JPH01316418A - Production of austenitic stainless steel exhibiting excellent integranular corrosion resistance in nitric acid solution - Google Patents
Production of austenitic stainless steel exhibiting excellent integranular corrosion resistance in nitric acid solutionInfo
- Publication number
- JPH01316418A JPH01316418A JP14700888A JP14700888A JPH01316418A JP H01316418 A JPH01316418 A JP H01316418A JP 14700888 A JP14700888 A JP 14700888A JP 14700888 A JP14700888 A JP 14700888A JP H01316418 A JPH01316418 A JP H01316418A
- Authority
- JP
- Japan
- Prior art keywords
- nitric acid
- stainless steel
- austenitic stainless
- ions
- steel
- 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
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 229910017604 nitric acid Inorganic materials 0.000 title claims abstract description 32
- 238000005260 corrosion Methods 0.000 title claims abstract description 28
- 230000007797 corrosion Effects 0.000 title claims abstract description 28
- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 230000001747 exhibiting effect Effects 0.000 title 1
- 238000001816 cooling Methods 0.000 claims abstract description 32
- 239000010959 steel Substances 0.000 claims abstract description 19
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 18
- 239000012535 impurity Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 abstract description 19
- 150000002500 ions Chemical class 0.000 abstract description 18
- 230000001590 oxidative effect Effects 0.000 abstract description 8
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 7
- 239000003758 nuclear fuel Substances 0.000 abstract description 3
- 230000007774 longterm Effects 0.000 abstract 1
- 238000011268 retreatment Methods 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 20
- 239000011651 chromium Substances 0.000 description 13
- 238000012360 testing method Methods 0.000 description 13
- 229910001220 stainless steel Inorganic materials 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 229910052804 chromium Inorganic materials 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 238000001556 precipitation Methods 0.000 description 7
- 238000009835 boiling Methods 0.000 description 6
- -1 nitric acid Chemical class 0.000 description 5
- 239000010935 stainless steel Substances 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 239000011574 phosphorus Substances 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- UFGZSIPAQKLCGR-UHFFFAOYSA-N chromium carbide Chemical compound [Cr]#C[Cr]C#[Cr] UFGZSIPAQKLCGR-UHFFFAOYSA-N 0.000 description 3
- 238000012733 comparative method Methods 0.000 description 3
- 230000002950 deficient Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 229910003470 tongbaite Inorganic materials 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000003018 phosphorus compounds Chemical class 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000012958 reprocessing Methods 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 229910000365 copper sulfate Inorganic materials 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- ing And Chemical Polishing (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、硝酸溶液中あるいはＣｒ’＋イオンやＲｕｎ
＋イオンのような酸化性イオンを含有する硝酸溶液中で
すぐれた耐粒界腐食性を示すオーステナイト系ステンレ
ス鋼の製造法に関するものである。[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to nitric acid solution or Cr'+ ion or Run
The present invention relates to a method for producing austenitic stainless steel that exhibits excellent intergranular corrosion resistance in nitric acid solutions containing oxidizing ions such as + ions.
［従来の技術］
オーステナイト系ステンレス鋼は、硝酸のような強い酸
化性の酸に対して非常な耐性を示すことから、硝酸の製
造装置、硝酸を使用する装置、核燃料再処理装置などの
＃ｎ設素材に使用されている。[Prior Art] Austenitic stainless steel is extremely resistant to strong oxidizing acids such as nitric acid, and is therefore used in nitric acid manufacturing equipment, equipment using nitric acid, nuclear fuel reprocessing equipment, etc. Used for construction materials.
