A method of reconstructing the orientation of original beta-ti grains before phase transition

Abstract

The application relates to the technical field of metal material development, in particular to a method for reconstructing the orientation of original beta-Ti grains before phase transition, characterized by the following steps: step 1) adopting a {110} hcp polar diagram of a phase transition product to perform orientation reconstruction, four characteristic triangles on the polar diagram are found, that is, four (111) bcc surface polar points of the original beta-Ti grains; step 2) determining the phase transition product area of the same original beta-Ti grain according to the polar diagram, and determining the centers of the four characteristic triangles on the corresponding polar diagram; step 3) measuring the projection coordinates of the four centers to obtain the crystal direction corresponding to each center; and step 4) calculating a [100] and [001] direction matrix, and obtaining the orientation matrix M of the original beta-Ti grain after processing. The application has the beneficial effect that the orientation of the original beta-Ti grain before phase transition is reconstructed, the orientation accuracy of the reconstructed original beta-Ti grain is high, the accuracy requirement in the titanium material production process is fully met, the calculation method is simple, the operation amount is small, and the application range is wide.​

Description

Technical Field

[0001] This invention relates to the field of metallic material development technology, and in particular to a method for reconstructing the orientation of the original β-Ti grains before phase transformation. Background Technology

[0002] Titanium, due to its low density, corrosion resistance, good impact resistance, and high strength, is increasingly widely used in aerospace, oil pipelines, marine applications, and biomedicine. Factors affecting the properties of titanium include not only its macroscopic morphology but also the orientation of its grains. When titanium is cooled from a high temperature to room temperature, it undergoes a β-Ti → α-Ti transformation, preventing the original β-Ti grains from remaining at room temperature. For materials researchers, the state information of the original β-Ti microstructure before the phase transformation, such as the orientation, morphology, size, presence of special types of original β-Ti grains (e.g., β-Ti twins), and the presence of β-Ti texture, all significantly impact the phase transformation process, microstructure, and properties. Studying this influence is virtually impossible before reconstructing the orientation of the original β-Ti grains. Therefore, reconstructing the orientation of the original β-Ti grains before the phase transformation is of great significance. During the transformation from β-Ti to α-Ti, a covariant phase transformation mechanism is followed. The orientation of the phase transformation products formed after the phase transformation cannot be arbitrary, but must maintain a certain orientation relationship with the original β-Ti grains (called orientation relationship). β-Ti has a BCC structure, and α-Ti has an HCP structure. By utilizing this specific orientation relationship, the original β-Ti grains before the phase transformation can be reconstructed.

[0003] Current calculations of the orientation of the parent phase before phase transformation mainly focus on steel materials, with very little research on Ti alloys. Therefore, this patent proposes a novel and more convenient method for reconstructing the orientation of the original β-Ti grains without relying on residual β-Ti microstructure; no related technologies have been publicly reported to date. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reconstructing the orientation of the original β-Ti grains before phase transformation, overcoming the shortcomings of existing technologies, and utilizing the 12 α-Ti variants obtained from the phase transformation of the original β-Ti grains. Crystal orientation with β-Ti The parallel crystal orientation allows these 12 α-Ti variants to be located in {110} hcp Four "characteristic triangles" are formed on the pole figure. By measuring the coordinates of these four poles and performing the corresponding matrix calculations, the β-Ti orientation can be calculated.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for reconstructing the orientation of original β-Ti grains before phase transformation, characterized by the following specific operation steps:

[0007] Step 1) Using the {110} phase transition product hcp The orientation of the original β-Ti grains is reconstructed using pole figures in {110}. hcp Four characteristic triangles were found on the pole figure. The center of these characteristic triangles is the four (111)bcc plane poles of the original β-Ti grain.

[0008] Step 2) Based on {110} hcp Pole diagrams are used to identify phase transformation product regions belonging to the same original β-Ti grain, within the corresponding {110}. hcp The centers of the four characteristic triangles on the pole figure are the {111}bcc poles of the original β-Ti grain;

[0009] Step 3) Measure the projected coordinates of the four centers, then the coordinates of the spherical poles of each center can be obtained as follows: Where P1'(x1,y1) are the coordinates of the corresponding projection point, and the coordinates of P1' can be directly obtained from the pole figure. α and β are the angles between the pole P1 and the y-axis and z-axis, respectively, from which the crystal orientations corresponding to each center can be obtained;

[0010] Step 4) Matrix and The cross product of matrices yields the

[101] direction matrix. The cross product of the matrix and the

[111] matrix can be obtained Direction matrix, then combine

[101] with The cross product is used to calculate a

[010] orientation matrix of the original β-Ti grain. After changing the pairing, the

[100] and

[001] orientation matrices are calculated using the same method. After orthogonalization and normalization, the orientation matrix M of the original β-Ti grain is obtained.

[0011] Furthermore, the orientation reconstruction process does not depend on residual β-Ti structure.

[0012] Furthermore, the phase transition is applicable to all covariant phase transition processes in metallic materials where the orientation relationship is Burgers relationship or near-Burgers relationship.

[0013] Furthermore, the phase change product region includes hot-rolled products, cold-rolled products, heat-treated products, post-weld heat-affected zones, and welds.

[0014] Furthermore, when reconstructing the orientation of the original β-Ti grains, information on the morphology and size of the original β-Ti grains before the phase transformation can be obtained.

[0015] Further, the metal is any one of titanium-based metal, Zr and its alloy or other hexagonal system metal.

[0016] Further, the pole figure processing software is HKL-Channel 5.

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

[0018] 1) The reconstruction of the original beta-Ti grain orientation before phase transition is realized, the accuracy of the reconstructed original beta-Ti grain orientation is high, the accuracy requirement of the reconstruction of the original beta-Ti grain orientation in the titanium material production process is fully met, the calculation method is simple, the operation amount is small, and the application range is wide;

[0019] 2) The reconstruction of the original beta-Ti grain orientation does not depend on the residual beta-Ti structure, and the original beta-Ti grain orientation can still be successfully reconstructed when there is no residual beta-Ti structure;

[0020] 3) It can also be used for deformed structure, and the reconstruction does not need to know the specific orientation relationship. The reconstruction of the original beta-Ti grain orientation does not need to know the orientation relationship, and the orientation relationship does not affect the reconstruction process of the original beta-Ti grain; the use condition is less limited, the method has wide adaptability, and can be used for the orientation reconstruction of the original beta-Ti grain with serious local micro area and variant selection;

[0021] 4) It is suitable for all co-transformation processes; it can be applied to the reconstruction of the original beta-Ti grain orientation of all hot-rolled products, cold-rolled products, heat-treated products, heat-affected zones after welding and welds, and the like; the original beta-Ti grain orientation of the deformed rolling state structure can also be reconstructed by using this method;

[0022] 5) The original beta-Ti grain morphology and size information can also be obtained by using the present application; the method can be used for the co-transformation process of all hexagonal system metal materials. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is the {110} pole figure of the phase transition product when the original beta-Ti grain is oriented and reconstructed in Example 1 of the present application, and four "characteristic triangles" are formed, the centers of the four "characteristic triangles" are the {111} poles of the original beta-Ti grain respectively, and the four {111} poles are measured. hcp bcc γ ​​The pole diagram is used to calculate the next step of the original β-Ti grain orientation. This indicates that the method in the present application can be used to reconstruct the original β-Ti grain orientation and determine the phase transformation product range belonging to the same original β-Ti grain.

[0024] Figure 2 The {110} pole diagram of the phase transformation product of the original β-Ti grain is used in the present application embodiment 1. hcp The ipf diagram of the phase transformation product of the original β-Ti grain is reconstructed by the pole diagram of the original β-Ti grain without deformation.

[0025] Figure 3 The {110} pole diagram of the 12 variants of the phase transformation product calculated by the orientation in Table 1 of the reconstructed original β-Ti grain is used in the present application embodiment 1. hcp The superposition of the theoretical pole diagram and the actual pole diagram can be seen, which indicates that the theoretical pole diagram and the actual pole diagram are in good agreement, which indicates the correctness of the reconstructed original β-Ti grain orientation in Table 1, and further indicates the correctness of the original β-Ti grain orientation reconstruction by the method in the present application without deformation.

[0026] Figure 4 The {110} pole diagram of the phase transformation product of the original β-Ti grain is used in the present application embodiment 2. hcp The ipf diagram of the phase transformation product of the original β-Ti grain is reconstructed by the pole diagram of the original β-Ti grain with deformation.

[0027] Figure 5 The {110} pole diagram of the 12 variants of the phase transformation product calculated by the orientation in Table 1 of the reconstructed original β-Ti grain is used in the present application embodiment 2. hcp The superposition of the theoretical pole diagram and the actual pole diagram can be seen, which indicates that the theoretical pole diagram and the actual pole diagram are in good agreement, which indicates the correctness of the reconstructed original β-Ti grain orientation in Table 1, and further indicates the correctness of the original β-Ti grain orientation reconstruction by the method in the present application with deformation. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, but not all.

[0029] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the accompanying drawings needed in the specific embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other accompanying drawings without creative labor.

[0030] The components of the embodiments of the application described and illustrated herein can be arranged and designed in a wide variety of different configurations. Therefore, the following detailed description of the embodiments of the application, as provided in the accompanying drawings, is not intended to limit the scope of the application, but is merely representative of selected embodiments of the application.

[0031] In the following examples, the experimental titanium material used is forged TC4 titanium alloy, and the specific composition is (mass fraction, %): Al: 5.90, V: 3.98, Fe: 0.07, C: 0.011, N: 0.002, O: 0.051. The sample is processed as follows: a small cylindrical sample of Φ10mm x 15mm is cut from the blank, heated to 1050℃ at a heating rate of 5℃ / s, held for 300s, then cooled to 950℃ at a cooling rate of 5℃ / s, held for 30s, and then deformed at a strain rate of 1s -1 A single-pass compression experiment is performed, with a deformation of 40%, and after deformation, quenching to room temperature. Then, an EBSD sample is cut, and mechanical grinding is performed using 400#, 800#, 1200#, and 2000# sandpaper in sequence, and then micron-level chromium oxide polishing paste is used for mechanical polishing until the surface is bright and scratch-free. Then, electrolytic polishing is performed in a 10% perchloric acid + 90% ethanol solution, with a voltage of 25V and a current of about 0.5mA, for a time of 30-40s. After polishing, EBSD experiments are performed on a Zeiss Ultra 55 field emission scanning electron microscope equipped with an Oxford-EBSD probe, with an acceleration voltage of 20V, a tilt angle of 70°, and a step size of 2um. After scanning, the EBSD data is processed using HKL Channel 5 software.

[0032] Example 1

[0033] A method for reconstructing the orientation of original β-Ti grains before phase transformation, the specific operation steps are as follows: step 1) as shown in Figure 1 , the orientation of original β-Ti grains is reconstructed using the {110} hcp pole figure of the phase transformation product, and four characteristic triangles are found on the {110} hcp pole figure, and the centers of the four characteristic triangles are the four (111) bcc face poles of the original β-Ti grains; step 2) according to the {110} hcp pole figure, the phase transformation product regions belonging to the same original β-Ti grain are determined, and the centers of the four characteristic triangles on the corresponding {110} hcp pole figure are determined, which are the {111} bcc pole points of the original β-Ti grains; step 3) the projection coordinates of the four centers are measured, and the spherical pole coordinates of each center can be obtained as where P1'(x1, y1) is the corresponding projection point coordinate, and the P1' coordinate can be directly obtained from the pole figure, and the coordinate point α and β are the angles of the pole P1 with the y-axis and z-axis, and the crystal direction corresponding to each center can be obtained; step 4) multiplying the matrix with matrix and matrix cross product can obtain the

[101] direction matrix, matrix and

[111] matrix cross product can obtain direction matrix, and then multiplying

[101] with cross product to calculate a

[010] direction matrix of the original β-Ti grain, and after replacement, the

[100] and

[001] direction matrices are calculated by the same method, and after orthogonalization and normalization, the orientation matrix M of the original β-Ti grain is obtained.

[0034] Figure 2 In Example 1, {110} hcp The ipf diagram of the phase transition product of the original β-Ti grain before phase transition obtained by polar reconstruction is shown in Table 1, and the orientation matrix of the original β-Ti grain reconstructed by the method in the application and the orientation expressed by Euler angles are shown in Table 1, Figure 3 The theoretical {110} hcp polar diagram and the actual {110} hcp polar diagram are superimposed, and it can be found that they coincide well, which fully illustrates the correctness of reconstructing the original β-Ti grain before phase transition and its orientation by using this method.

[0035] Example 2

[0036] A method for reconstructing the orientation of the original β-Ti grain before phase transition, the specific operation steps are as follows: step 1) as Figure 1 , the {110} hcp polar diagram of the phase transition product is used to reconstruct the orientation of the original β-Ti grain, and four characteristic triangles are found on the {110} hcp polar diagram, and the centers of these characteristic triangles are the four (111) bcc face poles of the original β-Ti grain; step 2) according to the {110} hcp polar diagram, the phase transition product region belonging to the same original β-Ti grain is determined, and the centers of the four characteristic triangles on the corresponding {110} hcp polar diagram are determined, which are the {111} bcc polar points of the original β-Ti grain; step 3) the projection coordinates of the four centers are measured, and then the spherical polar coordinates of each center can be obtained as Where P1'(x1, y1) is the corresponding projection point coordinate, and the P1' coordinate can be directly obtained from the polar diagram, and the coordinate point α and β are the angles of the pole P1 with the y-axis and z-axis, and the crystal direction corresponding to each center can be obtained

[0037] The crystal direction of the original β-Ti grain; step 4) multiplying the matrix with The matrix and The matrix cross product can obtain the

[101] direction matrix, The matrix and

[111]

[0038] The matrix cross product can obtain The direction matrix, and The cross product calculates a

[010] direction matrix of the original β-Ti grain, and the same method is used to calculate the

[100] and

[001] direction matrices after replacement and matching. After orthogonalization and normalization, the orientation matrix M of the original β-Ti grain is obtained.

[0039] Figure 4 In the embodiment 2, the {110} pole figure of the original β-Ti grain before phase transition is reconstructed by using the method in the embodiment 2. hcp The ipf figure of the phase transition product of the original β-Ti grain before phase transition is reconstructed by using the pole figure, and table 1 shows the orientation matrix of the original β-Ti grain reconstructed by using the method in the embodiment 2 and the orientation expressed by Euler angles, Figure 5 The theoretical {110} pole figure of the 12 variants calculated by using the orientation reconstructed in the embodiment 2, hcp The superposition of the pole figure and the actual pole figure can find that they are well coincided and have high accuracy, which fully shows the correctness of the method for reconstructing the original β-Ti grain before phase transition and the orientation thereof.

[0040] The method successfully reconstructs the orientation of the original β-Ti grain before phase transition, and has high accuracy. Table 1 is the original β-Ti grain orientation reconstructed by using the method in the embodiment 2. Figure 2 and Figure 4 The original β-Ti grain orientation in the embodiment 2. In table 1, the original β-Ti grain orientation in the embodiment 2 is reconstructed by using the {110} hcp Pole figure of the phase transition product, Figure 2 The original β-Ti grain (without deformation) and Figure 4 The original β-Ti grain (with deformation) in the embodiment 2, and the orientation matrixes are The corresponding Euler angles are (23.89°, 85.90°, 151.43°),

[0041] (141.02°, 89.19°, 313.52°).

[0042] Table 1

[0043]

[0044] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A method of reconstructing the original β-Ti grain orientation before phase transformation, characterized by, The specific operation steps are as follows: Step 1) Orientation reconstruction of original β-Ti grains using pole figure of phase transformation product on {110} hcp Step 2) Finding 4 characteristic triangles on {110} hcp pole figure, the center of which is the 4 (111) bcc pole of original β-Ti grains. Step 2) according to {110} hcp polar figure, the center of four characteristic triangles determined on the corresponding {110} hcp polar figure is the {111} bcc pole of the original β-Ti grain; Step 3) The projection coordinates of the four centers are measured, and the spherical polar coordinates of the centers are obtained as where P1'(x1, y1) is the corresponding projection point coordinate, which can be directly obtained from the polar diagram, and the coordinate point α and β are the angles between the polar point P1 and the y-axis and the z-axis, and the corresponding crystal direction of each center is obtained. Step 4) multiply matrix with matrix cross product to get [101] direction matrix, matrix and [111] matrix cross product to get direction matrix, and then multiply [101] with cross product to get a [010] direction matrix of the original β-Ti grain. Replace the combination and use the same method to calculate the [100] and [001] direction matrices. After orthogonalization and normalization, the orientation matrix M of the original β-Ti grain is obtained.

2. A method of re-orienting the original β-Ti grain orientation prior to phase transformation according to claim 1, characterized in that, The orientation reconstruction process is independent of residual beta-Ti structure.

3. The method of reorienting the prior beta-Ti grain orientation of a phase transformation according to claim 1, wherein, The phase transition is adapted to all covariant phase transition processes with Burgers relationship or near Burgers relationship of the site relationship in the metal material.

4. The method of reorienting the prior beta-Ti grain orientation of a phase transformation according to claim 2, wherein, The phase transition product region is a hot-rolled product, a cold-rolled product, a product after heat treatment, a heat-affected zone after welding and a weld.

5. The method of reorienting the prior beta-Ti grain orientation of a phase transformation according to claim 1, wherein, In the orientation reconstruction of the original beta-Ti grain, the information of the original beta-Ti grain morphology and size before phase transition is further obtained.

6. The method of reorienting the prior beta-Ti grain orientation of a phase transformation according to claim 3, wherein, The metal is any one of titanium-based metal, Zr and its alloy or other hexagonal system metal.

7. The method of reorienting the prior beta-Ti grain orientation of a phase transformation according to claim 1, wherein, The processing software of the pole figure is HKL-Channel 5.

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