1. An in-situ observation method for the morphology of non-metallic inclusions in ultra-pure non-oriented cold-rolled silicon steel is characterized by comprising the following steps:

(1) preparing a non-oriented cold-rolled silicon steel sheet sample, grinding a surface to be tested to 1000# with abrasive paper to ensure that the surface of the sample is smooth, and performing mechanical polishing and surface cleaning;

(2) and carrying out electrochemical corrosion on the treated sample on an electrochemical workstation, wherein the electrolyte is as follows: 1-8 wt% of chloride MCl solution and the balance of deionized water, and introducing CO₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine is used as a stabilizer to adjust the pH value of the solution and stabilize the solution at 6.0-6.5; electrochemical setting parameters: opening a circuit: 0.5-2 h, performing potentiodynamic polarization test: scanning rate: 0.10 mV/S-1.0 mV/S, test interval: VS, SCE-0.8V-0.2V, the test temperature is as follows: 10-25 ℃;

(3) washing and drying the sample subjected to electrochemical corrosion; and carrying out in-situ observation and component analysis on the appearance of the nonmetallic inclusion of the sample after electrochemical corrosion by using a scanning electron microscope and an energy spectrometer.

2. The method for in-situ observation of the morphology of nonmetallic inclusions in ultra-pure non-oriented cold rolled silicon steel according to claim 1, wherein in the step (2), M is one or more of Na, K, Zn, Fe and Mg, wherein MCl may be one or more of mixed solutions.

3. The method for in-situ observation of the morphology of nonmetallic inclusions in ultrapure, non-oriented cold-rolled silicon steel as set forth in claim 1, wherein in said step (2), CO is used₂Introducing for at least 6h to reach saturation.

4. The method for in-situ observation of the morphology of nonmetallic inclusions in ultra-pure non-oriented cold-rolled silicon steel according to claim 1, wherein in the step (2), a proper amount of NaHCO is added₃And when the pH value is adjusted by triethanolamine, carrying out real-time measurement by using a pH meter, and stabilizing the pH value between 6.0 and 6.5.

5. The method for in-situ observation of the morphology of nonmetallic inclusions in ultra-pure non-oriented cold-rolled silicon steel according to claim 1, wherein in the step (2), the scanning rate is divided into three intervals: 0.10-0.30 mV/S, 0.30-0.60 mV/S, 0.80-1.0 mV/S, and are selected within these intervals.

6. The in-situ observation method for the morphology of the nonmetallic inclusions in the ultrapure non-oriented cold-rolled silicon steel according to claim 5, characterized in that in the step (2), the test interval is VS, SCE-0.8V-0.6V, -0.6V-0.2V, -0.2V.

7. The in-situ observation method for the morphology of nonmetallic inclusions in ultra-pure non-oriented cold-rolled silicon steel according to claim 6, characterized in that in the step (2), the test interval is as follows: at VS, SCE-0.8V to-0.6V, the scanning rate is: 0.80-1.0 mV/S; the test interval is: at VS, SCE-0.6V to-0.2V, the scanning rate is: 0.30-0.60 mV/S; the test interval is: at VS, SCE-0.2V, the scanning rate: 0.10-0.30 mV/S.

8. The in-situ observation method of the morphology of nonmetallic inclusions in ultra-pure non-oriented cold-rolled silicon steel according to claim 7, characterized in that three samples are prepared in the step (1); in the step (2), the scanning rate of the sample 1 is as follows: 0.80-1.0 mV/S, the test interval is: v, SCE-0.8V to-0.6V potentiodynamic polarization test; the scan rate of sample 2 was: 0.80-1.0 mV/S, the test interval is: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.30-0.60 mV/S, the test interval is: v, testing the zeta potential polarization of VS, SCE-0.6V to-0.2V; the scanning rate of sample 3 was: 0.80-1.0 mV/S, the test interval is: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.30-0.60 mV/S, the test interval is: VS, SCE-0.6V to-0.2V potentiodynamic polarization test, and finally carrying out scanning speed as follows: 0.10-0.30 mV/S, the test interval is: and VS, SCE-0.2V potentiodynamic polarization test.

9. The in-situ observation method for the morphology of nonmetallic inclusions in ultra-pure non-oriented cold-rolled silicon steel according to claim 8, characterized in that in the step (3), the samples 1, 2 and 3 are lightly washed with deionized water and blown dry with cold air; the appearance of the non-metallic inclusion is observed by a scanning electron microscope, and the components of the non-metallic inclusion are determined by an energy spectrum.

