JPH0280552A - Heat treatment for stainless steel for heater tube - Google Patents
Heat treatment for stainless steel for heater tubeInfo
- Publication number
- JPH0280552A JPH0280552A JP23083788A JP23083788A JPH0280552A JP H0280552 A JPH0280552 A JP H0280552A JP 23083788 A JP23083788 A JP 23083788A JP 23083788 A JP23083788 A JP 23083788A JP H0280552 A JPH0280552 A JP H0280552A
- Authority
- JP
- Japan
- Prior art keywords
- heater tube
- oxide film
- stainless steel
- heat treatment
- nitric acid
- 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
- 238000010438 heat treatment Methods 0.000 title claims abstract description 47
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 28
- 239000010935 stainless steel Substances 0.000 title claims abstract description 26
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims abstract description 25
- 229910000423 chromium oxide Inorganic materials 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 22
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 21
- 239000011651 chromium Substances 0.000 claims abstract description 17
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 17
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000001301 oxygen Substances 0.000 claims abstract description 16
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 15
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 14
- 239000011261 inert gas Substances 0.000 claims abstract description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 6
- 239000010959 steel Substances 0.000 claims description 6
- 238000010828 elution Methods 0.000 abstract description 20
- 229910052751 metal Inorganic materials 0.000 abstract description 16
- 239000002184 metal Substances 0.000 abstract description 16
- 230000000694 effects Effects 0.000 abstract description 12
- 238000010306 acid treatment Methods 0.000 abstract description 6
- 150000002739 metals Chemical class 0.000 abstract description 3
- -1 Ni and Co Chemical class 0.000 abstract description 2
- 230000002401 inhibitory effect Effects 0.000 abstract 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 238000005260 corrosion Methods 0.000 description 11
- 230000007797 corrosion Effects 0.000 description 11
- 239000000463 material Substances 0.000 description 10
- 239000002253 acid Substances 0.000 description 6
- 238000009835 boiling Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 3
- 238000001953 recrystallisation Methods 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- UOUJSJZBMCDAEU-UHFFFAOYSA-N chromium(3+);oxygen(2-) Chemical class [O-2].[O-2].[O-2].[Cr+3].[Cr+3] UOUJSJZBMCDAEU-UHFFFAOYSA-N 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 230000005855 radiation Effects 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 206010070834 Sensitisation Diseases 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001651 emery Inorganic materials 0.000 description 1
- 229960002050 hydrofluoric acid Drugs 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000001637 plasma atomic emission spectroscopy Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001603 reducing effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000008313 sensitization Effects 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、高温高圧水環境下で用いられるステンレス鋼
からなる加熱器管、例えば沸騰水型原子炉（ＢＷＲ）の
給水加熱器管や湿分分離加熱器管における腐食生成物の
発生を抑制するのに有効な耐食皮膜を形成させるための
熱処理方法に関するものである。Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to heater tubes made of stainless steel used in high-temperature, high-pressure water environments, such as feed water heater tubes for boiling water reactors (BWR) and The present invention relates to a heat treatment method for forming a corrosion-resistant film that is effective in suppressing the generation of corrosion products in a separation heater tube.
（従来の技術）
高温高圧水環境下で用いられる加熱器管、例えば沸騰水
型原子炉の給水加熱器管や湿分分離加熱器管の材料には
、ＳＯ５３０４Ｌなどの耐食性に優れたオーステナイト
系ステンレス鋼が用いられている。しかし、長期間使用
する間に腐食され、材料中のＮｉやＣｏが一次冷却水中
に溶出して原子炉内に持ち込まれ、中性子照射を受けて
放射化し、この放射化されたＮｉやＣｏを含むクラッド
（腐食生成物）が配管や加熱器管等に沈着して、定期検
査等において作業者が被曝されるなどの安全衛生上の問
題が生じる。(Prior art) Materials for heater tubes used in high-temperature, high-pressure water environments, such as feed water heater tubes and moisture separation heater tubes for boiling water reactors, include austenitic stainless steel with excellent corrosion resistance such as SO5304L. Steel is used. However, during long-term use, it corrodes, and the Ni and Co in the materials are eluted into the primary cooling water and brought into the reactor, where they are activated by neutron irradiation, and the activated Ni and Co are included. Crud (corrosion products) is deposited on pipes, heater tubes, etc., causing health and safety problems such as workers being exposed to radiation during periodic inspections.
そこで、このようなＮｉやＣｏの溶出を抑制し、これら
による放射線量の低減をはかるための一つの方法として
、酸素を注入した高温水で沸騰水型原子炉のステンレス
製給水加熱器のヒータチューブに腐食に対して保護的な
酸化皮膜を形成する方法およびその装置が提案されてい
る（特開昭６１−１３９６７６号公報）。Therefore, one method to suppress the elution of Ni and Co and thereby reduce the radiation dose is to use high-temperature water injected with oxygen to heat the heater tubes of stainless steel feed water heaters in boiling water reactors. A method and apparatus for forming a protective oxide film against corrosion have been proposed (Japanese Unexamined Patent Publication No. 139676/1983).
