Electrolyte composition, electrochemical in-situ etching method of non-metallic inclusions for heavy rail steel and application of electrochemical in-situ etching method

Abstract

The invention provides an electrolyte composition, an electrochemical in-situ etching method of non-metallic inclusions for heavy rail steel and application of the electrochemical in-situ etching method. The electrolyte composition comprises the following components in parts by weight: 1.6 to 2.3 parts of lithium chloride, 10 to 13.5 parts of acetylacetone, 45 to 84 parts of methanol and 2 to 43 parts of a reagent A, the reagent A is a mixed aqueous solution of ethylenediamine tetraacetic acid and sodium citrate. The lithium chloride, the acetylacetone, the methanol and the reagent A in specific parts are matched for use, the obtained electrolyte composition is used for in-situ electrochemical etching of the heavy rail steel, and three-dimensional in-situ etching of the non-metallic inclusions in the heavy rail steel can be successfully achieved. The in-situ information of the non-metallic inclusions in the hypereutectoid heavy rail steel is reserved, and the three-dimensional morphology of the non-metallic inclusions can be presented more comprehensively.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting technology, specifically to an electrolyte composition, an electrochemical in-situ etching method for non-metallic inclusions in heavy rail steel, and its application. Background Technology

[0002] As a key component of railway transportation, rails affect the speed, efficiency, and safety of railway operations. Currently, with the continuous development of railway transportation, the quality requirements for rails are becoming increasingly stringent. Non-metallic inclusions in rails disrupt the continuity of the matrix structure. As heterogeneous phases, once they reach a certain size, they can easily deteriorate the mechanical properties of the rails and are considered an important quality indicator for rail testing. For example, hard Al2O3 can worsen the plasticity, toughness, and fatigue resistance of rails, easily causing spalling and flaking. Large-sized MnS inclusions can cause corrosion, and since MnS is a ductile inclusion, it easily deforms into elongated MnS inclusions during rolling. These elongated MnS inclusions can increase or even exceed the Class A inclusion rating and lead to failure in ultrasonic testing. Therefore, controlling non-metallic inclusions is crucial for rails, an important component of railway transportation.

[0003] As is well known, the study of non-metallic inclusions in steel requires theoretical research from thermodynamic and kinetic perspectives, as well as industrial trials closely integrated with on-site equipment and process conditions to precisely adjust the actual production process. In the precise adjustment of the actual production process, comprehensive and accurate analysis of industrial trial results is crucial for process research. Generally, incomplete or inaccurate test results often lead to inaccurate production process research, or even misjudgments, making it difficult to achieve effective breakthroughs in related process research. Therefore, the study of non-metallic inclusions in heavy rail steel requires comprehensive and accurate detection of non-metallic inclusions.

[0004] Currently, research on non-metallic inclusions in heavy rail steel mainly focuses on inclusion control processes and equipment technology. For the detection of non-metallic inclusions, most methods employ two-dimensional or three-dimensional detection, including metallographic analysis, large-sample electrolysis, Aspex scanning statistics, and industrial CT scanning. Two-dimensional detection often struggles to obtain complete inclusion morphology, and may even result in significant loss of observational information and chemical composition data for some inclusions. Furthermore, due to the complex formation process of non-metallic inclusions in steel, some inclusions evolve layer by layer at different stages, leading to deviations in chemical composition detection results from two-dimensional detection, ultimately resulting in misjudgments of inclusion origins and their formation and evolution mechanisms. Three-dimensional detection primarily employs electrolytic methods, including partial acid etching, small-sample electrolysis, and large-sample electrolysis. These techniques provide more comprehensive inclusion information compared to two-dimensional detection; however, different steel grades exhibit varying degrees of acid corrosion resistance due to differences in chemical composition, resulting in highly inconsistent detection outcomes. In addition, in-situ information of inclusions is crucial for inclusion research, but current methods are unable to detect in-situ information. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide an electrolyte composition, an electrochemical in-situ etching method for non-metallic inclusions in heavy rail steel, and its application. This invention uses the aforementioned electrolyte composition for electrochemical in-situ etching, which not only preserves the in-situ information of non-metallic inclusions in hypereutectoid heavy rail steel, but also more comprehensively presents the three-dimensional morphology of the non-metallic inclusions, allowing for a more comprehensive analysis of the composition and content information of the non-metallic inclusions.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an electrolyte composition comprising, by weight: 1.6 to 2.3 parts lithium chloride, 10 to 13.5 parts acetylacetone, 45 to 84 parts methanol, and 2 to 43 parts reagent A;

[0008] Reagent A is a mixed aqueous solution of ethylenediaminetetraacetic acid and sodium citrate.

