JP3462182B2 - Method for producing chromium-containing oxide dispersion strengthened ferritic iron alloy tube - Google Patents
Method for producing chromium-containing oxide dispersion strengthened ferritic iron alloy tubeInfo
- Publication number
- JP3462182B2 JP3462182B2 JP2001062913A JP2001062913A JP3462182B2 JP 3462182 B2 JP3462182 B2 JP 3462182B2 JP 2001062913 A JP2001062913 A JP 2001062913A JP 2001062913 A JP2001062913 A JP 2001062913A JP 3462182 B2 JP3462182 B2 JP 3462182B2
- Authority
- JP
- Japan
- Prior art keywords
- annealing
- rolling
- tube
- strength
- iron alloy
- 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
- 229910000640 Fe alloy Inorganic materials 0.000 title claims description 25
- 238000004519 manufacturing process Methods 0.000 title claims description 20
- 239000011651 chromium Substances 0.000 title claims description 17
- 229910001175 oxide dispersion-strengthened alloy Inorganic materials 0.000 title claims description 9
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims description 8
- 229910052804 chromium Inorganic materials 0.000 title claims description 8
- 238000000137 annealing Methods 0.000 claims description 93
- 238000005096 rolling process Methods 0.000 claims description 49
- 238000005097 cold rolling Methods 0.000 claims description 32
- 239000000843 powder Substances 0.000 claims description 20
- 238000000034 method Methods 0.000 claims description 15
- 239000006185 dispersion Substances 0.000 claims description 10
- 229910052751 metal Inorganic materials 0.000 claims description 9
- 239000002184 metal Substances 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 6
- 238000005245 sintering Methods 0.000 claims description 6
- 229910052719 titanium Inorganic materials 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 238000005728 strengthening Methods 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims 2
- 229910045601 alloy Inorganic materials 0.000 description 32
- 239000000956 alloy Substances 0.000 description 32
- 238000001953 recrystallisation Methods 0.000 description 20
- 239000013078 crystal Substances 0.000 description 12
- 230000000694 effects Effects 0.000 description 10
- 239000002245 particle Substances 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 8
- 238000011084 recovery Methods 0.000 description 8
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 7
- 238000005253 cladding Methods 0.000 description 7
- 239000010419 fine particle Substances 0.000 description 7
- 239000000446 fuel Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 6
- 230000008569 process Effects 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 3
- 239000002775 capsule Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 239000003758 nuclear fuel Substances 0.000 description 3
- 230000036961 partial effect Effects 0.000 description 3
- 230000002829 reductive effect Effects 0.000 description 3
- 238000005482 strain hardening Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 239000003779 heat-resistant material Substances 0.000 description 2
- 238000001192 hot extrusion Methods 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000005551 mechanical alloying Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 102200052313 rs9282831 Human genes 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910020068 MgAl Inorganic materials 0.000 description 1
- 102220479482 Puromycin-sensitive aminopeptidase-like protein_C21D_mutation Human genes 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
- G21C3/02—Fuel elements
- G21C3/04—Constructional details
- G21C3/06—Casings; Jackets
- G21C3/07—Casings; Jackets characterised by their material, e.g. alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/16—Both compacting and sintering in successive or repeated steps
- B22F3/162—Machining, working after consolidation
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0207—Using a mixture of prealloyed powders or a master alloy
- C22C33/0228—Using a mixture of prealloyed powders or a master alloy comprising other non-metallic compounds or more than 5% of graphite
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B21/00—Pilgrim-step tube-rolling, i.e. pilger mills
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/004—Heating the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
- B22F2003/248—Thermal after-treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Metallurgy (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Plasma & Fusion (AREA)
- High Energy & Nuclear Physics (AREA)
- General Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Heat Treatment Of Steel (AREA)
- Powder Metallurgy (AREA)
Description
【0001】[0001]
【発明が属する技術分野】本発明は、耐熱材料、とくに
高温で中性子照射の環境下で使用されるクロムを含む酸
化物分散強化型フェライト系鉄合金管の製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant material, and more particularly to a method for producing an oxide dispersion strengthened ferritic iron alloy tube containing chromium which is used under high temperature neutron irradiation environment.
【0002】[0002]
【従来の技術】発電用原子炉の高速増殖炉炉心構成部材
としては、従来オーステナイト系のステンレス鋼、例え
ばSUS316やその改良鋼が検討されてきた。しかしオース
テナイト系ステンレス鋼は高温強さはすぐれているが、
400〜700℃の高速中性子照射下における耐スエリング性
や耐クリープ性に限界があり、実用的高速増殖炉の炉心
構成用部材として必ずしも十分でない。これに対し、フ
ェライト系ステンレス鋼あるいはフェライト系高クロム
鉄合金は、オーステナイト系ステンレス鋼よりも高速中
性子照射劣化にたいする耐性はすぐれているが、高温ク
リープ強さないしは高温強さが劣っている。そこで、酸
化物の微細粒子をマトリクスに分散させて高温強さを向
上させた、酸化物分散強化型フェライト系高クロム鉄合
金の開発が進められ、とくに燃料の被覆管用としての適
用が検討されている。さらに、フェライト系ステンレス
鋼あるいはフェライト系鉄合金は、オーステナイト系ス
テンレス鋼よりも熱膨張係数は小さく熱伝導率が良好と
いう長所があり、高温強さが向上できれば、火力発電の
高温部材など耐熱用材料としての活用も期待できる。2. Description of the Related Art Conventionally, austenitic stainless steels such as SUS316 and its improved steels have been studied as a core constituent member of a fast breeder reactor of a nuclear reactor for power generation. However, austenitic stainless steel has excellent high temperature strength,
There is a limit to swelling resistance and creep resistance under fast neutron irradiation at 400 to 700 ℃, and it is not always sufficient as a core constituent member for practical fast breeder reactors. On the other hand, ferritic stainless steels or ferritic high chromium iron alloys have better resistance to fast neutron irradiation deterioration than austenitic stainless steels, but their high temperature creep strength or high temperature strength is inferior. Therefore, development of oxide-dispersion-strengthened ferritic high-chromium iron alloys in which fine particles of oxides are dispersed in a matrix to improve high-temperature strength is under way, and its application for fuel cladding is being studied. There is. Furthermore, ferritic stainless steel or ferritic iron alloy has the advantage that it has a smaller coefficient of thermal expansion and better thermal conductivity than austenitic stainless steel, and if high temperature strength can be improved, it can be used as a heat-resistant material such as high-temperature members for thermal power generation. Can also be expected to be utilized.
【0003】このようなフェライト系高クロム鉄合金と
して提案されているものに、質量%にてCrを11〜15%
程度含む、例えば(a)Fe−14%Cr−1%Ti−0.3
%Mo−0.25%Y2O3合金(MA957合金:米国特許第4
075010号)や(b)Fe−13%Cr−3%(Mo+W)
−0.5%Ti−0.1%C−0.35%Y2O3合金(英国特許
出願公開明細書GB2219004A号)などがある。これら
は、耐食性や耐酸化性のために不可欠なCrと高温強さ
確保のためのMoやWとを含有させた鉄合金に、Tiと
ともに酸化物としてY2O3を添加した合金である。T
iの添加は、Y 2O3と反応して酸化物粒子を極めて微
細にマトリクス中に分散させる作用がある。With such a ferritic high chromium iron alloy
In the amount of 11% to 15% of Cr in mass%
To some extent, for example (a) Fe-14% Cr-1% Ti-0.3
% Mo-0.25% YTwoOThreeAlloy (MA957 alloy: US Patent No. 4
075010) and (b) Fe-13% Cr-3% (Mo + W)
-0.5% Ti-0.1% C-0.35% YTwoOThreeAlloy (UK patent
Published application specification GB2219004A) and the like. these
Is the essential Cr and high temperature strength for corrosion resistance and oxidation resistance.
