JPS6256557A - Stainless steel material excellent in neutron-absorption capacity and its production - Google Patents

Abstract

PURPOSE:To develop a stainless steel remarkably excellent in neutron-absorption capacity, having superior hot workability, cold workability and secondary operation properties and further excellent in castability, mechanical properties, corrosion resistance and weldability by adding specific elements excellent in neutron- absorption capacity, such as Gd and the like, to a stainless steel. CONSTITUTION:As a stainless steel having superior neutron-absorption capacity for use in a neuclear reactor and facilities for manufacture, handing, transportation, storage and waste disposal of nuclear fuel, a stainless steel ingot having a composition containing, by weight, 0.1-3.0% Gd, 0.01-0.15% C, <1.5% Si, <2.0% Mn, <0.045% P, <0.03% S, 7-35% Ni, 15-30% Cr, <5% Mo, <1% Ti, <2% Nb and <0.3% N or further containing <0.1% Co is used. The above stainless steel ingot is heated to 1.050-1.150 deg.C and a Gd-rich phase is dispersed finely and uniformly by a single hot or cold working, so that property of secondary operation to products, ductility, toughness and weldability can be improved.

Description

【発明の詳細な説明】 ［発明の利用分野］ 本発明１よ７中性子吸収峻の優れたステンレス鋼材及び
七の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present inventions 1 to 7 relate to stainless steel materials with excellent neutron absorption properties and the method for producing the same.

［発明の背景］ 一般に、原子炉及び原子燃料の製造、取扱い、輸送、貯
蔵、再処理、廃棄物処理の施設において、原子燃料物質
に基本的に要求されるのが未臨界性の確保である。[Background of the Invention] In general, in nuclear reactors and nuclear fuel production, handling, transportation, storage, reprocessing, and waste treatment facilities, the basic requirement for nuclear fuel materials is to ensure subcriticality. .

ところで、２３５−Ｕ、２３９−Ｐｕ’Ｊ（７）核***
性物質は、熱中性子（エネルギー数ｅＶ程度のエネルギ
ーを有する中性子）に対して核***を起し易いため、こ
の熱中性子を吸収することにより熱中性子束を下げて、
未臨界性を高める必要がある。そのため、原子燃料サイ
クル施設の各種構造物には熱中性子吸収能の高い金属材
料が多く使用されている。By the way, 235-U, 239-Pu'J (7) fissile materials tend to undergo nuclear fission in response to thermal neutrons (neutrons with an energy of about the energy number eV), so by absorbing these thermal neutrons, Lower the thermal neutron flux,
It is necessary to improve subcriticality. Therefore, many metal materials with high thermal neutron absorption ability are used in various structures of nuclear fuel cycle facilities.

特に、近年、商業用原子炉において１ｉ、原子燃料の高
燃焼度化に伴なう高濃縮度化が進んでいること、また、
原子燃料サイクル施設のより　密化の要求が高まってい
ることから、上記構造物に対しては、従来よりさらに熱
中性子吸収能の高い材料が要望される。In particular, in recent years, commercial nuclear reactors have become highly enriched due to the increase in the burnup of nuclear fuel, and
Due to the increasing demand for denser nuclear fuel cycle facilities, materials with higher thermal neutron absorption capacity than conventional materials are required for the above structures.

また、上記構造物は、鋼材に各種加工を施して作製され
るため、鋼材には、鋳造性、熱間Ｍｅ　■−性、冷間加
工性、二次加工性１機械的性質、溶接性等に優れている
ことも要求される。また、鋳造性良く製造されることも
必要である。、すらに、核燃料、廃棄物は腐食性を有し
ているので試材ｔ４は耐食性に優れている必要もある。In addition, since the above-mentioned structures are manufactured by subjecting steel materials to various processing, the steel materials include castability, hot metallization properties, cold workability, secondary workability, mechanical properties, weldability, etc. They are also required to be excellent at. Moreover, it is also necessary to be manufactured with good castability. Furthermore, since nuclear fuel and waste are corrosive, the test material t4 must also have excellent corrosion resistance.

ところで、従来、熱中性子吸収能を持つ金属材′ｊ−１
としては、熱中性子吸収能に優れれいるＢを利用したＢ
含有ステン【／ス鋼及びＢ含有鋼が製作されている。By the way, conventionally, metal material ′j-1 with thermal neutron absorption ability
As for B, which utilizes B which has excellent thermal neutron absorption ability,
B-containing stainless steel and B-containing steel are manufactured.

