JP2002221483A - Testing liquid and method for evaluating corrosion resistance of stainless steel - Google Patents
Testing liquid and method for evaluating corrosion resistance of stainless steelInfo
- Publication number
- JP2002221483A JP2002221483A JP2001017358A JP2001017358A JP2002221483A JP 2002221483 A JP2002221483 A JP 2002221483A JP 2001017358 A JP2001017358 A JP 2001017358A JP 2001017358 A JP2001017358 A JP 2001017358A JP 2002221483 A JP2002221483 A JP 2002221483A
- Authority
- JP
- Japan
- Prior art keywords
- stainless steel
- corrosion resistance
- potential
- evaluating
- hydrogen peroxide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、河川ダム、河口
堰、農業用水路、水道管あるいは地下水や工業用水を用
いた化学プラントでの静水圧試験、循環冷却水、海水貯
蔵用タンク類、海水輸送用ラインパイプ類など、淡水、
汽水あるいは海水など複合的な環境微生物が存在する自
然水環境で使用されるステンレス鋼に対して耐食性を評
価するために用いる試験液およびその使用方法に関す
る。The present invention relates to hydrostatic pressure tests in river dams, estuaries, agricultural waterways, water pipes or chemical plants using groundwater or industrial water, circulating cooling water, tanks for storing seawater, seawater transportation, etc. Fresh water, such as line pipes for
The present invention relates to a test solution used for evaluating corrosion resistance of stainless steel used in a natural water environment where complex environmental microorganisms such as brackish water or seawater exist, and a method of using the same.
【０００２】[0002]
【従来の技術】河川ダム、河口堰、農業用水路、水道管
あるいは地下水や工業用水を用いた化学プラントでの静
水圧試験、循環冷却水、海水貯蔵用タンク類、海水輸送
用ラインパイプ類など、淡水、汽水、あるいは海水など
の環境微生物が存在する水環境でステンレス鋼使用を検
討する場合、これまで環境中の微生物作用に起因する腐
食発生については、重要視されてこなかった。しかしな
がら、近年、環境微生物による腐食誘起作用が無視でき
ないものであることが、明らかになりつつある。特に、
酸素が利用できる好気環境中では、微生物の作用によっ
てステンレス鋼の浸漬電位が貴化する現象が知られてお
り、ステンレス鋼に腐食を誘起する主要因と考えられ
る。好気性微生物作用による電位貴化は、浸漬される淡
水、汽水あるいは海水の季節変動によって、到達する貴
化電位が変動する。電位レベルが高くなるほど、ステン
レス鋼にすきま腐食あるいは孔食が発生する可能性が高
くなる。ステンレス鋼のすきま腐食あるいは孔食の発生
は浸漬電位と密接な関係にある。浸漬電位が貴化して、
すきま腐食発生の臨界電位であるすきま腐食再不働態化
電位を超えるとすきま腐食を発生する可能性がある。ま
た、浸漬電位が貴化して孔食電位を超えると孔食が生じ
る（辻川茂男、久松敬広：防食技術、２９、３７（１９
８０））。すきま腐食の方が孔食よりもはるかに発生し
やすく、孔食電位はすきま腐食再不働態化電位よりも高
い値となる。ステンレス鋼の実使用では溶接部やねじ止
めなど、構造上、すきま構造を避けることは極めて難し
い。電位貴化は、すきま構造に対して、腐食の発生原因
となると共に、不働態被膜の再不働態化を阻害する原因
にもなる。したがって、河川水や海水などでは微生物作
用による電位貴化の影響を考慮した条件で、すきま腐食
に対するステンレス鋼の耐食性を評価する必要がある。
微生物腐食に対するステンレス鋼の耐食性を評価する従
来技術としては、培養微生物を用いる方法（特開平１１
−２９９４９７号公報）や酸化酵素を用いた方法（特開
平６−７８７９４号公報、特開平８−６８７７４号公
報）、微生物腐食を考慮した腐食試験装置（特開平５−
２６４４９７号公報）などがある。また、微生物腐食と
は異なるが、酸化剤による電位貴化作用によってステン
レス鋼の耐すきま腐食性を評価する方法として、6% 塩
化第二鉄溶液浸漬試験法（ASTM G48）がある。2. Description of the Related Art Hydrostatic pressure tests at river dams, estuaries, agricultural waterways, water pipes or chemical plants using groundwater or industrial water, circulating cooling water, tanks for storing seawater, line pipes for transporting seawater, etc. When considering the use of stainless steel in an aqueous environment where there are environmental microorganisms such as freshwater, brackish water, or seawater, the occurrence of corrosion caused by the action of microorganisms in the environment has not been regarded as important. However, in recent years, it has been becoming clear that the corrosion-inducing action by environmental microorganisms cannot be ignored. In particular,
In an aerobic environment where oxygen can be used, it is known that the immersion potential of stainless steel becomes noble due to the action of microorganisms, and this is considered to be the main factor that induces corrosion in stainless steel. The noble potential caused by the action of aerobic microorganisms varies in the noble potential reached by seasonal variation of immersed fresh water, brackish water or seawater. The higher the potential level, the greater the likelihood of crevice or pitting corrosion occurring in the stainless steel. The occurrence of crevice corrosion or pitting corrosion of stainless steel is closely related to the immersion potential. The immersion potential becomes noble,
Exceeding the crevice corrosion re-passivation potential, which is the critical potential for crevice corrosion, may cause crevice corrosion. Further, when the immersion potential becomes noble and exceeds the pitting potential, pitting occurs (Shigeo Tsujikawa, Takahiro Hisamatsu: Anticorrosion technology, 29, 37 (19)
80)). Crevice corrosion is much more likely to occur than pitting, and the pitting potential is higher than the crevice corrosion re-passivation potential. In actual use of stainless steel, it is extremely difficult to avoid a clearance structure due to a structure such as a welded portion or a screw. The noble potential causes corrosion of the crevice structure and also hinders re-passivation of the passive film. Therefore, it is necessary to evaluate the corrosion resistance of stainless steel against crevice corrosion in river water, seawater, and the like under conditions that consider the effect of noble potential due to microbial action.
As a conventional technique for evaluating the corrosion resistance of stainless steel against microbial corrosion, a method using a cultured microorganism (Japanese Unexamined Patent Application Publication No.
JP-A-299497), a method using an oxidizing enzyme (JP-A-6-78794, JP-A-8-68774), and a corrosion test apparatus in consideration of microbial corrosion (Japanese Patent Laid-Open No. 5-79874).
264497). Although different from microbial corrosion, there is a 6% ferric chloride solution immersion test method (ASTM G48) as a method for evaluating the crevice corrosion resistance of stainless steel by the potential noble action of an oxidizing agent.