In order to secure the iron alloy containing Mo and W, Ti and
Y as oxideTwoOThreeIs an alloy to which is added. T
i is added to Y TwoOThreeReact with
It has the effect of finely dispersing it in the matrix.
【0004】酸化物を微細に分散させると、高温クリ−
プ強さないしは高温強さが大きく上昇するのは、変形に
伴う転位や粒界の移動を微細に分散した酸化物粒子が強
く拘束するためである。この微細分散粒子の効果は、一
般的に粒子の存在量が多いほど大きく、同じ含有量なら
その径が小さく、かつ均一に分散しているほど大であ
る。しかしながら、微細粒子の存在は、管などを成形す
る際の変形抵抗を増し、変形能を悪くして加工性を劣化
させるとともに、加工硬化した材料の焼鈍による軟化も
困難にさせる。When the oxide is finely dispersed, high temperature clear
The reason why the strength at high temperature or the high temperature strength greatly increases is because the finely dispersed oxide particles strongly restrain the dislocations and the movement of grain boundaries due to the deformation. The effect of the finely dispersed particles is generally greater as the abundance of the particles is larger, and is larger as the content is the same and the diameter is smaller and the particles are uniformly dispersed. However, the presence of fine particles increases the deformation resistance when molding a tube or the like, deteriorates the deformability and deteriorates the workability, and makes it difficult to soften the work-hardened material by annealing.
【0005】原子炉の燃料被覆管を製造する場合、まず
酸化物分散型合金とするため、合金粉末と酸化物粉末と
をボールミルなどで十分に粉砕混合し、いわゆるメカニ
カルアロイイングした後、例えば円筒形状をした軟鋼製
のカプセルに封入し、これを熱間押出しして、素管に固
化成形する。この素管は2ロール型のピルガーミルまた
は3ロール型のHPTRミルを用いて冷間圧延され、所
要寸法に製管される。寸法精度を厳しく要求される燃料
被覆管は、細径薄肉であるために、加工度の大きい冷間
加工をおこなわなければならない。In the case of producing a fuel cladding tube for a nuclear reactor, first, in order to obtain an oxide dispersion type alloy, the alloy powder and the oxide powder are sufficiently pulverized and mixed in a ball mill or the like, and after so-called mechanical alloying, for example, a cylinder is used. It is encapsulated in a shaped mild steel capsule, which is hot extruded and solidified into a raw tube. This raw pipe is cold-rolled using a two-roll type Pilger mill or a three-roll type HPTR mill, and produced into a required size. Since the fuel cladding tube, which is strictly required to have dimensional accuracy, has a small diameter and thin wall, it must be cold-worked with a high degree of workability.
【0006】ところが、微細な酸化物粒子が分散した合
金の場合、強度の冷間圧延によって加工方向に伸びた繊
維状組織が焼鈍後も強く残存し、その結果、長さ方向へ
の応力には高い強さを示すが、それに直交する方向の応
力には極めて弱い管となる。燃料被覆管では内圧クリー
プ強さを要求されるので、この半径方向ないしは管の円
周方向の強さ向上は、実用化へ向けての大きな課題であ
る。However, in the case of an alloy in which fine oxide particles are dispersed, the fibrous structure elongated in the working direction due to the strong cold rolling remains strongly even after annealing, and as a result, the stress in the length direction is reduced. Although it has high strength, the tube is extremely weak against stress in the direction orthogonal to it. Since the internal pressure creep strength is required for the fuel cladding tube, the improvement of the strength in the radial direction or the circumferential direction of the tube is a major issue for practical use.
【0007】これに対し、加工後の熱処理を十分におこ
なって結晶粒を粗大化させ、加工方向に直角の方向にも
粒が成長した再結晶組織にすると、この半径方向の強さ
が長さ方向のそれに近づき、内圧クリープ強さは向上す
ることが知られている(鵜飼、他:「まてりあ」vol.39
(2000),No.1,p78)。また、特開平8-225891号公報に
は、この酸化物分散型フェライト系高クロム鉄合金のY
2O3の含有量を0.3%以下とし、加えて過剰酸素の量
を限定することにより、結晶粒を粗大化させる温度を13
00℃以下にする発明が開示されており、実施例では1200
℃の焼鈍結果が示されている。On the other hand, when the heat treatment after the working is sufficiently performed to coarsen the crystal grains to form a recrystallized structure in which the grains grow in the direction perpendicular to the working direction, the strength in the radial direction is long. It is known that the creep strength of internal pressure improves as it approaches the direction (Ukai, et al .: "Materia" vol.39).
(2000), No.1, p78). Further, in Japanese Patent Laid-Open No. 8-225891 , Y of the oxide-dispersed ferrite high chromium iron alloy is disclosed.
By setting the content of 2 O 3 to 0.3% or less and additionally limiting the amount of excess oxygen, the temperature for coarsening the crystal grains is set to 13
The invention is disclosed in which the temperature is set to 00 ° C. or lower, and in the examples, 1200
The results of annealing at ° C are shown.
【0008】しかしながら、酸化物分散強化型フェライ
ト系高クロム鉄合金を用い、実寸法の燃料被覆管を製造
してみると、内圧クリープ強さないしは周方向方向の高
温強さの十分すぐれた管を安定して得ることは必ずしも
容易ではない。とくに酸化物の分散強化効果を十分得る
ために、その含有量を増し分散をよくするほど長さ方向
と周方向の強度差が増し、その製造条件のより一層の改
善が必要であると考えられた。[0008] However, when an oxide-dispersion-strengthened ferritic high chromium iron alloy is used to manufacture a fuel clad pipe of an actual size, it is possible to obtain a pipe having an internal pressure creep strength or a high temperature strength in the circumferential direction. Getting stable is not always easy. In particular, in order to sufficiently obtain the effect of strengthening the dispersion of the oxide, the strength difference between the length direction and the circumferential direction increases as the content is increased and the dispersion is improved, and it is considered that further improvement of the manufacturing conditions is required. It was
【0009】[0009]
【発明が解決しようとする課題】本発明の目的は、圧延
加工および焼鈍を繰返おこなって製造される酸化物分散
強化型フェライト系高クロム鉄合金管において、圧延の
長さ方向とそれに直交する周方向との強さの異方性を少
なくし、かつ内圧クリープ強さのレベルを向上させる方
法を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide an oxide dispersion strengthened ferritic high chromium iron alloy pipe manufactured by repeating rolling and annealing, which is perpendicular to the rolling length direction. It is to provide a method for reducing the anisotropy of strength with respect to the circumferential direction and improving the level of internal pressure creep strength.
【0010】[0010]
【課題を解決するための手段】本発明者らは、主として
クロムが質量%にて11〜15%、WおよびMoの合計が4
%以下、Tiが1%以下で、Y2O3を含む微細な酸化
物粒子の分散により強化を図った、分散強化型フェライ
ト系高クロム鉄合金による原子炉燃料被覆管の性能向
上、とくに管の周方向の高温強さを安定して向上させる
べく、その製造条件の検討をおこなった。SUMMARY OF THE INVENTION The inventors of the present invention have found that mainly chromium is 11 to 15% by mass, and the sum of W and Mo is 4%.
%, Ti less than 1%, and enhanced performance by dispersion of fine oxide particles containing Y 2 O 3 ; improvement of performance of reactor fuel cladding tube by dispersion strengthening ferritic high chromium iron alloy, especially tube In order to stably improve the high temperature strength in the circumferential direction, the manufacturing conditions were examined.
