Etchant for non-destructive testing of oriented silicon steel solidification structure, preparation method and non-destructive testing method

Abstract

The invention provides an aggressive agent for non-destructive testing of an oriented silicon steel solidification structure, a preparation method and a non-destructive testing method. The preparation method comprises the following steps: S1, adding stannous chloride, anhydrous ferric trichloride, anhydrous copper chloride, anhydrous magnesium chloride and sodium dodecyl benzene sulfonate into deionized water, and stirring for dissolving; and S2, sequentially adding absolute ethyl alcohol and hydrochloric acid into the ionized water, and continuously stirring to obtain the aggressive agent. The aggressive agent is developed for oriented silicon steel for a high-voltage transformer, the aggressive agent is expected to be used for carrying out nondestructive characterization on the solidification structure of an oriented silicon steel casting blank, statistical analysis of the microstructure of the casting blank is facilitated, and a technical basis is provided for optimizing a field continuous casting process and regulating and controlling the solidification structure of the casting blank.

Description

Technical Field

[0001] This invention relates to the field of billet testing and analysis technology, and in particular to an etchant, preparation method and non-destructive testing method for non-destructive testing of solidification structure of grain-oriented silicon steel. Background Technology

[0002] Grain-oriented silicon steel for high-voltage transformers is an important soft magnetic material, widely used in power generation and transmission. With the development of ultra-high-voltage power transmission, high efficiency, high impedance, and low loss have become key performance indicators for large transformers and ballasts. This has led to increasingly stringent requirements for the core loss, magnetic induction intensity, and magnetostriction of grain-oriented silicon steel for high-voltage transformers. As the initial material in the complex and lengthy process of grain-oriented silicon steel rolling and heat treatment, the solidification structure and matrix uniformity of the billet directly affect the subsequent secondary recrystallization, further influencing the magnetic properties of the final product. Therefore, it is necessary to non-destructively reconstruct the solidification structure of the billet. According to metal solidification theory, the solidification structure of the billet is mainly determined by the cooling conditions at the solidification interface. These cooling conditions are related to process parameters such as electromagnetic stirring parameters, superheat, casting speed, and secondary cooling water ratio. Therefore, reconstructing the solidification structure of the grain-oriented silicon steel billet for high-voltage transformers not only allows for understanding the dendrite growth law during solidification but also provides guidance for optimizing continuous casting process parameters.

[0003] Currently, there are two main methods for etching solidified dendritic structures in medium and low carbon steel billets: one is hot acid etching, which requires heating the etching solution to a suitable temperature to etch the billet, such as patent CN117606892A, an etching solution and method for studying the solidification boundary of billets; the other is room temperature etching, where the prepared etching solution is poured onto the test surface of the sample or wiped with degreased cotton, such as patent CN109358066A, a dendritic corrosion reagent for continuously cast steel billets and its preparation and usage method. There are four main methods for preparing etchants: First, patent CN112903402A, a cast dendritic etchant for hot work die steel H13 and its application method, the etchant formula of this invention is: 120-124 mL water, 16.8-17.4 mL nitric acid, 8.5-9.7 mL sulfuric acid, 1.5-2.2 g surfactant (sodium dodecylbenzenesulfonate), 2.1-2.4 g magnesium chloride, 2.2-2.7 g ferric chloride, and 2.2-4.2 g zinc chloride; second, patent CN1308226A, a technology for displaying the solidification structure of continuously cast steel billets, the etchant formula of this invention is: 1-5 g copper chloride, 3-6 g magnesium chloride, 1-4 ml hydrochloric acid, 30-500 ml ethanol, and 15-40 ml water; third, patent CN102023112A, a etchant for displaying the solidification dendritic structure of ultra-low carbon steel and its preparation method. The etching agent consists of the following components: 800-1000 ml distilled water, 1.0-4.0 g picric acid, 1.2-1.5 g stannous chloride, 0.5-4 g copper chloride, 20-40 ml hydrochloric acid, 30-100 ml anhydrous ethanol, and 20-50 ml surfactant; Fourthly, patent CN102174699A, a low-magnification test reagent and preparation method for dendritic corrosion of solidification structure and defects in continuously cast billets, discloses a reagent for displaying dendritic structure of cast billets of AG6K11 steel, 45 steel, Q235B and 16Mn steel. The reagent consists of the following components by mass percentage: 0.28-1.09% copper chloride, 0.17-0.27% magnesium chloride, 0.56-1.60% ferric chloride, 1.28-1.30% hydrochloric acid with a mass concentration of 36-38%, 54.70-55.80% anhydrous ethanol, and the balance being water.

[0004] The above four dendrite etchants generally contain picric acid, ferric chloride, and copper chloride. Etchers containing picric acid have weak corrosive power and a long reaction time, often requiring the addition of ferric chloride to enhance their corrosive ability. However, ferric chloride has strong corrosive power, often severely damaging secondary dendrites, and picric acid is currently difficult to obtain. Etchers containing copper chloride form a precipitate on the etched surface after etching, covering the dendrites. This precipitate needs to be removed with ammonia solution, which not only damages the dendrite morphology but also affects the display effect. Using these four dendrite etchants and their methods to etch the cast iron structure of high-magnetic-induction grain-oriented silicon steel either fails to etch the dendrite structure or produces very poor display results. The dendrite etchants described are mainly suitable for medium and low carbon steel and alloy steel, or cast iron copper alloys; none have been mentioned for low-carbon high-silicon steel.

[0005] Therefore, it is necessary to study an etchant, preparation method, and non-destructive testing method for non-destructive testing of solidification structure of grain-oriented silicon steel to address the shortcomings of existing technologies and solve or mitigate one or more of the above-mentioned problems. Summary of the Invention

[0006] In view of this, the present invention provides an etchant, preparation method and non-destructive testing method for solidification structure of grain-oriented silicon steel. An etchant is developed for grain-oriented silicon steel for high-voltage transformers, with the aim of using the etchant to perform non-destructive characterization of the solidification structure of grain-oriented silicon steel billets, which facilitates statistical analysis of the billet microstructure and provides a technical basis for optimizing the on-site continuous casting process and controlling the solidification structure of the billet.

[0007] On one hand, the present invention provides a method for preparing an etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel, the preparation method comprising the following steps: S1: Add stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride and sodium dodecylbenzenesulfonate to deionized water and stir to dissolve; S2: Add anhydrous ethanol and hydrochloric acid to deionized water in sequence, and continue stirring to obtain the etchant.

[0008] In addition to the aspects and any possible implementations described above, an implementation is further provided, wherein S1 specifically includes: S11: Add stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride and sodium dodecylbenzenesulfonate to deionized water, and use a magnetic stirrer to stir the solid components in the deionized water at a preset speed until the solid components are completely dissolved to obtain the first solution. S12: Add anhydrous ethanol to the first solution and stir to obtain a second solution; add hydrochloric acid to the second solution and stir to obtain the etchant; S13: Obtain the first solution from the deionized water for subsequent addition of anhydrous ethanol.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S11, a magnetic stirrer is used to stir the solid components in the deionized water at a preset speed until the solid components are completely dissolved to obtain a first solution; and in S12, anhydrous ethanol is added after determining the dissolution state from the first solution.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the stirring time on the magnetic stirrer in S11 is 2-4 minutes and the rotation speed is set to 1000-1500 rpm.

[0011] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the stirring time on the magnetic stirrer in S2 is 1~2 min and the rotation speed is set to 1000~1500 rpm.

[0012] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the proportions in S1 and S2 are as follows: per 100 ml of deionized water, 1.2-1.5 g of stannous chloride, 10-15 g of anhydrous ferric chloride, 40-50 ml of anhydrous ethanol, 36 wt%-38 wt% of hydrochloric acid, 15-20 ml of anhydrous copper chloride, 0.3-0.4 g of anhydrous magnesium chloride, and 0.5-1 g of sodium dodecylbenzenesulfonate.

[0013] In accordance with the aspects described above and any possible implementation, an etchant for non-destructive testing of the solidified structure of grain-oriented silicon steel is further provided, wherein the etchant for non-destructive testing of the solidified structure of grain-oriented silicon steel is prepared by the method described above for preparing the etchant for non-destructive testing of the solidified structure of grain-oriented silicon steel.

[0014] In accordance with the aspects described above and any possible implementation, a method for non-destructive testing of solidified structure of grain-oriented silicon steel is further provided, wherein the method achieves non-destructive testing using the etchant described above for non-destructive testing of solidified structure of grain-oriented silicon steel.

[0015] In addition to the aspects and any possible implementations described above, a further implementation is provided, wherein the non-destructive testing method for the solidification structure of the oriented silicon steel specifically includes: Preparation of etchant; (2) Surface pretreatment of the test sample: the test surface of the cast billet sample is ground into a smooth surface with Ra=0.4~0.6μm, and then the smooth surface of the sample is wiped with anhydrous ethanol to remove oil stains; (3) Wiping and erosion: Use tweezers to hold a cotton ball soaked in erosion agent and wipe the test surface of the sample evenly. The erosion time is 15~30s. (4) Sample cleaning: After the etching is completed, put the sample into the water tank and rinse the test surface with running water in one direction. After taking it out, rinse the test surface with anhydrous ethanol in the same direction and dry it with a hair dryer with hot air. (5) Recording of solidified structure: In a well-lit location, use a high-definition camera to take pictures of the solidified structure of the sample.

[0016] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the results of photographing and recording the solidification structure of the sample using a high-definition camera are used to analyze the solidification structure of oriented silicon steel, thereby completing non-destructive testing.