【０００３】[0003]
【発明が解決しようとする課題】これまで、微生物腐食
に対するステンレス鋼の耐食性を評価する技術はいくつ
か提案されているものの、微生物作用によるステンレス
鋼の電位貴化メカニズムが十分に解明されてこなかった
（明石正恒 第１２５回腐食防食シンポジウム資料Ｐ．
５５−Ｐ．７０）ために、未だに確立した耐食性を評価
する方法が確立されていないのが現状である。例えば、
培養微生物を用いる方法（特開平１１−２９９４９７号
公報）では微生物腐食への影響が示唆されている培養可
能な微生物種を単一種加えることにより、耐食性を評価
する方法であり、環境中の複合的な微生物作用による電
位貴化を考慮したものではない。また、酸化酵素を用い
た方法（特開平６−７８７９４号公報、特開平８−６８
７７４号公報）は電位貴化作用に着目した耐食試験法で
あるものの、酵素反応を用いるため、発生する貴化電位
を安定に設定できない問題がある。さらに、微生物腐食
を考慮した腐食試験装置（特開平５−２６４４９７号公
報）も電位貴化の耐食性への影響を考慮した方法ではな
い。また、ステンレス鋼の耐すきま腐食性を評価する方
法として用いられる6% 塩化第二鉄溶液浸漬試験法（AST
M G48）は、河川水や海水には存在しない非常に高濃度
の第二鉄イオンの酸化力を用いるため、微生物作用によ
る電位貴化に起因するすきま腐食発生とは全く異なるメ
カニズムに基づく耐食試験方法である。以上のように、
従来の耐食性評価方法にはさまざまな問題があった。Although several techniques for evaluating the corrosion resistance of stainless steel against microbial corrosion have been proposed, the mechanism of noble potential of stainless steel by the action of microorganisms has not been sufficiently elucidated. (Masatake Akashi, 125th Corrosion and Corrosion Symposium, p.
55-P. 70) Therefore, at present, there is no established method for evaluating the established corrosion resistance. For example,
A method using a cultured microorganism (Japanese Patent Laid-Open No. 11-299497) is a method for evaluating corrosion resistance by adding a single culturable microorganism species that is suggested to have an effect on microbial corrosion. It does not take into account potential nobleness due to the action of microorganisms. Further, a method using an oxidase (JP-A-6-78794, JP-A-8-68)
No. 774) is a corrosion resistance test method which focuses on the noble potential effect, but has a problem that the generated noble potential cannot be set stably because an enzymatic reaction is used. Furthermore, a corrosion test apparatus (JP-A-5-264497) considering microbial corrosion is not a method in which the effect of noble potential on corrosion resistance is considered. The 6% ferric chloride solution immersion test method (AST) is used to evaluate the crevice corrosion resistance of stainless steel.
MG48) uses the oxidizing power of very high concentrations of ferric ion that does not exist in river water or seawater, so it is a corrosion resistance test based on a completely different mechanism from crevice corrosion caused by potential nobleness due to microbial action Is the way. As mentioned above,
The conventional corrosion resistance evaluation method has various problems.
【０００４】さて、耐食性を評価する最も直接的な方法
は、現場の水環境に鋼材を浸漬して、耐食性を確認する
ことである。しかしながら、実環境で耐食試験を行うこ
とは、経済的にも、あるいは、期間的な問題からも容易
ではない。場合によっては、実環境での耐食試験を未実
施のまま、鋼材を使用しなければならない場合もあり得
る。このような観点から、実験室レベルでより短期間に
耐食性を評価できることが望ましい。しかしながら、実
環境と同じ腐食環境を実験室的に再現することは極めて
難しい。実環境の水質分析から、腐食に関与する物理化
学パラメーター、例えば、pH、溶存酸素濃度、各種イオ
ン濃度 などは、比較的容易に得られる。しかし、環境
中に棲息する微生物の菌相は、場所ごとに大きく異な
り、かつ、季節変動するので、その情報を入手すること
は難しい。また、環境中の微生物のうち、培養できるも
のはせいぜい１０％程度であると考えられている。つま
り、大多数を占める残り９０%程度の微生物は、培養が
困難であると考えられている。したがって、たとえ、実
環境から微生物を含んだ水を採水することが可能であっ
ても、鋼材が用いられる現場と同じ微生物環境を実験室
的に再現することは、事実上、困難である。以上の理由
から、環境に存在する微生物をそのまま用いるのではな
く、微生物による腐食の本質的な原因を物理化学的な原
因に帰結させて、耐食性を評価する必要がある。現状で
は、このような耐食性を評価する方法が確立されていな
い。The most direct method for evaluating corrosion resistance is to immerse a steel material in a water environment at a site to check the corrosion resistance. However, conducting a corrosion test in a real environment is not easy, either economically or because of periodical issues. In some cases, it may be necessary to use steel without performing a corrosion test in a real environment. From such a viewpoint, it is desirable that the corrosion resistance can be evaluated in a shorter time at the laboratory level. However, it is extremely difficult to reproduce the same corrosive environment as a real environment in a laboratory. From the analysis of water quality in the real environment, physicochemical parameters related to corrosion, such as pH, dissolved oxygen concentration, and various ion concentrations, can be obtained relatively easily. However, the microflora of microorganisms that live in the environment vary greatly from place to place and vary seasonally, making it difficult to obtain that information. It is considered that at most about 10% of the microorganisms in the environment can be cultured. That is, it is considered that the remaining about 90% of the microorganisms, which make up the majority, are difficult to culture. Therefore, even if it is possible to collect water containing microorganisms from the real environment, it is practically difficult to reproduce in a laboratory the same microbial environment at the site where the steel material is used. For the above reasons, it is necessary to evaluate corrosion resistance not by using microorganisms existing in the environment as it is, but by attributing essence of corrosion by microorganisms to physicochemical causes. At present, a method for evaluating such corrosion resistance has not been established.