【0011】まず始めに、熱間押出しにて得られた素管
により、約50%の冷間圧延と温度を種々変えた焼鈍とを
それぞれ2回おこなって合金管を作製し、長さ方向に対
して直交する、管の内径を拡大させる方向のクリープ強
さを調査した。その結果、1回目の焼鈍すなわち圧延と
圧延の間の中間焼鈍の温度を低くし、2回目の焼鈍すな
わち最終焼鈍の温度を高くすることにより、この長さ方
向に対して直交方向の強さが著しく劣る傾向は改善さ
れ、金属組織が結晶粒の大きい組織となることが確認で
きた。First, an alloy tube was produced by performing cold rolling at about 50% and annealing at various temperatures twice twice using a raw tube obtained by hot extrusion to prepare an alloy tube in the length direction. The creep strength, which is perpendicular to the direction of increasing the inner diameter of the tube, was investigated. As a result, by lowering the temperature of the first annealing, that is, the intermediate annealing between rolling, and increasing the temperature of the second annealing, that is, the final annealing, the strength in the direction orthogonal to this length direction is increased. It was confirmed that the tendency of remarkably inferiority was improved and that the metallographic structure became a structure with large crystal grains.
【0012】一般に高温におけるクリープ変形は、結晶
粒界の滑りによって生じるので、応力の加わる方向を横
切る結晶粒界の数が少ないほど、高温強さのすぐれたも
のになる。したがって冷間加工により細粒化された管の
周方向に対しても、結晶粒を大きく成長させた金属組織
がより好ましい結果をもたらしたものと思われる。Generally, creep deformation at a high temperature is caused by the sliding of crystal grain boundaries. Therefore, the smaller the number of crystal grain boundaries crossing the direction in which stress is applied, the better the high temperature strength. Therefore, it is considered that the metal structure in which the crystal grains are grown large has brought more preferable results even in the circumferential direction of the tube finely grained by cold working.
【0013】実際の原子炉燃料被覆管は細径薄肉である
ため、熱間押出しにより得られた素管から冷間圧延と軟
化のための中間焼鈍とを2〜3回ないしはそれ以上繰返
してから、最終の冷間圧延および焼鈍をおこなって製造
しなければならない。そこで上述の2回の冷間圧延およ
び焼鈍の実験にて好ましいと考えられた条件に基づき、
焼鈍条件などを選定して製造したところ、製造した管の
内圧クリープ強さは、十分高いものが必ずしも安定して
得られなかったのである。Since an actual reactor fuel cladding tube is thin and thin, it is necessary to repeat cold rolling and intermediate annealing for softening 2-3 times or more from a raw tube obtained by hot extrusion. , Final cold rolling and annealing must be performed. Therefore, based on the conditions considered to be preferable in the above-described two cold rolling and annealing experiments,
When manufacturing was performed by selecting the annealing conditions, etc., the internal pressure creep strength of the manufactured pipe was not always sufficiently stable and could not be obtained.
【0014】この原因を明らかにするため、合計3回以
上の冷間圧延と焼鈍とを繰返して製造された管につい
て、長さ方向に平行な縦断面の金属組織を調査した結
果、次のようなことがわかった。In order to clarify the cause of this, as a result of investigating the metallographic structure of the longitudinal section parallel to the length direction of the pipe manufactured by repeating cold rolling and annealing at least three times in total, the following results were obtained. I found out.
【0015】焼鈍後の管の長さ方向に平行な断面の光学
顕微鏡組織には、典型的な例として図1に示すような4
つの組織が観察された。(a)は焼鈍温度がやや低いと
きによく見られる例で、加工状態に比して硬さは低下し
ているが、光学顕微鏡観察では加工のままとほとんど差
がない。この組織の管は、強さの異方性が大きく内圧ク
リープ強さが劣る。これに対し(c)は焼鈍温度を十分
高くした場合の例で、粗大な粒からなる組織のこの管
は、多くの場合、強さの異方性は小さくすぐれた高温内
圧クリープ強さを示す。The optical microscope structure of the cross section parallel to the length direction of the tube after annealing has a typical structure as shown in FIG.
Two tissues were observed. (A) is an example that is often seen when the annealing temperature is slightly low, and the hardness is lower than that in the processed state, but there is almost no difference from the as-processed state by observation with an optical microscope. The tube of this structure has large anisotropy of strength and poor internal creep strength. On the other hand, (c) shows an example in which the annealing temperature is sufficiently high. In many cases, this tube having a structure composed of coarse grains has excellent anisotropy of strength and excellent high-temperature internal pressure creep strength. .
【0016】圧延後焼鈍した管の組織には、図1(b)
に示すような、微細な組織の中に、(c)の組織の粗大
粒に相当すると推測される大きな結晶粒が観察されるこ
とがある。これは、一般的に、再結晶における粒成長の
粒界移動が微細析出物により強く拘束されたときに生じ
る、不均一な粒成長の過程に観察される現象であり、全
体がこれらの粗大粒のみになったと推定される(c)の
組織は、いわゆる二次再結晶組織であることを示してい
る。The structure of the tube annealed after rolling is shown in FIG.
Large crystal grains that are supposed to correspond to the coarse grains of the structure of (c) may be observed in the fine structure as shown in FIG. This is a phenomenon generally observed in the process of non-uniform grain growth that occurs when grain boundary movement of grain growth during recrystallization is strongly restrained by fine precipitates, and the whole of these coarse grains is observed. The structure of (c) which is presumed to have become the only one shows that it is a so-called secondary recrystallization structure.
【0017】通常、金属を冷間加工し硬化した状態で
は、加工方向に延伸した加工組織になっている。これを
軟化するために加熱すると、加工により生じた歪みや転
位の移動再整理段階である回復、再結晶核生成、成長、
再結晶組織形成という再結晶現象が進行する。このよう
な再結晶過程の進行は、硬さなど機械的性質の変化とし
て検知でき、それとともに、金属組織の変化を光学顕微
鏡により見ることができる。Usually, in the state where the metal is cold worked and hardened, the working structure is stretched in the working direction. When it is heated to soften it, the strain, dislocation movement and rearrangement caused by processing, that is, recovery, recrystallization nucleation, growth,
A recrystallization phenomenon called recrystallization texture formation progresses. Such progress of the recrystallization process can be detected as a change in mechanical properties such as hardness, and at the same time, a change in metal structure can be observed by an optical microscope.
【0018】しかし、微細粒子が分散存在する合金の場
合、転位や結晶粒界の移動が微細粒子によって大きく阻
害されるため、上記の再結晶過程は容易には進行せず、
その上、通常の意味での再結晶現象が生じたとしても、
光学顕微鏡観察では加工組織との相違がほとんど区別で
きない。光学顕微鏡観察では相違がなくても、硬さは低
下しており、さらなる加工が可能な状態に延性が回復し
ているので、再結晶は進行していると推定される。However, in the case of an alloy in which fine particles are dispersedly present, dislocations and movements of crystal grain boundaries are largely hindered by the fine particles, so that the above recrystallization process does not easily proceed,
Moreover, even if a recrystallization phenomenon occurs in the usual sense,
The difference with the processed structure can hardly be distinguished by observation with an optical microscope. Even if there is no difference by optical microscope observation, the hardness is lowered, and the ductility is restored to a state in which further processing is possible, so it is presumed that recrystallization is in progress.
【0019】さらに温度を上げていくと、微細な組織の
中から特定の粒のみが成長し、これが周囲の微細組織を
蚕食して粗大粒となり、やがては全体が粗大粒組織にな
る。これは、一般的には二次再結晶または異常粒成長と
呼ばれる現象であり、上記の酸化物分散型合金において
は、この段階に至らなければ光学顕微鏡観察にて組織変
化が検知できない。When the temperature is further increased, only specific grains grow out of the fine structure, which eclipse the surrounding fine structure to form coarse grains, and eventually the whole becomes coarse grain structure. This is a phenomenon generally called secondary recrystallization or abnormal grain growth, and in the above oxide dispersion type alloy, a microstructural change cannot be detected by optical microscope observation until this stage.