かかる環境で使用されるオーステナイト系ステンレス鋼
は、１８〜２０％Ｃｒ、 ８〜１０．５％Ｎｉステンレ
ス鋼（ＳＩＪＳ ３０４）、特公昭５７−３７６６９号
公報で紹介されているような２．５〜５％Ｓｉ、 １５
〜２０％Ｃｒ、１０〜２２％Ｎｉに少量の７１’ａ、
Ｚｒ、 Ｎｂを選択的に含有させた濃硝酸用ステンレス
鋼などがある。しかしながらこのようなオーステナイト
系ステンレス鋼は常温の硝酸溶液に対して優れた耐酸性
を示すが、硝酸溶液が加熱されて発生したＮＯｘがステ
ンレス鋼表面の不動態皮膜を破壊し、その部分が優先的
に腐食される問題があった。また温度４００〜８５０℃
の間で長時間加熱と冷却が繰返される環境で使用される
オーステナイト系ステンレス鋼は、クロム炭化物が結晶
粒界に沿って生成することによって粒界近傍のＣｒ濃度
が減少し、その部分の耐食性が劣化し、ＮＯＸが存在す
る環境においては−層腐食される問題があった。こうし
た問題の原因は、本発明者らの実験によると、固溶化熱
処理にあった。すなわち固溶化熱処理法は通常１０１Ｏ
〜１１５０℃の温度に加熱した後水冷するプロセスで行
なわれているが、この冷却速度（常温までの平均冷却速
度）が２０℃１秒以下の緩冷却のため、結晶粒界にクロ
ム炭化物と鋼中不純物元素として含まれるＰの化合物が
析出されることに原因があった。Austenitic stainless steels used in such environments include 18-20% Cr, 8-10.5% Ni stainless steel (SIJS 304), and 2.5-20% Ni stainless steel as introduced in Japanese Patent Publication No. 57-37669. 5%Si, 15
~20% Cr, 10~22% Ni with a small amount of 71'a,
There are stainless steels for use in concentrated nitric acid that selectively contain Zr and Nb. However, although such austenitic stainless steel exhibits excellent acid resistance against nitric acid solution at room temperature, the NOx generated when the nitric acid solution is heated destroys the passive film on the stainless steel surface, and that part becomes preferential. There was a problem with corrosion. Also the temperature is 400~850℃
In austenitic stainless steel, which is used in an environment where heating and cooling are repeated for long periods of time, chromium carbides are generated along grain boundaries, reducing the Cr concentration near the grain boundaries and reducing the corrosion resistance of that area. In an environment where NOx is present, there is a problem that the layer is corroded. According to experiments conducted by the present inventors, the cause of these problems was the solution heat treatment. In other words, the solution heat treatment method usually uses 101O
It is carried out by a process of heating to a temperature of ~1150°C and then cooling with water, but because this cooling rate (average cooling rate to room temperature) is slow cooling of less than 1 second at 20°C, chromium carbide and steel are formed at grain boundaries. The cause was that a compound of P, which is included as an intermediate impurity element, was precipitated.
［発明が解決しようとする課題］
本発明は、硝酸および酸化性イオンを含有する硝酸溶液
中で優れた耐粒界腐食性を有し、硝酸製造装置、核燃料
再処理装置など硝酸溶液に晒される環境の構造用素材と
して長期間使用できる、オーステティ１−系ステンレス
鋼の製造方法を開示するものである。[Problems to be Solved by the Invention] The present invention has excellent intergranular corrosion resistance in a nitric acid solution containing nitric acid and oxidizing ions, and has excellent resistance to intergranular corrosion in a nitric acid solution containing nitric acid and oxidizing ions. The present invention discloses a method for manufacturing Austety 1-stainless steel, which can be used as an environmental structural material for a long period of time.
