Electrochemical in-situ etching process for non-metallic inclusions for bainite steel rail steel and application of electrochemical in-situ etching process

Abstract

The invention provides an electrochemical in-situ etching process for non-metallic inclusions for bainite steel rail steel and application, and the electrochemical in-situ etching process comprises the following steps: immersing a bainite steel rail steel sample into an electrolyte for electrochemical in-situ etching; the electrolyte comprises the following components in percentage by mass: 2.4%-2.5% of lithium chloride, 16%-18% of acetylacetone and the balance of a solvent. By means of the method, three-dimensional in-situ etching of the non-metallic inclusions in the bainite steel rail steel is successfully achieved. In the etching process, a handheld microscope is not needed to observe and judge the exposure effect of the inclusions. According to the technology, the etching process is stable, in-situ information of the non-metallic inclusions in the steel is reserved in the sample subjected to etching, and information such as three-dimensional shapes, size and number distribution and the like of the non-metallic inclusions in different parts of the bainite steel rail steel is analyzed more comprehensively. Related results are more comprehensive, and the development of the bainite steel rail nonmetallic inclusion formation evolution analysis and control process technology is supported accurately.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to an electrochemical in-situ corrosion process for non-metallic inclusions in bainite rail steel and its application. Background Art

[0002] Rails are key components of railway transportation, affecting the high speed, efficiency and safety of railway transportation. With the continuous development of railway transportation, the quality requirements of rails are increasing, and the development of new high-heavy rail products is also rapidly promoted. Among them, non-metallic inclusions in rails are important quality indicators. This is mainly because non-metallic inclusions block the continuity of the matrix structure in the rails, exist as heterogeneous phases, and are prone to deteriorate the mechanical properties of the rails after reaching a certain size. For example, hard Al2O3 will deteriorate the plasticity, toughness and fatigue resistance of the rails, and easily cause the rails to peel off. Large-sized and long-strip MnS inclusions are the main cause of rust, and MnS is a plastic inclusion. It is easy to deform into long-strip MnS inclusions during the rolling process. Such long-strip MnS is the main reason for the increase or even exceeding of the rating results of Class A inclusions, and is also one of the main reasons for the failure of ultrasonic testing. It can be seen that for rails, which are an important part of railway transportation, the control of non-metallic inclusions is very important, so many scholars have carried out a lot of research. Bainitic rail steel has also attracted much attention due to its unique excellent performance, and many scholars have also carried out a lot of research from the perspective of laboratory and industrial experiments.

[0003] As we all know, the study of non-metallic inclusions in steel requires theoretical research from the aspects of thermodynamics and kinetics, and also requires industrial testing in close combination with on-site equipment and process conditions to accurately adjust the actual production process. In the process of precise adjustment of the actual production process, the comprehensive and accurate analysis of the industrial test results is the key to process research. Incomplete or inaccurate test results often lead to inaccurate production process research, and even lead to misjudgment of results, making it difficult to effectively break through related process research. Therefore, the study of non-metallic inclusions in heavy rail steel requires comprehensive and accurate detection of non-metallic inclusions.

[0004] At present, metallographic testing and large sample electrolysis are mostly used for the detection of non-metallic inclusions. In recent years, Aspex scanning statistics and industrial CT scanning have been developed. Among them, two-dimensional detection often makes it difficult to obtain the complete morphology of inclusions, and even the observation information of some inclusions is seriously missing, which is only the "tip of the iceberg" of actual information; secondly, it leads to the lack of detection information of the chemical composition of non-metallic inclusions. Due to the complex formation process of non-metallic inclusions in steel, some inclusions evolve layer by layer at different stages. Two-dimensional detection leads to deviations in the detection results of their chemical composition content, which ultimately leads to misjudgment of the source of inclusions and their formation and evolution behavior mechanism. For the three-dimensional detection of inclusions, the electrolysis method is currently mainly used, including: partial acid etching method, small sample electrolysis method and large sample electrolysis method. The relevant technology obtains more comprehensive inclusion information than two-dimensional detection. However, due to the different chemical compositions of different steel grades, their acid corrosion resistance varies to varying degrees, and the differences in production processes lead to different inclusions. The existing detection methods are less targeted, resulting in a wide range of detection results. Summary of the invention

[0005] The object of the present invention is to provide an electrochemical in-situ corrosion process and application of non-metallic inclusions for bainitic rail steel. The corrosion process in the present invention is stable for the bainitic corrosion process, and the sample after corrosion retains the in-situ information of non-metallic inclusions in the bainitic rail steel, and more comprehensively analyzes the three-dimensional morphology, size and quantity distribution and other information of non-metallic inclusions in different parts of the bainitic rail steel.