しかし、従来のこの種のステンレス鋼あるいは鋼は、Ｂ
含有量が増加するにつれて加工性が劣化し、熱間鍛造あ
るいは圧延が困難となる。また、機械的性質も劣化する
、 −・方、加工性、機械的性質を確保するためにはＢ含有
量を、炭素鋼の場合では２％以下、ステンレス鋼の場合
ではそれ以下とせざるを得す、そして、かかる材料は実
用されているものの、その含有量が低いので熱中性子吸
収能が低いという問題がある。However, this type of conventional stainless steel or steel is
As the content increases, workability deteriorates and hot forging or rolling becomes difficult. In addition, the mechanical properties also deteriorate.In order to ensure workability and mechanical properties, the B content must be kept below 2% in the case of carbon steel and below that in the case of stainless steel. Although such materials are in practical use, they have a problem of low thermal neutron absorption capacity due to their low content.

従って、熱中性子吸収能に優れ、かつ、加工性、機械的
に１質も良好な鋼材の出現が要望されている。Therefore, there is a demand for a steel material that has excellent thermal neutron absorption ability and also has good workability and mechanical quality.

［発明の目的］ 本発明、熱中性子吸収能が著しく優れ、熱間加工性、冷
間加工性及び二次加工性が良好で構造物の製作が容易で
あり、また、鋳造性良く製造でき、さらに機械的性質、
耐食性、溶接性等性も優れたステンレス鋼材及びその製
造方法を提供するものである。[Objective of the Invention] The present invention has extremely excellent thermal neutron absorption ability, good hot workability, cold workability and secondary workability, easy to manufacture structures, and can be manufactured with good castability. Furthermore, mechanical properties,
The present invention provides a stainless steel material with excellent corrosion resistance, weldability, etc., and a method for manufacturing the same.

［発明のｉ釆Ｊ 本出願に係る第１の発明は、玉噛−％で、Ｇｄ：０．１
〜３．０％を含有し、かつ、ｃ　：　ｏ、ｏｔ〜０．１
５％、Ｓ　ｉ　：　１．５％以下、Ｍｎ＋２．０％以下
、Ｐ：０．０４５％以下、Ｓ　：　０．０３％以下、Ｎ
ｉミニフル３５、Ｃｒ：１５〜３０％、Ｍｏ：５％以下
、Ｔ　ｉ　：　１％以下、Ｎｂ：２％以下、Ｎ　：　０
．３％以下、残部Ｆｅ及び不可避的不純物からなること
を特徴とする中性子吸収能の優れたステンレス鋼材であ
る。[I-button J of the invention The first invention according to the present application is Tamagami-%, Gd: 0.1
~3.0%, and c: o, ot ~0.1
5%, Si: 1.5% or less, Mn+2.0% or less, P: 0.045% or less, S: 0.03% or less, N
i Mini Full 35, Cr: 15-30%, Mo: 5% or less, Ti: 1% or less, Nb: 2% or less, N: 0
．． It is a stainless steel material with excellent neutron absorption ability, characterized by comprising 3% or less, the balance being Fe and unavoidable impurities.

第１発明における成分限定理由を示す。The reason for limiting the ingredients in the first invention will be shown.

Ｇ　ｄ　：　０．１〜３．０％ 従来は中性子吸収能を向上させるためにＢが使用されて
いるが、Ｇｄは中性子吸収断面積が大きく、理論的には
、Ｂの約４倍の中性子吸収断面積を有する。従って、Ｇ
ｄは優れた熱中性子吸収能を付与するために不可欠な元
素である。ただ、舎右量が０．１％未満ではその効果が
少なく、また。G d : 0.1 to 3.0% Conventionally, B is used to improve neutron absorption ability, but Gd has a large neutron absorption cross section and theoretically has a neutron absorption capacity of about 4 times that of B. It has an absorption cross section. Therefore, G
d is an essential element for imparting excellent thermal neutron absorption ability. However, if the amount is less than 0.1%, the effect will be small.

３％を越えると熱間加工、冷間加工、二次加工の成形加
工性が悪くなり、また、材料特性のうち、特に延性　靭
性、溶接性が劣るようになる。If it exceeds 3%, formability in hot working, cold working, and secondary working will deteriorate, and among material properties, particularly ductility, toughness, and weldability will deteriorate.

