JP2001152373A - Iron rust stabilizer, method for forming stabilized iron rust layer and steel material having stabilized iron rust layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an iron rust stabilizer forming a stabilized iron rust layer excellent in the properties of cutting off from the outside on the surface of a steel material, to provide a method for forming the same layer and to produce a steel material having the same layer. SOLUTION: The iron rust stabilizer in this invention is composed of an aqueous solution containing one or two or more kinds among the ions of a metallic element A and/or a metallic element B satisfying the conditions in the following inequalities (1) and (2) in the case the hydrolysis constant of the metallic ions of some metallic element M is defined as K (M) as essential components respectively by >=0.001 M/l, preferably by >=0.005 M/l in total. By applying this iron rust stabilizer on a steel material, a refined and densified stabilized iron rust layer is formed, and the corrosion resistance of the steel material improves: K(Fe3+)-3.5<K(A)<K(Fe3+)+2.5...(1), and K(Fe2+)-3.5<K (B)<K(Fe2+)+2.5...(2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a stabilized iron rust layer having a protective property in an atmospheric corrosion environment on a steel structure such as a bridge or a building. , Rust layer and coating film).

[0002]

2. Description of the Related Art Weather-resistant steel used for bridges and buildings is known as a steel material that transfers steel with iron rust generated on its surface, and JIS describes weather-resistant hot-rolled steel (SM) for welded structures.
A: JISG3114) and high weather resistant rolled steel (SPA:
JISG3125). Weather-resistant steel can be used naked without coating, and it is economical.However, the surface rust is generated until the iron rust on the surface becomes dense and stable and good rust. There are many problems.

[0003] Further, under a chloride environment in which snowmelt is sprayed in a coastal area or in winter, a layered iron rust which easily peels off (exfoliation rust: for example, it is considered that β rust composed of coarse particles is contained) is generated. However, dense and stable iron rust having excellent corrosion resistance is not formed.

As a method of compensating for these disadvantages, for example,
Japanese Patent Publication No. 56-33991 describes a technique for improving corrosion resistance by forming a chemical conversion film, and Japanese Patent No. 2699733 discloses a technique for improving the corrosion resistance by 1.0 to 45.0 wt%.
A technique is described in which a stabilized iron rust layer is formed by applying a chromium sulfate aqueous solution as a coating liquid to the surface of a steel material or a rust layer of the steel material, thereby improving corrosion resistance.

[0005]

However, the conventional chemical conversion coating treatment requires complicated pre-treatment and cannot provide an iron rust layer having good corrosion resistance even if it is complicated. In a chloride environment such as a zone, exfoliation rust is easily generated, and thus satisfactory corrosion resistance is not necessarily obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to form a stabilizing iron rust layer having an excellent barrier property against the outside on a surface of a steel material, thereby improving the corrosion resistance of the steel material. It is an object to provide an agent, a method for forming a stabilized iron rust layer, and a steel material having a stabilized iron rust layer.

[0007]

There are still many unknown points in the process of forming iron rust.
It is said that e ³⁺ ions or Fe ²⁺ ions ^originate and crystallize through hydrolysis, polymerization, nucleation growth, aggregation, condensation, etc., and precipitate as rust. If the growth of rust can be suppressed at the stage of this hydrolysis, the rust particles will not grow, and will be miniaturized and densified, and the barrier property to the outside will be improved. The present invention has been completed based on such an idea. Iron rust includes β rust, α rust, γ rust, magnetite, and amorphous rust, and α rust and amorphous rust are originally preferable from the viewpoint of corrosion resistance.