[0009] Preferably, the mass fraction of sodium citrate in reagent A is 5%, and the mass fraction of ethylenediaminetetraacetic acid is 5%.

[0010] Preferably, the pH of the electrolyte composition is 7.8 to 8.2.

[0011] Preferably, the formulation of the electrolyte composition is selected from any one of the following:

[0012] 1.6% lithium chloride, 10.4% acetylacetone, 45% methanol, 43% reagent A;

[0013] Alternatively, use 2% lithium chloride, 12.5% ​​acetylacetone, 70% methanol, and 15.5% reagent A;

[0014] Or 2.3% lithium chloride, 10% acetylacetone, 84% methanol, 3.7% reagent A;

[0015] Or 1.8% lithium chloride, 13.5% acetylacetone, 70% methanol, 14.7% reagent A;

[0016] Alternatively, use 2% lithium chloride, 12% acetylacetone, 84% methanol, and 2% reagent A.

[0017] Secondly, the present invention provides an electrochemical in-situ etching method for non-metallic inclusions in heavy rail steel, comprising the following steps:

[0018] Electrochemical in-situ etching of heavy rail steel samples was performed using an electrolyte solution.

[0019] The electrolyte comprises the above-described electrolyte composition.

[0020] Preferably, the heavy rail steel sample consists of the following components by mass fraction:

[0021] C 0.65%~0.82%, Si 0.10%~0.80%, Mn 0.70%~1.20%, P≤0.025%, S≤0.025%, Cr0.0~0.50%, V 0.04%~0.12%, with the remainder being Fe and other unavoidable impurities.

[0022] Preferably, the non-metallic inclusions in the heavy rail steel sample include MnS and composite oxides of Ca, Si, Al, and Mg.

[0023] Preferably, the electrochemical in-situ etching temperature is -5 to -1°C, and the current density is 0.04 to 0.06 A / cm². 2 The time is 460~500 seconds.

[0024] Thirdly, the present invention provides a method for detecting non-metallic inclusions in heavy rail steel, comprising the following steps:

[0025] S1: Electrochemical in-situ etching of heavy rail steel samples was performed according to the above electrochemical in-situ etching method.

[0026] S2: After cleaning and drying the sample following electrochemical in-situ etching, metallographic inclusion detection is performed.

[0027] Preferably, the metallographic inclusion detection is performed using EBSD metallographic inclusion detection.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention provides an electrolyte composition for electrochemical in-situ etching of non-metallic inclusions in heavy rail steel, comprising 1.6-2.3 parts lithium chloride, 10-13.5 parts acetylacetone, 45-84 parts methanol, and 2-43 parts reagent A. Reagent A is a mixed aqueous solution of ethylenediaminetetraacetic acid (EDTA) and sodium citrate. EDT chelates the heavy rail steel matrix to protect acid-sensitive inclusions, while sodium citrate, a weak acid-strong base salt, resists drastic pH changes in the electrolyte. Simultaneously, lithium chloride accounts for 1.6%-2.3%, acetylacetone 10%-13.5%, and methanol 45%-84%. This invention, by using the specific proportions of lithium chloride (for conductive particles), acetylacetone (for complexation, altering electrolytic deposition, and maintaining reaction stability on the reaction surface), methanol (the solvent for the former two), and reagent A in combination, yields an electrolyte composition suitable for in-situ electrochemical etching of heavy rail steel, successfully achieving three-dimensional in-situ etching of non-metallic inclusions in heavy rail steel. Not only does it preserve the in-situ information of non-metallic inclusions in hypereutectoid heavy rail steel, it can also present the three-dimensional morphology of non-metallic inclusions more comprehensively. Furthermore, by combining it with conventional metallographic testing, it can more comprehensively analyze the composition and content information of non-metallic inclusions, providing important scientific basis for the analysis and research of non-metallic inclusions and the development of control technology. Attached Figure Description

[0030] Figure 1 The image shows the SEM image of the product obtained after post-processing of the sample in Example 1.

