JPH0674470B2 - Structural material for nitric acid plant - Google Patents
Structural material for nitric acid plantInfo
- Publication number
- JPH0674470B2 JPH0674470B2 JP1114789A JP11478989A JPH0674470B2 JP H0674470 B2 JPH0674470 B2 JP H0674470B2 JP 1114789 A JP1114789 A JP 1114789A JP 11478989 A JP11478989 A JP 11478989A JP H0674470 B2 JPH0674470 B2 JP H0674470B2
- Authority
- JP
- Japan
- Prior art keywords
- nitric acid
- concentration
- azeotropic
- azeotropic concentration
- scc
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、ジルコニウム基合金、特に硝酸製造プラント
のような共沸濃度以上の高濃度の硝酸を取り扱うプラン
ト用構造材として適した耐応力腐食割れ性に優れたジル
コニウム基合金に関する。TECHNICAL FIELD The present invention relates to a zirconium-based alloy, in particular, stress corrosion resistance suitable as a structural material for a plant that handles a high concentration of nitric acid having an azeotropic concentration or higher, such as a nitric acid production plant. The present invention relates to a zirconium-based alloy having excellent crackability.
（従来の技術） ジルコニウム（以下「Zr」とも云う）は、硝酸環境下で
耐全面腐食性は非常に優れていることが良く知られてい
る。(Prior Art) It is well known that zirconium (hereinafter also referred to as “Zr”) has very excellent general corrosion resistance in a nitric acid environment.
硝酸は、比重1.42（約70％）で共沸点を持つ。沸点はこ
の共沸点で極大値である123℃となる。これより低濃度
側では沸点は水の沸点である100℃まで下り、一方、高
濃度側では86℃まで下がる。硝酸はこのように共沸点を
持つので、通常の蒸留による濃縮では共沸濃度までしか
濃縮できない。そのため、共沸濃度以上の硝酸を製造し
ている硝酸製造プラントにおいては、硝酸による脱水等
の特別な方法がとられている。Nitric acid has an azeotropic point with a specific gravity of 1.42 (about 70%). The boiling point is 123 ° C, which is the maximum value of this azeotropic point. On the low concentration side, the boiling point drops to 100 ° C, which is the boiling point of water, and on the high concentration side, it drops to 86 ° C. Since nitric acid has an azeotropic point in this way, it can be concentrated to an azeotropic concentration only by ordinary distillation. Therefore, in a nitric acid production plant that produces nitric acid having an azeotropic concentration or higher, a special method such as dehydration with nitric acid is used.
そこで、硝酸製造プラントにおいては常に共沸濃度以上
の硝酸を扱うことになり、現状ではステンレス鋼などを
構造材として使用したり、合金材を頻繁に取り替えなが
ら使用している。Therefore, nitric acid manufacturing plants always handle nitric acid having an azeotropic concentration or more, and currently, stainless steel or the like is used as a structural material or alloy material is frequently replaced.
（発明が解決しようとする課題） 前記したように、硝酸は共沸点を持つが、この共沸濃度
以下と共沸濃度以上では腐食性は全く異なり、異質の腐
食挙動を示す。(Problems to be Solved by the Invention) As described above, nitric acid has an azeotropic point, but the corrosiveness is completely different below this azeotropic concentration and above the azeotropic concentration, and shows a heterogeneous corrosion behavior.
すなわち、Zrは硝酸中では耐食性が優れていると報告さ
れているが、共沸濃度以上の硝酸中では、強制的に電位
を負荷しなくても応力腐食割れ（SCC）が発生すること
が報告されている（Ｔ−L,Yau:Corrosion 39（1983）p.
167）。この報告によれば、工業用純Zrである702（AST
M）は70％HNO3中ではSCCを発生しないが、80％以上では
SCCを発生した。通常、温度が低くなると耐食性は向上
するが、共沸濃度以上では常温付近でもSCCを発生する
ようになる。That is, although Zr is reported to have excellent corrosion resistance in nitric acid, it has been reported that stress corrosion cracking (SCC) occurs in nitric acid at an azeotropic concentration or higher without forcibly applying a potential. (T-L, Yau: Corrosion 39 (1983) p.
167). According to this report, pure industrial Zr 702 (AST
M) does not generate SCC in 70% HNO 3 , but above 80%
SCC has occurred. Generally, when the temperature is low, the corrosion resistance is improved, but when the temperature is higher than the azeotropic concentration, SCC is generated even at around room temperature.