That is, the iron rust stabilizer of the present invention is an iron rust stabilizer which forms a stabilized iron rust layer on the surface of a steel material by being supplied on the steel material as described in claim 1. When the hydrolysis constant of a metal ion of a certain metal element M is represented by K (M), one or more kinds of ions of the metal element A satisfying the condition of the following formula (1) are essential components. And the total amount is 0.001M /
1 or more. K (Fe ³⁺ ) −3.5 <K (A) <K (Fe ³⁺ ) +2.5 (1) where the hydrolysis constant K (M) is obtained by the following equation.
When represented by (A), it is a value determined by the following equation (B). _{^{xM z + + yH 2 O =}} M x (OH) y (xz-y) + + yH + ...... (A) K (M) = log Q xy = log [M x (OH) y (xz-y) +] [ H ⁺ ] ^y / [ ^{Mz +} ] ^x ... (B)

When the steel material is corroded to form rust from Fe ³⁺ ions, ions of the metal element A having a hydrolysis constant satisfying the condition of the formula (1) (may be simply referred to as A ions). If present, A ions are adsorbed on rust nuclei or particle surfaces or taken into rust, thereby affecting rust formation and suppressing growth. As a result, nucleation, grain growth, and crystallization of rust are prevented, and the generated rust becomes finer and denser, and stabilization functions as a protective layer that can prevent the intrusion of corrosion factors such as chlorine ions and moisture from the outside. The iron rust layer can be formed on the surface of the steel material, and the corrosion resistance of the steel material can be improved.

At this time, the hydrolysis constant is (K (Fe ³⁺ ) −
If it is smaller than 3.5), Fe ³⁺ ions are formed and precipitated first as rust, so that the crystal size of the formed rust is not affected. On the other hand, if it is larger than (K (Fe ³⁺ ) +2.5), A ³ is generated before Fe ³⁺ ions are formed as rust and precipitate.
The ions precipitate first and do not affect rust. That is, even if the hydrolysis constant is too large or too small, it cannot affect the generation and growth of rust generated from Fe ³⁺ ions. Therefore, in order to make rust finer and more dense, the hydrolysis constant is (K (Fe ³⁺ ) -3.5).
It is necessary to select an A ion satisfying the condition of <K (A) <(K (Fe ³⁺ ) +2.5) as an additive.
Examples of the metal element A having such a hydrolysis constant K (A) include, for example, Z
r, Hf, Ti, Ga, Sn, Al, Cr, Sc, I
An element selected from n, Bi, and V can be used.

The concentration of A ions in the aqueous solution constituting the iron rust stabilizer (total amount of various A ions) is as follows.
At least 0.001 M / l (mole / liter) is required to obtain the rust refining effect of the ions. Therefore, the lower limit of the concentration of the A ion is 0.001 M / l, preferably 0.005 M / l. And The upper limit of the concentration of the A ion is not particularly defined, and may be a saturated aqueous solution of the A ion. However, even if it is contained in an excessive amount, the micronizing action is saturated and is not economical. It is better to stop at about l.

Further, the iron rust stabilizer of the present invention is an iron rust stabilizer which forms a stabilized iron rust layer on the surface of a steel material by being supplied on the steel material. When the hydrolysis constant of a metal ion of a certain metal element M is expressed as K (M), one or more of the ions of the metal element B satisfying the condition of the following formula (2) are essential components. And an aqueous solution having a total amount of 0.001 M / l or more. However, the hydrolysis constant K (M) is a value determined by the above formula (B) when the hydrolysis reaction is represented by the above formula (A). K (Fe ²⁺ ) −3.5 <K (B) <K (Fe ²⁺ ) +2.5 (2)

The present invention has been made by paying attention to rust generated from Fe ²⁺ ions.
When rust is formed from the e ²⁺ ion, if there is an ion of the metal element B having a hydrolysis constant that satisfies the condition of the formula (2) (may be simply referred to as B ion), the Fe ³⁺ is used.
By the same mechanism as the miniaturization and densification of rust generated from ions, the growth of rust particles generated from Fe ²⁺ ions can be suppressed and miniaturized, and stabilized iron rust with excellent barrier properties to the outside Layers can be formed.

