JPH0375338A - Martensitic stainless steel having excellent corrosion resistance and its manufacture - Google Patents
Martensitic stainless steel having excellent corrosion resistance and its manufactureInfo
- Publication number
- JPH0375338A JPH0375338A JP21104989A JP21104989A JPH0375338A JP H0375338 A JPH0375338 A JP H0375338A JP 21104989 A JP21104989 A JP 21104989A JP 21104989 A JP21104989 A JP 21104989A JP H0375338 A JPH0375338 A JP H0375338A
- Authority
- JP
- Japan
- Prior art keywords
- less
- stainless steel
- corrosion resistance
- martensitic stainless
- excellent corrosion
- 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.)
- Pending
Links
- 238000005260 corrosion Methods 0.000 title claims abstract description 88
- 230000007797 corrosion Effects 0.000 title claims abstract description 88
- 229910001105 martensitic stainless steel Inorganic materials 0.000 title claims abstract description 27
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 31
- 239000010959 steel Substances 0.000 claims abstract description 31
- 238000001816 cooling Methods 0.000 claims abstract description 26
- 238000005496 tempering Methods 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 4
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 8
- 229910052715 tantalum Inorganic materials 0.000 claims description 6
- 229910052726 zirconium Inorganic materials 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 229910052735 hafnium Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 abstract description 38
- 238000005336 cracking Methods 0.000 abstract description 32
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 abstract description 19
- 239000001569 carbon dioxide Substances 0.000 abstract description 19
- 229910002092 carbon dioxide Inorganic materials 0.000 abstract description 19
- 229910000037 hydrogen sulfide Inorganic materials 0.000 abstract description 19
- 229910000734 martensite Inorganic materials 0.000 abstract description 9
- 229910001220 stainless steel Inorganic materials 0.000 abstract description 8
- 239000010935 stainless steel Substances 0.000 abstract description 6
- 230000000694 effects Effects 0.000 description 15
- 239000000463 material Substances 0.000 description 7
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 229920006395 saturated elastomer Polymers 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 239000003112 inhibitor Substances 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 3
- 241000473391 Archosargus rhomboidalis Species 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 244000005894 Albizia lebbeck Species 0.000 description 1
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 241000581652 Hagenia abyssinica Species 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000001192 hot extrusion Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000007655 standard test method Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は耐食性の優れたマルテンサイト系ステンレス鋼
およびその製造方法に係り、さらに詳しくは例えば石油
・天然ガスの掘削、輸送及び貯蔵において湿潤炭酸ガス
や湿潤硫化水素を含む環境中で高い腐食抵抗および割れ
抵抗を有する高強度鋼とその製造方法に関する。Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a martensitic stainless steel with excellent corrosion resistance and a method for producing the same. This invention relates to a high-strength steel that has high corrosion resistance and cracking resistance in environments containing gas and wet hydrogen sulfide, and a method for producing the same.
（従来の技術）
近年生産される石油・天然ガス中には、湿潤な炭酸ガス
を多く含有する場合が増加している。こうした環境中で
炭素鋼や低合金鋼は著しく腐食することがよく知られて
いる。このため、掘削に使用される油井管や輸送に使用
されるラインパイプなどの防食対策として、腐食抑制剤
の添加が従来より行なわれてきた。しかし、腐食抑制剤
は高温ではその効果が失われる場合が多いことに加えて
。(Prior Art) Oil and natural gas produced in recent years increasingly contain a large amount of wet carbon dioxide. It is well known that carbon steel and low alloy steel corrode significantly in such environments. For this reason, corrosion inhibitors have traditionally been added to prevent corrosion of oil country tubular goods used for drilling, line pipes used for transportation, and the like. However, in addition to the fact that corrosion inhibitors often lose their effectiveness at high temperatures.
海洋油井や海底パイプラインでは腐食抑制剤の添加・回
収処理に要する費用は膨大なものとなり、適用できない
場合が多い。従って、腐食抑制剤を添加する必要のない
耐食材料に対するニーズが最近とみに高まっている。In offshore oil wells and undersea pipelines, the cost of adding and recovering corrosion inhibitors is enormous and is often not applicable. Therefore, the need for corrosion-resistant materials that do not require the addition of corrosion inhibitors has recently increased.
炭酸ガスを多く含む石油・天然ガス用の耐食材料として
は、耐食性の良好なステンレス鋼の適用かまず検討され
、例えばり、 Ｊ、クライン、コロ−ジョン ′８４
．ペーパーナンバー２１１にあるように、高強度で比較
的コストの安い鋼としてＡｌ５Ｉ４１０あるいは４２０
といった、１２〜１３％のＣｒを含有するマルテンサイ
ト系ステンレス鋼が広く使用され始めている。しかしな
がら、これらの鋼は湿潤炭酸ガス環境ではあっても高温
１例えば１２０ ’Ｃ以上の環境やＣＩ−イオン濃度の
高い環境では耐食性が充分ではなくなり、腐食速度が大
きいという難点を有する。さらにこれらの鋼は、石油・
天然ガス中に硫化水素が含まれている場合には著しく耐
食性が劣化し、全面腐食や局部腐食。As a corrosion-resistant material for petroleum and natural gas containing a large amount of carbon dioxide gas, the application of stainless steel with good corrosion resistance was first considered, for example, J. Klein, Corrosion '84.
