JP7145253B2 - Chemical polishing liquid and chemical polishing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a chemical polishing liquid used for chemical polishing of metals and a chemical polishing method of metals.

Carbon steel and alloy steel are important iron materials used in various industrial fields. Among them, SCM (chromium molybdenum steel), plastic mold steel equivalent to AISI-P20 and P21, Fe-Ni 36% Invar (registered trademark) characterized by low coefficient of thermal expansion, permalloy characterized by high initial permeability Among them, alloy steels such as Permalloy B and D, which have an iron content of over 50% by mass and are also used in vacuum equipment, and low-activation ferritic steel, which is promising for use in nuclear fusion reactors, have surface smoothness and surface smoothness depending on the application. Cleanliness is required. However, it is difficult to easily smooth the entire surface of parts that have been processed and molded into various and complicated shapes, and there are still many cases where the polishing is done manually, resulting in problems of high cost and extremely long work hours. exist. Therefore, development of appropriate surface treatment is demanded.

A number of chemical polishing solutions have been developed in order to address the above problems, but there is a problem that many of them contain hydrofluoric acid, which is a poison (Patent Document 1).

In addition, a chemical polishing liquid containing ammonium hydrogen fluoride and hydrogen peroxide instead of the poisonous hydrofluoric acid has been proposed (Patent Document 2). However, the effect of dissolving highly corrosion-resistant additive components (Cr, Mo, etc.) in alloy steel cannot be expected. This causes problems in achieving smoothing.

Patent No. 3105975 Patent No. 3144280

An object of the present invention is to provide a chemical polishing liquid and a chemical polishing method capable of smoothing the surface of metal. Another object of the present invention is to provide a chemical polishing liquid and a chemical polishing method capable of smoothing and glossing the surface of metal.

The inventor of the present invention has started studies with the aim of developing a chemical polishing liquid for chemically polishing metals. As a result of intensive investigation of the composition of the chemical polishing liquid, it was found that hydrogen peroxide and ammonium hydrogen fluoride, as well as phenyl glycol ethers such as diethylene glycol monophenyl ether, and chloride ions were blended to eliminate the need for hydrofluoric acid. It has also been found that the compound exhibits extremely excellent chemical polishing properties. The chemical polishing liquid having this composition was excellent in smoothing and brightening the surface of metals, and particularly excellent in smoothing and brightening the surface of alloy steel.

That is, the present invention is specified by the matters shown below.
(1) A chemical polishing liquid containing hydrogen peroxide, ammonium hydrogen fluoride, phenyl glycol ethers and chloride ions.
(2) The chemical polishing liquid according to (1) above, which is used for chemical polishing of alloy steel containing at least one selected from molybdenum, chromium and nickel.
(3) The chemical polishing liquid according to (1) or (2) above, wherein the content of hydrogen peroxide is 5 to 20% by mass.
(4) The chemical polishing liquid according to any one of (1) to (3) above, wherein the content of ammonium hydrogen fluoride is 0.5 to 10% by mass.
(5) The chemical polishing liquid according to any one of (1) to (4) above, wherein the content of the phenyl glycol ether is 0.1 to 5% by mass.
(6) The chemical polishing liquid according to any one of (1) to (5) above, wherein the content of chloride ions is 0.001 to 5% by mass.
(7) A chemical polishing method for a metal surface, which comprises bringing the chemical polishing liquid according to any one of (1) to (6) into contact with the metal surface.

A chemical polishing treatment using the chemical polishing liquid of the present invention can efficiently smoothen a metal surface. Further, when chemical polishing treatment is performed using the chemical polishing liquid of the present invention, the metal surface can be made glossy in addition to being smoothed.