ｅ　　：　　０．０ｌ−ｏ−＋ｓ％ Ｃは、構造材料として強度確保のため、０．０１％以−
ヒ必［１＝あるが、あまり多くするとＣｒ７ｆ化物が粒
界に析出し耐食性の劣化を招くので上限は０．１５％と
する。e: 0.0l-o-+s% C is 0.01% or more to ensure strength as a structural material.
It is necessary [1 = Yes, but if the content is too large, Cr7f oxides will precipitate at grain boundaries, leading to deterioration of corrosion resistance, so the upper limit is set to 0.15%.

Ｓ　ｉ　：　１．５％以下 Ｓｉは脱酸剤として加えられるが、多くすると加工性、
溶接性を阻害するので上限を１．５％とする。Si: 1.5% or less Si is added as a deoxidizing agent, but if it increases, it improves processability,
Since it impedes weldability, the upper limit is set at 1.5%.

Ｍｎ：２．０％以下 Ｍｎは、脱酸剤として、また、熱加工性改善のため加え
られるが、２．０％以り添加してもその効果は飽和する
ので上限は２．０％とする。Mn: 2.0% or less Mn is added as a deoxidizing agent and to improve heat processability, but its effect is saturated even if it is added above 2.0%, so the upper limit is 2.0%. do.

Ｐ　：　０．０４５％以下、Ｓ　：　０．０３％以下Ｐ
及びＳは不可避的不純物であるが、多くなると脆化、溶
接性劣化を起すためＰ　：　０．０４５％以Ｆ、　Ｓ　
：　０．０３％以下とする。P: 0.045% or less, S: 0.03% or less P
and S are unavoidable impurities, but in large amounts they cause embrittlement and deterioration of weldability, so P: 0.045% or more F, S
: 0.03% or less.

Ｎｉニア　〜３５％、Ｃｒ：１５〜３０％Ｎｉ　、Ｃｒ
は、オーステナイト組織を得るため、また、耐酸化性の
向トのためにＮｉニア％以下１、Ｃｒ：１５％以上必要
であるが、Ｎｉ：３５％、Ｃｒ　：　３０％を越えると
加工性、溶接性が劣化し、また、経済性も不利になるた
め、Ｎｉミニフル３５、Ｃｒ：１５〜３０％とする。Ni near ~35%, Cr:15~30%Ni, Cr
In order to obtain an austenitic structure and to improve oxidation resistance, it is necessary to have Ni ni% of 1% or less and Cr: 15% or more, but if Ni: 35% or Cr: 30% or more, the workability deteriorates. Since weldability deteriorates and economical efficiency becomes disadvantageous, Ni Miniful 35 and Cr: 15 to 30% are used.

Ｍｏ：５％以下 Ｍｏは、強度、耐食性改善に有効であるが、多く加えて
も効果は飽和し、Ｍｏは高価であるため上限は５％とす
る。Mo: 5% or less Mo is effective in improving strength and corrosion resistance, but the effect is saturated even if added in large amounts, and Mo is expensive, so the upper limit is set at 5%.

Ｔ　ｉ　：　１％以下、Ｎｂ：２％以ＦＴｉ、Ｎｂは強
力な炭化物生成元素であり、これらの添加によってＣｒ
炭化物の粒界析出が抑制され、耐食性が向−ヒするが、
本発明で限定したＣ量においては、Ｔ　ｉ　：　１％以
下、Ｎｂ：２％以下で耐食性の向上には十分であるため
この範囲とする。Ti: 1% or less, Nb: 2% or more FTi and Nb are strong carbide-forming elements, and their addition reduces Cr.
Grain boundary precipitation of carbides is suppressed and corrosion resistance is improved, but
In the C content limited in the present invention, Ti: 1% or less and Nb: 2% or less are sufficient to improve corrosion resistance, so these ranges are set.

Ｎ　：　０．３％以下 Ｎは、Ｃと同じ作用により強度の向上に有効であるが、
多く加えるとＣｒ窒化物の形成により耐食性を劣化させ
るので、上限は０．３％とする。N: 0.3% or less N is effective in improving strength due to the same effect as C, but
If too much is added, corrosion resistance will deteriorate due to the formation of Cr nitrides, so the upper limit is set to 0.3%.

なお、本出願に係る鋼材はフェライト系ステンレス鋼材
である。Note that the steel material according to the present application is a ferritic stainless steel material.

