In-situ observation method for morphology of non-metallic inclusions in ultra-pure non-oriented cold-rolled silicon steel

Abstract

The invention relates to an in-situ observation method for morphology of non-metallic inclusions in ultra-pure non-oriented cold-rolled silicon steel, which comprises the following steps: preparing a non-oriented cold-rolled silicon steel sample, grinding a to-be-tested surface to 1000#, enabling the surface of the sample to be flat and smooth, and carrying out mechanical polishing and surface cleaning; subjecting the treated sample to electrochemical corrosion on an electrochemical workstation, wherein an electrolyte comprises 1-8 wt% of a chloride MCl solution and the balance deionized water, introducing CO2 gas until the solution is saturated, and adding a proper amount of NaHCO3 and triethanolamine as stabilizers to adjust the pH value and stabilize the pH value between 6.0 and 6.5; wherein the electrochemical setting parameters are as follows: the open circuit time is 0.5-2 hours, the potentiodynamic polarization measurement is as follows: the scanning rate is 0.1 mV / S-1.0mV / S, the test interval is VS.SCE-0. 8V-0.2 V, and the test temperature is 10-25 DEG C; washing the samples subjected to electrochemical corrosion in different intervals with deionized water, and blow-drying; carrying out in-situ observation and component analysis on the morphology of the non-metallic inclusion through a scanning electron microscope+a spectrometer.

Description

technical field [0001] The invention relates to the field of detection of non-metallic inclusions in ultra-pure metal materials, in particular to the in-situ observation of a very small amount of micron-scale inclusions in ultra-pure non-oriented cold-rolled silicon steel. Background technique [0002] Ultra-pure non-oriented cold-rolled silicon steel is a silicon alloy steel with a finished carbon content of less than 0.03%, and its finished product thickness is 0.2-0.7mm. Because it is widely used in engines, motors and various electrical instrument panels, it is required to have low iron loss and high magnetic induction to improve work efficiency. Studies have shown that the size of non-metallic inclusions in non-oriented cold-rolled silicon steel has the greatest impact on magnetic properties, especially small inclusions, which not only pin the domain wall movement, but also when their size is similar to the magnetic domain have the greatest impact on magnetic propertie...

AI Technical Summary

Problems solved by technology

[0003] With the improvement of metallurgical technology, the interior of the finished non-oriented cold-rolled silicon steel is relatively pure, and the larger-sized non-metallic inclusions can be well controlled, but it is still very difficult to find the small micron-sized and sub-micron-sized non-metallic inclusions. It is more difficult to observe the three-dimensional morphology of small non-metallic inclusions at different depths in situ

[0004] The traditional methods for characterizing non-metallic inclusions are: (1) Metallographic method: metallographic method is simple to operate, but ordinary metallographic method only conducts two-dimensional analysis of non-metallic inclusions on the surface, and cannot observe small micron-sized and sub-micron-sized non-metallic inclusions

(2) Transmission electron microscope + energy spectrometer analysis: non-metallic inclusions can be clearly observed and their structure and composition can be determined, but the transmission electron microscope has a large magnification and a small field of view, and it is difficult to find them by using extraction carbon complex and ion thinning Non-metallic inclusions in non-oriented cold-rolled silicon steel with relatively pure steel quality and complicated sample preparation

(3) Scanning electron microscope + energy spectrometer analysis: After the sample is corroded, the morphology of the non-metallic inclusions is analyzed, but the depth of the corroded sample cannot be well controlled, and only some corroded non-metallic inclusions on the surface can be observed thing

(4) Electrolysis, extraction + electron microscope observation: the advantage is that more comprehensive statistics and complete observation can be carried out, but the inclusions are not in the original state, and the preparation of samples is more complicated

(5) Acid dissolution method: use organic acid or inorganic acid to dissolve the matrix and extract some corrosion-resistant non-metallic inclusions. The disadvantage is that many unstable inclusions will be dissolved, so that the inclusions cannot be fully and accurately reflected the actual form of

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