FIG. 1(a) is a scanning electron microscope image of the chemically polished surface of the SCM440 plate milled in Example 3 of the present invention, and (c) is a scanning electron microscope image of the milled surface before chemical polishing. where (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 2(a) is a scanning electron microscope image of the chemically polished surface of a low-activation ferritic steel (F82H) plate milled in Example 27 of the present invention, and (c) is a milling before chemical polishing. It is a scanning electron microscope image of F82H of the cut surface, (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 3(a) is a scanning electron microscope image of the chemically polished surface of the milled plastic mold steel HPM1® plate in Example 28 of the present invention, and (c) is milling before chemical polishing. It is a scanning electron microscope image of HPM1 of the surface, (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 4(a) is a scanning electron microscope image of the chemically polished surface of plastic mold steel CENA1 (registered trademark) milled in Example 29 of the present invention, and (c) is the milled surface before chemical polishing. (b) is a surface roughness curve after chemical polishing, and (d) is a surface roughness curve before chemical polishing. FIG. 5(a) is a scanning electron microscope image of the chemically polished surface of plastic mold steel NAK55 (registered trademark) milled in Example 30 of the present invention, and (c) is the milled surface before chemical polishing. (b) is a surface roughness curve after chemical polishing, and (d) is a surface roughness curve before chemical polishing. FIG. 6(a) is a scanning electron microscope image of the chemically polished surface of Invar (registered trademark) milled in Example 31 of the present invention, and (c) is the Invar of the milled surface before chemical polishing. (b) is a surface roughness curve after chemical polishing, and (d) is a surface roughness curve before chemical polishing. FIG. 7(a) is a scanning electron microscope image of the chemically polished surface of the milled permalloy B plate in Example 32 of the present invention, and (c) is the permalloy B of the milled surface before chemical polishing. It is a scanning electron microscope image, (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 8(a) is a scanning electron microscope image of the chemically polished surface of the SCM440 plate milled in Comparative Example 1 of the present invention, and (c) is a scanning electron microscope image of the milled surface before chemical polishing. where (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 9(a) is a scanning electron microscope image of the chemically polished surface of the milled SCM440 plate in Comparative Example 2 of the present invention, and (c) is a scanning electron microscope image of the milled surface before chemical polishing. where (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 10(a) is a scanning electron microscope image of the chemically polished surface of the milled SCM440 plate in Comparative Example 3 of the present invention, and (c) is a scanning electron microscope image of the milled surface before chemical polishing. where (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 11(a) is a scanning electron microscope image of the chemically polished surface of the milled SCM440 plate in Comparative Example 5 of the present invention, and (c) is a scanning electron microscope image of the milled surface before chemical polishing. where (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing. FIG. 12(a) is a scanning electron microscope image of the chemically polished surface of the HPM1 plate milled in Comparative Example 6 of the present invention, and (c) is a scanning electron microscope image of the milled surface before chemical polishing. where (b) is the surface roughness curve after chemical polishing, and (d) is the surface roughness curve before chemical polishing.

The chemical polishing liquid of the present invention is characterized by containing hydrogen peroxide, ammonium hydrogen fluoride, phenyl glycol ethers and chloride ions. Phenyl glycol ethers in the present invention are not particularly limited, but examples include ethylene glycol monophenyl ether, diethylene glycol monophenyl ether, triethylene glycol monophenyl ether, tetraethylene glycol monophenyl ether, pentaethylene glycol monophenyl ether, Propylene glycol 2-monophenyl ether and the like can be mentioned. These may be used alone or in combination of two or more. Among them, at least one selected from ethylene glycol monophenyl ether and diethylene glycol monophenyl ether is preferable from the viewpoints of improvement in chemical polishing properties, availability and appropriateness of price. Due to their strong chelating action, phenyl glycol ethers have the effect of capturing transition metal ions dissolved from the metal to be polished in the chemical polishing liquid and suppressing the decomposition of hydrogen peroxide due to the catalytic action of the transition metal ions. However, as a result of research, not only that, but also the effect of improving the glossiness of the chemically polished surface of metal was found.

