Steel fracture cleaning fluid as well as preparation method and application thereof

Abstract

The invention relates to a steel fracture cleaning solution as well as a preparation method and application thereof, and relates to the technical field of fracture failure analysis. The steel fracture cleaning solution comprises the following components: citric acid, hydrochloric acid, glycerol, a corrosion inhibitor and water. According to the fracture cleaning fluid, the raw materials are extremely easy to obtain, the cost is low, and the fracture cleaning fluid has extremely high use value. In addition, the invention further elaborates the preparation and application scenarios of the steel fracture cleaning fluid in detail. When the steel fracture cleaning solution prepared by the invention is used for cleaning a steel fracture sample in a service state, the cleaning time can be remarkably shortened, and the cleaning efficiency is improved. And after processing, a fracture observation surface with a large-area oxide layer effectively removed can be obtained, so that the real morphology of the steel fracture is precisely reduced, related information of corrosion components of the steel fracture is obtained, and reliable basic data is provided for subsequent steel performance evaluation and failure analysis.

Description

Technical Field

[0001] This invention relates to the field of fracture failure analysis technology, specifically to a steel fracture cleaning fluid, its preparation method, and its application. Background Technology

[0002] Fracture surface analysis is a core technology for revealing the causes of steel material failure in coal-fired power plants. Steel components in equipment such as boilers and turbines are subjected to multiple effects over long periods, including high temperature, high pressure, alternating stress, and corrosive media. Fracture failure can lead to serious safety accidents and economic losses. Fracture surface analysis allows for the direct identification of fracture types, such as cleavage surfaces in brittle fracture, dimples in ductile fracture, and fatigue striations in fatigue fracture. These microscopic features enable precise determination of the fracture mechanism, providing crucial information for tracing equipment failures and preventing accidents. Furthermore, the results of fracture surface analysis can guide the selection and optimization of steel materials and process improvements, enhancing the service performance of materials from the source and strengthening the safety and reliability of power generation equipment.

[0003] Fracture surface cleaning, as a crucial preliminary step in fracture analysis, is of paramount importance. In actual operating conditions, the fracture surfaces of steel materials in coal-fired power plants are typically covered with impurities such as oxide scale, corrosion products, and oil. These substances severely interfere with the observation and analysis of the true morphology and composition of the fracture surface, leading to misjudgments of the failure mode. Effective fracture surface cleaning techniques, combined with physical or chemical methods, can precisely remove surface contaminants, clearly revealing key failure characteristics such as fatigue striations, river patterns, intergranular structures, and dimples, laying the foundation for accurate identification of failure modes and mechanisms. Furthermore, cleaned fracture surfaces are more conducive to the application of compositional analysis techniques such as energy dispersive spectroscopy and electron probe microanalysis, helping to determine information such as changes in material composition and the composition of corrosion products, providing strong support for a comprehensive analysis of the causes of failure. Therefore, high-quality fracture surface cleaning is not only a prerequisite for obtaining reliable analytical data but also a vital guarantee for ensuring the safe and stable operation of coal-fired power generation equipment.

[0004] However, common methods for cleaning fracture surfaces, such as immediately placing fresh fracture surfaces in a desiccator or vacuum chamber to prevent rusting after fracture in a dry atmosphere; removing oil contamination with gasoline, then dissolving residues with organic solvents, and finally rinsing with anhydrous ethanol and drying; and removing rust oxides with dilute hydrochloric acid solution, followed by rinsing with water and anhydrous ethanol and drying, generally lack detailed processing steps and systematic procedures. These methods are not conducive to fracture surface treatment and may even lead to secondary corrosion due to inaccurate control.

[0005] Therefore, it is of great significance to develop a cleaning method that does not damage the original fracture morphology, can effectively remove the corrosion layer of the fracture, and is efficient and time-saving. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a steel fracture surface cleaning fluid, its preparation method, and its application. The fracture surface cleaning fluid of the present invention is simple, readily available, and low in cost. The present invention also provides the preparation and application of the steel fracture surface cleaning fluid. Using the steel fracture surface cleaning fluid prepared according to the present invention to clean the fracture surfaces of service-ready steel samples results in short cleaning time, high efficiency, and the acquisition of a large area of ​​fracture surface with removed oxide layer, enabling the acquisition of true steel fracture morphology and corrosion composition information.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: The first objective of this invention is a steel fracture surface cleaning fluid, which comprises the following components: citric acid, hydrochloric acid, glycerol, corrosion inhibitor, and water.

