JP7329473B2 - Slag remover, slag removal method, and metal material manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a slag removing agent and a slag removing method for removing slag from the surface of a metal material.

When steel materials are used to form a complicated shape, steel materials are generally joined together by welding. Welding is performed by applying heat or heat and pressure to the weld material at the joint between the steel materials to bring at least a portion of the weld material into a molten state and applying this to the joint. Here, in order to prevent entrainment of gas and generation of pores that may occur when the molten welding material solidifies in the welded part, the welding material generally contains an oxygen-removing component such as silicon or manganese. included.

Oxygen-removing components such as silicon and manganese contained in the welding material are components that prevent gaseous oxygen from being involved during solidification of the welding material by bonding with oxygen under high-temperature conditions during welding. On the other hand, these oxygen-removing components themselves combine with oxygen to form metal oxides such as silicon oxide and manganese oxide. When these metal oxides remain in the weld zone, the formation of a chemical conversion film in the subsequent chemical conversion treatment is hindered, which may result in deterioration of the corrosion resistance of the weld zone.

Japanese Patent Laying-Open No. 9-20994 (Patent Document 1) describes a method for improving corrosion resistance after coating of an arc welded portion and its vicinity. In the method described in Patent Document 1, the arc welded portion and its vicinity are treated with a non-oxidizing acid (such as hydrochloric acid) having a pH of 2 or less and a liquid temperature of 30° C. or higher and 90° C. or lower before electrodeposition coating. can be used to remove welding slag containing oxides containing Si, Mn and Fe, and to improve corrosion resistance after painting.

JP-A-9-20994

The method described in Patent Document 1 is a method using an acid solution having a pH of 2 or less as described above. On the other hand, such a strong acid solution poses a problem that sufficient consideration must be given to safety when storing the solution, when using the solution, and when treating the waste liquid after use.

The present invention is intended to solve the above-mentioned conventional problems, and its object is to provide a slag removing agent and a removal method using this slag removing agent, which can remove slag without using a strong acid solution. to provide.

In order to solve the above problems, the present invention provides the following aspects.
[1]
A slag remover that removes slag from the surface of metal materials,
The slag remover contains a chelating agent, an organic acid reducing agent, a fluorine compound and a surfactant,
The amount of fluorine atoms contained in the slag remover is within the range of 1,800 to 7,000 mass ppm,
The surfactant is at least one selected from anionic surfactants and nonionic surfactants,
The total content of the chelating agent contained in the slag remover is within the range of 3,000 to 60,000 ppm by mass.
Slag remover.
[2]
The chelating agent is at least one selected from the group consisting of phosphonic acid-based chelating agents and aminocarboxylic acid-based chelating agents.
The slag remover of [1].
[3]
The deslagging agent of [1] or [2], wherein the pH of the deslagging agent is in the range of 5-7.
[4]
The anionic surfactant is at least one selected from the group consisting of phosphate surfactants, carboxylic acid surfactants, sulfonic acid surfactants, and sulfate surfactants,
The nonionic surfactant is at least one selected from the group consisting of polyoxyalkylene glycol fatty acid esters, polyalkylene glycol fatty acid esters, and polyoxyalkylene alkyl ethers,
The total content of surfactants contained in the slag remover is in the range of 500 to 3,000 ppm by mass.
[1] to [3] Any slag remover.
[5]
The slag remover according to any one of [1] to [4], wherein the content of the organic acid reducing agent contained in the slag remover is in the range of 10,000 to 60,000 mass ppm.
[6]
further comprising a rust inhibitor,
The content of the rust inhibitor contained in the slag remover is in the range of 50 to 300 ppm by mass.
[1] to [5] Any slag remover.
[7]
A slag removal method for removing slag from the surface of a metal material, comprising the steps of:
[1] to [6] A slag removing step of contacting a metal material having slag on its surface with any of the slag removing agents to remove slag,
encompassing
Slag removal method.
[8]
A method for producing a chemically treated metal material, wherein the slag removing agent according to any one of the following steps [1] to [6] is brought into contact with the metal material having slag on the surface to remove the slag. removal process,
a chemical conversion treatment step of chemically converting the metal material from which the slag has been removed;
encompasses
The chemical conversion treatment step includes at least one selected from the group consisting of zinc phosphate chemical conversion treatment and zirconium chemical conversion treatment.
A method for manufacturing metal materials.

