JP2004091816A - Nickel-based alloy, heat treatment method for nickel-based alloy, and member for nuclear power with the use of nickel-based alloy - Google Patents

Nickel-based alloy, heat treatment method for nickel-based alloy, and member for nuclear power with the use of nickel-based alloy Download PDF

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JP2004091816A
JP2004091816A JP2002251645A JP2002251645A JP2004091816A JP 2004091816 A JP2004091816 A JP 2004091816A JP 2002251645 A JP2002251645 A JP 2002251645A JP 2002251645 A JP2002251645 A JP 2002251645A JP 2004091816 A JP2004091816 A JP 2004091816A
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nickel
based alloy
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heat treatment
temperature
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JP3794999B2 (en
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Toshihiko Iwamura
岩村 俊彦
Yasunao Yamaguchi
山口 康直
Juntaro Shimizu
清水 純太郎
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Mitsubishi Heavy Industries Ltd
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Mitsubishi Heavy Industries Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a nickel-based alloy having a superior grain-boundary type stress-corrosion cracking resistance in water of a high temperature and a high pressure, and endurance for a long service in the water of the high temperature and the high pressure in the vessel of a nuclear reactor. <P>SOLUTION: The nickel-based alloy has a chemical composition comprising, by weight percentage, 0.08% or less C, 0.35% or less Si, 0.35% or less Mn, 0.015% or less P, 0.015% or less S, 50% to 55% Ni, 17% to 21% Cr, 2.8% to 3.3% Mo, 0.3% or less Cu, 0.2% to 0.8% Al, 0.65% to 1.15% Ti, 4.75% to 5.50% Nb+Ta, 0.006% or less B, and the balance Fe with unavoidable impurities. The heat treatment method is characterized by solution-treating the nickel-based alloy having the above chemical composition at a temperature of 995°C to 1,040°C, for 30 minutes to 20 hours. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
本発明は、例えば原子炉炉内環境のように、高温高圧水中で優れた耐応力腐食割れ性を有するニッケル基合金、およびその熱処理方法に関する。更に、このようなニッケル基合金を、各種の押さえ部品、ばね、ピン、ボルトなどの高強度部材として用いることによって、高温高圧水中で長時間使用された場合であっても耐応力腐食割れ性に優れた原子力用部材に関する。
【0002】
【従来の技術】
析出強化型ニッケル基合金のNCF718合金は、高強度で耐食性が優れていることから、原子炉炉内構造物のスプリング、ベローズ、燃料支持格子、ボルトなどの原子力用部材に使用されている。
