JP2000319761A - Austenitic stainless steel excellent in molten salt corrosion resistance in chloride environment - Google Patents
Austenitic stainless steel excellent in molten salt corrosion resistance in chloride environmentInfo
- Publication number
- JP2000319761A JP2000319761A JP11125678A JP12567899A JP2000319761A JP 2000319761 A JP2000319761 A JP 2000319761A JP 11125678 A JP11125678 A JP 11125678A JP 12567899 A JP12567899 A JP 12567899A JP 2000319761 A JP2000319761 A JP 2000319761A
- Authority
- JP
- Japan
- Prior art keywords
- less
- molten salt
- corrosion
- stainless steel
- salt 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.)
- Withdrawn
Links
- 238000005260 corrosion Methods 0.000 title claims abstract description 68
- 230000007797 corrosion Effects 0.000 title claims abstract description 68
- 150000003839 salts Chemical class 0.000 title claims abstract description 42
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 title claims abstract description 17
- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims abstract description 7
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 7
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- 229910000831 Steel Inorganic materials 0.000 abstract description 20
- 239000010959 steel Substances 0.000 abstract description 20
- 229910052759 nickel Inorganic materials 0.000 abstract description 4
- 239000010813 municipal solid waste Substances 0.000 abstract description 3
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 3
- 230000002829 reductive effect Effects 0.000 abstract description 3
- 229910052750 molybdenum Inorganic materials 0.000 abstract description 2
- 229910052748 manganese Inorganic materials 0.000 abstract 1
- 229910052698 phosphorus Inorganic materials 0.000 abstract 1
- 229910045601 alloy Inorganic materials 0.000 description 15
- 239000000956 alloy Substances 0.000 description 15
- 229910001220 stainless steel Inorganic materials 0.000 description 11
- 239000010935 stainless steel Substances 0.000 description 11
- 230000000694 effects Effects 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000002485 combustion reaction Methods 0.000 description 6
- 230000004580 weight loss Effects 0.000 description 6
- 239000002699 waste material Substances 0.000 description 5
- 238000005275 alloying Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 239000002440 industrial waste Substances 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 150000003568 thioethers Chemical class 0.000 description 3
- 229910052726 zirconium Inorganic materials 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000003628 erosive effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000003546 flue gas Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000001012 protector Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910052702 rhenium Inorganic materials 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、例えば廃棄物焼却
炉のボイラーチューブやプロテクタ材など、塩化物を含
む溶融塩腐食環境において優れた耐溶融塩腐食特性を有
するオーステナイト系ステンレス鋼に関する。The present invention relates to an austenitic stainless steel having excellent resistance to molten salt corrosion in a chloride-containing molten salt corrosion environment, such as a boiler tube and a protector material of a waste incinerator.
【０００２】[0002]
【従来の技術】近年、環境意識の高揚およびエネルギー
資源の確保という点から、都市ごみや産業廃棄物の焼却
処理設備への関心が高まっている。2. Description of the Related Art In recent years, there has been an increasing interest in facilities for incinerating municipal waste and industrial waste from the viewpoints of raising environmental awareness and securing energy resources.
【０００３】焼却処理設備は一般に、燃焼設備、排ガス
冷却設備、排ガス浄化設備および煙突を備え、これらの
設備は各種ダクトや配管で結ばれている。また、大型の
焼却炉の中にはボイラーを設置し、燃焼排ガスと熱交換
を行うことで、廃熱をエネルギーとして活用している設
備も数多くある。焼却設備は、ダイオキシンを発生させ
ないため、燃焼部は８００℃以上で２秒以上滞留させる
必要がある。そのため排ガスダクト、ボイラー、熱交換
器等の排ガス冷却設備では、排ガスの温度が常時４００
〜８００℃程度になる。しかも都市ごみや産業廃棄物を
燃焼するとＣｌを多量に含んだ高温の燃焼灰や排ガスが
発生するため、ボイラーチューブ、熱交換器等では特に
Ｃｌを含む溶融塩により激しく腐食される。従来、これ
らのボイラーチューブ、熱交換器においては、腐食の厳
しい部位にＮｉ基合金、マイルドな部位にＳＵＳ３１０
Ｓ等の耐熱ステンレス鋼を使用している。[0003] Incineration facilities generally include a combustion facility, an exhaust gas cooling facility, an exhaust gas purification facility, and a chimney, and these facilities are connected by various ducts and pipes. In addition, many large incinerators have boilers installed and exchange heat with flue gas to utilize waste heat as energy. Since the incinerator does not generate dioxin, it is necessary to keep the combustion section at 800 ° C. or more for 2 seconds or more. Therefore, in exhaust gas cooling facilities such as exhaust gas ducts, boilers and heat exchangers,
８００800 ° C. Moreover, burning municipal solid waste and industrial waste generates high-temperature combustion ash and exhaust gas containing a large amount of Cl, so that boiler tubes, heat exchangers, and the like are particularly strongly corroded by molten salts containing Cl. Conventionally, in these boiler tubes and heat exchangers, a Ni-based alloy is used in a severely corroded portion, and a SUS310 is used in a mildly corroded portion.