The slag remover of the present invention has the advantage of being able to satisfactorily remove slag from welds without using a strong acid solution by containing the above components.

The present invention relates to a slag remover for removing slag from the surface of metal materials. In this specification, slag is also referred to as welding slag, and is an oxide of these metals derived from oxygen-removing components such as silicon and manganese contained in the welding material used for molten iron of metal materials.

By the way, in removing slag from metal materials, a strong acid is generally used in many cases. For example, Patent Document 1 above discloses a method of removing slag using a non-oxidizing acid (such as hydrochloric acid) having a pH of 2 or less. On the other hand, strong acids with a pH of 2 or less, for example, pose problems in terms of work safety and the like. In the present invention, the slag formed on the surface of the metal material can be satisfactorily removed by using the remover containing the above-mentioned specific component at a specific concentration, even if the pH value is not in the strongly acidic range. Through experiments, we found that it is possible.

The deslag agents include chelating agents, organic acid reducing agents, fluorine compounds and surfactants. Each component contained in the slag remover will be described in detail below.

Chelating Agent The deslagging agent includes a chelating agent. The chelating agent is not particularly limited, and known chelating agents can be applied. By including a chelating agent in a specific content in the surface treatment agent, there is an advantage that slag can be efficiently removed from the surface of the metal material.

Examples of the chelating agent include phosphonic acid-based chelating agents and aminocarboxylic acid-based chelating agents. These chelating agents may be used singly or in combination of two or more.

Examples of the phosphonic acid-based chelating agent include HEDP, NTMP, PBTC, EDTMP and the like. Examples of aminocarboxylic acid-type chelating agents include EDTA, NTA, DTPA, HEDTA, TTHA, PDTA, DPTA-oh, HIDA, DHEG, GEDTA, CMGA, and EDDS.

The total content of chelating agents contained in the slag removing agent is within the range of 3,000 to 60,000 mass ppm. The total content is preferably within the range of 3,000 to 50,000 mass ppm. When the total content of the chelating agent is within the above range, there is an advantage that slag can be removed satisfactorily from the surface of the metal material.

Organic Acid Reducing Agent The deslagging agent includes an organic acid reducing agent. The organic acid reducing agent is not particularly limited, and known organic acid reducing agents can be applied. When the slag remover contains an organic acid reducing agent, there is an advantage that the removal of slag present on the surface of the metal material can be enhanced.

Examples of the organic acid reducing agent include:
carboxylic acid-based organic acid reducing agents such as citric acid, structural isomers of citric acid, adipic acid, ascorbic acid, erythroascorbic acid, isoascorbic acid, ascorbic acid derivatives, elsorbic acid, and gallic acid;
Polyphenolic organic acid reducing agents such as pyrogallol, catechol, hydroquinone;
Amine organic acid reducing agents such as aminohexanoic acid, hydrazine;
sulfur-based organic acid reducing agents such as cysteine and thiourea;
etc. A carboxylic acid-based organic acid reducing agent is particularly preferably used as the organic acid reducing agent.

The content of the organic acid reducing agent contained in the slag remover is preferably within the range of 5,000 to 60,000 ppm by mass, more preferably within the range of 10,000 to 60,000 ppm by mass. is more preferred. When the content of the organic acid reducing agent is within the above range, there is an advantage that the solubility of the slag present on the surface of the metal material can be improved, and the slag can be easily removed.

Fluorine compound The slag remover contains a fluorine compound. The fluorine-containing compound is not particularly limited as long as it releases fluorine ions, and known compounds can be applied. Since the slag remover contains a fluorine-containing compound that releases fluorine ions, the metal component in the slag can be stabilized in the aqueous solution, thereby efficiently removing the slag from the surface of the metal material. becomes possible.

Examples of fluorine-containing compounds that serve as fluorine ion supply sources include hydrofluoric acid, acidic sodium fluoride, acidic ammonium fluoride, fluorotitanic acid, fluorozirconic acid, fluorosilicic acid, ammonium fluoride, sodium fluoride, and fluorine. potassium difluoride, potassium hydrogen difluoride, and the like.