本出願に係る第２の発明は、屯凌％ｃ、Ｇｄ二０４１〜
３．０％を含有し、かつ、Ｃ：　０．０１〜０．２０％
、Ｓ　ｉ　：　１．５％以下、Ｍｎ：１．５％以下、Ｐ
：０．０４５％以下、　Ｓ　：　０．０３％以下、Ｎｉ
。６％以下、　　Ｃｒ　：　１Ｉ＝３２％、Ｍ　ｏ　＋
　３％以下、残部Ｆｅ及び不可避的不純物からなること
を特徴とする中性子吸収能の優れたステンレス鋼材であ
る。The second invention according to the present application is Tunling%c, Gd2041~
Contains 3.0%, and C: 0.01-0.20%
, S i: 1.5% or less, Mn: 1.5% or less, P
: 0.045% or less, S: 0.03% or less, Ni
. 6% or less, Cr: 1I=32%, M o +
It is a stainless steel material with excellent neutron absorption ability, characterized by comprising 3% or less, the balance being Fe and unavoidable impurities.

以下に成分限定理由を説明する。The reasons for limiting the ingredients will be explained below.

Ｇｄ、Ｓｉ、Ｐ、Ｓ、については第１発明と同様の理由
による。Regarding Gd, Si, P, and S, the reasons are similar to those of the first invention.

Ｃ：　０．０１〜０．２０％ Ｃは。強度確保のため０．０１以−Ｆ必要であるが、多
く加えるとフェライト系、フェライト・オーステナイト
２層系ステンレス鋼では効果を起し、二次加工性、溶接
性が劣化するため上限は０．２０％とする。C: 0.01-0.20% C. 0.01 or more -F is necessary to ensure strength, but if too much is added, it will have an effect on ferritic and ferritic-austenite two-layer stainless steels, and secondary workability and weldability will deteriorate, so the upper limit is 0.01. It shall be 20%.

Ｍｎ：１．５％以Ｆ Ｍｎは脱酸に、また、熱加工性改善 あるが、フェライト系鋼では、１．５％を越えて添加し
ても効果は飽和するめ上限は１５％とする。Mn: 1.5% or more F Mn is effective in deoxidizing and improves heat workability, but in ferritic steel, the effect is saturated even if it is added in excess of 1.5%, so the upper limit is set at 15%.

Ｎｉ：６％以下 Ｎｉはフェライト系ステンレス鋼においては靭性の改善
に有効であるために、また、２相系ステンレス鋼・にお
いて１オＣｒ当量に応じてオーステナイト層を導入する
ために添加する。ｌ−７かｌ−、、，６％を越えて添加
してもその効果は飽和するのでト限を６％とする。Ni: 6% or less Ni is added to ferritic stainless steel because it is effective in improving toughness, and to introduce an austenite layer in duplex stainless steel in accordance with 100 Cr equivalent. Even if it is added in excess of l-7 or l-6%, the effect will be saturated, so the limit is set at 6%.

Ｃｒ：１ｌ−３２％ Ｃｒは耐食性のため１１％以り必要であるが、あまり多
く加えすぎると加工性、溶接性を劣化さ（）るため１１
〜３２％の範囲とする。Cr: 1l-32% Cr is necessary at least 11% for corrosion resistance, but adding too much will deteriorate workability and weldability.
The range is 32%.

Ｍ　ｏ　：　３％以下 Ｍｏは、強度、耐食性改善に有効であるが、？−〈加え
ても効果は飽和すること、また、経済的にイ；利である
ことがら上限は３％とする。Mo: 3% or less Mo is effective in improving strength and corrosion resistance, but is it? - The upper limit is set at 3% because the effect will be saturated even if it is added, and it is economically advantageous.

なお、第１発明と第２発明において、Ｇｏを０．１％以
下添加すると中性子吸収能がより一層向−ヒする。従っ
て、第１発明又は第２発明に係るステンレス鋼を、制御
棒用構成材料のように、特に原子炉内で使用する場合に
は、誘導放射能による被曝を低減することが可能となる
。In addition, in the first invention and the second invention, when Go is added in an amount of 0.1% or less, the neutron absorption ability is further decreased. Therefore, when the stainless steel according to the first or second invention is used as a constituent material for control rods, particularly in a nuclear reactor, it is possible to reduce exposure to induced radioactivity.