[0008] The beneficial effects of this invention are: (1) Hydrochloric acid is an inorganic strong acid that can continuously react chemically with the oxide layer and rust on the fracture surface, dissolving and removing them, thereby exposing the true morphology of the fracture surface, which is convenient for subsequent observation and analysis. However, hydrochloric acid can also dissolve the metal matrix. Citric acid is an organic acid with mild acidity and complexing ability, which can form stable complexes with metal ions. Therefore, when cleaning the fracture surface, adding citric acid can dissolve some metal oxides, while the corrosive effect on the metal matrix is ​​relatively small.

[0009] (2) To further protect the metal substrate, glycerol and corrosion inhibitors were added to the fracture cleaning solution. Glycerol has wettability and penetrability; on the one hand, it can penetrate into the oxide layer, which is conducive to the removal of oxide scale; on the other hand, it has a certain protective effect on the metal substrate. Corrosion inhibitors are substances that inhibit metal corrosion. During fracture cleaning, when hydrochloric acid and citric acid remove the oxide layer on the fracture surface, a protective film is formed on the metal surface, preventing further reaction between the acid and the metal substrate, thereby reducing corrosion of the steel fracture surface, protecting the fracture microstructure from damage, and ensuring that the cleaning process effectively removes impurities without affecting subsequent analysis and research of the fracture surface.

[0010] (3) In this invention, fracture cleaning is performed on the fracture surface of steel samples in service state to obtain a fracture observation surface in which the oxide layer is removed over a large area, thereby obtaining the true fracture morphology and corrosion composition information. Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the ratio of citric acid, hydrochloric acid, glycerol, corrosion inhibitor, and water is 13.32 g~19.98 g: 0.5 mL~1 mL: 5 mL: 0.3 mL; wherein the mass concentration of hydrochloric acid is 36.0%~38.0%.

[0012] Furthermore, the corrosion inhibitor includes at least one of LAN-826, hexamethylenetetramine, and thiourea.

[0013] The beneficial effects of adopting the above-mentioned further scheme are as follows: corrosion inhibitors are substances that inhibit metal corrosion. During fracture cleaning, when hydrochloric acid and citric acid remove the oxide layer on the fracture surface, a protective film is formed on the metal surface, preventing further reaction between the acid and the metal matrix, thereby reducing corrosion of the steel fracture surface, protecting the fracture surface microstructure from damage, and ensuring that the cleaning process effectively removes impurities without affecting subsequent analysis and research on the fracture surface.

[0014] The second objective of this invention is a method for preparing a steel fracture surface cleaning fluid, as detailed below: Citric acid, hydrochloric acid, glycerol, and corrosion inhibitor are added to water in sequence and stirred until homogeneous to obtain the fracture cleaning solution.

[0015] The beneficial effects of this invention are: the fracture cleaning fluid of this invention is simple and readily available, low in cost, and has a short cleaning time and high efficiency.

[0016] The third objective of this invention is the application of a steel fracture cleaning fluid, which is used to clean steel fracture surfaces.

[0017] The beneficial effects of this invention are: using the steel fracture cleaning fluid prepared by this invention to clean the fracture surface of steel in service not only does not damage the original fracture morphology, but also effectively removes the oxide layer of the fracture surface and has high safety.

[0018] The fourth objective of this invention is to provide a method for cleaning the fracture surface of steel, comprising the following steps: (1) The steel fracture surface is first cleaned using an organic solvent to obtain the steel fracture surface after the first cleaning; (2) The fracture surface after the first cleaning is immersed in steel fracture cleaning solution for a second cleaning to obtain the fracture surface after the second cleaning; (3) Clean the steel fracture surface after the second cleaning with alcohol and then dry it to complete the cleaning of the steel fracture surface.

[0019] The advantages of this invention are: it has a short cleaning time and high efficiency.

[0020] Furthermore, the organic solvent is at least one of acetone, alcohol, and kerosene.