[0006] The present invention provides an electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel, comprising the following steps:

[0007] The bainitic rail steel sample is immersed in an electrolyte for electrochemical in-situ corrosion;

[0008] The electrolyte includes the following components by mass fraction:

[0009] 2%~2.5% lithium chloride, 16%~18% acetylacetone and the balance solvent.

[0010] Preferably, the bainitic rail steel comprises the following components in mass fractions:

[0011] C: 0.20%~0.30%, Si: 1.30%~1.70%, Mn: 1.60%~1.90%, P≤0.015%, S≤0.005%, Cr: 0.80~1.00%, V: 0.02%~0.08%, Mo: 0.30%~0.50%, Ni: 0.30%~0.60%, the rest is Fe and other inevitable impurities.

[0012] Preferably, the non-metallic inclusions in the bainitic rail steel include MnS and composite oxides of Ca, Si, Al and Mg.

[0013] Preferably, the bainitic rail steel sample is obtained by pre-treating the bainitic rail steel, wherein the pre-treatment includes cutting, grinding, polishing, rinsing and drying.

[0014] Preferably, the solvent comprises methanol and / or ethanol.

[0015] Preferably, the pH value of the electrolyte is 8-8.5.

[0016] Preferably, the temperature of the electrochemical in-situ etching is -2 to 2°C, and the current density of the electrochemical in-situ etching is 0.5 to 1.0 A / cm 2 The electrochemical in-situ etching time is 500-600s.

[0017] Preferably, the anode of the electrochemical in-situ corrosion is a platinum electrode, the cathode is a corrosion-resistant conductive steel sheet, and the bainitic rail steel sample is connected to the anode.

[0018] Preferably, the detection surface of the bainite rail steel sample is horizontally downward and arranged opposite to the cathode.

[0019] The present invention provides a three-dimensional detection method for non-metallic inclusions in bainitic rail steel, comprising the following steps:

[0020] A) electrochemical in-situ corrosion is performed on bainitic rail steel samples according to the electrochemical in-situ corrosion process described above;

[0021] B) After electrochemical in-situ etching, the bainitic rail steel samples were cleaned and dried for metallographic inclusion detection.

[0022] The present invention provides an electrochemical in-situ etching process for non-metallic inclusions in bainitic rail steel, comprising the following steps: immersing a bainitic rail steel sample in an electrolyte for electrochemical in-situ etching; the electrolyte comprises the following components in mass fractions: 2.4% to 2.5% lithium chloride, 16% to 18% acetylacetone and the remainder of a solvent. The present invention successfully achieves three-dimensional in-situ etching of non-metallic inclusions in bainitic rail steel. The etching process does not require the use of a handheld microscope to observe and determine the effect of inclusion exposure. The etching process of the technology is stable, and the sample after etching retains the in-situ information of non-metallic inclusions in the steel, and more comprehensively analyzes the three-dimensional morphology, size and quantity distribution and other information of non-metallic inclusions in different parts of bainitic rail steel. The three-dimensional morphological features of non-metallic inclusions are more comprehensive than those of two-dimensional detection. After combining with general technical means such as EBSD, the chemical composition of non-metallic inclusions and in-situ distribution information are more comprehensively detected. The relevant results support the analysis of the formation and evolution of non-metallic inclusions in bainitic rail steel and the development of control process technology in a more comprehensive and accurate manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 A schematic diagram of the structure and connection of the electrolytic equipment used in the electrochemical in-situ etching process of the present invention;

[0025] Figure 1 In the figure, 1 is a heat-insulating cover, 2 is a constant temperature pool, 3 is a heat-insulating base, 4 is a platinum electrode, 5 is a corrosion-etched sample, 6 is a corrosion-resistant conductive steel sheet, 7 is an electrolytic cell, 8 is an electrolyte, 9 is an anode, 10 is a cathode, 11 is a DC regulated power supply, and 12 is a household AC power supply;

