JP2003130788A - Method for estimating corrosion rate of steel product - Google Patents
Method for estimating corrosion rate of steel productInfo
- Publication number
- JP2003130788A JP2003130788A JP2001324607A JP2001324607A JP2003130788A JP 2003130788 A JP2003130788 A JP 2003130788A JP 2001324607 A JP2001324607 A JP 2001324607A JP 2001324607 A JP2001324607 A JP 2001324607A JP 2003130788 A JP2003130788 A JP 2003130788A
- Authority
- JP
- Japan
- Prior art keywords
- rust
- corrosion rate
- steel
- corrosion
- amount
- 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.)
- Granted
Links
Landscapes
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
Abstract
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、鋼材、特に好適に
は耐候性鋼材の腐食速度の推定に関し、大気環境下での
鋼材の腐食速度を高精度に推定可能とするものである。
なお、以下では、本発明に適用する鋼材として耐候性鋼
材を例示して説明するが、 本発明が鋼材一般に適用でき
るものであることは言うまでもない。
【０００２】
【従来の技術】耐候性鋼は、鋼中にＰ、Cu、Cr、Ni等の
合金元素を添加し大気中における耐食性を向上させた鋼
であり、タンク、鉄塔、橋梁等の鋼構造物に広く使用さ
れている。耐候性鋼は、屋外の大気暴露下において数年
で、腐食の原因である酸素や水を通しにくい保護性さび
と呼ばれるさび層を形成し、その後の腐食の進行を抑制
している。このため、耐候性鋼は防錆塗料の塗布が不要
であり、いわゆる裸使用が可能で安価な高耐食材料であ
る。
【０００３】耐候性鋼材を使用した鋼構造物は、ライフ
サイクルコストやミニマムメンテナンスの観点から注目
されているが、適用するには各種の制限があり、また適
用後も最低限の維持管理、点検が必要である。例えば、
建設省（現国土交通省）による耐候性鋼の適用指針
（「耐候性鋼材の橋梁への適用に関する共同研究報告書
（ＸＸ）、建設省土木研究所、（社）鋼材倶楽部、
（社）日本橋梁建設協会発行」）によれば、飛来塩分量
が0.05mdd （mg／dm2 ／day ）以上となる地域では、従
来の耐候性鋼（JISG3144：溶接構造用耐候性熱間圧延鋼
材) は無塗装で使用できないことが規定されている。
【０００４】飛来塩分量の測定は長期間を要するが、一
般に、飛来塩分量は海岸からの距離とともに減少するの
で、各沿岸地域に応じて、飛来塩分量の測定を省略して
もよい離岸距離が定められている。しかし、海からの飛
来塩分が少ない山間部でも、路面に凍結防止のため融雪
塩を散布する場合があり、 そのような環境下では、耐候
性鋼材に著しい腐食を生じ、保護性さびが形成されない
場合もある。また、常に湿った環境下では保護性さびは
形成されにくいことが知られており、場合によっては適
切な処置を必要とする場合もある。
【０００５】耐候性鋼を使用した鋼構造物の維持管理上
最も重要なことは、鋼材表面に保護性さびが形成された
かどうかを判定することである。ここで、「（耐候性）
鋼材がさび安定化状態にあること」の定義は、例えば、
「社団法人腐食防食協会主催、第132 回腐食防食シンポ
ジウム資料（2001）、pp27〜36（特にp30 参照）」によ
れば、「構造物耐荷重性能の経年劣化が工学的に問題と
ならない程度に腐食速度が低減( 目安として0.01mm／ｙ
以下) した状態になること」と示されている。
【０００６】しかしながら、耐候性鋼に保護性さびが形
成されて腐食速度が低減する期間は、耐候性鋼の大気中
での暴露環境に大きく依存するのが現実であり、その判
定方法として的確で信頼性のあるさび安定化状態評価方
法は未だ確立されていないのが現状である。ここで、本
質的に重要となるのは、問題とする鋼材の大気環境下に
おける腐食速度である。腐食速度は、腐食量の微分値で
あり、腐食量の経年変化を測定し、その腐食量カーブか
ら回帰式により算出される。
【０００７】つまり、ある時点での腐食速度を測定する
ためには、初めに多くの試験片を暴露し、一定期間ごと
にそれらの試験片を順次回収して当該試験片の初期重量
からの腐食による重量減を求めた過去の一連のデータが
必要となる。しかしながら、このようなデータを採取す
ることは、 鋼構造物の維持管理のための手段としてはコ
ストも労力もかかり、とても簡便な方法とは言えない。
確かに、 この方法は、 鋼構造物が架設された時点からそ
の構造物と同じ環境に測定用試料（試験片）を設置し、
その腐食量を追跡することのできる確実で信頼性の高い
方法である。
【０００８】そのため、従来から、 腐食速度と相関があ
ると考えられているさびの状態を判定し、 腐食速度を簡
便に推定する各種の方法が提案されている。まず、さび
の外観からの判定基準として、「耐候性鋼材の橋梁への
適用に関する共同研究報告書（ＸＶ）（建設省土木研究
所、（社）鋼材倶楽部、（社）日本橋梁建設協会発
行）」に示されている５段階評価基準がある。この基準
は、 さび外観の粗度、剥離さびの有無から評点をつけて
評価するものである。 すなわち、外観上で、繊密で密着
性のあるさびが形成されていれば、腐食速度は十分低減
されているものと判定し、維持管理上問題がないとする
ものである。
【０００９】次に、 現場で非破壊かつ迅速にさび状態を
計測する方法として、「Corrosion、vol.45、No.4、pp3