【0020】そこで、ここではこの二次再結晶を再結
晶、それによってできた(c)の組織を再結晶組織、そ
して二次再結晶前の軟化した再結晶状態、すなわち一般
的には一次再結晶と呼ばれる(a)の状態の組織を、回
復組織と呼ぶことにする。したがって、(b)のような
組織は部分再結晶組織ということになるが、この組織で
は(a)と同様、強さの異方性が大きく内圧クリープ強
さが劣る管となる。Therefore, here, this secondary recrystallization is recrystallized, the resulting structure (c) is recrystallized, and the softened recrystallized state before the secondary recrystallization, that is, generally the primary recrystallization is performed. The structure in the state (a) called a crystal is called a recovery structure. Therefore, the structure as shown in (b) is a partially recrystallized structure, but this structure has a large anisotropy of strength and a poor internal pressure creep strength as in (a).
【0021】観察された組織の中には(d)に示したよ
うに、変形帯が残った部分と、加工のまま、ないしは回
復組織に近い状態の部分とが、帯状に伸びて隣接してい
るものがある。焼鈍温度を高くしても、この状態は容易
には解消されない。これをさらに調べてみると、中間焼
鈍の段階で焼鈍で粗大な再結晶組織になり、これが引き
続いて冷間圧延され最終焼鈍されたものであることがわ
かった。圧延前の粗大粒が伸ばされ、元の個々の粗大粒
に対応する部分が同じ挙動を示し、焼鈍後変形のまま
か、回復状態にまで進んでとまっているものと思われ
る。粗大粒組織となった後の加工では、粒内の滑り変形
が主となって十分な歪みの蓄積がおこなわれず、通常の
再結晶が進行しなくなり、二次再結晶である本発明でい
う再結晶が生じなくなってしまったと推定される。この
ような組織の管は、内圧クリープ強さが低く強さの異方
性も大きい。In the observed structure, as shown in (d), the part where the deformation band remains and the part which is in the state of being processed or in the state close to the recovered structure are stretched in a band shape and adjacent to each other. There is something. Even if the annealing temperature is increased, this state cannot be easily resolved. Further investigation of this revealed that the intermediate re-annealing resulted in a coarse recrystallized structure, which was subsequently cold-rolled and finally annealed. It is considered that the coarse grains before rolling are stretched, and the parts corresponding to the original individual coarse grains show the same behavior, and remain in the deformed state after annealing or have progressed to the recovery state. In the processing after the coarse grain structure is obtained, sufficient deformation is not accumulated mainly due to slip deformation within the grain, and normal recrystallization does not proceed, and the recrystallization referred to in the present invention as secondary recrystallization. It is presumed that crystals have disappeared. The tube having such a structure has low internal pressure creep strength and large strength anisotropy.
【0022】中間焼鈍後にこの再結晶組織となった場
合、さらに冷間圧延し焼鈍すると再結晶組織と同様な組
織になることもあるが、そのような管は強さが低く異方
性も大きい傾向を示す。When this recrystallized structure is obtained after the intermediate annealing, it may be the same structure as the recrystallized structure by further cold rolling and annealing, but such a tube has low strength and large anisotropy. Show a trend.
【0023】素管に対する1回目の冷間圧延および焼鈍
にて粗大粒が現れなくても、引き続く冷間圧延の後に同
じ条件でもう一度焼鈍すると、再結晶組織になってしま
うことがあり、冷間圧延と中間焼鈍を繰返しおこなう場
合は、焼鈍温度の選定に十分注意しなければならない。
これは、圧延と焼鈍とを繰返すことにより、微細な酸化
物粒子が凝集や粗大化して、転位や結晶粒界の移動を阻
害する効果が減退していくためと考えられる。Even if coarse grains do not appear in the first cold rolling and annealing of the blank, if reannealed under the same conditions after the subsequent cold rolling, a recrystallized structure may be formed. When rolling and intermediate annealing are repeated, sufficient care must be taken in selecting the annealing temperature.
It is considered that this is because by repeating rolling and annealing, fine oxide particles aggregate and coarsen, and the effect of inhibiting dislocation and movement of crystal grain boundaries diminishes.
【0024】以上のような調査結果から、中間焼鈍の段
階で再結晶組織や部分再結晶組織が現れたときには、た
とえ最終の冷間圧延および焼鈍後に再結晶組織を示した
としても、得られた管の内圧クリープ強さは低いことが
わかった。すなわち、圧延途中の焼鈍では、十分軟化で
きる条件でなければならないが、粗大粒を出現させては
よくないのである。From the above investigation results, when a recrystallized structure or a partial recrystallized structure appeared in the intermediate annealing stage, it was obtained even if the recrystallized structure was shown after the final cold rolling and annealing. It was found that the internal pressure creep strength of the pipe was low. That is, in the annealing during rolling, the condition must be such that it can be sufficiently softened, but it is not good to allow coarse grains to appear.
【0025】中間焼鈍は、加工硬化した被圧延材の加工
性を回復するためにおこなうものであるが、上述のよう
にその温度は高くしないことが望ましい。しかし、焼鈍
温度の低下は軟化不足をきたし、次工程の圧延加工を困
難にする。これに対しては、冷間圧延の加工度はできる
だけ大きくすることが、低い温度でも十分に軟化させる
ために重要であることが確認された。The intermediate annealing is carried out in order to recover the workability of the work-hardened material to be rolled, but it is desirable not to raise the temperature as described above. However, the lowering of the annealing temperature causes insufficient softening, which makes the rolling process in the next step difficult. On the other hand, it was confirmed that it is important to make the cold rolling workability as large as possible in order to sufficiently soften even at a low temperature.
【0026】上述のような検討は、主として、クロムが
11〜15%、Y2O3を0.2%程度含む、フェライト系鉄
合金を対象におこなったが、さらに多くクロムを含む場
合、あるいは微細に分散した酸化物がY2O3以外であ
る場合に対して検討した結果、これらの合金においても
同様な結果が認められた。すなわち耐熱用途を目的とし
た、酸化物を微細に分散させたクロムを含むフェライト
系鉄合金を用い、多数回の冷間加工および焼鈍を繰返し
て所要寸法の管を製造する場合、圧延途中の焼鈍すなわ
ち中間焼鈍は温度を1100℃未満と低くして、上述のよう
な再結晶組織になることを抑止し、最終焼鈍は1100℃以
上と高くして結晶粒径の大きな再結晶組織にさせる。そ
うすれば、圧延された長さ方向ばかりでなく、圧延に対
して直角の周方向にも十分な強度を有する合金管が、安
定して得られることがわかったのである。The above-mentioned investigations are mainly conducted on chromium.
The target was a ferritic iron alloy containing 11 to 15% and Y 2 O 3 of about 0.2%, but when more chromium was contained or when the finely dispersed oxide was other than Y 2 O 3. As a result of the examination, similar results were found in these alloys. That is, when a ferritic iron alloy containing chromium in which oxides are finely dispersed is used for the purpose of heat resistance, and cold-working and annealing are repeated many times to produce a tube of a required size, annealing during rolling is performed. That is, the intermediate annealing lowers the temperature to less than 1100 ° C. to prevent the recrystallization structure as described above from occurring, and the final annealing increases the temperature to 1100 ° C. or more to obtain the recrystallization structure having a large crystal grain size. By doing so, it was found that an alloy pipe having sufficient strength not only in the rolled length direction but also in the circumferential direction perpendicular to the rolling can be stably obtained.
【0027】以上のような知見に基づき、さらに限界条
件を確認して本発明を完成させた。本発明の要旨は次の
とおりである。Based on the above findings, the present invention was completed by further confirming the limiting conditions. The gist of the present invention is as follows.
【0028】(1) 質量%にてCr:11〜15%、Ti:0.
1〜1%およびY 2 O 3 :0.15〜0.35%を含む酸化物分散
強化型フェライト系鉄合金管の製造方法であって、金属
粉末と酸化物粉末との混合焼結により素材を作製し、合
計3回以上の冷間圧延および焼鈍を繰返して所要形状の
管にする際に、各冷間圧延の圧延率は30%以上、圧延途
中の焼鈍は1100℃未満、最終の焼鈍は1100℃以上でおこ
なうことを特徴とする、クロムを含む酸化物分散強化型
フェライト系鉄合金管の製造方法。(1) Cr: 11 to 15%, Ti: 0.