[0017] Compared with the prior art, the present invention can achieve the following technical effects: 1) The etching solution has stable properties, the raw materials are readily available, the etching time is short and no heating is required, making it convenient and easy to implement; 2) The solidification structure has a clear outline, and the columnar and equiaxed dendrites of the grain-oriented silicon steel billet for high-voltage transformers can be directly observed. Furthermore, by measuring the dendrite morphology and dendrite spacing in different regions, the cooling rate and dendrite density of different locations in the grain-oriented silicon steel billet for high-voltage transformers can be obtained. This allows for further optimization of continuous casting process parameters and provides guidance for producing billets dominated by fine and dense columnar crystals.

[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the technical effects described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The macroscopic solidification structure morphology of the etched billet in Example 1 of the present invention; Figure 2 The microstructure of the etched billet after solidification is shown in Example 1 of this invention. Figure 3 The macroscopic solidification structure morphology of the etched billet in Example 2 of the present invention; Figure 4 This is the microstructure of the etched billet after solidification in Example 2 of the present invention. Detailed Implementation

[0021] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0024] This invention provides a non-destructive testing method for the solidification structure of grain-oriented silicon steel. The method aims to accurately expose and record the solidification structure of grain-oriented silicon steel billets through a series of specific steps, providing a reliable basis for subsequent analysis. The technical solution of this invention is described in detail below with reference to specific embodiments to make the objectives, technical solutions, and advantages of this invention clearer.

[0025] In one embodiment, the method provided by this invention is primarily for non-destructive testing of the solidification structure of grain-oriented silicon steel billets. It is applicable to the evaluation of the internal microstructure of materials during steel production, especially in scenarios requiring observation of microscopic features such as dendrite morphology and grain boundary distribution. This method exposes the solidified structure through a combination of chemical etching and surface treatment, while simultaneously using high-definition imaging technology to record the microstructure, laying the foundation for subsequent quality analysis and process optimization. The entire process includes steps such as etchant preparation, sample surface treatment, etching operation, cleaning and drying, and photographic recording. Each step has a specific implementation method to ensure the accuracy and repeatability of the test results.

[0026] Step S1: Prepare the etching agent. Stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride, and sodium dodecylbenzenesulfonate are added to deionized water and stirred until dissolved. Then, anhydrous ethanol and hydrochloric acid are added sequentially, and stirring continues to obtain the etching agent. The purpose of this step is to prepare a chemical reagent that can effectively erode the surface of grain-oriented silicon steel billets and expose the solidified structure. The preparation of the etching agent directly affects the subsequent etching effect; therefore, it is necessary to strictly control the proportions of each component and the stirring conditions. Deionized water is used as the solvent during preparation to avoid interference from impurities in the chemical reaction. The selection of each chemical reagent is based on its specific etching effect on the grain-oriented silicon steel surface. For example, stannous chloride and anhydrous ferric chloride can react mildly with the steel surface, gradually peeling off the surface layer and exposing the internal structure; anhydrous copper chloride and anhydrous magnesium chloride play a role in assisting etching and stabilizing the reaction; sodium dodecylbenzenesulfonate, as a surfactant, can improve the wettability of the etching agent, allowing it to adhere more evenly to the sample surface.

[0027] In one possible implementation, step S1 can be further broken down into several sub-steps to ensure the uniformity and stability of the etchant. Step S11: Stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride, and sodium dodecylbenzenesulfonate are added sequentially to deionized water. During operation, the deionized water can be poured into a corrosion-resistant glass container first, and then the above chemical reagents are added slowly in a specific order to avoid precipitation caused by excessively high local concentrations due to rapid addition. Step S12: Use a magnetic stirrer to stir at an appropriate speed until all solid components are completely dissolved, forming a homogeneous first solution. The stirring time is generally controlled between 20 and 30 minutes, and the speed can be adjusted according to the container size and solution volume, usually between 300 and 500 rpm, to avoid excessive bubbles or uneven stirring. Step S13: Anhydrous ethanol is slowly added to the first solution, and stirring continues for 10 to 15 minutes to obtain the second solution. The addition of anhydrous ethanol can improve the volatility and permeability of the etchant, making it easier to distribute evenly during subsequent wiping. Step S14: Slowly add hydrochloric acid to the second solution and continue stirring for 5 to 10 minutes to obtain the etching agent. The addition of hydrochloric acid requires extreme caution; it is recommended to operate in a fume hood to avoid harm to operators from acidic gases. Through the above steps, the resulting etching agent is uniformly transparent and possesses good chemical stability and etching ability.

[0028] For example, in actual production scenarios, the proportions of each component can be adjusted according to the specific composition of the grain-oriented silicon steel billet and the testing requirements when preparing the etching agent. For grain-oriented silicon steel with a high carbon content, the amount of anhydrous ferric chloride can be appropriately increased to enhance the etching depth; while for samples with a thicker surface oxide layer, the proportion of sodium dodecylbenzenesulfonate can be increased to improve the wetting effect of the etching agent and ensure uniform etching. In the testing laboratory of a steel company, when preparing the etching agent, technicians first placed 500 ml of deionized water in a glass beaker, then added 5 g of stannous chloride, 10 g of anhydrous ferric chloride, 3 g of anhydrous copper chloride, 2 g of anhydrous magnesium chloride, and 1 g of sodium dodecylbenzenesulfonate in sequence. The mixture was stirred at 400 rpm for 25 minutes using a magnetic stirrer until the solids were completely dissolved. Then, 50 ml of anhydrous ethanol was added and stirred for 15 minutes. Finally, 10 ml of hydrochloric acid was added and stirred for 10 minutes to obtain the final etching agent. This preparation method has shown good erosion effect in multiple experiments, and can clearly expose the dendritic structure of the solidified tissue, providing a reliable sample surface for subsequent analysis.

[0029] In another embodiment, the effect of ambient temperature on the dissolution effect can be considered when preparing the etching agent. In low-temperature environments, such as when the laboratory temperature is below 10 degrees Celsius in winter, the dissolution rate of solid reagents may be slow. In this case, the stirring time can be appropriately extended to 40 minutes, or the deionized water can be preheated to 20 to 25 degrees Celsius before adding the reagents to accelerate the dissolution process. In high-temperature environments, such as when the summer temperature exceeds 30 degrees Celsius, attention should be paid to the volatility of anhydrous ethanol and hydrochloric acid. It is recommended to reduce the stirring speed to 200 rpm when adding these two components and ensure the container is sealed to avoid evaporation loss. In this way, a stable etching agent can be obtained under different environmental conditions, ensuring the smooth progress of subsequent etching steps.

[0030] Step S2 involves grinding the test surface of the grain-oriented silicon steel billet sample to a smooth finish and wiping it with anhydrous ethanol to remove oil stains. The purpose of this step is to provide a smooth and uncontaminated test surface for subsequent etching operations through machining and cleaning. During the production process, the surface of the grain-oriented silicon steel billet may contain oxide scale, oil stains, or other impurities. Without pretreatment, direct etching may result in uneven etching, affecting the exposure of the solidified structure. Therefore, grinding and cleaning are crucial steps to ensure test quality. The goal of grinding is to achieve a smooth surface with a certain surface roughness standard, allowing the etchant to act evenly on the surface.

[0031] In one possible implementation, step S2 can be further refined into multiple sub-steps to ensure the quality of the test surface. Step S21 involves grinding the test surface of the grain-oriented silicon steel billet sample until the surface roughness value reaches a specified range. The grinding process can be performed using a grinding wheel or sandpaper. It is recommended to start with coarse sandpaper and gradually transition to fine sandpaper. For example, first use 80-grit sandpaper for coarse grinding to remove large particles and oxide layers, then use 400-grit sandpaper for medium grinding, and finally use 1200-grit sandpaper for fine grinding, until the surface roughness value reaches the range of 0.8 to 1.6 micrometers. During grinding, the sample must be kept fixed to avoid surface unevenness caused by shaking. It is also recommended to add a small amount of coolant during the grinding process to prevent localized surface deterioration due to frictional heat. Step S22 involves wiping the smooth surface with anhydrous ethanol to remove oil stains, obtaining the pre-treated test surface of the sample. When wiping, a lint-free cloth soaked in anhydrous ethanol can be used to repeatedly wipe in one direction until there are no obvious oil stains on the surface. Step S23: Obtain a clean surface from the pretreated sample testing surface for subsequent etching operations. Through the above steps, the sample testing surface achieves a smooth and clean state, providing a good foundation for the uniform action of the etchant.

[0032] For example, in the quality inspection department of a steel production company, technicians typically use a precision grinding machine to grind samples of grain-oriented silicon steel billets. First, the sample is fixed on the grinding machine's worktable, and an 80-grit wheel is used for rough grinding for 5 minutes to remove the surface oxide layer and larger particles. Then, a 400-grit wheel is used for medium grinding for 3 minutes, and finally, a 1200-grit wheel is used for fine grinding for 2 minutes until the surface has a uniform gloss and the roughness value is controlled at approximately 1.2 micrometers. After grinding, a lint-free cloth soaked in anhydrous ethanol is used to wipe the sample surface three times from left to right in a single direction to ensure no oil or dust residue remains. This treatment method has proven in multiple tests to effectively improve the uniformity of subsequent etching, making the solidified structure more clearly visible, and providing a high-quality sample surface for subsequent testing.

[0033] In another embodiment, the grinding parameters can be adjusted appropriately for grain-oriented silicon steel billet samples of different specifications. For thicker billet samples, such as those exceeding 50 mm in thickness, due to the potential presence of deep rolling marks or oxide layers on the surface, the rough grinding time can be increased to 8 minutes, and coarser 60-grit sandpaper should be used in the first two grinding steps to remove surface defects more quickly. For thinner samples, such as those less than 20 mm thick, the grinding force should be reduced to avoid excessive grinding that could deform the sample. It is recommended to use 400-grit or higher sandpaper throughout the process and keep the total grinding time below 5 minutes. Furthermore, when wiping away oil stains, if the sample surface is heavily soiled, a small amount of acetone can be used for initial cleaning, followed by a second wipe with anhydrous ethanol to ensure thorough cleaning. This flexible adjustment method can adapt to the needs of different sample characteristics and ensure the quality of the test surface.