【０００５】本発明は、微生物作用に特徴的なステンレ
ス鋼の電位貴化を人為的に再現可能とし、かつ、電位貴
化にいたるまでの時間を短縮化して耐食性評価を効率的
に実施可能な試験液および耐食性評価方法を提供するこ
とを目的とする。The present invention makes it possible to artificially reproduce the noble potential of stainless steel, which is characteristic of microbial action, and to efficiently evaluate the corrosion resistance by shortening the time until the noble potential. It is an object to provide a test solution and a method for evaluating corrosion resistance.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、微生物作
用によるステンレス鋼の電位貴化を模してかつ、促進化
して、ステンレス鋼を電位貴化させてステンレス鋼の耐
食性を評価する試験液を提供する。すなわち本発明は、 （ａ） 過酸化水素を1L あたり1 mmol以上30 mmol 以
下含有してpH3.0以上pH8.2以下であることを特徴とする
ステンレス鋼の耐すきま腐食性の評価用試験液、 （ｂ） 浸漬したステンレス鋼の貴化電位を470mV
（飽和KCl Ag/AgCl電極を参照電極とした電位値）以上
になるように、過酸化水素を1L あたり1 mmol以上30mmo
l 以下とpH3.0以上pH3.9以下の範囲で調整したことを特
徴とするステンレス鋼の耐孔食性および耐すきま腐食性
の評価用試験液。 （ｃ） （ａ）または（ｂ）に記載の試験液にステンレ
ス鋼を浸漬することによりステンレス鋼の耐食性を評価
する方法、 （ｄ） ステンレス鋼の目標とする浸漬電位に応じて過
酸化水素濃度およびpHを調整することを特徴とする
（ｃ）のステンレス鋼の耐食性を評価する方法、を内容
とするものである。Means for Solving the Problems The present inventors simulated and promoted the noble potential of stainless steel by the action of microorganisms, and conducted a test to evaluate the corrosion resistance of stainless steel by making stainless steel noble. Provide liquid. That is, the present invention provides: (a) a test solution for evaluating crevice corrosion resistance of stainless steel, characterized by containing 1 to 30 mmol of hydrogen peroxide per liter and having a pH of 3.0 to 8.2. (B) The noble potential of immersed stainless steel is 470 mV
(Potential value with saturated KCl Ag / AgCl electrode as reference electrode)
Test liquid for evaluating pitting corrosion resistance and crevice corrosion resistance of stainless steel, characterized in that the pH is adjusted to l or less and pH 3.0 or more and pH 3.9 or less. (C) A method for evaluating the corrosion resistance of stainless steel by immersing the stainless steel in the test solution described in (a) or (b). (D) Hydrogen peroxide concentration according to the target immersion potential of the stainless steel. And (c) a method for evaluating the corrosion resistance of stainless steel, which comprises adjusting pH.
【０００７】[0007]
【発明の実施の形態】本発明者らは、従来、微生物作用
によるステンレス鋼の浸漬電位の電位貴化原因が解明さ
れてこなかったことが、微生物作用に対する耐食性評価
方法が確立されない根本的な問題であると捉え、鋭意、
解析・検討した結果、過酸化水素と酸性化の作用が組み
合わさることにより微生物作用によるステンレス鋼の電
位貴化が起こることを解明した。したがって、過酸化水
素濃度とpHの条件設定した溶液によって、ステンレス鋼
の浸漬電位を人為的に貴化することを考えた。実際の河
川水、あるいは、海水等でのステンレス鋼の貴化電位の
実測値との比較によって、実環境での微生物作用による
貴化電位を短時間で再現し得るpHおよび過酸化水素の濃
度範囲を特定化してステンレス鋼の耐すきま腐食性およ
び耐孔食性を促進化して評価する試験液および耐食性評
価方法を発明したのである。BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have heretofore failed to elucidate the cause of noble potential of the immersion potential of stainless steel due to microbial action, which is a fundamental problem that a method for evaluating corrosion resistance to microbial action has not been established. Enthusiastically,
As a result of the analysis and investigation, it was clarified that the combination of hydrogen peroxide and the action of acidification caused the noble potential of stainless steel by microbial action. Therefore, it was considered that the immersion potential of stainless steel was artificially precious by a solution in which the conditions of hydrogen peroxide concentration and pH were set. By comparing the noble potential of stainless steel in actual river water or seawater with the measured value, the concentration range of pH and hydrogen peroxide that can reproduce the noble potential by microbial action in a real environment in a short time The present invention has invented a test solution and a method for evaluating corrosion resistance in which stainless steel is evaluated by promoting crevice corrosion resistance and pitting corrosion resistance.
【０００８】以下に本発明を詳細に説明する。Hereinafter, the present invention will be described in detail.
【０００９】好気性微生物作用によるステンレス鋼の電
位貴化は、浸漬される淡水、汽水あるいは海水の季節変
動によって、到達する貴化電位が変動する。ここで貴化
電位とは電位の気化によって到達する定常的な浸漬電位
（自然電位あるいは腐食電位ともいう）うぃ意味する。The noble potential of stainless steel caused by the action of aerobic microorganisms varies depending on the seasonal fluctuation of immersed fresh water, brackish water or seawater. Here, the noble potential refers to a constant immersion potential (also referred to as a spontaneous potential or corrosion potential) reached by vaporization of the potential.
【００１０】電位レベルが高くなるほど、ステンレス鋼
にすきま腐食あるいは孔食が発生する可能性が高くな
る。河川水、あるいは、海水中で、さまざまな季節にス
テンレス鋼の浸漬電位の測定を実施した結果、淡水およ
び海水で+150mV以上+470mV以下の電位が得られた（いづ
れも飽和KCl Ag/AgCl電極を参照電極とした電位値で記
してある。）。そこで本発明者らは、一般的な河川水や
海水であれば、+150mV以上+470mV 以下（飽和KCl Ag/Ag
Cl電極基準）の電位範囲に微生物作用による貴化電位が
達することになるものと考えた。本発明者らは、このよ
うな微生物作用によるステンレス鋼の電位貴化がステン
レス鋼が接触する液への過酸化水素添加とpH調整によっ
て再現可能であることを見いだした。以下にステンレス
鋼に接触して電位貴化させるための試験液の調製方法を
示す。 （１） 試験液のベースとなる水あるいは水溶液として
は、ステンレス鋼を使用しようとする実環境で、ステン
レス鋼に接触する可能性がある河川水、湖沼水、地下
水、農業用水、工業用水、循環冷却水などの淡水や、汽
水、海水を採水したものを用意する。可能であれば、滅
菌したものを用意することがより望ましい。滅菌方法と
してはフィルタ滅菌が望ましいが、オートクレーブ滅菌
も適用可能である。 （２） 試験液のベースとなる水あるいは水溶液として
（１）に記載の実使用環境からの採水が不可能な場合に
は、これらの含有成分濃度を人工的に模した水溶液を用
いることも可能である。例えば海水に関しては、人工海
水などが使用可能である。尚、実環境水の成分濃度も未
知の場合には、類似した主要成分を含む水溶液であれば
使用可能である。可能であれば、滅菌したものを用意す
ることがより望ましい。滅菌方法としてはフィルタ滅菌
が望ましいが、オートクレーブ滅菌も適用可能である。 （３） （１）あるいは（２）で用意した試験液のベー
スとなる水あるいは水溶液に、過酸化水素を１Ｌあたり
1 mmol 以上 30 mmol 以下の濃度範囲で添加して混合
する。 （４） ステンレス鋼の耐すきま腐食性を評価する試験
液を調製するためには、（３）に記載の水溶液に塩酸、
硫酸、硝酸、炭酸あるいは酢酸、乳酸、プロピオン酸、
ギ酸、酪酸を単独であるいは組み合わせて用いてpHを調
整する。海水や河川水などで観測されるような+150mV
（飽和KCl Ag/AgCl電極基準）以上の貴化電位となるよ
うに、調整後のpHは pH3.0以上pH8.2以下の範囲で耐食
性を評価したいステンレス鋼の目標とする貴化電位を与
える pHに調製する。 （５） ステンレス鋼の耐孔食性および耐すきま腐食性
を評価する試験液を調製するためには、（３）に記載の
水溶液に塩酸、硫酸、硝酸、炭酸あるいは酢酸、乳酸、
プロピオン酸、ギ酸、酪酸を単独であるいは組み合わせ
て用いてpHを調整する。pH3.0以上pH3.9の範囲で、すな
わち+470mV （飽和KCl Ag/AgCl電極基準）以上の貴化電
位になるように調製する。例えば、過酸化水素濃度が試
験液１Ｌあたり 1 mmol含有する場合には、pH3.0、過酸
化水素濃度が試験液１Ｌあたり 30mmol含有する場合に
は、pH3.9でステンレス鋼の貴化電位+470mV （飽和KCl
