A method for displaying the grain structure of TA22 titanium alloy

Abstract

The application discloses a kind of TA22 titanium alloy grain structure's corrosion display method, the method comprises: one, the sample of TA22 titanium alloy is mechanically processed to microstructure observation plane and grinds and washes;Two, mechanical polishing until surface is smooth and bright, no scratch and drag;Three, anodic oxidation coating treatment;Four, immerse in corrosion solution and carry out immersion corrosion;Five, under metallographic microscope, adopt the way of field observation to carry out metallographic microstructure observation.The application is by to TA22 titanium alloy first anodic oxidation coating, then corrosion film removal, discards the method that different light and shade contrast in metallographic structure is observed using polarized field after coating, judges grain size, directly under metallographic microscope using field observation can clearly, accurately, intuitively observe the grain boundary structure in the metallographic structure of TA22 titanium alloy, need not switch polarized field, greatly reduce the equipment requirement to metallographic microscope, method is easy to operate, suitable for promotion and application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal material metallographic microstructure observation, and particularly relates to a corrosion display method of TA22 titanium alloy grain structure. BACKGROUND

[0002] TA22, also known as Ti31 alloy, is a near-alpha titanium alloy independently developed by China. The nominal composition of the alloy is Ti-3Al-1Mo-1Ni-1Zr. The alloy has high plasticity and toughness, medium-temperature thermal strength and high-temperature durability, and also has good fatigue resistance and wear resistance, so that it can maintain stable performance during long-term use. In addition, the TA22 titanium alloy can exhibit good corrosion resistance in various harsh environments. It can work stably in extreme environments such as high temperature, high pressure, strong acid and strong alkali without corrosion and oxidation. This makes TA22 titanium alloy one of the important materials in the fields of chemical industry and ocean engineering.

[0003] Grain size refers to the size of the grains in the crystal, which is an important physical property parameter in titanium alloy. The grain size directly affects the mechanical properties and processing performance of titanium alloy. The smaller the grain size, the higher the strength and plasticity of the material, and the better the thermal conductivity and toughness. Large grain size will increase the hardness and brittleness of the alloy, and the finished product is prone to cracking and deformation. Therefore, controlling the grain size of titanium alloy can effectively improve the mechanical properties and processing performance of the alloy. Grain size rating is an effective means to control the grain size of titanium alloy, which can ensure the mechanical properties and processing performance of the alloy and optimize and control the manufacturing process of titanium alloy.

[0004] At present, the TA22 titanium alloy cannot be observed after being corroded by a conventional corrosion agent. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a corrosion display method of TA22 titanium alloy grain structure to solve the above-mentioned problems of the prior art. The method discards the method of observing the different light and dark contrasts in the metallographic structure by polarized field observation after plating film to judge the grain size, and directly observes the grain boundary structure in the metallographic microstructure under the metallographic microscope by field observation, which is clear, accurate and intuitive, without switching the polarized field, greatly reducing the equipment requirements for the metallographic microscope, and solving the problem that the grain boundary structure of TA22 titanium alloy cannot be observed by the conventional corrosion agent.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a corrosion display method of TA22 titanium alloy grain structure, characterized in that the method comprises the following steps:

[0007] Step one, the sample of TA22 titanium alloy is mechanically processed into a microstructure observation plane, and then the microstructure observation plane is ground on a metallographic pre-grinding machine, and the sand particles on the microstructure observation plane are washed off;

[0008] Step two, the microstructure observation plane with the sand particles washed off in step one is placed on a polishing machine for mechanical polishing until the surface of the microstructure observation plane is smooth and bright, free of scratches and dragging;

[0009] Step three, the microstructure observation plane after mechanical polishing in step two is subjected to anodic oxidation film treatment for 2s-5s;

[0010] Step four, the microstructure observation plane after anodic oxidation film treatment in step three is immersed in a corrosion solution for immersion corrosion;

[0011] Step five, the microstructure observation plane after immersion corrosion in step four is placed under a metallographic microscope, and the metallographic microstructure is observed by field observation.