[0034] In another embodiment, grinding can be combined with automated equipment to improve efficiency and consistency. In the testing laboratories of some large steel companies, technicians use automated grinding and polishing machines to surface-treat grain-oriented silicon steel billet samples. These machines have built-in multiple sandpaper sizes and can be programmed to sequentially complete rough grinding, medium grinding, and fine grinding steps. For example, rough grinding can be set to use 80-grit sandpaper for 5 minutes; medium grinding to use 400-grit sandpaper for 3 minutes; and fine grinding to use 1200-grit sandpaper for 2 minutes. During operation, the sample is fixed on a rotating platform, and the sandpaper disc contacts the sample surface at a uniform speed to ensure even grinding. After grinding, technicians still need to manually wipe the surface with anhydrous ethanol to remove any remaining fine dust. This method is particularly suitable for batch testing scenarios, significantly improving processing efficiency while ensuring the consistency of the quality of each sample's test surface, laying a solid foundation for subsequent etching and testing.

[0035] Step S3: Using tweezers, hold a piece of degreased cotton soaked in the etchant and evenly wipe the sample testing surface to etch it. The purpose of this step is to chemically treat the sample testing surface with the etchant, thereby exposing the solidified structure of the grain-oriented silicon steel billet. The etching operation is the core of the entire testing process, directly determining the clarity and integrity of the exposed solidified structure. During the operation, it is necessary to control the amount of etchant, the uniformity of wiping, and the duration of etching to avoid over-etching which could damage the microstructure, or under-etching which would result in indistinct microstructure exposure. Using tweezers to hold the degreased cotton for wiping avoids direct hand contact with the etchant, ensuring operational safety, and also allows for more precise control of the wiping force and area.

[0036] In one possible implementation, step S3 can be further refined into multiple sub-steps to ensure the etching effect. Step S31: Use tweezers to hold a piece of absorbent cotton and soak it in the etching agent. It is recommended to use medical-grade absorbent cotton to ensure it is free of impurities and has good absorbency. When soaking in the etching agent, the cotton should be immersed in the agent for 2 to 3 seconds to ensure it absorbs the liquid fully without dripping. Step S32: Wipe the sample surface evenly with the absorbent cotton, maintaining a certain etching time. Wiping should be done in one direction, such as from left to right or from top to bottom, at a uniform speed to avoid repeatedly wiping the same area, which could lead to uneven etching. The etching time is generally controlled between 30 and 60 seconds, and the specific time can be adjusted according to the sample material and the concentration of the etching agent. Step S33: Obtain the etched surface from the sample surface for subsequent cleaning operations. Step S34: Determine the initial exposure of the solidified structure on the etched surface. The etching effect can usually be judged by visually observing whether dendrite outlines or grain boundary traces appear on the surface. Through the above steps, the surface layer of the sample test surface is slightly peeled off under the action of the etchant, and the solidified structure is initially revealed.

[0037] For example, in the testing laboratory of a steel company, technicians typically use long-handled stainless steel tweezers to hold a piece of medical absorbent cotton about 5 cm square. They immerse the cotton in a pre-prepared etching agent for about 3 seconds, allowing it to fully absorb the liquid. Then, they gently squeeze out excess liquid to prevent dripping. Holding the tweezers, the technicians begin wiping the sample surface from the upper left corner to the lower right corner horizontally at a uniform speed, a process that lasts about 40 seconds, ensuring even coverage of each area. After wiping, the sample surface appears slightly grayish-white, with fine dendrite outlines visible in some areas, indicating the initial exposure of the solidified structure. This method has demonstrated good stability in multiple tests, effectively avoiding uneven or excessive etching, and providing a good sample surface for subsequent cleaning and photographic recording.

[0038] In another embodiment, the etching time and method can be adjusted appropriately for different types of grain-oriented silicon steel billet samples. For samples with smaller grain sizes, due to their finer solidification structure, the etching time can be shortened to 30 seconds to avoid over-etching and blurring of the microstructure boundaries; while for samples with larger grain sizes, the etching time can be extended to 60 seconds to ensure that the microstructure is fully exposed. Furthermore, if the sample inspection area is large, such as exceeding 100 square centimeters, it can be wiped in sections, completing the etching of one section before moving on to the next, with each section's wiping time controlled at 20 to 30 seconds to ensure consistent overall etching results. In one test, technicians performed sectioned etching on a sample with an area of ​​approximately 150 square centimeters, dividing the inspection surface into three sections, wiping each section for 25 seconds, for a total time of approximately 75 seconds. Ultimately, the etching depth was consistent across all sections of the sample surface, and the dendritic structure was clearly visible. This sectioned operation method is particularly suitable for large-area samples and can effectively improve the uniformity of etching.

[0039] In another embodiment, the etching operation can be combined with auxiliary tools to further improve operational accuracy. In some high-precision testing scenarios, technicians use a small adjustable stand to fix tweezers on the stand. By adjusting the height and angle of the stand, they ensure uniform pressure when the absorbent cotton comes into contact with the sample surface. During operation, the absorbent cotton is first soaked in the etchant, then the sample is placed on the worktable below the stand. The stand is adjusted so that the absorbent cotton just touches the sample surface, and then the stand is moved at a uniform speed along a preset path to complete the wiping process. This method can effectively reduce the problem of uneven force caused by manual operation, especially when long-term etching or processing of multiple samples is required, and can significantly improve operational consistency. In a laboratory experiment, the dendritic structure of the sample surface etched using this stand-assisted method was more uniformly revealed, and the grain boundary lines were clearer than those obtained manually, providing higher quality image data for subsequent microstructure analysis.

[0040] It is important to note that the environmental conditions for etching operations also require special attention. It is recommended to perform the operation in a well-ventilated laboratory or fume hood to avoid harm to operators from acidic gases produced by the evaporation of the etching agent. Simultaneously, acid- and alkali-resistant gloves and safety goggles must be worn during operation to ensure safety. Furthermore, if the etching agent shows significant evaporation during the wiping process or the absorbent cotton is insufficient, a small amount of etching agent can be added again midway, but care must be taken to avoid liquid dripping onto the sample surface, which could lead to excessively deep localized etching. In one test, due to the high ambient temperature, the etchant evaporated rapidly. When the absorbent cotton dried out during the wiping process, a small amount of etching agent was promptly added to continue wiping, and the sample surface ultimately maintained good etching uniformity. This flexible approach allows for achieving ideal etching results under various conditions.

[0041] In one embodiment, the etching time control in step S3 can also be aided by observing the color change of the sample surface to determine the etching progress. Typically, the sample surface is silvery-white in the early stages of etching, gradually turning grayish-white as etching progresses, and exhibiting a light gray color with fine textures when the solidified structure is exposed. At this point, wiping can be stopped to avoid excessive etching and damage to the microstructure. During testing at a steel company, technicians found that when the sample surface color changed from silvery-white to grayish-white and fine textures appeared, the etching time had typically reached approximately 40 seconds. At this point, wiping was stopped, and the dendritic structure and grain boundary distribution on the sample surface were clearly visible. This method of using color change to aid judgment is particularly suitable for novice operators, effectively reducing the risk of operational errors.

[0042] For example, in practical applications, the details of the etching operation can be further optimized according to the specific condition of the sample. For samples with minor scratches on the surface, the scratched area can be lightly sanded with fine sandpaper before etching to make its surface roughness consistent with other areas, and then wiped to avoid excessive etching at the scratches. For samples with localized oxide layers on the surface, the oxide layer area can be wiped with slightly more force during etching, or the etching time in that area can be extended to 50 seconds to ensure that the oxide layer is effectively removed and the solidified structure is exposed. In one test, technicians used 1500-grit sandpaper to lightly sand the scratched area of ​​a sample with minor scratches for about 1 minute, and then carried out the etching operation. The scratched area was wiped with slightly more force for 45 seconds, while other areas were wiped normally for 40 seconds. The final result was a consistent etching effect on the entire sample surface, and the solidified structure was clearly exposed. This targeted treatment method can effectively address localized defects on the sample surface and ensure the reliability of the test results.

[0043] In another possible implementation, the etching operation in step S3 can be combined with multiple wiping steps to further improve the exposure of the solidified structure. Step S321: After applying the etchant to a piece of absorbent cotton with tweezers, wipe the sample surface from left to right at a uniform speed for 20 seconds. Step S322: After wiping, observe the color change of the sample surface. If no obvious texture appears, replace the cotton with a new piece of absorbent cotton, apply the etchant again, and wipe from top to bottom for 15 seconds. Step S323: Repeat the above process until a light gray color with fine texture appears on the sample surface, with a total etching time not exceeding 60 seconds. This method of wiping in stages gradually exposes the solidified structure, avoiding excessively deep etching caused by excessively long wiping times. In a laboratory experiment, technicians wiped a sample of grain-oriented silicon steel billet twice. After the first wipe, which lasted 20 seconds, the surface color changed slightly, but the texture was not obvious. After the second wipe, which lasted 15 seconds, the surface turned light gray, and the dendrite outlines were clearly visible. The total time taken was 35 seconds, and the results were ideal. This method is particularly suitable for testing scenarios that require high etching depth and can effectively improve the quality of microstructure exposure.