．． As stated in paper number 211, Al5I410 or 420 is a high-strength and relatively low-cost steel.
Martensitic stainless steels containing 12 to 13% Cr are beginning to be widely used. However, these steels have the disadvantage that even in a humid carbon dioxide environment, their corrosion resistance is insufficient and their corrosion rate is high in an environment of high temperature 1, for example, 120'C or higher, or an environment with a high concentration of CI- ions. Furthermore, these steels are
When natural gas contains hydrogen sulfide, corrosion resistance deteriorates significantly, resulting in general or localized corrosion.
さらには応力腐食割れを生ずるという難点を有している
。このため上記のマルテンサイト系ステンレス鋼の使用
は、例えばＨ，Ｓ分圧がｏ、ｏｏｉ気圧といった極微量
のＨ７Ｓを含むか、あるいは全＜ ＨｚＳを含まない場
合に限られてきた。Furthermore, it has the disadvantage of causing stress corrosion cracking. For this reason, the use of the above-mentioned martensitic stainless steel has been limited to cases where, for example, the H, S partial pressure contains a trace amount of H7S such as o, ooi atmospheric pressure, or does not contain total < HzS.
これに対し、硫化水素による割れに対する抵抗を増した
マルテンサイト系ステンレス鋼として、例えば特開昭６
０−１７４８５９号公報、特開昭６２−５４０６３号公
報にみられる鯛が提案されている。しかし、これらの鋼
もＣＯ，環境での耐食性が必ずしも十分という訳ではな
かった。On the other hand, as martensitic stainless steel with increased resistance to cracking due to hydrogen sulfide, for example,
The sea bream seen in JP-A-0-174859 and JP-A-62-54063 has been proposed. However, these steels did not necessarily have sufficient corrosion resistance in a CO environment.
（発明が解決しようとする課題）
本発明はこうした現状に鑑み、高温や高ＣＩ−イオン濃
度の炭酸ガス環境でも十分な耐食性を有し、硫化水素を
含む場合においても高い割れ抵抗を有するマルテンサイ
ト系ステンレス鋼とその製造方法を提供することを目的
としている。(Problems to be Solved by the Invention) In view of the current situation, the present invention has been developed using martensite, which has sufficient corrosion resistance even in a carbon dioxide environment with high temperature and high CI-ion concentration, and has high cracking resistance even when containing hydrogen sulfide. The purpose is to provide stainless steels and their manufacturing methods.
（課題を解決するための手段）
本発明者らは、上記の目的を達成すべくマルテンサイト
系ステンレス鋼の成分を種々検討してきた結果、ついに
以下の知見を見出すに至った。(Means for Solving the Problem) The present inventors have studied various components of martensitic stainless steel in order to achieve the above object, and as a result, they have finally found the following knowledge.
まず、Ｃｒを１４％を超えて鋼に添加すると湿潤炭酸ガ
ス環境中における腐食速度が著しく小さくなり、かかる
鋼にＭｎを添加すると腐食速度は一段と小さくなること
を見出した。そしてこのＭｎの添加効果は、添加量を２
％を超えて添加すると顕著であることを見出した。また
、Ｍｎを２％を超えて添加した場合において、ＣＩを０
．０３％未満に低減すると湿潤炭酸ガス環境中における
耐食性がさらに改善され、２００℃以上にまで使用が可
能になることが分かった。一方、Ｍｎを２％を超えて添
加し、Ｃを０．０３％未満に低減させた鋼にＮを０．０
３％以上含有させると一段と高強度が得られることがわ
かった。このとき、かかる成分を有する綱は硫化水素を
含む環境においても高い割れ抵抗を有するという新知見
も得られた。First, it was discovered that when more than 14% Cr was added to steel, the corrosion rate in a wet carbon dioxide environment was significantly reduced, and when Mn was added to such steel, the corrosion rate was further reduced. The effect of adding Mn is as follows:
It has been found that the effect is significant when added in excess of %. In addition, when Mn is added in excess of 2%, CI is reduced to 0.
．． It has been found that when the corrosion resistance is reduced to less than 0.3%, corrosion resistance in a humid carbon dioxide environment is further improved, and use is possible up to 200°C or higher. On the other hand, 0.0% N was added to steel with Mn added exceeding 2% and C reduced to less than 0.03%.
It has been found that even higher strength can be obtained when the content is 3% or more. At this time, new findings were also obtained that steels containing such components have high cracking resistance even in environments containing hydrogen sulfide.
さらに本発明者らは検討をすすめ、Ｍｎを２％を超えて
添加し、Ｃを０．０３％未満に低減し、Ｎを０．０３％
以上添加した鋼中のＰを０．０２５％以下に低減し、Ｓ
を０．０１０％以下に低減するか、○を０、００４％以
下に低減するか、のいずれかを適用すると硫化水素を含
む環境における割れ抵抗が一段と改善されることを明ら
かにした。一方、これらの鯛にＣｕ、 Ｎｔ、 Ｍｏ、
Ｗを添加すれば高温あるいは高Ｃ１−イオン濃度の湿
潤炭酸ガス環境での腐食速度を一段と減少できることも
見出した。Furthermore, the present inventors conducted studies and added Mn in excess of 2%, reduced C to less than 0.03%, and added N to 0.03%.