しかし、この方法は実炉で行うため酸化皮膜形成に長時
間を要し、また、処理温度や時間などの制限から金属の
溶出を抑制するのに最適な酸化皮膜を形成するのが困難
である。However, since this method is carried out in an actual furnace, it takes a long time to form an oxide film, and it is difficult to form an oxide film that is optimal for suppressing metal elution due to limitations such as processing temperature and time. .
（発明が解決しようとする課題）
本発明の課題は、高温高圧水環境下で使用されるステン
レス鋼からなる加熱器管、例えば沸騰水型原子炉の給水
加熱器管や湿分分離加熱器管の表面に、ＮｉやＣＯの溶
出を抑制するのに効果のある主にクロム酸化物からなる
緻密な酸化皮膜を容易に且つ適正な厚みに形成すること
ができる方法を提供することにある。(Problem to be Solved by the Invention) The problem to be solved by the present invention is to solve the problem of a heater tube made of stainless steel used in a high-temperature, high-pressure water environment, such as a feed water heater tube of a boiling water reactor or a moisture separation heater tube. It is an object of the present invention to provide a method for easily forming a dense oxide film consisting mainly of chromium oxide, which is effective in suppressing the elution of Ni and CO, on the surface of a steel and has an appropriate thickness.
（！１ｕｌｌ！を解決するための手段）本発明者は、ス
テンレス鋼からなる加熱器管を微量の酸素を含む不活性
ガス雰囲気中で、加熱温度および加熱時間を特定の範囲
に禰整して熱処理すれば、その表面にＮｉやＣｏの溶出
抑制効果のあるクロム酸化物を主体とする酸化皮膜を形
成することができることを見出し、先に特許出願した（
特願昭６３−１９７６３０号）。(Means for solving !1ull!) The present inventor has developed a heater tube made of stainless steel in an inert gas atmosphere containing a trace amount of oxygen, by controlling the heating temperature and heating time to a specific range. We discovered that heat treatment can form an oxide film mainly composed of chromium oxide, which has the effect of suppressing the elution of Ni and Co, and we have previously applied for a patent (
(Patent Application No. 197630, 1983).
上記先願発明の方法でも十分にＮｉやＣＯの溶出を抑制
することができるが、本発明者はこれに満足することな
く更に研究を重ねた結果、熱処理前に加熱器管を熱処理
に比べてより緻密な酸化皮膜を形成させることができる
酸溶液、具体的には硝酸溶液で処理し、その表面に予め
クロム酸化物を主体とする緻密な下地皮膜を適量形成さ
せた後、これを特定の条件で熱処理してやれば、前記下
地皮膜の上にエピタキシャル的に緻密なりロム酸化物を
主体とする酸化皮膜が生成し、前記先願発明の方法に比
べて金属溶出抑制効果、特にＮｉｉ出抑側抑制効果段と
向上することを見出し、本発明に至った。Although the method of the prior invention described above can sufficiently suppress the elution of Ni and CO, the present inventor was not satisfied with this and conducted further research. After treating the surface with an acid solution that can form a denser oxide film, specifically a nitric acid solution, and forming an appropriate amount of a dense base film mainly composed of chromium oxide on the surface, this is treated with a specific oxide film. If the heat treatment is carried out under these conditions, an epitaxially dense oxide film mainly composed of chromium oxide will be formed on the base film, and the effect of suppressing metal elution, especially the suppression of Nii release, will be greater than that of the method of the prior invention. It was discovered that the effect was significantly improved, and the present invention was developed.
ここに、本発明の要旨は「重量％で、Ｃｒを１２〜２０
％含有するステンレス鋼からなる加熱器管、又はＣｒを
１２〜２０％とＮｉを４０％以下含有するステンレス鋼
からなる加熱器管を、濃度１０〜４０％の硝酸溶液で処
理し、その表面にクロム酸化物を主体とする酸化皮膜を
形成させた後、０．００５〜Ｑ、１ｖｏｊ！％の酸素を
含む不活性ガス雰囲気中で、添付第１図に示す点ＡとＢ
％ＢとＣ，ＣとＤＳＤとＥ、ＥとＦ、ＦとＡをそれぞれ
結ぶ直線によって囲まれる領域内の加熱温度および加熱
時間で熱処理し、表面にクロム酸化物を主体とする酸化
皮膜を更に形成させることを特徴とする加熱器管用ステ
ンレス鋼の熱処理方法」にある。Here, the gist of the present invention is ``Cr content is 12 to 20% by weight.