[0031] Figure 2 This is an SEM image of the product obtained after sample post-processing in Example 2;

[0032] Figure 3 Images showing the distribution of key chemical components in non-metallic inclusions obtained by EBSD scanning in Example 2;

[0033] Figure 4 The image shows the SEM image of the product obtained after post-processing of the sample in Example 3.

[0034] Figure 5 The image shows the SEM image of the product obtained after post-processing of the sample in Comparative Example 1. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] To address the problems existing in current methods for detecting non-metallic inclusions in heavy rail steel, this invention first provides an electrolyte composition comprising, by weight: 1.6-2.3 parts lithium chloride, 10-13.5 parts acetylacetone, 45-84 parts methanol, and 2-43 parts reagent A.

[0037] In this invention, lithium chloride (molecular formula LiCl, white crystals) in the electrolyte composition is used as a conductive particle, specifically including 1.6 to 2.3 parts of lithium chloride, such as 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2.0 parts, 2.1 parts, 2.2 parts, or 2.3 parts, etc.

[0038] In this invention, the acetylacetone in the electrolyte composition can play a complexing role, which is used to change the electrolytic deposition and maintain the reaction stability of the reaction surface. Specifically, it includes 10 to 13.5 parts of acetylacetone, such as 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts or 13.5 parts, etc.

[0039] In this invention, methanol in the electrolyte composition is used as a solvent, specifically including 45 to 84 parts of methanol, such as 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, or 84 parts, etc.

[0040] In this invention, the electrolyte composition further includes 2 to 43 parts of reagent A, specifically 2 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or 43 parts. In this invention, reagent A is a mixed aqueous solution of ethylenediaminetetraacetic acid (EDTA) and sodium citrate. EDTA chelates the heavy rail steel matrix to protect acid-sensitive inclusions, and sodium citrate, a weak acid-strong base salt, can resist drastic pH changes in the electrolyte.

[0041] In some embodiments of the present invention, the mass fraction of sodium citrate in reagent A is 5% to 10%, such as 5%, 6%, 7%, 8%, 9% or 10%; the mass fraction of ethylenediaminetetraacetic acid is 5% to 10%, such as 5%, 6%, 7%, 8%, 9% or 10%.

[0042] In this invention, the pH of the electrolyte composition is preferably 7.8 to 8.2, such as 7.8, 7.9, 8.0, 8.1, or 8.2. This is because inclusions in heavy rail steel are easily destroyed by electrochemical reactions under acidic solution conditions, while some acidic inclusions, such as silicates, are easily affected in a strongly alkaline electrolyte. Therefore, the pH of this invention is preferably 7.8 to 8.2.

[0043] In some specific embodiments of the present invention, the formulation of the electrolyte composition is selected from any of the following:

[0044] 1.6% lithium chloride, 10.4% acetylacetone, 45% methanol, 43% reagent A;

[0045] or

[0046] 2% lithium chloride, 12.5% ​​acetylacetone, 70% methanol, 15.5% reagent A;

[0047] or

[0048] 2.3% lithium chloride, 10% acetylacetone, 84% methanol, 3.7% reagent A;

[0049] or

[0050] 1.8% lithium chloride, 13.5% acetylacetone, 70% methanol, 14.7% reagent A;

[0051] or

[0052] 2% lithium chloride, 12% acetylacetone, 84% methanol, 2% reagent A.

[0053] In this invention, the components in the electrolyte composition work together in combination. If any component is replaced or deleted, or its content is arbitrarily changed, the erosion and exposure of inclusions will be unsatisfactory, that is, the inclusions will fall off or be insufficiently exposed.