[0012] In the research process of the present application, it is found that the conventional corrosion solution in the national standard, such as hydrofluoric acid nitric acid aqueous solution, is used to corrode the TA22 titanium alloy (5% HF+12% HNO3+83% H2O by volume ratio, corrosion, 5s), and the metallographic structure diagram is as shown in Figure 1 Although the metallographic microstructure can be seen, the grain boundary structure cannot be shown, and the grain size cannot be clearly identified, which is easy to draw a wrong conclusion. If the conventional corrosion is followed by anodic oxidation film treatment, it is necessary to use the polarized field of the metallographic microscope for observation, and the equipment requirement is relatively high. If the metallographic microscope is not equipped with a polarizing lens, the clear grain structure cannot be observed. Based on this, the present application adopts a sequence different from the conventional corrosion and film plating of titanium alloy, that is, the TA22 titanium alloy after grinding and mechanical polishing is first subjected to anodic oxidation film treatment, and then the TA22 titanium alloy after anodic oxidation is subjected to "film removal" treatment by using a corrosion solution for immersion corrosion. The method of observing the metallographic structure by using the different light and dark contrast of the film after plating is abandoned, so that the microstructure observation plane can be directly placed under the metallographic microscope for observation by field observation, and the grain boundary structure in the metallographic structure of the TA22 titanium alloy observed is very clear, accurate and intuitive, without the need to switch the polarized field, which greatly reduces the equipment requirement of the metallographic microscope.

[0013] The above-mentioned corrosion display method of the grain structure of TA22 titanium alloy, wherein the specific process of grinding in step one is: 120 # , 800 # , 1200# and 2000 #The metallographic water sand paper is gradually ground, and the grinding direction is rotated by 90 degrees at each time when the metallographic water sand paper is replaced to ensure that the last grinding trace is completely eliminated.

[0014] The corrosion display method of the TA22 titanium alloy grain structure has the features that the polishing agent of the mechanical polishing in the step two is a 0.5-micron SiO2 suspension, and the polishing cloth is a damping polishing cloth.

[0015] The corrosion display method of the TA22 titanium alloy grain structure has the features that the solution of the anodic oxidation film treatment in the step three is a 5%-mass H2SO4 aqueous solution, the equipment is an adjustable voltage-stabilizing constant-current source, the voltage of the anodic oxidation film treatment is 18-25 V, the current is 0.8-1.0 A, and the time is 1-3 s.

[0016] The corrosion display method of the TA22 titanium alloy grain structure has the features that the corrosion solution in the step four is composed of a 5%-volume HF aqueous solution, and the etching time is 3-8 s.

[0017] The corrosion display method of the TA22 titanium alloy grain structure has the features that the H2SO4 in the H2SO4 aqueous solution is an analytical reagent.

[0018] The corrosion display method of the TA22 titanium alloy grain structure has the features that the HF in the HF aqueous solution is an analytical reagent.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1. The present application adopts a sequence different from the conventional sequence of first corrosion and then film plating, that is, first anodic oxidation film plating and then etching film removal, discards the method of observing the different light and dark contrasts in the metallographic structure after film plating to judge the grain size, and directly observes the grain boundary structure in the metallographic structure of the TA22 titanium alloy under the metallographic microscope.

[0021] 2. Compared with conventional corrosion methods, which can only observe the metallographic structure but not the grain boundary structure, the method of the present invention can clearly and specifically observe the grain boundary structure of TA22 titanium alloy under bright field of view of a metallographic microscope. This is beneficial to ensure the mechanical and processing properties of TA22 titanium alloy through grain size rating.

[0022] 3. The method of the present invention is easy to operate and non-toxic. It can clearly observe the grain structure of TA22 titanium alloy and does not require any special equipment. It also does not require higher requirements such as polarizing microscope observation, which greatly reduces the equipment requirements for metallurgical microscopes and is suitable for widespread application.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 The image shows the metallographic structure of TA22 titanium alloy after etching with a conventional etching solution within the national standard.

