Metallographic sample preparation method of titanium alloy

Abstract

The invention discloses a metallographic sample preparation method of titanium alloy. The metallographic sample preparation method comprises the following steps: providing a titanium alloy sample; mechanically grinding the titanium alloy sample to obtain a mechanically ground titanium alloy sample; after the titanium alloy sample subjected to mechanical grinding is subjected to mechanical polishing through a chemical polishing agent, the pH is adjusted to 7-7.3 through a pH adjusting agent, cleaning and drying are conducted in sequence, and the titanium alloy sample subjected to polishing treatment is obtained; and corroding the polished titanium alloy sample by adopting a metallographic corrosive agent to obtain the titanium alloy metallographic sample. According to the method, black spot defects and dirt generated during conventional mechanical polishing of the titanium alloy can be overcome, the mirror surface smoothness effect is achieved, laboratory operation is simple, the display effect of a corroded metallographic structure is good, and the problem that the polishing cleanliness is poor in the titanium alloy metallographic preparation process is solved.

Description

Technical Field

[0001] The invention relates to the fields of materials and metallurgy, and more specifically to a metallographic sample preparation method for a titanium alloy. Background Art

[0002] With the development of science and technology, the research and development technology of titanium alloys has become increasingly mature. Due to its high specific strength, good corrosion resistance, excellent biocompatibility, etc., titanium alloys are called modern metals and are widely used in various fields such as aerospace, military equipment, petrochemicals, and biomedicine.

[0003] However, in the process of titanium alloy research and development, the metallographic preparation of samples is more difficult than that of steel materials. Specific suspended polishing liquid is often used for polishing, and there are shortcomings such as poor polishing quality, many scratches, and low surface cleanliness. The black spots and dirt on the surface caused by the residual suspended liquid will seriously affect the subsequent evaluation and analysis of the metallographic structure. At present, the polishing methods of titanium alloys can be divided into mechanical polishing, chemical polishing, electrolytic polishing, etc. Among them, mechanical polishing is the most common and easy to operate, but the surface quality is poor; chemical polishing often uses hydrofluoric acid solution to react chemically with the sample for polishing, but hydrofluoric acid is highly toxic and has a high risk factor; the polishing quality of electrolytic polishing will be affected by the electrolysis parameters, and the operation is relatively complicated, which is not suitable for the metallographic preparation of batch samples.

[0004] The Chinese patent with application number 2021111818502 discloses a polishing liquid for polishing titanium alloys, its preparation method and application. The polishing liquid is composed of a variety of magnetic and non-magnetic particles, the formula is cumbersome, and the polishing process is complicated. The Chinese patent with application number 2024103047836 discloses a titanium alloy polishing liquid and a polishing method. The raw material used is a biological extract, which is not a common chemical drug and is not suitable for bulk purchase in the laboratory. When using it, the polishing liquid needs to be properly heated, which adds a process. The Chinese patent with application number 2021108583906 discloses a process for preparing a porous structure on the surface of TC4 titanium alloy by electrochemical dealloying. However, the applicability of this method to the polishing of other titanium alloys is still unclear, and the electrolyte is highly corrosive and harmful to the human body. The Chinese document "Laser-chemical composite polishing and surface morphology evolution of medical TC4 titanium alloy" proposes a new laser-chemical composite surface treatment method, but the process is still in the development stage, and the cost of laser treatment is relatively high. The Chinese document "Experimental Study on Electrochemical Mechanical Polishing of TB2 Titanium Alloy" proposed a polishing technology for TB2 titanium alloy, which adopts a combined electrochemical and mechanical polishing method. However, the combined polishing process has many control parameters, and the polishing effect is greatly affected by the parameters, so the combined operation efficiency is low. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and provide a metallographic sample preparation method for titanium alloy, which can solve the black spot defects and dirt generated during conventional mechanical polishing of titanium alloy, achieve a mirror-like smooth effect, and has simple laboratory operation and good metallographic structure display effect after corrosion, thus solving the problem of poor polishing cleanliness in the metallographic preparation process of titanium alloy.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A method for metallographic sample preparation of titanium alloy comprises the following steps:

[0008] Provide titanium alloy specimens;

[0009] Mechanically grinding the titanium alloy sample to obtain a mechanically ground titanium alloy sample;

[0010] The titanium alloy sample after mechanical grinding is mechanically polished by using a chemical polishing agent, and the pH is adjusted to 7 to 7.3 by using a pH adjusting agent, and then the sample is cleaned and dried in sequence to obtain a polished titanium alloy sample;

[0011] The polished titanium alloy sample is corroded by using a metallographic corrosive agent to obtain a titanium alloy metallographic sample.