[0021] The beneficial effect of adopting the above-mentioned further solution is that it removes surface oil stains using organic solvents.

[0022] Furthermore, the first cleaning time is 5 to 10 minutes; the second cleaning time is 2 to 30 minutes; the alcohol cleaning is performed 1 to 3 times, with a time of 1 to 3 minutes.

[0023] The beneficial effects of adopting the above-mentioned further solutions are: the present invention adopts different fracture cleaning procedures for service-state steel fracture samples with different materials, temperatures, pressures and durations, to obtain fracture observation surfaces with large-area removal of oxide layers, and to obtain true fracture morphology and corrosion composition information.

[0024] Furthermore, in step (3), after cleaning and drying, a mixture is applied to the surface of the steel pipe break; the mixture consists of powder and liquid; the weight ratio of the powder to the liquid is 2~3:1.

[0025] The beneficial effects of the above-mentioned further solution are as follows: The mixture of powder and liquid coating, after solidification, can isolate air, water, and external corrosive media from penetrating the fracture surface cracks, thus preventing corrosion. Simultaneously, the thermal expansion and contraction during the solidification process (40℃~60℃) allows the mixture to adhere to the oxide film on the fracture surface, reducing the adhesion between the oxide film and the metal substrate. This facilitates further removal of the oxide scale from the fracture surface, and subsequent observation only requires ultrasonic cleaning with acetone to remove the protective resin. This method allows for long-term sample preservation and convenient multiple characterization analyses over several months.

[0026] Furthermore, the powder comprises polymethyl methacrylate, benzoyl peroxide, and pigment; the weight ratio of polymethyl methacrylate, benzoyl peroxide, and pigment is 92~97:0.5~3:2~5.

[0027] The liquid comprises methyl methacrylate, N,N-dihydroxypropyl-p-toluidine, and 2,6-di-tert-butyl-4-methylphenol; the volume ratio of methyl methacrylate, N,N-dihydroxypropyl-p-toluidine, and 2,6-di-tert-butyl-4-methylphenol is 97~99.5:0.3~0.6:0.01~0.1.

[0028] Furthermore, the weight ratio of the polymethyl methacrylate, the benzoyl peroxide, and the pigment is 95:1:4; the volume ratio of the methyl methacrylate, the N,N-dihydroxypropyl-p-toluidine, and the 2,6-di-tert-butyl-4-methylphenol is 99.4:0.55:0.05. Attached Figure Description

[0029] Figure 1The images show the fracture morphology and oxygen distribution of the 15CrMoG water-cooled wall tube sample in Example 4 of this invention; (a) shows the fracture morphology of the 15CrMoG water-cooled wall tube sample before fracture cleaning; (b) shows the oxygen distribution of the 15CrMoG water-cooled wall tube sample before fracture cleaning; (c) shows the fracture morphology of the 15CrMoG water-cooled wall tube sample after fracture cleaning; and (d) shows the oxygen distribution of the 15CrMoG water-cooled wall tube sample after fracture cleaning. Figure 2 The images show the fracture morphology, oxygen distribution, and corrosion products under the oxide layer of a cracked sample during the welding repair process of a T12 water-cooled wall tube in Embodiment 5 of the present invention; wherein (a) is the fracture morphology of the T12 water-cooled wall tube sample before fracture cleaning; (b) is the oxygen distribution of the T12 water-cooled wall tube before fracture cleaning; (c) is the fracture morphology of the T12 water-cooled wall tube after fracture cleaning; (d) is the oxygen distribution of the T12 water-cooled wall tube after fracture cleaning; (e) is the morphology of the corrosion products under the oxide layer of the T12 water-cooled wall tube before fracture cleaning; and (f) is the sulfur distribution of the corrosion products under the oxide layer of the T12 water-cooled wall tube after fracture cleaning. Figure 3 The images show the fracture morphology and oxygen distribution of the cracked TP347H main steam pipe drain pipe sample from Embodiment 6 of the present invention; (a) is the fracture morphology of the cracked TP347H main steam pipe drain pipe sample before fracture cleaning; (b) is the oxygen distribution of the cracked TP347H main steam pipe drain pipe sample before fracture cleaning; (c) is the fracture morphology of the cracked TP347H main steam pipe drain pipe sample after fracture cleaning; and (d) is the oxygen distribution of the cracked TP347H main steam pipe drain pipe sample after fracture cleaning. Figure 4 After cleaning and observing the fracture surface of the TP347H main steam pipe drain pipe in Example 7 of this invention, a mixed solution was coated on the surface and stored after solidification. Two weeks later, the surface was cleaned again and the fracture morphology and oxygen element distribution were analyzed again. Among them, (a) is the morphology of the fracture surface of the TP347H main steam pipe drain pipe after cleaning again; (b) is the oxygen element distribution of the fracture surface of the TP347H main steam pipe drain pipe after cleaning again. Figure 5 The fracture morphology and oxygen distribution of the 15CrMoG water-cooled wall tube sample in Comparative Example 1 of the present invention are shown in Figure 1. (a) is the fracture morphology of the 15CrMoG water-cooled wall tube sample after fracture cleaning; (b) is the oxygen distribution of the 15CrMoG water-cooled wall tube sample after fracture cleaning. Figure 6The fracture morphology and oxygen distribution of the main steam pipe drain tube TP347H cracked sample in Comparative Example 2 of the present invention are shown in Figure (a), which is the fracture morphology of the main steam pipe drain tube TP347H cracked sample after fracture cleaning; and Figure (b) is the oxygen distribution of the main steam pipe drain tube TP347H cracked sample after fracture cleaning. Detailed Implementation

