Method for observing in-situ morphologies of nonmetallic inclusions in steel

Abstract

The invention relates to a method for observing the in-situ morphologies of the nonmetallic inclusions in steel. The method is characterized by comprising the following steps: a metallographic specimen is prepared and a surface to be observed is polished to be a plane; the superficial electrolytic corrosion is performed on an electrochemical polishing apparatus, an electrolyte is as follows: 5% (v/v) HCl (hydrogen chloride)+5%(v/v) glycerol+1% (v/v) citric acid methanol solution, and the setup parameters of the electrochemical polishing apparatus are as follows: the current density is 0.02A to 0.10A/cm<2>, the electrolytic temperature is from below 15 DEG C to below 5 DEG C, and the electrolytic time is 20 to 40s; a rubber rod is utilized for slightly wiping off the corrosive products on an electrochemical polishing surface of a test sample after the electrochemical polishing, the surface of the test sample is dried by a blow drier, and the nonmetallic inclusions are highlighted on an electrolytic etched surface of the test sample, so that the true morphologies of the nonmetallic inclusions with the different dimensions are completely displayed; and the morphologies of the nonmetallic inclusions are observed by a scanning electron microscope and an energy disperse spectroscopy. The method for observing in-situ morphologies of nonmetallic inclusions in steel provided by the invention has the advantages that the sample is prepared simply, the period is short, the analysis speed is fast, and the constituents and the varieties of the nonmetallic inclusions can be determined accurately by observing the three-dimensional morphologies and dimensions of the nonmetallic inclusions.

Description

technical field [0001] The invention belongs to the technical field of steelmaking and continuous casting, in particular to a method for observing the in-situ morphology of nonmetallic inclusions in steel. Background technique [0002] The type, shape, size and distribution of non-metallic inclusions in steel have an important impact on the properties of steel. How to effectively understand and improve the non-metallic inclusions in steel is very important, so the research technology of inclusions is more and more popular. world's high attention. With the improvement of clean steel smelting requirements, only by having an accurate understanding of the shape of non-metallic inclusions in steel can they be well controlled during the smelting process. The traditional methods for characterizing inclusions mainly include: (1) Electrolytic extraction + chemical analysis (EE+CA). Determine the total amount of inclusions and the composition of main elements. The sample size is 5-...

AI Technical Summary

Problems solved by technology

Advantages: Large sampling volume, representative of large and small particles, good content and composition analysis accuracy; Disadvantages: Requires high purity of reagents and long analysis cycle

Advantages: faster analysis speed, the inclusions are in situ; Disadvantages: two-dimensional analysis, not suitable for the analysis of fine inclusions (<0.5)

Advantages: It can measure fine inclusion particles with a scale of tens of nanometers; Disadvantages: Extraction (electrolysis or acid dissolution) and removal of carbides are time-consuming and may lose target inclusions, and inclusions are not in situ

Advantages: three-dimensional analysis, good accuracy; Disadvantages: long analysis period, non-situ state of inclusions

Advantages: Faster analysis speed; Disadvantages: Some inclusions may change their original shape and chemical composition due to aggregation

Advantages: It can measure fine inclusion particles with a scale of tens of nanometers; Disadvantages: Complicated sample preparation and long analysis time

Advantages: macroscopic analysis, the inclusions are in situ state, and the analysis speed is fast; Disadvantages: only particles above 30um can be detected

Advantages: Fast analysis speed; Disadvantages: No shape and size information, heating process may cause some inclusions to change

Advantages: fast analysis speed, macroscopic analysis; Disadvantages: less standard samples, not suitable for analysis of fine inclusions (<0.5um)

(11) There are many traditional methods for characterizing non-metallic inclusions, but it is not easy to observe and analyze the real three-dimensional shape of non-metallic inclusions in steel in situ

The metallographic method can only observe the two-dimensional morphology of the inclusions. Although the electrolysis method can extract the non-metallic inclusions in the steel, the morphology of the inclusions is easily destroyed during the electrolysis and elutriation process, and the target inclusions may be lost. There are disadvantages such as long electrolysis time, difficult operation, and ex-situ analysis

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