[0054] Generally speaking, the alloy composition and content of steel significantly affect its corrosion resistance, and the characteristics of non-metallic inclusions in steel also need to be fully considered in order to better preserve information about inclusions. Therefore, in the electrochemical corrosion process, the formulation of electrochemical corrosion reagents and key electrolysis process parameters need to be scientifically developed. Furthermore, in-situ information about inclusions is extremely crucial for inclusion research; that is, it is necessary to maintain information about the in-situ distribution of inclusions.

[0055] Therefore, the present invention also provides an electrochemical in-situ etching method for non-metallic inclusions in heavy rail steel, comprising the following steps:

[0056] The heavy rail steel sample is obtained by electrochemical in-situ etching using an electrolyte comprising the above-mentioned electrolyte composition.

[0057] In this invention, the heavy rail steel sample, used as the corrosion test sample, consists of the following components by mass fraction:

[0058] C 0.65%~0.82%, Si 0.10%~0.80%, Mn 0.70%~1.20%, P≤0.025%, S≤0.025%, Cr0.0~0.50%, V 0.04%~0.12%, with the remainder being Fe and other unavoidable impurities.

[0059] In this invention, the non-metallic inclusions in the heavy rail steel sample include MnS and composite oxides of Ca, Si, Al and Mg.

[0060] In some embodiments of the present invention, it is preferred to use cutting equipment to make the heavy rail steel sample into a regular cube with a volume of 5 mm × 18 mm × 30 mm, and to successively polish the surface of the sample to be observed with 180, 280, 400, 800 and 1200 grit sandpaper, further polish with polishing paste, rinse with alcohol, blow dry, and set aside for use.

[0061] The dimensions of the cube and the grit of the sandpaper can be adjusted reasonably according to the actual situation.

[0062] In this invention, the equipment for electrochemical in-situ etching includes: a DC regulated power supply, a temperature control device, a platinum electrode, and an electrolytic cell.

[0063] In the process of electrochemical in-situ etching, the present invention preferably clamps the sample to be electrolyzed at the positive electrode of the power supply and further immerses the sample in the electrolyte.

[0064] In this invention, the temperature for the electrochemical in-situ etching is -5 to -1°C, such as -5°C, -4°C, -3°C, -2°C, or -1°C, and the current density is 0.04 to 0.06 A / cm². 2 For example, it could be 0.04 A / cm 2 0.05 A / cm 2 Or 0.06 A / cm 2 The time is 460~500 seconds, such as 460 seconds, 470 seconds, 480 seconds, 490 seconds or 500 seconds, etc.

[0065] After the above-mentioned electrochemical in-situ etching is completed, the present invention preferably cleans the sample with anhydrous ethanol, dries it in a drying oven, and then performs SEM observation, or performs subsequent detection.

[0066] This invention also provides a method for detecting non-metallic inclusions in heavy rail steel, comprising the following steps:

[0067] S1: Electrochemical in-situ etching of heavy rail steel samples was performed according to the above electrochemical in-situ etching method.

[0068] S2: After cleaning and drying the sample following electrochemical in-situ etching, metallographic inclusion detection is performed.

[0069] In this invention, the metallographic inclusion detection adopts EBSD metallographic inclusion detection, which can be carried out using conventional research and analysis techniques known to those skilled in the art, to obtain the morphological characteristics, size information and in-situ distribution evolution law of the inclusions.

[0070] In summary, the present invention provides a method for electrochemical in-situ etching, which features simple equipment, convenient operation, and significant results, successfully achieving three-dimensional in-situ etching of non-metallic inclusions in hypereutectoid heavy rail steel. This method not only preserves the in-situ information of non-metallic inclusions in hypereutectoid heavy rail steel and presents a more comprehensive three-dimensional morphology of the inclusions, but also, by combining it with conventional metallographic detection, can more comprehensively analyze the composition and content information of non-metallic inclusions, providing important scientific basis for the analysis and research of non-metallic inclusions and the development of control technology.

[0071] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention are all commercially available products.