The above added P in steel is reduced to 0.025% or less, and S
It has been revealed that the cracking resistance in an environment containing hydrogen sulfide is further improved by applying either of the following: reducing 0.010% or less, or reducing ○ to 0.004% or less. On the other hand, these sea bream were treated with Cu, Nt, Mo,
It has also been found that the addition of W can further reduce the corrosion rate in a humid carbon dioxide environment at high temperature or high C1- ion concentration.
本発明は上記の知見に基づいてなされたものであり、
第１発明の要旨とするところは、重量％で、Ｃｒ１４％
超１８％以下、Ｓｉ１％以下、Ｍｎ２％超７％以下、Ａ
１０．００５〜０．２％、ＮＯ，０３〜０．１５％を含
有し、Ｃを０．０３％未満に低減し、残部Ｆｅおよび不
可避不純物からなることを特徴とする耐食性の優れたマ
ルテンサイト系ステンレス鋼にあり、第２発明の要旨と
するところは、第１発明の鋼において、不可避不純物の
うち、重量％で、Ｐを０、０２５％以下、Ｓを０．０１
０％以下に低減したことを特徴とする耐食性の優れたマ
ルテンサイト系ステンレス鋼にあり、
第３発明の要旨とするところは、第１発明あるいは第２
発明の鋼において不可避不純物のうち、重量％で、０を
Ｏを０．００４％以下に低減したことを特徴とする耐食
性の優れたマルテンサイト系ステンレス鋼にあり、
第４発明の要旨とするところは、第１発明、第２発明あ
るいは第３発明の各綱において、重量％で、Ｃｕ１％以
下、Ｎｉ４％以下、Ｍｏ２％以下、Ｗ４％以下のうち１
種または２種以上を含有することを特徴とする耐食性の
優れたマルテンサイト系ステンレス鋼にあり、
第５発明の要旨とするところは、第１発明、第２発明、
第３発明あるいは第４発明の基調において、重量％で、
Ｔｉ０．２％以下、Ｚｒ０．２％以下、 ＮｂＯ，５％
以下、Ｖｏ、５％以下、Ｔａ０．２％以下、 Ｈｆ０．
２％以下のうち１種または２種以上を含有することを特
徴とする耐食性の優れたマルテンサイト系ステンレス鋼
にあり、
第６発明の要旨とするところは、第１発明、第２発明、
第３発明、第４発明あるいは第５発明の各綱において、
重量％で、Ｃａ０．００８％以下、希土類元素０．０２
％以下のうち１種または２種を含有することを特徴とす
る耐食性の優れたマルテンサイト系ステンレス鋼にあり
、
第７発明の要旨とするところは、第１発明、第２発明、
第３発明、第４発明、第５発明あるいは第６発明の基調
において、９００−１１００”Ｃでオーステナイト化し
た後、空冷以上の冷却速度で冷却し、次いで５６０℃以
上Ａ Ｃ１温度以下の温度で焼戻し処理を施した後、空
冷以上の冷却速度で冷却することを特徴とする耐食性の
優れたマルテンサイト系ステンレス鋼の製造方法にある
。The present invention has been made based on the above findings, and the gist of the first invention is that Cr14% by weight
More than 18%, Si 1% or less, Mn more than 2%, 7% or less, A
Martensite with excellent corrosion resistance, containing 10.005 to 0.2%, NO, 03 to 0.15%, C reduced to less than 0.03%, and the balance consisting of Fe and inevitable impurities. system stainless steel, and the gist of the second invention is that in the steel of the first invention, among the inevitable impurities, P is 0.025% or less and S is 0.01% by weight.
The third invention resides in a martensitic stainless steel with excellent corrosion resistance characterized by reduced corrosion resistance to 0% or less.
The fourth aspect of the invention resides in a martensitic stainless steel with excellent corrosion resistance, characterized in that among the inevitable impurities in the steel of the invention, 0 and O are reduced to 0.004% or less by weight. In each of the first, second, or third inventions, in weight%, 1% of Cu 1% or less, Ni 4% or less, Mo 2% or less, W 4% or less
The gist of the fifth invention resides in a martensitic stainless steel with excellent corrosion resistance characterized by containing one or more of the following: the first invention, the second invention,
In the keynote of the third invention or the fourth invention, in weight%,
Ti 0.2% or less, Zr 0.2% or less, NbO, 5%
Below, Vo: 5% or less, Ta: 0.2% or less, Hf: 0.
The sixth invention provides a martensitic stainless steel with excellent corrosion resistance characterized by containing one or more of 2% or less of the following: the first invention, the second invention,
In each of the third invention, fourth invention, or fifth invention,
In weight%, Ca 0.008% or less, rare earth elements 0.02
% or less, the martensitic stainless steel has excellent corrosion resistance, and the gist of the seventh invention is the first invention, the second invention,
In the keynote of the third invention, fourth invention, fifth invention, or sixth invention, after austenitizing at 900-1100"C, cooling at a cooling rate higher than air cooling, and then at a temperature of 560°C or higher and lower than A C1 temperature. The present invention provides a method for producing martensitic stainless steel having excellent corrosion resistance, which comprises cooling at a cooling rate higher than air cooling after tempering.