The source of chloride ions in the present invention is not particularly limited, but examples include hydrochloric acid, iron chloride (II), iron chloride (III), inorganic chlorides such as metal salts of chlorine, and the like. At least one selected from hydrochloric acid, iron (II) chloride and iron (III) chloride is preferable in consideration of the ability to etch metal and the pH reduction (maintenance of acidity) of the chemical polishing liquid. By containing chloride ions in addition to other components in the present invention, the chemical polishing liquid of the present invention can be chemically Since the segregated portions of these components, which are not dissolved by the polishing liquid and tend to segregate, can be dissolved, the chemical polishing treatment can make the surface microscopically smooth and provide excellent gloss. For example, when an alloy such as HPM1 in which Mo is segregated is chemically polished, if chloride ions are not present, the Mo segregation cannot be dissolved, and a remarkable convex portion is generated. , the presence of a small amount of chloride ions allows the Mo portion to dissolve. Furthermore, the dissolved Mo ions are deposited on the iron part according to the ionization tendency, so that the dissolution of the iron part by the chemical polishing liquid is suppressed, so to speak, the function of a "self-corrosion inhibitor" is exhibited. The content of hydrogen peroxide in the chemical polishing liquid of the present invention is preferably 4 to 25% by mass based on the entire chemical polishing liquid from the viewpoint of smoothing the metal surface. Further, from the viewpoint of evenly smoothing and glossing the metal surface and from the viewpoint of facilitating control of the reaction with the metal surface, the content is more preferably 5 to 20% by mass based on the entire chemical polishing liquid. The content of ammonium hydrogen fluoride in the chemical polishing liquid of the present invention is 0.00% relative to the entire chemical polishing liquid, from the viewpoints of having an appropriate reaction rate with the metal surface and from the viewpoint of dissolving the ammonium hydrogen fluoride. 5 to 10% by mass is preferable, and 1 to 5% by mass is more preferable. If the content of ammonium hydrogen fluoride is less than 0.5% by mass, the dissolution reaction of the metal in the chemical polishing liquid may be slowed. may not dissolve completely in The content of the phenylglycol ether in the chemical polishing liquid of the present invention is 0.00% relative to the entire chemical polishing liquid, from the viewpoint of making the metal surface more glossy and from the viewpoint of having an appropriate reaction rate with the metal surface. 1 to 5% by mass is preferred, and 1 to 5% by mass is more preferred. If the content of phenyl glycol ethers is less than 0.1% by mass, glossiness may become difficult, and if it exceeds 5% by mass, the dissolution reaction of the metal in the chemical polishing liquid may become slow. The content of chloride ions in the chemical polishing liquid of the present invention is preferably 0.001 to 5% by mass relative to the entire chemical polishing liquid from the viewpoint of being more suitable for mold steel and from the viewpoint of preventing pitting corrosion. .1 to 2.5% by mass is more preferable. If the chloride ion content is less than 0.001% by mass, the glossing effect may be reduced, and if it exceeds 5% by mass, pitting corrosion may occur. The chemical polishing liquid of the present invention is particularly suitable for chemical polishing of alloy steel containing at least one selected from molybdenum, chromium and nickel. Although these alloy steels are not particularly limited, for example, SCM (chromium molybdenum steel), SNCM (nickel chromium molybdenum steel), HPM1, CENA1, NAK55 and other AISI-P20 and P21 plastic mold steels, SKD61, which is an alloy tool steel, Invar, Permalloy B and D, low-activation ferritic steel such as F82H, and the like can be mentioned. Also, the chemical polishing liquid of the present invention can be suitably used for chemical polishing of alloy steel for molds. Examples of molds include plastic molds, press molds, die casting molds, casting molds, powder metallurgy molds, and the like. The contents of molybdenum, chromium and nickel contained in the alloy steel are not particularly limited as long as they are the amounts normally contained in various alloy steels. If the chromium content is high, the smoothing and brightening effects may be reduced, so an alloy steel with a chromium content of less than 10% by mass or less than 7% by mass is preferred. Also, from the viewpoint of smoothing and glossing, an alloy steel having a carbon content of less than 0.5% by mass is preferable.