At this time, the hydrolysis constant is (K (Fe ²⁺ ) −
When it is smaller than 3.5), the Fe ²⁺ ion is first generated and precipitated as rust, so that it does not affect the crystal grain size of the rust generated from the Fe ²⁺ ion. On the other hand, (K (Fe ²⁺ )
If it is larger than (+2.5), B ions are precipitated first before Fe ²⁺ ions are generated and precipitated as rust, and the rust crystal grain size is not affected. For this reason, in order to make rust finer and more dense, the hydrolysis constant is (K
(Fe2 ⁺ )-3.5) <K (B) <(K (Fe2 ⁺ ) +
It is necessary to select a B ion satisfying the condition of 2.5) as an additive. Such a hydrolysis constant K
Examples of the metal element B having (B) include, for example, Ca, Ag, Mg, Mn, N
An element selected from i, Co, La, Zn, Pb, and Cu can be used. In addition, the concentration of B ions in the aqueous solution constituting the iron rust stabilizer (total amount of various B ions) is at least 0.
001 M / l is required, preferably 0.005 M / l
It is better to be 1 or more. The upper limit of the B ion concentration is not particularly limited, but is preferably about 10 M / l from the viewpoint of economy.

Further, the iron rust stabilizer of the present invention contains, as an essential component, one or more of the ions of the metal element A described in the first aspect as an essential component,
The total amount is 0.001 M / l or more, and one or more of the ions of the metal element B according to claim 3 is contained as an essential component, and the total amount is 0.001 M / l.
/ L or more of an aqueous solution. According to the present invention, all rusts generated from Fe ²⁺ ions and Fe ³⁺ ions can be miniaturized and densified, whereby stabilized iron rust functioning as a protective film having an excellent barrier to corrosion factors The layer can be formed on the surface of the steel material, and the corrosion resistance of the steel material can be further improved.

As described in claim 7, the aqueous solution constituting the iron rust stabilizer of each of the above-mentioned inventions further contains sulfate ions (SO ₄ ²⁻ ) as an essential component in an amount of 0.01 to 10 M / min.
It is better to include l. Sulfate ions have the effect of promoting thermodynamically stable alpha rust. When the amount is less than 0.01 M / l, such an effect is too small. On the other hand, when the amount exceeds 10 M / l, the effect is saturated and handling becomes difficult.

Further, the method for forming a stabilized iron rust layer according to the present invention is characterized in that, as set forth in claim 8, the method comprises the steps of:
(7) The iron rust stabilizer described in any one of (7) to (7) is supplied to form a stabilized iron rust layer containing the metal element A and / or the metal element B on the surface of the steel material. According to the present invention, by the action of the iron rust stabilizing agent, the generated rust can be miniaturized and densified, and the stabilized iron rust layer can be easily formed as a protective layer having excellent barrier properties on the surface of the steel material. be able to.

Further, the steel material having a stabilized iron rust layer according to the present invention is characterized in that, as described in claim 9, the iron rust stabilizer described in any one of claims 1 to 7 is provided on the steel material. It is supplied, and a stabilized iron rust layer containing the metal element A and / or the metal element B is formed on the surface of the steel material.
This stabilized iron rust layer is formed by the above-mentioned iron rust stabilizing agent, and the rust formed therein is refined and densified, and functions as a protective layer having excellent barrier properties on the surface of the steel material, thereby improving the corrosion resistance of the steel material. Can be done. As the steel material, a material containing at least one of Ti: 0.01% or more, Cu: 0.1% or more, and Ni: 0.1% or more in wt% is preferable. From the steel itself, Ti as the metal element A
And Cu and Ni as the metal element B can be supplied, which can promote the miniaturization and densification of the generated rust, which is effective.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies on the corrosion mechanism of metal materials and the process of forming rust, and have found that there is a correlation between corrosion resistance and the type and structure of rust. That is,
The smaller the amount of β rust (β-FeOOH) that is easily formed in a chloride environment in the iron rust layer and that is fragile and easy to peel off, the more thermodynamically stable α rust (α-FeOOH) and amorphous rust The higher the number, the better the corrosion resistance. However, even with the same type of rust, a finding was found that the smaller the particle size, the more excellent the corrosion resistance. In other words, fine and dense rust with excellent corrosion resistance is obtained by refining coarse β rust, which is easy to generate in a chloride environment, brittle and easy to peel, and further refining α rust, which has a good effect on corrosion resistance. Layers can be formed. Then, during the production process of iron rust, a factor (hydrolysis constant) that determines the growth rate and particle size of rust was found, and the present invention was completed. It should be noted that very fine β rust is difficult to distinguish from amorphous rust, but since amorphous rust originally contributes to the improvement of corrosion resistance, there is no practical benefit of strictly distinguishing the two. Also,
Alpha rust is a thermodynamically stable rust by nature and is suitable for imparting corrosion resistance. According to the present invention, the α rust is also miniaturized and densified, so that the barrier property to the outside is further improved.

First, the hydrolysis constant will be described in detail. The hydrolysis is an acid-base reaction in which a metal ion and water react to break an OH bond to give a hydroxide (ion) and a proton H ⁺ . For example, if the m-valent metal ion M ^{m +} is a strong acid and M (OH) ^{(m-1) +} is its conjugate weak base,
The acid-base reaction is given by the following equation. M ^{m +} + H ₂ O = M (OH) ^{(m-1) +} + H ^{+ In} general, the hydrolysis reaction is reversible, and this equilibrium constant is called the hydrolysis constant. The hydrolysis constant K (M) of a metal ion of a certain metal element M is a value obtained by the following equation (B) when the hydrolysis reaction is represented by the following equation (A). _{^{xM z + + yH 2 O =}} M x (OH) y (xz-Y) + + yH + ...... (A) K (M) = log Q xy = log [M x (OH) y (xz-y) +] [ H ⁺ ] ^y / [ ^{Mz +} ] ^x ... (B)

Rust generated based on Fe ³⁺ ions,
For example, in order to achieve finer and more dense β rust that is likely to be generated in a chloride environment, the following equation (1) is used using the above hydrolysis constant.
Contains, as an essential component, one or more ions of the metal element A specified in the above, and the total amount thereof is 0.001 M / l
As described above, it can be achieved by supplying an iron rust stabilizer composed of an aqueous solution of preferably 0.005 M / l or more to a steel material. K (Fe ³⁺ ) −3.5 <K (A) <K (Fe ³⁺ ) +2.5 (1)

The metal element A has a hydrolysis constant of K (F
e.sup.3 ⁺ ) has a remarkable rust refining and densification action. Therefore, the metal element A is preferably K (Fe3 ⁺ )-1.5 <K (A) <K (Fe3 ⁺ ). ) +1.5 (1A) is preferable.

Hydrolysis constant of Fe ³⁺ ion K (Fe ³⁺ )
Is a general value at room temperature of -2.4 ("Hydrolysis of Ca
tions ": Charles F. Jr. Baes, Robert E. Mesmer, Kriege
r Publishing Company, 1986, p230), equation (1) is -5.9 <K (A) <0.1, and equation (1A) is -3.9 <K (A) <-0.9 It is expressed as

There are many metal elements A having a hydrolysis constant in the range of -5.9 to 0.1, but Zr (hydrolysis constant K = -0.6) ,
Hf (K = -1.1), Ti (K = -2.3), Ga
(K = −2.6), Sn (K = −3.4), Al (K =
-5.0), Cr (K = -3.9), Sc (K = -4.
3), In (K = -4.0), Bi (K = -1.1),
V (K = −3.3) is preferably selected. Of course, you may select from arbitrary element groups among these elements. For example, it can be selected from Ga, Sn, Al, Cr, Sc, In, and Bi. Zr, Hf, Ti, Cr,
V may be selected. In addition, as these elements used as iron rust stabilizers, these elements correspond to various stages in the process of rust formation, and therefore, it is better to contain two or more than one kind (Zr, Hf, Ti, One or more of (Cr, V) and (Ga, Sn, Al, Cr, Sc, I
n, Bi) or one or more elements from Ti and (Ga, Sn, Al, Cr, Sc, In, Bi).
It is effective to use a combination of two or more elements.