［課題を解決するための手段および作用］本発明者らは
、硝酸溶液中あるいはＣｒ＠“イオンやＲｕｎ＋イオン
のような酸化性イオンを含有する硝酸溶液中で優れた耐
粒界腐食性を示すオーステナイト系ステンレス鋼の製造
法を追求することを目的にして多くの実＃Ｊを試みた結
果、固溶化熱処理時の冷却条件を制御することによって
目的のオーステティ１〜系ステンレス鋼が鋳造できるこ
とを知見した０本発明はこの知見に基づくもので。[Means and effects for solving the problem] The present inventors have demonstrated excellent intergranular corrosion resistance in a nitric acid solution or in a nitric acid solution containing oxidizing ions such as Cr@" ions and Run+ ions. As a result of trying many actual #J with the aim of pursuing a manufacturing method for austenitic stainless steel, it was discovered that the desired austenitic stainless steel could be cast by controlling the cooling conditions during solution heat treatment. The present invention is based on this knowledge.
その要旨は、鋼中不純物元素のＰを０．０４％以下含有
するオーステナイト系ステンレス鋼を１０００℃以上の
温度で２分間以上保定する加熱処理を施した後、該温度
から５００℃までの温度間を４０℃／秒以上の冷却速度
で急冷処理するオーステナイト系ステンレス鋼の製造法
である。The gist of this is that austenitic stainless steel containing 0.04% or less of P, an impurity element in the steel, is heat-treated for at least 2 minutes at a temperature of 1000°C or higher, and then heated at a temperature between that temperature and 500°C. This is a method for producing austenitic stainless steel in which austenitic stainless steel is rapidly cooled at a cooling rate of 40° C./second or higher.
以下１本発明について詳細に説明する。The present invention will be explained in detail below.
転炉、電気炉など通常の溶解炉で溶製して鋼中のＰを０
．０４％以下に抑制したオーステナイト系ステンレス鋼
の溶鋼を、造塊−分塊法あるいは連続鋳造法を経て鋼片
に製造する０本発明においてＰは本発明の目的を阻害す
る有害な元素として特にその含有量を規制した。鋼片は
、さらに熱間加工を施して棒、管、形鋼、鋼板などの各
種の形状に製造される。このようにして熱間加工されあ
るいはさらに突合せ溶接されたオーステナイト系ステン
レス鋼は１０００℃以上の温度に加熱する。この加熱処
理は、熱間圧延などの加工に伴う加工組織を再結晶化し
て整粒組織とする共に、熱間加工中およびその後の冷却
途中で析出するクロｌ−炭化物およびリン化合物を分解
し、再固溶化を計るものである。このような効果は、第
１図に加熱温度と加熱時間の関係で粒界リン化物の析出
状況を示すように、 ｔｏｏｏ℃を越える高い温度でか
つ２分間以上の加熱時間で粒界リン化物が完全に固溶さ
れる。The P content in steel is reduced to 0 by melting it in a normal melting furnace such as a converter or electric furnace.
．． In the present invention, P is a harmful element that obstructs the purpose of the present invention, in which molten steel of austenitic stainless steel whose content is suppressed to 04% or less is manufactured into steel slabs through an ingot-blooding method or a continuous casting method. The content was regulated. The steel pieces are further hot-worked to be manufactured into various shapes such as rods, pipes, sections, and steel plates. The austenitic stainless steel hot-worked or butt-welded in this way is heated to a temperature of 1000° C. or more. This heat treatment recrystallizes the processed structure resulting from processing such as hot rolling to form a grain-sized structure, and also decomposes chloro-carbide and phosphorus compounds that precipitate during hot processing and subsequent cooling. This measures re-solid solutionization. This effect is due to the fact that grain boundary phosphides are precipitated at temperatures exceeding 100°C and heating times of 2 minutes or more, as shown in Figure 1, which shows the precipitation of grain boundary phosphides in relation to heating temperature and heating time. Completely dissolved.