[0026] Figure 2 This is a picture of the corrosion results of the bainite rail steel in Example 1 of the present invention;

[0027] Figure 3 This is a picture of the corrosion results of the bainite rail steel in Example 2 of the present invention;

[0028] Figure 4 This is a picture of the corrosion results of the bainite rail steel in Example 3 of the present invention;

[0029] Figure 5 The etching current density in comparative example 1 of the present invention is 50 mA / cm 2Picture of corrosion results of bainitic rail steel;

[0030] Figure 6 The etching current density in comparative example 1 of the present invention is 150 mA / cm 2 Picture of corrosion results of bainitic rail steel;

[0031] Figure 7 This is a picture of the corrosion results of bainite rail steel when the corrosion temperature is 5°C in Comparative Example 2 of the present invention;

[0032] Figure 8 This is a picture of the corrosion results of bainite rail steel when the corrosion temperature is 15° C. in Comparative Example 2 of the present invention;

[0033] Fig. 9 This is a picture of the corrosion results of bainite rail steel when the corrosion time is 5°C in Comparative Example 3 of the present invention. DETAILED DESCRIPTION

[0034] The present invention provides an electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel, comprising the following steps:

[0035] The bainitic rail steel sample is immersed in an electrolyte for electrochemical in-situ corrosion;

[0036] The electrolyte includes the following components by mass fraction:

[0037] 2.4%~2.5% lithium chloride, 16%~18% acetylacetone and the balance solvent.

[0038] In the present invention, the smelting chemical composition of the bainitic rail steel includes the following elements in mass fractions:

[0039] C: 0.20%~0.30%, Si: 1.30%~1.70%, Mn: 1.60%~1.90%, P≤0.015%, S≤0.005%, Cr: 0.80~1.00%, V: 0.02%~0.08%, Mo: 0.30%~0.50%, Ni: 0.30%~0.60%, the rest is Fe and other inevitable impurities.

[0040] In the present invention, the non-metallic inclusions in the cast iron rail steel mainly include MnS and composite oxides of Ca, Si, Al and Mg.

[0041] For the study of non-metallic inclusions in steel, in addition to analyzing the composition of non-metallic inclusions, the in-situ information of inclusions is also key to the study of inclusions, that is, it is necessary to maintain the in-situ distribution information of inclusions. For the bainitic rail steel with the above composition and the non-metallic inclusions therein, the present invention specifically provides an electrochemical in-situ etching process, which can not only etch the bainitic rail steel to expose the non-metallic inclusions therein for analyzing its chemical composition, but also ensure that the non-metallic inclusions do not fall off, so as to obtain the shape of the non-metallic inclusions, the original position distribution and other information.

[0042] The present invention preferably pre-treats the bainitic rail steel, specifically, cutting, grinding, polishing, rinsing and drying the bainitic rail steel to obtain a bainitic rail steel sample.

[0043] In the present invention, the cutting can adopt the conventional cutting method in the art, the polishing is preferably performed by using 180, 280, 400, 800 and 1200 grit sandpaper in sequence, and then polishing with polishing paste. In the present invention, the rinsing is preferably performed by using alcohol, and the drying is preferably blow-drying.

[0044] After obtaining the bainite rail steel sample, the present invention connects it with the anode immersed in the electrolyte of the electrolysis equipment, immerses it in the electrolyte, and performs electrochemical in-situ etching.

[0045] In the present invention, the electrolysis equipment is as follows Figure 1 As shown, the bainitic rail steel sample is connected to the anode platinum electrode and horizontally immersed in the electrolyte, the corrosion detection surface of the sample is horizontally facing downward and is horizontally arranged opposite to the cathode corrosion-resistant conductive steel sheet to improve the uneven deposition of electrolytic products on the sample detection surface.

[0046] In the present invention, the electrolyte is a non-aqueous electrolyte, the pH of the electrolyte is 8-8.5, that is, a weakly alkaline electrolyte, and the electrolyte includes the following components in mass fractions:

[0047] 2.4%~2.5% lithium chloride, 16%~18% acetylacetone and the balance solvent.