On the other hand, in order to miniaturize and densify rust, which is considered to be generated based on Fe ²⁺ ions, the metal element B specified by the following formula (2) using the above hydrolysis constant is used. An iron rust stabilizer consisting of an aqueous solution containing one or more of the following ions as essential components and having a total amount of 0.001 M / l or more, preferably 0.005 M / l or more, is supplied to the steel material. Can be achieved by: K (Fe ²⁺ ) −3.5 <K (B) <K (Fe ²⁺ ) +2.5 (2)

The metal element B also has a hydrolysis constant of K (F
e.sup.2 ⁺ ), the effect of refining and densification of rust is remarkable. Therefore, the metal element B is preferably K (Fe3 ⁺ )-1.5 <K (A) <K (Fe3 ⁺ ). ) +1.5 It is preferable to satisfy (2A).

The Fe ²⁺ hydrolysis constant K (Fe ²⁺⁾ is as a general value at room temperature -9.5 ( "Hydrolysis of Cati
ons ", supra), Equation (2) is -13 <K (B) <
−7.0, Equation (2A) is expressed as −11 <K (A) <− 8.

Although there are many elements having a hydrolysis constant in the range of -13 to -7.0, Ca (hydrolysis constant K = -13.0), Ag
(K = -12.0), Mg (K = -11.4), Mn
(K = -10.6), Ni (K = -9.9), Co (K
= -9.7), La (K = -9.0), Zn (K =-
9.0), Pb (K = -7.7), Cu (K = -8.
It is better to select 0). Of course, you may select from arbitrary element groups among these elements. For example, Ag, M
g, Mn, Ni, Co, La, Zn, and Pb. Moreover, you may select from Ca, Ni, and Cu. Also, as an element used as an iron rust stabilizer,
Since these elements correspond to various steps in the process of rust formation, it is better to contain two or more than one.
In particular, one or more of (Ca, Ni, Cu) and (Ag,
It is effective to use a combination of at least one element from Mg, Mn, Co, La, Zn, and Pb).

The iron rust stabilizer of the present invention can be constituted by an aqueous solution containing a predetermined amount of the ion of the metal element A and / or the metal element B as an essential component. By making both ions an essential component, all rusts generated from Fe ²⁺ ions and Fe ³⁺ ions, that is, β rust, α rust, γ rust, magnetite and amorphous rust are all refined and dense. And a rust layer having a very good barrier property can be formed. However, metal element A
And / or the ions of the metal element B are essential components, and in the aqueous solution of the iron rust stabilizer, in addition to the above-mentioned ions, components that do not hinder the rust refining and densification by these ions, or improve such effects. Components that cause the

For example, 0.01 to 10 M / l of a sulfate ion (SO ₄ ²⁻ ) having a function to make α rust redundant can be contained. The aqueous solution is desirably acidic to some extent from the viewpoint that the surface of the steel material to which the iron rust stabilizing agent is applied corrodes a new rust layer earlier. By containing sulfate ions, such an effect can also be obtained. Note that Ti is used as the metal element A.
Is used as an essential component, and in order to simultaneously contain sulfate ions, titanium sulfate may be dissolved in water.

Further, in order to uniformly supply the iron rust stabilizer to the surface of the steel material on which the stabilized iron rust layer is formed,
It is desirable to reduce the surface tension of the aqueous solution of iron rust stabilizer. From this viewpoint, it is effective to mix a water-soluble solvent having a lower surface tension than water at normal temperature. As such a solvent, for example, lower alcohols such as ethanol and methanol and acetone can be exemplified from the viewpoint of economy, safety, handleability, and the like. About the mixing amount,
It is preferable to contain about 0.1 M / l or more.