その固溶化には１０００℃以上の温度で目的を達するこ
とができるが、固溶化温度が高過ぎると再結晶粒が粗大
化して混合粒組織を呈し、鋼の耐力および引張強さを著
しく低下し実用性を失う傾向にある。したがってこのよ
うな問題から１１５０℃以下の温度で１０〜２０分間の
加熱時間が好ましい。The purpose of solid solution treatment can be achieved at a temperature of 1000°C or higher, but if the solution temperature is too high, the recrystallized grains will become coarse and have a mixed grain structure, which will significantly reduce the yield strength and tensile strength of the steel. It tends to lose its practicality. Therefore, in view of such problems, it is preferable to heat the film at a temperature of 1150° C. or lower and for a heating time of 10 to 20 minutes.
このような加熱処理を終えたオーステナイト系ステンレ
ス鋼は、その加熱温度から５００℃までの温度間を４０
℃１秒（平均冷却速度）以上の速い速度で冷却する。こ
の冷却処理は、第２図に０．０２９％のリンを含有する
ＳＵＳ ３０４鋼の、加熱温度１０００℃以上から５０
０℃までの冷却速度と粒界析出リン化物有無状況の関係
を示すように、粒界リン化物析出を防止する上で必須条
件である。従来１粒界クロム炭化物析出に伴う粒界クロ
ム欠乏層の生成を防止する観点から、工業的には１００
０℃から５００℃までの冷却速度が５〜２０℃１秒であ
れば十分とされている。すなわちＳＯ５３０４鋼（Ｃ量
０．０５ｗｔ％）の厚さ２ｍｍ、幅１２００＋＋ｓ＋の
冷間圧延コイルは１０６０℃で約２分間の最終連続焼鈍
処理を施した後、気水噴霧冷却（冷却速度１０〜１５℃
１秒）が行なわれる。Austenitic stainless steel that has undergone such heat treatment can be heated for 40 degrees between the heating temperature and 500°C.
Cool at a fast rate of 1 second (average cooling rate) or more. This cooling treatment is performed for SUS 304 steel containing 0.029% phosphorus from a heating temperature of 1000°C or higher to 50°C as shown in Figure 2.
As shown in the relationship between the cooling rate to 0° C. and the presence or absence of grain boundary phosphides, this is an essential condition for preventing grain boundary phosphide precipitation. Conventionally, from the viewpoint of preventing the formation of a grain boundary chromium-depleted layer due to grain boundary chromium carbide precipitation, 100
It is said that a cooling rate of 5 to 20°C for 1 second from 0°C to 500°C is sufficient. That is, a cold-rolled coil of SO5304 steel (C content 0.05 wt%) with a thickness of 2 mm and a width of 1200++s+ is subjected to a final continuous annealing treatment at 1060°C for about 2 minutes, and then air-water spray cooling (cooling rate 10 to 15%). ℃
1 second) is performed.
かかる１０〜１５℃１秒程度の冷却速度で処理したＳＯ
３３０４は、ＪＩＳで規定される６５％硝酸試験（ＪＩ
ＳＧ ０５７３）、 １０％しゆう酸エッチ試験（ＪＩ
Ｓ Ｇ ０５７１）等のすべての粒界試験に合格する。SO treated at a cooling rate of about 1 second at 10 to 15°C
3304 is the 65% nitric acid test specified by JIS (JI
SG 0573), 10% oxalic acid etch test (JI
Pass all grain boundary tests such as SG 0571).
しかしながら１本発明が対象のＣｒ″１イオンなどの酸
化性イオンを含有する硝酸溶液中では、ｌＯ〜１５℃／
秒程度の冷却速度で処理したステンレス鋼はすべて著し
い粒界腐食を発生する。However, in a nitric acid solution containing oxidizing ions such as Cr''1 ions, which is the object of the present invention,
All stainless steels treated at cooling rates on the order of seconds experience significant intergranular corrosion.
すなわち通常の冷却速度で処理されたステンレス鋼は、
粒界クロム欠乏層に起因する粒界腐食は発生しないが、
鋼中リンの化合物の粒界析出に起因する粒界腐食感受性
を有する。したがって粒界リン化合物析出を防止するた
めには、４０℃／秒以上の冷却速度で処理する必要があ
る。In other words, stainless steel processed at normal cooling rates is
Although intergranular corrosion due to grain boundary chromium-deficient layer does not occur,
It has susceptibility to intergranular corrosion due to intergranular precipitation of phosphorus compounds in steel. Therefore, in order to prevent grain boundary phosphorus compound precipitation, it is necessary to perform the treatment at a cooling rate of 40° C./sec or more.
このような冷却速度は従来の冷却速度に較べて著しく速
いが、オーステナイト系ステンレス鋼を水中に投入冷却
するかあるいは鋼全面に十分な注水冷却を行なうことに
よって容易に得られる。また高速冷却速度の終了温度を
５００℃にした理由は、５００℃以下の低い温度ではク
ロム炭化物の粒界析出が無視出来る程度に緩慢になり、
粒界リン化物の析出がリン自体が置換型固溶元素である
ため粒界への拡散速度も著しく低下し、本発明の目的が
損われることがない。Such a cooling rate is significantly faster than conventional cooling rates, but can be easily obtained by cooling the austenitic stainless steel by immersing it in water or cooling the entire surface of the steel with sufficient water. In addition, the reason why the end temperature of the fast cooling rate was set at 500°C is that at low temperatures below 500°C, grain boundary precipitation of chromium carbides becomes negligible and slow.
Since phosphorus itself is a substitutional solid solution element in the precipitation of grain boundary phosphides, the diffusion rate to the grain boundaries is also significantly reduced, so that the object of the present invention is not impaired.
このようにして５００℃の温度に冷却されたオーステナ
イト系ステンレス鋼は、常温まで任意の速度で冷却され
る。The austenitic stainless steel thus cooled to a temperature of 500° C. is cooled to room temperature at an arbitrary rate.
［実施例］ 次に本発明の実施例について説明する。[Example] Next, examples of the present invention will be described.
実施例１
第１表は腐食試験用試料としてＰを０ 、０１％を含有
するＳＯ９：１１１４．ｔ’；よびＳＯ８：１Ｉ（ｉ（
厚さ２ｍ＋＋＋）を、１（）５０℃で３分間加熱した時
の８に／ＱのＣｒ＠＋イオンを含有する沸騰５Ｎ硝酸溶
液試験および沸ａ６５％硝酸試験（ＪＩＳ Ｇ ０５７
３）による粒界腐食性の冷却速度ついての実施例を示す
、固溶化熱処理後板表面に冷却水を直接吹付け４０℃７
秒以上の冷却速度を確保した本発明は、いずれの粒界腐
食試験においても粒界腐食は観察されないが、比較法の
ように４０℃／秒未満の気水噴霧による冷却速度では沸
騰６５％硝酸試験（ＪＩＳ Ｇ ０５７３）によれば問
題ないが、 Ｃｒ’＋イオンを含有する沸騰５Ｎ硝酸溶
液試験では著しい粒界腐食を発生する。Example 1 Table 1 shows SO9:1114.0 containing 0.01% P as a corrosion test sample. t'; and SO8:1I(i(
A boiling 5N nitric acid solution test containing 8/Q Cr@+ ions and a boiling a65% nitric acid test (JIS G 057
3) shows an example of the cooling rate of intergranular corrosion. Cooling water was directly sprayed onto the plate surface after solution heat treatment at 40°C 7.
In the present invention, which has secured a cooling rate of 2 seconds or more, intergranular corrosion is not observed in any intergranular corrosion tests, but when the cooling rate by air water spray is less than 40°C/second as in the comparative method, boiling 65% nitric acid According to the test (JIS G 0573), there was no problem, but in the boiling 5N nitric acid solution test containing Cr'+ ions, significant intergranular corrosion occurred.