[0048] In the present invention, lithium chloride is dissolved in acetylacetone to form a complex, which plays a role of a conductive salt in the electrolysis process and promotes charge transfer between electrodes. The mass fraction of the lithium chloride is preferably 2-2.5%, more preferably 2.1-2.4%, such as 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, preferably a range value with any of the above values ​​as the upper or lower limit; the mass fraction of acetylacetone is preferably 16-18%, more preferably 17-18%, such as 16%, 17%, 18%, preferably a range value with any of the above values ​​as the upper or lower limit.

[0049] In the present invention, the solvent is preferably methanol and / or ethanol.

[0050] In the present invention, the temperature of the electrochemical in-situ corrosion is preferably -2~2°C, more preferably -1~1°C, such as -2°C, -1°C, 0°C, 1°C, 2°C, preferably a range value with any of the above values ​​as the upper or lower limit; the current density of the electrochemical in-situ corrosion is preferably 0.5~1.0 A / cm 2 , more preferably 0.6 to 0.8 A / cm 2 , such as 0.5 A / cm 2 , 0.6 A / cm 2 , 0.7 A / cm 2 , 0.8 A / cm 2 , 0.9 A / cm 2 , 1 A / cm 2 , preferably a range value with any of the above values ​​as the upper or lower limit; the time of the electrochemical in-situ corrosion is preferably 500~600s, more preferably 530~570s, such as 500 s, 510 s, 520s, 530 s, 540 s, 550 s, 560 s, 570 s, 580 s, 590 s, 600 s, preferably a range value with any of the above values ​​as the upper or lower limit.

[0051] The present invention also provides a three-dimensional detection method for non-metallic inclusions in bainitic rail steel, comprising the following steps:

[0052] A) electrochemical in-situ corrosion is performed on bainitic rail steel samples according to the electrochemical in-situ corrosion process described above;

[0053] B) After electrochemical in-situ etching, the bainitic rail steel samples were cleaned and dried for metallographic inclusion detection.

[0054] The present invention takes out the bainite rail steel sample after the electrochemical in-situ etching, cleans and dries it, and performs EBSD metallographic inclusion detection.

[0055] In the present invention, the cleaning is preferably performed by anhydrous ethanol cleaning, and the drying is preferably performed by oven drying.

[0056] The present invention provides an electrochemical in-situ etching process for non-metallic inclusions in bainitic rail steel, comprising the following steps: immersing a bainitic rail steel sample in an electrolyte for electrochemical in-situ etching; the electrolyte comprises the following components in mass fractions: 2.4% to 2.5% lithium chloride, 16% to 18% acetylacetone and the remainder of a solvent. The present invention successfully achieves three-dimensional in-situ etching of non-metallic inclusions in bainitic rail steel. The etching process does not require the use of a handheld microscope to observe and determine the effect of inclusion exposure. The etching process of the technology is stable, and the sample after etching retains the in-situ information of non-metallic inclusions in the steel, and more comprehensively analyzes the three-dimensional morphology, size and quantity distribution and other information of non-metallic inclusions in different parts of bainitic rail steel. The three-dimensional morphological features of non-metallic inclusions are more comprehensive than those of two-dimensional detection. After combining with general technical means such as EBSD, the chemical composition of non-metallic inclusions and in-situ distribution information are more comprehensively detected. The relevant results support the analysis of the formation and evolution of non-metallic inclusions in bainitic rail steel and the development of control process technology in a more comprehensive and accurate manner.

[0057] In order to further illustrate the present invention, the electrochemical in-situ corrosion process and application of non-metallic inclusions for bainitic rail steel provided by the present invention are described in detail below in combination with embodiments, but it should not be understood as limiting the protection scope of the present invention.

[0058] Example 1

[0059] This embodiment is a bainitic rail steel produced by a certain enterprise, and its smelting chemical composition (mass percentage) is composed of the following elements: C 0.20%~0.25%, Si 1.30%~1.50%, Mn 1.60%~1.70%, P≤0.010%, S≤0.005%, Cr0.8~0.90%, V0.02%~0.05%, Mo0.30%~0.39%, Ni0.30%~0.40%, and the rest is Fe and other inevitable impurities.

[0060] The key technical parameters involved in the present invention are actually implemented as follows:

[0061] (1) Equipment preparation, the key equipment consists of: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0062] (2) Electrolyte preparation: 2.5% lithium chloride, 16% acetylacetone, 78% methanol solution, and the remainder is unavoidable impurities.