[0072] Example 1

[0073] This example uses heavy rail steel produced by a certain enterprise. Its smelting chemical composition (mass percentage) consists of the following elements: C 0.65%~0.72%, Si 0.70%~0.80%, Mn 0.70%~0.80%, P≤0.025%, S≤0.025%, Cr 0.0~0.10%, V 0.08%~0.12%, with the remainder being Fe and other unavoidable impurities.

[0074] The key technical parameters involved in this embodiment are as follows:

[0075] (1) Equipment preparation, the key equipment components are: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0076] (2) Electrolyte preparation: 1.6% lithium chloride, 10.4% acetylacetone, 45% methanol and 43% reagent A, wherein reagent A is a mixed aqueous solution of sodium citrate and ethylenediaminetetraacetic acid, and the mass fraction of sodium citrate and ethylenediaminetetraacetic acid in the aqueous solution is 5%. The initial pH value of the resulting electrolyte is 8.0.

[0077] (3) Sample preparation: The sample is made into a regular cube with a volume of 5 mm × 18 mm × 30 mm using cutting equipment. The surface of the sample to be observed is polished with 180, 280, 400, 800 and 1200 grit sandpaper in sequence. After further polishing with polishing paste, it is rinsed with alcohol and dried before electrochemical leaching.

[0078] (4) In-situ etching of non-metallic inclusions in the sample, etching environment (electrolyte) temperature -5~-2℃, current density i=0.05 A / cm 2 The leaching time was t = 480 ± 20 s.

[0079] (5) Sample post-treatment: The samples were cleaned with anhydrous ethanol and dried in a drying oven. The obtained samples were then observed by SEM. The results are as follows: Figure 1 As shown.

[0080] Furthermore, this embodiment can be supplemented by conventional research and analysis using EBSD metallographic inclusion detection to understand the morphological characteristics, size information, and in-situ distribution evolution of inclusions in the sample.

[0081] Example 2

[0082] This example uses heavy rail steel produced by a certain enterprise. Its smelting chemical composition (mass percentage) consists of the following elements: C 0.75%~0.82%, Si 0.10%~0.40%, Mn 0.90%~1.20%, P≤0.025%, S≤0.025%, Cr 0.40~0.50%, V 0.04%~0.06%, with the remainder being Fe and other unavoidable impurities.

[0083] The key technical parameters involved in this embodiment are as follows:

[0084] (1) Equipment preparation, the key equipment components are: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0085] (2) Electrolyte preparation: 2.0% lithium chloride, 12.5% ​​acetylacetone, 70% methanol and 15.5% reagent A, wherein reagent A is a mixed aqueous solution of sodium citrate and ethylenediaminetetraacetic acid, and the mass fraction of sodium citrate and ethylenediaminetetraacetic acid in the aqueous solution is 5%. The initial pH value of the obtained electrolyte is 7.8.

[0086] (3) Sample preparation: The sample is made into a regular cube with a volume of 5 mm × 18 mm × 30 mm using cutting equipment. The surface of the sample to be observed is polished with 180, 280, 400, 800 and 1200 grit sandpaper in sequence. After further polishing with polishing paste, it is rinsed with alcohol and dried before electrochemical leaching.

[0087] (4) In-situ etching of non-metallic inclusions in the sample, etching environment (electrolyte) temperature -4~-1℃, current density i=0.05 A / cm 2 The leaching time was t = 480 ± 15 s.

[0088] (5) Sample post-treatment: The samples were cleaned with anhydrous ethanol and dried in a drying oven. The obtained samples were then observed by SEM. The results are as follows: Figure 2 As shown.

[0089] Furthermore, this embodiment supplements conventional research and analysis using EBSD metallographic inclusion detection to understand the morphological characteristics, size information, and in-situ distribution evolution of inclusions in the sample. The results are as follows: Figure 3 As shown.

[0090] Example 3

[0091] This example is heavy rail steel produced by a certain enterprise. Its smelting chemical composition (mass percentage) consists of the following elements: C 0.70%~0.76%, Si 0.40%~0.60%, Mn 0.750%~0.90%, P≤0.025%, S≤0.025%, Cr 0.30~0.40%, V 0.07%~0.08%, with the remainder being Fe and other unavoidable impurities.