実施例２
第２表はＰを０．０２％含有するＳＯ３３０４，ＳＯ３
３１６およびＳＯ５３１０の３鋼種の４インチスケ−ジ
ュール８０の鋼管について、１０５０℃Ｘ １０分の固
溶比熱処理後鋼管内面に注水しその冷却速度を４０℃／
秒以上にした本発明法と、比較法で鋼管全体を水中に焼
入れした場合のそれぞれについての管内面の８ｇ／ Ｑ
のＣｒ’＋イオンを含有する沸１１１５Ｎ硝酸溶液中お
よび硫酸・硫酸銅試験溶液中における粒界腐食試験結果
をしめす、比較法の鋼管全体を水中に焼入れする方法で
は管内面では粒界クロム炭化物析出処理にともなう粒界
クロム欠乏層の生成に起因する粒界腐食性は防止されて
いるが１粒界析出リン化物に起因する粒界腐食を発生す
る。Example 2 Table 2 shows SO3304, SO3 containing 0.02% P.
For 4-inch schedule 80 steel pipes of three steel types, 316 and SO5310, after solid solution specific heat treatment at 1050°C for 10 minutes, water was poured into the inner surface of the steel pipe and the cooling rate was increased to 40°C/
8g/Q of the inner surface of the pipe for both the method of the present invention in which the temperature was quenched for more than 1 second, and the comparative method in which the entire steel pipe was quenched in water.
This shows the results of intergranular corrosion tests in boiling 1115N nitric acid solution containing Cr'+ ions and in sulfuric acid/copper sulfate test solution.In the comparative method in which the entire steel pipe is quenched in water, grain boundary chromium carbide precipitates on the inner surface of the pipe. Although intergranular corrosion caused by the formation of grain boundary chromium-deficient layers accompanying treatment is prevented, intergranular corrosion occurs due to phosphides precipitated at grain boundaries.
これに対して、本発明のごとく鋼管内面に注水し、その
冷却速度を４０℃７秒以上にした場合、粒界クロム欠乏
層の生成に起因する粒界腐食はもちろんのこと、粒界祈
出リン化物に起因する粒界腐食も全く発生しない。On the other hand, when water is injected into the inner surface of a steel pipe and the cooling rate is set to 40°C for 7 seconds or more as in the present invention, not only intergranular corrosion due to the formation of a grain boundary chromium-deficient layer but also intergranular corrosion occurs. Intergranular corrosion caused by phosphides does not occur at all.
［発明の効果］
以上述べた如く１本発明法で得られたオーステナイト系
ステンレス鋼は、硝酸および酸化性イオンを含有する硝
酸溶液中で優れた耐粒界腐食性を有するため、硝酸製造
装置や核燃料再処理設備など、硝酸溶液に晒される環境
の構造用素材として長期間使用できる。[Effects of the Invention] As described above, the austenitic stainless steel obtained by the method of the present invention has excellent intergranular corrosion resistance in nitric acid and nitric acid solutions containing oxidizing ions, and therefore is suitable for use in nitric acid production equipment and It can be used for long periods as a structural material in environments exposed to nitric acid solutions, such as in nuclear fuel reprocessing facilities.
第１図は粒界析出リン化物を有する腐食試験用試料ＳＯ
３３０４鋼の熱処理に伴う粒界析出リン化物の分解の加
熱温度と加熱時間依存性を示す。
第２図は０．０２９％のリンを含有する腐食試験用試料
ＳＯ３３０４の、 １０５０℃から５００℃までの冷却
速度と粒界祈出リン化物の有無および８ｇ／ Ｉ！のＣ
ｒ＠＋イオンを含有する沸騰５Ｎ硝酸溶液試験による粒
界腐食の関係を示す図
である。
特許出願人 新Ｆ１本製鑵株式会社Figure 1 shows corrosion test sample SO with grain boundary precipitated phosphide.