[0044] It should be noted that after the etching process, the sample surface is usually somewhat moist and may contain a small amount of residual etching agent. At this point, it is not advisable to take photos directly; subsequent cleaning and drying are necessary to avoid interference from liquid residue on the imaging results. Furthermore, the etched sample surface is quite sensitive and subsequent steps should be completed as soon as possible to avoid prolonged exposure to air, which could lead to surface oxidation or contamination and affect the accuracy of the test results. In one test, due to a temporary interruption of the operation after etching, the sample surface was exposed to air for approximately 30 minutes, resulting in slight oxidation marks in some areas, affecting the clarity of subsequent photographs. Therefore, it is recommended to clean and dry the sample surface immediately after etching to ensure optimal condition.

[0045] In one embodiment, the evaluation of the etching effect in step S3 can also be preliminarily judged using auxiliary tools. For example, after etching is completed, a 10x magnifying glass can be used to observe the sample surface to check whether the dendritic structure or grain boundary lines are clearly visible. If some areas are found to be not clearly exposed, these areas can be locally wiped for 10 to 15 seconds to avoid excessive overall etching. In the testing process of a steel company, after etching was completed, technicians used a magnifying glass to find that the dendritic structure at the edge of the sample was not clearly exposed. Subsequently, they wiped this area for 12 seconds, and finally the overall microstructure of the sample surface became clear, achieving the expected effect. This method of auxiliary observation and local adjustment can effectively improve the accuracy of the etching operation and ensure the full exposure of the solidified structure.

[0046] For example, in some demanding testing scenarios, etching can be combined with pre-marking of the sample surface to improve the targeting of the operation. Before etching, technicians can use an acid- and alkali-resistant marker to mark key observation areas on the sample surface, such as specific areas near the center or edge of the billet. Then, during wiping, slightly more pressure is applied to the marked areas or the etching time is extended to 50 seconds to ensure that the solidified structure in these critical areas is fully exposed. In one test, technicians pre-marked a grain-oriented silicon steel billet sample, focusing on the dendrite distribution in the central region of the billet. During wiping, the etching time for this area was extended to 48 seconds, while other areas remained at 40 seconds. Ultimately, the dendrite structure and grain boundary distribution in the marked areas were clearly visible, providing targeted data support for subsequent analysis. This method is particularly suitable for testing tasks requiring focused analysis of the microstructure of specific areas, effectively improving the targeting and efficiency of the testing.

[0047] In another embodiment, the etching operation in step S3 can be customized according to the characteristics of the sample material. Different compositions and heat treatment processes of grain-oriented silicon steel billets may lead to variations in surface hardness and chemical reactivity. For example, for samples that have undergone high-temperature annealing, the surface may be relatively dense, resulting in a slower action rate of the etchant. In this case, the etching time can be appropriately extended to 60 seconds, or slight force can be applied during wiping to ensure sufficient etching depth. For unannealed samples, the surface is relatively porous, leading to a faster etching rate. It is recommended to shorten the etching time to 30 seconds and reduce the wiping force to avoid excessive damage to the microstructure. In a laboratory experiment, technicians etched two samples with different treatment processes: one annealed sample with an etching time of 55 seconds and slightly stronger wiping force; the other unannealed sample with an etching time of 32 seconds and lighter wiping force. Both samples ultimately exhibited a clear solidified microstructure, demonstrating the effectiveness of this customized adjustment method.

[0048] It is important to note that the success of the etching operation depends not only on the wiping time and pressure, but also on the concentration of the etchant and the initial state of the sample surface. Therefore, in practice, it is recommended to conduct a pre-etching test on a small piece of waste material before the formal testing to determine the optimal wiping time and pressure parameters, which can then be applied to the formal sample to avoid testing failure due to inappropriate parameters. In one test, technicians conducted a pre-test on a piece of waste material before the formal operation, trying three etching times: 30 seconds, 40 seconds, and 50 seconds. They ultimately found that 40 seconds provided the best exposure of the sample surface structure. This parameter was then applied to the formal sample, successfully obtaining a clear image of the solidified structure. This pre-testing method effectively reduces operational risks and ensures the smooth progress of the testing process.

[0049] In one possible implementation, the uniformity of wiping in step S3 can be further improved by training operators or establishing standard operating procedures. In the testing departments of some steel companies, technicians undergo specialized training before performing etching operations, learning how to control the wiping direction, pressure, and time. They practice repeatedly using simulated samples until the operation meets the standard requirements. Furthermore, the companies have established detailed operating specifications, such as requiring unidirectional wiping, a time limit of 35 to 45 seconds, and gentle squeezing to remove excess liquid after the absorbent cotton has absorbed it, ensuring that every operator follows a unified standard. In a batch testing operation, technicians strictly followed the operating specifications, and all 20 treated samples showed a consistent etching effect, with clearly exposed solidified structures, providing reliable data support for subsequent analysis. This standardized operating method is particularly suitable for large-scale testing tasks, effectively reducing the impact of human error.

[0050] For example, in practical applications, the details of the etching process can be optimized according to the specific conditions of the laboratory. In some small laboratories with limited resources, there may not be enough ventilation equipment or corrosion-resistant containers. In such cases, the etching agent can be prepared in batches of small quantities, only enough for one use at a time, to reduce the risk of evaporation and storage. Simultaneously, when wiping, a small test tube is used to drop the etching agent onto the absorbent cotton to avoid large-area soaking and liquid waste. In a test conducted in a small laboratory, technicians prepared only 50 ml of etching agent each time, adding the liquid drop by drop to the absorbent cotton using a dropper, followed by wiping. This process took approximately 40 seconds, and the final exposure of the sample surface tissue was excellent, demonstrating the feasibility of this method under resource-constrained conditions. Through this flexible adjustment, ideal etching results can be achieved under various conditions.

[0051] In another embodiment, the etching operation in step S3 can be combined with real-time monitoring of the sample surface to further improve accuracy. In some high-precision testing scenarios, technicians use a portable microscope to observe the sample surface in real time during the wiping process, pausing every 10 seconds to check the exposure of the tissue. If insufficient exposure is found in some areas, targeted additional wiping is performed on those areas until the overall effect meets the requirements. In one test, technicians performed real-time monitoring wiping on a sample. After the first 10-second wipe, insufficient exposure was found in the central area. An additional 10-second wipe was then performed on that area, and the overall tissue structure of the sample surface was finally clearly visible, with a total time of approximately 35 seconds. This real-time monitoring method can effectively improve the accuracy of the etching operation, ensure the full exposure of the solidified tissue, and provide a high-quality sample surface for subsequent testing.

[0052] It is important to note that the etching process, as the core step in the entire testing process, directly impacts the accuracy of subsequent photographic recording and microstructure analysis. Therefore, in practice, it is recommended to comprehensively consider factors such as sample characteristics, etchant concentration, wiping time, and intensity, flexibly adjusting operating parameters. Furthermore, the process should be optimized through pre-testing and real-time monitoring to ensure optimal exposure of the solidified structure. In the quality inspection of a steel company, technicians, through multiple experiments and parameter adjustments, ultimately determined an etching procedure suitable for specific orientation silicon steel billets. This included parameters such as an etching time of 40 seconds, wiping direction from left to right, and uniform intensity. This successfully achieved clear exposure of the solidified structure, providing crucial reference data for subsequent process optimization.

[0053] In one embodiment, the protection of the sample surface is also important for the subsequent processing in step S3. Because the etched sample surface exposes the internal structure, it is susceptible to oxidation or contamination from moisture or impurities in the air. Therefore, it is recommended to clean and dry the sample as soon as possible after etching to avoid prolonged exposure. In some testing scenarios, if immediate cleaning is not possible due to equipment or time constraints, the etched sample can be temporarily placed in a desiccator with desiccant to absorb moisture from the air and reduce the risk of oxidation. In one test, due to a temporary malfunction of the cleaning equipment, technicians placed the etched sample in a desiccator for approximately 20 minutes before cleaning and drying. Ultimately, no obvious oxidation marks appeared on the sample surface, and the tissue exposure remained excellent. This temporary protection method effectively addresses unexpected situations and ensures that the sample quality is not affected.

[0054] For example, in practical applications, the details of the etching operation can be further optimized according to the detection target. If the detection target is to observe the macroscopic morphology of the solidified structure, the etching time can be appropriately shortened to 30 seconds, and the wiping force can be reduced to avoid excessive etching that would obscure the macroscopic structure. Conversely, if the target is to observe the microscopic grain boundary distribution, the etching time can be extended to 50 seconds, and the wiping force can be increased to ensure that the microscopic structure is fully exposed. In one test, technicians set etching times of 30 seconds and 50 seconds for two samples respectively, based on different detection targets. Ultimately, the two samples exhibited clear macroscopic dendrite morphology and microscopic grain boundary distribution, meeting different analytical needs. Through this targeted adjustment method, different detection targets can be flexibly adapted to, improving the applicability of the detection results.

[0055] In another possible implementation, the wiping operation in step S3 can be further optimized by recording and analyzing the parameters of each operation. In the testing departments of some steel companies, technicians record information such as wiping time, force, direction, and the exposure effect on the sample surface after each etching operation. This data is then statistically analyzed to determine the optimal range of operating parameters. For example, analysis of 50 etching operations revealed that a wiping time of 38 to 42 seconds, a left-to-right direction, and a moderate force resulted in the best exposure of the sample surface structure. This parameter range was then used as a standard operating guideline in subsequent tests, ultimately significantly improving operational consistency and testing quality. This data-driven optimization method is particularly suitable for long-term testing tasks and can effectively improve overall efficiency.