[0025] Figure 2 This is a microstructure (400×) of the TA22 titanium alloy grain structure in Example 1 of the present invention.

[0026] Figure 3 This is a microstructure (400×) of the TA22 titanium alloy grain structure in Example 2 of the present invention.

[0027] Figure 4 This is a microstructure (400×) of the TA22 titanium alloy grain structure in Example 3 of the present invention.

[0028] Figure 5 This is a microstructure (400×) of the TA22 titanium alloy grain structure in Example 4 of the present invention.

[0029] Figure 6 This is a microstructure (400×) of the TA22 titanium alloy grain structure in Example 5 of the present invention.

[0030] Figure 7 This is a microstructure (400×) of the TA22 titanium alloy grain structure in Example 6 of the present invention. Detailed Implementation

[0031] Example 1

[0032] This embodiment includes the following steps:

[0033] Step 1: Machining the TA22 titanium alloy sample to create a microstructure observation plane, then grinding the microstructure observation plane on a metallographic pre-grinding machine and washing away the abrasive particles on the microstructure observation plane; the specific grinding process is as follows: sequentially using a 120 grit particle size...# , 800 # , 1200# and 2000 # The metallographic water sand paper is gradually ground, and the grinding direction is rotated by 90° at each time of replacing the metallographic water sand paper for grinding, so as to ensure that the last grinding trace is completely eliminated.

[0034] Step two, the microstructure observation plane rinsed of sand particles in step one is placed on a polishing machine for mechanical polishing until the surface of the microstructure observation plane is smooth and bright, free of scratches and dragging; the polishing agent of the mechanical polishing is a SiO2 suspension with a particle size of 0.5 μm, and the polishing cloth is a damping polishing cloth;

[0035] Step three, the microstructure observation plane after the mechanical polishing in step two is subjected to anodic oxidation film treatment; the solution of the anodic oxidation film treatment is a 5% H2SO4 aqueous solution, and the H2SO4 in the H2SO4 aqueous solution is an analytical reagent, the equipment is an adjustable voltage-stabilized constant current source, and the voltage of the anodic oxidation film treatment is 18 V, the current is 0.8 A, and the time is 1 s;

[0036] Step four, the microstructure observation plane after the anodic oxidation film treatment in step three is immersed in an etching solution for immersion etching; the etching solution is composed of 5% HF aqueous solution by volume percentage, and the HF in the HF aqueous solution is an analytical reagent, and the immersion etching time is 3 s;

[0037] Step five, the microstructure observation plane after the immersion etching in step four is placed under a metallographic microscope, and the metallographic microstructure is observed by using a bright field observation method.

[0038] Figure 2 is a microstructure diagram (400x) of the grain structure of the TA22 titanium alloy in this embodiment, from Figure 2 It can be seen that the background color is light brown after the anodic oxidation film is removed, the grain boundary of the TA22 titanium alloy grain is white, and the grain boundary details are clearly visible.

[0039] Example 2

[0040] This embodiment includes the following steps:

[0041] Step one, a microstructure observation plane of a TA22 titanium alloy sample is mechanically processed, and then the microstructure observation plane is ground on a metallographic pre-polishing machine and rinsed of sand particles; the specific process of the grinding is as follows: 120 # , 800 # , 1200# and 2000 #The metallographic water sandpaper is gradually ground, and the grinding direction is rotated by 90 degrees when the metallographic water sandpaper is replaced each time to ensure that the last grinding trace is completely eliminated.

[0042] Step two, the microstructure observation plane rinsed of sand particles in step one is placed on a polishing machine for mechanical polishing until the microstructure observation plane surface is smooth and bright, free of scratches and dragging; the polishing agent for the mechanical polishing is a 0.5 μm particle size SiO2 suspension, and the polishing cloth is a damping polishing cloth;

[0043] Step three, the microstructure observation plane after the mechanical polishing in step two is subjected to anodic oxidation film treatment; the solution for the anodic oxidation film treatment is a 5% mass concentration H2SO4 aqueous solution, and the H2SO4 in the H2SO4 aqueous solution is an analytical reagent, the equipment is an adjustable voltage-stabilized constant current source, and the voltage for the anodic oxidation film treatment is 18 V, the current is 0.8 A, and the time is 2 s;