Background

The ultra-pure non-oriented cold rolled silicon steel is a silicon alloy steel with the carbon content of a finished product lower than 0.03 percent, and the thickness of the finished product is 0.2-0.7 mm. Due to the wide application to engines, motors and various electrical instruments, it is required to have low iron loss and high magnetic induction strength to improve the working efficiency. Research has shown that the size of non-metallic inclusions in non-oriented cold-rolled silicon steel has the greatest influence on magnetic properties, and particularly, fine inclusions not only have a pinning effect on the movement of domain walls, but also have the greatest influence on magnetic properties when the size of the inclusions is close to that of magnetic domains.

With the improvement of metallurgical technology, the interior of the finished non-oriented cold-rolled silicon steel is relatively pure, large-size nonmetallic inclusions can be well controlled, but fine micron-scale and submicron-scale nonmetallic inclusions are still difficult to find, and the three-dimensional appearance of the fine nonmetallic inclusions at different depths is difficult to observe in situ.

The traditional methods for characterizing nonmetallic inclusions are as follows: (1) a metallographic method: the metallographic method is simple to operate, but the common metallographic method only performs two-dimensional analysis on nonmetallic inclusions on the surface and cannot observe fine micrometer-level and submicron-level nonmetallic inclusions. (2) Transmission electron microscope + energy spectrometer analysis: the non-metallic inclusions can be clearly observed and the structure and the components of the non-metallic inclusions can be determined, but the transmission electron microscope has large magnification and small field of view, the non-metallic inclusions in the non-oriented cold-rolled silicon steel with purer steel quality are difficult to find by using extraction carbon reformation and ion thinning, and the sample preparation is more complex. (3) Scanning electron microscope + energy spectrometer analysis: after the sample is corroded, the appearance of the nonmetallic inclusion is analyzed, but the depth of the corroded sample cannot be well controlled, and only a few corroded nonmetallic inclusions on the surface can be observed. (4) Electrolysis, extraction and electron microscope observation: the advantages are that more comprehensive statistics and complete observation can be carried out, but the inclusion is not in the in-situ state, and the preparation of samples is more complicated. (5) Acid dissolution: the matrix is dissolved by using organic acid or inorganic acid to extract some corrosion-resistant nonmetallic inclusions, and the defect that a plurality of unstable inclusions are dissolved, so that the actual form of the inclusions cannot be comprehensively and accurately reflected.

Disclosure of Invention

The invention aims to provide an in-situ observation method for the appearance of non-metallic inclusions in ultra-pure non-oriented cold-rolled silicon steel, which utilizes simple sample grinding and electrokinetic potential polarization test to control the dissolution amount of a matrix by controlling a test interval and a scanning rate, and combines a scanning electron microscope and an energy spectrometer to carry out in-situ observation and component analysis on small non-metallic inclusions at different depths.

The invention relates to an in-situ observation method for the morphology of non-metallic inclusions in ultra-pure non-oriented cold-rolled silicon steel, which comprises the following steps:

(1) preparing a non-oriented cold-rolled silicon steel sample, grinding the surface to be tested to 1000# by using sand paper to ensure that the surface of the sample is smooth, and performing mechanical polishing and surface cleaning;

(2) and carrying out electrochemical corrosion on the treated sample on an electrochemical workstation, wherein the electrolyte is as follows:1-8 wt% of chloride MCl solution and the balance of deionized water, and introducing CO₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine is used as a stabilizer to regulate the pH value and stabilize the pH value to 6.0-6.5; electrochemical setting parameters: opening a circuit: 0.5-2 h, performing potentiodynamic polarization test: scanning rate: 0.10 mV/S-1.0 mV/S, test interval: VS, SCE-0.8V-0.2V, the test temperature is as follows: 10-25 ℃;

(3) washing and drying the sample subjected to electrochemical corrosion; and carrying out in-situ observation on the appearance of the nonmetallic inclusion of the sample after the electrochemical corrosion by using a scanning electron microscope and an energy spectrometer.

The non-oriented cold-rolled silicon steel is thin, belongs to active corrosion steel, has no passivation phenomenon, provides a foundation for accelerated corrosion by using the potentiodynamic polarization method, uses chloride MCl as electrolyte, has no toxicity, no harm, low cost and no danger, and is introduced with saturated CO₂Corrosion can be further accelerated. And the nonmetallic inclusion and the matrix can form a galvanic cell, the metal matrix can be dissolved in an accelerated manner as a high-potential anode, and the dissolution of the metallic matrix can be further promoted by the potentiodynamic polarization of the anode, so that the appearance of the nonmetallic inclusion is completely presented.