【0003】
【発明が解決しようとする課題】
しかしながら、析出強化型ニッケル基合金のNCF718合金は、高温高圧水中において、高引張応力が作用すると、粒界型応力腐食割れを生じることがあるということが知られている。
【0004】
原子炉の炉内環境は、高温高圧水中であることから、NCF718合金からなる原子力用部材は、高引張応力が作用すると、粒界型応力腐食割れを生じる可能性があるという問題がある。
【0005】
本発明はこのような事情に鑑みてなされたものであり、NCF718合金よりさらに高温高圧水中で優れた耐粒界型応力腐食割れ性を有し、もって、高温高圧水中の環境下で長時間の使用に耐えることが可能なニッケル基合金、ニッケル基合金の熱処理方法、およびニッケル基合金を用いた原子力用部材を提供することを目的とする。
【0006】
【課題を解決するための手段】
上記の目的を達成するために、本発明では、以下のような手段を講じる。
【0007】
すなわち、請求項1の発明のニッケル基合金の熱処理方法は、重量パーセントでC:0.08%以下、Si:0.35%以下、Mn:0.35%以下、P:0.015%以下、S:0.015%以下、Ni:50%以上55%以下、Cr:17%以上21%以下、Mo:2.8%以上3.3%以下、Cu:0.3%以下、Al:0.2%以上0.8%以下、Ti:0.65%以上1.15%以下、Nb+Ta:4.75%以上5.50%以下、B:0.006%以下、および残部Feならびに不可避的不純物からなる化学組成を有するニッケル基合金を、995℃〜1040℃の温度で、30分〜20時間加熱して固溶化熱処理する。
【0008】
請求項2の発明のニッケル基合金は、請求項1の発明のニッケル基合金の熱処理方法を実施し、かつCrの重量パーセントを19%以上21%以下としている。
【0009】
請求項3の発明のニッケル基合金は、請求項1の発明のニッケル基合金の熱処理方法を実施し、かつNbの重量パーセントを4.9%以上5.4%以下としている。
【0010】
請求項4の発明のニッケル基合金は、請求項1の発明のニッケル基合金の熱処理方法を実施し、かつCrの重量パーセントを19%以上21%以下、Nbの重量パーセントを4.9%以上5.4%以下としている。
【0011】
請求項5の発明の、ニッケル基合金を用いた原子力用部材は、請求項2乃至4のうち少なくとも何れか1項の発明のニッケル基合金を用いて製造したものである。
【0012】
従って、請求項1から請求項4の発明においては、以上のような手段を講じることにより、高温高圧水中で優れた耐粒界型応力腐食割れ性を有し、例えば原子炉炉内のような高温高圧水中の環境下で長時間の使用に耐えることが可能なニッケル基合金を実現することができる。
【0013】
また、請求項5の発明では、請求項2から請求項4のようなニッケル基合金を用いて製造した原子力用部材を燃料集合体や炉内構造物に適用することによって、高温高圧水中であっても、優れた耐粒界型応力腐食割れ性を有し、例えば原子炉炉内のような高温高圧水中の環境下であっても長時間の使用に耐えることが可能な原子力用部材を実現することができる。
【0014】
【発明の実施の形態】
以下に、本発明の実施の形態について図面を参照しながら説明する。
【0015】
本発明の実施の形態を図1から図11、および表1から表2を用いて説明する。
【0016】
【表1】

Figure 2004091816
【0017】
本発明の実施の形態では、表1に化学成分(重量%)を示す試験組成1〜試験組成6の試作鍛造材を対象として、950℃から1070℃の温度で3時間保持した後空冷する固溶化熱処理を施した後、760℃の温度で5時間保持した後炉内冷却によって760℃から650℃まで降温し、更に650℃の温度で1時間保持した後空冷する時効処理を施した。
【0018】
その後、1)低歪速度引張試験、2)粒界腐食試験、3)引張試験、4)結晶粒度測定を行った。なお、試験組成1はJIS規格に適合する標準材(NCF718合金)、試験組成2は試験組成1よりもNb量が少ない低Nb材、試験組成3はNb量が試験組成2よりも多く試験組成4よりも少ない中Nb材、試験組成4は試験組成3よりもNb量が多い高Nb材、試験組成5は試験組成1よりもCr量が少ない低Cr材、試験組成6は試験組成1よりもCr量が多い高Cr材である。
【0019】
1)低歪速度引張試験
図1(a)に正面図を、図1(b)に側面図を示すようなノッチ付きの試験片12を用いて、軽水炉模擬環境下の高温高圧純水中(360℃、≦214kg/cmG)で低歪速度引張試験(引張速度:0.1μm/min)を行った。その結果、図2および図3に示すように試験片12の粒界破面率は、固溶化熱処理温度が高くなると減少するという傾向が認められた。また、固溶化熱処理温度が1025℃以上では、試験組成4(高Nb材)と試験組成5(低Cr材)とを除く何れの材料とも粒界破面率がほぼゼロとなった。一方、粒界破面率は、Nb量が増加するほど、またCr量が減少するほど増大する傾向が認められた。
【0020】
図1に示すようなノッチ付きの試験片12を用いた低歪速度引張試験は、応力腐食割れ(以下、「SCC」と称する。)に対する感受性を評価するための過酷な試験方法である。そこで、低歪速度引張試験でのSCC感受性のしきい値を粒界破面率で10%以下と仮定すると、固溶化熱処理温度は995℃以上で、Cr量は重量割合で19%以上21%以下が、Nb量は重量割合で5.4%以下が望ましいことがわかる。