（作 用）
以下に本発明で成分および熱処理条件を限定した理由を
述べる。(Function) The reasons for limiting the components and heat treatment conditions in the present invention will be described below.
Ｃ：Ｃは多量に存在すると湿潤炭酸ガス環境における耐
食性を低下させ、硫化水素の存在する環境における応力
腐食割れ抵抗を減少させる。従って、Ｃを低減するとこ
れら特性の改善に効果があるが、Ｃ！ｉを０．０３％未
満とすれば特にその効果が著しく、０．０３％以上存在
する場合には耐食性を低下させることから、Ｃ量は０．
０３％未満に限定する。C: When present in a large amount, C reduces corrosion resistance in a wet carbon dioxide environment and reduces stress corrosion cracking resistance in an environment where hydrogen sulfide is present. Therefore, reducing C is effective in improving these characteristics, but C! If i is less than 0.03%, the effect is particularly remarkable, and if it is present at 0.03% or more, the corrosion resistance is reduced, so the amount of C is 0.03% or more.
Limited to less than 0.03%.
Ｓｉ ： Ｓｔは脱酸のために必要な元素であるが、１
％を超えて添加すると耐食性を著しく低下させることか
ら、上限含有量は１％とすべきである。Si: St is an element necessary for deoxidation, but 1
If added in excess of 1%, the corrosion resistance will be significantly reduced, so the upper limit content should be 1%.
Ｍｎ ： Ｍｎは脱酸および強度確保、さらには炭酸ガ
ス環境における耐食性向上のために有効な元素であるが
、含有量が２％以下ではその効果が不充分であり、７％
を超えて添加するとその効果は飽和するばかりか焼入れ
、焼戻し熱処理後にオーステナイトを生成する可能性が
あるので、含有量は２％超７％以下とする。Mn: Mn is an effective element for deoxidizing, ensuring strength, and improving corrosion resistance in a carbon dioxide environment, but its effect is insufficient if the content is less than 2%, and 7%
If more than 2% is added, the effect will not only be saturated, but also austenite may be formed after quenching and tempering heat treatment, so the content should be more than 2% and 7% or less.
Ｃｒ ： Ｃｒはマルテンサイト系ステンレス鋼を構成
する最も基本的かつ必須の元素であって耐食性を付与す
るために必要な元素であるが、含有量が１４％以下では
耐食性が十分ではなく、一方１８％を超えて添加すると
他の合金元素をいかに調整しても焼入れ後にマルテンサ
イト組織を得ることが困難となって強度確保が困難にな
るので上限含有量は１８％とすべきである。Cr: Cr is the most basic and essential element constituting martensitic stainless steel and is an element necessary to impart corrosion resistance, but if the content is less than 14%, corrosion resistance is insufficient; If it is added in excess of 18%, it will be difficult to obtain a martensitic structure after quenching and it will be difficult to ensure strength, no matter how the other alloying elements are adjusted. Therefore, the upper limit content should be 18%.
Ａ１： ／ＩＪは脱酸のために必要な元素であって含有
量が０．００５％未満ではその効果が充分ではなく、０
、２％を超えて添加すると粗大な酸化物系介在物が鋼中
に残留して硫化水素中での割れ抵抗を低下させるので、
含有量範囲は０．０ Ｏ５〜０．２％とする。A1: /IJ is an element necessary for deoxidation, and if the content is less than 0.005%, the effect is not sufficient, and 0.
If added in excess of 2%, coarse oxide inclusions will remain in the steel and reduce cracking resistance in hydrogen sulfide.
The content range is 0.0 O5 to 0.2%.
ＮＵＮはＣを低減したマルテンサイト系ステンレス鋼の
強度を上昇させる元素として有効であるが、０．０３％
未満ではその効果が十分ではなく、０．１５％を超える
とＣｒ窒化物を生成して耐食性を低下させ、また、割れ
抵抗をも低下させるので、含有量範囲は０．０３〜０．
１５％とする。NUN is effective as an element to increase the strength of martensitic stainless steel with reduced C content, but at 0.03%
If it is less than 0.15%, the effect will not be sufficient, and if it exceeds 0.15%, Cr nitrides will be produced, reducing corrosion resistance and cracking resistance, so the content range is from 0.03 to 0.
It shall be 15%.
以上が本発明における基本的成分であるが、本発明にお
いては必要に応じてさらに以下の元素を添加して特性を
一段と向上させることができる。The above are the basic components in the present invention, but in the present invention, the following elements can be further added as necessary to further improve the characteristics.
ＦＤＰは応力腐食割れ感受性を増加させる元素であるの
で少ないほうが好ましいが、あまりに少ないレベルにま
で低減させることは、いたずらにコストを上昇させるの
みで特性の改善効果は飽和するものであるから、本発明
の目的とする耐食性。Since FDP is an element that increases stress corrosion cracking susceptibility, it is preferable to reduce it to a low level, but reducing it to too low a level will only unnecessarily increase costs and the effect of improving properties will be saturated. The target corrosion resistance.
耐応力腐食割れ性を確保するのに必要十分なほど少ない
含有量として０．０２５％以下に低減すると耐応力腐食
割れ性が一段と改善される。When the content is reduced to 0.025% or less, which is sufficiently small to ensure stress corrosion cracking resistance, stress corrosion cracking resistance is further improved.