[0030] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0031] Example 1: Preparation of steel fracture surface cleaning fluid Citric acid, hydrochloric acid, glycerol, and corrosion inhibitor were added sequentially to deionized water and stirred until homogeneous to obtain the fracture cleaning solution. Each 100 mL of the cleaning solution contained 13.32 g of analytical grade citric acid, 0.5 mL of analytical grade hydrochloric acid (36.0%–38.0% mass concentration), 5 mL of analytical grade glycerol, 0.3 mL of corrosion inhibitor LAN-826 (Lanzhou Lanxing), and the remainder was deionized water.

[0032] Example 2: Preparation of Steel Fracture Surface Cleaning Fluid Citric acid, hydrochloric acid, glycerol, and corrosion inhibitor were added sequentially to deionized water and stirred until homogeneous to obtain the fracture cleaning solution. Each 100 mL of the cleaning solution contained 16.65 g of analytical grade citric acid, 0.8 mL of analytical grade hydrochloric acid (36.0%–38.0% mass concentration), 5 mL of analytical grade glycerol, 0.3 mL of corrosion inhibitor LAN-826 (Lanzhou Lanxing), and the remainder was deionized water.

[0033] Example 3: Preparation of Steel Fracture Surface Cleaning Fluid Citric acid, hydrochloric acid, glycerol, and corrosion inhibitor were added sequentially to deionized water and stirred until homogeneous to obtain the fracture cleaning solution. Each 100 mL of the cleaning solution contained 19.98 g of analytical grade citric acid, 1 mL of analytical grade hydrochloric acid (36.0%–38.0% mass concentration), 5 mL of analytical grade glycerol, 0.3 mL of corrosion inhibitor LAN-826 (Lanzhou Lanxing), and the remainder was deionized water.