また、Ｓｉの上限を０．１％とした場合には加工性がよ
り一層向上し、形状が複雑な構造物、あるいは高度の加
工性が要求されるような構造物に加工する、−１とも可
能となる。このようにＳｉを０．１％如何：こすると加
工性が向［−するのは次の理由に、ン、るゆすなわち、
Ｇｄは鋼中にほとんど溶解せずＧｄ富化相と１．て分散
し、この相にはＳｉが濃化する６従・）で、Ｓｉを０．
１％以下にすると、Ｇｄ富化相は硬化を起さず、Ｇｄ富
化相の硬化による゛加工性の劣化を阻止するこ とができるためである。In addition, when the upper limit of Si is set to 0.1%, the workability is further improved, and it can be processed into structures with complex shapes or structures that require a high degree of workability. It becomes possible. In this way, when Si is added at 0.1%, the workability is improved by rubbing.The reason for this is as follows:
Gd hardly dissolves in steel and forms a Gd-enriched phase.1. Si is dispersed in this phase, and Si is concentrated in this phase.
This is because when the amount is 1% or less, the Gd-enriched phase does not harden, and deterioration of workability due to hardening of the Gd-enriched phase can be prevented.

なお、本出願に係るステンレス鋼材はフェライト系、あ
るいはフェライト・オーステナイトの２相系スデ゛／１
／ス鋼材であり、これにより耐食性が確保される。The stainless steel material according to the present application is a ferritic or ferritic-austenite two-phase stainless steel material.
/ steel material, which ensures corrosion resistance.

本出願に係る第３発明は、玉量％で、Ｇｄ：０．１〜３
．０％を含有し、かつ、Ｃ・０．０１〜０．１５％、　
Ｓｉ：１．５％以下、Ｍｎ＋２．０％以下、Ｐ　：　０
．０４５％以下、Ｓ　：　０．０３％以下、Ｎｉニア　
〜３５％、Ｃｒ：１５〜３０％、　Ｍ　ｏ　：　５％以
下、Ｔｉ：１％以下、　Ｎｂ：２％以下、Ｎ　：　０．
３％以下、残部Ｆｅ及び不可避的不純物からなるステ〉
ルス鋼を溶製して鋳塊を作製し、該鋳塊を１０５０℃〜
１１５０℃において加熱処理し、次いで該鋳塊を少なく
とも１回熱回加下又は冷間加工することを特徴とする中
性子吸収能の優れたステンレス鋼材の製造方法である。The third invention according to the present application is ball amount %, Gd: 0.1 to 3
．． Contains 0%, and C 0.01 to 0.15%,
Si: 1.5% or less, Mn+2.0% or less, P: 0
．． 045% or less, S: 0.03% or less, Ni near
~35%, Cr: 15-30%, Mo: 5% or less, Ti: 1% or less, Nb: 2% or less, N: 0.
3% or less, the balance consisting of Fe and unavoidable impurities>
Ruth steel is melted to produce an ingot, and the ingot is heated to 1050℃~
This is a method for producing a stainless steel material with excellent neutron absorption ability, which is characterized by heat treating at 1150° C. and then subjecting the ingot to thermal processing or cold working at least once.

本出願に係る第４発明は、重量％で、Ｇｄ：０．１〜３
．０％を含有し、かつ、ｃ　：　ｏ、ｏｉ〜０．２０％
、　５ｉ＝１．５％以下、Ｍｎ：１．５％以下、Ｐ　：
　０．０４５％以下、Ｓ：０．０３％以下、Ｎｉ：６％
以下、Ｃｒ：１１〜３２％、　Ｍ　ｏ　：　３％以下、
残部Ｆｅ及び不可避的不純物からなるステンレス鋼を溶
製して鋳塊を作製し、該鋳塊を１０５０℃〜１１５０℃
において加熱処理し、次いで該鋳塊を少なくとも１回熱
間加工又は冷間加工することを特徴とする中性イ吸収能
の優れたステンレス鋼材の製造方法である。The fourth invention according to the present application has Gd: 0.1 to 3 in weight%.
．． Contains 0%, and c: o, oi ~ 0.20%
, 5i=1.5% or less, Mn: 1.5% or less, P:
0.045% or less, S: 0.03% or less, Ni: 6%
Below, Cr: 11 to 32%, Mo: 3% or less,
An ingot is produced by melting stainless steel consisting of the remainder Fe and unavoidable impurities, and the ingot is heated at 1050°C to 1150°C.
This is a method for producing a stainless steel material with excellent neutral I absorption ability, which is characterized in that the ingot is heat-treated at a step of 1, and then the ingot is hot-worked or cold-worked at least once.

第３発明及び第４発明における成分限定理由は第１発明
及び第２発明において説明した通りである。The reason for limiting the ingredients in the third invention and the fourth invention is as explained in the first invention and the second invention.

鋳塊を１０５０℃〜１１５０℃に加熱処理する理由を述
べる。The reason why the ingot is heat treated at 1050°C to 1150°C will be described.