47-352(1989) 」には、「錆層のイオン透過抵抗を測定
して、錆の保護性を評価する方法」が開示されている。
この方法は、さび層の環境遮断性に着目したものであ
り、定量的な方法で優れている。また、特開平11-31620
9 号公報には、耐候性鋼材と参照電極との電位差を測定
して、その電位差から腐食速度を推定する方法が開示さ
れている。
【００１０】さらに、特開2000-241339 号公報には、さ
び層の断面の光学顕微鏡解析を行って、さび層内のクラ
ック密度、あるいは、地鉄界面における消光錆占有率に
よってさびの保護性を判定する方法が開示されている。
【００１１】
【発明が解決しようとする課題】しかしながら、上記の
５段階評価基準によるさびの外観判定については、観察
者の主観がはいることになり、一般性に欠け、定量的な
評価が困難であるという問題がある。また、さび層のイ
オン透過抵抗を測定する方法は、定量性があり優れた方
法といえるが、異常腐食を生じた厚いさびの場合、イオ
ン透過抵抗の測定結果に信頼性がなく、外観判定を併用
せざるを得ず、やはり一般性に欠ける。
【００１２】なお、イオン透過抵抗の測定は、実際の腐
食速度を測定するものではなく、さびの環境遮断性と腐
食速度の相関を仮定して測定する方式である。また、特
開平11-316209 号公報に開示された、電位差を測定する
方法は、さびで覆われた鋼板の電位と腐食速度との相関
について原理的に不明な点が多く、厚い異常さびで覆わ
れた場合には測定値に誤差を生ずるという欠点を有す
る。
【００１３】さらに、特開2000-241339 号公報に開示さ
れた、さび層の断面の光学顕微鏡写真を解析する方法で
は、その解析のための指標として提示されているクラッ
ク密度と界面消光錆占有率と腐食速度との定量的相関が
必ずしも明確にされていない。また、自然にできたさび
層の不均一性を考えると、ミクロ的な観察結果での判定
では誤差が大きいものと考えられる。
【００１４】本発明は、 以上に示した各問題点を解消
し、 簡便かつ定量的な鋼材の腐食速度推定方法を提供す
るものである。なお、腐食速度を推定することができれ
ば、その推定した腐食速度に基づいて腐食評価を行うこ
とが容易であることは、既に説明したとおりである。
【００１５】
【発明が解決しようとする課題】本発明は、大気環境で
暴露された耐候性鋼材に代表される鋼材の腐食速度を高
精度に推定することを可能としたものである。すなわ
ち、 本発明は、 大気環境下に曝された鋼材の腐食速度推
定方法であって、該鋼材の暴露期間と、 該鋼材に形成さ
れたさび層に蓄積された塩分量とから腐食速度を推定す
ることを特徴とする鋼材の腐食速度推定方法によって上
記課題を解決したのである。
【００１６】
【発明の実施の形態】鋼材の腐食は環境に大きく依存す
るが、既に説明したように、特に飛来塩分量と相関を持
つことが知られている。そして、本発明者らは、 単に腐
食量と飛来塩分量の相関だけにとどまらず、腐食速度と
飛来塩分量の間にも強い相関をもつことを見出し、 本発
明をするに至ったのである。
【００１７】ところで、飛来塩分量は、季節さらには年
毎の変動が大きく、その測定には長期間を要する。さら
に、ある橋梁を考えた場合、その橋梁全体に対する飛来
塩分量は同じだとしても、内桁・外桁、あるいは、フラ
ンジ・ウエブ、上面（対空面）・下面（対地面) で、塩
分の付着の仕方が異なってくることは容易に想像でき
る。そして、付着、蓄積の仕方が異なってくれば、腐食
の仕方も当然に異なってくる。
【００１８】ここで、鋼材の腐食に影響を及ぼすのは、
実効的には飛来した塩分そのものではなく、鋼材表面の
さび層に実際に付着し蓄積した塩分の量、すなわち、さ
び中蓄積塩分量である。一方で、耐候性鋼は経時ととも
に、さび状態が変化し、保護性を増す性質を持ってい
る。したがって、さび中蓄積塩分量が同じだとしても、
短期間暴露された耐候性鋼と長期間暴露された耐候性鋼
では、その腐食速度は異なっている。
【００１９】以上の知見に基づき、 本発明者らは、耐候
性鋼の腐食速度が、さび中蓄積塩分量と暴露期間に依存
することを見出した。また、 以上の知見に基づき、 鋼材
の暴露期間およびさび中蓄積塩分量と、その腐食速度と
の関係を更に明確にするため、大気環境に暴露された耐
候性鋼についての調査を実施した。
【００２０】まず、さび中蓄積塩分量の算出測定方法に
ついて説明する。暴露期間が既知の耐候性鋼材のさび層
を地鉄が露出するまで採取し、採取した総さび重量を電
子天秤で計測する。更に、採取したさびのうちの一定量
（約 200mg程度) について、Cl濃度分析を実施する。そ
して、 そのCl濃度分析値から、下記（１）式に基づき、
さび中蓄積塩分量を導出する。
【００２１】
さび中蓄積塩分量（mg・NaCl／100cm2：md) ＝ 採取した総さび重量(mg) ×
Cl濃度（％）×（NaClモル濃度（ｇ）／Clモル濃度（ｇ））×
100 ／採取面積（cm2 ） ・・・ （１）
一方、 腐食速度は、上述のように、腐食による重量減か
ら腐食量の経年変化を測定して、その腐食量カーブから
回帰式（Ｙ＝ａＸb 、Ｙ：腐食量、Ｘ：暴露期間、 a、
b ：係数）を算出し、時間微分することで求められる
（ｄY ／ｄＸ＝ａｂＸb-1 ）。
【００２２】図１のグラフに、 以上の手順に基づいて求
めた暴露期間毎のさび中蓄積塩分量と腐食速度の関係を
示す。図２は、 図１の結果に基づき、 腐食速度をパラメ
―タとして、鋼材の暴露期間とさび中蓄積塩分量の関係
を再構成して示したグラフである。すなわち、このよう
に、一度、図２のデータを採取しておけば、その後は、
図２を適用することで、上記のさび中蓄積塩分量と暴露
期間のデータから、 腐食速度を簡便かつ高精度に推定す
ることが可能となる。
【００２３】さらに、既に説明したさび安定化状態の判
定基準に基づき、腐食速度が0.01mm／ｙ以下であるかど
うかを判定することで、 簡単にさび安定化状態の評価を
実施することができる。ところで、本発明の鋼材の腐食
速度推定方法を適用して、実際の鋼構造物の腐食評価を
行うには、 評価対象の鋼構造物そのもののさびを採取す
る代わりに、鋼構造物が竣工した時点で、 その鋼構造物
と同一素材の評価試験片を構造物の近傍に装着し、同一