[0012] Optionally, the chemical polishing agent includes a polishing agent and an oxidizing agent.

[0013] Optionally, the polishing agent is OPS silicon oxide suspension.

[0014] Optionally, the oxidant comprises a cresol soap solution with a concentration of 1% to 5%.

[0015] Optionally, the volume ratio of the OPS silicon oxide suspension to the cresol soap solution is (50-60):(4-8).

[0016] Optionally, the particle size of silicon oxide in the OPS silicon oxide suspension is 50 nm to 0.05 μm.

[0017] Optionally, the pH of the chemical polishing agent is 8 to 9.5.

[0018] Optionally, the mechanical grinding uses sandpaper with a roughness of 120 mesh to 2000 mesh.

[0019] Optionally, when the roughness of the sandpaper is less than 800 mesh, the grinding pressure of the mechanical grinding is 20N to 30N, the grinding speed of the mechanical grinding is 150rpm to 250rpm, and the grinding time of the mechanical grinding is 5min to 6.5min; when the roughness of the sandpaper is ≥800 mesh, the grinding pressure of the mechanical grinding is 5N to 15N, the grinding speed of the mechanical grinding is 100rpm to 150rpm, and the grinding time of the mechanical grinding is 3.5min to 5min.

[0020] Optionally, the polishing machine pressure of the mechanical polishing is 15N-20N, the polishing speed of the mechanical polishing is 150rpm-200rpm, the polishing time of the mechanical polishing is 6min-10min, and the polishing liquid flow rate of the mechanical polishing is 20ml / min-25ml / min.

[0021] Optionally, the pH regulator is a 10% oxalic acid solution.

[0022] Optionally, the metallographic etching agent includes hydrofluoric acid, nitric acid and water in a volume ratio of 10:25:35.

[0023] Implementing the embodiments of the present invention will have the following beneficial effects:

[0024] (1) The laboratory operation of the present invention is simple and efficient. The formula of the polishing agent, oxidant, and pH adjuster is simple and easy to purchase. After preparation, they can be stored and used for a long time. The preparation and operation of the present invention cause little harm to the health of the experimenter.

[0025] (2) After polishing, the titanium alloy of the present invention has no black spot defects and dirt, no scratches, and can achieve a mirror-like smooth effect. After corrosion, the metallographic cleanliness is high and the display effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a metallographic display of the titanium alloy sample after polishing in Example 1 of the present invention.

[0027] Figure 2 This is a metallographic display of the titanium alloy sample after corrosion in Example 1 of the present invention.

[0028] Figure 3 This is a metallographic display of the titanium alloy sample after polishing in Comparative Example 5 of the present invention.

[0029] Figure 4 This is a metallographic display of the titanium alloy sample after polishing in Comparative Example 6 of the present invention.

[0030] Figure 5 This is a metallographic display of the titanium alloy sample after polishing in Comparative Example 7 of the present invention.

[0031] Figure 6 This is a metallographic display of the titanium alloy sample after corrosion in Comparative Example 7 of the present invention.

[0032] Figure 7 This is a metallographic display of the titanium alloy sample after polishing in Comparative Example 8 of the present invention.

[0033] Figure 8 This is a metallographic display of the titanium alloy sample after corrosion in Comparative Example 8 of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

[0035] Embodiment 1:

[0036] The metallographic sample preparation method of the titanium alloy of this embodiment specifically comprises the following steps:

[0037] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 25N, the grinding speed to 200rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 10N, the grinding speed to 150rpm, and the grinding time to 4min.

[0038] Step 2: Prepare a polishing mixture with a pH of 8.6, which includes 60 ml of OPS silicon oxide suspension (particle size 60 nm) and 5 ml of cresol soap solution (concentration 3%).