[0044] Step four, the microstructure observation plane after the anodic oxidation film treatment in step three is immersed in an etching solution for immersion etching; the etching solution is composed of 5% by volume HF aqueous solution, and the HF in the HF aqueous solution is an analytical reagent, and the immersion etching time is 6 s;

[0045] Step five, the microstructure observation plane after the immersion etching in step four is placed under a metallographic microscope, and the metallographic microstructure is observed in a bright field observation mode.

[0046] Figure 3 is a microstructure diagram (400x) of the grain structure of the TA22 titanium alloy in this embodiment, from Figure 3 It can be seen that the light yellow background color gradually disappears, the grain boundaries of the TA22 titanium alloy grain are black, and the grain boundary details are clearly visible.

[0047] Example 3

[0048] This embodiment includes the following steps:

[0049] Step one, a microstructure observation plane of a TA22 titanium alloy sample is mechanically processed, and then the microstructure observation plane is ground on a metallographic pre-polishing machine and rinsed of sand particles on the microstructure observation plane; the specific process of the grinding is as follows: 120 # , 800 # , 1200# and 2000 # metallographic water sandpaper is gradually ground, and the grinding direction is rotated by 90 degrees when the metallographic water sandpaper is replaced each time to ensure that the last grinding trace is completely eliminated.

[0050] Step two, the microstructure observation plane rinsed of sand in step one is placed on a polishing machine for mechanical polishing until the microstructure observation plane surface is smooth and bright, free of scratches and dragging; the polishing agent for the mechanical polishing is a 0.5 pm SiO2 suspension, and the polishing cloth is a damping polishing cloth;

[0051] Step three, the microstructure observation plane after the mechanical polishing in step two is subjected to anodic oxidation film treatment; the solution for the anodic oxidation film treatment is a 5% H2SO4 aqueous solution, and the H2SO4 in the H2SO4 aqueous solution is an analytical reagent, the equipment is an adjustable voltage-stabilized constant current source, and the voltage for the anodic oxidation film treatment is 20 V, the current is 1.0 A, and the time is 3 s;

[0052] Step four, the microstructure observation plane after the anodic oxidation film treatment in step three is immersed in a corrosion solution for immersion etching; the corrosion solution is composed of a 5% HF aqueous solution, and the HF in the HF aqueous solution is an analytical reagent, and the immersion etching time is 3 s;

[0053] Step five, the microstructure observation plane after the immersion etching in step four is placed under a metallographic microscope, and the metallographic microstructure is observed in a bright field observation mode.

[0054] Figure 4 The microstructure of the TA22 titanium alloy grain structure in this embodiment is shown in Figure 4 (400x), from which Figure 4 It can be seen that the background color is a grayish white color after further removal of the anodic oxidation film, the TA22 titanium alloy grain boundary is relatively shallow, and the grain boundary details are clearly visible.

[0055] Example 4

[0056] This embodiment includes the following steps:

[0057] Step one, a microstructure observation plane of a TA22 titanium alloy sample is mechanically processed, and then the microstructure observation plane is ground on a metallographic pre-grinding machine and rinsed to remove sand on the microstructure observation plane; the specific process of the grinding is as follows: the metallographic water sandpaper with particle sizes of 120 # , 800 # , 1200# and 2000 # are sequentially used for step-by-step grinding, and the grinding direction is rotated by 90° at each time of replacing the metallographic water sandpaper for grinding to ensure complete elimination of the grinding marks of the previous time;

[0058] Step two, the microstructure observation plane rinsed of sand in step one is placed on a polishing machine for mechanical polishing until the microstructure observation plane surface is smooth and bright, free of scratches and dragging; the polishing agent for the mechanical polishing is a 0.5 pm SiO2 suspension, and the polishing cloth is a damping polishing cloth;