The method of supplying the iron rust stabilizer to the steel material is arbitrary. The iron rust stabilizer may be sprayed or brushed on the surface of the steel material, and may be applied to the steel material. The material may be immersed. Spraying is preferable in consideration of economy and workability. The coating may be performed after the iron rust stabilizer is supplied to the steel material and dried.

The iron rust stabilizer of the present invention is effective for any steel material as long as it forms iron rust, including weathering steel. In particular, as a steel component, Ti: 0.01% or more (preferably 0.03% by weight)
%), Cu: 0.1% or more (preferably 0.3% or more), Ni: 0.1% or more (preferably 0.3% or more)
A steel material containing at least one of the above can effectively supply ions of these elements from the steel material itself as long as the generation of iron rust progresses, which is effective in improving corrosion resistance.
Further, a coating film or a rust layer may be formed on the surface of the steel material. That is, the present invention can be effectively used in repairing steel and rust that have already been corroded, repairing a defective portion of the coating film, and the like.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not construed as being limited to such Examples.

[0035]

EXAMPLES Iron rust stabilizers comprising aqueous solutions containing various components shown in Tables 1 and 2 below were prepared. The metal element means its ion, and the sulfate ion (SO ₄ ^2- ) is obtained by dissolving titanium sulfate in water. The following chemical composition (unit wt%, balance substantially Fe):
Was sprayed on the surface of ordinary steel sheet and low alloy steel sheet, dried, and then subjected to an accelerated atmospheric exposure test in an industrial area. Exposure test was 15
A test specimen having a size of 0 × 70 × 6 mm in thickness was leaned to the south at an angle of 45 °, and 0.1% NaCl aqueous solution was sprayed once a week to promote corrosion. After 12 months of exposure, appearance evaluation and corrosion were performed. A weight loss survey is conducted. -Common steel component C: 0.09%, Si: 0.35%, Mn: 1.45
%, P: 0.015%, S: 0.015%, Cu: 0.
01%, Ni: 0.01%, Al: 0.02% Low alloy steel component C: 0.07%, Si: 0.34%, Mn: 1.50
%, P: 0.012%, S: 0.013%, Cu: 0.
51%, Ni: 0.50%, Al: 0.02%, Ti:
0.05%

The appearance of the exposure test was evaluated according to the following criteria, and was evaluated on a five-point scale from ◎ to ×. The corrosion rate was determined from the weight before and after the test to determine the corrosion weight loss, and was calculated as a ratio to the weight loss of the ordinary steel sheet (untreated material, No. 1 in Table 1) not coated with the iron rust stabilizer.・ Appearance evaluation criteria ◎◎: Peeling rust and flow rust are 0 to 10% in area ◎ ： Peeling rust and flow rust are 11 to 20% in area ○: Peeling rust and flow rust are 21 to 30% in area Δ: Peeling rust and flow rust are 31% and 50% in area ×: Peeling rust and flow rust are 51% or more in area

[0037]

[Table 1]

[0038]

[Table 2]

From Tables 1 and 2, it can be seen that the steel sheet coated with the iron rust stabilizer of the present invention (Sample Nos. 2 to 37: Inventive Example) had better appearance evaluation and corrosion than the untreated steel sheet (Sample No. 1). Excellent in both weight loss. In addition, it can be seen that the iron rust stabilizing agent containing more metal ions having an action of miniaturizing and densifying iron rust, and containing sulfuric acid ions, ethanol, etc., are more excellent in corrosion resistance. Further, as a steel material to which the iron rust stabilizer is applied, a low alloy steel sheet containing an effective element such as Ti has a lower corrosion loss and is more excellent in corrosion resistance.