【0021】
2)粒界腐食(コリオ)試験
粒界腐食(コリオ)試験(5Kmol/mHNO+0.077Kmol/mCr 2−溶液中で3時間の沸騰試験)を行った結果、得られた固溶化熱処理温度と腐食速度との関係を図4および図5に示す。図4および図5に示すように、腐食速度は、試験組成4(高Nb材)が、固溶化熱処理温度に関わらず他の試験組成の場合に比べて大きな値を示すことが認められた。その他の試験組成の腐食速度は、固溶化熱処理温度980℃の場合が大きく、固溶化熱処理温度が995℃から1025℃では980℃に比べて小さな値を示している。したがって、耐粒界腐食性の観点からは、固溶化熱処理温度は995℃以上で、Nb量は重量割合で5.4%以下が望ましいことがわかる。
【0022】
3)引張試験
引張試験の結果を、固溶化熱処理温度と0.2%耐力との関係にまとめたグラフを図6および図7に、固溶化熱処理温度と引張強さとの関係にまとめたグラフを図8および図9にそれぞれ示す。
【0023】
図6および図7に示すように、0.2%耐力は、固溶化熱処理温度が高くなると若干低下する傾向が認められるものの、図7に示すように、Cr量の変化に対してはほぼ同等で有意差が認められないが、図6に示すように、試験組成2(低Nb材)では試験組成1(標準材)よりも低強度で、JIS規格を下回っている。また、図8および図9に示すように、引張強さは、固溶化熱処理温度が高くなると若干低下する傾向が認められるものの、図9に示すように、Cr量の変化に対してはほぼ同等で有意差が認められないが、図8に示すように、試験組成2(低Nb材)では試験組成1(標準材)よりも低強度で、JIS規格を下回っている。したがって、引張試験の結果からは、固溶化熱処理温度は980℃以上で、Nb量は重量割合で4.9%以上が望ましいことがわかる。
【0024】
4)結晶粒度測定
結晶粒度測定の結果を、固溶化熱処理温度と結晶粒度番号との関係にまとめたグラフを図10および図11にそれぞれ示す。結晶粒度番号は、何れの試験組成に対しても、固溶化熱処理温度が高くなると共に小さくなる傾向を示している。固溶化熱処理温度が1070℃以上では、いずれの試験組成も結晶粒度番号が5以下となっている。結晶粒度番号が小さいことは望ましくないため、固溶化熱処理温度としては1040℃以下が望ましいことがわかる。
【0025】
5)固溶化熱処理
以上のことから、固溶化熱処理温度としては、995℃〜1040℃が望ましいことがわかる。一方、固溶化熱処理時間は、ここでは一例として3時間としている。
【0026】
そこで、固溶化熱処理温度が995℃〜1040℃の場合の固溶化熱処理時間を以下に示すようなラルソン・ミラーのパラメータPを用いて検討した。
【0027】
P=T(c+Logt)
ただし、P:パラメータ、T:絶対温度(K)、c=定数(ここでは23)、t:時間(hr)である。ここで行なった固溶化熱処理条件および加熱時間を変化させた場合について下式のラルソン・ミラーのパラメータで整理した結果を表2に示す。
【0028】
【表2】
Figure 2004091816
【0029】
表2に示すように、1040℃の温度で3時間加熱した場合のパラメータは30825で、995℃の温度で3時間加熱した場合のパラメータは29769である。995℃の温度で20時間加熱した場合のパラメータは30814で、1040℃の温度で3時間加熱した場合のパラメータ(30825)とほぼ同等である。一方、1040℃の温度で30分間加熱した場合のパラメータは29804で、995℃の温度で3時間加熱した場合のパラメータ(29769)とほぼ同等である。
【0030】
したがって、固溶化熱処理時間としては、30分〜20時間が望ましいことがわかる。
【0031】
以上のことから、耐粒界型応力腐食割れ性に優れた析出強化型のニッケル基合金としては、Crの重量パーセントが19%以上21%以下、Nbの重量パーセントが4.9%以上5.4%以下であり、その他はNCF718合金と同等の化学組成を有するものがよい。
【0032】
また、このようなニッケル基合金の熱処理方法としては、995℃〜1040℃の温度で、30分〜20時間加熱する固溶化熱処理をすればよい。
【0033】
したがって、このようなニッケル基合金によって製造されたスプリング、ベローズ、燃料支持格子、ボルトなどの原子力用部材を、燃料集合体や原子炉炉内構造物に用いることによって、高温高圧水中であっても、優れた耐粒界型応力腐食割れ性を有し、原子炉炉内の高温高圧水中の環境下で長時間の使用に耐えることが可能となる。
【0034】
以上、本発明の好適な実施の形態について、添付図面を参照しながら説明したが、本発明はかかる構成に限定されない。特許請求の範囲の発明された技術的思想の範疇において、当業者であれば、各種の変更例及び修正例に想到し得るものであり、それら変更例及び修正例についても本発明の技術的範囲に属するものと了解される。
【0035】
【発明の効果】
以上説明したように、本発明によれば、NCF718合金よりもさらに高温高圧水中で優れた耐粒界型応力腐食割れ性を有し、もって、高温高圧水中の環境下で長時間の使用に耐えることが可能なニッケル基合金、ニッケル基合金の熱処理方法、およびニッケル基合金を用いた原子力用部材を実現することができる。
【図面の簡単な説明】
【図1】試験片の形状を示す正面図および側面図
【図2】固溶化熱処理温度と粒界破面率との関係を示す図(Nb量に対する傾向)
【図3】固溶化熱処理温度と粒界破面率との関係を示す図(Cr量に対する傾向)
【図4】固溶化熱処理温度と腐食速度との関係を示す図(Nb量に対する傾向)
【図5】固溶化熱処理温度と腐食速度との関係を示す図(Cr量に対する傾向)
【図6】固溶化熱処理温度と0.2%耐力との関係を示す図(Nb量に対する傾向)
【図7】固溶化熱処理温度と0.2%耐力との関係を示す図(Cr量に対する傾向)
【図8】固溶化熱処理温度と引張強さとの関係を示す図(Nb量に対する傾向)
【図9】固溶化熱処理温度と引張強さとの関係を示す図(Cr量に対する傾向)
【図10】固溶化熱処理温度と結晶粒度番号との関係を示す図(Nb量に対する傾向)
【図11】固溶化熱処理温度と結晶粒度番号との関係を示す図(Cr量に対する傾向)
【符号の説明】
12…試験片[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nickel-based alloy having excellent stress corrosion cracking resistance in high-temperature and high-pressure water, such as in a reactor environment, and a heat treatment method thereof. Furthermore, by using such a nickel-based alloy as a high-strength member such as various holding parts, springs, pins, and bolts, even when used in high-temperature and high-pressure water for a long time, it is resistant to stress corrosion cracking. Regarding excellent nuclear components.
[0002]
[Prior art]
NCF718 alloy, a precipitation-strengthened nickel-base alloy, is used for nuclear members such as springs, bellows, fuel support grids, and bolts of reactor internals because of its high strength and excellent corrosion resistance.
[0003]
[Problems to be solved by the invention]
However, it is known that the NCF718 alloy of the precipitation-strengthened nickel-base alloy may cause grain boundary stress corrosion cracking when high tensile stress acts in high-temperature and high-pressure water.
[0004]
Since the environment inside the nuclear reactor is in high-temperature and high-pressure water, there is a problem that a nuclear member made of NCF718 alloy may cause grain boundary stress corrosion cracking when high tensile stress is applied.
[0005]
The present invention has been made in view of such circumstances, and has more excellent grain boundary stress corrosion cracking resistance in high-temperature and high-pressure water than the NCF718 alloy. It is an object of the present invention to provide a nickel-based alloy that can withstand use, a heat treatment method for the nickel-based alloy, and a nuclear power member using the nickel-based alloy.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention takes the following measures.
[0007]
That is, in the heat treatment method for a nickel-based alloy according to the first aspect of the present invention, C: 0.08% or less, Si: 0.35% or less, Mn: 0.35% or less, P: 0.015% or less by weight. , S: 0.015% or less, Ni: 50% to 55%, Cr: 17% to 21%, Mo: 2.8% to 3.3%, Cu: 0.3% or less, Al: 0.2% or more and 0.8% or less, Ti: 0.65% or more and 1.15% or less, Nb + Ta: 4.75% or more and 5.50% or less, B: 0.006% or less, and the balance Fe and unavoidable A nickel-based alloy having a chemical composition of a chemical impurity is heated at a temperature of 995 ° C. to 1040 ° C. for 30 minutes to 20 hours to perform a solution heat treatment.
[0008]
According to a second aspect of the present invention, there is provided a nickel-base alloy according to the first aspect of the present invention, wherein the heat treatment method for the nickel-base alloy is performed, and the weight percentage of Cr is set to be 19% or more and 21% or less.
[0009]
According to a third aspect of the present invention, there is provided a nickel-base alloy according to the first aspect of the present invention, wherein the weight percent of Nb is 4.9% or more and 5.4% or less.
[0010]
A nickel-base alloy according to a fourth aspect of the present invention is a method for heat-treating a nickel-base alloy according to the first aspect of the present invention, wherein the weight percent of Cr is 19% or more and 21% or less and the weight percent of Nb is 4.9% or more. 5.4% or less.
[0011]
A nuclear power member using a nickel-based alloy according to a fifth aspect of the invention is manufactured using the nickel-based alloy according to at least one of the second to fourth aspects.
[0012]
Therefore, in the inventions of claims 1 to 4, by taking the above measures, it has excellent grain boundary type stress corrosion cracking resistance in high-temperature and high-pressure water. A nickel-based alloy that can withstand long-term use in an environment of high-temperature and high-pressure water can be realized.
[0013]
Further, in the invention of claim 5, by applying the nuclear member manufactured by using the nickel-based alloy as in claims 2 to 4 to a fuel assembly or a furnace internal structure, it can be used in high-temperature and high-pressure water. Achieved a nuclear component that has excellent grain boundary stress corrosion cracking resistance and can withstand long-term use even in high-temperature, high-pressure water environments such as in nuclear reactors. can do.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
An embodiment of the present invention will be described with reference to FIGS. 1 to 11 and Tables 1 and 2.
[0016]
[Table 1]
Figure 2004091816
[0017]
In the embodiment of the present invention, for the test forged materials of Test Composition 1 to Test Composition 6 whose chemical components (% by weight) are shown in Table 1, the temperature is maintained at a temperature of 950 ° C. to 1070 ° C. for 3 hours and then air-cooled. After the solution heat treatment, the steel was kept at a temperature of 760 ° C. for 5 hours, cooled down from 760 ° C. to 650 ° C. by cooling in a furnace, further kept at a temperature of 650 ° C. for 1 hour, and then subjected to an aging treatment of air cooling.
[0018]
Thereafter, 1) low strain rate tensile test, 2) intergranular corrosion test, 3) tensile test, and 4) crystal grain size measurement were performed. Test composition 1 is a standard material (NCF718 alloy) conforming to the JIS standard, test composition 2 is a low Nb material having a smaller Nb content than test composition 1, and test composition 3 is a test composition having a larger Nb content than test composition 2. Medium Nb material less than 4, test composition 4 is a high Nb material having more Nb content than test composition 3, test composition 5 is a low Cr material having less Cr content than test composition 1, and test composition 6 is more than test composition 1. Is also a high Cr material having a large amount of Cr.
[0019]
1) Low strain rate tensile test Using a notched test piece 12 as shown in a front view in FIG. 1A and a side view in FIG. A low strain rate tensile test (tensile speed: 0.1 μm / min) was performed at 360 ° C. and ≦ 214 kg / cm 2 G). As a result, as shown in FIG. 2 and FIG. 3, a tendency was observed that the grain boundary fracture surface ratio of the test piece 12 decreased as the solution heat treatment temperature increased. When the solution heat treatment temperature was 1025 ° C. or higher, the grain boundary fracture rate was almost zero for all materials except Test Composition 4 (high Nb material) and Test Composition 5 (low Cr material). On the other hand, the grain boundary fracture surface tended to increase as the Nb amount increased and as the Cr amount decreased.
[0020]
The low strain rate tensile test using the notched test piece 12 as shown in FIG. 1 is a severe test method for evaluating susceptibility to stress corrosion cracking (hereinafter, referred to as “SCC”). Therefore, assuming that the threshold value of the SCC sensitivity in the low strain rate tensile test is 10% or less in terms of the grain boundary fracture ratio, the solution heat treatment temperature is 995 ° C. or more, and the Cr content is 19% or more and 21% by weight. The following shows that the Nb content is desirably 5.4% or less by weight.
[0021]
2) Intergranular corrosion (corio) test Intergranular corrosion (corio) test (5 Kmol / m 3 HNO 3 +0.077 Kmol / m 3 Cr 2 O 7 2- boil test in 3-hour solution) was obtained. The relationship between the solution heat treatment temperature and the corrosion rate is shown in FIGS. As shown in FIGS. 4 and 5, it was confirmed that the corrosion rate of Test Composition 4 (high Nb material) showed a larger value than that of other test compositions regardless of the solution heat treatment temperature. The corrosion rates of the other test compositions are large at the solution heat treatment temperature of 980 ° C., and are smaller than those at 980 ° C. when the solution heat treatment temperature is 995 ° C. to 1025 ° C. Therefore, from the viewpoint of the intergranular corrosion resistance, it is understood that the solution heat treatment temperature is preferably 995 ° C. or more and the Nb content is preferably 5.4% or less by weight.
[0022]
3) Tensile test FIGS. 6 and 7 are graphs summarizing the results of the tensile test in the relationship between solution heat treatment temperature and 0.2% proof stress, and graphs summarizing the relationship between solution heat treatment temperature and tensile strength. These are shown in FIGS. 8 and 9, respectively.
[0023]
As shown in FIGS. 6 and 7, the 0.2% proof stress tends to decrease slightly as the solution heat treatment temperature increases, but as shown in FIG. However, as shown in FIG. 6, the test composition 2 (low Nb material) has lower strength than the test composition 1 (standard material) and is lower than the JIS standard, as shown in FIG. Further, as shown in FIGS. 8 and 9, the tensile strength tends to slightly decrease as the solution heat treatment temperature increases, but as shown in FIG. 9, the tensile strength is almost equal to the change in the Cr content. Although no significant difference was observed in the test composition, as shown in FIG. 8, the test composition 2 (low Nb material) had lower strength than the test composition 1 (standard material) and was lower than the JIS standard. Therefore, the results of the tensile test show that the solution heat treatment temperature is desirably 980 ° C. or higher and the Nb content is desirably 4.9% or more by weight.
[0024]
4) Measurement of crystal grain size FIGS. 10 and 11 show graphs in which the results of the crystal grain size measurement are summarized in the relationship between the solution heat treatment temperature and the crystal grain size number. The grain size numbers tend to decrease with increasing solution heat treatment temperature for any of the test compositions. When the solution heat treatment temperature is 1070 ° C. or higher, the crystal grain size number is 5 or less in any of the test compositions. Since it is not desirable that the crystal grain number is small, it is understood that the solution heat treatment temperature is desirably 1040 ° C. or less.
[0025]
5) Solution heat treatment From the above, it can be seen that the solution heat treatment temperature is preferably 995 ° C to 1040 ° C. On the other hand, the solution heat treatment time is, for example, 3 hours here.
[0026]
Therefore, the solution heat treatment time when the solution heat treatment temperature was 995 ° C. to 1040 ° C. was examined using Larson-Miller parameter P as shown below.
[0027]
P = T (c + Logt)
Here, P: parameter, T: absolute temperature (K), c = constant (here, 23), and t: time (hr). Table 2 shows the results obtained by rearranging the solution heat treatment conditions and the heating time performed here using the following Larson-Miller parameters.
[0028]
[Table 2]
Figure 2004091816
[0029]
As shown in Table 2, the parameter when heating at a temperature of 1040 ° C. for 3 hours is 30825, and the parameter when heating at a temperature of 995 ° C. for 3 hours is 29969. The parameter when heating at a temperature of 995 ° C. for 20 hours is 30814, which is almost the same as the parameter (30825) when heating at a temperature of 1040 ° C. for 3 hours. On the other hand, the parameter when heated at a temperature of 1040 ° C. for 30 minutes is 29804, which is almost the same as the parameter (29769) when heated at a temperature of 995 ° C. for 3 hours.
[0030]
Therefore, it is understood that the solution heat treatment time is desirably 30 minutes to 20 hours.
[0031]
From the above, as a precipitation-strengthened nickel-base alloy having excellent grain boundary stress corrosion cracking resistance, the weight percent of Cr is 19% or more and 21% or less, and the weight percent of Nb is 4.9% or more and 5. It is preferably 4% or less, and the others have the same chemical composition as the NCF718 alloy.
[0032]
As a heat treatment method for such a nickel-based alloy, a solution heat treatment at a temperature of 995 ° C. to 1040 ° C. for 30 minutes to 20 hours may be performed.
[0033]
Therefore, by using nuclear members such as springs, bellows, fuel support grids, and bolts made of such nickel-based alloys for fuel assemblies and reactor internal structures, even in high-temperature and high-pressure water. It has excellent grain boundary stress corrosion cracking resistance and can withstand long-term use under high-temperature and high-pressure water environment in a nuclear reactor.
[0034]
Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to such configurations. Within the scope of the invented technical concept of the claims, those skilled in the art will be able to conceive various changes and modifications, and those changes and modifications will be described in the technical scope of the present invention. It is understood that it belongs to.
[0035]
【The invention's effect】
As described above, according to the present invention, it has more excellent intergranular stress corrosion cracking resistance in high-temperature and high-pressure water than NCF718 alloy, and can withstand long-term use in an environment of high-temperature and high-pressure water. A nickel-based alloy, a heat treatment method for a nickel-based alloy, and a nuclear member using the nickel-based alloy can be realized.
[Brief description of the drawings]
FIG. 1 is a front view and a side view showing a shape of a test piece; FIG. 2 is a view showing a relationship between a solution heat treatment temperature and a grain boundary fracture ratio (a tendency with respect to an Nb content).
FIG. 3 is a graph showing the relationship between the solution heat treatment temperature and the grain boundary fracture surface ratio (trend to Cr content).
FIG. 4 is a graph showing a relationship between a solution heat treatment temperature and a corrosion rate (a tendency with respect to an Nb amount).
FIG. 5 is a graph showing the relationship between the solution heat treatment temperature and the corrosion rate (trend to Cr content).
FIG. 6 is a graph showing the relationship between the solution heat treatment temperature and 0.2% proof stress (trend to Nb amount).
FIG. 7 is a graph showing the relationship between the solution heat treatment temperature and 0.2% proof stress (trend to Cr content).
FIG. 8 is a graph showing a relationship between a solution heat treatment temperature and a tensile strength (a tendency with respect to an Nb amount).
FIG. 9 is a graph showing the relationship between the solution heat treatment temperature and the tensile strength (trend to Cr content).
FIG. 10 is a graph showing a relationship between a solution heat treatment temperature and a crystal grain size number (a tendency with respect to an Nb amount).
FIG. 11 is a graph showing the relationship between the solution heat treatment temperature and the crystal grain size number (trend to Cr content).
[Explanation of symbols]
12 ... Test piece

Claims (5)

重量パーセントでC:0.08%以下、Si:0.35%以下、Mn:0.35%以下、P:0.015%以下、S:0.015%以下、Ni:50%以上55%以下、Cr:17%以上21%以下、Mo:2.8%以上3.3%以下、Cu:0.3%以下、Al:0.2%以上0.8%以下、Ti:0.65%以上1.15%以下、Nb+Ta:4.75%以上5.50%以下、B:0.006%以下、および残部Feならびに不可避的不純物からなる化学組成を有するニッケル基合金を、995℃〜1040℃の温度で、30分〜20時間加熱して固溶化熱処理するようにしたニッケル基合金の熱処理方法。C: 0.08% or less, Si: 0.35% or less, Mn: 0.35% or less, P: 0.015% or less, S: 0.015% or less, Ni: 50% or more and 55% by weight percent Hereinafter, Cr: 17% to 21%, Mo: 2.8% to 3.3%, Cu: 0.3%, Al: 0.2% to 0.8%, Ti: 0.65 % To 1.15%, Nb + Ta: 4.75% to 5.50%, B: 0.006% or less, and a nickel-based alloy having a chemical composition comprising Fe and unavoidable impurities at 995 ° C. A heat treatment method for a nickel-based alloy in which a solution treatment is performed by heating at a temperature of 1040 ° C. for 30 minutes to 20 hours. 請求項1に記載のニッケル基合金の熱処理方法を実施し、かつCrの重量パーセントを19%以上21%以下としたニッケル基合金。A nickel-based alloy, wherein the method for heat-treating a nickel-based alloy according to claim 1 is performed, and the weight percent of Cr is 19% or more and 21% or less. 請求項1に記載のニッケル基合金の熱処理方法を実施し、かつNbの重量パーセントを4.9%以上5.4%以下としたニッケル基合金。A nickel-based alloy, wherein the method for heat-treating a nickel-based alloy according to claim 1 is performed, and the weight percentage of Nb is 4.9% or more and 5.4% or less. 請求項1に記載のニッケル基合金の熱処理方法を実施し、かつCrの重量パーセントを19%以上21%以下、Nbの重量パーセントを4.9%以上5.4%以下としたニッケル基合金。A nickel-based alloy, wherein the nickel-based alloy heat treatment method according to claim 1 is performed, and the weight percent of Cr is 19% or more and 21% or less, and the weight percent of Nb is 4.9% or more and 5.4% or less. 請求項2乃至4のうち少なくとも何れか1項に記載のニッケル基合金を用いて製造した原子力用部材。A nuclear power member manufactured using the nickel-based alloy according to at least one of claims 2 to 4.
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010071017A1 (en) 2008-12-15 2010-06-24 株式会社東芝 Jet pump beam and manufacturing method therefor
CN102776415A (en) * 2012-08-17 2012-11-14 北京科技大学 Method for preparing high-tensile-ductility Ni (Bi) alloy
CN102776455A (en) * 2012-08-17 2012-11-14 北京科技大学 Method for preparing high-stretching plasticity Ni (Bi) alloy by using isothermal heat treatment
JP2014224310A (en) * 2013-04-19 2014-12-04 日立金属株式会社 Fe-Ni-BASED SUPERALLOY AND METHOD FOR PRODUCING THE SAME

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010071017A1 (en) 2008-12-15 2010-06-24 株式会社東芝 Jet pump beam and manufacturing method therefor
CN102776415A (en) * 2012-08-17 2012-11-14 北京科技大学 Method for preparing high-tensile-ductility Ni (Bi) alloy
CN102776455A (en) * 2012-08-17 2012-11-14 北京科技大学 Method for preparing high-stretching plasticity Ni (Bi) alloy by using isothermal heat treatment
JP2014224310A (en) * 2013-04-19 2014-12-04 日立金属株式会社 Fe-Ni-BASED SUPERALLOY AND METHOD FOR PRODUCING THE SAME

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