[0063] (3) Sample preparation: Use cutting equipment to make the sample into a regular cube with a volume of 5 mm × 18 mm × 30 mm. 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 blown dry for electrochemical leaching.

[0064] (4) In-situ corrosion of non-metallic inclusions in the sample, corrosion environment (electrolyte) temperature 0°C, current density i = 0.07A / cm 2 , leaching time t=570S.

[0065] (5) Sample post-processing: the samples were cleaned with anhydrous ethanol and dried in a drying oven.

[0066] (6) Result observation, which supplements the conventional research analysis and uses EBSD metallographic inclusion detection.

[0067] EBSD was used to detect the samples that had been in-situ etched, and the morphological characteristics, size information, and in-situ distribution evolution of the inclusions in the samples were mastered. Typical test results are shown in the following photos: Figure 2 shown.

[0068] Example 2

[0069] This embodiment is a bainitic rail steel produced by a certain enterprise, and its smelting chemical composition (mass percentage) is composed of the following elements: C 0.24%~0.27%, Si 1.40%~1.60%, Mn 1.70%~1.80%, P≤0.015%, S≤0.004%, Cr0.88~0.92%, V0.06%~0.08%, Mo0.40%~0.45%, Ni0.57%~0.60%, and the rest is Fe and other inevitable impurities.

[0070] The key technical parameters involved in the present invention are actually implemented as follows:

[0071] (1) Equipment preparation, the key equipment consists of: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0072] (2) Preparation of electrolyte: components: 2.2% lithium chloride, 18% acetylacetone, 77% methanol solution, and the remainder is unavoidable impurities.

[0073] (3) Sample preparation: Use cutting equipment to make the sample into a regular cube with a volume of 5 mm × 18 mm × 30 mm. 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 blown dry for electrochemical leaching.

[0074] (4) In-situ corrosion of non-metallic inclusions in the sample, corrosion environment (electrolyte) temperature 2°C, current density i = 0.07A / cm 2 , leaching time t=560S.

[0075] (5) Sample post-processing: the samples were cleaned with anhydrous ethanol and dried in a drying oven.

[0076] (6) Result observation, which supplements the conventional research analysis and uses EBSD metallographic inclusion detection.

[0077] EBSD was used to detect the samples that had been in-situ etched, and the morphological characteristics, size information, and in-situ distribution evolution of the inclusions in the samples were mastered. Typical test results are shown in the following photos: Figure 3 shown.

[0078] Example 3

[0079] This embodiment is a bainitic rail steel produced by a certain enterprise, and its smelting chemical composition (mass percentage) is composed of the following elements: C 0.26%~0.30%, Si 1.48%~1.70%, Mn 1.83%~1.90%, P≤0.008%, S≤0.005%, Cr0.93~1.00%, V0.05%~0.06%, Mo0.45%~0.50%, Ni0.53%~0.56%, and the rest is Fe and other inevitable impurities.

[0080] The key technical parameters involved in the present invention are actually implemented as follows:

[0081] (1) Equipment preparation, the key equipment consists of: DC regulated power supply, temperature control device, platinum electrode, and electrolytic cell.

[0082] (2) Preparation of electrolyte: components: 2.0% lithium chloride, 17% acetylacetone, 80% methanol solution, and the remainder is unavoidable impurities.

[0083] (3) Sample preparation: Use cutting equipment to make the sample into a regular cube with a volume of 5 mm × 18 mm × 30 mm. 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 blown dry for electrochemical leaching.

[0084] (4) In-situ corrosion of non-metallic inclusions in the sample, corrosion environment (electrolyte) temperature -1 °C, current density i = 0.07 A / cm 2 , leaching time t=540S.

[0085] (5) Sample post-processing: the samples were cleaned with anhydrous ethanol and dried in a drying oven.

[0086] (6) Result observation, which supplements the conventional research analysis and uses EBSD metallographic inclusion detection.

[0087] EBSD was used to detect the samples that had been in-situ etched, and the morphological characteristics, size information, and in-situ distribution evolution of the inclusions in the samples were mastered. Typical test results are shown in the following photos: Figure 4 shown.