1-1% and Y 2 O 3: oxide dispersion containing from 0.15 to 0.35%
A method of manufacturing a reinforced ferritic iron alloy tube, which comprises producing a material by mixing and sintering metal powder and oxide powder, and repeating cold rolling and annealing at least three times to obtain a tube having a required shape. In this case, the rolling ratio of each cold rolling is 30% or more, the annealing during rolling is less than 1100 ° C, and the final annealing is performed at 1100 ° C or more. Method for manufacturing alloy pipe.
【0029】(2)質量%にてCr:11〜15%、Ti:0.1
〜1%、WおよびMoの1種または2種の合計:0.1〜4
%、ならびにY 2 O 3 :0.15〜0.35%を含む酸化物分散
強化型フェライト系鉄合金管の製造方法であって、金属
粉末と酸化物粉末との混合焼結により素材を作製し、合
計3回以上の冷間圧延および焼鈍を繰返して所要形状の
管にする際に、各冷間圧延の圧延率は30%以上、圧延途
中の焼鈍は1100℃未満、最終の焼鈍は1100℃以上でおこ
なうことを特徴とする、クロムを含む酸化物分散強化型
フェライト系鉄合金管の製造方法。(2) Cr: 11 to 15%, Ti: 0.1% by mass
~ 1%, the sum of one or two of W and Mo: 0.1 to 4
%, And Y 2 O 3 : oxide dispersion containing 0.15 to 0.35%
A method of manufacturing a reinforced ferritic iron alloy tube, which comprises producing a material by mixing and sintering metal powder and oxide powder, and repeating cold rolling and annealing at least three times to obtain a tube having a required shape. In this case, the rolling ratio of each cold rolling is 30% or more, the annealing during rolling is less than 1100 ° C, and the final annealing is performed at 1100 ° C or more. Method for manufacturing alloy pipe.
【0030】[0030]
【0031】[0031]
【発明の実施の形態】本発明の方法は、酸化物を分散強
化させたフェライト系の鉄合金管の製造に適用する。こ
のような合金管は、酸化物微細粒子の均一分散を図るた
め、金属粉末と酸化物粉末との混合焼結により素管を作
製し、これを冷間圧延および焼鈍を繰返して所要形状に
成形する。この製造過程では、素管を合計3回以上の冷
間圧延および焼鈍を繰返して所要形状の管とするが、そ
の際に、各回の冷間圧延の圧延率は30%以上、圧延途中
の焼鈍は1100℃未満、最終の焼鈍は1100℃以上とするも
のである。BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention is applied to the production of a ferrite-based iron alloy tube dispersion-strengthened with an oxide. In order to uniformly disperse oxide fine particles, such alloy pipes are made by mixing and sintering metal powder and oxide powder to form a raw pipe, which is repeatedly cold-rolled and annealed to form the required shape. To do. In this manufacturing process, cold rolling and annealing are repeated three times or more in total to form a pipe having a required shape. At that time, the rolling ratio of each cold rolling is 30% or more, and the annealing in the middle of rolling is performed. Is below 1100 ° C, and the final annealing is above 1100 ° C.
【0032】素管の製造は、例えば、まず所要組成の金
属粉末および酸化物粉末を、ボールミル等を用い、いわ
ゆるメカニカルアロイイングの手法により十分粉砕混合
する。次にこの粉末を軟鋼カプセル等に封入して、加熱
押出しにより一体化焼結して冷間圧延加工用素管を作製
する。要すればこれをさらに加熱焼鈍して冷間加工用素
材とする。この段階までの製造は、従来実施されている
技術に準じておこなえばよい。In the production of the raw tube, for example, first, a metal powder and an oxide powder having a required composition are sufficiently pulverized and mixed by a so-called mechanical alloying method using a ball mill or the like. Next, this powder is enclosed in a mild steel capsule or the like, and is integrally sintered by heat extrusion to produce a cold-rolling base pipe. If necessary, this is further annealed by heating to obtain a material for cold working. The manufacturing up to this stage may be performed according to a conventionally practiced technique.
【0033】素管の冷間圧延は、ピルガー圧延機または
HPTR圧延機を用いるのが望ましい。これは比較的硬
い材料に対し冷間ないしは温間で、大きな成形比の加工
が可能だからである。冷間圧延の圧延率(断面減少率)
は30%以上が必要である。ここで、冷間圧延の圧延率と
は、素管または焼鈍後の軟化状態から圧延を開始して、
次の軟化のための中間焼鈍または最終焼鈍をおこなうま
での間の圧延の合計の圧延率であり、1パスで30%以上
の圧延でもよく、2パス、3パスと複数パス圧延して30
%以上としてもよい。For the cold rolling of the blank, it is desirable to use a Pilger rolling machine or an HPTR rolling machine. This is because a relatively hard material can be processed cold or warm with a large forming ratio. Cold rolling reduction rate (area reduction rate)
Needs more than 30%. Here, the rolling ratio of the cold rolling, starting the rolling from the raw tube or the softened state after annealing,
It is the total rolling ratio of rolling until the intermediate annealing or the final annealing for the next softening, and the rolling may be 30% or more in one pass, or 30 in two passes, three passes or multiple passes.
% Or more may be used.
【0034】圧延率30%以上の冷間圧延を施すのは、圧
延途中での軟化焼鈍すなわち中間焼鈍の加熱温度を低下
させることができ、さらに最終圧延後に再結晶組織とす
るための加熱温度も低くすることができるからである。
より安定して焼鈍温度低下の効果を得るためには、この
冷間圧延の圧延率を40%以上とするのが望ましい。The cold rolling with a rolling ratio of 30% or more can lower the heating temperature of softening annealing during rolling, that is, the intermediate annealing, and also the heating temperature for forming a recrystallized structure after the final rolling. This is because it can be lowered.
In order to obtain the effect of lowering the annealing temperature more stably, it is desirable that the rolling ratio of this cold rolling be 40% or more.
【0035】圧延加工途中の中間焼鈍は1100℃未満の温
度とする。これは1100℃以上の温度になると再結晶組織
ないしは部分再結晶組織になるおそれがあり、ことに圧
延と軟化焼鈍が繰返されるとその危険性が増大するから
である。ただし焼鈍の加熱温度は低すぎると軟化が不十
分となり、その後での30%を超える圧延が困難になって
くるので、1000℃以上にするのがよい。The intermediate annealing during the rolling process is performed at a temperature of less than 1100 ° C. This is because a temperature of 1100 ° C. or higher may cause a recrystallized structure or a partial recrystallized structure, and in particular, if rolling and softening annealing are repeated, the risk increases. However, if the annealing heating temperature is too low, the softening becomes insufficient and it becomes difficult to roll more than 30% thereafter.
【0036】最終の焼鈍は、再結晶組織とするために11
00℃以上の加熱が必要である。1100℃未満では再結晶組
織が十分に形成されず、強さの異方性が減少しないおそ
れがある。しかし、1250℃を超える加熱は、異方性が低
減できてもクリープ強さが低くなってしまうことがあ
り、1150〜1250℃の範囲とするのが望ましい。The final annealing was performed to obtain a recrystallized structure.
Heating above 00 ℃ is required. If it is less than 1100 ° C, the recrystallized structure is not sufficiently formed, and the anisotropy of strength may not be reduced. However, heating above 1250 ° C may lower the creep strength even if the anisotropy can be reduced, and it is desirable to set the temperature in the range of 1150 to 1250 ° C.
【0037】上記各焼鈍の加熱時間は、途中の軟化焼鈍
でも最終の焼鈍でも、10分以上2時間程度その温度に保
持すれば、十分その目的を達することができる。The heating time of each of the above annealings, whether it is the softening annealing in the middle or the final annealing, can be sufficiently achieved by maintaining the temperature for 10 minutes or more and 2 hours.