ＳＯ３はＰと同様に応力腐食割れ感受性を増加させる元
素であるので少ないほうが好ましいが、あまりに少ない
レベルにまで低減させることはいたずらにコストを上昇
させるのみで特性の改善効果は飽和するものであるから
、本発明の目的とする耐食性、耐応力腐食割れ性を確保
するのに必要十分なほど少ない含有量としてｏ、ｏｔｏ
％以下に低減すると耐応力腐食割れ性が一段と改善され
る。Like P, SO3 is an element that increases stress corrosion cracking susceptibility, so it is better to have less SO3, but reducing it to too low a level will only unnecessarily increase costs and the effect of improving properties will be saturated. , o, oto as a content as low as necessary and sufficient to ensure the corrosion resistance and stress corrosion cracking resistance targeted by the present invention.
% or less, stress corrosion cracking resistance is further improved.
Ｏ：Ｏは多量に存在すると粗大な酸化物系非金属介在物
クラスターを生成して応力腐食割れ感受性を増加させる
ので少ないほうが好ましいが、あまりに少ないレベルに
まで低減させることはいたずらにコストを上昇させるの
みで特性の改善効果は飽和するものであるから、本発明
の目的とする耐食性、耐応力腐食割れ性を一段と改善す
るのに必要十分なほど少ない含有量として０．００４％
以下に低減すると耐応力腐食割れ性が一段と改善される
。O: If O is present in a large amount, it will generate coarse oxide-based nonmetallic inclusion clusters and increase stress corrosion cracking susceptibility, so it is preferable to have a small amount, but reducing it to too low a level will unnecessarily increase costs. Since the property improvement effect is saturated with only 0.004%, the content is as low as necessary and sufficient to further improve the corrosion resistance and stress corrosion cracking resistance that are the objectives of the present invention.
When the stress corrosion cracking resistance is reduced to below, the stress corrosion cracking resistance is further improved.
Ｃｕ ： Ｃｕは２％超のＭｎと共存して湿潤炭酸ガス
環境の耐食性をさらに改善するのに効果があるが、１％
を超えて添加してもその効果は飽和するので上限含有量
は１％とする。Cu: Cu coexists with more than 2% Mn and is effective in further improving corrosion resistance in a wet carbon dioxide environment, but 1%
Since the effect will be saturated even if added in excess of 1%, the upper limit content is set at 1%.
Ｎｉ ： Ｎｉは湿潤炭酸ガス環境におけるマルテンサ
イト系ステンレス鋼の腐食速度を減少させ、硫化水素を
含む環境における割れ感受性を低下させる有用な元素で
あるが、４％を超えて添加してもその効果は飽和するの
で、４％以下の範囲に限定する。Ni: Ni is a useful element that reduces the corrosion rate of martensitic stainless steel in a humid carbon dioxide environment and reduces the cracking susceptibility in an environment containing hydrogen sulfide, but its effect is reduced even if it is added in an amount exceeding 4%. is saturated, so it is limited to a range of 4% or less.
Ｍｏ ： Ｍｏも２％超のＭｎと共存して湿潤炭酸ガス
環境の耐食性を改善するのに効果があるが、２％を超え
て添加してもその効果は飽和するばかりか、靭性なと他
の特性を低下させるようになるので上限含有量は２％と
する。Mo: Mo also coexists with more than 2% Mn and is effective in improving corrosion resistance in a humid carbon dioxide environment, but adding more than 2% not only saturates the effect, but also reduces toughness and other properties. The upper limit content is set at 2% because the properties of the element are deteriorated.
ＷＯＷも２％超のＭｎと共存して湿潤炭酸ガス環境の耐
食性を改善するのに効果があるが、４％を超えて添加し
てもその効果は飽和するばかりか、靭性なと他の特性を
低下させるようになるので上限含有量は４％とする。WOW is also effective in coexisting with more than 2% Mn to improve corrosion resistance in a wet carbon dioxide environment, but adding more than 4% not only saturates the effect, but also improves toughness and other properties. Therefore, the upper limit content is set at 4%.
Ｖ、 Ｔｉ、 Ｎｂ、 Ｔａ、 Ｚｒ、 Ｈｆ ： Ｖ
、 Ｔｉ、 Ｎｂ、 Ｔａ、 Ｚｒ。V, Ti, Nb, Ta, Zr, Hf: V
, Ti, Nb, Ta, Zr.
Ｈｆは耐食性を一段と向上させるのに有効な元素である
が、Ｔｉ、 Ｚｒ、 Ｔａ、 ）Ｉｆでは０．２％、Ｖ
、Ｎｂでは０．５％をそれぞれ超えて添加すると粗大な
析出物・介在物を生成して硫化水素含有環境における割
れ抵抗を低下させるようになるので上限含有量はＴｉ、
Ｚｒ、 Ｔａ、 Ｈｆでは０．２％、Ｖ、Ｎｂでは０
．５％とした。Hf is an effective element to further improve corrosion resistance, but in Ti, Zr, Ta, ) If, 0.2%, V
, Nb, if added in excess of 0.5% each, produces coarse precipitates and inclusions that reduce cracking resistance in an environment containing hydrogen sulfide, so the upper limit content is Ti, Nb,
0.2% for Zr, Ta, Hf, 0 for V, Nb
．． It was set at 5%.
