Method for removing deteriorated layer on stainless steel surface

Abstract

The invention relates to a method for removing a deteriorated layer on the surface of stainless steel, and relates to the technical field of polishing. The method is used for stainless steel subjected to hot isostatic pressing treatment and comprises the steps that a polishing solution is prepared and poured into a polishing tank; the polishing solution is heated to a preset temperature, and the stainless steel part is placed in the polishing groove and immersed in the polishing solution; the stainless steel part is subjected to polishing treatment according to preset voltage and preset time; wherein the polishing solution comprises a salt solution, an additive and water, the salt solution is at least two of potassium chloride, barium chloride and ammonium sulfate, and the additive is at least one of phosphoric acid, acetic acid, ethylene diamine tetra (methylene sodium phosphate) and sodium gluconate. The polishing solution prepared from the salt solution, the additive and the water can effectively remove a metamorphic layer on the surface of the stainless steel part, so that the size precision of the part subjected to hot isostatic pressing treatment can be accurately controlled, and the product is good in surface smoothness, flat, smooth and bright in color.

Description

technical field [0001] The invention relates to the technical field of polishing, in particular to a method for removing a degenerated layer on the surface of stainless steel. Background technique [0002] Stainless steel products are widely used, such as stainless steel powder metallurgy parts used in gas turbines. In order to meet various application requirements, it is necessary to ensure the excellent material properties of stainless steel powder metallurgy parts. For example, in order to improve the material properties of 316L stainless steel products produced by injection molding technology, it is necessary to use hot isostatic pressing technology, but after the product is subjected to high-temperature and high-pressure hot isostatic pressing, a certain thickness (about 10-15 μm) appears on the surface of the product. metamorphic layer. On the one hand, the composition of the metamorphic layer is complex, mainly oxides such as chromium oxide and nickel oxide, and the ...

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Problems solved by technology

However, after the pure ammonium sulfate solution is ionized, due to the ionization and gasification of water molecules in the later stage of polishing, the ion concentration increases in the later stage of polishing, the electric field strength between the two electrodes decreases, and the chemical pitting behavior of the base metal is more serious. A longer polishing time will affect the smoothness of the part surface. Accuracy and accuracy are compromised

After hot isostatic pressing of 316L stainless steel parts, the composition of the metamorphic oxide layer on the surface is complex. After high temperature and high pressure, the bonding force between the interface of the metamorphic layer and the substrate is strong, and the low-concentration salt solution cannot achieve simultaneous plasma removal and electrolytic etching at the beginning of polishing. , the removal of the metamorphic layer is insufficient; and the chemical erosion of the metamorphic layer on the surface of the part by the pure ammonium sulfate solution in the later stage of ionization cannot be carried out uniformly, the pitting behavior is serious, and the flatness of the part after polishing cannot be guaranteed

When the electrolyte plasma polishing solution is used to remove the surface metamorphic layer of 316L stainless steel parts after hot isostatic pressing, due to the complex composition of the metamorphic layer and the strong binding force between the interface and the substrate, the organic acid solution cannot quickly cause the molecular structure change of the surface metamorphic layer at the initial stage , the salt solution cannot quickly trigger the plasma discharge channel and reach a certain scale. In the later stage, the surface metamorphic layer will be removed unevenly. Continued polishing will lead to sand spots on the part of the metamorphic layer that has been removed. There are sand spots on the surface of the final 316L stainless steel parts. spot, uneven brightness

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