Heat resistant stainless steel such as S is used.
【０００４】[0004]
【発明が解決しようとする課題】前述の耐熱ステンレス
鋼を使用する場合、高温腐食性に問題が残る。家庭ごみ
や産業廃棄物は塩化物を多量に含んでおり、燃焼環境に
おいて溶融塩が生成したり、熱分解によって塩化水素ガ
スを発生したりすることによって焼却炉体およびその付
帯設備は厳しい腐食環境に曝されるからである。つま
り、廃棄物の燃焼環境は、高温の塩化物や塩化水素ガス
による激しい高温腐食を受ける点で、一般的な燃料（重
油、軽油、ガソリン、天然ガス等）の燃焼環境や電気ヒ
ーターによる高温酸化を主体とする環境とは著しく異な
る。When the above-mentioned heat-resistant stainless steel is used, a problem remains in hot corrosion. Household garbage and industrial wastes contain a large amount of chlorides, and the incinerator body and its ancillary facilities are subject to severe corrosive environments due to the formation of molten salts in the combustion environment and the generation of hydrogen chloride gas by thermal decomposition. Because it is exposed to In other words, the combustion environment of waste is subject to severe high-temperature corrosion due to high-temperature chloride and hydrogen chloride gas, and the combustion environment of general fuels (heavy oil, light oil, gasoline, natural gas, etc.) and high-temperature oxidation by electric heaters It is significantly different from an environment mainly based on
【０００５】このような環境における材料の高温腐食特
性は、近年、精力的に検討されており、例えば、特開平
８−１２０３９２号には、過去の例と詳細に対比しなが
ら廃棄物発電ボイラの加熱器管用に適する成分範囲が開
示されている。過去に開示された例を含めて、塩化部環
境下の高温腐食に及ぼす合金元素の作用および成分設計
の動向を整理すると以下のようになる。 １．Ｃｒ塩化物の揮発を防ぐためにＣｒを低くすること
があるが、一般的にはＣｒとＮｉの含有量は多い傾向に
あり、相バランスの点からＭｏも添加される。 ２．鋼中のＣが悪影響を及ぼすことから、Ｃの低減に加
え、Ｎｂ、Ｔｉ、Ｚｒ、Ｖなどの炭化物形成元素の添加
や、Ｂ、Ｚｒなどの粒界偏析元素を添加する。 ３．表層に安定な酸化皮膜を形成させるために、Ａｌ、
Ｓｉ、希土類元素などを添加する。 このように、塩化物環境下の耐溶融塩腐食性に優れた材
料の成分設計は、主に高温腐食特性に対して有効な元素
を添加することに主眼が置かれていることがわかる。そ
の結果、耐高温腐食特性に優れた合金は、多くの合金元
素を含有するＦｅ基合金およびＮｉ基合金(いずれもＦ
ｅ含有量が５０質量％以下)となっている。[0005] The high-temperature corrosion characteristics of materials in such an environment have been energetically studied in recent years. For example, Japanese Patent Application Laid-Open No. H8-120392 discloses a waste power boiler in comparison with past examples. Suitable component ranges for heater tubes are disclosed. Including the examples disclosed in the past, the effects of alloying elements on high-temperature corrosion in a chloride-part environment and trends in component design are summarized as follows. 1. Although Cr may be lowered to prevent the volatilization of Cr chloride, the contents of Cr and Ni generally tend to be large, and Mo is also added from the viewpoint of phase balance. 2. Since C in the steel has an adverse effect, in addition to the reduction of C, addition of carbide forming elements such as Nb, Ti, Zr, and V, and addition of grain boundary segregation elements such as B and Zr. 3. In order to form a stable oxide film on the surface layer, Al,
Si, a rare earth element or the like is added. Thus, it can be seen that the component design of a material having excellent resistance to molten salt corrosion in a chloride environment mainly focuses on adding an element effective for high-temperature corrosion characteristics. As a result, alloys having excellent high-temperature corrosion resistance are Fe-based alloys and Ni-based alloys (both of which are
e content is 50% by mass or less).