The method for preparing the chemical polishing liquid of the present invention is not particularly limited. can be prepared by adding a chloride ion source such as iron (III) chloride and stirring appropriately. The chemical polishing method of the present invention chemically polishes the surface of the metal to be treated by bringing the surface of the metal to be treated into contact with the chemical polishing liquid of the present invention. While the chemical polishing liquid and the surface to be treated (the surface of the metal to be treated) are in contact with each other, the chemical polishing liquid or the surface to be treated may be oscillated as needed. For example, the surface to be treated may be immersed in a chemical polishing liquid and oscillated as appropriate. In addition, for example, when it is desired to chemically polish only the inner surface of a pipe-shaped object to be processed, it is also possible to carry out processing by feeding a chemical polishing liquid using a pump or the like. The temperature of the chemical polishing solution according to the chemical polishing method of the present invention can be polished without any particular heating, but it is preferably kept at 10°C to 50°C, more preferably 25°C to 40°C. If the temperature of the chemical polishing solution is lower than 10° C., the reactivity becomes slow, and the processing time required for obtaining a polishing effect becomes long, resulting in a decrease in workability. On the other hand, if the temperature of the chemical polishing liquid exceeds 50° C., the decomposition reaction of hydrogen peroxide, which is a component of the chemical polishing liquid, is accelerated, resulting in unnecessary deterioration of the chemical polishing liquid. The time for which the chemical polishing liquid of the present invention is brought into contact with the surface to be treated can be appropriately selected depending on the polishing conditions, and can be, for example, 1 minute to 1 hour. The chemical polishing method of the present invention is not particularly limited as long as the object to be treated is a metal, but it is particularly suitable for chemical polishing of alloy steel containing at least one selected from molybdenum, chromium and nickel. Although these alloy steels are not particularly limited, for example, SCM (chromium molybdenum steel), SNCM (nickel chromium molybdenum steel), HPM1, CENA1, NAK55 and other AISI-P20 and P21 plastic mold steels, SKD61, which is an alloy tool steel, Invar, Permalloy B and D, low-activation ferritic steel such as F82H, and the like can be mentioned.

The present invention will be further described below based on examples. However, the present invention is not limited to the embodiments shown in the examples.

（光沢）
光沢に関しては目視にて金属光沢を有するか否かで評価し、金属光沢を有する場合を評価〇とし、金属光沢を有さない場合を評価×とした。
（化学研磨効果）
表面粗度［Ｒａ］が化学研磨前に比べ改善し、かつ金属光沢が得られたものを化学研磨効果〇とし、化学研磨により表面粗度［Ｒａ］の改善又は金属光沢が得られたものを△とし、表面粗度［Ｒａ］の改善及び金属光沢どちらも達成できなかったものを化学研磨効果×とした。 [Evaluation method]
(Surface observation)
The evaluation of the surface was observed with a scanning electron microscope SU3500 (manufactured by Hitachi High-Technologies Corporation).
(smoothing)
Surface roughness [Ra] was obtained by measuring five arbitrary points with a surface roughness meter SURFCOM NEX001SD-12 (manufactured by Tokyo Seimitsu Co., Ltd.) and calculating the average value. In the evaluation of smoothing, the surface roughness reduction rate defined by the following formula (1) was evaluated as ◯ when it was +10% or more, and was evaluated as x when it was less than +10%. In the following formula (1), Ra1 represents the surface roughness before chemical polishing, and Ra2 represents the surface roughness after chemical polishing.

(gloss)
The luster was evaluated visually based on whether or not it had a metallic luster. The case with a metallic luster was evaluated as ◯, and the case with no metallic luster was evaluated as x.
(Chemical polishing effect)
The chemical polishing effect is ◯ when the surface roughness [Ra] is improved compared to before chemical polishing and metallic luster is obtained, and the surface roughness [Ra] is improved or metallic luster is obtained by chemical polishing. The chemical polishing effect was evaluated as Δ, and when neither improvement in surface roughness [Ra] nor metallic luster could be achieved, the chemical polishing effect was evaluated as x.

[Examples 1 to 6]
(Change in hydrogen peroxide concentration)
Hydrogen peroxide, ammonium hydrogen fluoride, diethylene glycol monophenyl ether, and hydrochloric acid are dissolved in water, and the concentration of ammonium hydrogen fluoride in the solution is 2.5% by mass, the concentration of diethylene glycol monophenyl ether is 3% by mass, and the chloride ion concentration is was set to 0.5% by mass, and the hydrogen peroxide concentration was changed as shown in [Table 1] to prepare chemical polishing solutions in Examples 1 to 6. About 400 mL of each prepared chemical polishing solution was filled in a polypropylene container, and a milled SCM440 plate (5 cm×5 cm, thickness 5 mm) was immersed in it for chemical polishing. The liquid temperature of the chemical polishing liquid was kept at 30±5° C., and the immersion time was 1 minute. The results of Examples 1 to 6 are shown in [Table 1].