Preferably, in the above method for in-situ observation of the morphology of non-metallic inclusions in the ultrapure non-oriented cold rolled silicon steel, in the step (2), M is one or more of Na, K, Zn, Fe and Mg, wherein MCl may be a mixed solution of one or more.

Preferably, in the above method for in-situ observation of morphology of non-metallic inclusions in ultrapure non-oriented cold rolled silicon steel, in the step (2), CO₂Introducing for at least 6h to reach saturation.

Preferably, in the in-situ observation method for the appearance of the non-metallic inclusions in the ultra-pure non-oriented cold-rolled silicon steel, in the step (2), a proper amount of NaHCO is added₃And when the pH value is adjusted by triethanolamine, carrying out real-time measurement by using a pH meter, and stabilizing the pH value between 6.0 and 6.5.

Preferably, in the above method for in-situ observation of morphology of non-metallic inclusions in ultrapure non-oriented cold-rolled silicon steel, in the step (2), the scanning rate is divided into three intervals: 0.10-0.30 mV/S, 0.30-0.60 mV/S, 0.80-1.0 mV/S, and are selected within these intervals.

Preferably, in the in-situ observation method for the morphology of the nonmetallic inclusion in the ultra-pure non-oriented cold-rolled silicon steel, in the step (2), the test interval is VS, SCE-0.8V-0.6V, -0.6V-0.2V, -0.2V.

Preferably, in the above in-situ observation method of the morphology of non-metallic inclusions in the ultrapure non-oriented cold rolled silicon steel, in the step (2), the test interval is: at VS, SCE-0.8V to-0.6V, the scanning rate is: 0.80-1.0 mV/S, the test interval is: at VS, SCE-0.6V to-0.2V, the scanning rate is: 0.30-0.60 mV/S, the test interval is: at VS, SCE-0.2V, the scanning rate: 0.10-0.30 mV/S.

Preferably, in the in-situ observation method for the morphology of the nonmetallic inclusion in the ultra-pure non-oriented cold-rolled silicon steel, three samples are prepared in the step (1); in the step (2), the scanning rate of the sample 1 is as follows: 0.80-1.0 mV/S, the test interval is: and V, SCE-0.8V to-0.6V potentiodynamic polarization test. The scan rate of sample 2 was: 0.80-1.0 mV/S, the test interval is: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.30-0.60 mV/S, the test interval is: and V, SCE-0.6V to-0.2V potentiodynamic polarization test. The scanning rate of sample 3 was: 0.80-1.0 mV/S, the test interval is: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.30-0.60 mV/S, the test interval is: VS, SCE-0.6V to-0.2V potentiodynamic polarization test, and finally carrying out scanning speed as follows: 0.10-0.30 mV/S, the test interval is: and VS, SCE-0.2V potentiodynamic polarization test.

Preferably, in the in-situ observation method for the morphology of the nonmetallic inclusion in the ultrapure non-oriented cold-rolled silicon steel, in the step (3), the samples 1, 2 and 3 are lightly washed by deionized water and dried by cold air. The shape of the non-metallic inclusion is observed by a scanning electron microscope, and the components of the non-metallic inclusion are determined by an energy spectrum.

The invention has the beneficial effects that: the method of the invention uses a dynamic electrodeThe chemical method accelerates the corrosion of the ultra-pure non-oriented cold-rolled silicon steel, and the appearance of the non-metallic inclusions in the ultra-pure non-oriented cold-rolled silicon steel is observed in situ by using a scanning electron microscope and an energy spectrometer. The method is simple to operate, the electrolyte is MCl, is nontoxic and harmless, and is matched with saturated CO₂The corrosion can be accelerated, and the size and the morphology of the non-metallic inclusions can be better observed by controlling the test interval and the scanning speed and carrying out in-situ observation on the non-metallic inclusions on the surface and the deep layer of the non-oriented cold-rolled silicon steel.

Drawings

FIG. 1 is a three-dimensional morphology of in-situ non-metallic inclusions observed in sample 1 in example 1 of the present invention.

FIG. 2 is a graph showing an energy spectrum of in-situ non-metallic inclusions observed in sample 1 according to example 1 of the present invention.

FIG. 3 is a three-dimensional morphology of in-situ non-metallic inclusions observed for sample 2 in example 2 of the present invention.

FIG. 4 is a graph showing an energy spectrum of in-situ non-metallic inclusions observed in sample 2 according to example 2 of the present invention.

FIG. 5 is a three-dimensional topographical view of in-situ non-metallic inclusions observed in sample 3 in example 3 of the present invention.

FIG. 6 is a graph showing an energy spectrum of in-situ non-metallic inclusions observed in sample 3 according to example 3 of the present invention.