[0034] Example 4: Cleaning of steel pipe fracture ends In this embodiment, the steel pipe material is 15CrMoG pipe for the water-cooled wall of power plant A (served for 9 years, with a service temperature of approximately 350℃~500℃, and the base material has cracked). The cleaning method includes the following steps: (1) Under the emulsion cooling condition, use an electric spark wire cutting device (DK7750T; Jiangsu Fangzheng CNC Machine Tool Co., Ltd.) to cut a small sample near the fracture of the 15CrMoG pipe. The vertical height of the fracture from both ends should not exceed 23 mm to ensure that the cutting position does not damage the front edge of the fracture. Clean the fracture of the 15CrMoG pipe with acetone ultrasonically to remove surface oil. Use pliers to hold one end of the 15CrMoG pipe fracture and use pliers to hold the other end of the 15CrMoG pipe fracture. Open the 15CrMoG pipe fracture along the direction of the crack propagation. Ensure that the fracture surface is not damaged during the process of opening the 15CrMoG pipe fracture to obtain the 15CrMoG pipe fracture sample. (2) Add 100 mL of the steel fracture cleaning solution prepared in Example 1 into a beaker so that the steel fracture cleaning solution can submerge the 15CrMoG pipe fracture sample. Use an ultrasonic cleaner (KQ5200E; Kunshan Ultrasonic Instrument Co., Ltd.) to ultrasonically clean at 40kHz and 200W for 5 min, brush the fracture surface with a soft brush for 1 min, and ultrasonically clean the fracture twice with alcohol at 40kHz and 200W for 2 min each time. Then blow dry at low temperature to obtain the cleaned 15CrMoG pipe fracture sample. (3) The cleaned 15CrMoG pipe fracture sample was placed in a Zeiss EVO10 scanning electron microscope equipped with an Oxford Xplore 30 energy dispersive spectrometer to observe the fracture morphology. Energy dispersive spectroscopy analysis was performed on different morphological regions of the fracture to analyze the removal of the oxide layer. Figure 1 As shown, some of the large pieces of oxide scale on the fracture surface have been removed.

[0035] Example 5: Cleaning of Steel Pipe Fracture Threads (Part 2) In this embodiment, the steel pipe material is T12 pipe for the B water-cooled wall of a power plant (18 years of service, the weld at the repair weld after thinning due to corrosion of the pipe wall has cracked). The cleaning method includes the following steps: (1) Under the emulsion cooling condition, use an electric spark wire cutting device (DK7750T; Jiangsu Fangzheng CNC Machine Tool Co., Ltd.) to cut a small sample near the fracture of the T12 pipe. The vertical height of the fracture from both ends should not exceed 20mm to ensure that the cutting position does not damage the expansion front of the fracture. Clean the fracture of the T12 pipe with acetone ultrasonically to remove surface oil. Use pliers to clamp one end of the fracture of the T12 pipe and use a hammer to hammer the other end of the fracture of the T12 pipe. Open the fracture of the T12 pipe along the direction of crack expansion of the fracture, and ensure that the fracture surface is not damaged during the process of opening the fracture of the T12 pipe to obtain the fracture sample of the T12 pipe. (2) Add 100 mL of steel fracture cleaning solution prepared in Example 2 into a beaker so that the steel fracture cleaning solution can submerge the T12 pipe fracture sample. Use an ultrasonic cleaner (KQ5200E; Kunshan Ultrasonic Instrument Co., Ltd.) to clean for 2 min at 40 kHz and 200 W, brush the fracture surface with a soft brush for 1 min, and use alcohol to ultrasonically clean the fracture 3 times at 40 kHz and 200 W for 2 min each time. Then blow dry at low temperature to obtain the cleaned T12 pipe fracture sample. (3) The cleaned T12 pipe fracture sample was placed in a Zeiss EVO10 scanning electron microscope equipped with an Oxford Xplore30 energy dispersive spectrometer to observe the fracture morphology. Energy dispersive spectroscopy analysis was performed on different morphological regions of the fracture to analyze the removal of the oxide layer. Figure 2 As shown, some of the oxide scale on the fracture surface has been removed. Underneath the oxide scale are low-melting-point compounds FeS and MnS formed by sulfate corrosion products during the welding process. These low-melting-point compounds exist in the form of a liquid film at the grain boundaries during the welding cooling process, which weakens the grain boundary bonding force. Under the action of thermal stress or external force, they become the initiation point of cracks.