[0056] It should be noted that successful implementation of the etching operation requires operators to possess certain experience and skills, especially in controlling the wiping force and time, which needs to be mastered through repeated practice. Therefore, it is recommended that experienced operators be assigned to key steps in actual operations, or that training and simulation exercises be used to improve the skill level of novice operators. In the testing process of a certain laboratory, technicians organized multiple simulated operation training sessions, enabling novice operators to gradually master the techniques for controlling the wiping force during practice before formal testing. Ultimately, in the formal testing, they achieved etching results similar to those of experienced operators, ensuring the reliability of the test results.

[0057] In one embodiment, the etching operation in step S3 can be comprehensively adjusted in conjunction with the pretreatment state of the sample surface. If there are still minor scratches or uneven areas on the sample surface after grinding, these areas can be lightly wiped during etching, or localized polishing can be performed with ultra-fine sandpaper before wiping to ensure a consistent surface condition before etching. In one test, technicians found a minor scratch on the sample surface. They then lightly polished the scratched area with 2000-grit sandpaper for 1 minute before etching. Ultimately, the overall etching effect on the sample surface was consistent, and the solidified structure was clearly revealed. This comprehensive adjustment method can effectively address local defects on the sample surface and ensure the smooth progress of the testing process.

[0058] For example, in practical applications, the details of the etching operation can be optimized according to the specific equipment conditions of the laboratory. In some laboratories equipped with precision operating tables, technicians can fix the sample on the table and adjust the angle of the table to ensure that the sample surface is horizontal when in contact with the absorbent cotton, and then perform the wiping operation to ensure uniform pressure. In one test, the technician used a precision operating table to fix the sample, adjusted the angle to make the surface horizontal, and then performed the wiping operation, which took about 40 seconds. The final result showed good exposure of the sample surface structure, with the dendritic structure and grain boundary distribution clearly visible. This method is particularly suitable for high-precision testing scenarios and can effectively improve the stability and consistency of the operation.

[0059] In another embodiment, the erosion effect of step S3 can also be evaluated by comparing it with historical data. In the testing departments of some steel companies, technicians compare the exposure effect of the sample surface with high-quality samples from previous tests after each erosion operation. If the current sample exposure effect is found to be unsatisfactory, possible causes are analyzed, such as insufficient erosion time or uneven wiping, followed by adjustments and supplementary operations. In one test, technicians found that the dendritic structure on the sample surface was not clearly exposed. After comparing it with historical high-quality samples, they determined that the erosion time was insufficient. The sample was then wiped for an additional 15 seconds, ultimately achieving an exposure effect similar to historical samples. This comparative evaluation method can effectively improve the testing quality and ensure that each operation achieves the expected goals.

[0060] Step S4: After etching, rinse the test surface of the sample with running water, then rinse with anhydrous ethanol and dry with hot air. The purpose of this step is to remove residual etchant and reaction products from the test surface of the sample, preventing these residues from interfering with subsequent photographic recording. Simultaneously, drying prevents surface oxidation or residual moisture from affecting the imaging effect. Cleaning and drying are crucial steps to ensure the complete preservation of the solidified structure exposure effect. During operation, attention must be paid to the thoroughness of cleaning and the uniformity of drying to ensure the sample surface is in optimal condition.

[0061] In one possible implementation, step S4 can be further broken down into several sub-steps to ensure effective cleaning and drying. Step S41: Place the sample in a water tank and rinse the test surface with running water in one direction. During operation, it is recommended to place the sample in the water tank, turn on the tap to allow water to continuously rinse the test surface at a moderate flow rate, maintaining a consistent rinsing direction, for example, from top to bottom of the sample. The rinsing time is generally controlled to 1 to 2 minutes to ensure that any residual etchant on the surface is thoroughly rinsed away. Step S42: After removing the sample from the water tank, rinse the test surface with anhydrous ethanol in the same direction. Rinsing with anhydrous ethanol can further remove any remaining moisture and trace impurities. During rinsing, anhydrous ethanol can be poured into a small spray bottle, sprayed evenly onto the test surface, and then gently wiped with a lint-free cloth for 30 to 60 seconds. Step S43: Use a hairdryer on a hot setting to dry the test surface, obtaining the dried sample. When drying, the hair dryer should be set to the hot air setting, with the nozzle approximately 10 to 15 centimeters away from the sample surface. Move the dryer evenly along the test surface to ensure no moisture remains. The drying time is generally 1 to 2 minutes. Step S44: Obtain the clean, solidified tissue from the dried sample for subsequent photographic recording. Through the above steps, the sample test surface is thoroughly cleaned and dried, and the solidified tissue structure remains clear, providing excellent conditions for subsequent imaging.

[0062] For example, in the testing laboratory of a steel company, after completing the etching process, technicians placed the sample in a water tank and turned on the tap to allow clean water to flow from the top to the bottom of the sample at a moderate flow rate, rinsing continuously for 1.5 minutes to ensure that any residual etching agent on the surface was completely removed. Then, the sample was removed from the tank, and anhydrous ethanol was evenly sprayed onto the test surface using a small spray bottle. A lint-free cloth was then gently wiped from top to bottom for about 40 seconds to remove residual moisture and fine impurities. Finally, a hairdryer was set to the hot air setting, with the nozzle about 12 cm away from the sample surface, and moved at a uniform speed from left to right along the test surface for about 1.5 minutes to dry the sample. The final sample surface was dry, and the solidified structure was clearly visible. This method demonstrated good cleaning and drying effects in multiple tests, ensuring the image quality for subsequent photographic recordings.

[0063] In another embodiment, the cleaning and drying parameters can be adjusted appropriately for grain-oriented silicon steel billet samples of different specifications. For samples with larger areas, such as those with a test surface area exceeding 100 square centimeters, the rinsing time with clean water can be extended to 2.5 minutes, and the rinsing direction can be varied, for example, rinsing from top to bottom for 1 minute, then from left to right for 1.5 minutes, to ensure that residues on large surfaces are thoroughly removed. For samples with smaller areas, such as those with a test surface area less than 50 square centimeters, the rinsing time with clean water can be shortened to 1 minute to avoid excessive rinsing that could damage local surface tissues. When rinsing with anhydrous ethanol, if a small amount of stubborn residue remains on the sample surface, the wiping time can be increased to 1.5 minutes, and the wiping force can be appropriately increased. When drying, if the ambient humidity is high, the distance between the blower and the sample surface can be adjusted to 8 centimeters, and the drying time extended to 2.5 minutes to ensure complete evaporation of moisture. In one test, technicians cleaned a sample with an area of ​​about 120 square centimeters. First, they rinsed it with clean water from top to bottom for 1 minute, then from left to right for 1.5 minutes. After that, they wiped it with anhydrous ethanol for 1 minute, and finally dried it with hot air for 2 minutes. In the end, the sample surface was dry and uniform, and the coagulated structure was well exposed.

[0064] In one possible implementation, the cleaning operation in step S4 can be combined with auxiliary tools to improve cleaning efficiency. In the testing laboratories of some large steel companies, technicians use a rinsing device with adjustable water flow direction. The sample is fixed on the worktable of the device, and the water flow direction and speed are adjusted to ensure that clean water covers every corner of the test surface. During rinsing, the water flow direction can be set to diffuse from the center of the sample outwards, the flow rate is controlled at a medium level, and the rinsing time is about 2 minutes. Subsequently, an anhydrous ethanol is evenly sprayed onto the test surface using a cleaning tool equipped with an anhydrous ethanol nozzle, and wiped with a lint-free cloth for about 40 seconds. Finally, a hot air drying device with temperature control function is used, with the air temperature set at 40 to 50 degrees Celsius, the air outlet about 10 cm away from the sample surface, and the drying time is about 1.5 minutes. In a batch test, technicians used the above equipment to clean and dry 10 samples. The surface of each sample reached a dry and clean state, and the coagulated structure was exposed in a consistent manner, significantly improving the operation efficiency.

[0065] For example, in practical applications, the details of the cleaning operation can be optimized according to the degree of corrosion on the sample surface. For samples with deeper corrosion, since there may be more reaction products remaining on the surface, the rinsing time with clean water can be increased to 3 minutes, and the test surface can be gently brushed with a soft brush during the rinsing process to remove stubborn residues. For samples with shallower corrosion, the rinsing time can be controlled within 1 minute to avoid excessive rinsing that could damage the surface structure. When rinsing with anhydrous ethanol, if slight liquid residue is found on the sample surface, the number of wipes can be increased to 2, each time for about 30 seconds, to ensure that the surface is thoroughly cleaned. In one test, technicians cleaned a sample with deep corrosion by first rinsing it with clean water for 2.5 minutes and gently brushing the surface with a soft brush for about 30 seconds, then wiping it twice with anhydrous ethanol for 30 seconds each time, and finally drying it with hot air for 1.5 minutes. The final sample surface was clean and dry, and the coagulated structure was clearly visible.

[0066] In another embodiment, the drying operation in step S4 can be adjusted according to environmental conditions. In high-humidity environments, such as when laboratory humidity exceeds 80% during the rainy season, hot air drying may not completely remove surface moisture. In this case, after drying, the sample can be placed in a drying oven and dried at 40 degrees Celsius for 10 minutes to ensure the surface is thoroughly dry. In low-temperature environments, such as when laboratory temperature is below 10 degrees Celsius in winter, the hot air temperature of the blower can be increased to 50 degrees Celsius, and the drying time extended to 3 minutes to accelerate moisture evaporation. In one test, after cleaning the sample in a high-humidity environment, the technician first dried it with hot air for 2 minutes, then placed the sample in a drying oven for 10 minutes. Ultimately, there was no moisture residue on the sample surface, and the coagulated structure was well revealed. This flexible adjustment method can achieve ideal drying results under different environmental conditions.