[0039] Step three: Use a grinding and polishing machine to perform mechanical polishing on the titanium alloy sample ground in step one; wherein, the polishing machine pressure is set to 15N, the polishing speed is set to 200rpm, the polishing time is set to 8min, and the polishing liquid flow rate is set to 20ml / min.

[0040] Step 4: Use 10% oxalic acid as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.

[0041] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 60s, wipe, then immediately rinse with clean running water and dry.

[0042] It was found that the sample in Example 1 was polished to a high degree of cleanliness, without scratches and dirt defects, and the microstructure resolution effect after corrosion was good, and the grain boundaries were clearly visible.

[0043] Embodiment 2:

[0044] The metallographic sample preparation method of the titanium alloy of this embodiment specifically comprises the following steps:

[0045] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 30N, the grinding speed to 180rpm, and the grinding time to 6min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 5N, the grinding speed to 150rpm, and the grinding time to 4min.

[0046] Step 2: Prepare a polishing mixture with a pH of 8.8, which includes 50 ml of OPS silicon oxide suspension (particle size 100 nm) and 4 ml of cresol soap solution (concentration 2%).

[0047] Step 3: Use a grinding and polishing machine to mechanically polish the titanium alloy sample ground in step 1; wherein, the polishing machine pressure is set to 15N, the polishing speed is set to 160rpm, the polishing time is set to 7min, and the polishing liquid flow rate is set to 25ml / min.

[0048] Step 4: Use 10% oxalic acid as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.1.

[0049] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 65s, wipe, then immediately rinse with clean running water and dry.

[0050] It was found that the sample in Example 2 was polished to a high degree of cleanliness, without scratches and dirt defects, and the microstructure resolution effect after corrosion was good, and the grain boundaries were clearly visible.

[0051] Embodiment 3:

[0052] The metallographic sample preparation method of the titanium alloy of this embodiment specifically comprises the following steps:

[0053] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 20N, the grinding speed to 240rpm, and the grinding time to 5.5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 4min.

[0054] Step 2: Prepare a polishing mixture with a pH of 8.7, which includes 55 ml of OPS silicon oxide suspension (particle size 80 nm) and 6 ml of cresol soap solution (concentration 4%).

[0055] Step 3: Use a grinding and polishing machine to perform mechanical polishing on the titanium alloy sample ground in step 1; wherein, the polishing machine pressure is set to 15N, the polishing speed is set to 180rpm, the polishing time is set to 9min, and the polishing liquid flow rate is set to 20ml / min.

[0056] Step 4: Use 10% oxalic acid as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.

[0057] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 80s, wipe, then immediately rinse with clean running water and dry.

[0058] It was found that the sample in Example 3 was polished to a high degree of cleanliness, without scratches and dirt defects, and the microstructure resolution effect after corrosion was good, and the grain boundaries were clearly visible.

[0059] Embodiment 4:

[0060] The metallographic sample preparation method of the titanium alloy of this embodiment specifically comprises the following steps:

[0061] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 20N, the grinding speed to 220rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 160rpm, and the grinding time to 4min.

[0062] Step 2: Prepare a polishing mixture with a pH of 9. The mixture includes 58 ml of OPS silicon oxide suspension (particle size 0.02 μm) and 5 ml of cresol soap solution (concentration 4%).

[0063] Step three: Use a grinding and polishing machine to mechanically polish the titanium alloy sample ground in step one; wherein, the polishing machine pressure is set to 15N, the polishing speed is set to 200rpm, the polishing time is set to 10min, and the polishing liquid flow rate is set to 25ml / min.

[0064] Step 4: Use 10% oxalic acid as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.2.

[0065] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 60s, wipe, then immediately rinse with clean running water and dry.

[0066] It was found that the sample in Example 4 was polished to a high degree of cleanliness, without scratches and dirt defects, and the microstructure resolution effect after corrosion was good, and the grain boundaries were clearly visible.

[0067] Comparative Example 1:

[0068] The metallographic sample preparation method of the titanium alloy in this comparative example specifically comprises the following steps:

[0069] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 40N, the grinding speed to 300rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 40N, the grinding speed to 300rpm, and the grinding time to 4min.

[0070] Step 2: Prepare a polishing mixture with a pH of 9. The mixture includes 50 ml of OPS silicon oxide suspension (particle size 80 nm) and 8 ml of cresol soap solution (concentration 3%).

[0071] Step three: Use a grinding and polishing machine to mechanically polish the titanium alloy sample ground in step one; wherein, the polishing machine pressure is set to 40N, the polishing speed is set to 300rpm, the polishing time is set to 7min, and the polishing liquid flow rate is set to 25ml / min.

[0072] Step 4: Use 10% oxalic acid as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.

[0073] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 70s, wipe, then immediately rinse with clean running water and dry.

[0074] It was found that the sample in Comparative Example 1 was polished to a high degree of cleanliness, without obvious scratches and dirt defects. However, the pressure was set too high during grinding and polishing, and there were uneven ripples on the surface of the sample, which still existed after corrosion, affecting subsequent tissue observation.

[0075] Comparative Example 2:

[0076] The metallographic sample preparation method of the titanium alloy in this comparative example specifically comprises the following steps:

[0077] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 5N, the grinding speed to 200rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 5min.

[0078] Step 2: Prepare a polishing mixture with a pH of 9.2, which includes 60 ml of OPS silicon oxide suspension (particle size 60 nm) and 4 ml of cresol soap solution (concentration 3%).

[0079] Step three: Use a grinding and polishing machine to mechanically polish the titanium alloy sample ground in step one; wherein, the polishing machine pressure is set to 5N, the polishing speed is set to 150rpm, the polishing time is set to 3min, and the polishing liquid flow rate is set to 20ml / min.

[0080] Step 4: Use 10% oxalic acid as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.3.

[0081] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 100s, wipe, then immediately rinse with clean running water and dry.

[0082] It was found that the sample in Comparative Example 2 had a high degree of polishing cleanliness. However, due to the low polishing pressure setting and short polishing time, there were scratches that were not polished clean, which affected the subsequent tissue observation.

[0083] Comparative Example 3:

[0084] The metallographic sample preparation method of the titanium alloy in this comparative example specifically comprises the following steps:

[0085] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 15N, the grinding speed to 250rpm, and the grinding time to 6min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 100rpm, and the grinding time to 5min.

[0086] Step 2: Prepare a polishing mixture with a pH of 8.6. The mixture includes 56 ml of OPS silicon oxide suspension (particle size 0.02 μm) and 2 ml of cresol soap solution (concentration 3%).

[0087] Step three: Use a grinding and polishing machine to perform mechanical polishing on the titanium alloy sample ground in step one; wherein, the polishing machine pressure is set to 15N, the polishing speed is set to 200rpm, the polishing time is set to 8min, and the polishing liquid flow rate is set to 20ml / min.

[0088] Step 4: Use oxalic acid with a concentration of 20% as a pH regulator, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 6.6.

[0089] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 60s, wipe, then immediately rinse with clean running water and dry.

[0090] It was found that in Comparative Example 3, due to the small amount of cresol soap solution and the large amount of oxalic acid solution during neutralization and cleaning, the polishing cleanliness of the sample was poor, and a small amount of black spots and dirt existed on the surface that could not be polished away, affecting subsequent tissue observation.

[0091] Comparative Example 4:

[0092] The metallographic sample preparation method of the titanium alloy of this embodiment specifically comprises the following steps:

[0093] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 20N, the grinding speed to 180rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 4min.

[0094] Step 2: Prepare a polishing mixture with a pH of 9.3, which includes 80 ml of OPS silicon oxide suspension (particle size 60 nm) and 5 ml of cresol soap solution (concentration 2%).

[0095] Step three: Use a grinding and polishing machine to mechanically polish the titanium alloy sample ground in step one; wherein, the polishing machine pressure is set to 15N, the polishing speed is set to 200rpm, the polishing time is set to 20min, and the polishing liquid flow rate is set to 40ml / min.

[0096] Step 4: Use oxalic acid with a concentration of 5% as a pH adjuster, and put the polished sample in step 3 into the oxalic acid solution to adjust the pH to 7.8.

