An etchant and etching method for displaying solidified dendrite structure of medium and high-grade non-oriented silicon steel

Abstract

The invention discloses an etchant and an erosion method for displaying the solidified dendrite structure of medium and high-grade non-oriented silicon steel, belonging to the technical field of metallographic inspection and analysis. The composition and proportion of the etching agent are: 1.5-2.0 g of picric acid, 35-50 ml of distilled water, 0.4-0.6 ml of hydrochloric acid, 0.3-0.5 g of anhydrous copper chloride, and 0.5-1 g of sodium dodecylbenzenesulfonate. The etching method of this etchant: first heat the prepared etchant to boiling state, then place the processed sample with the polished side down and suspend it in the etchant for 8-15s; Rinse the eroded surface with water and wipe it with a cotton ball; then polish the sample at 1 / 2 radius of the polishing machine for 5-10 seconds. The invention has short erosion time and simple operation procedures; it can quickly observe the clear primary and secondary solidification dendrite structures of medium and high-grade non-oriented silicon steel, thereby providing a technical basis for optimizing its continuous casting process and increasing the proportion of equiaxed crystals in casting slabs.

Description

Technical field [0001] The invention belongs to the technical field of metallographic inspection and analysis, and specifically relates to an etchant for displaying the solidified dendritic structure of non-oriented silicon steel of medium and high grades and a display method. Background technique [0002] Due to the high content of silicon and aluminum in medium and high grade non-oriented silicon steel, the cast slab mainly grows in the form of dendrites during the solidification process, so coarse columnar crystals will be formed. This columnar crystal is not easy to undergo α-γ phase transition during hot rolling, and the dynamic recovery and recrystallization are very slow, so it is difficult to be completely broken, which leads to the formation of coarse and elongated deformed grains, especially near the thickness center of the hot rolled sheet , And it is difficult to recrystallize in the subsequent cold rolling and annealing process, so it appears as a corrugated defect m...

AI Technical Summary

Problems solved by technology

The etchant containing picric acid has weak corrosion ability and long corrosion time. It is often necessary to add ferric chloride at the same time to improve its corrosion ability. Due to the strong corrosion ability of ferric chloride, it often causes serious damage to the secondary dendrites; Copper etchant, always forms a layer of copper deposits on the eroded surface to cover the dendrites after erosion, and needs to be removed with ammonia solution. After removing the film, it will not only destroy the dendrites, but also reduce The surface cleanliness of the dendrite structure affects the display effect

Using the above four dendrite etchants and corresponding methods to etch the structure of medium and high grade non-oriented silicon steel slabs, either the primary or secondary dendrite structure cannot be corroded, or the display effect is very poor.

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