%, or a heater tube made of stainless steel containing 12 to 20% Cr and 40% or less Ni is treated with a nitric acid solution with a concentration of 10 to 40%, and its surface is coated with After forming an oxide film mainly composed of chromium oxide, 0.005 to Q, 1 voj! In an inert gas atmosphere containing % oxygen, points A and B shown in the attached Figure 1
%B and C, C and DSD and E, E and F, and F and A are heat treated at the heating temperature and heating time within the area surrounded by straight lines connecting them, respectively, to further form an oxide film mainly composed of chromium oxide on the surface. "Heat treatment method for stainless steel for heater tubes" characterized by forming the stainless steel.
添付第１図は、本発明にかかる熱処理方法で採用する加
熱温度と加熱時間との関係を示したものである。The attached FIG. 1 shows the relationship between the heating temperature and heating time employed in the heat treatment method according to the present invention.
即ち、本発明の熱処理方法はステンレス鋼からなる加熱
器管を、予め硝酸溶液で処理した後、微量の酸素を含む
不活性ガス、例えば微量の酸素を含むアルゴンガス雰囲
気中で、加熱温度と加熱時間との関係を示す添付図の点
Ａ （１１００℃、２分）、Ｂ （９００℃、２分）、
Ｃ（８００℃、２０分）、Ｄ （９５０，２０分）、Ｅ
（１０００℃、５分）およびＦ（１１００’Ｃ１５分
）の６点を結ぶ直線によって囲まれる領域内の加熱温度
および加熱時間で熱処理して、表面にクロム酸化物（Ｃ
ｒｓＬ）を主体とするより緻密な酸化皮膜を形成させる
のである。That is, in the heat treatment method of the present invention, a heater tube made of stainless steel is treated in advance with a nitric acid solution, and then heated at a certain temperature in an inert gas atmosphere containing a trace amount of oxygen, such as an argon gas atmosphere containing a trace amount of oxygen. Points A (1100℃, 2 minutes), B (900℃, 2 minutes) in the attached diagram showing the relationship with time,
C (800℃, 20 minutes), D (950, 20 minutes), E
(1000°C, 5 minutes) and F (1100°C, 15 minutes).
This results in the formation of a denser oxide film mainly consisting of rsL).
なお、本発明において上記熱処理はこれのみを別途実施
してもよいが、素材のステンレス鋼から加熱器管を製造
する工程の中の再結晶焼鈍工程を利用して行うのがよい
、再結晶焼鈍の条件を上記の条件に調整して熱処理すれ
ば、再結晶と酸化皮膜形成を同時に行わしめることがで
きるので、酸化皮膜を形成させるための熱処理を別途新
たに実施しな（でもよい。In addition, in the present invention, the above heat treatment may be performed separately, but it is preferable to perform the recrystallization annealing process in the process of manufacturing the heater tube from the stainless steel material. If the conditions are adjusted to the above conditions and heat treatment is performed, recrystallization and oxide film formation can be performed simultaneously, so there is no need to separately perform a new heat treatment to form an oxide film.
（作用） 以下、本発明について具体的に説明する。(effect) The present invention will be specifically explained below.
本発明の特徴とするところは、Ｃｒを１２〜２０％含有
するステンレス鋼からなる加熱器管、又はＣｒを１２〜
２０％とＮｉを４０％以下含有するステンレス鋼からな
る加熱器管を、熱処理でクロム酸化物を主体とする酸化
皮膜を生成させてやる前に、予め加熱器管を濃度ｌＯ〜
４０％の硝酸溶液で処理して、その表面に主にクロム酸
化物からなる下地皮膜を生成させるところにある。The present invention is characterized by a heater tube made of stainless steel containing 12 to 20% Cr, or a heater tube made of stainless steel containing 12 to 20% Cr.
Before heating a heater tube made of stainless steel containing 20% Ni and 40% Ni or less to generate an oxide film mainly composed of chromium oxide, the heater tube is heated to a concentration of lO~
It is treated with a 40% nitric acid solution to form a base film consisting mainly of chromium oxide on the surface.
前記加熱器管の材料を、Ｃｒを１２〜２０％含有するス
テンレス鋼、又はＣｒを１２〜２０％とＮｉを４０％以
下含有するステンレス鋼とする理由は、Ｃｒ又ハＣｒ！
：Ｎｉをこれより多く含むステンレス鋼からなる加熱器
管では、本発明方法のような処理を施して酸化皮膜を付
与してやらなくとも耐食性が良好で、高温水中でもＮｉ
やＣＯの溶出量が極めて少ないからである。また、Ｃｒ
含有量が１２％未満のステンレス鋼は、本発明が意図す
る分野では使用されないからである。The reason why the material of the heater tube is stainless steel containing 12 to 20% Cr, or stainless steel containing 12 to 20% Cr and 40% or less Ni is because Cr or Cr!