[0097] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation. The corrosion solution used is 10mL HF + 25mL HNO 3 +65mL H 2 O mixture, corrosion time 70s, wipe, then immediately rinse with clean running water and dry.

[0098] It was found that in Comparative Example 4, due to the excessive flow rate of the polishing liquid and the long polishing time, the polishing cleanliness of the sample was poor, and a small amount of black spots and dirt existed on the surface that could not be polished away, affecting the subsequent tissue observation.

[0099] Comparative Example 5:

[0100] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 20N, the grinding speed to 200rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 4min.

[0101] Step 2: Prepare a polishing mixture. The mixture includes a polishing agent and an oxidant, the polishing agent is 60 ml of a silicon dioxide suspension, and the oxidant is 4 ml of a hydrogen peroxide solution.

[0102] Step 3: Use a grinding and polishing machine to perform mechanical polishing on the titanium alloy sample ground in step 1. In step 3, the polishing machine pressure is set to 15N, the polishing speed is set to 160rpm, the polishing time is set to 5min, and the polishing liquid flow rate is set to 20ml / min.

[0103] Step 4: Clean the sample with anhydrous ethanol and dry it to complete mechanical polishing of the sample.

[0104] Step 5: Perform OM observation on the polished sample after drying.

[0105] It was found that the polishing cleanliness of the sample in Comparative Example 5 was relatively good, with a small amount of scratches and black spot defects.

[0106] Comparative Example 6:

[0107] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 15N, the grinding speed to 200rpm, and the grinding time to 6min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 4min.

[0108] Step 2: Prepare polishing liquid. The mixed liquid includes polishing agent and oxidant, the polishing agent is 60 ml of diamond polishing agent, and the oxidant is 5 ml of cresol soap solution. The concentration of cresol soap solution in step 2 is 2%.

[0109] Step 3: Use a grinding and polishing machine to perform mechanical polishing on the titanium alloy sample ground in step 1. In step 3, the polishing machine pressure is set to 10N, the polishing speed is set to 180rpm, the polishing time is set to 8min, and the polishing liquid flow rate is set to 24ml / min.

[0110] Step 4: Use 10% oxalic acid as a pH adjuster, and put the polished sample in step 3 into the oxalic acid solution for pH neutralization, and adjust the pH to 7.1.

[0111] Step 5: Use an ultrasonic cleaner to clean the sample, then dry it to complete mechanical polishing. Perform OM observation on the polished sample after drying.

[0112] It was found that there were a large number of scratches on the sample in Comparative Example 6 after polishing and that they could not be polished away, which would seriously affect the subsequent tissue analysis.

[0113] Comparative Example 7:

[0114] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 20N, the grinding speed to 200rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 4min.

[0115] Step 2: Prepare the polishing liquid as 60 ml of silica suspension.

[0116] Step 3: Use a grinding and polishing machine to mechanically polish the titanium alloy sample ground in step 1. In step 3, the polishing machine pressure is set to 20N, the polishing speed is set to 200rpm, the polishing time is set to 7min, and the polishing liquid flow rate is set to 22ml / min.

[0117] Step 4: Clean the sample with anhydrous ethanol and dry it to complete mechanical polishing of the sample.

[0118] Step 5: Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation.

[0119] It was found that the polishing cleanliness of the sample in Comparative Example 7 was very poor, with many black spot defects and dirt on the surface. After corrosion, the black spot defects and dirt were inherited, and the tissue resolution effect was poor.

[0120] Comparative Example 8:

[0121] Step 1: Use a grinding and polishing machine to mechanically grind the titanium alloy sample under different sandpapers. When the sandpaper roughness is less than 800 mesh, set the grinding machine pressure to 15N, the grinding speed to 200rpm, and the grinding time to 5min; when the sandpaper roughness is ≥800 mesh, set the grinding machine pressure to 15N, the grinding speed to 150rpm, and the grinding time to 4min.

[0122] Step 2: Prepare the polishing liquid as 60 ml of OPS silicon oxide suspension.