Ag/AgCl電極基準）が達成され得る。[0010] The higher the potential level, the greater the likelihood of crevice or pitting corrosion occurring in the stainless steel. As a result of measuring the immersion potential of stainless steel in river water or seawater in various seasons, a potential of +150 mV to +470 mV was obtained in freshwater and seawater (both saturated KCl Ag / AgCl electrodes) Is described as a potential value with reference to the reference electrode.) Therefore, the present inventors have found that if general river water or seawater is used, +150 mV or more and +470 mV or less (saturated KCl Ag / Ag
It was considered that the noble potential by microbial action would reach the potential range of Cl electrode standard). The present inventors have found that the noble potential of stainless steel due to such a microbial action can be reproduced by adding hydrogen peroxide to a liquid in contact with the stainless steel and adjusting the pH. Hereinafter, a method of preparing a test solution for making a potential noble by contacting stainless steel will be described. (1) As the water or aqueous solution used as the base of the test solution, river water, lake water, groundwater, agricultural water, industrial water, circulation that may come into contact with stainless steel in the actual environment where stainless steel is to be used Prepare fresh water such as cooling water, brackish water, and seawater. If possible, it is more desirable to prepare a sterilized one. As a sterilization method, filter sterilization is preferable, but autoclave sterilization is also applicable. (2) When it is not possible to collect water from the actual use environment described in (1) as the base water or aqueous solution of the test solution, an aqueous solution artificially simulating the concentration of these components may be used. It is possible. For example, as for seawater, artificial seawater or the like can be used. If the component concentration of the actual environmental water is also unknown, any aqueous solution containing similar main components can be used. If possible, it is more desirable to prepare a sterilized one. As a sterilization method, filter sterilization is preferable, but autoclave sterilization is also applicable. (3) Add hydrogen peroxide per liter to the water or aqueous solution used as the base of the test solution prepared in (1) or (2).
Add and mix in a concentration range of 1 mmol or more and 30 mmol or less. (4) To prepare a test solution for evaluating the crevice corrosion resistance of stainless steel, hydrochloric acid is added to the aqueous solution described in (3).
Sulfuric acid, nitric acid, carbonic acid or acetic acid, lactic acid, propionic acid,
The pH is adjusted using formic acid or butyric acid alone or in combination. + 150mV as observed in seawater or river water
(Saturated KCl Ag / AgCl electrode standard) Provide the target noble potential of stainless steel whose corrosion resistance is to be evaluated in the range of pH3.0 to pH8.2 so that the noble potential is higher than (saturated KCl Ag / AgCl electrode standard). Adjust to pH. (5) In order to prepare a test solution for evaluating the pitting corrosion resistance and crevice corrosion resistance of stainless steel, hydrochloric acid, sulfuric acid, nitric acid, carbonic acid or acetic acid, lactic acid, or the like is added to the aqueous solution described in (3).
Adjust the pH with propionic acid, formic acid, butyric acid alone or in combination. It is adjusted so as to have a noble potential in a range of pH 3.0 or more and pH 3.9, that is, at least +470 mV (based on a saturated KCl Ag / AgCl electrode). For example, when the hydrogen peroxide concentration is 1 mmol per 1 L of the test solution, the pH is 3.0. When the hydrogen peroxide concentration is 30 mmol per 1 L of the test solution, the pH is 3.9 and the noble potential of stainless steel is +3.0. 470mV (saturated KCl
Ag / AgCl electrode reference) can be achieved.
【００１１】以上のように、ステンレス鋼の耐食性を評
価する試験液を調製する。なお、過酸化水素の添加とpH
調製の順序は同時でも逆でも可能である。As described above, a test solution for evaluating the corrosion resistance of stainless steel is prepared. Addition of hydrogen peroxide and pH
The order of preparation can be simultaneous or reversed.
【００１２】上記（４）あるいは（５）に記載の試験液
にステンレス鋼を接触させることにより、ステンレス鋼
の浸漬電位は貴化する。通常、ステンレス鋼を河川水や
海水に浸漬すると、微生物作用によって定常的な貴化電
位に達するまでには一週間以上の長期間を要する。しか
し、本試験液にステンレス鋼を接触させることにより、
数時間から１日程度で定常的な貴化電位に達することが
可能となる。このように、本試験液は微生物作用による
電位貴化と比較してステンレス鋼の電位貴化に要する時
間を短縮する効果がある。By bringing the stainless steel into contact with the test solution described in the above (4) or (5), the immersion potential of the stainless steel becomes noble. Normally, when stainless steel is immersed in river water or seawater, it takes a long time of one week or more to reach a steady noble potential by microbial action. However, by contacting stainless steel with this test solution,
It is possible to reach a steady noble potential in several hours to one day. As described above, the present test solution has an effect of shortening the time required for the noble potential of stainless steel as compared with the noble potential by the action of microorganisms.
【００１３】尚、一般的なステンレス鋼の耐食性評価に
は、河川、海水で観測された最高レベルの貴化電位以上
の高い電位に設定して、より厳しい腐食環境で耐食性を
評価するべきである。したがって、（５）に記載の試験
液を用いて耐すきま腐食性および耐孔食性を評価するこ
とが好ましい。In general, in evaluating the corrosion resistance of stainless steel, it is necessary to evaluate the corrosion resistance in a more severe corrosive environment by setting the potential to be higher than the highest level of noble potential observed in rivers and seawater. . Therefore, it is preferable to evaluate crevice corrosion resistance and pitting corrosion resistance using the test liquid described in (5).