従来より、共沸濃度以下の硝酸中における耐食性を向上
させるため、ZrにTiを添加する方法が提案されている
（特開昭62−222037号）が、共沸濃度以上の硝酸中にお
けるSCCに関して何ら示唆するところはない。しかも、
上述の提案は、原子力燃料の再処理を目的としたプラン
トの構造材としてであり、このようなプラントでは共沸
濃度以上の硝酸を使うことはない。また、前述のように
共沸濃度以下の硝酸が濃縮されて共沸濃度以上の硝酸に
なることはないので、本発明が規定しているような環境
とは全く異なる環境である。Conventionally, in order to improve the corrosion resistance in nitric acid below the azeotropic concentration, a method of adding Ti to Zr has been proposed (JP-A-62-222037), but regarding SCC in nitric acid above the azeotropic concentration There is no suggestion. Moreover,
The above proposal is as a structural material of a plant for the purpose of reprocessing nuclear fuel, and nitric acid having an azeotropic concentration or higher is not used in such a plant. Further, as described above, nitric acid having an azeotropic concentration or less is not concentrated to form nitric acid having an azeotropic concentration or more, so that the environment is completely different from the environment defined by the present invention.
また、耐硝酸性が優れているといわれるステンレス鋼に
おいても、共沸濃度以下では十分使用に耐えるが、共沸
濃度以上では耐食量が著しく大きくなり、通常のステン
レス鋼では使用できなくなる。この場合、Si含有量を高
める方法などがとられているが、腐食の程度は大きく一
定期間ごとの機器の交換が必要である。一方、非鉄金属
の代表的な材料はTiであるが、Tiは共沸濃度以上の硝酸
である発煙硝酸中で発火、爆発することが報告されてい
る。また、共沸濃度以下では腐食が大きくなる。Further, stainless steel, which is said to have excellent nitric acid resistance, can withstand sufficient use below the azeotropic concentration, but above the azeotropic concentration, the corrosion resistance becomes remarkably large, and it cannot be used with ordinary stainless steel. In this case, methods such as increasing the Si content are taken, but the degree of corrosion is large and it is necessary to replace the equipment at regular intervals. On the other hand, a typical material of non-ferrous metal is Ti, which has been reported to ignite and explode in fuming nitric acid, which is nitric acid having an azeotropic concentration or higher. Further, if the concentration is lower than the azeotropic concentration, the corrosion becomes large.
以上のように、共沸濃度以上の硝酸は腐食性が厳しく、
この環境で用いる適切な構造材が従来はなかった。ま
た、Zrは耐全面腐食性に優れるが硝酸の共沸濃度以上で
SCCを発生するため、その使用が考えられることはなか
った。As mentioned above, nitric acid with an azeotropic concentration or higher is severely corrosive,
There has been no suitable structural material for this environment. Also, Zr is excellent in general corrosion resistance, but it does not exceed the azeotropic concentration of nitric acid.
Its use was never considered because it causes SCC.
ここに、本発明は、共沸濃度以上の硝酸中で耐食性、特
に耐応力腐食割れ性の優れた合金材料を提供することを
目的としている。An object of the present invention is to provide an alloy material having excellent corrosion resistance, particularly stress corrosion cracking resistance, in nitric acid having an azeotropic concentration or higher.
（課題を解決するための手段） 上記目的を達成するため、本発明者らはZr基合金に着目
し、Zrとは全率固溶型の金属であり金属間化合物等を生
成しないTiを合金元素として添加し、Tiの添加量を種々
変化させ、SCCの試験を行った結果、適正成分系を見出
して完成したものである。(Means for Solving the Problems) In order to achieve the above object, the present inventors have focused on a Zr-based alloy, and Zr is an alloy of Ti that does not form an intermetallic compound or the like, which is a solid solution type metal. It was added as an element, the amount of Ti added was changed variously, and the SCC test was conducted. As a result, a suitable component system was found and completed.
本発明の要旨とするところは、重量％で Ti:5.0〜30％、 酸素:0.2％以下、 残部Zrおよび不可避不純物 ただし、不純物として、Fe:0.3％以下、Cr:0.1％以下、
N:0.03％以下、 H:0.01％以下にそれぞれ制限する、 より成る合金組成を有し、耐応力腐食割れ性に優れた、
共沸濃度を超えた70％超の濃度の硝酸溶液を取り扱うプ
ラント用構造材である。The gist of the present invention is that Ti: 5.0 to 30% by weight, oxygen: 0.2% or less, balance Zr and unavoidable impurities However, as impurities, Fe: 0.3% or less, Cr: 0.1% or less,
N: 0.03% or less, H: 0.01% or less, respectively.