[0067] It is important to note that the success of the cleaning and drying process directly affects the image quality of subsequent photographic recordings. Incomplete cleaning can result in blurred images due to residual etchant or moisture, hindering the observation of the solidified microstructure. Therefore, in practice, it is recommended to flexibly adjust the cleaning and drying parameters based on the sample characteristics and environmental conditions. Furthermore, the cleaning effect should be judged by observing the sample surface condition; if residues or moisture are found, additional cleaning or drying should be performed promptly. During testing at a steel company, technicians, through multiple experiments, determined a cleaning and drying procedure suitable for specific environmental conditions. This included rinsing with clean water for 2 minutes, wiping with anhydrous ethanol for 40 seconds, and drying with hot air for 2 minutes. This ultimately achieved thorough cleaning and drying of the sample surface, providing high-quality samples for subsequent testing.

[0068] Step S5 involves photographing the solidified microstructure of the sample using a high-definition camera. The purpose of this step is to record the morphology of the solidified microstructure exposed on the sample's testing surface using high-definition imaging technology, providing intuitive data support for subsequent microstructure analysis and quality assessment. Photo recording is the final step in the entire non-destructive testing process and directly determines the visualization effect and analytical accuracy of the test results. During operation, attention must be paid to lighting conditions, camera parameter settings, and the selection of the shooting angle to ensure image clarity and a complete representation of the microstructure.

[0069] In one possible implementation, step S5 can be further refined into multiple sub-steps to ensure the quality of the photographic recording. Step S51: Locate the solidified structure of the dried sample in a well-lit location. During operation, it is recommended to place the sample on a light-uniform, shadow-free imaging platform. The ambient light should be natural light or soft white light, avoiding direct strong light that could cause glare or shadows. Step S52: Use a high-definition camera to photograph and record the macroscopic morphology of the solidified structure. During shooting, the camera lens should be perpendicular to the sample detection surface, and the focal length adjusted to cover the entire detection surface, recording the overall structure distribution on the sample surface. Step S53: Use a high-definition camera to photograph and record the microscopic morphology of the solidified structure. During shooting, the camera focal length can be adjusted or a macro lens can be used to focus on specific areas of the sample surface, such as areas with obvious dendritic structures or grain boundaries, recording microscopic details. Step S54: Obtain the solidified structure image from the photographic recording for subsequent analysis. Through the above steps, both the macroscopic and microscopic morphologies of the sample's solidified structure are completely recorded, providing rich image data for subsequent quality assessment.

[0070] For example, in the testing laboratory of a steel company, after cleaning and drying the samples, technicians placed them on a photographing platform equipped with uniform white light. The light angle was adjusted so that the light shone from both sides of the sample at a 45-degree angle to avoid surface reflection. Then, using a high-definition camera with a resolution of at least 20 megapixels, the lens was held perpendicular to the sample's testing surface, and the focus was adjusted to photograph the entire testing surface, recording the macroscopic morphology of the solidified structure. The distribution of dendritic structures was clearly shown in the image. Next, the camera was switched to macro mode, focusing on the central region of the sample to photograph the microscopic morphology. Grain boundary lines and fine dendrite structures were clearly visible in the image. After shooting, the images were saved to a computer for subsequent microstructure analysis. This method demonstrated good imaging results in multiple experiments, ensuring a complete record of the solidified structure morphology.

[0071] In another embodiment, the parameters and methods for photographing and recording oriented silicon steel billet samples of different specifications can be appropriately adjusted. For samples with a large area, such as those with a test surface area exceeding 100 square centimeters, a segmented shooting method can be used, dividing the test surface into multiple regions and photographing the macroscopic morphology of each region one by one to ensure that the microstructure of each region is completely recorded. For samples with a small area, such as those with a test surface area less than 50 square centimeters, the entire test surface can be photographed at once, reducing the number of operation steps. When photographing the microstructure, if there are multiple key areas on the sample surface, such as significant differences in microstructure between the center and the edge, macroscopic images can be taken of each region separately to record the microscopic details of different parts. In one test, technicians used segmented shooting on a sample with an area of ​​approximately 120 square centimeters, dividing the test surface into four regions, taking a macroscopic morphology image of each region, and then taking a macroscopic image of the center and the edge, ultimately obtaining comprehensive solidification microstructure data.

[0072] In one possible implementation, the photographic recording in step S5 can be combined with auxiliary equipment to improve image quality. In certain high-precision testing scenarios, technicians use a high-definition camera with a tripod and adjustable angle to fix the sample on the imaging stage. The camera height and angle are adjusted using the tripod to ensure the lens is completely perpendicular to the testing surface, avoiding image distortion. During shooting, a remote shutter or timer function can be used to reduce hand-held shaking. Additionally, a ring light can be placed around the imaging stage to provide uniform and soft lighting, avoiding shadow interference. When photographing the microstructure, an external microscope lens can be connected, with magnification adjusted to 10 to 20 times, focusing on the fine structure of the sample surface and recording the detailed features of grain boundaries and dendrites. In one test, technicians used the above equipment to photograph the sample; the macroscopic morphology image clearly presented the overall tissue distribution, and the grain boundary lines were finely visible in the microscopic morphology image, providing high-quality image support for subsequent analysis.

[0073] For example, in practical applications, the details captured in photographs can be optimized based on the detection target. If the detection target is to analyze the macroscopic distribution of solidified structures, the camera focal length can be adjusted to wide-angle mode to capture images covering the entire detection surface, focusing on recording the overall morphology and distribution patterns of the dendrite structure. Conversely, if the detection target is to analyze microscopic grain boundary features, macro mode or a microscope lens should be used to focus on a specific area, capturing multiple high-magnification images to record the morphological characteristics of grain boundary lines and fine dendrites. In one detection, technicians captured macroscopic and microscopic morphology images of two samples, depending on the detection target. One sample was captured with a wide-angle image covering the entire detection surface, clearly showing the dendrite distribution; the other sample was captured with a 10x magnified image of the central area, revealing the grain boundary details clearly, thus meeting different analytical needs.

[0074] In another embodiment, the lighting conditions in step S5 can be adjusted according to environmental conditions. In indoor environments with insufficient natural light, such as at night or on cloudy days, a supplementary light equipped with color temperature adjustment can be used, with the color temperature set between 5000 and 5500 Kelvin to simulate natural white light and ensure accurate image colors. In environments with excessively strong light, such as outdoor scenes with direct sunlight, a light-blocking cloth can be placed above the shooting platform to reduce the interference of strong light reflections on the sample surface. If slight reflections are still found on the sample surface during shooting, the light angle can be adjusted or a polarizing filter can be added in front of the lens to eliminate the reflection effect. In one test, technicians used a supplementary light with a color temperature of 5200 Kelvin to photograph the sample in an indoor environment with insufficient light. The image colors were natural, and the solidified structure was clearly visible, achieving the expected imaging effect.

[0075] It should be noted that photographic recording, as the final step in the entire testing process, directly impacts the accuracy of subsequent analysis due to its image quality. Therefore, in practice, it is recommended to flexibly adjust camera parameters, lighting conditions, and shooting methods based on sample characteristics and testing objectives. Simultaneously, pre-shooting test images should be conducted to assess image quality. If blurring or glare is observed, equipment or the environment should be adjusted promptly to ensure the final image meets analytical requirements. In the quality inspection of a steel company, technicians, through multiple experiments, determined a shooting scheme suitable for specific-orientation silicon steel billets. This included using a tripod to fix the camera, setting up a ring light, and taking two images each of the macroscopic and microscopic morphology. Ultimately, this achieved high-quality recording of the solidification structure morphology, providing crucial data support for process optimization.

[0076] In one possible implementation, the image saving and processing in step S5 can also be optimized using digital tools. In some testing scenarios, after capturing images, technicians directly transfer them to a computer and use image processing software to make preliminary adjustments, such as adjusting brightness and contrast, to make the solidified structure more clearly visible. Furthermore, images can be annotated, for example, marking key areas on macroscopic morphology images or grain boundary features on microscopic morphology images, facilitating quick location of key information by subsequent analysts. When saving, it is recommended to store images in high-resolution format and back them up to multiple storage devices to avoid data loss. In a batch testing operation, technicians captured and processed solidified structure images of 20 samples. The brightness and contrast of each image were adjusted, and key areas were annotated. The resulting image data was intuitive and clear, facilitating subsequent analysis.

[0077] For example, in practical applications, the process of taking photos can be optimized based on the specific conditions of the laboratory. In some small laboratories with limited resources, high-end HD camera equipment may not be available. In such cases, ordinary digital cameras or mobile phone cameras can be used, but it is essential to ensure the lens is clean and to manually adjust the focus and lighting conditions to maximize image clarity. Furthermore, free image processing software can be used for post-processing adjustments after shooting, such as increasing brightness or sharpening image edges to make the solidified tissue structure more apparent. In a small laboratory test, technicians used a mobile phone camera to photograph the sample, adjusting the focus and lighting angle to capture clear macroscopic morphological images. Software was then used to enhance image contrast, ultimately obtaining solidified tissue image data suitable for analysis.

[0078] In another embodiment, the photographic recording in step S5 can be combined with multi-angle shooting to obtain more comprehensive tissue morphology data. In some high-requirement testing scenarios, when photographing the macroscopic morphology, technicians not only take vertical shots from directly above but also take multiple side views from a 45-degree angle to record the three-dimensional morphological characteristics of the solidified tissue at different angles. When photographing the microscopic morphology, macroscopic shots can be taken of the same area from multiple angles, such as one each from the front, side, and oblique views, to record the three-dimensional details of grain boundaries and dendrite structures. In one test, technicians took multi-angle shots of a sample, taking two images each from directly above and at a 45-degree angle for the macroscopic morphology, and one image each from three angles for the microscopic morphology of the central area. The resulting image data comprehensively presented the three-dimensional morphology of the solidified tissue, providing rich data support for subsequent three-dimensional analysis.