: Heater tubes made of stainless steel containing more Ni than this have good corrosion resistance even without applying the treatment as in the method of the present invention to form an oxide film, and even in high-temperature water the Ni
This is because the amount of elution of CO and CO is extremely small. Also, Cr
This is because stainless steel with a content of less than 12% is not used in the field intended by the present invention.
このようなＣｒを１２〜２０％、又はＣｒを１２〜２０
％とＮｉを４０％以下含有するステンレス鋼としては、
Ａｌ５ｌ 丁Ｖｐｅ ３０４Ｌ綱、同３１６Ｌ鋼などの
オーステナイト系ステンレス鋼や１８％のＣｒを含有す
る同４３９１１．１３％のＣ「を含有する同４１０鋼な
どのフェライト系ステンレス鋼が代表的である。12-20% of such Cr, or 12-20% of Cr
As stainless steel containing 40% or less of Ni,
Typical examples include austenitic stainless steels such as Al5l 304L steel and 316L steel, and ferritic stainless steels such as 410 steel containing 18% Cr and 13% C.
本発明は、このようなステンレス鋼からなる加熱器管を
、熱処理する前に濃度１０〜４０％の硝酸溶液に浸漬し
、その表面に主にクロム酸化物からなる下地皮膜を予め
形成させる。この処理で用いる酸を硝酸とする理由は、
これ以外の酸例えば、塩酸や硫酸は活性溶解型の還元性
の強い酸であるので酸化皮膜の生成に使うことができな
い。また硝弗酸は腐食性が極めて大きく、母材表面を凹
凸状に溶解して製品品質を損なうので使用することがで
きない、これに対して硝酸は適正な条件で使用すれば、
上記のような凹凸を生じさせることなく主にクロム酸化
物からなる緻密な下地皮膜を生成させることができる。In the present invention, such a heater tube made of stainless steel is immersed in a nitric acid solution having a concentration of 10 to 40% before heat treatment, and a base film mainly made of chromium oxide is previously formed on the surface of the heater tube. The reason for using nitric acid as the acid used in this process is
Other acids such as hydrochloric acid and sulfuric acid cannot be used to form an oxide film because they are actively dissolving acids with strong reducing properties. In addition, nitric-fluoric acid cannot be used because it is extremely corrosive and dissolves the base material surface into irregularities, impairing product quality.On the other hand, nitric acid, if used under appropriate conditions,
A dense base film mainly consisting of chromium oxide can be produced without producing the above-mentioned irregularities.
しかし、硝酸濃度が１０％未満では腐食反応が遅いので
、クロム酸化物からなる下地皮膜を容易に得ることがで
きず、４０％を超える濃度では腐食が促進されるものの
孔食等の凹凸が発生し易くなる。However, if the nitric acid concentration is less than 10%, the corrosion reaction is slow, so it is not easy to obtain a base film made of chromium oxide, and if the concentration exceeds 40%, corrosion will be accelerated, but pitting and other irregularities will occur. It becomes easier to do.
この硝酸処理では、酸濃度を規定してやれば所望の厚み
の主にクロム酸化物からなるの下地皮膜を加熱器管表面
に適正な厚みで付与することができるが、望ましくは処
理温度については４０〜１００℃、浸漬時間については
０．１〜２時間時間色して処理するのがよい、処理温度
が４０°Ｃより低いと腐食反応が遅くて酸化物の成長が
起こり難く、１００℃を超えると硝酸が沸騰（沸点：お
よそ１００℃）するので、下地皮膜を形成させようとす
ればオートクレーブなどの特別な圧力容器を必要とする
。そのために製造コストが嵩み工業的な実施には不利で
ある。また、浸漬時間が０．１時間より短いと主にクロ
ム酸化物からなる下地皮膜が得られず、２時間を超えて
浸漬してもそれまでにおよそ１００人程変色不働態保護
皮膜が生成されているので、それ以上に腐食が進まず、
酸化皮膜成長が飽和する。In this nitric acid treatment, if the acid concentration is specified, it is possible to apply a base film of a desired thickness, mainly consisting of chromium oxide, to the surface of the heater tube, but the treatment temperature is preferably 40~40°C. It is best to color and process at 100℃ for 0.1 to 2 hours for immersion time.If the treatment temperature is lower than 40℃, the corrosion reaction will be slow and oxide growth will be difficult to occur, but if it exceeds 100℃ Since nitric acid boils (boiling point: approximately 100°C), a special pressure vessel such as an autoclave is required to form a base film. This increases manufacturing costs and is disadvantageous for industrial implementation. Also, if the immersion time is shorter than 0.1 hour, a base film consisting mainly of chromium oxide will not be obtained, and even if immersed for more than 2 hours, about 100 discolored passive protective films will be formed. Because the corrosion does not progress further,
Oxide film growth is saturated.