【０００６】しかしながら、上述した元素の添加は、素
材費の高コスト化につながる。また、高合金化すること
によって、製造性が悪くなる傾向にあり、製造コストの
上昇も招いている。一方、４００〜７００℃の温度範囲
では、Ｃｌによる溶融塩腐食を生じさせるため、ＮＣＦ
６２５クラスのＮｉ基合金やＳＵＳ３１０Ｓクラスのス
テンレス鋼でも急激に腐食することがある。このような
高価な材料を数カ月で取り替える必要が生じた場合に
は、焼却炉プラントのランニングコストの上昇につなが
る。[0006] However, the addition of the above-mentioned elements leads to an increase in material costs. In addition, due to the high alloying, the manufacturability tends to deteriorate, and the manufacturing cost is increased. On the other hand, in a temperature range of 400 to 700 ° C., molten salt corrosion by Cl
Even a 625-class Ni-based alloy or a SUS310S-class stainless steel may rapidly corrode. If it becomes necessary to replace such expensive materials in a few months, this will increase the running costs of the incinerator plant.
【０００７】本発明の目的は、このような現状に対応す
べく、高価な合金元素の添加を極力抑え、なおかつＮＣ
Ｆ６２５クラスのＮｉ基合金やＳＵＳ３１０Ｓクラスの
ステンレス鋼に匹敵する優れた耐高温腐食特性を有する
オーステナイト系ステンレス鋼を提供することにある。[0007] An object of the present invention is to minimize the addition of expensive alloying elements while responding to the current situation.
An object of the present invention is to provide an austenitic stainless steel having excellent high-temperature corrosion resistance comparable to that of an F625 class Ni-based alloy or a SUS310S class stainless steel.
【０００８】[0008]
【課題を解決するための手段】本発明の目的は、質量％
で、 Ｃ：０．０６％以下 Ｓｉ：０．６％以下 Ｍｎ：０．２％以下 Ｐ：０．０３％以下 Ｓ：０．００５％以下 Ｎｉ：７〜１８％ Ｃｒ：１２〜２２％ Ｃｕ：０．１％以下 Ｍｏ：４．０％以下 Ｎ：０．０１％以下 を含有し、更に必要に応じて、上記成分において、 Ｃ：０．０１５％以下 Ｓｉ：０．１５％以下 Ｓ：０．００１％以下 Ｎ：０．０１％以下 に低減し、残部がＦｅおよび不可避的不純物よりなる、
塩化物環境下における耐溶融塩腐食性に優れたオーステ
ナイト系ステンレス鋼により達成される。SUMMARY OF THE INVENTION The object of the present invention is to provide a method for producing
C: 0.06% or less Si: 0.6% or less Mn: 0.2% or less P: 0.03% or less S: 0.005% or less Ni: 7 to 18% Cr: 12 to 22% Cu : 0.1% or less Mo: 4.0% or less N: 0.01% or less, and, if necessary, in the above components, C: 0.015% or less Si: 0.15% or less S: 0.001% or less N: reduced to 0.01% or less, with the balance being Fe and unavoidable impurities,
Achieved by austenitic stainless steel with excellent resistance to molten salt corrosion in chloride environments.
【０００９】[0009]
【発明の実施の形態】本発明者らは、上述したような現
状を鑑み、高価な合金元素の添加を極力抑えることによ
る高温腐食特性の改善を試みた。そして高温腐食特性に
及ぼす各種合金成分の影響について，鋭意検討を重ねた
結果、溶融塩腐食を加速させる要因となる、低融点化合
物や触媒酸化物を形成する元素を極力排除することによ
り、ＳＵＳ３０４、ＳＵＳ３１６クラスのＣｒ、Ｎｉ、
Ｍｏを含有するステンレス鋼においてＮＣＦ６２５に匹
敵する耐溶融塩腐食性を有するステンレス鋼が存在する
ことを明らかにし，本発明に至った。DESCRIPTION OF THE PREFERRED EMBODIMENTS In view of the above situation, the present inventors have attempted to improve high-temperature corrosion characteristics by minimizing the addition of expensive alloy elements. As a result of intensive studies on the effects of various alloying components on high-temperature corrosion characteristics, SUS304 and SUS304 have been removed by eliminating elements that form low-melting-point compounds and catalyst oxides, which are factors that accelerate molten salt corrosion. SUS316 class Cr, Ni,
The present inventors have clarified that a stainless steel having Mo salt corrosion resistance comparable to that of NCF625 exists in stainless steel containing Mo, which has led to the present invention.
【００１０】以下に本発明における各成分の作用とそれ
らの含有量の範囲を限定した理由を述べる。Hereinafter, the action of each component in the present invention and the reason for limiting the range of the content thereof will be described.