【００１４】次に本発明の試験液を用いてステンレス鋼
の耐食性を評価する方法を説明する。Next, a method for evaluating the corrosion resistance of stainless steel using the test solution of the present invention will be described.
【００１５】まず、耐食性を評価するためにはステンレ
ス鋼を本発明の試験液に浸漬あるいは接触させる。ここ
で、耐食性を評価しようとするステンレス鋼の浸漬電位
を、使用しようとする水環境に棲息する微生物作用によ
る最高レベルの貴化電位と同等あるいはそれ以上の電位
に設定することで、微生物作用に対する耐食性を評価す
ることが可能となる。First, in order to evaluate corrosion resistance, stainless steel is immersed in or brought into contact with the test solution of the present invention. Here, by setting the immersion potential of the stainless steel for which corrosion resistance is to be evaluated to a potential equal to or higher than the highest level of noble potential due to the microbial action that inhabits the water environment to be used, it is possible to reduce the microbial action. It becomes possible to evaluate corrosion resistance.
【００１６】ステンレス鋼の浸漬電位を、このような目
標電位に設定するために過酸化水素濃度とpHを調整して
試験液を作成する方法について説明する。A method for preparing a test solution by adjusting the concentration of hydrogen peroxide and the pH in order to set the immersion potential of stainless steel at such a target potential will be described.
【００１７】本発明の試験液のｐＨ3.0以上pH8.2以下に
おいて、pHが低くなるほどステンレス鋼の浸漬電位は上
がる。また、本発明の試験液の過酸化水素濃度が１Ｌあ
たり1mmol以上30mmol以下において、過酸化水素濃度が
高くなるほどステンレス鋼の浸漬電位は上がる。例え
ば、過酸化水素濃度が１Ｌあたり1mmolでpH8.2の場合、
ステンレス鋼の浸漬電位は約150mV（飽和KCl Ag/AgCl電
極基準）にまで貴化する。また、過酸化水素濃度が１Ｌ
あたり30mmolでpH3の場合、ステンレス鋼の浸漬電位は
約550mV（飽和KCl Ag/AgCl電極基準）にまで貴化する。
この間の所望の貴化電位を過酸化水素濃度とpHの組み合
わせで設定してステンレス鋼の耐食性評価を実施でき
る。When the pH of the test solution of the present invention is in the range of pH 3.0 to pH 8.2, the immersion potential of stainless steel increases as the pH decreases. When the concentration of hydrogen peroxide in the test solution of the present invention is 1 mmol or more and 30 mmol or less per 1 L, the immersion potential of stainless steel increases as the concentration of hydrogen peroxide increases. For example, when the concentration of hydrogen peroxide is 1 mmol per liter and the pH is 8.2,
The immersion potential of stainless steel is increased to about 150 mV (based on the saturated KCl Ag / AgCl electrode). In addition, hydrogen peroxide concentration is 1L
In the case of pH 3 at 30 mmol per unit, the immersion potential of stainless steel becomes noble to about 550 mV (based on a saturated KCl Ag / AgCl electrode).
During this time, the desired noble potential can be set by a combination of the hydrogen peroxide concentration and the pH to evaluate the corrosion resistance of stainless steel.
【００１８】次に、ステンレス鋼の浸漬電位を目標とす
る電位に設定した状態での耐食性評価の実施方法につい
て説明する。ここで目標とする電位とは、海水や河川水
などに浸漬したステンレス鋼で観測される貴化した電位
と同等以上の、耐食性を評価したい電位を意味する。Next, a method for evaluating corrosion resistance in a state where the immersion potential of stainless steel is set to a target potential will be described. Here, the target potential means a potential at which corrosion resistance is to be evaluated, which is equal to or higher than the noble potential observed in stainless steel immersed in seawater, river water, or the like.
【００１９】耐すきま腐食性を評価しようとする場合
は、すきま構造を付与したステンレス鋼試験片につい
て、（４）に記載の試験液に貴化電位となってから任意
の時間浸漬後、試験片を取り出して、すきま腐食発生の
有無、すきま腐食の発生数、分布、面積、あるいは試験
片の腐食減量を測定することにより、ステンレス鋼の耐
すきま腐食性を評価することができる。一般的な、すき
ま構造を付与したステンレス鋼にたいする腐食試験とし
て、例えば、マルチクレビス試験法（ＡＳＴＭ Ｇ４８
−７６）がある。すきま形成治具によってステンレス鋼
表面に４０個程度のすきまを作って、一定期間経過の
後、すきま腐食の発生数によって耐食性を評価する方法
であり、本発明の試験液に接触させることによる電位貴
化にたいする耐すきま腐食性の評価にも適用可能であ
る。なお、耐すきま腐食性を評価する温度としては、自
然水環境に棲息する一般的な好気性微生物の生育に適し
た温度と同範囲の１５℃以上４０℃以下で実施すること
が望ましいが、本発明はこの温度範囲に限定されるもの
ではない。In order to evaluate crevice corrosion resistance, a stainless steel test piece having a clearance structure is immersed in the test solution described in (4) for an arbitrary time after the noble potential has been reached, Then, the crevice corrosion resistance of the stainless steel can be evaluated by measuring the presence or absence of crevice corrosion, the number, distribution, and area of crevice corrosion, or the weight loss of the test specimen. As a general corrosion test for stainless steel having a clearance structure, for example, a multi-clevis test method (ASTM G48)
-76). This is a method in which about 40 gaps are formed on the stainless steel surface with a gap forming jig, and after a certain period of time, the corrosion resistance is evaluated by the number of crevice corrosion. It can also be applied to the evaluation of crevice corrosion resistance to erosion. The temperature at which crevice corrosion resistance is evaluated is preferably 15 ° C or more and 40 ° C or less, which is the same range as the temperature suitable for the growth of general aerobic microorganisms living in natural water environments. The invention is not limited to this temperature range.
【００２０】また、耐孔食性および耐すきま腐食性を評
価しようとする場合には、ステンレス鋼試験片を用い
て、（５）に記載の試験液に貴化電位となってから任意
の時間接触させることにより、耐孔食性および耐すきま
腐食性を評価することができる。試験片表面を直接観察
して孔食の有無を調べることや、孔食やすきま腐食の発
生数、分布、腐食面積、試験片の重量変化による腐食減
量を測定するなどして、耐食性を評価することができ
る。なお、耐孔食性を評価する温度としては、自然水環
境に棲息する一般的な好気性微生物の生育に適した温度
と同範囲の１５℃以上４０℃以下で実施することが望ま
しいが、本発明はこの温度範囲に限定されるものではな
い。When the pitting corrosion resistance and crevice corrosion resistance are to be evaluated, a stainless steel test piece is used to contact the test solution described in (5) for an arbitrary time after the noble potential is reached. By doing so, pitting corrosion resistance and crevice corrosion resistance can be evaluated. Evaluate corrosion resistance by directly observing the specimen surface to check for pitting corrosion, and by measuring the number of pitting and crevice corrosion occurrences, distribution, corrosion area, and weight loss due to weight change of the specimen. be able to. The temperature at which the pitting corrosion resistance is evaluated is preferably 15 ° C. or more and 40 ° C. or less, which is the same range as the temperature suitable for the growth of general aerobic microorganisms living in a natural water environment. Is not limited to this temperature range.
【００２１】以下に本発明の構成要件の限定理由を述べ
る。 （ａ）過酸化水素濃度としては試験液１Ｌあたり1 mmol
以上 30 mmol 以下の範囲に限定される。これは、ステ
ンレス鋼の電位は過酸化水素濃度が試験液１Ｌあたり30
mmol以下では、過酸化水素の濃度に依存して浸漬電位が
貴化する傾向が顕著であるが、過酸化水素濃度が試験液
１Ｌあたり30 mmolを超えると、過酸化水素の濃度増加
に依存する浸漬電位上昇傾向が著しく鈍化する。したが
って、浸漬電位の過酸化水素濃度依存性が顕著にみられ
る試験液１Ｌあたり30 mmol以下とした。The reasons for limiting the constituent elements of the present invention will be described below. (A) The concentration of hydrogen peroxide is 1 mmol per 1 L of test solution
It is limited to the range of 30 mmol or less. This means that the potential of stainless steel is 30% hydrogen peroxide concentration per liter of test solution.
When the concentration is less than mmol, the tendency that the immersion potential becomes noble depending on the concentration of hydrogen peroxide is remarkable, but when the concentration of hydrogen peroxide exceeds 30 mmol per 1 L of the test solution, it depends on the increase in the concentration of hydrogen peroxide. The tendency of the immersion potential to rise significantly slows down. Therefore, the immersion potential was set to 30 mmol or less per liter of the test solution in which the hydrogen peroxide concentration dependency was remarkably observed.
【００２２】また、河川水あるいは海水で実測した中
で、最もpHが高いのは、8.2であり、ステンレス鋼の浸
漬電位は+150mV（飽和KCl Ag/AgCl電極基準）が貴化電
位としては最低であった。過酸化水素濃度が1 mmol未満
であると、PH8.2においてステンレス鋼の浸漬電位は+15
0mV（飽和KCl Ag/AgCl電極基準）に達しなかった。ま
た、過酸化水素濃度が1mmol未満であると電位貴化に１
日以上の長時間を要するようになり、貴化電位も不安定
になり、貴化電位に達するまでの時間が短縮化できなく
なる傾向がある。従って、過酸化水素濃度は、1 mmol
以上 30 mmol以下の範囲に限定される。 （ｂ）耐すきま腐食性を評価する試験液のpHとしては、
pH3.0 以上 pH8.2 以下の範囲に限定される。これは、
河川水あるいは海水で実測した中で、最もpHが高いの
は、8.2であり、8.2を超えるpHは観測されなかった。ま
た、よりアルカリ側の条件ほど、浸漬電位は、pHに依存
して低くなるため、電位貴化による腐食発生を抑制する
方向へむかう。そこで、pHは8.2以下とした。また、
（ａ）で限定した過酸化水素濃度範囲で最も低い浸漬電
位を与えるのは試験液１Ｌあたり1 mmolの過酸化水素の
場合である。この場合、自然水環境で実測された最高レ
ベルの貴化電位である＋470ｍＶ（飽和KCl Ag/AgCl電極
を参照電極とした電位値）にまで電位貴化させるため
に、ｐＨ３．０にする必要がある。また、ｐＨ３未満で
は、電位貴化以外のステンレス鋼の腐食要因として酸性
条件による腐食が懸念される。したがって、耐すきま腐
食性を評価する試験液のｐＨは、ｐＨ３．０以上ｐＨ
８．２以下の範囲に限定される。なお、pH調製に用いる
酸として、塩酸、硫酸、硝酸、炭酸あるいは有機酸（酢
酸、乳酸、プロピオン酸、ギ酸、酪酸）を単独あるいは
組み合わせて用いることが可能である。 （ｃ）耐孔食性および耐すきま腐食性を評価する試験液
のpHとしては、pH3.0 以上 pH３．９以下の範囲に限定
される。耐孔食性は、自然水環境で実測される最高レベ
ルの貴化電位以上の電位において評価されることが望ま
しい。（ａ）で限定した過酸化水素濃度範囲で自然水環
境で実測された最高レベルの貴化電位である＋470ｍＶ
（飽和KCl Ag/AgCl電極を参照電極とした電位値）と同
等以上の貴化電位を発生させることが望ましい。過酸化
水素濃度が試験液１Ｌあたり1 mmolの場合には、ｐＨ
３．０、過酸化水素濃度が試験液１Ｌあたり30 mmolの
場合にはｐＨ３．９でステンレス鋼の貴化電位が+470mV
（飽和KCl Ag/AgCl電極を参照電極とした電位値）にな
り得る。ｐＨ３未満では、電位貴化以外のステンレス鋼
の腐食要因として酸性条件による腐食が懸念される。ま
た、pH3.9を超えると、過酸化水素濃度が試験液1Lあた
り、1 mmol 以上30mmol以下の範囲では、+470mV（飽和K
Cl Ag/AgCl電極を参照電極とした電位値）と同等以上の
貴化電位を再現することが難しい。したがって、ｐＨは
ｐＨ３．０以上ｐＨ３．９以下の範囲に限定されるな
お、pH調製に用いる酸として、塩酸、硫酸、硝酸、炭酸
あるいは有機酸（酢酸、乳酸、プロピオン酸、ギ酸、酪
酸）を単独あるいは組み合わせて用いることが可能であ
る。Among the measured values of river water or seawater, the highest pH is 8.2, and the immersion potential of stainless steel is +150 mV (based on saturated KCl Ag / AgCl electrode) as the lowest noble potential. Met. When the hydrogen peroxide concentration is less than 1 mmol, the immersion potential of stainless steel at PH8.2 is +15
0 mV (based on the saturated KCl Ag / AgCl electrode) was not reached. If the hydrogen peroxide concentration is less than 1 mmol, the potential noble
A longer time than a day is required, the noble potential becomes unstable, and the time required to reach the noble potential tends not to be reduced. Therefore, the concentration of hydrogen peroxide is 1 mmol
It is limited to the range of 30 mmol or less. (B) The pH of the test solution for evaluating crevice corrosion resistance is as follows:
It is limited to the range from pH3.0 to pH8.2. this is,
The highest pH measured in river water or seawater was 8.2, and no pH exceeding 8.2 was observed. In addition, since the immersion potential becomes lower depending on the pH as the condition becomes more alkaline, the immersion potential tends to suppress the occurrence of corrosion due to noble potential. Therefore, the pH was set to 8.2 or less. Also,
The lowest immersion potential in the hydrogen peroxide concentration range defined in (a) is given in the case of 1 mmol of hydrogen peroxide per 1 L of the test solution. In this case, in order to make the potential noble to +470 mV (potential value using a saturated KCl Ag / AgCl electrode as a reference electrode) which is the highest level noble potential measured in a natural water environment, it is necessary to adjust the pH to 3.0. is there. If the pH is less than 3, corrosion due to acidic conditions is a concern other than corrosion potential of stainless steel other than noble potential. Therefore, the pH of the test solution for evaluating crevice corrosion resistance is pH 3.0 or more.