このような条件で熱処理前に予め加熱器管を硝酸処理し
てやれば、表面におよそ５０〜１５０人程度の主変色ロ
ム酸化物からなる緻密な下地皮膜が形成される。そして
、この下地皮膜を形成した加熱器管を、ｏ、 ｏｏｓ〜
０．１ｖｏｊ２％の酸素を含む不活性ガス雰囲気中で、
添付第１図に示す点Ａ〜点Ｆの各点をそれぞれ結ぶ直線
によって囲まれる領域内の加熱温度と加熱時間で熱処理
し、前記下地皮膜の上に更にクロム酸化物を主体とする
酸化皮膜を生成させてやる。この熱処理において、不活
性ガス雰囲気中の酸素濃度をｏ、ｏｏｓ〜０．ｌｖｏ１
％とする理由は、酸素濃度が０．００５ｖｏ １％未満
では、ＮｉやＧ。If the heater tube is treated with nitric acid before heat treatment under these conditions, a dense base film consisting of about 50 to 150 chromium oxides will be formed on the surface. Then, the heater tube on which this base film was formed was o, oos~
In an inert gas atmosphere containing 0.1voj2% oxygen,
Heat treatment is performed at a heating temperature and heating time within the area surrounded by straight lines connecting points A to F shown in attached Figure 1, and an oxide film mainly composed of chromium oxide is further formed on the base film. I'll generate it. In this heat treatment, the oxygen concentration in the inert gas atmosphere is set to o, oos to 0. lvo1
The reason why it is set as % is that when the oxygen concentration is less than 0.005vo 1%, Ni and G.
の金属溶出抑制に有効な厚さがおよそ３００〜１０００
人のクロム酸化物主体の酸化皮膜を形成することができ
ず、Ｏ，ｌｖｏ １％を超える酸素濃度では、得られる
酸化皮膜が必要以上に厚くなりすぎて皮膜にひび割れや
皮膜剥離が生じ易くなり、逆に金属溶出抑制効果が減少
するからである。The effective thickness for suppressing metal elution is approximately 300 to 1000.
Humans cannot form an oxide film consisting mainly of chromium oxide, and at oxygen concentrations exceeding 1% O,lvo, the resulting oxide film becomes too thick than necessary and tends to cause cracks and peeling of the film. This is because, on the contrary, the effect of suppressing metal elution decreases.
本発明方法における不活性ガス雰囲気中の酸素濃度は前
掲の先願発明よりも低い、これは先願発明では、硝酸処
理を施さずクロム酸化物を主体とする酸化皮膜を熱処理
により直接加熱器管の表面に形成するので、クロム酸化
物の核生成および成長を行わしめるためには高い濃度の
酸素を必要とする。しかし、本発明方法では予め下地皮
膜を形成させているので、熱処理により生成する酸化皮
膜が、この皮膜の上にエピタキシャル的に成長するため
に低酸素濃度でも十分な厚みの酸化皮膜を生成させるこ
とができるのである。そして、下地皮膜の上に得られる
新たな酸化皮膜も緻密なものとなる、この理由は、下地
皮膜の上に成長する酸化皮膜は、下地皮膜の結晶構造を
そのまま受けついでエピタキシャル的に成長する性質を
有するからである。The oxygen concentration in the inert gas atmosphere in the method of the present invention is lower than that in the prior invention mentioned above. Since chromium oxide forms on the surface of chromium oxide, a high concentration of oxygen is required for nucleation and growth of chromium oxide. However, in the method of the present invention, since the base film is formed in advance, the oxide film generated by heat treatment grows epitaxially on this film, so it is difficult to form a sufficiently thick oxide film even at low oxygen concentrations. This is possible. The new oxide film obtained on the base film will also be dense.The reason for this is that the oxide film that grows on the base film grows epitaxially, inheriting the crystal structure of the base film as it is. This is because it has
また、加熱時間および加熱温度を添付第１図の斜線で示
す範囲内に限定する理由は、下記の通りである。Further, the reason why the heating time and heating temperature are limited to the range shown by diagonal lines in the attached FIG. 1 is as follows.