[0059] Step three, the microstructure observation plane after mechanical polishing in step two is treated by anodic oxidation film coating; the solution for the anodic oxidation film coating treatment is 5% H2SO4 aqueous solution, and the H2SO4 in the H2SO4 aqueous solution is an analytical reagent, the equipment is an adjustable voltage stabilizing constant current source, and the voltage for the anodic oxidation film coating treatment is 20V, the current is 1.0A, and the time is 3s;

[0060] Step four, the microstructure observation plane after the anodic oxidation film coating treatment in step three is immersed in a corrosion solution for etching; the corrosion solution is composed of 5% HF aqueous solution, and the HF in the HF aqueous solution is an analytical reagent, and the etching time is 5s;

[0061] Step five, the microstructure observation plane after etching in step four is placed under a metallographic microscope, and the metallographic microstructure is observed by using a field observation method.

[0062] Figure 2 The microstructure diagram (400x) of the TA22 titanium alloy grain structure in this embodiment is shown in Figure 4, from which Figure 2 It can be seen that the bottom color is grayish white after further removing the anodic oxidation film, the TA22 titanium alloy grain boundary is deep, black, and the grain boundary details are clearly visible.

[0063] Example 5

[0064] This embodiment includes the following steps:

[0065] Step one, a microstructure observation plane of a TA22 titanium alloy sample is mechanically processed, and then the microstructure observation plane is ground on a metallographic pre-grinding machine, and the sand particles on the microstructure observation plane are washed off; the specific process of the grinding is as follows: the metallographic water sandpaper with particle sizes of 120 # , 800 # , 1200# and 2000 # are used for step-by-step grinding, and the grinding direction is rotated by 90° at each time of replacing the metallographic water sandpaper for grinding, so as to ensure that the traces of the last grinding are completely eliminated;

[0066] Step two, the microstructure observation plane with the sand particles washed off in step one is placed on a polishing machine for mechanical polishing until the surface of the microstructure observation plane is smooth and bright, without scratches and dragging; the polishing agent for the mechanical polishing is SiO2 suspension with a particle size of 0.5μm, and the polishing cloth is a damping polishing cloth;

[0067] Step three, the microstructure observation plane after mechanical polishing in step two is treated by anodic oxidation film coating; the solution for the anodic oxidation film coating treatment is 5% H2SO4 aqueous solution, and the H2SO4 in the H2SO4 aqueous solution is an analytical reagent, the equipment is an adjustable voltage stabilizing constant current source, and the voltage for the anodic oxidation film coating treatment is 20 V, the current is 1.0 A, and the time is 3 s;

[0068] Step four, the microstructure observation plane after the anodic oxidation film coating treatment in step three is immersed in a corrosion solution for immersion etching; the corrosion solution is composed of 5% HF aqueous solution, and the HF in the HF aqueous solution is an analytical reagent, and the immersion etching time is 7 s;

[0069] Step five, the microstructure observation plane after immersion etching in step four is placed under a metallographic microscope, and the metallographic microstructure is observed by bright field observation.

[0070] Figure 6 The microstructure diagram (400x) of the TA22 titanium alloy grain structure in this embodiment is shown in Figure 1. Figure 6 It can be seen that the bottom color is grayish white after further removing the anodic oxidation film, the TA22 titanium alloy grain boundary is relatively shallow and thick, and the grain boundary details are clearly visible.

[0071] Example 6

[0072] This embodiment includes the following steps:

[0073] Step one, a microstructure observation plane of a TA22 titanium alloy sample is mechanically processed, and then the microstructure observation plane is ground on a metallographic pre-grinding machine, and the sand particles on the microstructure observation plane are washed off; the specific process of the grinding is as follows: the metallographic water sandpaper with particle sizes of 120 # , 800 # , 1200# and 2000 # are used for step-by-step grinding, and the grinding direction is rotated by 90° at each time of replacing the metallographic water sandpaper for grinding, so as to ensure that the traces of the last grinding are completely eliminated;