It is a structural material for plants that handles nitric acid solutions with a concentration exceeding 70%, which exceeds the azeotropic concentration.
（作用） 本発明において、合金成分組成範囲を限定した理由は次
のとおりである。なお、本明細書において「％」は特に
指示しない限りいずれも「重量％」である。(Function) In the present invention, the reason for limiting the alloy component composition range is as follows. In the present specification, “%” is “% by weight” unless otherwise specified.
Ti:共沸濃度以上におけるZrのSCCを防止するため、5.0
％以上を添加する。望ましくは10％以上添加する。余り
多量の添加を行うと曲げ性が劣化するので上限は30％と
する。Ti: To prevent SCC of Zr at azeotropic concentration or higher, 5.0
% Or more is added. Desirably 10% or more is added. If too much is added, bendability deteriorates, so the upper limit is 30%.
FeおよびCr:Zrとの金属間化合物の量を増大させ 曲げ性を劣化させるのでそれぞれFe:0.3％以下、 Cr:0.1％以下とする。Since Fe and Cr: Zr increase the amount of intermetallic compounds and deteriorate the bendability, Fe: 0.3% or less and Cr: 0.1% or less, respectively.
酸素：強度向上のため添加する。しかし、0.2％を越え
ると曲げ性が悪くなるので上限を0.2％とする。Oxygen: added to improve strength. However, if it exceeds 0.2%, the bendability deteriorates, so the upper limit is made 0.2%.
N:曲げ性能が劣化するため上限は0.05％とする。N: Bending performance deteriorates, so the upper limit is made 0.05%.
H:水素化物の形成による曲げ性能の低下がみられるた
め、0.01％以下とする。H: Since bending performance is deteriorated due to the formation of hydride, the content is made 0.01% or less.
次に、本発明の作用効果を実施例により具体的に説明す
る。Next, the function and effect of the present invention will be specifically described by way of examples.
（実施例） 第１表に供試材の化学成分およびSSRT（Slow Strain Ra
te Technique）試験によるSCC試験結果および曲げ試験
結果を示す。供試合金は真空溶解後、熱間圧延を施し65
0℃で焼鈍を実施して得たものであった。(Example) Table 1 shows the chemical composition of the test material and SSRT (Slow Strain Ra).
te Technique) SCC test results and bending test results are shown. The match money is vacuum melted and then hot-rolled.
It was obtained by carrying out annealing at 0 ° C.
SSRT試験は、平行部直径3mm×長さ20mmの引張試験片を
用い、沸騰硝酸中で2.17×10-6S-1の歪み速度で引張る
ことにより実施した。硝酸濃度は共沸濃度69.8％（以
下、70％と表示）を境に、低濃度側と高濃度側の両濃度
を採用した。SCCの判定は破断歪量と破面観察とで行
い、同じ温度のシリコンオイル中で同じ引張り試験を実
施した場合の破断歪と比較し、歪量が減少するととも
に、破面がSCC特有の粒内へき開状になっているものをS
CCと発生した。The SSRT test was carried out by using a tensile test piece having a parallel part diameter of 3 mm and a length of 20 mm, and pulling it in boiling nitric acid at a strain rate of 2.17 × 10 −6 S −1 . The nitric acid concentration was set at both the low concentration side and the high concentration side, with an azeotropic concentration of 69.8% (hereinafter referred to as 70%) as the boundary. SCC judgment is performed by rupture strain amount and fracture surface observation, and compared with the rupture strain when the same tensile test is performed in silicon oil at the same temperature, the strain amount decreases and the fracture surface has SCC-specific grains. S that has an incision
It occurred with CC.
結果を同じく第１表に示す。The results are also shown in Table 1.
第１表に示された結果から、共沸濃度およびそれ以下の
70％HNO3と50％HNO3中では、純ZrでもSCCは発生しない
が共沸濃度以上の80％、98％HNO3中ではSCCを発生す
る。Ti量1.2％でもSCCは発生する。5.5％のTiを添加す
ると80％HNO3ではSCCを発生しなくなるが、98％では発
生するので、共沸濃度以上の硝酸中のSCCを防止するに
は5.0％以上のTi添加が有効であるが、望ましくは10％
以上添加する必要がある。 From the results shown in Table 1, the azeotropic concentration and below
In 70% HNO 3 and 50% HNO 3 , SCC does not occur even with pure Zr, but SCC occurs in 80% and 98% HNO 3 above the azeotropic concentration. SCC occurs even with a Ti content of 1.2%. When 5.5% Ti is added, SCC does not occur in 80% HNO 3 , but it occurs in 98%, so it is effective to add 5.0% or more Ti to prevent SCC in nitric acid above the azeotropic concentration. But preferably 10%
It is necessary to add above.