Ｃａ、希土類元素：Ｃａおよび希土類元素（ＲＥＭ）は
熱間加工性の向上、耐食性の向上に効果のある元素であ
るが、Ｃａではｏ、 ｏ ｏ ｓ％を超えて、希土類元
素では０．０２％を超えて添加すると、それぞれ粗大な
非金属介在物を生成して逆に熱間加工性および耐食性を
劣化させるので、上限含有量はＣａでは０．００８％、
希土類元素では０．０２％とした。Ca and rare earth elements: Ca and rare earth elements (REM) are elements that are effective in improving hot workability and corrosion resistance, but for Ca it exceeds o, o o s%, and for rare earth elements it exceeds 0.02. If added in excess of 0.0%, coarse non-metallic inclusions will be formed and the hot workability and corrosion resistance will deteriorate, so the upper limit content is 0.008% for Ca;
For rare earth elements, it was set at 0.02%.
なお、本発明において希土類元素とは原子番号が５７〜
７１番および８９〜１０３番の元素およびＹを指す。In addition, in the present invention, rare earth elements have an atomic number of 57 to
Refers to elements 71 and 89 to 103 and Y.
上記の成分を有するステンレス鋼を熱処理してマルテン
サイト組織とし所定の強度を付与するに際し、オーステ
ナイト化温度を９００〜１１００℃としたのは、９００
℃より低い温度ではオーステナイト化が充分ではなく従
って必要な強度を得ることが困難だからであり、オース
テナイト化温度が１１００’Ｃを超えると結晶粒が著し
く粗大化して硫化水素含有環境における割れ抵抗が低下
するようになるので、オーステナイト化温度は９００〜
１１００℃とした。When heat-treating stainless steel having the above components to form a martensitic structure and imparting a predetermined strength, the austenitizing temperature was set to 900 to 1100°C.
This is because at temperatures lower than 1100'C, austenitization is not sufficient and it is therefore difficult to obtain the necessary strength.If the austenitization temperature exceeds 1100'C, the crystal grains become significantly coarsened and the cracking resistance in an environment containing hydrogen sulfide decreases. Therefore, the austenitizing temperature is 900~
The temperature was 1100°C.
オーステナイト化後の冷却における冷却速度を空冷以上
の冷却速度としたのは、空冷よりも遅い冷却速度ではマ
ルテンサイトが充分生成せず、所定の強度を確保するこ
とが困難になるからである。The reason why the cooling rate in cooling after austenitization is set to be higher than air cooling is because martensite is not sufficiently generated at a cooling rate slower than air cooling, making it difficult to secure a predetermined strength.
焼戻し温度を５６０℃以上Ａｃ、温度以下としたのは、
焼戻し温度が５６０℃未満では充分な焼戻しが行われず
、焼戻し温度がＡ ｃ １温度を超えると一部がオース
テナイト化しその後の冷却時にフレッシュ・マルテンサ
イトを生威し、いずれも充分に焼戻しされていないマル
テンサイトが残留するために硫化水素含有環境における
割れ感受性を増加させるためである。The reason why the tempering temperature was set to 560℃ or higher and lower than Ac,
If the tempering temperature is less than 560°C, sufficient tempering will not take place, and if the tempering temperature exceeds A c 1 temperature, part of the material will become austenite and produce fresh martensite during subsequent cooling, and neither will be sufficiently tempered. This is because residual martensite increases cracking susceptibility in an environment containing hydrogen sulfide.
焼戻し後の冷却における冷却速度を空冷以上の冷却速度
としたのは、空冷よりも遅い冷却速度では靭性が低下す
るためである。The reason why the cooling rate in cooling after tempering was set to be higher than air cooling is because toughness decreases at a cooling rate slower than air cooling.
本発明鋼は、通常の熱間圧延によって鋼板として使用す
ることが可能であるし、熱間押出あるいは熱間圧延によ
って鋼管として使用することも可能であるし、棒あるい
は線として使用することも勿論可能である。本発明鋼は
、油井管あるいはラインパイプとしての用途のほか、バ
ルブやポンプの部品としてなど多くの用途がある。The steel of the present invention can be used as a steel plate by ordinary hot rolling, can be used as a steel pipe by hot extrusion or hot rolling, and of course can be used as a bar or wire. It is possible. The steel of the present invention has many uses, such as as oil country tubular goods or line pipes, as well as parts for valves and pumps.
（実施例） 以下に本発明の実施例について説明する。(Example) Examples of the present invention will be described below.
