Metallographic sample preparation method for adjacent vertex angle and adjacent boundary of titanium alloy sample

Abstract

The invention discloses a metallographic sample preparation method for an adjacent surface vertex angle and an adjacent surface boundary of a titanium alloy sample, and relates to the field of titanium alloy metallographic sample preparation, a cuboid titanium alloy sample is used, and the metallographic sample preparation method comprises the following steps: S1, coating a protective sleeve on the titanium alloy sample, and only exposing an exposed surface needing to be processed; s2, inlaying is conducted, specifically, an epoxy resin type cold inlaying agent with the exothermic peak temperature not larger than 40 DEG C is adopted for conducting cold inlaying on the titanium alloy sample coated with the protective sleeve, and the inlaying position is the position coated with the protective sleeve; s3, grinding and polishing the exposed surface; s4, removing the sample and the protective sleeve, and taking out the titanium alloy sample; s5, the steps S1 to S5 are repeated, and machining of the three exposed faces adjacent in pairs is completed; and S6, corrosion is conducted, specifically, the exposed surface after polishing is corroded through a corrosive agent, then cleaning and blow-drying are conducted, and the metallographic sample is obtained. According to the invention, the metallographic structure sample of the same crystal grain at the adjacent vertex angle and the adjacent boundary of the three adjacent surfaces can be prepared, so that the picture definition and purity of the metallographic structure are high.

Description

Technical Field

[0001] The present invention relates to the field of metallographic sample preparation of titanium alloys, and in particular to a method for metallographic sample preparation of the adjacent surface apex angle and adjacent surface boundary of a titanium alloy sample. Background Art

[0002] Titanium alloys have the advantages of high strength, low density, good toughness and corrosion resistance, and good mechanical properties. Titanium alloys are widely used in aircraft engine and compressor components, rocket and aircraft structural components, and are also used as electrodes in the electrolysis industry, condensers and heaters in the chemical industry, etc. Although, in different application fields, the models and properties of titanium alloys are different, because the microstructure of titanium alloys is closely related to their macroscopic properties, therefore, in the actual use process, it is usually necessary to observe the metallographic structure of titanium alloys.

[0003] Since some titanium alloys (such as TC4, TC17, etc.) are relatively hard, generally, the process of sample embedding - mechanical grinding - mechanical polishing (or manual polishing) - corrosion is used to prepare titanium alloy metallographic samples, so as to obtain a titanium alloy metallographic sample with one test surface being flat and bright. For example, Chinese Patent No. CN115342910A discloses "A Method for Preparing Metallographic Samples of High-Strength Titanium Alloys", which can only make titanium alloy metallographic samples with one test surface. However, in special cases, it is necessary to test the metallographic structure of the same grain at the adjacent surface apex angle of three adjacent surfaces or the adjacent surface boundary of two adjacent surfaces of the same titanium alloy sample. If the conventional process of sample embedding - mechanical grinding - mechanical polishing (or manual polishing) - corrosion is used to prepare titanium alloy metallographic samples, the following problems are likely to occur: (1) Residuals of the embedding agent adhere to the vicinity of the apex angle of three adjacent surfaces and the adjacent surface boundary of two adjacent surfaces of the sample, affecting the corrosion effect and the clarity and purity of the metallographic photos; (2) Scratches appear in the vicinity of the apex angle of three adjacent surfaces and the adjacent surface boundary of two adjacent surfaces of the sample, affecting the clarity and purity of the metallographic photos; (3) The vicinity of the apex angle of three adjacent surfaces and the adjacent surface boundary of two adjacent surfaces of the sample are not flat and bright, affecting the clarity of the metallographic photos.

[0004] Therefore, a solution is needed that can prepare metallographic sample tissues of the same grain at the adjacent surface apex angle of three adjacent surfaces and the adjacent surface boundary of two adjacent surfaces. Summary of the Invention

[0005] The purpose of the present invention is to: in view of the above problems, provide a method for metallographic sample preparation of the adjacent surface apex angle and adjacent surface boundary of a titanium alloy sample, which can prepare metallographic sample tissues of the same grain at the adjacent surface apex angle of three adjacent surfaces and the adjacent surface boundary of two adjacent surfaces, so that the clarity and purity of the metallographic tissue photos are high.

[0006] The technical solution adopted by the present invention is as follows: A metallographic sample preparation method for the adjacent surface apex angle and adjacent surface boundary of a titanium alloy sample. A cuboid titanium alloy sample is used, and the method includes the following steps:

[0007] S1: Wrap a protective sleeve on the titanium alloy sample, and only expose the exposed surface that needs to be processed;

[0008] S2: Inlay. Use an epoxy resin type cold inlaying agent with an exothermic peak temperature not greater than 40 °C to perform cold inlaying on the titanium alloy sample wrapped with the protective sleeve, and the inlaying position is the position where the protective sleeve is wrapped;

[0009] S3: Grind and polish the exposed surface;

[0010] S4: Demold and remove the protective sleeve, and take out the titanium alloy sample;

[0011] S5: Repeat steps S1 - S5 to complete the processing of three pairwise adjacent exposed surfaces;

[0012] S6: Corrode. Use a corrosion agent to corrode the polished exposed surface, then wash and dry it to obtain a metallographic sample.

[0013] Further, the cuboid is a cube, so that the parameters of each surface of the sample are the same, avoiding the influence of size.

[0014] Further, in step S1, the material of the protective sleeve is silica gel.

[0015] Further, the size of the protective sleeve is smaller than the size of the titanium alloy sample, and the elastic deformation of the protective sleeve is used to improve its stability when wrapped on the titanium alloy sample.

[0016] Further, in step S3, grinding is carried out first and then polishing.

[0017] Further, the grinding process is to mechanically grind the exposed surface successively with 120#, 320#, 600#, 1000#, and 1200# silicon carbide sandpapers.

[0018] Further, when polishing, the polished exposed surface is mechanically polished successively with diamond polishing fluids with particle sizes of 1 μm and 0.3 μm.

[0019] Further, in step S4, the demolding method is to complete demolding by means of crushing.

[0020] Further, in step S6, the cleaning process is carried out with anhydrous ethanol.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] 1. In the method disclosed by the present invention, since an epoxy resin type cold inlaying agent with an exothermic peak temperature not greater than 40°C and a silica gel material protective sleeve are combined to fix the metallographic sample, chemical reactions between other cold inlaying agents with higher exothermic peak temperatures and the protective sleeve are solved, dissolution of the protective sleeve is avoided, the protection function of the protective sleeve is ensured to be stable, thereby realizing the protection of the already mechanically polished exposed surface, avoiding the appearance of scratch problems, and also avoiding the attachment of residues of the inlaying agent;

[0023] 2. In the method disclosed by the present invention, due to the existence of the protective sleeve, each test surface can be polished by mechanical polishing, avoiding the uneven brightness at the boundary of adjacent surfaces caused by manual polishing, thereby improving the clarity and purity of the metallographic structure photo;

[0024] 3. The method disclosed by the present invention can prepare a metallographic structure sample of the adjacent surface apex angle of three adjacent surfaces and the same grain at the adjacent surface boundary of two adjacent surfaces, making the clarity and purity of the metallographic structure photo high. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described by way of examples with reference to the accompanying drawings, where:

[0026] Figure 1 is the metallographic sample prepared in the embodiment of the present invention;

[0027] Figure 2 is the metallographic structure image at the boundary of surface A in the metallographic sample prepared in the embodiment of the present invention;

[0028] Figure 3 is the metallographic structure image at the boundary of surface B in the metallographic sample prepared in the embodiment of the present invention;

[0029] Figure 4 is the metallographic structure image at the boundary of surface C in the metallographic sample prepared in the embodiment of the present invention;

[0030] Figure 5 is the metallographic sample prepared in the comparative example;

[0031] Figure 6 is the metallographic structure image at the boundary of surface A' in the metallographic sample prepared in the comparative example;

[0032] Figure 7 is the metallographic structure image at the boundary of surface B' in the metallographic sample prepared in the comparative example;

[0033] Figure 8 is the metallographic structure image at the boundary of surface C' in the metallographic sample prepared in the comparative example; DETAILED DESCRIPTION OF THE INVENTION

[0034] An embodiment is proposed, specifically a metallographic sample preparation method for the adjacent surface apex angle and adjacent surface boundary of a titanium alloy sample. A titanium alloy sample in the shape of a cube with a side length of 10 cm is used. The titanium alloy sample is TC17 titanium alloy, and its metallographic structure is a basket weave structure. The method includes the following steps:

[0035] S1: Wrap a protective sleeve on the titanium alloy sample, and only expose the surface to be processed. The protective sleeve is a square silicone protective sleeve with a side length of 9 mm and a thickness of 0.5 mm. It can be known that the size of the protective sleeve is smaller than that of the titanium alloy sample. The main purpose is to make it have high wrapping stability after wrapping on the titanium alloy sample through the elastic deformation of the silicone.

[0036] S2: Inlay. Use an epoxy resin type cold inlaying agent with an exothermic peak temperature not greater than 40 °C to perform cold inlaying on the titanium alloy sample wrapped with the protective sleeve, and the inlaying position is the position wrapped with the protective sleeve.

[0037] S3: Grind and polish the exposed surface in sequence. The grinding process is to mechanically grind the exposed surface with 120#, 320#, 600#, 1000#, and 1200# silicon carbide sandpapers in sequence. When polishing, mechanically polish the ground exposed surface with diamond polishing fluids with particle sizes of 1 μm and 0.3 μm in sequence.

[0038] S4: Demold the sample and remove the protective sleeve, and take out the titanium alloy sample. When demolding, directly break the epoxy resin type cold inlaying agent by knocking and remove the protective sleeve.