The content of fluorine ions contained in the slag removing agent is in the range of 1,800 to 7,000 ppm by mass in terms of fluorine atomic weight. More preferably, the content is in the range of 1,800 to 6,500 mass ppm. In the present specification, the content of fluorine ions is adjusted by adjusting the content of the fluorine-containing compound in the slag remover. When the content of fluorine ions contained in the slag remover is within the above range, there is an advantage that the metal components contained in the slag can be stabilized well in the aqueous solution.

Surfactant The deslagging agent includes a surfactant. The surfactant is at least one selected from anionic surfactants and nonionic surfactants.

The anionic surfactant is not particularly limited, and known anionic surfactants can be used. The anionic surfactant consists of a phosphate surfactant, a carboxylic acid surfactant, a sulfonic acid surfactant (including a sulfosuccinic acid surfactant), and a sulfate surfactant. It is preferably at least one selected from the group. When the slag remover contains an anionic surfactant, there is an advantage that slag can be efficiently removed from the surface of the metal material.

A commercial item can also be used as said anionic surfactant. Examples of commercially available products include DOW TRITON H66 (manufactured by Dow Chemical Japan Co., Ltd., potassium phosphate type surfactant), Neogen AS-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., sulfonic acid type surfactant), Sanmorin OT-70 (Sanyo Kasei Co., Ltd., sulfosuccinic acid surfactant), Noigen ES-99 (Daiichi Kogyo Seiyaku Co., Ltd.), Sunspearl PDN-173 (Sanyo Chemical Industries, Ltd., carboxylic acid surfactant), and the like.

Nonionic surfactants are not particularly limited, and known nonionic surfactants can be applied.

Examples of nonionic surfactants include at least one selected from the group consisting of polyoxyalkylene glycol fatty acid esters, polyalkylene glycol fatty acid esters, and polyoxyalkylene alkyl ethers. Commercially available products can also be applied, for example, Adekanol UA series (manufactured by ADEKA), Genapol EP 2564 (manufactured by Clariant Japan), Noigen XL100 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Genagen C 100 (manufactured by Clariant Japan). etc.

The surfactant content in the slag remover is preferably in the range of 500 to 3,000 ppm by mass, more preferably in the range of 500 to 2,000 ppm by mass. When the content of the surfactant is within the above range, there is an advantage that the slag can be easily removed while maintaining good workability in the slag removing operation.

Other Components The slag remover contains the above components as essential components, and may optionally contain other components within the range that does not impair the technical effects of the present invention. Such other components may include, for example, rust inhibitors. By including a rust preventive in the slag remover, there is an advantage that the rust preventiveness of the metal material can be improved after the slag is removed until the chemical conversion treatment is performed.

Rust inhibitors that can be suitably used in the slag remover include, for example, so-called P-based, N-based, S-based, and acetylene-based rust preventives. Examples of P-based rust preventives include phosphates and the like. Examples of N-based organic acid reducing agents include alkylamines, imidazoles, and triazoles. Santhiol, thiourea and the like can be mentioned as S-based rust preventives. Acetylene-based rust inhibitors include 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 2,5-dimethyl-3-hexyne-2,5-diol and 3 ,6-dimethyl-4-octyne-3,6-diol and the like. A commercial product can also be used as a rust preventive agent. Examples of commercially available products include KORANTIN PM (manufactured by BASF Japan).

When the slag remover contains a rust inhibitor, the content of the rust inhibitor is preferably 50 to 300 mass ppm. When the content of the rust preventive is within the above range, there is an advantage that the rust preventiveness of the metal material after slag removal can be enhanced.

The slag remover may contain additives that are commonly used, if necessary. Additives include, for example, pH adjusters, storage stabilizers, antifoaming agents, antifreezing agents, preservatives, antifungal agents, and the like.

Preparation of slag remover The above slag remover can be prepared by adding each of the above components to an aqueous solvent and mixing by a commonly used method. Examples of the aqueous solvent include water such as pure water, ion-exchanged water, tap water, and industrial water. The aqueous solvent may optionally contain a small amount of water-miscible organic solvent (eg, alcohols, etc.).