第１表に示す成分のステンレス鋼を溶製し、熱間圧延に
よって厚さ１２ｍｍの鋼板とした後、第１表に併せて示
す条件で焼入れ焼戻し処理を施していずれも０．２％オ
フセット耐力が５６ｋｇ／−以上の高強度ステンレス鋼
とした。なお、第１表中の焼戻し温度はいずれも基調の
Ａｃ＋温度以下の温度である。次にこれらの鋼材から試
験片を採取して湿潤炭酸ガス環境における腐食試験、お
よび硫化水素含有環境における割れ試験（ＳＣＣ試験）
を行なった。湿潤炭酸ガス環境における腐食試験として
は、厚さ３ｍｍ、幅１５ａｍ、長さ５０１１ＩＩ１１の
試験片を用い、試験温度１５０℃および２００ ”Ｃの
オートクレーブ中で炭酸ガス分圧４０気圧の条件で１０
％ＮａＣ１水溶液中に３０日間浸漬して、試験前後の重
量変化から腐食速度を算出した。腐食速度の単位はｌｌ
１１１／ｙで表示したが、−船釣にある環境におけるあ
る材料の腐食速度が０．１ ｒｍ／ ｙ以下の場合、材
料は充分耐食的であり使用可能であると考えられている
。硫化水素含有環境における割れ試験としては、ＮＡＣ
Ｅ （米国腐食技術者協会）の定めている標準試験法で
あるＮＡＣＥ規格ＴＭ ０１７７に従って試験したが、
硫化水素分圧は０．１気圧、試験温度は１２０℃とした
。上記の条件で５％Ｎａ１Ｊ＋０．５％酢酸水溶液中に
セットした試験片に一定の単軸引張応力を負荷し、７２
０時間以内に破断するか否かを調べた。試験応力は各鋼
材の０．２％オフセット耐力の６０％の値とした。After melting stainless steel with the ingredients shown in Table 1 and hot rolling it into a steel plate with a thickness of 12 mm, it was quenched and tempered under the conditions shown in Table 1, resulting in a 0.2% offset yield strength. It was made of high-strength stainless steel with a weight of 56 kg/- or more. Note that all the tempering temperatures in Table 1 are below the basic Ac+ temperature. Next, test pieces were taken from these steel materials and subjected to a corrosion test in a humid carbon dioxide environment and a cracking test (SCC test) in an environment containing hydrogen sulfide.
I did this. For the corrosion test in a humid carbon dioxide environment, a test piece with a thickness of 3 mm, a width of 15 am, and a length of 5011II11 was used.
% NaCl aqueous solution for 30 days, and the corrosion rate was calculated from the weight change before and after the test. The unit of corrosion rate is l.
111/y, but - if the corrosion rate of a material in a boat fishing environment is less than 0.1 rm/y, the material is considered to be sufficiently corrosion resistant and usable. For cracking tests in environments containing hydrogen sulfide, NAC
Tested in accordance with NACE Standard TM 0177, a standard test method established by the American Society of Corrosion Engineers.
The hydrogen sulfide partial pressure was 0.1 atm, and the test temperature was 120°C. A constant uniaxial tensile stress was applied to the test piece set in 5% Na1J + 0.5% acetic acid aqueous solution under the above conditions.
It was investigated whether or not it would break within 0 hours. The test stress was set to a value of 60% of the 0.2% offset proof stress of each steel material.
試験結果を第１表に併せて示した。第１表のうち、腐食
試験結果において◎は腐食速度が０．０５ｍｍ／ｙ未満
、Ｏは腐食速度が０．０５１１１１／ｙ以上０、１０
ｍａ／ ｙ未満、×は腐食速度が０．１鴫／ｙ以上０．
５ ｍｍ／ ｙ未満、××は腐食速度が０．５ ｗ／
ｙ以上であったことをそれぞれ表わしており、割れ試験
結果において◎は破断しなかったもの、×は破断したも
のをそれぞれ表わしている。なお、第１表において、比
較鋼のＮα２９はＡｌ５Ｉ４２０鋼であり、ＮＣＬ３０
は９Ｃｒ ＩＭｏ綱であって、いずれも従来から湿潤
炭酸ガス環境で使用されている従来鋼である。The test results are also shown in Table 1. In Table 1, in the corrosion test results, ◎ means the corrosion rate is less than 0.05 mm/y, O means the corrosion rate is 0.051111/y or more 0, 10
Less than ma/y, × indicates corrosion rate of 0.1/y or more.
Less than 5 mm/y, XX indicates corrosion rate of 0.5 w/y
In the cracking test results, ◎ indicates that the crack was not broken, and × indicates that it was broken. In Table 1, the comparison steel Nα29 is Al5I420 steel, and NCL30
are 9Cr IMo steels, and both are conventional steels that have been conventionally used in humid carbon dioxide environments.
第１表から明らかなように本発明鋼である鋼弘１〜２８
は、湿潤炭酸ガス環境において２００ ’Ｃという従゛
来のマルテンサイト系ステンレス鋼では考えられないよ
うな高温で、かつ１０％ＮａＣ１というＣＩ−イオン濃
度が非常に高い環境であっても、実用的に使用可能な腐
食速度である０、 １ ｍｓ／ ｙよりも腐食速度が小
さく、かつ硫化水素含有環境における割れ試験において
も破断していないことから、優れた耐食性と耐応力腐食
割れ性を有していることがわかる。これに対して比較鋼
である鋼漱２９〜３４は湿潤炭酸ガス環境において１５
０℃でも既に腐食速度が０．１ ｎｍ／ ｙを大きく上
回っており、かつ硫化水素含有環境における割れ試験に
おいて破断している。As is clear from Table 1, Koko 1 to 28, which are the steels of the present invention,
is practical even at a high temperature of 200'C in a humid carbon dioxide environment, which is unimaginable for conventional martensitic stainless steel, and in an environment with a very high CI-ion concentration of 10% NaCl. The corrosion rate is lower than the corrosion rate of 0.1 ms/y, which is the corrosion rate that can be used for steel, and it did not break even in a cracking test in an environment containing hydrogen sulfide, so it has excellent corrosion resistance and stress corrosion cracking resistance. It can be seen that On the other hand, the comparison steels Koso 29 to 34 had 15
Even at 0°C, the corrosion rate was already well above 0.1 nm/y, and it fractured in a cracking test in an environment containing hydrogen sulfide.