[0088] Comparative Example 1

[0089] The bainitic rail steel in Example 1 is used, and the volume percentage of the etching solution components is as follows: 6% lithium chloride + 12% γ-butyrolactone + 10% glycerol + the balance anhydrous ethanol; the etching temperature is 5°C; the etching time is 15 minutes; the etching current density is 50-150 mA / cm 2 Typical etching results are as follows: Figure 5~Figure 6 As shown in the figure, under the corrosion conditions of comparative example 1, the corrosion current density of bainite heavy rail steel is 50mA / cm 2 ( Figure 5 )、150mA / cm 2 ( Figure 6 ) are all characterized by excessive corrosion, a large amount of inclusions falling off, and serious loss of inclusion information.

[0090] Comparative Example 2

[0091] The bainitic rail steel in Example 1 was used, and the volume percentage of the etching solution components was as follows: 4% sodium citrate + 8% sodium chloride + 30% ferrous sulfate + 8% ammonium fluoride + the balance anhydrous ethanol; the etching temperature was 5°C and 15°C respectively; the etching time was 20 minutes; the etching current density was 45 mA / cm 2 Typical etching results are as follows: Figure 7~Figure 8 As shown in the figure, even at 5℃ ( Figure 7 ) conditions, a large amount of inclusions still fall off in bainite heavy rail steel.

[0092] Comparative Example 3

[0093] The bainitic rail steel in Example 1 was used, and the volume percentage of the etching solution components was as follows: 4% sodium citrate + 8% sodium chloride + 30% ferrous sulfate + 8% ammonium fluoride + the balance anhydrous ethanol; the etching temperature was -15°C; the etching time was 5 minutes; the etching current density was 20 mA / cm 2 Typical etching results are shown in the following photos: Fig. 9 As shown in the figure, it can be seen that under the weakest corrosion parameter conditions, inclusions still fall off obviously.

[0094] It can be seen from the results of the above comparative examples and embodiments that different etching solutions and different etching parameters have very different effects on a specific type of steel (bainitic rail steel). This is mainly because the special chemical composition of bainitic heavy rail steel causes it to exhibit special electromagnetic properties. In the electrochemical etching process, inappropriate electrolytes and etching parameters cannot achieve stable corrosion of the steel matrix.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel, comprising the following steps: The bainitic rail steel sample is immersed in an electrolyte for electrochemical in-situ corrosion; The electrolyte includes the following components by mass fraction: 2%~2.5% lithium chloride, 16%~18% acetylacetone and the balance solvent.

2. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The bainitic rail steel comprises the following components in mass fractions: C: 0.20%~0.30%, Si: 1.30%~1.70%, Mn: 1.60%~1.90%, P≤0.015%, S≤0.005%, Cr: 0.80~1.00%, V: 0.02%~0.08%, Mo: 0.30%~0.50%, Ni: 0.30%~0.60%, the rest is Fe and other inevitable impurities.

3. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The non-metallic inclusions in the bainite rail steel include MnS and composite oxides of Ca, Si, Al and Mg.

4. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The bainite rail steel sample is obtained by pre-processing the bainite rail steel, wherein the pre-processing includes cutting, grinding, polishing, washing and drying.

5. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The solvent includes methanol and / or ethanol.

6. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The pH value of the electrolyte is 8-8.

5.

7. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The temperature of the electrochemical in-situ etching is -2 to 2°C, and the current density of the electrochemical in-situ etching is 0.5 to 1.0 A / cm 2 The electrochemical in-situ etching time is 500-600s.

8. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 1, characterized in that: The anode of the electrochemical in-situ corrosion is a platinum electrode, the cathode is a corrosion-resistant conductive steel sheet, and the bainite rail steel sample is connected to the anode.

9. The electrochemical in-situ corrosion process for non-metallic inclusions in bainitic rail steel according to claim 8, characterized in that: The detection surface of the bainite rail steel sample is horizontally downward and is arranged opposite to the cathode.

10. A three-dimensional detection method for non-metallic inclusions in bainitic rail steel, comprising the following steps: A) electrochemical in-situ corrosion is performed on a bainitic rail steel sample according to the electrochemical in-situ corrosion process of claim 1; B) After electrochemical in-situ etching, the bainitic rail steel samples were cleaned and dried for metallographic inclusion detection.

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