条件の環境下で大気暴露しておくようにしておき、その
評価試験片を適用することもできる。
【００２４】この場合、所要年数経過後の腐食評価時
に、 当該評価試験片を取り外して所定面積のさび層を削
り取り、 その塩分量の測定を行い、 測定した塩分量と経
過年数、すなわち、暴露期間とから、腐食速度推定を行
う。 このようにして推定した腐食速度から、さびの保護
性を容易に判定することができ、鋼構造物の的確な腐食
評価を行うことが可能となる。
【００２５】ちなみに、測定後の評価試験片は再利用す
ることが可能である。すなわち、当該評価試験片を、取
付けていた元の場所に再度取付けておけば、次の腐食評
価時に、未だ削り取っていない部分のさび層を削り取っ
て塩分量を測定することで、その時点での腐食速度推定
を行うことができる。 そのため、本発明では、 評価試験
片を用いる場合においても多数の評価試験片を用意して
おく必要がなく、 必要最小限の評価試験片を用意するだ
けで足りる。
【００２６】
【実施例】耐候性鋼を、種々の環境に暴露し、所定の暴
露期間経過後にその試験片を回収し、本発明方法に従
い、さび中蓄積塩分量から推定腐食速度を求めた。その
結果を表１に示す。なお、表１には、比較のため、各試
験片について、 その重量減少量から実測腐食速度を求め
た結果を示した。
【００２７】
【表１】
【００２８】また、図３は、 表１に示す各地点での結果
を図２のデータ上にオーバープロットしたグラフであ
る。以上のことから、 本発明によって得た推定腐食速度
と実測腐食速度とが良い一致を示していることは明らか
である。
【００２９】
【発明の効果】本発明によれば、環境変化によるさび状
態の変化を的確に評価することが可能となり、 耐候性鋼
材に代表される鋼材の腐食速度を簡便かつ高精度に推定
することができるようになった。さらには、さび安定化
の判定も容易に実現できる。すなわち、本発明を適用す
ることで、 耐候性鋼等の鋼材を用いた鋼構造物の維持管
理を、簡便、かつ、的確に行うことができるようにな
り、もしも腐食速度の増大が見られた場合には、早急に
塗装等の適切な補修を行うことで、構造物としての致命
的な損傷を回避することが可能となる。Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for estimating the corrosion rate of a steel material, particularly preferably a weatherable steel material. It can be estimated.
In the following, a description will be given by exemplifying a weather-resistant steel material as a steel material applied to the present invention. However, it is needless to say that the present invention can be generally applied to steel materials. 2. Description of the Related Art Weather-resistant steel is a steel in which alloying elements such as P, Cu, Cr, and Ni are added to steel to improve corrosion resistance in the atmosphere, and is used for steels for tanks, steel towers, bridges, and the like. Widely used for structures. Weather resistant steel forms a rust layer, called a protective rust, which is hard to penetrate oxygen and water, which cause corrosion, in several years under outdoor atmospheric exposure, and suppresses the progress of the subsequent corrosion. For this reason, the weather-resistant steel does not require the application of a rust-preventive paint, and is a so-called bare use and inexpensive highly corrosion-resistant material. [0003] Steel structures using weather-resistant steel are attracting attention from the viewpoint of life cycle cost and minimum maintenance. However, there are various restrictions on application, and even after application, minimum maintenance and inspection are required. is necessary. For example,
Guidelines for the application of weathering steel by the Ministry of Construction (currently the Ministry of Land, Infrastructure, Transport and Tourism) (“Joint research report on application of weathering steel to bridges (XX), Ministry of Construction, Public Works Research Institute, Steel Club,
According to (published by the Japan Bridge Construction Association), in areas where the amount of incoming salt is 0.05 mdd (mg / dm 2 / day) or more, conventional weather-resistant steel (JISG3144: weather-resistant hot rolling for welded structures) It is stipulated that steel materials cannot be used without painting. Although the measurement of the amount of incoming salt takes a long time, the amount of incoming salt generally decreases with the distance from the coast, so that the measurement of the amount of incoming salt may be omitted depending on each coastal area. The distance is defined. However, snow-melting salt may be sprayed on the road surface to prevent freezing, even in mountainous areas where the amount of salt coming from the sea is low, and in such an environment, the weather-resistant steel material will be significantly corroded and no protective rust will be formed. In some cases. Further, it is known that protective rust is hard to be formed in a constantly moist environment, and in some cases, appropriate treatment is required. [0005] The most important thing in maintaining a steel structure using weathering steel is to determine whether or not protective rust has formed on the surface of the steel material. Here, "(weather resistance)
The definition of `` the steel is in a rust-stabilized state '' is, for example,
According to the 132nd Corrosion and Corrosion Symposium (2001), pp. 27-36 (especially see p. 30) sponsored by the Association of Corrosion and Corrosion Prevention, pp. 27-36 (in particular, see p30). Reduced corrosion rate (0.01mm / y as a guide)
Below). However, the period during which the protective rust is formed on the weather-resistant steel and the corrosion rate is reduced actually depends greatly on the environment in which the weather-resistant steel is exposed to the air. At present, a reliable rust stabilization state evaluation method has not been established yet. Here, what is essentially important is the corrosion rate of the steel in question in an atmospheric environment. The corrosion rate is a differential value of the amount of corrosion, and is obtained by measuring the secular change of the amount of corrosion and calculating the regression equation from the corrosion amount curve. That is, in order to measure the corrosion rate at a certain point, many test specimens are first exposed, and the test specimens are sequentially collected at regular intervals to obtain corrosion from the initial weight of the test specimen. A series of past data for weight loss due to is required. However, collecting such data is expensive and labor-intensive as a means of maintaining steel structures, and is not a very simple method.
Certainly, in this method, after the steel structure is erected, the measurement sample (specimen) is set in the same environment as the steel structure,
It is a reliable and reliable way to track the amount of corrosion. For this reason, various methods have conventionally been proposed for determining the state of rust, which is considered to be correlated with the corrosion rate, and for simply estimating the corrosion rate. First, as a criterion based on the appearance of rust, "Joint Research Report on Application of Weathering Steel to Bridges (XV) (published by Public Works Research Institute, Ministry of Construction, Steel Club, and Japan Bridge Construction Association) There are five-level evaluation criteria shown in "." This criterion is evaluated by giving a score based on the roughness of the rust appearance and the presence or absence of peeling rust. That is, if a rust having a fine and adherent appearance is formed, it is determined that the corrosion rate is sufficiently reduced, and there is no problem in maintenance. Next, as a method for nondestructively and quickly measuring the rust state on site, "Corrosion, vol. 45, No. 4, pp3
47-352 (1989) "discloses a" method of measuring the ion permeation resistance of a rust layer to evaluate rust protection ".
This method focuses on the environmental barrier properties of the rust layer, and is excellent in a quantitative method. Also, JP-A-11-31620
No. 9 discloses a method of measuring a potential difference between a weather-resistant steel material and a reference electrode and estimating a corrosion rate from the potential difference. [0010] Further, Japanese Patent Application Laid-Open No. 2000-241339 discloses that the cross-section of the rust layer is analyzed by an optical microscope, and the protection of the rust is determined by the crack density in the rust layer or the quenching rust occupancy at the ground iron interface. A method for determining is disclosed. [0011] However, the judgment of the appearance of the rust based on the above-mentioned five-grade evaluation standard is subject to the observer's subjectivity, lacks generality, and is difficult to quantitatively evaluate. There is a problem that is. The method of measuring the ion transmission resistance of the rust layer is quantitative and excellent, but in the case of thick rust with abnormal corrosion, the measurement results of the ion transmission resistance are not reliable, and the appearance judgment must be made. It has to be used together and lacks generality. The measurement of the ion permeation resistance is not a method of measuring an actual corrosion rate, but a method of assuming a correlation between the environmental barrier property of rust and the corrosion rate. In addition, the method for measuring the potential difference disclosed in Japanese Patent Application Laid-Open No. H11-316209 has many points in principle about the correlation between the potential of a rust-covered steel sheet and the corrosion rate, and the method of covering with a thick abnormal rust. This has the drawback of causing errors in the measured values. Furthermore, in the method disclosed in Japanese Patent Application Laid-Open No. 2000-241339 for analyzing an optical micrograph of a cross section of a rust layer, crack density and interface quenching rust occupancy presented as indices for the analysis are disclosed. The quantitative correlation between corrosion rate and corrosion rate is not always clear. Considering the non-uniformity of the naturally formed rust layer, it is considered that there is a large error in the judgment based on the microscopic observation result. The present invention solves the above-mentioned problems and provides a simple and quantitative method for estimating the corrosion rate of steel. As described above, if the corrosion rate can be estimated, the corrosion evaluation can be easily performed based on the estimated corrosion rate. SUMMARY OF THE INVENTION The present invention makes it possible to estimate with high accuracy the corrosion rate of a steel material represented by a weather-resistant steel material exposed in an atmospheric environment. That is, the present invention is a method for estimating a corrosion rate of a steel material exposed to an atmospheric environment, and estimates a corrosion rate from an exposure period of the steel material and an amount of salt accumulated in a rust layer formed on the steel material. The above problem was solved by a method for estimating the corrosion rate of a steel material, which is characterized in that: BEST MODE FOR CARRYING OUT THE INVENTION Corrosion of steel material greatly depends on the environment, but as described above, it is known that there is a correlation particularly with the amount of flying salt. The present inventors have found that there is not only a correlation between the amount of corrosion and the amount of flying salt but also a strong correlation between the corrosion rate and the amount of flying salt, and have led to the present invention. The amount of incoming salt fluctuates greatly from season to season and from year to year, and its measurement requires a long period of time. Furthermore, when considering a certain bridge, even if the amount of incoming salt for the entire bridge is the same, salt adhesion on the inner girder / outer girder or on the flange / web, upper surface (air surface) / lower surface (ground surface) It is easy to imagine that the way of doing things will be different. And if the way of adhesion and accumulation is different, the way of corrosion will naturally be different. Here, the influence on the corrosion of the steel material is as follows.
Effectively, it is not the amount of salt itself that has come, but the amount of salt that actually adheres and accumulates on the rust layer on the surface of the steel material, that is, the amount of salt accumulated in the rust. On the other hand, the weathering steel has a property that the rust state changes with time and the protection property is increased. Therefore, even if the amount of accumulated salt in rust is the same,
The corrosion rates of short-term and weather-exposed weathering steels are different. Based on the above findings, the present inventors have found that the corrosion rate of weathering steel depends on the amount of salt accumulated in rust and the exposure period. In addition, based on the above findings, a survey was conducted on weathering steel exposed to the atmospheric environment in order to further clarify the relationship between the exposure period of steel and the amount of accumulated salt in rust and its corrosion rate. First, a method for calculating and measuring the amount of accumulated salt in rust will be described. A rust layer of a weather-resistant steel material with a known exposure period is collected until the ground iron is exposed, and the total rust weight collected is measured with an electronic balance. Furthermore, a Cl concentration analysis is performed on a certain amount (about 200 mg) of the collected rust. Then, based on the Cl concentration analysis value, based on the following equation (1),
The amount of accumulated salt in rust is derived. Amount of salt accumulated in rust (mg · NaCl / 100 cm 2 : md) = total rust weight (mg) × Cl concentration (%) × (NaCl molar concentration (g) / Cl molar concentration (g)) × 100 / Sampling area (cm 2 ) (1) On the other hand, as described above, the corrosion rate is obtained by measuring the secular change of the amount of corrosion from the weight loss due to corrosion and calculating the regression equation (Y = aX b , Y: amount of corrosion, X: exposure period, a,
b: coefficient) and time-differentiated (dY / dX = abX b-1 ). FIG. 1 is a graph showing the relationship between the amount of salt accumulated in the rust and the corrosion rate for each exposure period obtained based on the above procedure. FIG. 2 is a graph reconstructing the relationship between the exposure period of steel and the amount of salt accumulated in rust, based on the results of FIG. 1 and using the corrosion rate as a parameter. That is, once the data of FIG. 2 has been collected as described above,
By applying FIG. 2, it is possible to easily and accurately estimate the corrosion rate from the data on the amount of accumulated salt in rust and the exposure period. Further, it is possible to easily evaluate the rust-stabilized state by determining whether the corrosion rate is 0.01 mm / y or less based on the rust-stabilized state criterion already described. . By the way, in order to evaluate the corrosion rate of an actual steel structure by applying the method for estimating corrosion rate of steel material of the present invention, instead of collecting the rust of the steel structure itself to be evaluated, the steel structure was completed. At this point, an evaluation test piece of the same material as the steel structure can be mounted near the structure, exposed to the atmosphere under the same conditions, and the evaluation test piece can be applied. In this case, at the time of the corrosion evaluation after the required number of years, the test piece is removed, a rust layer of a predetermined area is scraped off, the salt content is measured, and the measured salt content and elapsed years, ie, the exposure period Then, the corrosion rate is estimated. Rust protection can be easily determined from the estimated corrosion rate in this manner, and accurate corrosion evaluation of a steel structure can be performed. Incidentally, the evaluation test piece after the measurement can be reused. That is, if the evaluation test piece is attached again to the original place where it was attached, at the time of the next corrosion evaluation, the rust layer of the portion that has not yet been removed is scraped off, and the salt content is measured. Corrosion rate estimation can be performed. Therefore, in the present invention, even when using the evaluation test pieces, it is not necessary to prepare a large number of evaluation test pieces, and it is sufficient to prepare the minimum necessary evaluation test