JP2013087336A - Method of preventing hydrogen embrittlement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent hydrogen embrittlement in iron and steel even under an environment including much hydrogen.SOLUTION: In a step S101 in a method of preventing hydrogen embrittlement, iron and steel to be treated is brought into contact with an alkaline aqueous solution. For example, an alkaline aqueous solution is stored in a predetermined container, and iron and steel is soaked in the alkaline aqueous solution. It is important that the alkaline aqueous solution has a pH at which a nonconductive coating is formed on a surface of the iron and steel brought into contact with the alkaline aqueous solution. Then, in a step S102, a potential at which hydrogen is oxidized to hydrogen ions is applied between the iron and steel and the alkaline aqueous solution.

Description

  The present invention relates to a hydrogen embrittlement prevention method for preventing hydrogen embrittlement generated in steel used for steel frames, reinforcing bars and the like.

  Steels such as high-strength steel are used as members of building elements (fixed structures) such as buildings as steel frames and reinforcing bars. It is known that this steel may become brittle due to hydrogen generated by the influence of the environment in which the structure is disposed and lose its characteristics. This embrittlement of a metal member by hydrogen is called hydrogen embrittlement, and it is assumed that a certain amount or more of hydrogen penetrates and accumulates in steel while stress is applied (non-non-uniformity). Patent Document 1).

Takao Handa, Hiroyuki Saito, Yasuhiro Higashi, Mariko Nakamura, Norihiro Fujimoto, "Delayed Fracture of Reinforced Concrete Reinforced with Hydrogen", IEICE Technical, R2009-47, pp. 7-10, 2009.

  In order to suppress the hydrogen embrittlement described above, various hydrogen embrittlement countermeasure techniques have been sought, for example, by examining the alloy composition of steel. Although certain effects have been obtained by these measures, when the amount of hydrogen in the environment where steel is used is large, hydrogen can infiltrate due to diffusion or the like, which can lead to hydrogen embrittlement. Thus, in the examination of the composition of the steel itself, since the infiltration of hydrogen cannot be suppressed, there is a problem that hydrogen embrittlement is caused in an environment where there is a lot of hydrogen.

  The present invention has been made to solve the above-described problems, and an object thereof is to suppress hydrogen embrittlement in steel even in an environment where there is a lot of hydrogen.

  The method for preventing hydrogen embrittlement according to the present invention includes at least a step of bringing steel into contact with an alkaline aqueous solution and a step of applying a potential at which hydrogen is oxidized into hydrogen ions between the steel and the alkaline aqueous solution. In addition, the alkaline aqueous solution should just be set to pH of the range in which a nonconductor film is formed on the surface of the steel which contacts.

  As described above, according to the present invention, it is possible to obtain an excellent effect that hydrogen embrittlement in steel can be suppressed even in an environment with a lot of hydrogen.

FIG. 1 is a flowchart for explaining a hydrogen embrittlement prevention method according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing a configuration example of an apparatus for realizing the hydrogen embrittlement prevention method according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart for explaining a method of preventing hydrogen embrittlement in an embodiment of the present invention.

  In this hydrogen embrittlement prevention method, first, in step S101, the target steel is brought into contact with an alkaline aqueous solution. For example, an alkaline aqueous solution may be stored in a predetermined container, and steel may be immersed in the alkaline aqueous solution. Moreover, it is good also as a state which alkaline aqueous solution contacted a part of steel. As the alkaline aqueous solution, for example, an aqueous solution of sodium hydroxide adjusted to about pH = 10 may be used. Here, in order to prevent corrosion of steel, a nonconductive film is preferably formed on the contact surface with the aqueous solution. In other words, the alkaline aqueous solution may have a pH at which a nonconductive film is formed on the surface of the steel that comes into contact.

  Next, in step S102, a potential at which hydrogen is oxidized into hydrogen ions is applied between the steel and the alkaline aqueous solution. The potential at which hydrogen becomes a hydrogen ion varies depending on the pH of the alkaline aqueous solution, but according to Nernst's theory, it may be made nobler than electrode potential E (vs. standard hydrogen electrode potential / V) = − 0.059 (pH). . Further, in practice, there is an overvoltage required for activation, so it is effective to make it nobler than the above-mentioned value.

  Next, an apparatus for realizing the above-described hydrogen embrittlement prevention method will be briefly described. As shown in FIG. 2, a potentiostat 201 is prepared, steel 202 is connected to the working electrode connection end, and a counter electrode 204 and a reference electrode 205 are arranged in an alkaline aqueous solution 203 in contact with the surface of the steel 202. . The counter electrode 204 may be a carbon electrode, for example, and the reference electrode 205 may be an Ag / AgCl electrode. The alkaline aqueous solution 203 is accommodated in the container 211, and the alkaline aqueous solution 203 accommodated in the opening 212 of the container 211 is in contact with the surface of the steel 202. By using the potentiostat 201 in this way, a potential at which hydrogen is oxidized into hydrogen ions may be applied between the steel 202 and the alkaline aqueous solution 203.

  According to the hydrogen embrittlement prevention method in the present embodiment described above, the hydrogen present in all regions in the steel diffuses toward the portion in contact with the alkaline aqueous solution. In general, hydrogen in steel at room temperature (20 to 25 ° C.) is supposed to move (diffusion) on the order of mm in about one day.

  The hydrogen that moves in this manner is released outward from the steel surface and is dissolved as ions in the alkaline aqueous solution. In addition, if hydrogen near the surface of the steel in contact with the alkaline aqueous solution is removed, the hydrogen inside the steel diffuses near the surface due to the concentration gradient, so by continuing to apply the potential other than near the interface in the steel. Existing hydrogen can also be removed. For this reason, it becomes possible to prevent hydrogen from being accumulated in steel, and hydrogen embrittlement in steel can be suppressed even in an environment where there is a lot of hydrogen.

  The treatment in the present embodiment described above is performed on a steel that has occluded hydrogen at regular intervals, and the occluded hydrogen may be removed before reaching the hydrogen occlusion amount at which hydrogen embrittlement occurs. . Further, the above-described treatment may be continuously performed to prevent hydrogen from being occluded in the steel.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious.

  DESCRIPTION OF SYMBOLS 201 ... Potentiostat, 202 ... Steel, 203 ... Alkaline aqueous solution, 204 ... Counter electrode, 205 ... Reference electrode, 211 ... Container, 212 ... Opening part.

Claims (2)

Contacting the steel with an alkaline aqueous solution;
Applying a potential at which hydrogen is oxidized into hydrogen ions between the steel and the alkaline aqueous solution. In the hydrogen embrittlement prevention method according to claim 1,
The method for preventing hydrogen embrittlement, wherein the alkaline aqueous solution has a pH within a range in which a non-conductive film is formed on the surface of the steel to be contacted.

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