Detailed Description

Example 1

By adopting the technical scheme of the invention, a 35TWV1900 high-grade non-oriented cold-rolled silicon steel product with the thickness of 0.35mm is analyzed, a sample is processed into the size of 20mm multiplied by 30mm, a test surface to be tested is respectively ground by 240#, 400#, 600#, 800#, 1000# abrasive paper, mechanical polishing is carried out, and the surface of the test surface is cleaned in an ultrasonic instrument by 99.99% alcohol. Performing potentiodynamic polarization experiments by using a three-electrode electrolytic cell (reference electrolysis: saturated calomel electrode, auxiliary electrode: metal platinum net) and an electrochemical workstation, wherein the electrolyte: 1000ml of deionized water was taken, 30g of NaCl was completely dissolved therein, and 6h of CO was introduced₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine as a stabilizer to adjust the pH to 6.2. Electrochemical setting parameters: opening a circuit:1h, potentiodynamic polarization test: the scanning rate is: 0.9 mV/S, test interval: VS, SCE-0.8V to-0.6V, the test temperature is: at 21 ℃. And (4) lightly washing the sample subjected to electrochemical corrosion with deionized water, and blow-drying with cold air to enable nonmetallic inclusions to be highlighted.

And (3) carrying out in-situ observation on the appearance of the measured electrochemical non-metallic inclusion through a scanning electron microscope, and carrying out elemental analysis on the non-metallic inclusion by using an energy spectrometer. Fig. 1 and 2 are a three-dimensional morphology and an energy spectrum, respectively, of a nonmetallic inclusion observed in example 1 of the present invention. The inclusion is irregular square, the size of the inclusion is about 1.5 mu m multiplied by 2 mu m embedded in a matrix which is just corroded at the outermost layer, the main elements of the inclusion are Al, N, Fe and Si (Fe is used as the matrix) shown in an energy spectrum, and the inclusion is a non-metallic inclusion AlN seen by combining the shape and the components.

Example 2

By adopting the technical scheme of the invention, a 35TWV1900 high-grade non-oriented cold-rolled silicon steel product with the thickness of 0.35mm is analyzed, a sample is processed into the size of 20mm multiplied by 30mm, a test surface to be tested is respectively ground by 240#, 400#, 600#, 800#, 1000# abrasive paper, mechanical polishing is carried out, and the surface of the test surface is cleaned in an ultrasonic instrument by 99.99% alcohol. Performing potentiodynamic polarization experiments by using a three-electrode electrolytic cell (reference electrolysis: saturated calomel electrode, auxiliary electrode: metal platinum net) and an electrochemical workstation, wherein the electrolyte: taking 1000ml of deionized water, completely dissolving 50g of KCl in the deionized water, and introducing CO for 6h₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine as a stabilizer to adjust the pH to 6.0. Electrochemical setting parameters: opening a circuit: 1.5h, the scanning rate is performed firstly: 0.9 mV/S, test interval: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.333 mV/S, test interval: VS, SCE-0.6V to-0.2V, the testing temperature is: at 22 ℃. And (4) lightly washing the sample subjected to electrochemical corrosion with deionized water, and blow-drying with cold air to enable nonmetallic inclusions to be highlighted.

And (3) carrying out in-situ observation on the appearance of the measured electrochemical non-metallic inclusion through a scanning electron microscope, and carrying out elemental analysis on the non-metallic inclusion by using an energy spectrometer. FIGS. 3 and 4 are a three-dimensional morphology and an energy spectrum, respectively, of the nonmetallic inclusions observed in example 2 of the present invention. As can be seen from the scanning picture, the size of the non-metallic inclusion is about 3 mu m multiplied by 4 mu m, the non-metallic inclusion is embedded in the matrix in an inverted cone shape, the main elements in the energy spectrum are Al, N and Fe (Fe is the matrix), and the non-metallic inclusion is presumed to be AlN by combining the appearance.