[0092] The key technical parameters involved in this embodiment are as follows:

[0093] (1) Equipment preparation, the key equipment components are: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0094] (2) Electrolyte preparation: 2.3% lithium chloride, 10% acetylacetone, 84% methanol and 3.7% reagent A. The initial pH of the resulting electrolyte is 8.2.

[0095] (3) Sample preparation: The sample is made into a regular cube with a volume of 5 mm × 18 mm × 30 mm using cutting equipment. The surface of the sample to be observed is polished with 180, 280, 400, 800 and 1200 grit sandpaper in sequence. After further polishing with polishing paste, it is rinsed with alcohol and dried before electrochemical leaching.

[0096] (4) In-situ etching of non-metallic inclusions in the sample, etching environment (electrolyte) temperature -3~-1℃, current density i=0.05 A / cm 2 The leaching time was t = 480 ± 15 s.

[0097] (5) Sample post-treatment: The sample was washed with anhydrous ethanol and dried in a drying oven. The obtained product was observed by SEM. The results are as follows: Figure 4 As shown.

[0098] (6) Results observation: This supplement is combined with routine research and analysis using EBSD metallographic inclusion detection.

[0099] Furthermore, this embodiment can be supplemented by conventional research and analysis using EBSD metallographic inclusion detection to understand the morphological characteristics, size information, and in-situ distribution evolution of inclusions in the sample.

[0100] Comparative Example 1

[0101] This comparative example uses heavy rail steel produced by a certain company. Its smelting chemical composition (mass percentage) consists of the following elements: C 0.67%~0.72%, Si 0.74%~0.80%, Mn 0.70%~0.78%, P≤0.025%, S≤0.025%, Cr 0.0~0.10%, V 0.10%~0.12%, with the remainder being Fe and other unavoidable impurities.

[0102] This comparative example uses a "three-dimensional etching device and etching method for non-metallic inclusions in steel" to etch the target sample:

[0103] (1) Sample preparation: The sample size is cut as follows: 10 mm × 10 mm × 10 mm, and the sample weight is 7.8 g; the shape is made into a regular cube, and the length, width and thickness of the sample are within 1 cm; the surface of the sample to be observed is polished with 400, 800, 1200, 1500 and 2000 grit sandpaper in sequence, polished with polishing paste, and the polished surface is rinsed with alcohol and dried.

[0104] (2) Preparation of etching solution: The etching solution has the following volume percentages: 40% maleic acid ester + 3% tetramethylammonium chloride + balance methanol. The initial pH of the resulting electrolyte is 6.5.

[0105] (3) Electrolysis: The electrolysis device described in "Three-dimensional etching device and etching method for non-metallic inclusions in steel" is used. The temperature of the constant temperature bath is adjusted to make the etching temperature 10℃, and the current density is set to 45 mA / cm². 2 After adjusting the etching parameters, etching begins; the sample is etched in the etching solution, and the substrate on the observation surface gradually dissolves, exposing non-metallic inclusions; etching times are selected as 15 min, 25 min, and 35 min respectively.

[0106] (4) Sample post-treatment: After etching, the sample is cleaned with anhydrous ethanol and dried in a drying oven.

[0107] (5) Results observation: EBSD is used to detect inclusions.

[0108] The results showed that after 15 minutes of etching, significant inclusions detached, and the sample exhibited severe loss of inclusion information. Further etching of newly prepared samples at the minimum etching time of 5 minutes provided by this technique yielded the following results: Figure 5The inclusions still showed significant detachment, and in-situ information was noticeably lacking. Therefore, the "three-dimensional etching device and method for non-metallic inclusions in steel" is not suitable for in-situ detection of non-metallic inclusions in heavy rail steel, especially for larger samples, where the difficulty is even greater.

[0109] Comparative Example 2

[0110] This comparative example uses heavy rail steel produced by a certain company. Its smelting chemical composition (mass percentage) consists of the following elements: C 0.67%~0.72%, Si 0.74%~0.80%, Mn 0.70%~0.78%, P≤0.025%, S≤0.025%, Cr 0.0~0.10%, V 0.10%~0.12%, with the remainder being Fe and other unavoidable impurities.