加熱時間がＡＢ線で示される２分およびＢＣ線で示され
る２〜２０分より短いと、形成される酸化皮膜は薄く高
温水中でＮｉやＣｏ等の金属の溶出を抑制するのに有効
な厚さの酸化皮膜が得られず、また、ＥＦ線で示される
５分、ＤＢ線で示される５〜２０分およびＤＣ線で示さ
れる２０分より長く加熱すると、形成される酸化皮膜は
厚くなり過ぎて、皮膜にひび割れや皮膜剥離が発生しや
すくなり、逆に金属の溶出抑制効果が減少する。If the heating time is shorter than 2 minutes as shown by the AB line and 2 to 20 minutes as shown by the BC line, the oxide film formed will be thin and have a thickness that is effective for suppressing the elution of metals such as Ni and Co in high-temperature water. If a thick oxide film is not obtained, and if heating is performed for longer than 5 minutes as shown by the EF line, 5 to 20 minutes as shown by the DB line, and 20 minutes as shown by the DC line, the oxide film formed becomes too thick. As a result, cracks and peeling of the film tend to occur, and the effect of suppressing metal elution decreases.
一方、加熱温度がＢＣ線で示される９００〜８００°Ｃ
より低い温度では、特にオーステナイト系ステンレス鋼
からなる加熱器管の場合には、５００〜８００°Ｃの温
度域で粒界にクロム炭化物が析出し、その近傍にクロム
欠乏層が生成して鋭敏化が起こり易くなる。なお、５０
０°Ｃ以下の低い温度でもクロム酸化物を主体とする酸
化皮膜を形成することができるが、有効な厚さの酸化皮
膜を得るには長時間の加熱を必要とし実用的ではない。On the other hand, the heating temperature is 900 to 800°C indicated by the BC line.
At lower temperatures, especially in the case of heater tubes made of austenitic stainless steel, chromium carbides precipitate at grain boundaries in the temperature range of 500 to 800°C, and a chromium-depleted layer forms in the vicinity, resulting in sensitization. becomes more likely to occur. In addition, 50
Although it is possible to form an oxide film mainly composed of chromium oxide at temperatures as low as 0° C. or less, it is not practical as it requires long heating to obtain an oxide film with an effective thickness.
また、ＡＦ線で示される１１００℃より高い温度では、
結晶粒が粗大化して機械的性質を損なう。In addition, at temperatures higher than 1100°C indicated by the AF line,
Crystal grains become coarse and mechanical properties are impaired.
上記の条件で、硝酸溶液処理して予め下地皮膜を形成し
たステンレス鋼からなる加熱器管を熱処理すれば、その
表面に効果的に金属の溶出を抑制することができる、ひ
び割れ等のないクロム酸化物を主体とする厚みがおよそ
３００〜１５００人の緻密な酸化皮膜を形成させること
ができる。If a heater tube made of stainless steel that has been treated with a nitric acid solution to form a base film is heat-treated under the above conditions, the chromium oxide surface will be free from cracks, etc., and the elution of metal can be effectively suppressed. It is possible to form a dense oxide film with a thickness of about 300 to 1,500 people, which is mainly composed of substances.
以下、実施例によって本発明を更に説明する。The present invention will be further explained below with reference to Examples.
（実施例）
真空溶解炉を用いて第１表に示すＡ、８２種の合金を溶
製し、熱間鍛造、熱間圧延して厚さ７Ｉの板材とした０
次いで冷間圧延して厚さ２．０＋＋−の供試材を作成し
た。(Example) 82 kinds of alloys A shown in Table 1 were melted using a vacuum melting furnace, hot forged, and hot rolled to form a plate material with a thickness of 7I.
Next, a test material having a thickness of 2.0++- was prepared by cold rolling.
この供試材をエメリー紙（８００番）で研磨し、次いで
硝酸処理を施して表面に下地皮膜を形成さ斌た後、アル
ゴンガス雰囲気中で熱処理（再結晶焼鈍を兼ねた熱処理
）を行い、下地皮膜の上に更にクロム酸化物主体の酸化
皮膜を形成させた。This test material was polished with emery paper (No. 800), then treated with nitric acid to form a base film on the surface, and then heat treated in an argon gas atmosphere (heat treatment that also served as recrystallization annealing). An oxide film consisting mainly of chromium oxide was further formed on the base film.
第２表に硝酸処理条件および熱処理条件を示す。Table 2 shows the nitric acid treatment conditions and heat treatment conditions.
このようにして得られた熱処理後の供試材に対して、酸
化皮膜厚およびＮｉとＣｏの金属溶出量を調べた結果を
、同じ（第２表に示す。The results of examining the oxide film thickness and the amount of metal elution of Ni and Co for the heat-treated test materials obtained in this manner are shown in Table 2.