構造用材として使用するには、優れた加工性を有してい
ることが必要であるので、曲げ試験を実施した。曲げ試
験は、板厚2mmの板材を半径4mmで曲げることにより行っ
た。合金ＥのようにTi含有量が28％では割れないが、37
％では割れが発生した。合金Ｈ参照。また、Fe、Cr、
Ｈ、Ｎ、Ｏの不純物含有量が増加すると曲げ性能が劣化
し、割れを発生する。合金Ｉ〜Ｌ参照。In order to use it as a structural material, it is necessary to have excellent workability, so a bending test was conducted. The bending test was performed by bending a plate material having a plate thickness of 2 mm with a radius of 4 mm. Like the alloy E, when the Ti content is 28%, it does not crack, but 37
%, Cracking occurred. See alloy H. In addition, Fe, Cr,
When the H, N, and O impurity contents increase, the bending performance deteriorates and cracks occur. See Alloys I-L.
（発明の効果） 本発明は、以上説明したように構成されているので、従
来、共沸濃度以上の硝酸に対し高耐食性を有する材料が
なかったけれども、Zrに適切なTiを加え、不純物元素を
制限することによって耐応力腐食割れ性を改善でき、こ
れにより共沸濃度以上の硝酸に対して耐食性の優れた合
金が得られたという顕著な効果が奏される。(Effect of the invention) Since the present invention is configured as described above, conventionally, although there was no material having a high corrosion resistance to nitric acid having an azeotropic concentration or higher, appropriate Ti was added to Zr as an impurity element. The stress corrosion cracking resistance can be improved by limiting the above, and this has a remarkable effect that an alloy excellent in corrosion resistance to nitric acid having an azeotropic concentration or more is obtained.
Claims (1)
N:0.03％以下、 H:0.01％以下にそれぞれ制限する、 より成る合金組成を有し、耐応力腐食割れ性に優れた、
共沸濃度を超えた70％超の濃度の硝酸溶液を取り扱うプ
ラント用構造材。1. Ti: 5.0 to 30% by weight, oxygen: 0.2% or less, balance Zr and unavoidable impurities However, as impurities, Fe: 0.3% or less, Cr: 0.1% or less,
N: 0.03% or less, H: 0.01% or less, respectively.
A structural material for plants that handles nitric acid solutions with concentrations exceeding 70%, which exceeds the azeotropic concentration.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1114789A JPH0674470B2 (en) | 1989-05-08 | 1989-05-08 | Structural material for nitric acid plant |
| DE68916235T DE68916235T2 (en) | 1989-05-08 | 1989-12-06 | Zirconium-based alloy with increased resistance to corrosion by nitric acid and with good creep resistance. |
| EP89122542A EP0396821B1 (en) | 1989-05-08 | 1989-12-06 | Zirconium alloy having improved corrosion resistance in nitric acid and good creep strength |
| US07/447,843 US5026521A (en) | 1989-05-08 | 1989-12-08 | Zirconium-titanium and/or tantalum oxygen alloy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1114789A JPH0674470B2 (en) | 1989-05-08 | 1989-05-08 | Structural material for nitric acid plant |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02294446A JPH02294446A (en) | 1990-12-05 |
| JPH0674470B2 true JPH0674470B2 (en) | 1994-09-21 |
Family
ID=14646723
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1114789A Expired - Fee Related JPH0674470B2 (en) | 1989-05-08 | 1989-05-08 | Structural material for nitric acid plant |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0674470B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112281026B (en) * | 2020-10-28 | 2022-03-29 | 西部新锆核材料科技有限公司 | Preparation method and application of corrosion-resistant zirconium alloy and cast ingot thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62222037A (en) * | 1986-03-20 | 1987-09-30 | Power Reactor & Nuclear Fuel Dev Corp | Zirconium-base alloy excellent in resistance to oxidation by nitric acid |
-
1989
- 1989-05-08 JP JP1114789A patent/JPH0674470B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02294446A (en) | 1990-12-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |