JPS5940230B2 - How to prevent stress corrosion cracking in stainless steel - Google Patents
How to prevent stress corrosion cracking in stainless steelInfo
- Publication number
- JPS5940230B2 JPS5940230B2 JP790780A JP790780A JPS5940230B2 JP S5940230 B2 JPS5940230 B2 JP S5940230B2 JP 790780 A JP790780 A JP 790780A JP 790780 A JP790780 A JP 790780A JP S5940230 B2 JPS5940230 B2 JP S5940230B2
- Authority
- JP
- Japan
- Prior art keywords
- stainless steel
- ions
- stress corrosion
- corrosion cracking
- prevent stress
- 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.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/18—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using inorganic inhibitors
- C23F11/185—Refractory metal-containing compounds
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【発明の詳細な説明】
本発明はステンレス鋼部材の応力腐食割れ防止方法に関
する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing stress corrosion cracking of stainless steel members.
ステンレス鋼は周知の通り、表面に酸化物保護皮膜であ
るいわゆる不動態皮膜を形成することにより良好な耐食
性を有しているため化学工業、海水利用装置等耐腐食性
を要する構造物の材料として広く利用されている。As is well known, stainless steel has good corrosion resistance due to the formation of a so-called passive film, which is an oxide protective film, on its surface, so it is used as a material for structures that require corrosion resistance, such as chemical industries and seawater utilization equipment. Widely used.
この場合、ステンレス鋼でも例えば高温の海水又は高濃
度の溶存酸素含有溶液等の環境下で長期間使用したとき
には、部材のある特定の個所に集中して前記保護皮膜が
破れて応力腐食割れを生じる欠点がある。即ち鋼表面に
おける活性態−不動態間の電池形成によるものである。
この局部腐食を防止するためには通常、鋼全体の合金組
成を変えて耐食性を向上させる方法がとられ、応力腐食
割れに対しては前記に加えて更にＣ量の低下あるいはＴ
ｉ、Ｎｂ等の安定化元素の添加が行われている。In this case, even when stainless steel is used for a long period of time in environments such as high-temperature seawater or high-concentration dissolved oxygen-containing solutions, stress corrosion cracking occurs because the protective film is broken in specific parts of the member. There are drawbacks. That is, this is due to the formation of a battery between active and passive states on the steel surface.
In order to prevent this local corrosion, a method is usually taken to improve the corrosion resistance by changing the alloy composition of the entire steel.
Stabilizing elements such as i and Nb are added.
この方法はステンレス鋼が既に高価の上に更に高価な合
金元素を増量する等のために極めて高価となり、経済的
に実用性に難点が生じる問題がある。本発明は上記欠点
を解決することを目的とするもので、例えば化学工業、
海水利用装置等のステンレス鋼部材の接合部又は溶接接
合の熱影響部に絶えず接する高温海水あるいは塩素イオ
ン５００ｐμｍ以上含有する腐食性のきびしい溶液中に
、腐食防止添加剤としてＭｏ０１−、ＷＯＩ−もしくは
Ｈ２ＶＯτイオンをＯ、Ｏｌｇイオン／ｌ以上添加し、
安価簡便にしかも長期安定して応力腐食割れを防止する
ようにした点を特徴とする。This method has the problem that stainless steel is already expensive, and it becomes extremely expensive due to the addition of more expensive alloying elements, making it economically impractical. The present invention aims to solve the above-mentioned drawbacks, for example, in the chemical industry,
Mo01-, WOI-, or H2VOτ is used as a corrosion-preventing additive in high-temperature seawater or highly corrosive solutions containing 500 pμm or more of chlorine ions, which are constantly in contact with the joints of stainless steel members in seawater utilization equipment or the heat-affected zones of welded joints. Adding ions at O, Olg ions/l or more,
It is characterized by being inexpensive, simple, and stable over a long period of time to prevent stress corrosion cracking.
ここで、前記各イオンはＮａ２Ｍｏ０４、Ｎａ２Ｗ０４
３ＮａＶ０３、に２Ｍ００４、に２Ｗ０４、ＫＶ０３等
の可溶のアルカリ塩で添加される。Here, each of the ions is Na2Mo04, Na2W04
It is added as a soluble alkali salt such as 3NaV03, 2M004, 2W04, KV03, etc.
なおＮａＶ０３、ＫＶＯ３は液中でＨ２ＶＯ４″イオン
となるが、溶液の状態によつて更にＶ０３″、Ｈ３ＶＯ
ｉ、ＨＶＯＩ一を生じることがある。従つて本明細書に
おいてはＨ２ＶＯ４″をもつてこれらすべてのイオンを
代表させるものとする。以下本発明を詳細に説明する。Note that NaV03 and KVO3 become H2VO4'' ions in the solution, but depending on the state of the solution, they can further become V03'' and H3VO
i, HVOI may occur. Therefore, in this specification, H2VO4'' is used to represent all of these ions.The present invention will be explained in detail below.
本発明者等はステンレス鋼の応力腐食割れを防止する合
金元素として効果の著るしいＭ。The present inventors discovered M, which is highly effective as an alloying element for preventing stress corrosion cracking in stainless steel.
，Ｗ，に着目して、それらの塩水、高濃度の溶存酸素含
有高温溶液等の腐食環境下での応力腐食割れ防止機構に
ついて詳しく調査研究した結果、ＭＯ，Ｗ，Ｖはそれぞ
れＭＯＯＩ−，ＷＯＩ−，Ｈ２ＶＯｌイオンとして溶液
中に溶出して、腐食の加速要因である塩素イオン等の応
力腐食個所への侵入又は同個所での濃縮を妨げると共に
、応力腐食個所の鋼表面の再不動態化を促進して、応力
腐食割れが防止されることを知見した。そこで化学工業
あるいは海水利用装置等においてステンレス鋼部材の接
合部又は溶接接合の熱影響部等の応力腐食割れ発生個所
に絶えず接する海水あるいは塩素イオンを５００ＰＰＩ
！以上含有する腐食性のきびしい溶液中に腐食防止用添
加剤として所要量のＭＯＯＩ−，ＷＯＩ−もしくはＨ２
Ｏ４−イオンを添加することによつて、前記応力腐食発
生個所のみに集中してＭＯＯｌ−，ＷＯ了−もしくはＨ
２ＶＯ４−イオンの濃度を高めて接することができ、ス
テンレス鋼部材全体の合金組成の高級化によつて耐食性
を高める従来方法に比較してＭＯ，Ｗ，Ｖの総添加量が
大巾に節減され安価に局部腐食防止の効果が得られる。, W, and investigated and researched the mechanism for preventing stress corrosion cracking in corrosive environments such as salt water and high-temperature solutions containing high concentrations of dissolved oxygen. -, H2VOl ions are eluted into the solution, preventing chlorine ions, etc., which are factors that accelerate corrosion, from entering or concentrating at stress corrosion locations, and promoting repassivation of the steel surface at stress corrosion locations. It was discovered that stress corrosion cracking can be prevented. Therefore, in the chemical industry or seawater utilization equipment, etc., seawater or chlorine ions that are constantly in contact with stress corrosion cracking areas such as joints of stainless steel parts or heat-affected zones of welded joints are treated at 500 PPI.
! The required amount of MOOI-, WOI- or H2 as a corrosion-inhibiting additive in the severely corrosive solution containing the above
By adding O4- ions, MOOl-, WO- or H
The total amount of MO, W, and V added can be greatly reduced compared to the conventional method of increasing the corrosion resistance by increasing the concentration of 2VO4- ions and increasing the alloy composition of the entire stainless steel member. Local corrosion prevention effect can be obtained at low cost.
本発明において、ステンレス鋼部材の接合部又は溶接接
合の熱影響部に絶えず接する海水あるいは塩素イオンを
５００鼎以上含有する腐食性のきびしい溶液中に添加す
るＭＯＯ？−，ＷＯＩ−もしくはＨ２ＶＯ４−イオンの
量を０．０１ｇイオン／ｌ以上に限定したのは、０．０
１ｇイオン／ｌ未満ではステンレス鋼部材の接合部又は
溶接接合の熱影響部のＭＯＯｌ−，ＷＯＩ−もしくはＨ
２ＶＯ７イオンによる再不動態化の効果が十分に得られ
ないためである。In the present invention, MOO? -, WOI- or H2VO4- ions are limited to 0.01 g ions/l or more.
If it is less than 1 g ion/l, MOOl-, WOI- or H of the joint of stainless steel parts or the heat affected zone of welded joint
This is because the effect of repassivation by 2VO7 ions cannot be sufficiently obtained.
実施例
試験材として第２図に示す如くＵ字形に曲げた長さ７５
×巾１０×厚さ２詣の、６５０℃３時間空冷の熱処理（
溶接接合の熱影響部に相当する熱処理）を施したＳＵＳ
３Ｏ４の試験片５，６を重ねてステンレスボルトナツト
７で結合密着したダブルＵベント試験材を２５０℃、溶
存酸素８ＰＦ１、Ｃｌ−イオン１０００ＰＰＩ［ｌを含
む３１オートクレーブルＵベンド試験材を使用した。As an example test material, length 75 was bent into a U-shape as shown in Fig. 2.
x Width 10 x Thickness 2 mm, air-cooled at 650℃ for 3 hours (
SUS subjected to heat treatment (corresponding to the heat affected zone of welded joints)
A 31 autoclave U-bend test material containing 8PF1 dissolved oxygen and 1000 PPI [l] of Cl- ions was used as a double U-bent test material in which 3O4 test pieces 5 and 6 were stacked and tightly connected with stainless steel bolt nuts 7 at 250°C.
前記試験材を２５０℃、溶存酸素８ＰＰＩ［Ｌ，ＣＺ−
イオノ１０００ｐｐＩｎを含む３１オートクレーブ中の
溶液に５００時間浸漬せしめ、前記溶液中にＭＯＯ了−
，ＷＯＩ−もしくはＨ２ＶＯ４−イオンをそれぞれ濃度
０〜１ｇイオン／！の路囲で種々に変えて添加し、浸漬
後の応力腐食割れの有無を調査した。いて光学顕微鏡を
用いて計測した最大割れ深さにより行い、最大割れ深さ
と添加イオン濃度の関係を第１図に示した。The test material was heated at 250°C with 8 PPI of dissolved oxygen [L, CZ-
Iono was immersed in a solution in a 31 autoclave containing 1000 ppIn for 500 hours.
, WOI- or H2VO4- ions at a concentration of 0 to 1 g ions/! The presence or absence of stress corrosion cracking after immersion was investigated by adding various amounts to the road walls. Figure 1 shows the relationship between the maximum crack depth and the added ion concentration.
第１図では縦軸に最大割れ深さ（５）を、横軸に添加イ
オン濃度（ｇイ芽ン／ｌ）をとり、ＭＯＯＸ−イオンに
ついての最大割れ深さと添加イオン濃度の関係を一○一
、Ｈ２ＶＯＺイオンについての同関係を・・・・・・△
・・・・・・、ＷＯＩ−イオンについての同関係をーー
ロ−にて示している。In Figure 1, the vertical axis represents the maximum crack depth (5), and the horizontal axis represents the added ion concentration (g germ/l), and the relationship between the maximum crack depth and the added ion concentration for MOOX- ions is plotted by 1. The same relationship regarding H2VOZ ions...△
. . . The same relationship for WOI- ion is shown by -lo-.
同図に見る通り、ＭＯＯ了−，Ｈ２Ｏ７ラＷＯＩ−の各
イオンのいずれにおいても、イオン濃度が０．０１ｇイ
オン／ｌ以上で最大割れ深さが２５μ以下となり、本発
明が耐応力腐食割れ性を著しく向上する効果のあること
を示した。As shown in the figure, for both MOO- and H2O7- and WOI- ions, when the ion concentration is 0.01 g ions/l or more, the maximum crack depth is 25 μ or less, and the stress corrosion cracking resistance of the present invention is It was shown that it is effective in significantly improving the
第１図は最大割れ深さと添加イオン濃度との関係を示し
た図表、第２図は応力腐食割れ試験材の形状を示した正
面図である。
５，６・・・・・・試験片、７・・・・・・ステンレス
ボルトナツト。FIG. 1 is a chart showing the relationship between maximum crack depth and added ion concentration, and FIG. 2 is a front view showing the shape of the stress corrosion cracking test material. 5, 6... Test piece, 7... Stainless steel bolt nut.
Claims (1)
に絶えず接する海水あるいは塩素イオンを５００ｐｐｍ
以上含有する腐食性のきびしい溶液中に、腐食防止用添
加剤としてＭｏＯ＾２＿４＾−、Ｗ＾２＿４＾−もしく
はＨ＿２ＶＯ＿４＾−イオンを０．０１ｇイオン／ｌ以
上添加することを特徴とするステンレス鋼の応力腐食割
れ防止方法。1 Contains 500 ppm of seawater or chlorine ions that are constantly in contact with the joints of stainless steel parts or the heat-affected zone of welded joints.
A stainless steel characterized by adding 0.01 g ion/l or more of MoO^2_4^-, W^2_4^-, or H_2VO_4^- ions as a corrosion-inhibiting additive to the above-mentioned severely corrosive solution. Method for preventing stress corrosion cracking.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP790780A JPS5940230B2 (en) | 1980-01-25 | 1980-01-25 | How to prevent stress corrosion cracking in stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP790780A JPS5940230B2 (en) | 1980-01-25 | 1980-01-25 | How to prevent stress corrosion cracking in stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS56119783A JPS56119783A (en) | 1981-09-19 |
| JPS5940230B2 true JPS5940230B2 (en) | 1984-09-28 |
Family
ID=11678619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP790780A Expired JPS5940230B2 (en) | 1980-01-25 | 1980-01-25 | How to prevent stress corrosion cracking in stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5940230B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10021915C2 (en) * | 2000-05-05 | 2003-04-24 | Henkel Kgaa | Inhibition of pitting and crevice corrosion |
| JP7409916B2 (en) * | 2020-03-13 | 2024-01-09 | 三菱重工業株式会社 | Method for evaluating stress corrosion cracking in steam turbines |
-
1980
- 1980-01-25 JP JP790780A patent/JPS5940230B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56119783A (en) | 1981-09-19 |
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