The pH of the deslagging agent is preferably in the range of 5-7. The above slag remover has the advantage of being able to satisfactorily remove slag from the surface of the metal material even if the pH is within the weakly acidic to neutral pH range of 5 to 7 by containing the above components. For example, if the pH of the slag remover is less than 4, the surface color of the metal material may change to black depending on the type of the metal material. In addition, when the agent is strongly acidic, the reactivity is high, so sufficient consideration must be given to safety, and the burden on the environment is also large. On the other hand, when the pH of the slag removal agent is in the range of 5 to 7, the agent is in the weakly acidic to neutral region, so it is possible to overcome the above technical problems in slag removal. There is an advantage that

Slag Removal Method In the above-described slag removal method, the metal material from which slag is removed is not particularly limited. Examples include iron materials, cold-rolled steel sheets, hot-rolled steel sheets, galvanized steel sheets, and aluminum alloy materials. In addition, if the metal material has a welded portion, it is necessary to efficiently remove the slag from the surface of the metal material, so the effect of the present invention can be particularly enjoyed.

As a slag removal method for removing slag from the surface of the metal material, a method generally used by those skilled in the art can be used. Specific slag removal methods include, for example, the following procedures.

Example 1
A slag removal method for removing slag from the surface of a metal material, comprising the steps of:
An immersion step of immersing a metal material having slag on its surface in the slag remover and bringing it into contact with the slag remover,
An ultrasonic wave application step of applying ultrasonic waves to the surface of the metal material while the metal material is immersed;
encompasses
The ultrasonic waves are irradiated within a frequency range of 25 to 100 kHz,
Slag removal method.

It is more preferable that the frequency in the above slag removal method is within the range of 30 to 50 kHz.

Example 2
A slag removal method for removing slag from the surface of a metal material, comprising the steps of:
a removing agent contact step of contacting the slag remover with a metal material having slag on its surface;
The removing agent contacting step contacts the surface of the metal material by bringing the slag removing agent into contact with the surface of the metal material at a surface flow rate of 10 to 40 cm / sec.
Slag removal method. The surface flow velocity can be measured using a commercially available surface flow meter (eg, JFE Advantech's three-axis electromagnetic flow velocity sensor ACM3-RS, etc.).

The surface flow velocity in the above slag removal method is more preferably in the range of 15-35 cm/sec.

In the removing agent contacting step, the slag removing agent is brought into contact with the surface of the metal material at a surface flow rate of 10 to 40 cm/sec. A technique of stirring is included.

Example 3
A slag removal method for removing slag from the surface of a metal material, comprising the steps of:
a removing agent contacting step of bringing the slag removing agent into contact with a metal material having slag on its surface;
encompasses
In the removing agent contact step, the slag removing agent is sprayed onto the surface of the metal material at a spray pressure of 0.08 to 2 MPa, thereby contacting the surface of the metal material.
Slag removal method.

The spray pressure in the above slag removing method is more preferably in the range of 0.1 to 1.5 MPa.

By bringing the slag remover into contact with the slag on the surface of the metal material according to the procedure such as the above example, there is an advantage that slag can be removed more favorably.

In the above method, the liquid temperature of the slag removing agent is preferably 35 to 60°C, for example. When the temperature is in the range of 35 to 60° C., the slag removing agent can be removed satisfactorily, and there is the advantage that the load on the equipment can be reduced. The temperature is preferably 40-60°C, more preferably 45-55°C.

The time for contacting the surface of the metal material with the slag remover can be appropriately selected according to each aspect. The contact time may be 30 to 600 seconds or 60 to 300 seconds in each of the above examples.

Chemical conversion treatment Chemical conversion treatment can be suitably used as a pretreatment for metal materials from which slag has been removed by the above-described slag removal method. Examples of methods for chemical conversion treatment of the metal material include zinc phosphate chemical conversion treatment and zirconium chemical conversion treatment.

Zinc phosphate chemical conversion treatment Zinc phosphate chemical conversion treatment is a chemical conversion treatment that is performed using a chemical conversion treatment agent containing zinc phosphate. The chemical conversion treatment agent containing zinc phosphate is not particularly limited, and for example, a commonly used acidic zinc phosphate chemical conversion treatment solution can be used. Preferred chemical conversion agents include 0.5 to 2 g/L of zinc ions, preferably 0.7 to 1.2 g/L, 5 to 30 g/L of phosphate ions, preferably 10 to 20 g/L of manganese ions, and 0.2 g/L of manganese ions. ~2 g/L, preferably 0.3-1.2 g/L.