【００１１】Ｃは、高温で使用中に鋼中のＣｒと反応し
て結晶粒界にＣｒ炭化物を生成する。その結果、炭化物
近傍にＣｒ欠乏層を形成し、粒界腐食の原因となる。し
たがって、溶融塩腐食環境においてはＣは可能な限り低
減するのが望ましく、含有量は０．０６％以下、特に腐
食の厳しい環境では０．０１５質量％以下とするのがよ
い。C reacts with Cr in steel during use at a high temperature to form Cr carbide at grain boundaries. As a result, a Cr-deficient layer is formed in the vicinity of the carbide, which causes intergranular corrosion. Therefore, in a molten salt corrosion environment, it is desirable to reduce C as much as possible, and the content is preferably 0.06% or less, and particularly preferably in an environment with severe corrosion, 0.015% by mass or less.
【００１２】Ｓｉは一般に高温環境では、ステンレス鋼
の母相とＣｒ2Ｏ3の界面にＳｉＯ2として酸化皮膜を生
成し、耐酸化性を向上させる元素として知られている。
しかし、高温腐食環境においては、温度、溶融塩の種
類、雰囲気ガスの組成によってＳｉの効果が異なり、２
〜３％以上のＳｉを添加した場合には、安定なＳｉＯ2
皮膜の形成や母相の粒界への濃化によって耐溶融塩腐食
性が改善される。しかし、安定なＳｉ皮膜が形成されな
い場合には、Ｓｉは耐溶融塩腐食性に対し逆に有害とな
ることも知られている。本発明においては後述する各種
合金元素の低減により、Ｓｉを積極的に添加することな
しに耐溶融塩腐食性を改善している。このため、Ｓｉは
脱酸剤として添加する程度の量で十分であり、Ｓｉの含
有量は０．６％以下とした。特に腐食の厳しい環境では
０．１５質量％以下とするのが好ましい。In general, Si is known as an element that forms an oxide film as SiO 2 at the interface between the parent phase of stainless steel and Cr 2 O 3 in a high-temperature environment and improves oxidation resistance.
However, in a high-temperature corrosive environment, the effect of Si differs depending on the temperature, the type of molten salt, and the composition of the atmospheric gas.
When の 3% or more of Si is added, stable SiO 2
The formation of a film and the concentration of the matrix at the grain boundaries improve the molten salt corrosion resistance. However, it is also known that when a stable Si film is not formed, Si is harmful to molten salt corrosion resistance. In the present invention, the molten salt corrosion resistance is improved without actively adding Si by reducing various alloy elements described below. Therefore, the amount of Si to be added as a deoxidizing agent is sufficient, and the content of Si is set to 0.6% or less. Particularly in an environment where corrosion is severe, the content is preferably 0.15% by mass or less.
【００１３】Ｍｎは本発明において最も重要な元素であ
る。Ｍｎは、酸化雰囲気中では加熱初期に他の元素より
も多量に酸化され、その酸化皮膜はスケール最表層に形
成される。しかし、Ｍｎの酸化皮膜は酸化や溶融塩腐食
に対しては保護性がないため、Ｍｎの添加は有効でな
い。また、Ｍｎ系酸化物の内相に存在するＣｒ酸化物と
反応することにより生成したスピネル系酸化物は、Ｃｒ
酸化物よりも保護性が低い。このように、Ｍｎの過剰添
加は耐溶融塩腐食性に対して悪影響を及ぼすことから、
添加量は可能な限り少なくすることが好ましい。実施例
で示すように，本発明者らが溶融塩腐食に及ぼすＭｎの
影響を検討した結果、ＮＣＦ６２５クラスの鋼と同等の
耐食性を有するには、少なくとも、Ｍｎの添加量を０．
２質量％以下とする必要があることがわかった。したが
ってＭｎの含有量は０．２質量％以下とした。Mn is the most important element in the present invention. Mn is oxidized in an oxidizing atmosphere in a larger amount at the early stage of heating than other elements, and an oxide film is formed on the outermost layer of the scale. However, the addition of Mn is not effective because the oxide film of Mn has no protection against oxidation or molten salt corrosion. The spinel-based oxide produced by reacting with the Cr oxide present in the internal phase of the Mn-based oxide is Cr-based.
Less protective than oxides. As described above, since excessive addition of Mn adversely affects the molten salt corrosion resistance,
It is preferable to minimize the amount of addition. As shown in the examples, as a result of examining the effect of Mn on molten salt corrosion, the inventors of the present invention have found that at least the amount of Mn added must be at least 0.1 in order to have the same corrosion resistance as NCF625 class steel.
It was found that the content had to be 2% by mass or less. Therefore, the content of Mn is set to 0.2% by mass or less.
【００１４】Ｐは、鋼素地と腐食生成物との界面や母相
の粒界に偏析し、溶融塩による腐食や粒界侵食を促進さ
せる。したがって、その含有量は低いほど好ましく、本
発明においてはその値を０．０３％以下とした。P segregates at the interface between the steel substrate and the corrosion product and at the grain boundaries of the matrix, and promotes corrosion by molten salts and erosion at grain boundaries. Therefore, the content is preferably as low as possible, and in the present invention, the value is set to 0.03% or less.
【００１５】Ｓは、Ｐと同様に鋼素地と腐食生成物との
界面や母相の粒界に偏析し、溶融塩による腐食や粒界侵
食を促進させる。また、母相のＮｉや腐食生成物と反応
してその融点を下げ、より低い温度で溶融塩腐食を発生
させる可能性がある。これらを考慮すると、ステンレス
鋼中のＳは可能な限り低減する必要があり、本発明にお
いてはＳ含有量を０．００５％以下とした。特に腐食の
厳しい環境では０．００１質量％以下とするのが好まし
い。S, like P, segregates at the interface between the steel substrate and the corrosion product and at the grain boundaries of the parent phase, and promotes corrosion by molten salts and grain boundary erosion. In addition, it reacts with Ni of the parent phase and corrosion products to lower its melting point, and may cause molten salt corrosion at a lower temperature. In view of these, it is necessary to reduce S in stainless steel as much as possible. In the present invention, the S content is set to 0.005% or less. Particularly in an environment with severe corrosion, the content is preferably 0.001% by mass or less.
【００１６】ＮｉはＣｒと並び、ステンレス鋼を構成す
る主要元素である。高温腐食環境においては、Ｎｉは鋼
素地と腐食生成物の界面に濃化することによって、塩化
物による溶融塩腐食を抑制する。一方、Ｎｉは硫化物塩
と容易に反応し溶出するため、溶融塩中に硫化物が混在
している環境では、Ｎｉの過剰な添加は溶融塩腐食を促
進させる。塩化物環境のみでなく、塩化物と硫化物が混
在する環境においても耐溶融塩腐食性を低下させないよ
う、Ｎｉの範囲は７〜１８％とした。Ni is a main element constituting stainless steel along with Cr. In a high-temperature corrosive environment, Ni is concentrated at the interface between the steel substrate and the corrosion product, thereby suppressing molten salt corrosion due to chloride. On the other hand, since Ni easily reacts with and elutes with the sulfide salt, in an environment where sulfide is mixed in the molten salt, excessive addition of Ni promotes molten salt corrosion. The range of Ni is set to 7 to 18% so that the molten salt corrosion resistance is not reduced not only in the chloride environment but also in an environment where chloride and sulfide are mixed.
【００１７】Ｃｒは、高温酸化性を改善するのに非常に
有効な元素であるとともに、塩化物塩と硫化物塩が混在
する環境では、硫化物塩による溶融塩腐食性を改善す
る。均一で安定したＣｒ2Ｏ3皮膜を形成させるために
は、１２質量％以上の添加を必要とする。一方、過剰に
添加するとσ相などの脆化相を生成し、鋼の脆化を招
く。したがって、Ｃｒの範囲は１２質量％〜２２質量％
とした。[0017] Cr is a very effective element for improving high-temperature oxidizability, and improves the corrosion of molten salts by sulfide salts in an environment where chloride salts and sulfide salts coexist. In order to form a uniform and stable Cr 2 O 3 film, it is necessary to add 12% by mass or more. On the other hand, if it is added excessively, an embrittlement phase such as a σ phase is generated, resulting in embrittlement of steel. Therefore, the range of Cr is 12% by mass to 22% by mass.
And
【００１８】Ｃｕは酸化物を形成すると、触媒作用によ
り塩化物による溶融塩腐食を加速してしまうため、その
含有量はできるだけ少ない方が望ましく、０．１％以下
とした。When Cu forms an oxide, it accelerates molten salt corrosion by chloride due to catalytic action. Therefore, its content is desirably as small as possible, and is set to 0.1% or less.
【００１９】Ｍｏは特に塩化物環境における耐溶融塩腐
食性、耐粒界腐食性を向上させる効果がある。加えて、
低温においては耐露点腐食性に有効な元素である。従っ
て、断続運転を行う焼却炉などで、溶融塩腐食と露点腐
食が交互に生じる部位では特にその効果を発揮する。Ｍ
ｏの添加量が多ければ多いほどその効果は顕著になる
が、多量の添加はコストアップの要因となることから、
Ｍｏ添加量の上限を４．０％とした。Mo is particularly effective in improving the resistance to molten salt corrosion and the resistance to intergranular corrosion in a chloride environment. in addition,
At low temperatures, it is an effective element for dew point corrosion resistance. Therefore, the effect is particularly exerted in a portion where the molten salt corrosion and the dew point corrosion occur alternately in an incinerator or the like that performs an intermittent operation. M
The effect becomes more remarkable as the addition amount of o increases, but since the addition of a large amount causes a cost increase,
The upper limit of the amount of Mo added was 4.0%.