Example 3

By adopting the technical scheme of the invention, a 35TWV1900 high-grade non-oriented cold-rolled silicon steel product with the thickness of 0.35mm is analyzed, a sample is processed into the size of 20mm multiplied by 30mm, a test surface to be tested is respectively ground by 240#, 400#, 600#, 800#, 1000# abrasive paper, mechanical polishing is carried out, and the surface of the test surface is cleaned in an ultrasonic instrument by 99.99% alcohol. Performing potentiodynamic polarization experiments by using a three-electrode electrolytic cell (reference electrolysis: saturated calomel electrode, auxiliary electrode: metal platinum net) and an electrochemical workstation, wherein the electrolyte: 1000ml of deionized water are taken, and 60g of ZnCl are added₂Completely dissolved in the solution, and 6h CO is introduced₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine as a stabilizer to adjust the pH to 6.3. Electrochemical setting parameters: opening a circuit: 0.5 h, the scanning rate is firstly as follows: 0.9 mV/S, test interval: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.35 mV/S, test interval: VS, SCE-0.6V to-0.2V potentiodynamic polarization test, and finally carrying out scanning speed as follows: 0.2 mV/S, test interval: VS, SCE-0.2V electrokinetic potential polarization test, the test temperature is: at 22 ℃. And (4) lightly washing the sample subjected to electrochemical corrosion with deionized water, and blow-drying with cold air to enable nonmetallic inclusions to be highlighted.

And (3) carrying out in-situ observation on the appearance of the measured electrochemical non-metallic inclusion through a scanning electron microscope, and carrying out elemental analysis on the non-metallic inclusion by using an energy spectrometer. FIGS. 5 and 6 are a three-dimensional morphology and an energy spectrum, respectively, of a nonmetallic inclusion observed in example 3 of the present invention. As can be seen from the pictures, the nonmetallic inclusion is positioned at the deep layer of the corroded substrate, the size of the nonmetallic inclusion is about 2 microns multiplied by 3 microns, the nonmetallic inclusion is embedded in the substrate in a pentagonal shape, the main elements in the energy spectrum are Al, N and Fe (Fe is the substrate), and the nonmetallic inclusion is presumed to be AlN by combining the appearance.

Example 4

By adopting the technical scheme of the invention, a 35TWV1900 high-grade non-oriented cold-rolled silicon steel product with the thickness of 0.35mm is analyzed, a sample is processed into the size of 20mm multiplied by 30mm, a test surface to be tested is respectively ground by 240#, 400#, 600#, 800#, 1000# abrasive paper, mechanical polishing is carried out, and the surface of the test surface is cleaned in an ultrasonic instrument by 99.99% alcohol. Performing potentiodynamic polarization experiments by using a three-electrode electrolytic cell (reference electrolysis: saturated calomel electrode, auxiliary electrode: metal platinum net) and an electrochemical workstation, wherein the electrolyte: 1000ml of deionized water was taken, and 30g of MgCl was added₂Completely dissolved in the solution, and 6h CO is introduced₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine as a stabilizer to adjust the pH to 6.2. Electrochemical setting parameters: opening a circuit: 1.5h, the scanning rate is performed firstly: 0.95 mV/S, test interval: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning speed is as follows: 0.5 mV/S, test interval: VS, SCE-0.6V to-0.2V, the testing temperature is: at 22 ℃. And (4) lightly washing the sample subjected to electrochemical corrosion with deionized water, and blow-drying with cold air to enable nonmetallic inclusions to be highlighted.

Example 5

By adopting the technical scheme of the invention, a 35TWV1900 high-grade non-oriented cold-rolled silicon steel product with the thickness of 0.35mm is analyzed, a sample is processed into the size of 20mm multiplied by 30mm, a test surface to be tested is respectively ground by 240#, 400#, 600#, 800#, 1000# abrasive paper, mechanical polishing is carried out, and the surface of the test surface is cleaned in an ultrasonic instrument by 99.99% alcohol. Performing potentiodynamic polarization experiments by using a three-electrode electrolytic cell (reference electrolysis: saturated calomel electrode, auxiliary electrode: metal platinum net) and an electrochemical workstation, wherein the electrolyte: 1000ml of deionized water was taken, 60g of NaCl was completely dissolved therein, and 6h of CO was introduced₂The gas is saturated, and a proper amount of NaHCO is added₃And triethanolamine as a stabilizer to adjust the pH to 6.4. Electrochemical setting parameters: opening a circuit: 1h, the scanning rate is as follows: 1mV/S, test interval: VS, SCE-0.8V to-0.6V potentiodynamic polarization test, and then scanning at a scanning rate of: 0.333 mV/S, test interval: VS, SCE-0.6V to-0.2V potentiodynamic polarization test, and finally carrying out scanning speed as follows: 0.167 mV/S, test interval: VS, SCE-0.2V electrokinetic potential polarization test, the test temperature is: 24 ℃. And (4) lightly washing the sample subjected to electrochemical corrosion with deionized water, and blow-drying with cold air to enable nonmetallic inclusions to be highlighted.

The method has the advantages of simple sample preparation, simple operation, short period, low cost and high analysis speed, and can observe the in-situ morphology of nonmetallic inclusions at different depths and quickly determine the composition types of the nonmetallic inclusions.

The invention is not the best known technology.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.