It is limited to the range of 8.2 or less. In addition, as an acid used for pH adjustment, hydrochloric acid, sulfuric acid, nitric acid, carbonic acid or an organic acid (acetic acid, lactic acid, propionic acid, formic acid, butyric acid) can be used alone or in combination. (C) The pH of the test solution for evaluating pitting corrosion resistance and crevice corrosion resistance is limited to a range of pH 3.0 to pH 3.9. It is desirable that the pitting resistance be evaluated at a potential equal to or higher than the highest level of noble potential measured in a natural water environment. +470 mV which is the highest level of noble potential measured in a natural water environment within the hydrogen peroxide concentration range defined in (a).
It is desirable to generate a noble potential equal to or higher than (a potential value using a saturated KCl Ag / AgCl electrode as a reference electrode). If the concentration of hydrogen peroxide is 1 mmol / L of test solution, pH
3.0, when the hydrogen peroxide concentration is 30 mmol per 1 L of the test solution, the noble potential of stainless steel is +470 mV at pH 3.9.
(Potential value using a saturated KCl Ag / AgCl electrode as a reference electrode). If the pH is less than 3, corrosion due to acidic conditions is a concern as a corrosion factor of stainless steel other than noble potential. In addition, if the pH exceeds 3.9, the concentration of hydrogen peroxide is +470 mV (saturated K
It is difficult to reproduce a noble potential equal to or higher than (a potential value using a Cl Ag / AgCl electrode as a reference electrode). Therefore, the pH is limited to a range of pH 3.0 or more and pH 3.9 or less. As an acid used for pH adjustment, hydrochloric acid, sulfuric acid, nitric acid, carbonic acid or an organic acid (acetic acid, lactic acid, propionic acid, formic acid, butyric acid) is used. They can be used alone or in combination.
【００２３】[0023]
【実施例】以下、本発明を実施例により説明する。 実施例１ pHと過酸化水素濃度の組み合わせ効果によるステンレス
鋼の電位貴化：浸漬電位の測定：30w×25l×2tmmの寸法
のステンレス鋼 SUS304試験片の全面をエメリー400番研
磨紙を用いて湿式研磨したあと、上端にリード線をハン
ダ付けし、アセトン中にて脱脂をおこなった。ｐＨと過
酸化水素濃度をさまざまな条件に濃度設定した試験液を
用意して、上記試験片を浸漬した。pH は pH8.2, pH6.
0, pH 3.9, pH3.0 とし、過酸化水素濃度は試験液１Ｌ
あたり 0 mmol, 0.001 mmol, 0.01 mmol, 0.03 mmol,
0.1 mmol, 0.3 mmol, 1 mmol, 3 mmol, 10 mmol,30 mmo
l, 100 mmol, 1000 mmol とした。浸漬電位の測定を24h
継続しておこない、定常的な貴化電位を測定した。電位
は、いずれも飽和KCl Ag/AgCl電極を参照電極とする値
で示した。The present invention will be described below with reference to examples. Example 1 Potential nobleness of stainless steel by the combined effect of pH and hydrogen peroxide concentration: Measurement of immersion potential: stainless steel with dimensions of 30w x 25l x 2tmm SUS304 specimen was wet-processed using Emery 400 abrasive paper. After polishing, a lead wire was soldered to the upper end, and degreased in acetone. The test pieces were immersed in test liquids in which the pH and the concentration of hydrogen peroxide were set under various conditions. pH is pH8.2, pH6.
0, pH 3.9, pH 3.0, and the concentration of hydrogen peroxide is 1L of test solution.
0 mmol, 0.001 mmol, 0.01 mmol, 0.03 mmol,
0.1 mmol, 0.3 mmol, 1 mmol, 3 mmol, 10 mmol, 30 mmo
l, 100 mmol, and 1000 mmol. 24 hours immersion potential measurement
The test was continuously performed, and a steady noble potential was measured. The potentials are shown as values using a saturated KCl Ag / AgCl electrode as a reference electrode.
【００２４】耐すきま腐食性を評価する場合（表１）に
は、貴化電位が+150mV（飽和KCl Ag/AgCl電極基準）以
上となる場合に、判定○とした。ただし、定常的な貴化
電位に達するまでの時間が２４ｈｒを超える場合には迅
速な電位貴化再現が困難であるので耐すきま腐食性評価
には不適であるため判定△とした。また、過酸化水素濃
度が１Ｌあたり30mmolを超えるような高濃度の条件で
は、過酸化水素使用のコスト負担が増大することと、実
際の微生物原因による過酸化水素濃度としては考えにく
い高濃度であるため、耐すきま腐食性評価には不適であ
るため判定□とした。In the case of evaluating the crevice corrosion resistance (Table 1), when the noble potential was +150 mV or more (based on the saturated KCl Ag / AgCl electrode), it was judged as "good". However, if the time required to reach the steady noble potential exceeds 24 hours, it is difficult to quickly reproduce the noble potential and it is not suitable for evaluation of crevice corrosion resistance. Further, under the condition of high concentration such that the concentration of hydrogen peroxide exceeds 30 mmol per 1 L, the cost burden of using hydrogen peroxide increases, and the concentration of hydrogen peroxide is a high concentration that is hardly considered as the concentration of hydrogen peroxide due to actual microorganisms. Therefore, it was unsuitable for evaluation of crevice corrosion resistance, so it was judged as □.
【００２５】貴化電位が+150mV（飽和KCl Ag/AgCl電極
基準）未満の場合は、耐すきま腐食性評価には不適であ
るため判定×とした。When the noble potential was less than +150 mV (based on a saturated KCl Ag / AgCl electrode), it was unsuitable for evaluation of crevice corrosion resistance, and was evaluated as x.