[Examples 7-9]
(Change in ammonium hydrogen fluoride concentration)
Hydrogen peroxide, ammonium hydrogen fluoride, diethylene glycol monophenyl ether, and hydrochloric acid were dissolved in water, and the concentration of hydrogen peroxide in the solution was 10% by mass, the concentration of diethylene glycol monophenyl ether was 3% by mass, and the concentration of chloride ions was 0.5% by mass. Chemical polishing liquids in Examples 7 to 9 were prepared by changing the concentration of ammonium hydrogen fluoride to 5% by mass and changing the concentration as shown in [Table 2]. About 400 mL of each prepared chemical polishing solution was filled in a polypropylene container, and a milled SCM440 plate (5 cm×5 cm, thickness 5 mm) was immersed in it for chemical polishing. The liquid temperature of the chemical polishing liquid was kept at 30±5° C., and the immersion time was 1 minute. The results of Examples 7 to 9 are shown in [Table 2].

[Examples 10-12]
(Change in phenyl glycol ether concentration)
Hydrogen peroxide, ammonium hydrogen fluoride, diethylene glycol monophenyl ether and hydrochloric acid are dissolved in water, and the hydrogen peroxide concentration in the solution is 10% by mass, the ammonium hydrogen fluoride concentration is 2.5% by mass, and the chloride ion concentration is Chemical polishing liquids in Examples 10 to 12 were prepared by changing the concentration of diethylene glycol monophenyl ether as shown in [Table 3] with a concentration of 0.5% by mass. About 400 mL of each prepared chemical polishing solution was filled in a polypropylene container, and a milled SCM440 plate (5 cm×5 cm, thickness 5 mm) was immersed in it for chemical polishing. The liquid temperature of the chemical polishing liquid was kept at 30±5° C., and the immersion time was 1 minute. The results of Examples 10-12 are shown in [Table 3].

[Examples 13 to 15]
(Change of Phenyl Glycol Ether Species)
Hydrogen peroxide, ammonium hydrogen fluoride, phenyl glycol ether and hydrochloric acid are dissolved in water, and the hydrogen peroxide concentration in the solution is 10% by mass, the ammonium hydrogen fluoride concentration is 2.5% by mass, and the chloride ion concentration is 0. Chemical polishing liquids in Examples 13 to 15 were prepared by changing the type of phenylglycol ether as shown in [Table 4] and blending the phenylglycol ether concentration to 3% by mass. About 400 mL of each prepared chemical polishing solution was filled in a polypropylene container, and a milled SCM440 plate (5 cm×5 cm, thickness 5 mm) was immersed in it for chemical polishing. The liquid temperature of the chemical polishing liquid was kept at 30±5° C., and the immersion time was 1 minute. The results of Examples 13-15 are shown in [Table 4].

[Examples 16 to 23, Comparative Examples 1 to 5]
(Change in chloride ion concentration and change to other inorganic acids)
Hydrogen peroxide, ammonium hydrogen fluoride, diethylene glycol monophenyl ether, and hydrochloric acid, iron (III) chloride, sulfuric acid, nitric acid, or phosphoric acid are dissolved in water, and the concentration of hydrogen peroxide in the solution is 10% by mass, and the concentration of ammonium hydrogen fluoride is is 2.5% by mass, the diethylene glycol monophenyl ether concentration is 3% by mass, and the chloride ion concentration is changed as shown in [Table 5] to prepare chemical polishing liquids in Examples 16 to 23 and Comparative Examples 1 to 3. did. In Comparative Examples 1 to 3, the concentrations of sulfate ions, nitrate ions, and phosphate ions were adjusted to 1 mass %, respectively, and in Comparative Examples 4 and 5, no acid was added. About 400 mL of each prepared chemical polishing solution was filled in a polypropylene container, and in Comparative Examples 1 to 4, a milled SCM440 plate (5 cm × 5 cm, thickness 5 mm) was immersed to perform chemical polishing. A rolled sheet of HPM1 (5 cm x 5 cm, thickness 5 mm) was immersed and chemically polished. The liquid temperature of the chemical polishing liquid was kept at 30±5° C., and the immersion time was 1 minute. The results of Examples 16-23 and Comparative Examples 1-5 are shown in [Table 5]. Examples without hydrochloric acid could not be smoothed or brightened with sulfuric acid, nitric acid or phosphoric acid.