pieces. EXAMPLE A weathering steel was exposed to various environments, a test piece was recovered after a predetermined exposure period, and an estimated corrosion rate was determined from the amount of accumulated salt in rust according to the method of the present invention. Table 1 shows the results. For comparison, Table 1 shows the results of determining the measured corrosion rate from the weight loss of each test piece. [Table 1] FIG. 3 is a graph in which the results at each point shown in Table 1 are overplotted on the data of FIG. From the above, it is clear that the estimated corrosion rate obtained by the present invention and the actually measured corrosion rate show good agreement. According to the present invention, it is possible to accurately evaluate a change in rust state due to an environmental change, and to easily and accurately estimate a corrosion rate of a steel material represented by a weather-resistant steel material. Now you can do it. Further, the determination of rust stabilization can be easily realized. That is, by applying the present invention, the maintenance and management of a steel structure using a steel material such as a weather-resistant steel can be performed easily and accurately, and an increase in the corrosion rate was observed. In such a case, by performing appropriate repairs such as painting immediately, it is possible to avoid fatal damage as a structure.
【図面の簡単な説明】
【図１】暴露期間をパラメ―タとして、さび中蓄積塩分
量と腐食速度の関係を示すグラフである。
【図２】腐食速度をパラメ―タとして、耐候性鋼材の暴
露期間とさび中蓄積塩分量の関係を示すグラフである。
【図３】図２のグラフに、 各地域に置いた耐候性鋼材試
験片から得られた結果をプロットしたグラフである。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the amount of accumulated salt in rust and the corrosion rate, with the exposure period as a parameter. FIG. 2 is a graph showing the relationship between the exposure period of weathering steel and the amount of salt accumulated in rust, with the corrosion rate as a parameter. FIG. 3 is a graph obtained by plotting the results obtained from weathering steel test pieces placed in each region on the graph of FIG.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 星野 俊幸 岡山県倉敷市水島川崎通１丁目（番地な し） 川崎製鉄株式会社水島製鉄所内 Ｆターム(参考） 2G050 AA01 BA02 BA05 CA01 EB01 EB10 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshiyuki Hoshino 1-chome, Mizushima-Kawasaki-dori, Kurashiki City, Okayama Prefecture ） Kawasaki Steel Corporation Mizushima Works F-term (reference) 2G050 AA01 BA02 BA05 CA01 EB01 EB10
Claims (1)
定方法であって、該鋼材の暴露期間と、 該鋼材に形成さ
れたさび層に蓄積された塩分量とから腐食速度を推定す
ることを特徴とする鋼材の腐食速度推定方法。Claims: 1. A method for estimating a corrosion rate of a steel material exposed to an atmospheric environment, comprising: an exposure period of the steel material; a salt content accumulated in a rust layer formed on the steel material; A method for estimating a corrosion rate of a steel material, comprising estimating a corrosion rate from steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001324607A JP3731524B2 (en) | 2001-10-23 | 2001-10-23 | Method for estimating corrosion rate of steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001324607A JP3731524B2 (en) | 2001-10-23 | 2001-10-23 | Method for estimating corrosion rate of steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2003130788A true JP2003130788A (en) | 2003-05-08 |
| JP3731524B2 JP3731524B2 (en) | 2006-01-05 |
Family
ID=19141306
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001324607A Expired - Fee Related JP3731524B2 (en) | 2001-10-23 | 2001-10-23 | Method for estimating corrosion rate of steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3731524B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100487422C (en) * | 2004-12-17 | 2009-05-13 | 中国科学院金属研究所 | Accelerated test method for atmospheric corrosion and special test device therefor |
| JP2011112445A (en) * | 2009-11-25 | 2011-06-09 | Kobe Steel Ltd | Method for estimating thickness reduction quantity of steel material |
| CN104568638A (en) * | 2013-10-10 | 2015-04-29 | 鞍钢股份有限公司 | Method and device for testing binding performance of rusty layer with steel sample and substrate |
| JP2017040470A (en) * | 2015-08-17 | 2017-02-23 | 東京電力ホールディングス株式会社 | Corrosive environment evaluation method and device |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103411875A (en) * | 2013-07-26 | 2013-11-27 | 攀钢集团攀枝花钢铁研究院有限公司 | Quantitative measurement method for surface corrosion rate of film coated steel plate |
-
2001