[0040]

According to the present invention, as an essential component of the iron rust stabilizer, one or two or more kinds of metal element ions close to the hydrolysis constant of Fe ion which is a source of iron rust are essential components. By supplying iron rust stabilizing material to steel, β rust, α rust, γ rust, etc. formed on the surface can be refined and densified, and the surface of steel In addition, a stabilized iron rust layer having an excellent barrier property to the outside is formed, thereby improving the corrosion resistance of the steel material.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Suga 1 Kanazawa-cho, Kakogawa-shi, Hyogo Prefecture Inside Kobe Steel Works Kakogawa Works (72) Inventor Satoshi Takeshita 1 Kanazawa-cho, Kakogawa-shi, Hyogo Kobe Corporation 4K062 AA01 BA05 BA08 CA05 CA10 FA16 GA01 GA10

Claims (10)

[Claims] An iron rust stabilizing agent for forming a stabilizing iron rust layer on the surface of a steel material by supplying the iron rust layer on the steel material, wherein a hydrolysis constant of a metal ion of a certain metal element M is represented by K (M )
When the metal element A satisfies the condition of the following formula (1),
An iron rust stabilizer comprising an aqueous solution containing one or more of the following ions as essential components and having a total amount of 0.001 M / l or more. K (Fe ³⁺ ) −3.5 <K (A) <K (Fe ³⁺ ) +2.5 (1) where the hydrolysis constant K (M) is obtained by the following equation.
When represented by (A), it is a value determined by the following equation (B). _{^{xM z + + yH 2 O =}} M x (OH) y (xz-y) + + yH + ...... (A) K (M) = log Q xy = log [M x (OH) y (xz-y) +] [ H ⁺ ] ^y / [ ^{Mz +} ] ^x ... (B) 2. The metal element A is Zr, Hf, Ti, G
The iron rust stabilizer according to claim 1, which is an element selected from a, Sn, Al, Cr, Sc, In, Bi, and V. 3. An iron rust stabilizing agent which forms a stabilized iron rust layer on the surface of a steel material by being supplied on the steel material, wherein the metal ion of a certain metal element M has a hydrolysis constant of K (M )
When the metal element B satisfies the condition of the following formula (2),
An iron rust stabilizer comprising an aqueous solution containing one or more of the following ions as essential components and having a total amount of 0.001 M / l or more. K (Fe ²⁺ ) −3.5 <K (B) <K (Fe ²⁺ ) +2.5 (2) where the hydrolysis constant K (M) is obtained by the following equation.
When represented by (A), it is a value determined by the following equation (B). _{^{xM z + + yH 2 O =}} M x (OH) y (xz-y) + + yH + ...... (A) K (M) = log Q xy = log [M x (OH) y (xz-y) +] [ H ⁺ ] ^y / [ ^{Mz +} ] ^x ... (B) 4. The metal element B includes Ca, Ag, Mg, M
The iron rust stabilizer according to claim 3, which is an element selected from n, Ni, Co, La, Zn, Pb, and Cu. 5. The method according to claim 3, wherein one or more of the ions of the metal element A described in claim 1 is contained as an essential component, and the total amount is 0.001 M / l or more. An iron rust stabilizer comprising an aqueous solution containing one or more ions of the metal element B as an essential component and having a total amount of 0.001 M / l or more. 6. The iron rust stabilizer according to claim 5, wherein the metal element A is selected from the elements described in claim 2, and the metal element B is selected from the elements described in claim 4. 7. The method according to claim 1, further comprising 0.01 to 10 M / l of sulfate ion as an essential component.
The iron rust stabilizer described in the section. 8. The method according to claim 1, wherein the steel material is provided on a steel material.
A method for forming a stabilized iron rust layer, comprising supplying the iron rust stabilizing agent described in the above section and forming a stabilized iron rust layer containing the metal element A and / or the metal element B on the surface of the steel material. 9. The method according to claim 1, wherein the steel material is provided on a steel material.
A steel material having a stabilized iron rust layer, wherein the iron rust stabilizing agent described in the paragraph is supplied, and a stabilized iron rust layer containing a metal element A and / or a metal element B is formed on a surface of the steel material. 10. The stable material according to claim 9, wherein the steel material contains at least one of Ti: 0.01% or more, Cu: 0.1% or more, and Ni: 0.1% or more in wt%. A steel material with an iron rust layer.