【0038】本発明方法のこの圧延と焼鈍の条件は、圧
延と中間および最終の焼鈍とを合計3回以上繰返す場合
にとくに効果がある。2回の場合は中間焼鈍を上記のよ
うに1100℃未満にしなくても、この段階で再結晶組織が
現れないことが多い。しかし、燃料被覆管の場合、細径
薄肉のため3回以上の圧延と焼鈍の繰返しが必要であ
り、圧延と焼鈍との繰返し回数が増すと、最終の圧延前
に再結晶組織が現れる危険性が増してくる。The rolling and annealing conditions of the method of the present invention are particularly effective when rolling and intermediate and final annealing are repeated a total of three times or more. In the case of twice, even if the intermediate annealing is not performed at less than 1100 ° C as described above, the recrystallized structure often does not appear at this stage. However, in the case of a fuel clad tube, rolling and annealing must be repeated three times or more due to its small diameter and thin wall, and if the number of rolling and annealing is increased, there is a risk that a recrystallized structure will appear before the final rolling. Is increasing.
【0039】本発明の対象とする管は、素材が合金粉末
と酸化物粉末とを混合焼結したもので、Cr:11〜15%
およびTi:0.1〜1%、または更に、WおよびMoの1
種または2種の合計:0.1〜4%を含み、酸化物を分散さ
せて強化した、フェライト系の耐熱鉄合金製のものであ
る。合金中に分散させる微細な酸化物粒子としては、Y
2 O 3 :0.15〜0.35%を含むものである。その他、Mg
O、Al2O3、MgAl2O4、ThO2、TiO 2
およびZrO 2 の1種または2種以上を含むものであっ
てもよい。そして、いずれの酸化物の微細粒子の分散で
あっても、それによって合金管の高温強度向上を図る場
合、本発明の方法の適用が強度向上や強度の異方性低減
に効果を発揮する。The tube to which the present invention is applied is made by mixing and sintering alloy powder and oxide powder, and Cr: 11-15%
And Ti: 0.1 to 1%, or even 1 of W and Mo
Made of a ferritic heat-resistant iron alloy containing 0.1 to 4% of a total of 0.1 to 4% and reinforced by dispersing an oxide.
It The fine oxide particles dispersed in the alloy include Y
2 O 3 : It contains 0.15 to 0.35%. Others, Mg
O, Al 2 O 3, MgAl 2 O 4, ThO 2, Ti O 2
It is those and including one or more of Zr O 2
May be . In order to improve the high temperature strength of the alloy tube by using any of the oxide fine particles dispersed therein, the application of the method of the present invention is effective in improving the strength and reducing the anisotropy of the strength.
【0040】本発明の製造方法を適用して最も効果のあ
る合金管の一つは、Crを11〜15%(以下いずれも質量
%)、Tiを0.1〜1%、Y2O3を0.15〜0.35%含有す
る、酸化物分散強化型フェライト系鉄合金管である。な
お、合金中にはこれら成分に加えて、フェライト系鉄合
金に添加される他の合金成分を含んでいてもよい。One of the most effective alloy pipes to which the manufacturing method of the present invention is applied is that Cr is 11 to 15% (hereinafter, all are mass%), Ti is 0.1 to 1%, and Y 2 O 3 is 0.15. An oxide dispersion strengthened ferritic iron alloy tube containing ~ 0.35%. In addition to these components, the alloy may contain other alloy components added to the ferritic iron alloy.
【0041】この場合、Crの含有量は11%未満では耐
酸化性や耐食性が不足であり、15%を超えると中性子照
射などによる脆化が起こりやすくなるため、11〜15%と
するのがよい。TiはY2O3など酸化物粒子を微細化
させる作用があり、0.1〜1%の範囲で含有させるのが好
ましい。これは、0.1%未満ではその効果が小さく、1%
を超えるとその効果は飽和してしまうからである。In this case, if the Cr content is less than 11%, the oxidation resistance and corrosion resistance are insufficient, and if it exceeds 15%, embrittlement due to neutron irradiation or the like tends to occur. Good. Ti has a function of refining oxide particles such as Y 2 O 3, and is preferably contained in the range of 0.1 to 1%. This is less than 0.1%, the effect is small, 1%
If it exceeds, the effect will be saturated.
【0042】分散させる酸化物としては、Y2O3を0.
15〜0.35%含ませるが、Y2O3は容易に微細に分散
し、かつ高温強さを向上させるのに極めて有効な酸化物
である。その含有量は、0.15%を下回る場合、圧延途中
の軟化処理の過程で再結晶組織を生じやすく、その結果
として最終焼鈍後に強さの異方性が大きい状態になりや
すい。しかし、含有量が0.35%を超えると、再結晶組織
を得るのに要する焼鈍温度が高くなり、加工も困難にな
ってくる。したがってY2O3の含有量は0.15〜0.35%
がよい。しかし、強さの異方性が大きくならない範囲で
より高温強さが高い管にするには、0.20〜0.35%とする
のが望ましい。As the oxide to be dispersed, Y 2 O 3 of 0.
Although it is contained in an amount of 15 to 0.35%, Y 2 O 3 is an oxide that is extremely effective for easily finely dispersing and improving high temperature strength. If the content is less than 0.15%, a recrystallized structure is likely to occur during the softening process during rolling, and as a result, the strength anisotropy tends to be large after the final annealing. However, if the content exceeds 0.35%, the annealing temperature required to obtain the recrystallized structure becomes high and the working becomes difficult. Therefore, the content of Y 2 O 3 is 0.15 to 0.35%
Is good. However, 0.20 to 0.35% is desirable in order to obtain a tube having high strength at high temperature within a range where strength anisotropy does not increase.
【0043】上記のフェライト系鉄合金管の高温強さ
を、酸化物微粒子分散のように加工性の大幅劣化や異方
性を生じることなく、向上させる元素としてWおよびM
oの1種または2種を合計量で0.1〜4%含有してもよ
い。この場合0.1%未満では添加の効果はなく、4%を超
えると加工性が悪くなる。W and M are used as elements for improving the high temperature strength of the above-mentioned ferritic iron alloy tube without causing significant deterioration of workability and anisotropy unlike the dispersion of oxide fine particles.
One or two kinds of o may be contained in a total amount of 0.1 to 4%. In this case, if it is less than 0.1%, there is no effect of addition, and if it exceeds 4%, the workability deteriorates.
【0044】[0044]
【実施例】鉄基合金粉末にY2O3の粉末を混ぜ、アト
ライタボールミルにてアルゴン雰囲気中で粉砕混合し、
得られた粉末を軟鋼製カプセルに封入して1150℃に加熱
し、押出し比7として外径約20mmの合金棒を作製した。
これから外径18mm、肉厚3mmの素管を機械加工にて削り
だし、1250℃にて30分の焼鈍をおこなって冷間圧延用素
管とした。作製した3種の素管の化学組成を表1に示
す。[Examples] Y 2 O 3 powder was mixed with iron-based alloy powder, and pulverized and mixed in an argon atmosphere with an attritor ball mill,
The obtained powder was enclosed in a mild steel capsule and heated to 1150 ° C. to produce an alloy rod having an extrusion ratio of 7 and an outer diameter of about 20 mm.
From this, a blank pipe having an outer diameter of 18 mm and a wall thickness of 3 mm was machined out and annealed at 1250 ° C. for 30 minutes to obtain a cold-rolled blank pipe. Table 1 shows the chemical compositions of the three types of prepared tube.
【0045】[0045]
【表1】 [Table 1]
【0046】これらの素管を用い、図2に示す工程に
て、〜の冷間圧延と焼鈍とを繰返して外径7.1mm、
肉厚0.53mmの合金管を作製した。冷間圧延はピルガー圧
延機を用い、1パスにて45〜48%の加工をおこなった。
圧延加工の途中で施す3回の中間焼鈍は、一つの管の圧
延に対しては同一温度の繰返とし、1050℃、1100℃、11
50℃または1200℃の4温度とした。最終焼鈍はいずれも1
150℃である。これらの焼鈍の均熱時間はいずれも30分
とした。各焼鈍の後、管端部分より試片を切り出し、縦
断面の顕微鏡組織を観察した。Using these raw tubes, in the process shown in FIG. 2, the cold rolling and annealing of are repeated to obtain an outer diameter of 7.1 mm,
An alloy tube with a wall thickness of 0.53 mm was produced. For cold rolling, a Pilger rolling machine was used to perform 45 to 48% processing in one pass.