Ｇｄは、鋼中に溶解度をほとんど持たないため、鋳塊の
凝固時にはデンドライト間にＧｄ富化相として析出する
。鋳造のままでは、Ｇｄ富化相が網目状となり、かつ形
状も複雑となるため、熱間加工時にはこの部分に割れが
発生し易い。しかるに、鋳造後の鋳塊を１０５０℃〜ｌ
ｌ５０℃に加熱すると、Ｇｄ富化相は球状化、均−分布
化するので熱間加工時における割れの発生を防出するこ
とができるためである。Since Gd has almost no solubility in steel, it precipitates as a Gd-enriched phase between dendrites when an ingot solidifies. If as cast, the Gd-enriched phase becomes network-like and has a complicated shape, so cracks are likely to occur in this part during hot working. However, after casting, the ingot is heated to 1050℃~l
This is because when heated to 150° C., the Gd-enriched phase becomes spherical and uniformly distributed, making it possible to prevent cracking during hot working.

また、鋳塊を少なくとも１回熱間加に又は冷間加工する
のは、かかる熱間油−Ｔ−又は冷間加工を施すとＧｄ富
化相は均一微細に分散し、製品へのゴー次加工性、延性
、靭性、溶接性が改善されるからである。In addition, the reason why the ingot is hot-worked or cold-worked at least once is that when such hot oil-T- or cold working is performed, the Gd-enriched phase is uniformly and finely dispersed, which improves the quality of the product. This is because workability, ductility, toughness, and weldability are improved.

［実施例］ 第１表に示す成分の鋳塊を１０ｋｇ溶製した。[Example] 10 kg of ingots having the components shown in Table 1 were melted.

Ｎｏｔ〜Ｎｏ５は第２発明の実施例であり、Ｎｏ７〜Ｎ
ｏ１２は第１発明の実施例である。Not to No. 5 are examples of the second invention, and No. 7 to N
o12 is an embodiment of the first invention.

Ｎｏｔ〜Ｎｏ４はフェライト系（マルテンサイト組織及
び混合ｍｓを含む）ステンレス鋼、Ｎ。Not to No. 4 are ferritic (including martensitic structure and mixed ms) stainless steel, N.

５〜Ｎｏ６はオーステナイト・フェライト２相ステンレ
ス鋼、Ｎｏ７〜Ｎｏ１５はオーステナイト系ステンレス
鋼である。No. 5 to No. 6 are austenitic-ferritic dual-phase stainless steels, and No. 7 to No. 15 are austenitic stainless steels.

Ｎｏｌ〜Ｎｏ８には、従来材料である。Ｂを約２％添加
１．た鋼の熱中性子吸収能を十分ＦまわるＧｄを添加し
たものである。No. 1 to No. 8 are conventional materials. Add approximately 2% of B1. This steel contains enough Gd to exceed the thermal neutron absorption capacity of steel.

Ｎｏ９〜Ｎｏ１５は、Ｇｄ敏の実用上有効な範囲を決め
るため、１８−８オーステナイト系ステンレス鋼につい
てＧｄｉをを系統的に変化させた比較例である。No. 9 to No. 15 are comparative examples in which Gdi was systematically changed for 18-8 austenitic stainless steel in order to determine a practically effective range of Gd density.

Ｎｏ９〜Ｎｏ１５の鋳塊の硬さに及ぼすＧｄｉの影響を
第１図に示す、Ｇｄ量が増すにつれて、デンドライト凝
固相聞に析出するＧｄ富化相が増加するため硬さは」二
昇する。Ｇｄｉが約３．５％以りでは硬さがＨｖ２００
以にとなり、加工性が劣化することが予想される。The influence of Gdi on the hardness of No. 9 to No. 15 ingots is shown in FIG. 1. As the amount of Gd increases, the Gd-enriched phase precipitated in the dendrite solidification phase increases, so the hardness increases. When Gdi is about 3.5% or more, the hardness is Hv200.
As a result, it is expected that workability will deteriorate.

Ｇｄ富化相をＥＰＭＡにより分析したところ、Ｇｃｌ富
化相はＧｄと、鋼のＦ：、要構成元素であるＦｅ、Ｃｒ
、Ｎｉ等の金属間化合物相と判断された。When the Gd-enriched phase was analyzed by EPMA, it was found that the Gcl-enriched phase contains Gd, F of steel, Fe, and Cr, which are essential constituent elements.
, Ni, etc., was determined to be an intermetallic compound phase.