[Examples 3, 24 to 34]
(Applicable steel type)
Hydrogen peroxide, ammonium hydrogen fluoride, diethylene glycol monophenyl ether, and hydrochloric acid are dissolved in water, and the concentration of hydrogen peroxide in the solution is 10% by mass, the concentration of ammonium hydrogen fluoride is 2.5% by mass, and the concentration of diethylene glycol monophenyl ether is is 3% by mass, and the chemical polishing liquid with the chloride ion concentration adjusted to 0.5% by mass is used to chemically polish the steel grades as shown in [Table 6] (Examples 3, 24 to 34) is shown in [Table 6]. The liquid temperature of the chemical polishing liquid was kept at 35±5°C. FIG. 1 shows the results of electron microscope observation and surface roughness measurement of the surface of the metal sample before and after the treatment in Example 3, and FIG. 2 is the electron microscope of the surface of the metal sample before and after the treatment in Example 27. 3 shows the observation results and surface roughness measurement results of the metal sample surface before and after the treatment of Example 28 with an electron microscope, and FIG. 5 shows the results of electron microscope observation and surface roughness measurement results of the metal sample surface before and after treatment, and FIG. FIG. 6 shows the results of electron microscope observation and surface roughness measurement of the metal sample surface before and after the treatment of Example 31, and FIG. It is the observation result by an electron microscope of a sample surface, and a surface-roughness measurement result. In Examples 24 and 25, a heat-treated round bar with black scale (cross-sectional diameter 5 cm, thickness 1 cm) was used as a sample, and Example 26 was a heat-treated round bar with black scale (cross-sectional diameter 3 cm, thickness 1 cm). 1 cm) was used as a sample. Examples 27-30 were samples of rolled sheet (5 cm x 5 cm, 5 mm thick), and Examples 31-33 were samples of milled plate (10 cm x 10 cm, 1 cm thick). In Example 34, a heat-treated round bar with black scale (cross-sectional diameter: 5 cm, thickness: 1 cm) was used as a sample. From the results of the examples, the use of the chemical polishing liquid of the present invention makes it possible to achieve microscopic smoothing and gloss without leaving any segregation of corrosion-resistant components.

Table 7 summarizes the surface roughness [Ra] before and after chemical polishing, surface roughness reduction rate, and chemical polishing effect of Examples 1 to 34 and Comparative Examples 1 to 5. In Examples 1 to 34, the surface roughness reduction rate was +20% or more, which exceeded the surface roughness reduction rate +10% or more at which the smoothing evaluation was ◯.

Table 8 summarizes the main components of each steel material and the effects of chemical polishing.

The chemical polishing liquid and chemical polishing method of the present invention are not limited, but include steel with a carbon content of less than 0.5% by mass, SCM, plastic mold steel equivalent to AISI-P20 or P21, Invar, Permalloy B and D, alloy steel and low-activation ferritic steel can be efficiently chemically polished, and the metal surfaces of these can be smoothed and polished, so for example, improvement of transportation efficiency by smoothing the surface of an impeller for fluid transportation, Improvement in bonding strength can be expected by various bonding methods. It is also suitable for surface treatment in various industrial fields, such as improving the cleanliness and removing burrs of Invar used for vapor deposition masks in organic EL panel manufacturing equipment, permalloy magnetic shield chambers, and improving the cleanliness and vacuum performance of parts. be able to.

Claims (6)

A chemical polishing liquid for chemical polishing of alloy steel containing at least one selected from molybdenum, chromium and nickel containing hydrogen peroxide, ammonium hydrogen fluoride, phenyl glycol ethers and chloride ions. 2. The chemical polishing liquid according to claim 1 , wherein the content of hydrogen peroxide is 4 to 25 mass %. 3. The chemical polishing liquid according to claim 1, wherein the content of ammonium hydrogen fluoride is 0.5 to 10 mass %. 4. The chemical polishing liquid according to any one of claims 1 to 3 , wherein the content of phenyl glycol ether is 0.1 to 5% by mass. 5. The chemical polishing liquid according to any one of claims 1 to 4 , wherein the content of chloride ions is 0.001 to 5% by mass. A chemical polishing method for the surface of an alloy steel containing at least one selected from molybdenum, chromium and nickel , characterized in that the chemical polishing liquid according to any one of claims 1 to 5 is brought into contact with the surface of the alloy steel . chemical polishing method.

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