[0036] Example 6: Cleaning of Steel Pipe Fracture Threads (Part 3) In this embodiment, the steel pipe material is TP347H pipe for the main steam pipeline drain pipe of power plant C (served for 2 years, with a pipe wall service temperature of 500℃~650℃, and multiple cracks in the base material). The cleaning method includes the following steps: (1) Under the emulsion cooling condition, use an electric spark wire cutting device (DK7750T; Jiangsu Fangzheng CNC Machine Tool Co., Ltd.) to cut a small sample near the fracture of TP347H pipe. The vertical height of the fracture from both ends should not exceed 23 mm to ensure that the cutting position does not damage the front edge of the fracture. Clean the fracture of TP347H pipe with acetone ultrasonic organic cleaner to remove surface oil. Use pliers to hold one end of the fracture of TP347H pipe and use pliers to hold the other end of the fracture of TP347H pipe. Open the fracture of TP347H pipe along the direction of crack propagation. Ensure that the fracture surface is not damaged during the process of opening the fracture of TP347H pipe to obtain the fracture sample of TP347H pipe. (2) Add 100 mL of the steel fracture cleaning solution prepared in Example 3 into a beaker so that the steel fracture cleaning solution can submerge the TP347H pipe fracture sample. Use an ultrasonic cleaner (KQ5200E; Kunshan Ultrasonic Instrument Co., Ltd.) to ultrasonically clean at 40 kHz and 200 W for 30 min, brush the fracture surface with a soft brush for 1 min, and use alcohol to ultrasonically clean the fracture 3 times at 40 kHz and 200 W for 2 min each time. Then blow dry at low temperature to obtain the cleaned TP347H pipe fracture sample. (3) The cleaned TP347H pipe fracture sample was placed in a Zeiss EVO10 scanning electron microscope equipped with an Oxford Xplore 30 energy dispersive spectrometer to observe the fracture morphology and perform energy dispersive spectroscopy analysis on different morphological regions of the fracture. Figure 3 As shown, the oxide layer on the stainless steel fracture surface is relatively thick and tightly bonded to the substrate. Some small areas of oxide scale can be removed, and fatigue striations can be observed in some areas.

[0037] Example 7: Cleaning of Steel Pipe Breaks (Part 4) (1) After scanning electron microscopy and energy dispersive spectroscopy analysis of the cleaned TP347H pipe fracture sample in Example 6, a mixture of powder and liquid was prepared in a weight ratio of 2:1. The powder contained 95% polymethyl methacrylate, 1% benzoyl peroxide, and 4% pigment. The liquid contained 99.4% methyl methacrylate, 0.55% N,N-dihydroxypropyl p-toluidine, and 0.05% 2,6-di-tert-butyl-4-methylphenol. The mixture was brushed onto the surface of the TP347H pipe fracture sample. The mixture solidified after 30 min. During the solidification process, heat was released, and the temperature could reach 40℃~60℃. After solidification, the temperature returned to room temperature. During this process, because the resin adhered to the oxide scale of the fracture, the bonding force between the oxide scale and the metal matrix was reduced under the action of thermal expansion and contraction. (2) After coating the oxidized fracture surface of TP347H with a mixture of powder and liquid, it was stored in a solidified state for 2 weeks. When the fracture characteristics were confirmed again by scanning electron microscopy for analysis, the sample was placed in a beaker, and analytical grade acetone was poured in to completely immerse the sample. The sample was then cleaned in an ultrasonic cleaner for 10 min to 30 min. (3) Acetone has a dissolving effect on resin. Every 10 minutes of cleaning, use a soft brush to remove some of the resin and oxide scale from the fracture surface; repeat this 2 to 3 times.

[0038] The cleaned fracture surface was observed under a scanning electron microscope. Figure 4 As shown, the oxide scale was further removed, and the bond between the oxide scale and the substrate became loose in some areas.

[0039] Comparative Example 1: Cleaning of Steel Pipe Fracture Surface The conditions and steps of this comparative example are exactly the same as those of Example 4. The only difference is the steel cleaning solution. In the 100 mL cleaning solution used in this comparative example, there is 1 g of analytical grade citric acid, 0.5 mL of analytical grade hydrochloric acid with a mass concentration of 36.0%~38.0%, 5 mL of analytical grade glycerol, 0.3 mL of corrosion inhibitor LAN-826 (Lanzhou Lanxing), and the remainder is deionized water.

[0040] The cleaned 15CrMoG pipe fracture samples were placed in a Zeiss EVO10 scanning electron microscope equipped with an Oxford Xplore 30 energy dispersive spectrometer to observe the fracture morphology. Energy dispersive spectroscopy analysis was performed on different morphological regions of the fracture to analyze the removal of the oxide layer. Figure 5 As shown, cracks appeared in some areas of the oxide film on the fracture surface, and the area of ​​oxide scale removal was relatively small.