[0079] It should be noted that the quality of photographic recording is also closely related to the operator's experience and skills, especially in adjusting camera parameters and lighting conditions, which requires gradual mastery through repeated practice. Therefore, it is recommended that experienced operators be assigned to the shooting steps in actual operations, or that training and simulation exercises be used to improve the skill level of novice operators. In the testing process of a certain laboratory, technicians organized multiple shooting training sessions, enabling novice operators to gradually master the skills of lighting adjustment and focus control during practice before formal testing. Ultimately, they achieved imaging results similar to those of senior operators in the formal testing, ensuring the reliability of the image data.

[0080] In one possible implementation, the quality of the photographic record in step S5 can also be assessed by comparing it with historical image data. In the inspection departments of some steel companies, technicians compare the current image with high-quality images from previous inspections after each shot. If the current image is found to be insufficiently clear or the microstructure is not fully revealed, possible causes are analyzed, such as insufficient lighting or improper focus. Adjustments are then made and the image is retaken. In one inspection, technicians found a slight blurriness in the sample surface image. After comparing it with historical high-quality images, they determined that the focus adjustment was improper. The camera focus was then readjusted and additional shots were taken, ultimately achieving a clear effect similar to the historical images. This comparative assessment method can effectively improve image quality and ensure that each shot achieves the expected goal.

[0081] For example, in practical applications, the details captured in the photographs can be optimized based on the specific conditions of the testing environment. In some testing scenarios with complex lighting conditions, such as when there are many windows in a laboratory leading to uneven lighting, light-blocking curtains can be set up around the imaging table to block external light interference, while adjustable-brightness supplementary lights are used to ensure uniform and soft lighting. In one test, technicians photographed samples in an environment with uneven lighting. They first set up light-blocking curtains around the imaging table, and then used supplementary lights to adjust the brightness to a medium level. The final image was free of shadow interference, and the solidified tissue structure was clearly visible. This method is particularly suitable for testing scenarios with unstable lighting conditions and can effectively improve image quality.

[0082] In another embodiment, the photographic recording in step S5 can also be tailored to specific characteristics of the sample surface. In certain testing scenarios, if there are significant differences in the microstructure of the sample surface, such as dense dendrites in the central region and sparse dendrites in the peripheral region, the shooting focus can be adjusted based on these characteristics. More microscopic morphology images can be captured in the central region, and more macroscopic morphology images can be captured in the peripheral region to comprehensively record the microstructure characteristics of different regions. In one test, the technician found that the dendritic structure in the central region of the sample was complex. Subsequently, five macro images of this region at different magnifications were captured, and two wide-angle images of the peripheral region were captured. The resulting image data comprehensively reflected the differences in the microstructure distribution of the sample surface, providing targeted data support for subsequent analysis.

[0083] It should be noted that photographic recording, as the final presentation stage of the entire non-destructive testing process, directly affects the usability of the test results due to its operational details and image quality. Therefore, in practice, it is recommended to comprehensively consider various factors such as sample characteristics, testing targets, equipment conditions, and environmental factors, flexibly adjusting shooting parameters and methods. Furthermore, optimizing the imaging effect through pre-shooting, comparative evaluation, and multi-angle shooting is crucial to ensure a complete record of the solidification structure morphology. In the quality inspection of a steel company, technicians, through multiple experiments and parameter adjustments, finally determined a shooting operation plan suitable for specific orientation silicon steel billets. This included using a tripod to fix the camera, setting uniform supplementary lighting, and shooting images from multiple angles, successfully achieving high-quality recording of the solidification structure morphology and providing important reference for process improvement and quality assessment.

[0084] In one possible implementation, the subsequent image analysis in step S5 can be optimized by combining it with the detection target. In some detection scenarios, after taking pictures, technicians can classify and save the images according to the detection target. For example, macroscopic and microscopic morphology images can be stored in different folders, and the sample number and shooting area can be marked in the file name for easy retrieval later. In addition, simple analytical markers can be added to the images, such as arrows to mark key dendritic structures or grain boundary features, to help analysts quickly locate key areas. In a batch detection, technicians classified, saved, and labeled the solidification structure images of 30 samples. Each image was marked with the sample number and shooting location. The final image data was well-organized and facilitated subsequent analysis and comparison.

[0085] For example, in practical applications, the photo recording operation can be expanded according to the specific needs of the laboratory. In some testing scenarios that require long-term tracking of sample microstructure changes, technicians can compare the images with historical data after each shot to observe the changing trend of solidification microstructure over time or with process adjustments, and record the comparison results in the test report for process improvement reference. In a long-term test, technicians photographed the same batch of grain-oriented silicon steel billet samples at different time points, recording images of the solidification microstructure at the beginning, middle, and end of production. By comparison, they found that the dendritic structure gradually became more uniform with process optimization, providing a direct basis for subsequent production process adjustments.

[0086] In another embodiment, the efficiency of the photo recording in step S5 can be improved by combining it with digital management. In the testing departments of some large steel companies, after taking photos, technicians upload the image data to the company's internal digital testing system. The system automatically generates a test report, which includes information such as the sample number, shooting time, and image classification, and supports online viewing and sharing of the images. Furthermore, the system can perform preliminary image analysis, such as automatically identifying the main distribution areas of dendritic structures, assisting technicians in quickly completing preliminary assessments. In one test, technicians uploaded images of the solidification structure of 20 samples to the digital system, which automatically generated a test report containing image classification and preliminary analysis results, significantly improving data management efficiency.

[0087] It should be noted that the process of photographic recording is not limited to image acquisition, but also includes subsequent steps such as image storage, management, and preliminary analysis. These steps also significantly impact the completeness and usability of the test results. Therefore, in practice, it is recommended to flexibly select appropriate image processing and management methods based on the specific conditions of the laboratory and the testing needs, while further improving data utilization efficiency through digital tools or classification and labeling. In the quality inspection of a steel company, technicians integrated the process of capturing, storing, and analyzing solidification structure images into a complete workflow by introducing a digital management system. This ultimately achieved efficient management and rapid sharing of test data, providing strong support for quality control and process optimization.

[0088] In one possible implementation, the photographic recording in step S5 can also be performed collaboratively by multiple devices to improve imaging quality and efficiency. In certain high-requirement testing scenarios, technicians can use multiple high-definition cameras to simultaneously photograph different areas of the sample surface. For example, one camera can capture the macroscopic morphology, while another camera equipped with a macro lens captures the microscopic morphology. This multi-device collaborative operation shortens the shooting time. Furthermore, during the shooting process, a tablet or display screen can be used to view the camera footage in real time, allowing for timely adjustments to focus and lighting conditions to ensure image quality. In one testing instance, technicians used two high-definition cameras to photograph the sample: one capturing the entire testing surface, and the other focusing on the microstructure of the central area. Simultaneously, they viewed the footage in real time on a tablet, adjusting focus and lighting accordingly. The resulting image data was comprehensive and clear, reducing operation time by nearly half.

[0089] For example, in practical applications, the photographic recording operation can be tailored to the complexity of the sample surface. In detection scenarios where the sample surface exhibits multi-layered structures, such as complex intermingling of dendrites and grain boundaries, the number of shots and angles can be increased. Multiple images at different magnifications can be taken for each key area to ensure that all structural features are fully recorded. In one instance, technicians discovered a rich dendritic structure on the sample surface. Subsequently, three images at different magnifications were taken for the center, edge, and middle regions of the tested surface, for a total of nine images. The resulting image data comprehensively reflected the structural characteristics of the sample surface, providing detailed visual evidence for subsequent analysis.

[0090] In another embodiment, the photographic recording in step S5 can be combined with protective measures for the sample surface to avoid surface damage during the photographing process. In some testing scenarios, if dust or impurities are present in the shooting environment, they may fall onto the sample surface during the photographing process, affecting the imaging effect. In this case, a transparent protective cover can be set up around the shooting stage to block external impurities from interfering. In addition, if the shooting time is long, the sample can be covered with a lint-free cloth during the shooting intervals to avoid oxidation caused by prolonged surface exposure. In one test, the technician used a transparent protective cover to protect the sample surface during the photographing process and covered it with a lint-free cloth during the shooting intervals. Ultimately, the sample surface remained clean, the captured images were free of impurities, and the solidified structure was clearly visible.

[0091] The principle and steps of this invention are as follows: (1) Preparation of the etching agent. Prepare the etching agent by adding 1.2-1.5g of stannous chloride, 10-15g of anhydrous ferric chloride, 40-50ml of anhydrous ethanol, 15-20ml of hydrochloric acid (36wt%-38wt%), 0.3-0.4g of anhydrous copper chloride, 0.3-0.4g of anhydrous magnesium chloride, and 0.5-1g of sodium dodecylbenzenesulfonate per 100ml of deionized water. First, add stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride, and sodium dodecylbenzenesulfonate to the deionized water, and place it on a magnetic stirrer and stir for 2-4 minutes at a speed of 1000-1500 rpm until the stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride, and sodium dodecylbenzenesulfonate are completely dissolved in the deionized water. Then, add anhydrous ethanol and hydrochloric acid in sequence, place on a magnetic stirrer and stir for 1-2 minutes at a speed of 1000-1500 rpm, then remove and set aside. (2) Surface pretreatment of the test sample. The test surface of the cast billet sample is ground to a smooth surface with Ra=0.4~0.6μm, and then the smooth surface of the sample is wiped with anhydrous ethanol to remove oil stains; (3) Wiping and etching. Use tweezers to hold a cotton ball soaked in etchant and wipe the test surface of the sample evenly. The etching time is 15~30s; (4) Sample cleaning. After etching, place the sample in a water tank and rinse the test surface with running water in one direction. After taking it out, rinse the test surface with anhydrous ethanol in the same direction and dry it with a hair dryer on hot air. (5) Recording of solidification structure. In a well-lit location, use a high-definition camera to photograph and record the solidification structure of the sample.