またＧｄ富化相には複数の種類があり、いずれも５３が
濃化されており、５ｉｌ（低減はＧｄ富化相の低減並び
に硬さの低量に有効であることがわかる。Ｎｏ１ｌはＮ
ｏ１２１て吋しＳｉ験を低減させたものであるが、その
硬さは、Ｎｏ１２よりＨｖ２０程度低くなり、後述する
第２表の評価結束で示すごとく、熱間加工性、冷間加工
性及び溶接性の改善に有効であることがわかった。In addition, there are multiple types of Gd-enriched phases, all of which are enriched with 53, and it can be seen that 5il (reduction) is effective in reducing the Gd-enriched phase and reducing the amount of hardness.
No. 121 has a lower Si test, but its hardness is about 20 Hv lower than No. 12, and as shown in the evaluation results in Table 2 below, it has poor hot workability, cold workability, and weldability. It was found to be effective in improving sexual performance.

第２図に、鋳塊の溶製から板、棒、管等の製品に至る製
造り稈の概略を示す。Figure 2 shows an outline of the production process from ingot melting to products such as plates, rods, and pipes.

通常のＬ程１に対して、本例に係る工程２マは、鋳塊に
Ｇｄ富化相を球状化、均一・分布化するための熱処理を
入れ、また、冷間加工１程を１回置］二施している。In contrast to the usual L step 1, in step 2 of this example, the ingot is heat treated to make the Gd-enriched phase spheroidal, uniform and distributed, and cold worked once in step 1. ] He gave two alms.

１］程ｌでは、第３図に示すごとく、Ｇｄ富化相が網目
状に分布するのに対（７，１程？ではこれが球状化し、
かつ、均−ｌ！！ｋｍに分散することがわかる。1] As shown in Figure 3, the Gd-enriched phase is distributed in a network shape (at around 7.1?), it becomes spheroidal,
And uniformly! ! It can be seen that it is distributed over km.

Ｎｏ７〜Ｎｏ１２の供試材について、鋳塊の健全性、熱
間加工性、冷間加工性を評価し、さらに厚さ３ｍｍの板
材を製作し１機械的性質（４度と延性）、耐食性（水浸
漬１力月）、溶接性（Ｇｄを含まない共金系溶接材料を
用い、斜めｙ形溶接割れ試験）及び熱中性子吸収能を評
価１１．た。The soundness, hot workability, and cold workability of the ingots were evaluated for the test materials No. 7 to No. 12, and plates with a thickness of 3 mm were manufactured to evaluate the mechanical properties (ductility of 4 degrees) and corrosion resistance (1). Evaluation of weldability (diagonal Y-shaped weld cracking test using co-metallic welding material that does not contain Gd) and thermal neutron absorption capacity11. Ta.

評価結果を第２表に示す。The evaluation results are shown in Table 2.

Ｇｄｉを系統的に変化させたＮｏ９〜Ｎｏ１５の鋼にお
いて、Ｇｄ　Ｊｄ約８％以上では、鋳塊と部に割れが発
生すること、また、熱間加工性が著しく劣るため、実用
不可と判断された。In No. 9 to No. 15 steels in which Gdi is systematically varied, if Gd Jd is about 8% or more, cracks will occur in the ingot and parts, and hot workability will be extremely poor, so it is judged to be impractical. Ta.

Ｇｄｌ約４．５％以」−では、加工性がやや劣り、特に
溶接性が著しく劣るため、これも実用上不可と判断され
た。これらの加工性、溶接性は、先に示したＳｉ量の低
減により改善が期待できるが。If the Gdl is about 4.5% or more, the workability is slightly inferior, and in particular the weldability is significantly inferior, so this was also judged to be practically impossible. These workability and weldability can be expected to be improved by reducing the amount of Si as described above.

実用上の安全を見込み、ＧｄｌのＬ限は３％とした。Considering practical safety, the L limit of Gdl was set at 3%.

従って１本実施例に係るＮｏ１−Ｎｏ１２のステンレス
鋼は、熱中性子吸収能に優れ、加り性、機械的性質、耐
食性、溶接性も構造材料と１．て実用Ｉ：問題のない特
性を有していることがわかる。Therefore, the stainless steels No. 1 to No. 12 according to this example have excellent thermal neutron absorption ability, and have the same additive properties, mechanical properties, corrosion resistance, and weldability as structural materials. Practical I: It can be seen that it has characteristics without problems.