[0039] S5: Repeat steps S1 - S5 to complete the processing of three pairwise adjacent exposed surfaces A, B, and C in sequence.

[0040] S6: Corrode. Use a corrosion agent to corrode the polished exposed surface, then clean it with anhydrous ethanol and dry it to obtain a metallographic sample.

[0041] It should be noted that in this embodiment, the formula of the corrosion agent is known to those skilled in the art, and the corrosion method of looking down at the exposed surface with the corrosion agent is also known to those skilled in the art. For example, the Chinese patent with the publication number CN115342910A discloses "A Method for Preparing Metallographic Samples of High-Strength Titanium Alloys". Therefore, it will not be described in detail in this specification.

[0042] Furthermore, in order to highlight the advantages of this method, a comparative example is proposed in this specification. The method for preparing metallographic samples in the comparative example is the method mentioned in the background technology, which is specifically as follows.

[0043] The titanium alloy sample used is a titanium alloy sample in the shape of a cube with a side length of 10 cm. The titanium alloy sample is TC17 titanium alloy, and its metallographic structure is a basket weave structure. The specific steps are as follows:

[0044] A1: An acrylic cold mounting agent with a conventional exothermic peak temperature higher than 40°C is used. No protective sleeve is used, and only the exposed surface of the line to be processed is exposed.

[0045] A2: After embedding, the exposed surface is mechanically polished successively with 120#, 320#, 600#, 1000#, and 1200# silicon carbide metallographic sandpaper.

[0046] A3: The acrylic cold mounting agent is broken, and the titanium alloy sample is taken out.

[0047] A4: Steps A1 - A3 are repeated to complete the mechanical polishing of the three pairwise adjacent exposed surfaces of A', B', and C'.

[0048] A5: The three exposed surfaces A', B', and C' of the titanium alloy sample are respectively subjected to manual polishing treatment, that is, diamond polishing fluids with particle sizes of 1μm and 0.3μm are used successively, and the three exposed surfaces A', B', and C' of the sample after mechanical polishing are manually polished respectively by hand.

[0049] A6: After polishing, corrosion is carried out. The same corrosion agent as in the embodiment is used, and the same corrosion method and corrosion time are used to corrode the three exposed surfaces A', B', and C' respectively; after corrosion, it is cleaned with anhydrous ethanol and dried to complete the preparation of the metallographic sample of the comparative example.

[0050] The metallographic samples obtained in the embodiment and the comparative example are respectively observed with an optical microscope to observe the metallographic structure of the adjacent surface apex angle and the same grain at the adjacent surface boundary of the three adjacent surfaces. The observation image of the embodiment is as Figures 1 - 4 ; the observation image of the comparative example is as Figures 5 - 8 ; by comparing the images between the two, it can be determined that the clarity and purity of the metallographic structure of the adjacent surface apex angle and the adjacent surface boundary of the three adjacent surfaces in the metallographic sample of the embodiment are higher, and there are no phenomena of cold mounting agent adhesion, scratches, and unevenness.

[0051] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. A metallographic sample preparation method for the adjacent surface apex angle and adjacent surface boundary of a titanium alloy sample, using a cuboid titanium alloy sample, characterized in that: It includes the following steps: S1: Cover a protective sleeve on the titanium alloy sample, and only expose the exposed surface to be processed; S2: Inlay. Use an epoxy resin type cold inlaying agent with an exothermic peak temperature not greater than 40 °C to perform cold inlaying on the titanium alloy sample covered with the protective sleeve, and the inlaying position is the position covered with the protective sleeve; S3: Grind and polish the exposed surface; S4: Remove the inlay and the protective sleeve from the sample, and take out the titanium alloy sample; S5: Repeat steps S1 - S5 to complete the processing of three mutually adjacent exposed surfaces; S6: Corrode. Use a corrosive agent to corrode the polished exposed surface, then clean and dry it to obtain a metallographic sample.

2. The metallographic sample preparation method according to claim 1, characterized in that: The cuboid is a cube.

3. The metallographic sample preparation method according to claim 1, characterized in that: In step S1, the material of the protective sleeve is silica gel.

4. The metallographic sample preparation method according to claim 3, characterized in that: The size of the protective sleeve is smaller than the size of the titanium alloy sample.

5. The metallographic sample preparation method according to claim 1, characterized in that: In step S3, grinding is carried out first and then polishing.

6. The metallographic sample preparation method according to claim 5, characterized in that: The grinding process is to mechanically grind the exposed surface successively with 120#, 320#, 600#, 1000#, and 1200# silicon carbide sandpapers.

7. The metallographic sample preparation method according to claim 5, characterized in that: When polishing, mechanically polish the ground exposed surface successively with diamond polishing fluids with particle sizes of 1μm and 0.3μm.

8. The metallographic sample preparation method according to claim 1, characterized in that: In step S4, the inlay removal method is to complete the inlay removal by crushing.

9. The metallographic sample preparation method according to claim 1, characterized in that: In step S6, the cleaning process is carried out with absolute ethanol.

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