酸化皮膜厚は！聞＾（Ｉｏｎ Ｍｉｃｒｏ Ｍａｓｓ
Ａｎａｌｙｓｅｒ）を使用し、供試材の表面から板厚方
向にイオンスパッタリング分析により測定した。金属溶
出量は、第２図に示すバッチ式オートクレーブ（１）で
、試験片（２）を２１５°Ｃの脱気した純水（３）中に
白金容器（４）を用いて隔離して浸漬し、１０００時間
試験した。そして、純水中に溶出したＸｉイオン量とＣ
ｏイオン量とを高周波誘導プラズマ発光分光法（ＩＣＰ
）で測定した。What is the oxide film thickness? Listen ^ (Ion Micro Mass
It was measured by ion sputtering analysis from the surface of the sample material in the thickness direction using a 3D analyzer). The amount of metal eluted was determined by immersing the test piece (2) in degassed pure water (3) at 215°C using a platinum container (4) in a batch autoclave (1) shown in Figure 2. and tested for 1000 hours. Then, the amount of Xi ions eluted into pure water and the amount of C
o ion amount and radio frequency induced plasma emission spectroscopy (ICP).
) was measured.
なお、図中（５）は電気炉ヒータ、（６）は温度測定用
熱転対、（７）はガス吹込み口、（８）はガス出口、（
９）は圧力計、Ｏｌは安全弁を示す。In the figure, (5) is the electric furnace heater, (6) is the thermocouple for temperature measurement, (7) is the gas inlet, (8) is the gas outlet, (
9) indicates a pressure gauge, and O1 indicates a safety valve.
第２表より明らかなように、本発明で規定する条件の硝
酸処理、加熱温度、加熱時間および加熱雰囲気で酸化皮
膜を形成させた本発明例（試料ｋｌ〜阻１２）のものは
、いずれも適度な厚さの酸化皮膜が形成され、Ｎ１およ
びＧｏの溶出量が極めて少ない、特に、いずれの試料も
Ｃｏ溶出量がｔｃｐでの検出限界である０、０１−８７
２未満である。As is clear from Table 2, all of the inventive examples (samples k1 to 12) in which oxide films were formed under the conditions of nitric acid treatment, heating temperature, heating time, and heating atmosphere specified in the present invention. An oxide film of appropriate thickness is formed, and the amount of N1 and Go eluted is extremely small.In particular, the amount of Co eluted in all samples is 0,01-87, which is the detection limit in TCP.
Less than 2.
これに対して、比較例の試料Ｎｏ１３と阻１４のように
硝酸処理を施して、本発明で規定する酸素濃度より高い
濃度で熱処理した場合、および試料Ｎｏ１７と８１１１
８、並びに試料漱２５〜隘２８、更には試料毘３１と胤
３２のように本発明で規定する加熱時間より長い時間加
熱した場合、何れも厚い酸化皮膜が得られるものの、そ
の酸化皮膜は厚すぎるために所々でひび割が発生し、隙
間腐食的に材料が腐食されて金属溶出抑制効果が逆に減
少する。また、硝酸処理を施しても試料隘１５と阻１６
のように本発明で規定する酸素濃度より低い濃度で熱処
理した場合、試料麹１９とＮａ２Ｏおよび試料階２９と
逼３０のように低い温度で加熱した場合、何れも得られ
る酸化皮膜が薄すぎて金属溶出抑制効果が小さい、同様
に、試料隘２１と漱２２および試料Ｎα２３と魔２４の
ように硝酸処理を省略するか、または酸濃度が低すぎる
と、酸化皮膜が薄く金属溶出抑制効果が小さい。On the other hand, when samples No. 13 and No. 14 of the comparative example were treated with nitric acid and heat-treated at a concentration higher than the oxygen concentration specified in the present invention, and samples No. 17 and No.
When heated for a longer time than the heating time stipulated in the present invention, such as Samples 25 to 28, Samples 31 and 32, a thick oxide film is obtained in all cases; Because of this, cracks occur in some places, and the material is corroded like crevice corrosion, which actually reduces the metal elution suppressing effect. In addition, even after nitric acid treatment, sample holes 15 and 16
When heat-treated at a concentration lower than the oxygen concentration specified in the present invention, as in Sample Koji 19 and Na2O, and when heated at a low temperature, as in Samples 29 and 30, the resulting oxide film was too thin. The effect of suppressing metal elution is small.Similarly, if the nitric acid treatment is omitted as in samples No. 21 and 22 and samples Nα23 and Ma 24, or if the acid concentration is too low, the oxide film is thin and the effect of suppressing metal elution is small. .
（発明の効果）
以上説明した如く、本発明方法によれば熱処理のみによ
る場合に比べてステンレス鋼からなる加熱器管の表面に
クロム酸化物を主体とするより緻密な酸化皮膜が適正な
厚みで形成されるので、ＮｉやＣｏ等の金属溶出抑制効
果が一段と向上する。従って、例えば沸騰水型原子炉の
給水加熱器管や湿分分離加熱器管に本発明方法を適用す
れば、金属溶出抑制効果の大きい管をつくることができ
る。(Effects of the Invention) As explained above, according to the method of the present invention, a denser oxide film mainly composed of chromium oxide can be formed on the surface of the heater tube made of stainless steel with an appropriate thickness compared to when only heat treatment is used. As a result, the effect of suppressing the elution of metals such as Ni and Co is further improved. Therefore, if the method of the present invention is applied to, for example, a feed water heater tube or a moisture separation heater tube of a boiling water nuclear reactor, it is possible to produce a tube that is highly effective in suppressing metal elution.