- 2001-10-23 JP JP2001324607A patent/JP3731524B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100487422C (en) * | 2004-12-17 | 2009-05-13 | 中国科学院金属研究所 | Accelerated test method for atmospheric corrosion and special test device therefor |
| JP2011112445A (en) * | 2009-11-25 | 2011-06-09 | Kobe Steel Ltd | Method for estimating thickness reduction quantity of steel material |
| CN104568638A (en) * | 2013-10-10 | 2015-04-29 | 鞍钢股份有限公司 | Method and device for testing binding performance of rusty layer with steel sample and substrate |
| CN104568638B (en) * | 2013-10-10 | 2017-08-11 | 鞍钢股份有限公司 | Method and device for testing binding performance of rusty layer with steel sample and substrate |
| JP2017040470A (en) * | 2015-08-17 | 2017-02-23 | 東京電力ホールディングス株式会社 | Corrosive environment evaluation method and device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3731524B2 (en) | 2006-01-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Morcillo et al. | Atmospheric corrosion of weathering steels. Overview for engineers. Part II: Testing, inspection, maintenance | |
| Sohanghpurwala | Manual on service life of corrosion-damaged reinforced concrete bridge superstructure elements | |
| Barnes et al. | Ground-penetrating radar for network-level concrete deck repair management | |
| Jia et al. | Incipient corrosion behavior and mechanical properties of low-alloy steel in simulated industrial atmosphere | |
| JP2007263923A (en) | Method for diagnosing deterioration due to corrosion of wiring fitting for power transmission | |
| JP6213859B2 (en) | Estimating the average remaining thickness by estimating the average corrosion depth of the ground corrosion damage zone | |
| Lau et al. | Corrosion of epoxy-coated rebar in marine bridges—Part 2: Corrosion in cracked concrete | |
| JP2003130788A (en) | Method for estimating corrosion rate of steel product | |
| JP2007039970A (en) | Predicting method for rusting level of non-painted atmospheric corrosion-resistant steel bridge | |
| Kubzova et al. | Influence of chloride deposition on corrosion products | |
| Crampton et al. | Assessment of weathering steel bridge performance in Iowa and development of inspection and maintenance techniques. | |
| Lawler et al. | Condition survey of older west Virginia bridge decks constructed with epoxy-coated reinforcing bars | |
| JP2011227005A (en) | Method for testing corrosion acceleration of heavy corrosion protection coated steel material | |
| Clemeña | Investigation of the resistance of several new metallic reinforcing bars to chloride-induced corrosion in concrete | |
| JP3797189B2 (en) | Method for estimating corrosion rate and evaluation method for steel | |
| JP2000001816A (en) | Decision method of applicability to bridge of weather- resistant steel | |
| Koteš et al. | Rapid tests of corrosion in corrosion chamber | |
| Granata et al. | Assessing corrosion on steel structures using corrosion coulometer | |
| Ha et al. | Monitoring for relative effect of corrosive environmental factor on corrosion rate for steel structural details | |
| Klinghoffer et al. | Smart Structures: Embeddable sensors for use in the integrated monitoring systems of concrete structures | |
| Saraswathy et al. | Performance of galvanized and stainless steel rebars in concrete under macrocell corrosion conditions | |
| WINT | Performance of Weathering Steel Bridge under Atmospheric Corrosion in Myanmar | |
| Thandar et al. | Atmospheric corrosion of weathering steel in Myanmar and its correlation on accelerated test | |
| JP7020448B2 (en) | Method for estimating the amount of flying salt and method for determining the applicability of weathering steel | |
| THANDAR et al. | The Effect of Substrate's Preparation on Repainting Degradation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20041021 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050914 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20050920 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20051003 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091021 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101021 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101021 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111021 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111021 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121021 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121021 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131021 Year of fee payment: 8 |
|
| LAPS | Cancellation because of no payment of annual fees |