The three intermediate anneals performed during the rolling process are repeated at the same temperature for rolling one pipe, and 1050 ℃, 1100 ℃, 11
Four temperatures of 50 ° C or 1200 ° C were used. 1 for final annealing
It is 150 ℃. The soaking time for each of these annealings was 30 minutes. After each annealing, a test piece was cut out from the tube end and the microscopic structure of the longitudinal section was observed.
【0047】これらの顕微鏡組織は、図1にその例を示
した(a)回復組織、(b)部分再結晶組織、(c)再
結晶組織または(d)変形回復組織を示しており、中間
焼鈍温度との関係をまとめると図3のようになる。図3
には組織とともに硬さ(HV)の測定結果を示す。These microscopic structures show (a) recovered structure, (b) partial recrystallized structure, (c) recrystallized structure or (d) deformation recovered structure, examples of which are shown in FIG. The relationship with the annealing temperature is summarized in FIG. Figure 3
Shows the measurement results of hardness (HV) together with the tissue.
【0048】こここに示されるように、冷間圧延と中間
焼鈍とを繰返して管を製造すると、Y2O3の含有量の
少ない合金Aでは、中間焼鈍温度が1100℃以上と高い場
合、冷間圧延および焼鈍を繰返すうちに再結晶組織が生
じ、さらには変形回復組織が生じてしまう。中間焼鈍温
度が高ければ、圧延途中の段階で変形回復組織となって
も、最終的に再結晶組織にすることができる。このよう
に、中間焼鈍の段階にて再結晶組織が生じやすい場合で
も、1100℃未満である1050℃にて中間焼鈍をおこなえ
ば、この段階では再結晶組織とはならず、最終焼鈍後に
初めて再結晶組織を出現させることができる。しかしな
がら酸化物量の少ない合金Aでは、高温強度の向上が大
きくなく、強化の目的は十分達成できていない。As shown here, when a tube is manufactured by repeating cold rolling and intermediate annealing, alloy A having a small content of Y 2 O 3 has a high intermediate annealing temperature of 1100 ° C. or higher. A recrystallized structure is generated during repeated cold rolling and annealing, and further a deformation recovery structure is generated. If the intermediate annealing temperature is high, the recrystallized structure can be finally obtained even if the deformation recovery structure is formed in the middle of rolling. Thus, even if a recrystallized structure is likely to occur in the stage of intermediate annealing, if the intermediate annealing is performed at 1050 ° C, which is lower than 1100 ° C, the recrystallized structure does not occur at this stage, and the recrystallized structure is not regenerated after the final annealing. A crystalline structure can appear. However, with alloy A having a small amount of oxide, the improvement in high temperature strength is not significant, and the purpose of strengthening cannot be achieved sufficiently.
【0049】酸化物量の多い合金BおよびCにおいて
も、1100℃以上の中間焼鈍温度では、圧延途中で再結晶
組織が生じてしまい、最終焼鈍後には強さの異方性の大
きい変形回復組織になってしまう。これに対し、中間焼
鈍の温度を1100℃未満の1050℃とし、最終焼鈍にて1100
℃以上の1150℃とすることにより強さの異方性の小さい
再結晶組織で、十分な強度を有する管が得られる。Even in alloys B and C containing a large amount of oxides, at an intermediate annealing temperature of 1100 ° C. or higher, a recrystallization structure is generated during rolling, and after the final annealing, a deformation recovery structure having a large anisotropy of strength is formed. turn into. On the other hand, the temperature of the intermediate annealing is set to 1050 ° C, which is less than 1100 ° C, and the final annealing
By setting the temperature to 1150 ° C. or higher, a tube having a recrystallized structure with small strength anisotropy and having sufficient strength can be obtained.
【0050】上記の合金Bにて作製した、中間焼鈍が10
50℃で最終焼鈍にて再結晶組織となった管、および中間
焼鈍が1150℃で変形回復組織となった管の2種を用い
て、内圧クリープ破断試験をおこなった。試験温度を70
0℃とし、内圧を種々変えて破断に至るまでの時間を測
定した結果を図4に示す。Intermediate annealing made of the above alloy B has 10
An internal pressure creep rupture test was carried out using two types of tubes, a tube having a recrystallized structure by final annealing at 50 ° C and a tube having a deformation recovery structure at 1150 ° C. Test temperature 70
FIG. 4 shows the results of measuring the time until fracture at 0 ° C. with various internal pressures.
【0051】これから明らかなように、本発明の方法に
より再結晶組織とした管は、同じ内圧に対し、回復変形
組織である管よりも破断時間が10倍以上長くなってい
る。圧延途中の段階では再結晶組織を発生させず、最終
の焼鈍にて金属組織を再結晶組織としたことによる効果
である。As is apparent from the above, a tube having a recrystallized structure by the method of the present invention has a fracture time 10 times longer than that of a tube having a recovered deformed structure for the same internal pressure. This is an effect obtained by forming a recrystallized structure in the final annealing without generating a recrystallized structure during rolling.
【0052】[0052]
【発明の効果】本発明の製造方法によれば、圧延加工お
よび焼鈍を繰返して製造される酸化物分散強化型フェラ
イト系高クロム鉄合金管において、長さ方向とそれに直
交する周方向との強さの異方性を少なくし、強度を向上
させることができる。この合金管は、高温で強い中性子
照射の環境下で使用される高速炉の燃料被覆管に用いれ
ば、高温強度、とくに内圧クリ−プ強さにすぐれたもの
が得られ、高速炉の実用化に寄与する効果が大きい。According to the manufacturing method of the present invention, in an oxide dispersion strengthened ferritic high chromium iron alloy pipe manufactured by repeating rolling and annealing, the strength in the length direction and the circumferential direction orthogonal thereto is increased. It is possible to reduce the anisotropy of the thickness and improve the strength. If this alloy tube is used for a fuel cladding tube of a fast reactor used under high temperature and strong neutron irradiation environment, it will be excellent in high temperature strength, especially internal pressure creep strength, and will be put to practical use in a fast reactor. The effect of contributing to is great.
【図1】冷間圧延後の焼鈍によって得られる管の圧延方
向断面の顕微鏡組織の例を示す図である。FIG. 1 is a diagram showing an example of a microstructure of a cross section in a rolling direction of a tube obtained by annealing after cold rolling.
【図2】合金管の圧延工程を説明する図である。FIG. 2 is a diagram illustrating a rolling process of an alloy pipe.
【図3】合金管の中間焼鈍または最終焼鈍後における顕
微鏡組織変化を示す図である。FIG. 3 is a view showing a change in microstructure of an alloy tube after intermediate annealing or final annealing.