第１図は、本発明にかかる熱処理方法で採用する加熱温
度と加熱時間との関係を示すグラフであって、斜線で示
す範囲が本発明の範囲である。
第２図は、実施例で使用した高温水中での金属溶出試験
用オートクレーブを示す概略断面図である。FIG. 1 is a graph showing the relationship between heating temperature and heating time employed in the heat treatment method according to the present invention, and the shaded range is the range of the present invention. FIG. 2 is a schematic cross-sectional view showing an autoclave for testing metal elution in high-temperature water used in Examples.
Claims (1)
らなる加熱器管、又はＣｒを１２〜２０％とＮｉを４０
％以下含有するステンレス鋼からなる加熱器管を、濃度
１０〜４０％の硝酸溶液で処理し、その表面にクロム酸
化物を主体とする酸化皮膜を形成させた後、０．００５
〜０．１ｖｏｌ％の酸素を含む不活性ガス雰囲気中で、
添付第１図に示す点ＡとＢ、ＢとＣ、ＣとＤ、ＤとＥ、
ＥとＦ、ＦとＡをそれぞれ結ぶ直線によって囲まれる領
域内の加熱温度および加熱時間で熱処理し、表面にクロ
ム酸化物を主体とする酸化皮膜を更に形成させることを
特徴とする加熱器管用ステンレス鋼の熱処理方法。Heater tube made of stainless steel containing 12-20% Cr or 12-20% Cr and 40% Ni by weight
A heater tube made of stainless steel containing 0.005% or less is treated with a nitric acid solution with a concentration of 10 to 40% to form an oxide film mainly composed of chromium oxide on its surface.
In an inert gas atmosphere containing ~0.1 vol% oxygen,
Points A and B, B and C, C and D, D and E shown in attached Figure 1,
A stainless steel for heater tubes characterized by being heat treated at a heating temperature and heating time within the area surrounded by straight lines connecting E and F and F and A, respectively, to further form an oxide film mainly composed of chromium oxide on the surface. Method of heat treatment of steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23083788A JPH0280552A (en) | 1988-09-14 | 1988-09-14 | Heat treatment for stainless steel for heater tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23083788A JPH0280552A (en) | 1988-09-14 | 1988-09-14 | Heat treatment for stainless steel for heater tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0280552A true JPH0280552A (en) | 1990-03-20 |
Family
ID=16914059
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23083788A Pending JPH0280552A (en) | 1988-09-14 | 1988-09-14 | Heat treatment for stainless steel for heater tube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0280552A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0661385A4 (en) * | 1991-08-19 | 1994-09-29 | Tadahiro Ohmi | Method for forming oxide film. |
| US6482528B2 (en) | 2000-08-11 | 2002-11-19 | Sumitomo Metal Industries, Inc. | Nickel-base alloy product and method of producing the same |
| US7037390B2 (en) | 2002-02-13 | 2006-05-02 | Sumitomo Metal Industries, Ltd. | Method of heat treatment for Ni-base alloy tube |
| WO2013002314A1 (en) * | 2011-06-29 | 2013-01-03 | 新日鐵住金株式会社 | Method for producing steam generator heat transfer tube for nuclear power plant, and steam generator heat transfer tube |
-
1988
- 1988-09-14 JP JP23083788A patent/JPH0280552A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0661385A4 (en) * | 1991-08-19 | 1994-09-29 | Tadahiro Ohmi | Method for forming oxide film. |
| US6482528B2 (en) | 2000-08-11 | 2002-11-19 | Sumitomo Metal Industries, Inc. | Nickel-base alloy product and method of producing the same |
| US7037390B2 (en) | 2002-02-13 | 2006-05-02 | Sumitomo Metal Industries, Ltd. | Method of heat treatment for Ni-base alloy tube |
| WO2013002314A1 (en) * | 2011-06-29 | 2013-01-03 | 新日鐵住金株式会社 | Method for producing steam generator heat transfer tube for nuclear power plant, and steam generator heat transfer tube |
| JP5218704B1 (en) * | 2011-06-29 | 2013-06-26 | 新日鐵住金株式会社 | Method of manufacturing steam generator heat transfer tube for nuclear power plant and steam generator heat transfer tube |
| CN103635973A (en) * | 2011-06-29 | 2014-03-12 | 新日铁住金株式会社 | Method for producing steam generator heat transfer tube for nuclear power plant, and steam generator heat transfer tube |
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