The above zinc phosphating solution may optionally further contain 0.3 to 2 g/L of nickel ions, preferably 0.5 to 1.5 g/L of nickel ions, and/or 0.05 to 3 g of a fluorine compound in terms of HF. /L, preferably 0.3-1.5 g/L. The contents of zinc ions, manganese ions, nickel ions, fluoride ions, and the like in the zinc phosphating agent are measured by ICP emission spectrometry.

When the concentration of zinc ions is within the above range, there is an advantage that good corrosion resistance and paint adhesion can be obtained. When the concentration of manganese ions is within the above range, there is an advantage that better coating adhesion, corrosion resistance after coating, etc. can be ensured. In addition, the combined use of nickel ions and manganese ions has the advantage of further improving the performance of the chemical conversion film and further improving the adhesion and corrosion resistance of the coating compared to the use of manganese ions alone.

The zinc phosphating solution may contain 3 to 30 g/L of nitrate ions. However, if the content of nitrate ions exceeds 30 g/L, the phosphate film may develop scaly or yellow rust, which is not preferable.

Additionally, zinc nitrite may be included in these zinc phosphating agents. By including this, there is an advantage that film formation can be promoted. A zinc phosphating agent containing zinc nitrite and a treatment method using the same can be carried out by known methods described in, for example, JP-A-2001-323384 and JP-A-2002-212751.

The free acidity of the zinc phosphating agent is preferably 0.5 to 2.0 points. The free acidity of the treatment liquid can be determined by taking 10 ml of the treatment liquid and titrating it with 0.1N caustic soda using bromphenol blue as an indicator.

Zinc phosphate chemical conversion treatment is performed by bringing a zinc phosphate chemical conversion treatment agent into contact with a metal material. Specific examples of the method of bringing the chemical conversion treatment agent into contact with the article to be coated include an immersion method, a spray method, a roll coating method, a pouring treatment method, and the like. A general treatment temperature can be adopted as the treatment temperature in the zinc phosphate chemical conversion treatment. For example, it can be appropriately selected within the range of 20 to 70°C. The treatment time is generally 10 seconds or longer, preferably 30 seconds or longer, and more preferably 1 to 3 minutes. It is preferable that the base material subjected to the chemical conversion treatment is subjected to a spray treatment for 2 seconds or more, preferably 5 to 45 seconds, after the immersion treatment, if necessary. In order to wash off the sludge adhered during the immersion treatment by performing such a spray treatment, the spray treatment is preferably carried out for a long period of time. In the present specification, chemical conversion treatment includes not only immersion treatment but also spray treatment thereafter.

If necessary, the surface of the alloyed hot-dip galvanized steel sheet may be pretreated with a surface conditioner or the like before the chemical conversion treatment using the zinc phosphating agent. By performing this pretreatment, a zinc phosphate chemical conversion treatment layer can be satisfactorily formed on the hot-dip galvanized layer.

Zirconium Chemical Conversion Treatment Zirconium chemical conversion treatment is a chemical conversion treatment that uses a chemical conversion treatment agent containing zirconium ions. In this specification, the chemical conversion treatment agent used in the zirconium chemical conversion treatment may be referred to as "zirconium chemical conversion treatment agent".

The concentration of zirconium ions in the chemical conversion treatment agent is preferably 10 to 10000 ppm. More preferred lower and upper limits are 100 ppm and 500 ppm, respectively.

In addition, the notation of the concentration of metal ions in a chemical conversion treatment agent as a chemical conversion treatment agent in this specification is focused only on the metal atoms in the complex or oxide when a complex or oxide is formed. , and expressed in terms of metal element concentration. Therefore, the concentration of metal ions in the chemical conversion treatment agent as the chemical conversion treatment agent in this specification is the metal ion concentration when 100% dissociates and exists as metal ions, regardless of whether a part exists as nonions. Ion concentration.

