0065] childGrains=childGrains('Ti-Hex');
[0066] Separate different variants according to the Burgers orientation relationship between different α-phase variants and the parent β-phase after phase transformation.
[0067] v1grains = childGrains(job.variantId(childGrains.id) == 1);
[0068] v2grains = childGrains(job.variantId(childGrains.id) == 2);
[0069] v3grains = childGrains(job.variantId(childGrains.id) == 3);
[0070] v4grains = childGrains(job.variantId(childGrains.id) == 4);
[0071] v5grains = childGrains(job.variantId(childGrains.id) == 5);
[0072] v6grains = childGrains(job.variantId(childGrains.id) == 6);
[0073] v7grains = childGrains(job.variantId(childGrains.id) == 7);
[0074] v8grains = childGrains(job.variantId(childGrains.id) == 8);
[0075] v9grains = childGrains(job.variantId(childGrains.id) == 9);
[0076] v10grains = childGrains(job.variantId(childGrains.id) == 10);
[0077] v11grains = childGrains(job.variantId(childGrains.id) == 11);
[0078] v12grains=childGrains(job.variantId(childGrains.id)==12).
[0079] Step 4: Draw the {0001} crystal plane and <11-20> crystal direction pole figure based on the Euler angle of the α phase variant separated in step 3, and then calibrate the variant type according to the Burgers orientation relationship between different variants and the parent phase. The orientation relationship between 12 different α phase variants and the parent phase is shown in the following table. Among them, the drawing is based on the polar projection of the crystal coordinates, and the calibration is obtained according to the following table.
[0080]
[0081] The specific method of drawing the corresponding {0001} crystal plane and <11-20> crystal direction pole figure according to the Euler angles of the separated different α phase variants specifically includes:
[0082] There is only one c-axis in the hexagonal crystal system, that is, there is no equivalent crystal plane for the {0001} crystal plane, so no calibration is required. There are three equivalent crystal direction indices corresponding to <11-20>, namely <11-20>, <-12-10>, and <2-1-10>, which define the initial correspondence between the α phase crystallographic coordinate system and the sample coordinate system: X-axis / / [10-10] α; Y-axis / / [11-20] α; Z-axis / /
[0001] α, and then the polar stereographic projection points of the three equivalent crystal directions are calibrated.
[0083] Furthermore, the variant type is calibrated according to the Burgers orientation relationship between different α-phase variants and the parent phase. The specific operation method is as follows: first, according to the correspondence between the α-phase {0001} crystal plane and the β-phase {110} crystal plane, it is determined which two variant types may belong to. Finally, according to the correspondence between the α-phase <11-20> crystal direction and the β-phase <111> The correspondence between crystal directions is used to analyze the specific types of variants.
[0084] See attached Figure 1 and Figure 2 , Figure 1 The results of separation of 12 α phase variants after the phase transformation of the parent phase β grains of forged Ti65 titanium alloy and the corresponding unit cell schematic diagram are shown, where (a) is the high-temperature parent phase crystallographic orientation distribution diagram reconstructed based on the Ti65 experimental EBSD data, (b) is the orientation distribution diagram of the α phase of a selected complete β grain, and Figures (V1)-(V12) represent the results of the 12 different separated α phase variants. Figure 2 The {0001} and <11-20> directions of the V5 variant after phase transformation are shown to be different from the {110} and <11-20> directions of the parent phase. <111> The specific Burgers orientation relationship of the crystal direction, Figure 2Figure (d) is the orientation imaging of variant V5, and Figure (e) is the calibration result of the {110} equivalent crystal plane index of the parent β phase and <111> The calibration results of equivalent crystal plane indices. Figure (f) is a schematic diagram of the unit cell of the V5 variant, and Figure (g) is the calibration results of the {0001} crystal plane and the <11-20> equivalent crystal direction of the V5 variant.
[0085] In this Example 1, based on the experimentally obtained room temperature Ti65 titanium alloy orientation data and the reconstruction algorithm, the parent phase crystallographic orientation information was obtained. The 12 α phase variants in the parent phase β grains were separated by programming using MATLAB software and the Mtex toolbox. The {0001} crystal plane and <11-20> crystal direction pole position corresponding to each α phase variant and the {110} crystal plane and <11-20> crystal direction pole position of the original β grain were plotted. <111> The crystal direction pole position, combined with the Burgers orientation relationship during the phase transformation of titanium alloy, finally calibrated the orientation relationship between 12 α phase variants and the parent phase. This method can separate and calibrate the α phase variants after the phase transformation of Ti65 titanium alloy parent phase, realize the statistical analysis of the volume fraction of different variants, and can be used to analyze the variant selection law during the phase transformation process and the influence on the formation of phase transformation texture, which provides an important research idea for the prediction and regulation of the crystal orientation of Ti65 titanium alloy at room temperature.
[0086] Finally, it should be noted that the above embodiments are only for illustrating the technical concept and method of the present invention, rather than limiting the technical solution. Ordinary technicians in this field should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.
Claims
1. A method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy, characterized in that: The following steps are involved: Step 1: Use electron backscatter diffraction (EBSD) technology to collect the orientation information of Ti65 alloy at room temperature; Step 2: Import the cpr file data obtained in step 1 into the reconstruction algorithm written in MATLAB to calculate the crystallographic orientation data of the parent phase β phase; Step 3: Select a single grain in the β phase reconstructed in step 2, and draw the {110} crystal plane and <111> The crystal orientation pole figure was obtained and the equivalent crystal plane and crystal orientation index were calibrated. Then, the 12 α phase variants were separated using the MTALAB "variant separation" program. Step 4: Draw the {0001} crystal plane and <11-20> crystal direction pole figure of the α-phase variant separated in step 3 according to the Euler angle, and then calibrate the variant type according to the Burgers orientation relationship between different variants and the parent phase.
2. The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy according to claim 1 is characterized in that: The method of reconstructing the parent β phase crystallographic orientation data in step 2 specifically includes: First, define the initial correspondence between the β-phase and α-phase crystallographic coordinate systems and the sample coordinate system: the coordinate system follows the right-hand rule and has the following relationship: X-axis / / [10-10] α / / [100] β; Y-axis / / [11-20] α / / [010] β; Z-axis / / [0001] α / / [001] β; the orientation information of the parent phase β during the phase transition process is obtained according to the following formula: Where B is the orientation matrix of the β phase, is the subphase orientation matrix, D is the conversion matrix from cubic to hexagonal, is the symmetry operation matrix of the cubic crystal system; The Euler angles of the α phase and the β phase and their corresponding orientation matrices are shown as follows: In the formula For the corresponding three Euler angles, [rst] = [hkl] × [uvw]; it should be noted that hexagonal crystals usually use four indices, so the orientation matrix needs to be obtained using the following formula: Finally, through mathematical calculations combined with MATLAB program, the crystallographic data of the parent phase β and its corresponding Euler angle information can be obtained.
3. The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy according to claim 1 is characterized in that: The step 3 draws the {110} crystal plane and <111> The crystal orientation pole figure is used to calibrate the equivalent crystal plane and crystal orientation index. The equivalent crystal plane index corresponding to {110} includes 6, namely (110), (1-10), (101), (10-1), (011), and (0-11). <111> The corresponding equivalent crystal direction indices include 4, namely <111> , <11-1>, <1-11>, <-111>; define the initial correspondence between the β phase crystallographic coordinate system and the sample coordinate system, X axis / / [100] β; Y axis / / [010] β; Z axis / / [001] β, and then calibrate the polar stereographic projection points of 6 equivalent crystal planes and 4 equivalent crystal directions.
4. The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy according to claim 1 is characterized in that: In the step three, the 12 different α phase variants in the parent phase β grains are separated and reconstructed using the written MATLAB program and the Mtex toolbox.
5. The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy according to claim 1, characterized in that: In the fourth step, the corresponding {0001} crystal plane and <11-20> crystal direction pole figures are drawn according to the Euler angles of the different α-phase variants separated, and then the variant types are calibrated according to the Burgers orientation relationship between the different variants and the parent phase. The hexagonal crystal system has only one c-axis, that is, there is no equivalent crystal plane for the {0001} crystal plane, so no calibration is required; the equivalent crystal direction index corresponding to <11-20> includes 3, namely <11-20>, <-12-10>, and <2-1-10>, which define the initial correspondence between the α-phase crystallographic coordinate system and the sample coordinate system, X-axis / / [10-10] α; Y-axis / / [11-20] α; Z-axis / / [0001] α, and then the polar projection plane projection points of the three equivalent crystal directions are calibrated.
6. The method for distinguishing and calibrating 12 α phase variants of Ti65 high temperature titanium alloy according to claim 1, characterized in that: The fourth step is to calibrate the variant type according to the Burgers orientation relationship between different α-phase variants and the parent phase. The specific operation method is as follows: first, according to the corresponding relationship between the α-phase {0001} crystal plane and the β-phase {110} crystal plane, determine which two variant types may be, and finally, according to the corresponding relationship between the α-phase <11-20> crystal direction and the β-phase <111> The correspondence between crystal directions is used to analyze the specific types of variants.