【図4】再結晶組織を有する管または回復変形組織を有
する管の、700℃におけるクリープ破断試験結果を示す
図である。FIG. 4 is a diagram showing a creep rupture test result at 700 ° C. of a tube having a recrystallization structure or a tube having a recovery deformation structure.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 FI C22C 38/28 C22C 38/28 G21C 3/07 GDF B22F 3/20 B 3/30 G21C 3/06 GDFP // B22F 3/20 3/30 V (72)発明者 鵜飼 重治 茨城県東茨城群大洗町成田町4002核燃料 サイクル開発機構大洗工学センター内 (72)発明者 小林 十思美 兵庫県尼崎市東向島西之町1番地住友金 属テクノロジー株式会社関西事業所内 (72)発明者 奥田 隆成 山口県下関市長府港町13番1号神鋼特殊 鋼管株式会社内 (72)発明者 藤原 優行 兵庫県神戸市中央区脇浜町1丁目5番8 号株式会社コベルコ科研内 (56)参考文献 特開 平9−53141(JP,A) 特開 平8−225891(JP,A) 特開2001−49335(JP,A) 特開2000−282101(JP,A) (58)調査した分野(Int.Cl.7,DB名) C21D 8/10 B22F 3/24 C22C 33/02,38/00 - 38/60 ─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. 7 Identification code FI C22C 38/28 C22C 38/28 G21C 3/07 GDF B22F 3/20 B 3/30 G21C 3/06 GDFP // B22F 3/20 3/30 V (72) Inventor Shigeharu Ukai 4002 Narita-cho, Oarai-cho, Higashi-Ibaraki, Ibaraki Prefecture Oarai Engineering Center, Nuclear Fuel Cycle Development Organization (72) Inventor Jusumi Kobayashi 1 Nishino-cho, Higashimukaijima, Amagasaki-shi, Hyogo Sumitomo Kin Genus Technology Co., Ltd. Kansai Plant (72) Inventor Takanari Okuda 13-1 Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Shinko Special Steel Tube Co., Ltd. (72) Inventor Yuyuki Fujiwara 1-5 Wakihamacho, Chuo-ku, Kobe-shi, Hyogo Prefecture No. 8 Kobelco Research Institute Co., Ltd. (56) Reference JP-A-9-53141 (JP, A) JP-A-8-225891 (JP, A) JP-A-2001-49335 (JP, A) Open 2000-282101 (JP, A) (58 ) investigated the field (Int.Cl. 7, DB name) C21D 8/10 B22F 3/24 C22C 33 / 02,38 / 00 - 38/60
Claims (2)
%およびY 2 O 3 :0.15〜0.35%を含む酸化物分散強化
型フェライト系鉄合金管の製造方法であって、金属粉末
と酸化物粉末との混合焼結により素材を作製し、合計3
回以上の冷間圧延および焼鈍を繰返して所要形状の管に
する際に、各冷間圧延の圧延率は30%以上、圧延途中の
焼鈍は1100℃未満、最終の焼鈍は1100℃以上でおこなう
ことを特徴とする、クロムを含む酸化物分散強化型フェ
ライト系鉄合金管の製造方法。1. Cr: 11-15%, Ti: 0.1-1 by mass%
% And Y 2 O 3 : 0.15 to 0.35% containing oxide dispersion strengthening
A method for manufacturing a type ferritic iron alloy tube, wherein a raw material is prepared by mixing and sintering metal powder and oxide powder, and a total of 3
When cold rolling and annealing are repeated more than once to form a tube with the required shape, the rolling ratio of each cold rolling is 30% or more, the annealing during rolling is less than 1100 ° C, and the final annealing is performed at 1100 ° C or more. A method for producing an oxide dispersion strengthened ferritic iron alloy tube containing chromium.
%、WおよびMoの1種または2種の合計:0.1〜4%、
ならびにY 2 O 3 :0.15〜0.35%を含む酸化物分散強化
型フェライト系鉄合金管の製造方法であって、金属粉末
と酸化物粉末との混合焼結により素材を作製し、合計3
回以上の冷間圧延および焼鈍を繰返して所要形状の管に
する際に、各冷間圧延の圧延率は30%以上、圧延途中の
焼鈍は1100℃未満、最終の焼鈍は1100℃以上でおこなう
ことを特徴とする、クロムを含む酸化物分散強化型フェ
ライト系鉄合金管の製造方法。2. Cr: 11-15%, Ti: 0.1-1 in mass%
%, The total of one or two of W and Mo: 0.1 to 4%,
And Y 2 O 3: ODS containing 0.15 to 0.35%
A method for manufacturing a type ferritic iron alloy tube, wherein a raw material is prepared by mixing and sintering metal powder and oxide powder, and a total of 3
When cold rolling and annealing are repeated more than once to form a tube with the required shape, the rolling ratio of each cold rolling is 30% or more, the annealing during rolling is less than 1100 ° C, and the final annealing is performed at 1100 ° C or more. A method for producing an oxide dispersion strengthened ferritic iron alloy tube containing chromium.
Priority Applications (3)
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---|---|---|---|
JP2001062913A JP3462182B2 (en) | 2001-03-07 | 2001-03-07 | Method for producing chromium-containing oxide dispersion strengthened ferritic iron alloy tube |
FR0202781A FR2821858B1 (en) | 2001-03-07 | 2002-03-05 | PROCESS FOR THE PRODUCTION OF A CONSOLIDATED FERRITIC FERROLING SHEATH WITH OXIDE DISPERSION AND CONTAINING CHROMIUM |
CNB021068550A CN1159471C (en) | 2001-03-07 | 2002-03-06 | Method for producing oxide dispersion enhanced Cr-contg. ferrie Fe-alloy pipe |
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Application Number | Priority Date | Filing Date | Title |
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JP2001062913A JP3462182B2 (en) | 2001-03-07 | 2001-03-07 | Method for producing chromium-containing oxide dispersion strengthened ferritic iron alloy tube |
Publications (2)
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JP2002266026A JP2002266026A (en) | 2002-09-18 |
JP3462182B2 true JP3462182B2 (en) | 2003-11-05 |
Family
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JP2001062913A Expired - Fee Related JP3462182B2 (en) | 2001-03-07 | 2001-03-07 | Method for producing chromium-containing oxide dispersion strengthened ferritic iron alloy tube |
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Country | Link |
---|---|
JP (1) | JP3462182B2 (en) |
CN (1) | CN1159471C (en) |
FR (1) | FR2821858B1 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
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JP3672903B2 (en) | 2002-10-11 | 2005-07-20 | 核燃料サイクル開発機構 | Manufacturing method of oxide dispersion strengthened ferritic steel pipe |
JP5097017B2 (en) * | 2008-06-03 | 2012-12-12 | 住友金属工業株式会社 | Manufacturing method of high Cr ferritic heat resistant steel |
JP5339503B2 (en) * | 2008-09-12 | 2013-11-13 | 国立大学法人京都大学 | Super ODS steel |
KR101182092B1 (en) | 2010-12-27 | 2012-09-19 | 주식회사 포스코 | Ferritic stainless steel with good workability and method of manufacturing the same |
KR101586546B1 (en) * | 2013-03-29 | 2016-01-29 | 한국원자력연구원 | Ferritic oxide dispersion strengthened alloy with enhanced room temperature and high temperature strength and manufacturing method thereof |
KR20150104348A (en) * | 2014-03-05 | 2015-09-15 | 한국원자력연구원 | Ferrite/martensitic oxide dispersion strengthened steel with excellent creep resistance and manufacturing method thereof |
CN106756430B (en) * | 2016-11-24 | 2018-07-06 | 天津大学 | A kind of method that low-temperature in-site prepares nano magnalium spinelle enhancing ferrous alloy |
CN114134429A (en) * | 2021-12-03 | 2022-03-04 | 中国核动力研究设计院 | ODS ferrite stainless steel fuel cladding tube and preparation method thereof |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US4732622A (en) * | 1985-10-10 | 1988-03-22 | United Kingdom Atomic Energy Authority | Processing of high temperature alloys |
DE19511089A1 (en) * | 1995-03-25 | 1996-09-26 | Plansee Metallwerk | Component with soldered foils made of ODS sintered iron alloys |
-
2001
- 2001-03-07 JP JP2001062913A patent/JP3462182B2/en not_active Expired - Fee Related
-
2002
- 2002-03-05 FR FR0202781A patent/FR2821858B1/en not_active Expired - Fee Related
- 2002-03-06 CN CNB021068550A patent/CN1159471C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JP2002266026A (en) | 2002-09-18 |
CN1386884A (en) | 2002-12-25 |
FR2821858B1 (en) | 2007-10-05 |
FR2821858A1 (en) | 2002-09-13 |
CN1159471C (en) | 2004-07-28 |
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