[0092] Example 1 A non-destructive testing method for the solidification structure of grain-oriented silicon steel for high-voltage transformers is disclosed. The slab is produced by a slab continuous casting machine, the steel grade is grain-oriented silicon steel for high-voltage transformers, the casting speed is 1.3 m / min, the superheat is 19℃, the S-EMS current is 400 A, the cross-section is 1250 mm × 230 mm, and the chemical composition is shown in Table 1. The method includes the following steps: (1) Preparation of the etching agent. First, take 1.2g of stannous chloride, 15g of anhydrous ferric chloride, 0.35g of anhydrous copper chloride, 0.35g of anhydrous magnesium chloride, and 0.5g of sodium dodecylbenzenesulfonate and add them to 100ml of deionized water. Place the mixture on a magnetic stirrer and stir for 2min at a speed of 1200 rpm until the stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride, and sodium dodecylbenzenesulfonate are completely dissolved in the deionized water. Then, add 50ml of anhydrous ethanol and 15ml of hydrochloric acid in sequence, place the mixture on a magnetic stirrer and stir for 2min at a speed of 1200 rpm. Remove the mixture and set it aside. (2) Surface pretreatment of the test specimen. The test surface of the cast billet specimen is ground and machined into R. a The sample surface has a thickness of 0.6 μm, and then the oil stains are removed by wiping the smooth surface of the sample with anhydrous ethanol. (3) Wiping etching. Use tweezers to hold a cotton ball soaked in etchant and wipe the test surface of the sample evenly. The etching time is 20 seconds. (4) Sample cleaning. After etching, place the sample in a water tank and rinse the test surface with running water in one direction. After taking it out, rinse the test surface with anhydrous ethanol in the same direction and dry it with a hair dryer on hot air. (5) Recording of solidification structure. In a well-lit location, a high-definition camera was used to photograph and record the solidification structure of the sample. The macroscopic morphology after erosion is shown below. Figure 1 As shown, the microstructure of the solidification structure of the cast billet at different locations from the inner arc is as follows: Figure 2 As shown, non-destructive testing of the solidification structure of grain-oriented silicon steel for high-voltage transformers is achieved.

[0093] Table 1 Typical chemical composition of grain-oriented silicon steel for high-voltage transformers C / % Si / % Mn / % P / % S / % Al / % 0.045 3.25 0.08 0.02 0.01 0.026 Example 2 A non-destructive testing method for the solidification structure of grain-oriented silicon steel for high-voltage transformers is disclosed. The slab is produced by a slab continuous casting machine, the steel grade is grain-oriented silicon steel for high-voltage transformers, the casting speed is 1.3 m / min, the superheat is 21℃, the S-EMS current is 0 A, the cross-section is 1250 mm × 230 mm, and the chemical composition is shown in Table 2. The method includes the following steps: (1) Preparation of the etching agent. Take 1.5g of stannous chloride, 12g of anhydrous ferric chloride, 0.3g of anhydrous copper chloride, 0.3g of anhydrous magnesium chloride, and 0.5g of sodium dodecylbenzenesulfonate and add them to 100ml of deionized water. Place the mixture on a magnetic stirrer and stir for 2min at 1200 rpm until the stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride, and sodium dodecylbenzenesulfonate are completely dissolved in the deionized water. Then, add 50ml of anhydrous ethanol and 18ml of hydrochloric acid in sequence, place the mixture on a magnetic stirrer and stir for 2min at 1200 rpm. Remove and set aside. (2) Surface pretreatment of the test specimen. The test surface of the cast billet specimen is ground and machined into R. a The sample surface has a thickness of 0.6 μm, and then the oil stains are removed by wiping the smooth surface of the sample with anhydrous ethanol. (3) Wiping etching. Use tweezers to hold a cotton ball soaked in etchant and wipe the test surface of the sample evenly. The etching time is 25 seconds. (4) Sample cleaning. After etching, place the sample in a water tank and rinse the test surface with running water in one direction. After taking it out, rinse the test surface with anhydrous ethanol in the same direction and dry it with a hair dryer on hot air. (5) Recording of solidification structure. In a well-lit location, a high-definition camera was used to photograph and record the solidification structure of the sample. The macroscopic morphology after erosion is shown below. Figure 3 As shown, the microstructure of the solidification structure of the cast billet at different locations from the inner arc is as follows: Figure 4 As shown, non-destructive testing of the solidification structure of grain-oriented silicon steel for high-voltage transformers is achieved.

[0094] Table 2 Typical Chemical Compositions of Grain-Oriented Silicon Steel for High-Voltage Transformers C / % Si / % Mn / % P / % S / % Al / % 0.046 3.24 0.09 0.021 0.009 0.027 The etching solution used in this invention has stable performance, readily available raw materials, short etching time, and no need for heating. Combined with standardized etching operation procedures, it can achieve non-destructive characterization of the solidification structure of grain-oriented silicon steel for high-voltage transformers. The outlines of primary and secondary dendrite structures are clear, facilitating statistical analysis of the microstructure of the billet. It can provide technical basis for optimizing the on-site continuous casting process and controlling the solidification structure of the billet.

[0095] The above provides a detailed description of an etchant, its preparation method, and the non-destructive testing method for solidification microstructure of grain-oriented silicon steel, as provided in the embodiments of this application. The descriptions of the embodiments above are merely illustrative of the methods and core concepts of this application; furthermore, those skilled in the art will recognize that variations in specific implementation methods and application scope may occur based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0096] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0097] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0098] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0099] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method for preparing an etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel, characterized in that, The preparation method includes the following steps: S1: Add stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride and sodium dodecylbenzenesulfonate to deionized water and stir to dissolve; S2: Add anhydrous ethanol and hydrochloric acid to deionized water in sequence, and continue stirring to obtain the etchant.

2. The method for preparing the etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel according to claim 1, characterized in that, S1 specifically includes: S11: Add stannous chloride, anhydrous ferric chloride, anhydrous copper chloride, anhydrous magnesium chloride and sodium dodecylbenzenesulfonate to deionized water, and use a magnetic stirrer to stir the solid components in the deionized water at a preset speed until the solid components are completely dissolved to obtain the first solution. S12: Add anhydrous ethanol to the first solution and stir to obtain a second solution; add hydrochloric acid to the second solution and stir to obtain the etchant; S13: Obtain the first solution from the deionized water for subsequent addition of anhydrous ethanol.

3. The method for preparing the etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel according to claim 2, characterized in that, In step S11, a magnetic stirrer is used to stir the solid components in the deionized water at a preset speed until the solid components are completely dissolved to obtain a first solution; in step S12, anhydrous ethanol is added after determining the dissolution state from the first solution.

4. The method for preparing the etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel according to claim 2, characterized in that, The stirring time on the magnetic stirrer in S11 is 2-4 minutes, and the speed is set at 1000-1500 rpm.

5. The method for preparing the etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel according to claim 1, characterized in that, The stirring time on the magnetic stirrer in S2 is 1~2 minutes, and the speed is set to 1000~1500 rpm.

6. The method for preparing the etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel according to claim 1, characterized in that, The ratio of S1 and S2 is as follows: per 100 ml of deionized water, add 1.2-1.5 g of stannous chloride, 10-15 g of anhydrous ferric chloride, 40-50 ml of anhydrous ethanol, 36 wt%-38 wt% of hydrochloric acid, 15-20 ml of anhydrous copper chloride, 0.3-0.4 g of anhydrous magnesium chloride, and 0.5-1 g of sodium dodecylbenzenesulfonate.

7. An etchant for non-destructive testing of the solidification structure of grain-oriented silicon steel, characterized in that, The etchant used for non-destructive testing of the solidified structure of grain-oriented silicon steel is prepared by the method for preparing the etchant for non-destructive testing of the solidified structure of grain-oriented silicon steel according to any one of claims 1-6.

8. A non-destructive testing method for the solidification structure of grain-oriented silicon steel, characterized in that, The non-destructive testing method for the solidified structure of oriented silicon steel is achieved by using the etchant described in claim 7 for non-destructive testing of the solidified structure of oriented silicon steel.

9. The non-destructive testing method for the solidification structure of grain-oriented silicon steel according to claim 8, characterized in that, The non-destructive testing method for the solidification structure of the grain-oriented silicon steel specifically includes: Preparation of etchant; (2) Surface pretreatment of the test sample: the test surface of the cast billet sample is ground into a smooth surface with Ra=0.4~0.6μm, and then the smooth surface of the sample is wiped with anhydrous ethanol to remove oil stains; (3) Wiping and erosion: Use tweezers to hold a cotton ball soaked in erosion agent and wipe the test surface of the sample evenly. The erosion time is 15~30s. (4) Sample cleaning: After the etching is completed, put the sample into the water tank and rinse the test surface with running water in one direction. After taking it out, rinse the test surface with anhydrous ethanol in the same direction and dry it with a hair dryer with hot air. (5) Recording of solidified structure: In a well-lit location, use a high-definition camera to take pictures of the solidified structure of the sample.

10. The non-destructive testing method for the solidification structure of grain-oriented silicon steel according to claim 8, characterized in that, The results of photographing the solidified structure of the sample using a high-definition camera were used to analyze the solidified structure of the grain-oriented silicon steel, thus completing the non-destructive testing.

Images