[0111] This comparative example uses the reagent composition (component content) provided by the present invention to etch the target sample:

[0112] (1) Equipment preparation, the key equipment components are: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0113] (2) Electrolyte preparation: 2.5% lithium chloride, 15% acetylacetone, 40% methanol and 42.5% reagent A. The initial pH of the resulting electrolyte is 7.5.

[0114] (3) Sample preparation: The sample is made into a regular cube with a volume of 5 mm × 18 mm × 30 mm using cutting equipment. The surface of the sample to be observed is polished with 180, 280, 400, 800 and 1200 grit sandpaper in sequence. After further polishing with polishing paste, it is rinsed with alcohol and dried before electrochemical leaching.

[0115] (4) In-situ etching of non-metallic inclusions in the sample, etching environment (electrolyte) temperature 1~2℃, current density i=0.02 A / cm 2 The leaching time is t = 550 s.

[0116] (5) Sample post-treatment: The sample was cleaned with anhydrous ethanol and dried in a drying oven. The obtained product was observed by SEM.

[0117] The results showed that the sample surface was black, making it impossible to observe inclusions.

[0118] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrolyte composition, characterized by, 1.6-2.3 parts by weight of lithium chloride, 10-13.5 parts by weight of acetylacetone, 45-84 parts by weight of methanol, and 2-43 parts by weight of reagent A; The reagent A is an aqueous mixture of ethylenediaminetetraacetic acid and sodium citrate.

2. The electrolyte composition according to claim 1, characterized in that, The mass fraction of sodium citrate in the reagent A is 5%-10%, and the mass fraction of ethylenediaminetetraacetic acid is 5%-10%.

3. The electrolyte composition according to claim 1 or 2, characterized in that, The pH of the electrolyte composition is 7.8-8.

2.

4. The electrolyte composition according to any one of claims 1 to 3, characterized in that, The formula of the electrolyte composition is selected from any one of the following: 1.6% lithium chloride, 10.4% acetylacetone, 45% methanol, and 43% reagent A; Or 2% lithium chloride, 12.5% acetylacetone, 70% methanol, and 15.5% reagent A; Or 2.3% lithium chloride, 10% acetylacetone, 84% methanol, and 3.7% reagent A; Or 1.8% lithium chloride, 13.5% acetylacetone, 70% methanol, and 14.7% reagent A; Or 2% lithium chloride, 12% acetylacetone, 84% methanol, and 2% reagent A.

5. An electrochemical in-situ etching method of non-metallic inclusions for heavy rail steels, characterized in that, The method comprises the following steps: Electrochemical in-situ etching is performed on a heavy rail steel sample using an electrolyte; The electrolyte comprises the electrolyte composition according to claim 1 or 2.

6. The electrochemical in-situ etch process of claim 5, wherein, The heavy rail steel sample comprises the following components by mass fraction: C 0.65%-0.82%, Si 0.10%-0.80%, Mn 0.70%-1.20%, P≤0.025%, S≤0.025%, Cr 0.0-0.50%, V 0.04%-0.12%, and the rest is Fe and other inevitable impurities.

7. The electrochemical in-situ etch method according to claim 5 or 6, c h a r a c t e r i z e d b y, The non-metallic inclusions in the heavy rail steel sample include MnS and composite oxides of Ca, Si, Al, and Mg.

8. The electrochemical in-situ etch method of any one of claims 5-7, wherein, The temperature of the electrochemical in-situ etching is -5~ -1 ℃, the current density is 0.04~0.06 A / cm 2 , and the time is 460~500 S.

9. A method for detecting non-metallic inclusions in heavy rail steel, characterized by, The method comprises the following steps: S1: electrochemical in-situ etching is performed on a heavy rail steel sample according to the electrochemical in-situ etching method of any one of claims 5-8; S2: after the electrochemically in-situ etched sample is cleaned and dried, metallographic inclusion detection is performed.

10. The detection method according to claim 9, characterized in that, The metallographic inclusion detection is performed by EBSD metallographic inclusion detection.

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