[0041] Comparative Example 2: Cleaning of Steel Pipe Fracture Surface The conditions and steps of this comparative example are exactly the same as those of Example 6, except that the cleaning time in step (1) is different. Step (1) is as follows: (1) Add 100 mL of the steel fracture cleaning solution prepared in Example 3 into a beaker so that the steel fracture cleaning solution can submerge the TP347H pipe fracture sample. Use an ultrasonic cleaner (KQ5200E; Kunshan Ultrasonic Instrument Co., Ltd.) to ultrasonically clean at 40 kHz and 200 W for 5 min, brush the fracture surface with a soft brush for 1 min, and ultrasonically clean the fracture three times with alcohol at 40 kHz and 200 W for 2 min each time. Then blow dry at low temperature to obtain the cleaned TP347H pipe fracture sample.

[0042] The cleaned TP347H pipe fracture sample was placed in a Zeiss EVO10 scanning electron microscope equipped with an Oxford Xplore 30 energy dispersive spectrometer to observe the fracture morphology. Energy dispersive spectroscopy analysis was performed on different morphological regions of the fracture. Figure 6 As shown, the oxide scale on the stainless steel fracture surface was not significantly removed.

[0043] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A steel fracture surface cleaning fluid, characterized in that, The fracture cleaning fluid includes the following components: citric acid, hydrochloric acid, glycerol, corrosion inhibitor, and water.

2. The steel fracture surface cleaning fluid according to claim 1, characterized in that, The ratio of citric acid, hydrochloric acid, glycerol, corrosion inhibitor, and water is 13.32 g to 19.98 g: 0.5 mL to 1 mL: 5 mL: 0.3 mL; wherein the mass concentration of hydrochloric acid is 36.0% to 38.0%.

3. The steel fracture surface cleaning fluid according to claim 1, characterized in that, The corrosion inhibitor includes at least one of LAN-826, hexamethylenetetramine, and thiourea.

4. A method for preparing a steel fracture surface cleaning fluid according to any one of claims 1 to 3, characterized in that, The specific preparation method is as follows: Citric acid, hydrochloric acid, glycerol, and corrosion inhibitor are added to water in sequence and stirred evenly to obtain a steel fracture cleaning solution.

5. An application of a steel fracture surface cleaning fluid, characterized in that, The fracture cleaning fluid according to any one of claims 1 to 3 is used for cleaning the fracture surfaces of steel.

6. A method for cleaning the fracture surface of steel, characterized in that, Includes the following steps: (1) The steel fracture surface is first cleaned with an organic solvent to obtain the steel fracture surface after the first cleaning; (2) The fracture surface after the first cleaning is immersed in the steel fracture surface cleaning solution as described in any one of claims 1 to 3 for a second cleaning to obtain the fracture surface after the second cleaning; (3) Clean the steel fracture surface after the second cleaning with alcohol and then dry it to complete the cleaning of the steel fracture surface.

7. The method for cleaning the fracture surface of steel according to claim 6, characterized in that, The organic solvent is at least one of acetone, alcohol, and kerosene.

8. The method for cleaning the fracture surface of steel according to claim 6, characterized in that, The first cleaning takes 5 to 10 minutes; the second cleaning takes 2 to 30 minutes, and the second cleaning is performed 1 to 3 times, with a time of 1 to 3 minutes.

9. A method for cleaning the fracture surface of steel according to claim 6, characterized in that, Step (3) After cleaning and drying, a mixture is applied to the surface of the steel pipe break. The mixture consists of powder and liquid. The weight ratio of the powder to the liquid is 2 to 3:

1.

10. A method for cleaning the fracture surface of steel according to claim 9, characterized in that, The powder comprises polymethyl methacrylate, benzoyl peroxide, and pigment; the weight ratio of polymethyl methacrylate, benzoyl peroxide, and pigment is 92~97:0.5~3:2~5. The liquid comprises methyl methacrylate, N,N-dihydroxypropyl-p-toluidine, and 2,6-di-tert-butyl-4-methylphenol; the volume ratio of methyl methacrylate, N,N-dihydroxypropyl-p-toluidine, and 2,6-di-tert-butyl-4-methylphenol is 97~99.5:0.3~0.6:0.01~0.1.

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