（発明の効果）
以上述べたように、本発明は湿潤炭酸ガス環境における
優れた耐食性と湿潤硫化水素による割れに対して高い割
れ抵抗を有する鋼およびその製造方法を提供することを
可能としたものであり、産業の発展に貢献するところ極
めて大である。(Effects of the Invention) As described above, the present invention makes it possible to provide a steel having excellent corrosion resistance in a wet carbon dioxide environment and high cracking resistance against cracking caused by wet hydrogen sulfide, and a method for manufacturing the same. Therefore, it is extremely important to contribute to the development of industry.
Claims (7)
特徴とする耐食性の優れたマルテンサイト系ステンレス
鋼。(1) In terms of weight%, C is reduced to less than 0.03%, Si is 1% or less, Mn is more than 2% and 7% or less, Cr is more than 14% and 18% or less, Al 0.005 to 0.2%, N 0.03 to 0. A martensitic stainless steel with excellent corrosion resistance, characterized by containing .15% and the remainder consisting of Fe and unavoidable impurities.
れたマルテンサイト系ステンレス鋼。(2) The martensitic stainless steel with excellent corrosion resistance according to claim 1, characterized in that among the inevitable impurities, P is reduced to 0.025% or less and S is reduced to 0.010% or less.
食性の優れたマルテンサイト系ステンレス綱。(3) The martensitic stainless steel steel with excellent corrosion resistance according to claim 1 or 2, characterized in that among the inevitable impurities, O is reduced to 0.004% or less by weight.
請求項１、２または３記載の耐食性の優れたマルテンサ
イト系ステンレス鋼。(4) As an additional component, it contains one or more of Cu 1% or less, Ni 4% or less, Mo 2% or less, and W 4% or less in weight percent. Martensitic stainless steel with excellent corrosion resistance.
請求項１、２、３または４記載の耐食性の優れたマルテ
ンサイト系ステンレス鋼。(5) As an additional component, one of the following in weight%: V 0.5% or less, Ti 0.2% or less, Nb 0.5% or less, Zr 0.2% or less, Ta 0.2% or less, Hf 0.2% or less The martensitic stainless steel with excellent corrosion resistance according to claim 1, 2, 3, or 4, characterized in that it contains at least two or more kinds of martensitic stainless steel.
項１、２、３、４または５記載の耐食性の優れたマルテ
ンサイト系ステンレス鋼。(6) Claim 1, 2, 3, 4, or 5, characterized in that the additional component contains one or two of Ca0.008% or less and rare earth element 0.02% or less in weight percent. Martensitic stainless steel with excellent corrosion resistance.
ンサイト系ステンレス鋼を、９００〜１１００℃でオー
ステナイト化した後、空冷以上の冷却速度で冷却し、次
いで５６０℃以上Ａｃ＿１温度以下の温度で焼戻し処理
を施した後、空冷以上の冷却速度で冷却することを特徴
とする耐食性の優れたマルテンサイト系ステンレス鋼の
製造方法。(7) The martensitic stainless steel according to claim 1, 2, 3, 4, 5 or 6 is austenitized at 900 to 1100°C, then cooled at a cooling rate higher than air cooling, and then at Ac_1 temperature of 560°C or higher. A method for producing martensitic stainless steel with excellent corrosion resistance, which comprises tempering at a temperature below and then cooling at a cooling rate higher than air cooling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21104989A JPH0375338A (en) | 1989-08-16 | 1989-08-16 | Martensitic stainless steel having excellent corrosion resistance and its manufacture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21104989A JPH0375338A (en) | 1989-08-16 | 1989-08-16 | Martensitic stainless steel having excellent corrosion resistance and its manufacture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0375338A true JPH0375338A (en) | 1991-03-29 |
Family
ID=16599537
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21104989A Pending JPH0375338A (en) | 1989-08-16 | 1989-08-16 | Martensitic stainless steel having excellent corrosion resistance and its manufacture |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0375338A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07310143A (en) * | 1994-05-13 | 1995-11-28 | Sumitomo Metal Ind Ltd | Martensitic stainless steel |
| US6793744B1 (en) | 2000-11-15 | 2004-09-21 | Research Institute Of Industrial Science & Technology | Martenstic stainless steel having high mechanical strength and corrosion |
-
1989
- 1989-08-16 JP JP21104989A patent/JPH0375338A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07310143A (en) * | 1994-05-13 | 1995-11-28 | Sumitomo Metal Ind Ltd | Martensitic stainless steel |
| US6793744B1 (en) | 2000-11-15 | 2004-09-21 | Research Institute Of Industrial Science & Technology | Martenstic stainless steel having high mechanical strength and corrosion |
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