[0074] Step two, the microstructure observation plane with the sand particles washed off in step one is placed on a polishing machine for mechanical polishing until the surface of the microstructure observation plane is smooth and bright, without scratches and dragging; the polishing agent for the mechanical polishing is SiO2 suspension with a particle size of 0.5 μm, and the polishing cloth is a damping polishing cloth;

[0075] Step three, the microstructure observation plane after mechanical polishing in step two is treated by anodic oxidation film coating; the solution for the anodic oxidation film coating treatment is 5% H2SO4 aqueous solution, and the H2SO4 in the H2SO4 aqueous solution is an analytically pure reagent, the equipment is an adjustable voltage-stabilized constant current source, and the voltage for the anodic oxidation film coating treatment is 25 V, the current is 1.0 A, and the time is 2 s;

[0076] Step four, the microstructure observation plane after the anodic oxidation film coating treatment in step three is immersed in a corrosion solution for etching; the corrosion solution is composed of 5% HF aqueous solution, and the HF in the HF aqueous solution is an analytically pure reagent, and the etching time is 8 s;

[0077] Step five, the microstructure observation plane after etching in step four is placed under a metallographic microscope, and the metallographic microstructure is observed by using a field observation method.

[0078] Figure 7 The microstructure diagram (400x) of the TA22 titanium alloy grain structure in this embodiment is shown in Fig. 4. Figure 7 It can be seen that the bottom color is dark brown and white, the TA22 titanium alloy grain boundary is relatively shallow and thick, is black, and the grain boundary details are clearly visible.

[0079] The above description is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent change made according to the technical essence of the present application to the above embodiment are still within the protection scope of the technical solution of the present application.

Claims

1. A method for displaying the corrosion microstructure of TA22 titanium alloy, characterized in that, The method includes the following steps: Step 1: Machining the TA22 titanium alloy sample to create a microstructure observation plane, then grinding the microstructure observation plane on a metallographic pre-grinding machine and washing away the sand particles on the microstructure observation plane. Step 2: Place the microstructure observation plane, from which the sand particles were washed away in Step 1, on a polishing machine for mechanical polishing until the surface of the microstructure observation plane is smooth, shiny, and free of scratches and drag. Step 3: Perform anodizing coating on the microstructure observation plane after mechanical polishing in Step 2 for 1s~3s; Step 4: Immerse the microstructure observation plane, which has undergone anodizing coating in Step 3, into the etching solution for etching. Step 5: Place the microstructure observation plane after etching in Step 4 under a metallographic microscope and observe the metallographic microstructure using bright field observation.

2. The corrosion visualization method for TA22 titanium alloy grain structure according to claim 1, characterized in that, The specific grinding process described in step one is as follows: Grinding is carried out sequentially using particles with a particle size of 120... # 800 # 1200 # and 2000 # Use wet metallographic sandpaper to grind step by step. Each time you change wet metallographic sandpaper, rotate the grinding direction by 90° to ensure that the grinding marks from the previous grinding are completely removed.

3. The corrosion visualization method for TA22 titanium alloy grain structure according to claim 1, characterized in that, The polishing agent used in step two is a SiO2 suspension with a particle size of 0.5 μm, and the polishing cloth is a damping polishing cloth.

4. The corrosion visualization method for TA22 titanium alloy grain structure according to claim 1, characterized in that, The solution for the anodic oxidation coating treatment in step three is a 5% (w / w) H2SO4 aqueous solution. The equipment is an adjustable voltage and constant current source, and the voltage for the anodic oxidation coating treatment is 18V~25V, the current is 0.8A~1.0A, and the time is 1s~3s.

5. The corrosion visualization method for TA22 titanium alloy grain structure according to claim 1, characterized in that, The corrosion solution in step four consists of a 5% (by volume) HF aqueous solution, and the immersion time is 3 to 8 seconds.

6. The corrosion visualization method for TA22 titanium alloy grain structure according to claim 4, characterized in that, The H2SO4 in the aqueous solution is an analytical grade reagent.

7. The corrosion visualization method for TA22 titanium alloy grain structure according to claim 5, characterized in that, The HF in the HF aqueous solution is an analytical grade reagent.

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