【００２６】耐孔食性および耐すきま腐食性を評価する
場合（表２）には、貴化電位が+470mV（飽和KCl Ag/AgC
l電極基準）以上となる場合に、判定○とした。ただ
し、過酸化水素濃度が１Ｌあたり30mmolを超えるような
高濃度の条件では、過酸化水素使用のコスト負担が増大
することと、実際の微生物原因による過酸化水素濃度と
しては考えにくい高濃度であるため、耐孔食性および耐
すきま腐食性評価には不適であるため判定□とした。When the pitting corrosion resistance and crevice corrosion resistance were evaluated (Table 2), the noble potential was +470 mV (saturated KCl Ag / AgC
When the value was equal to or more than (l electrode standard), it was judged as good. However, under high-concentration conditions in which the concentration of hydrogen peroxide exceeds 30 mmol per liter, the cost burden of using hydrogen peroxide increases, and the concentration of hydrogen peroxide is a high concentration that is hardly considered as a concentration of hydrogen peroxide due to actual microbial causes. Therefore, it was unsuitable for evaluation of pitting corrosion resistance and crevice corrosion resistance, and was therefore judged as □.
【００２７】貴化電位が+470mV（飽和KCl Ag/AgCl電極
基準）未満の場合は、耐孔食性および耐すきま腐食性評
価には不適であるため判定×とした。When the noble potential was less than +470 mV (based on a saturated KCl Ag / AgCl electrode), it was unsuitable for evaluating pitting corrosion resistance and crevice corrosion resistance.
【００２８】[0028]
【表１】 [Table 1]
【００２９】[0029]
【表２】 結果として過酸化水素濃度とpHを組み合わせて調整した
試験液にステンレス鋼を浸漬することにより、河川水や
海水で微生物作用により誘起されるような貴化電位に設
定して耐食性評価を実施可能であることがあきらかにな
った。[Table 2] As a result, by immersing stainless steel in a test solution adjusted by combining hydrogen peroxide concentration and pH, corrosion resistance can be evaluated by setting the noble potential as induced by microbial action in river water or sea water. Something became clear.
【００３０】[0030]
【発明の効果】以上の説明から明らかなように、本発明
で定めるpHおよび過酸化水素濃度条件を組み合わせた水
溶液を用いて、河川水や海水などで観察されるステンレ
ス鋼の貴化電位を考慮した耐食性を評価する試験液を調
製して、ステンレス鋼の耐食性を評価することが可能で
ある。As is apparent from the above description, the noble potential of stainless steel observed in river water or sea water is considered by using an aqueous solution combining the pH and hydrogen peroxide concentration conditions specified in the present invention. It is possible to evaluate the corrosion resistance of stainless steel by preparing a test solution for evaluating the corrosion resistance.
【００３１】したがって、本試験液を用いることは、微
生物腐食に対する材料選定や、新たな鋼材開発に有用で
ある。Therefore, the use of this test solution is useful for selecting materials for microbial corrosion and for developing new steel materials.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 紀平 寛 富津市新富20−１ 新日本製鐵株式会社技 術開発本部内 (72)発明者 三木 理 富津市新富20−１ 新日本製鐵株式会社技 術開発本部内 (72)発明者 加藤 敏朗 富津市新富20−１ 新日本製鐵株式会社技 術開発本部内 Ｆターム(参考） 2G050 AA01 BA01 BA20 CA01 DA01 EA06 EA10 EB03 4K062 BA14 BA20 CA03 CA05 CA10 DA01 DA10 EA20 FA02 FA04 FA16 GA10 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Kihira 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technology Development Division (72) Inventor Osamu Miki 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technology Development Division (72) Inventor Toshiro Kato 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technology Development Division F-term (reference) 2G050 AA01 BA01 BA20 CA01 DA01 EA06 EA10 EB03 4K062 BA14 BA20 CA03 CA05 CA10 DA01 DA10 EA20 FA02 FA04 FA16 GA10
Claims (4)
l 以下含有してpH3.0以上pH8.2以下であることを特徴と
するステンレス鋼の耐すきま腐食性の評価用試験液。Claims: 1. An amount of hydrogen peroxide of 1 mmol or more and 30 mmo per liter
l A test solution for evaluating crevice corrosion resistance of stainless steel, characterized by having a pH of not less than 3.0 and not more than pH 8.2.
（飽和KCl Ag/AgCl電極を参照電極とした電位値）以上
になるように、過酸化水素を1L あたり1 mmol以上30 mm
ol 以下とpH3.0以上pH3.9以下の範囲で調整したことを
特徴とするステンレス鋼の耐孔食性および耐すきま腐食
性の評価用試験液。2. The noble potential of immersed stainless steel is 470 mV.
(Potential value with saturated KCl Ag / AgCl electrode as reference electrode)
ol and a test solution for evaluating pitting corrosion resistance and crevice corrosion resistance of stainless steel, which are adjusted in the range of pH 3.0 to pH 3.9.
レス鋼を浸漬することによりステンレス鋼の耐食性を評
価する方法。3. A method for evaluating the corrosion resistance of stainless steel by immersing the stainless steel in the test solution according to claim 1.
じて過酸化水素濃度およびpHを調整することを特徴とす
る請求項３に記載のステンレス鋼の耐食性を評価する方
法。4. The method for evaluating corrosion resistance of stainless steel according to claim 3, wherein the hydrogen peroxide concentration and the pH are adjusted according to the target immersion potential of the stainless steel.
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Cited By (5)
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| JP2002318227A (en) * | 2001-02-16 | 2002-10-31 | Nkk Corp | Method for estimating life of surface treated steel material, surface treated steel material, method for designing surface treated steel material and method for manufacturing the same |
| JP2010197116A (en) * | 2009-02-24 | 2010-09-09 | Hitachi Plant Technologies Ltd | Method and apparatus for diagnosing pitting of stainless steel, and method and apparatus for diagnosing pitting of seawater pump using stainless steel as structural member |
| JP2010280947A (en) * | 2009-06-04 | 2010-12-16 | Kurimoto Ltd | Corrosion preventing method for stainless steel member |
| JP2013011564A (en) * | 2011-06-30 | 2013-01-17 | Ihi Corp | Corrosion fatigue test apparatus |
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| JP2010280947A (en) * | 2009-06-04 | 2010-12-16 | Kurimoto Ltd | Corrosion preventing method for stainless steel member |
| JP2013011564A (en) * | 2011-06-30 | 2013-01-17 | Ihi Corp | Corrosion fatigue test apparatus |
| CN113804613A (en) * | 2021-09-15 | 2021-12-17 | 鞍钢股份有限公司 | Test method for simulating corrosion of iron bacteria in water environment |
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