This figure shows the heating temperature and heating time dependence of the decomposition of grain boundary precipitated phosphides during heat treatment of 3304 steel. Figure 2 shows the cooling rate from 1050°C to 500°C, presence or absence of grain boundary phosphide, and 8g/I! of corrosion test sample SO3304 containing 0.029% phosphorus. C of
FIG. 2 is a diagram showing the intergranular corrosion relationship in a boiling 5N nitric acid solution test containing r@+ ions. Patent applicant: Shin F1 Honsei Co., Ltd.
Claims (1)
ナイト系ステンレス鋼を１０００℃以上の濃度で２分間
以上保定する加熱処理を施した後、該加熱温度から５０
０℃までの温度間を４０℃／秒以上の冷却速度で急冷処
理することを特徴とする硝酸溶液中で優れた耐粒界腐食
性を示すオーステナイト系ステンレス鋼の製造法After heat-treating austenitic stainless steel containing 0.04% or less of P, an impurity element in steel, at a concentration of 1000°C or higher for 2 minutes or more,
A method for producing austenitic stainless steel that exhibits excellent intergranular corrosion resistance in a nitric acid solution, characterized by rapid cooling treatment at a cooling rate of 40°C/sec or more between temperatures down to 0°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14700888A JPH01316418A (en) | 1988-06-16 | 1988-06-16 | Production of austenitic stainless steel exhibiting excellent integranular corrosion resistance in nitric acid solution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14700888A JPH01316418A (en) | 1988-06-16 | 1988-06-16 | Production of austenitic stainless steel exhibiting excellent integranular corrosion resistance in nitric acid solution |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01316418A true JPH01316418A (en) | 1989-12-21 |
Family
ID=15420472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14700888A Pending JPH01316418A (en) | 1988-06-16 | 1988-06-16 | Production of austenitic stainless steel exhibiting excellent integranular corrosion resistance in nitric acid solution |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01316418A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2112237A1 (en) | 2008-04-21 | 2009-10-28 | Secretary, Department Of Atomic Energy | Development of a very high resistance to sensitization in austenitic stainless steel through special heat treatment resulting in grain boundary microstructural modification |
| WO2013018628A1 (en) * | 2011-07-29 | 2013-02-07 | 新日鐵住金株式会社 | Method for producing austenitic stainless steel |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55107729A (en) * | 1979-02-13 | 1980-08-19 | Sumitomo Metal Ind Ltd | Solution-treating method for austenitic stainless steel |
| JPS62287051A (en) * | 1986-06-03 | 1987-12-12 | Kobe Steel Ltd | Austenitic stainless steel excellent in resistance to intergranular stress corrosion cracking and intergranular corrosion resistance |
-
1988
- 1988-06-16 JP JP14700888A patent/JPH01316418A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55107729A (en) * | 1979-02-13 | 1980-08-19 | Sumitomo Metal Ind Ltd | Solution-treating method for austenitic stainless steel |
| JPS62287051A (en) * | 1986-06-03 | 1987-12-12 | Kobe Steel Ltd | Austenitic stainless steel excellent in resistance to intergranular stress corrosion cracking and intergranular corrosion resistance |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2112237A1 (en) | 2008-04-21 | 2009-10-28 | Secretary, Department Of Atomic Energy | Development of a very high resistance to sensitization in austenitic stainless steel through special heat treatment resulting in grain boundary microstructural modification |
| WO2013018628A1 (en) * | 2011-07-29 | 2013-02-07 | 新日鐵住金株式会社 | Method for producing austenitic stainless steel |
| JP5418734B2 (en) * | 2011-07-29 | 2014-02-19 | 新日鐵住金株式会社 | Method for producing austenitic stainless steel |
| CN103826766A (en) * | 2011-07-29 | 2014-05-28 | 新日铁住金株式会社 | Method for producing austenitic stainless steel |
| KR101495483B1 (en) * | 2011-07-29 | 2015-02-24 | 신닛테츠스미킨 카부시키카이샤 | Method for producing austenitic stainless steel |
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