[0123] Step 3: Use a grinding and polishing machine to perform mechanical polishing on the titanium alloy sample ground in step 1. In step 3, the polishing machine pressure is set to 40N, the polishing speed is set to 300rpm, the polishing time is set to 15min, and the polishing liquid flow rate is set to 30ml / min.

[0124] Step 4: Clean the sample with anhydrous ethanol and dry it to complete mechanical polishing of the sample.

[0125] Step 5: Perform OM observation on the polished sample after drying, then perform corrosion to prepare the metallographic sample and complete the organization observation.

[0126] It was found that the polishing cleanliness of the sample in Comparative Example 8 was very poor. Not only were there many black spot defects and dirt on the surface, but there were also a large number of uneven ripples. After corrosion, the black spot defects and dirt were inherited, and the tissue resolution effect was poor.

[0127] Table 1 Polishing methods and display effects in embodiments and comparative examples

[0128]

[0129]

[0130] According to the results in Table 1 and Table 2, the samples in Examples 1-4 have a high degree of polishing cleanliness, achieving a mirror-like smooth effect, without scratches and dirt defects, and the metallographic structure resolution effect after corrosion is good; after polishing, the samples in Comparative Examples 1-5 have the disadvantages of uneven ripples, a small amount of scratches and black spots and dirt on the surface; the polished surfaces in Comparative Examples 6 to 8 have the disadvantages of a large number of scratches, a large number of black spot defects and dirt, and a large number of uneven ripples.

[0131] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for metallographic sample preparation of titanium alloy, characterized in that: The following steps are involved: Provide titanium alloy specimens; Mechanically grinding the titanium alloy sample to obtain a mechanically ground titanium alloy sample; The titanium alloy sample after mechanical grinding is mechanically polished by using a chemical polishing agent, and the pH is adjusted to 7 to 7.3 by using a pH adjusting agent, and then the sample is cleaned and dried in sequence to obtain a polished titanium alloy sample; The polished titanium alloy sample is corroded by using a metallographic corrosive agent to obtain a titanium alloy metallographic sample.

2. The method for metallographic sample preparation of titanium alloy according to claim 1, characterized in that: The chemical polishing agent comprises a polishing agent and an oxidizing agent; The polishing agent is OPS silicon oxide suspension; The oxidant comprises a cresol soap solution with a concentration of 1% to 5%; The volume ratio of the OPS silicon oxide suspension to the cresol soap solution is (50-60):(4-8).

3. The method for metallographic sample preparation of titanium alloy according to claim 2, characterized in that: The particle size of silicon oxide in the OPS silicon oxide suspension is 50 nm to 0.05 μm.

4. The method for metallographic sample preparation of titanium alloy according to claim 1, characterized in that: The pH of the chemical polishing agent is 8 to 9.

5.

5. The method for metallographic sample preparation of titanium alloy according to claim 1, characterized in that: The mechanical grinding uses sandpaper with a roughness of 120 mesh to 2000 mesh.

6. The method for metallographic sample preparation of titanium alloy according to claim 5, characterized in that: When the roughness of the sandpaper is less than 800 mesh, the grinding pressure of the mechanical grinding is 20N to 30N, the grinding speed of the mechanical grinding is 150rpm to 250rpm, and the grinding time of the mechanical grinding is 5min to 6.5min; When the roughness of the sandpaper is ≥800 mesh, the grinding pressure of the mechanical grinding is 5N-15N, the grinding speed of the mechanical grinding is 100rpm-150rpm, and the grinding time of the mechanical grinding is 3.5min-5min.

7. The method for metallographic sample preparation of titanium alloy according to claim 1, characterized in that: The polishing machine pressure of the mechanical polishing is 15N-20N, the polishing speed of the mechanical polishing is 150rpm-200rpm, the polishing time of the mechanical polishing is 6min-10min, and the polishing liquid flow rate of the mechanical polishing is 20ml / min-25ml / min.

8. The method for metallographic sample preparation of titanium alloy according to claim 1, characterized in that: The pH regulator is a 10% oxalic acid solution.

9. The method for metallographic sample preparation of titanium alloy according to claim 1, characterized in that: The metallographic etching agent is hydrofluoric acid, nitric acid and water in a volume ratio of 10:25:35.

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