【００２０】Ｎは、Ｃと同様に粒界に窒化物として析出
しＣｒ欠乏層を生じさせ、粒界の耐溶融塩腐食性を劣化
させる。Ｎの若干の添加が粒界腐食の改善に有効である
との開示例もあるが、本発明においては積極的に添加し
なくても十分な耐溶融塩腐食性を有する。したがって、
粒界析出防止の観点からＮの添加量を０．０３％以下と
した。特に腐食の厳しい環境では、０．０１％以下とす
るのが好ましい。N, like C, precipitates at the grain boundaries as nitrides to form a Cr-deficient layer, deteriorating the molten salt corrosion resistance of the grain boundaries. Although there is a disclosure that some addition of N is effective in improving intergranular corrosion, the present invention has sufficient molten salt corrosion resistance even if it is not actively added. Therefore,
From the viewpoint of preventing grain boundary precipitation, the amount of N added is set to 0.03% or less. In an environment where corrosion is particularly severe, the content is preferably 0.01% or less.
【００２１】上述した成分の他に、ＡｌはＳｉと同様な
効果が期待できるものの、本発明においては積極的に添
加しなくても十分な特性が得られるので、Ａｌの添加量
は脱酸剤として必要な量である０．１％質量以下含有す
ればよい。また、本発明は、耐溶融塩腐食性に悪影響を
及ぼす鋼中不純物元素に対して、その影響を低減させる
元素の添加は制限されない。例えば、鋼中のＳを固定す
る希土類元素やＣａは０．０５質量％、鋼中のＣやＮを
固定するＴｉ，Ｖ，Ｚｒ，Ｎｂ，Ｈｆ，Ｔａ，Ｗ，Ｒｅ
などは０．１質量％を上限として添加することができ
る。In addition to the above-mentioned components, Al can be expected to have the same effect as Si, but in the present invention, sufficient characteristics can be obtained without actively adding it. May be contained in a necessary amount of 0.1% by mass or less. Further, in the present invention, the addition of an element that reduces the influence of impurity elements in steel that adversely affects the molten salt corrosion resistance is not limited. For example, rare earth elements and Ca for fixing S in steel are 0.05% by mass, and Ti, V, Zr, Nb, Hf, Ta, W, and Re for fixing C and N in steel.
Can be added with the upper limit being 0.1% by mass.
【００２２】[0022]
【実施例】以下に本願の実施例を示す。表１に供試材の
化学成分を示した。表中のＡ−１〜Ａ−９の鋼が本発明
方法の範囲に含まれる鋼である。Ｂ−１〜Ｂ−５は本発
明の方法に含まれないＳＵＳ３０４系、ＳＵＳ３１６
系、およびＳＵＳ３１０Ｓ系の比較鋼である。またＣ−
１、Ｃ２はそれぞれＦｅ基高合金のＮＣＦ８２５および
Ｎｉ基高合金のＮＣＦ６２５である。これらの鋼を溶製
し、圧延、焼鈍を繰り返して板厚２ｍｍの試験片を作成
した。作成した試験片に合成灰（組成：ＮａＣｌ−ＫＣ
ｌ(モル比１：１））を調合し、これをアセトン中に分
散させたものを、１０ｍｇ／ｃｍ2の塗布量で、試験片
表面に均一に塗布した。そして、これら合成灰を塗布し
た試験片を、２０％Ｈ2０，１０％０2，５％ＣＯ2，１
０００ｐｐｍＮａＣｌ、残りがＮ２の組成のガス中で６
５０℃×５０時間加熱し、加熱後の試験片について腐食
試験を実施し、腐食減量を調べた。その結果を表２に示
す。Embodiments of the present invention will be described below. Table 1 shows the chemical components of the test materials. Steels A-1 to A-9 in the table are steels included in the scope of the method of the present invention. B-1 to B-5 are SUS304 series, SUS316 which are not included in the method of the present invention.