Further, it contains zirconium ions and tin ions, has a zirconium ion concentration of 10 to 10000 ppm, has a concentration ratio of tin ions to zirconium ions of 0.005 to 1 in terms of mass, and has a pH of 1.5 to 6.5. may be used, or a chemical conversion treatment agent containing titanium or hafnium may be used.

Zirconium chemical conversion treatment is performed by bringing a zirconium chemical conversion treatment agent into contact with a metal material. Specific examples of the method of bringing the chemical conversion treatment agent into contact with the article to be coated include an immersion method, a spray method, a roll coating method, a pouring treatment method, and the like. Detailed conditions can be the same as those for the zinc phosphate chemical conversion treatment.

The chemically treated metal material can be suitably used, for example, for the manufacture of automobile bodies such as passenger cars, trucks, motorcycles and buses, and parts thereof.

The above slag remover can be suitably used as a remover for removing slag from the surface of a metal material. The deslagging agent can also descale in conjunction with slag. As used herein, scale means discoloration that occurs around a welded portion in welding metal materials at high temperatures.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these. In the examples, "parts" and "%" are based on mass unless otherwise specified.

Components used in Examples and Comparative Examples are shown below.
(1) Chelating agent HEDP: 1-hydroxyethane-1,1-diphosphonic acid EDTA: ethylenediaminetetraacetic acid (2) Organic acid reducing agent Citric acid Ascorbic acid (3) Fluorine compound Acidic sodium fluoride (Morita chemical company)
・ Acidic potassium fluoride (manufactured by Morita Chemical Co., Ltd.)
・ Acidic ammonium fluoride (manufactured by Morita Chemical Co., Ltd.)
(4) Surfactant Nonionic surfactant ・Adekanol UA90N (manufactured by ADEKA): polyoxyalkylene alkyl ethers anionic surfactant ・Sanmorin OT-70 (manufactured by Sanyo Kasei): sulfosuccinic acid surfactant (5) Antirust agent KORANTIN PM (manufactured by BASF Japan)

Example 1
[Preparation of metal materials]
A hot-rolled steel plate was prepared as a metal material to be processed and welded. As for the hot-rolled steel sheet, it became a metal material with slag adhering to the vicinity of the bead portion, and this was used as a test piece.

[Preparation of slag agent]
HEDP as a chelating agent, ADEKANOL UA90N (nonionic surfactant) as a surfactant, KORANTIN PM as a rust inhibitor, acidic sodium fluoride and citric acid as fluorine compounds, the content shown in Table 1 (unit: mass ppm) and adjusted to pH 6 using an aqueous KOH solution (50%) to obtain a slag remover.

[Slag removal]
The deslagging agent obtained above was placed in a 10 L treatment bath and the temperature was adjusted to 50°C. The test piece was immersed in the treatment bath, and ultrasonic waves with a frequency of 50 kHz were applied for 5 minutes using an ultrasonic device, Phoenix III (manufactured by Kaijo Co., Ltd.). After that, the test piece was taken out and thoroughly washed. After washing, drying was performed at 40° C. for about 10 minutes.

[Alkaline surface conditioning and chemical conversion treatment]
Alkaline surface conditioning was performed using Surffine 7 (manufactured by Nippon Paint Surf Chemicals Co., Ltd.) adjusted to pH 10 on the test plate from which the slag had been removed by the above procedure. The treatment temperature was room temperature and the treatment time was 30 seconds.
A zinc phosphate chemical conversion treatment was performed on the test piece subjected to the alkaline surface conditioning using Surfdyne SD5300 (manufactured by Nippon Paint Surf Chemicals Co., Ltd.), which is a zinc phosphate chemical treatment agent. The treatment temperature was 35° C. and the treatment time was 120 seconds.

[evaluation]
The metal material after removing the slag and the metal material after chemical conversion treatment were evaluated as follows. Table 1 shows the evaluation results.

(slag removal)
The slag removability was evaluated by visually judging the slag residual rate of the test piece after slag removal.

(Measurement of silicon reduction amount by fluorescent X-ray analysis)
The amount of silicon adhering to the surface of the sample piece before slag removal was measured using an energy dispersive X-ray spectrometer, JSM6510A (manufactured by JEOL Ltd.).
The amount of silicon adhering to the surface of the test piece after slag removal was similarly measured.
The amount of silicon reduction was determined by the following formula.