And SUS310S based steels. Also C-
Reference numerals 1 and C2 denote NCF825 of an Fe-based high alloy and NCF625 of a Ni-based high alloy, respectively. These steels were melted, and rolling and annealing were repeated to prepare test pieces having a thickness of 2 mm. Synthetic ash (composition: NaCl-KC)
1 (molar ratio 1: 1)), and the resulting mixture was dispersed in acetone and uniformly applied to the test piece surface at an application amount of 10 mg / cm 2 . Then, the test pieces coated with the synthetic ash were subjected to 20% H 2 0,10% 0 2 , 5% CO 2 , 1
6 ppm NaCl, the balance being N2
The test piece was heated at 50 ° C. for 50 hours, and a corrosion test was performed on the test piece after heating to examine the corrosion weight loss. Table 2 shows the results.
【００２３】[0023]
【表１】 [Table 1]
【００２４】[0024]
【表２】 [Table 2]
【００２５】表２の結果をみると、発明鋼であるＡ−１
〜Ａ−９の腐食減量は、いずれも３０ｍｇ／ｃｍ2以下
であり、比較鋼であるＦｅ基、Ｎｉ基高合金（Ｃ−１、
Ｃ−２）と同程度の良好な耐食性を示していることがわ
かる。これに対し、比較鋼のＢ−１、Ｂ−２、Ｂ−４、
Ｂ−５は、Ｍｎが本発明で規定する濃度から外れている
ため、腐食減量が多くなっている。また、Ｂ−３は２５
Ｃｒ−２０Ｎｉ系のＳＵＳ３１０Ｓであるが、Ｓｉ、Ｍ
ｎ、Ｃｕが本発明の範囲から外れるため、本発明鋼より
も腐食減量は大きい。From the results in Table 2, it can be seen that the invention steel A-1
-A-9 had a corrosion weight loss of 30 mg / cm 2 or less, and the comparative steels Fe-based and Ni-based high alloys (C-1,
It turns out that it shows the same good corrosion resistance as C-2). In contrast, the comparative steels B-1, B-2, B-4,
B-5 has a large corrosion weight loss because Mn is out of the concentration specified in the present invention. B-3 is 25
Cr-20Ni-based SUS310S, but Si, M
Since n and Cu are out of the range of the present invention, the corrosion weight loss is larger than that of the steel of the present invention.
【００２６】図１に腐食減量におよぼすＭｎ量の影響を
示す。図１で示すように、本発明の範囲である、Ｍｎ量
が０．２質量％以下の鋼は、１８Ｃｒ−１１〜１３Ｎｉ
系および１８Ｃｒ−１２〜１３Ｎｉ−２Ｍｏ系であるに
もかかわらず、Ｆｅ基、Ｎｉ基高合金であるＣ−１，Ｃ
−２と同等の耐溶融塩腐食性を示している。FIG. 1 shows the effect of the amount of Mn on the corrosion weight loss. As shown in FIG. 1, steels having a Mn content of 0.2% by mass or less, which are within the scope of the present invention, are 18Cr-11 to 13Ni.
Fe-based and Ni-based high alloys C-1 and C in spite of being based on 18Cr-12-13Ni-2Mo
-2 shows molten salt corrosion resistance equivalent to -2.
【００２７】[0027]
【発明の効果】本発明は、ＳＵＳ３０４、ＳＵＳ３１６
クラスのＣｒ、Ｎｉ、Ｍｏ量でありながら、その耐溶融
塩腐食性はＳＵＳ３１０Ｓを凌駕し、高合金に匹敵する
塩化物溶融塩腐食性に優れたステンレス鋼に関するもの
である。従って、例えば廃棄物焼却炉のボイラーチュー
ブなど、塩化物を含む溶融塩腐食環境にさらされる環境
において、腐食の厳しい部位で使用されているＦｅ基お
よびＮｉ基高合金に対して本発明鋼を代替できる上、こ
れら高合金より加工性、成形性に優れているため、より
複雑な形状を要求される熱交換器等への用途に適してい
る。また、ＳＵＳ３１０Ｓが使用されている部位におい
ても、より長寿命化が期待される上、ＳＵＳ３１０Ｓに
比較しても優れた加工性、溶接性を有するため、より多
くの部位へ適用可能である。すなわち、本発明のステン
レス鋼を、塩化物下における溶融塩腐食が生じる環境、
部位に用いた場合、加工、溶接などがより容易になるこ
と、メンテナンスコストの低減につながる等の利点があ
り、本発明は、環境問題のために規制が厳しくなり、よ
り耐久性が要求されるようになった昨今の焼却炉におけ
る材料問題の改善に寄与することができる。According to the present invention, SUS304, SUS316
The present invention relates to a stainless steel having a molten salt corrosion resistance superior to that of SUS310S and excellent in chloride molten salt corrosion resistance, which is comparable to that of a high alloy, even though the amount of Cr, Ni, and Mo is in a class. Therefore, the steel of the present invention can be substituted for Fe-based and Ni-based high alloys used in severely corroded environments in environments exposed to molten salt corrosion containing chlorides, such as boiler tubes in waste incinerators. In addition to its high workability and formability, these high alloys are suitable for use in heat exchangers and the like that require more complicated shapes. Further, even in a part where SUS310S is used, a longer life is expected, and since it has excellent workability and weldability as compared with SUS310S, it can be applied to more parts. That is, the stainless steel of the present invention is used in an environment where molten salt corrosion occurs under chloride,
When used for a part, there are advantages such as easier processing, welding, etc., leading to a reduction in maintenance cost, and the present invention requires stricter regulation due to environmental problems and more durability. It is possible to contribute to the improvement of material problems in recent incinerators.
【図１】塩化物溶融塩腐食試験後の腐食減量と、供試材
中に含まれるＭｎ量との関係を示した図。FIG. 1 is a graph showing the relationship between the corrosion weight loss after a chloride molten salt corrosion test and the amount of Mn contained in a test material.
Claims (2)
化物環境下における耐溶融塩腐食性に優れたオーステナ
イト系ステンレス鋼。1. In mass% C: 0.06% or less Si: 0.6% or less Mn: 0.2% or less P: 0.03% or less S: 0.005% or less Ni: 7 to 18% Cr : 12 to 22% Cu: 0.1% or less Mo: 4% or less N: 0.03% or less, with the balance being Fe and unavoidable impurities, excellent in molten salt corrosion resistance in a chloride environment Austenitic stainless steel.
化物環境下における耐溶融塩腐食性に優れたオーステナ
イト系ステンレス鋼。2. In mass% C: 0.015% or less Si: 0.15% or less Mn: 0.2% or less P: 0.03% or less S: 0.001% or less Ni: 7 to 18% Cr : 22% to 22% Cu: 0.1% or less Mo: 4.0% or less N: 0.01% or less, with the balance being Fe and unavoidable impurities, the molten salt corrosion resistance in a chloride environment Excellent austenitic stainless steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11125678A JP2000319761A (en) | 1999-05-06 | 1999-05-06 | Austenitic stainless steel excellent in molten salt corrosion resistance in chloride environment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11125678A JP2000319761A (en) | 1999-05-06 | 1999-05-06 | Austenitic stainless steel excellent in molten salt corrosion resistance in chloride environment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000319761A true JP2000319761A (en) | 2000-11-21 |
Family
ID=14915968
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11125678A Withdrawn JP2000319761A (en) | 1999-05-06 | 1999-05-06 | Austenitic stainless steel excellent in molten salt corrosion resistance in chloride environment |
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| Country | Link |
|---|---|
| JP (1) | JP2000319761A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009079240A (en) * | 2007-09-25 | 2009-04-16 | Tohoku Univ | Austenitic stainless steel and its manufacturing method, reactor internal structure and piping |
| US20220282350A1 (en) * | 2019-08-29 | 2022-09-08 | Mannesmann Stainless Tubes GmbH | Austenitic steel alloy having an improved corrosion resistance under high-temperature loading and method for producing a tubular body therefrom |
| CN116623102A (en) * | 2023-05-11 | 2023-08-22 | 坤石容器制造有限公司 | Ultra-purified austenitic stainless steel for high-pressure hydrogen storage and preparation method thereof |
| JP2024103391A (en) * | 2023-01-20 | 2024-08-01 | Ｊｆｅスチール株式会社 | Stainless steel for Ni brazing, joints, heat exchangers and water heaters |
-
1999
- 1999-05-06 JP JP11125678A patent/JP2000319761A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009079240A (en) * | 2007-09-25 | 2009-04-16 | Tohoku Univ | Austenitic stainless steel and its manufacturing method, reactor internal structure and piping |
| US20220282350A1 (en) * | 2019-08-29 | 2022-09-08 | Mannesmann Stainless Tubes GmbH | Austenitic steel alloy having an improved corrosion resistance under high-temperature loading and method for producing a tubular body therefrom |
| JP2024103391A (en) * | 2023-01-20 | 2024-08-01 | Ｊｆｅスチール株式会社 | Stainless steel for Ni brazing, joints, heat exchangers and water heaters |
| JP7667189B2 (en) | 2023-01-20 | 2025-04-22 | Ｊｆｅスチール株式会社 | Stainless steel for Ni brazing, joints, heat exchangers and water heaters |
| CN116623102A (en) * | 2023-05-11 | 2023-08-22 | 坤石容器制造有限公司 | Ultra-purified austenitic stainless steel for high-pressure hydrogen storage and preparation method thereof |
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