Amount of silicon reduction (%) = (Amount of silicon before removal - Amount of silicon after removal) / (Amount of silicon before removal)

(Evaluation of chemical conversion film coverage)
The surface of the test piece (weld portion) after zinc phosphate chemical conversion treatment was observed using a scanning electron microscope JSM6510A (manufactured by JEOL Ltd.), and the coverage (%) of the chemical conversion film formed on the surface of the test piece was evaluated. did.

(Rust generation evaluation)
After washing the test piece after treatment with the slag remover, it was allowed to stand while still wet at room temperature, and the amount of rust generated after 5 minutes was evaluated according to the following criteria.

Yes: Rust generation was confirmed No: Rust generation was not confirmed

Examples 2-6, Comparative Examples 1-2
In the preparation of the slag remover, slag removal treatment and chemical conversion treatment were performed and evaluated in the same manner as in Example 1, except that the amount of each component was changed as shown in the table below. The evaluation results are shown in the table below.

It was confirmed that the slag was removed satisfactorily in all of the above examples.
Comparative Example 1 is an example in which the amount of chelating agent is less than the range of the present invention. In this example, it was confirmed that the amount of residual slag was large and the slag removal was not sufficient.
Comparative Example 2 is an example in which the content of the fluorine compound is below the scope of the present invention. In this example, it was confirmed that the amount of residual slag was slightly large and the slag removal was not sufficient, and that the amount of silicon decreased was small and the amount of residual silicon was large.

By using the above-described slag remover, the slag of the weld zone can be preferably removed from the surface of the metal material without using a strong acid solution.

Claims (6)

A slag remover that removes welding slag from the surface of metal materials,
The slag remover comprises a chelating agent, an organic acid reducing agent, a fluorine compound and a surfactant,
The amount of fluorine atoms contained in the slag remover is within the range of 1,800 to 7,000 mass ppm,
The surfactant is at least one selected from anionic surfactants and nonionic surfactants,
The total content of the chelating agent contained in the slag remover is within the range of 3,000 to 60,000 mass ppm,
The pH of the deslagging agent is in the range of 5 to 7,
The chelating agent is at least one selected from the group consisting of phosphonic acid-based chelating agents and aminocarboxylic acid-based chelating agents,
The organic acid reducing agent is a carboxylic acid-based organic acid reducing agent, a polyhydric phenol organic acid reducing agent, or a sulfur-based organic acid reducing agent,
The total content of the chelating agent and the organic acid reducing agent is 53,000 to 100,000 ppm by mass .
Slag remover. The anionic surfactant is at least one selected from the group consisting of phosphate surfactants, carboxylic acid surfactants, sulfonic acid surfactants, and sulfate surfactants,
The nonionic surfactant is at least one selected from the group consisting of polyoxyalkylene glycol fatty acid esters, polyalkylene glycol fatty acid esters, and polyoxyalkylene alkyl ethers,
The total content of surfactants contained in the slag remover is in the range of 500 to 3,000 ppm by mass.
The slag remover according to claim 1 . The slag remover according to claim 1 or 2 , wherein the content of the organic acid reducing agent contained in the slag remover is within the range of 10,000 to 60,000 mass ppm. further comprising a rust inhibitor,
The content of the rust inhibitor contained in the slag remover is in the range of 50 to 300 ppm by mass.
The slag remover according to any one of claims 1 to 3 . A slag removal method for removing welding slag from the surface of a metal material, comprising the steps of:
A slag removing step of bringing the slag remover according to any one of claims 1 to 4 into contact with a metal material having welding slag on its surface to remove the welding slag,
encompassing
Slag removal method. A method for producing a chemically treated metal material, comprising: contacting a metal material having welding slag on its surface with the slag remover according to any one of the following steps to remove the welding slag. , slag removal process,
a chemical conversion treatment step of chemically converting the metal material from which the welding slag has been removed;
encompasses
The chemical conversion treatment step includes at least one selected from the group consisting of zinc phosphate chemical conversion treatment and zirconium chemical conversion treatment.
A method for manufacturing metal materials.