［発明の効果］ 以−ヒ、本出願に係る第１５１明及び第２発明は、熱中
性ｆ吸収能が茗しく優れ、熱間加を性、冷間加工性及び
■二次加工性が良好で構造物の製作が容易であり、＃ｌ
Ｉ造性良く製造でき、ざらに機械的性質、耐食性、溶接
性等性も優れている。従って、原子燃料サイクル施設用
構造材として使用することができ、未臨界性の確保ひい
ては安全性の確保に貢献することができる。[Effects of the Invention] Hereinafter, the 151st invention and the 2nd invention according to the present application have excellent thermal neutral f absorption ability, good hot workability, cold workability, and ■ secondary workability. It is easy to manufacture structures with #l
It can be easily manufactured and has excellent mechanical properties, corrosion resistance, weldability, etc. Therefore, it can be used as a structural material for nuclear fuel cycle facilities, and can contribute to ensuring subcriticality and safety.

また１本出願に係る第３発明及び第４発明は、第１発明
及び第２発明に係る温材を９Ｊ造することができる。ま
た、該鋼材を、割れを発生させることなく加工できるの
で製造歩留を向１−させることができる。Moreover, the third invention and the fourth invention according to the present application can produce 9J of the hot material according to the first invention and the second invention. Further, since the steel material can be processed without causing cracks, the manufacturing yield can be improved.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は、Ｇｄ含有績と硬さとの関係を示すグラフであ
る。第２図は、鋳塊の溶製から板材等の製品材料への製
造過程を示す工程図である。第３図はＧｄ富化相の組織
を示すＷａ微鏡写真である。 第１図 Ｇｄ信唱４　（Ｗｔ、％） 第２図 （工煙１）　　　　　　　（二塚２） 第３図FIG. 1 is a graph showing the relationship between Gd content and hardness. FIG. 2 is a process diagram showing the manufacturing process from ingot melting to product materials such as plates. FIG. 3 is a Wa microscopic photograph showing the structure of the Gd-enriched phase. Figure 1 Gd belief 4 (Wt, %) Figure 2 (Industrial smoke 1) (Futatsuka 2) Figure 3

Claims (1)

【特許請求の範囲】 １　重量％で、Ｇｄ：０．１〜３．０％を含有し、かつ
、Ｃ：０．０１〜０．１５％、Ｓｉ：１．５％以下、Ｍ
ｎ：２．０％以下、Ｐ：０．０４５％以下、Ｓ：０．０
３％以下、Ｎｉ：７〜３５％、Ｃｒ：１５〜３０％、Ｍ
ｏ：５％以下、Ｔｉ：１％以下、Ｎｂ：２％以下、Ｎ：
０．３％以下、残部Ｆｅ及び不可避的不純物からなるこ
とを特徴とする中性子吸収能の優れたステンレス鋼材。 ２　重量％で、Ｇｄ：０．１〜３．０％を含有し、かつ
、Ｃ：０．０１〜０．２０％、Ｓｉ：１．５％以下、Ｍ
ｎ：１．５％以下、Ｐ：０．０４５％以下、Ｓ：０．０
３％以下、Ｎｉ：６％以下、Ｃｒ：１１〜３２％、Ｍｏ
：３％以下、残部Ｆｅ及び不可避的不純物からなること
を特徴とする中性子吸収能の優れたステンレス鋼材。 ３　重量％で、Ｃｏ：０．１％以下を含有する特許請求
の範囲第１項記載の中性子吸収能の優れたステンレス鋼
材。 ４　重量％で、Ｃｏ：０．１％以下を含有する特許請求
の範囲第２項記載の中性子吸収能の優れたステンレス鋼
。 ５　重量％で、Ｓｉ：０．１％以下とした特許請求の範
囲第１項又は第３項記載の中性子吸収能の優れたステン
レス鋼材。 ６　重量％で、Ｓｉ：０．１％以下とした特許請求の範
囲第２項又は第４項記載の中性子吸収能の優れたステン
レス鋼材。 ７　重量％で、Ｇｄ：０．１〜３．０％を含有し、かつ
、Ｃ：０．０１〜０．１５％、Ｓｉ：１．５％以下、Ｍ
ｎ：２．０％以下、Ｐ：０．０４５％以下、Ｓ：０．０
３％以下、Ｎｉ：７〜３５％、Ｃｒ：１５〜３０％、Ｍ
ｏ：５％以下、Ｔｉ：１％以下、Ｎｂ：２％以下、Ｎ：
０．３％以下、残部Ｆｅ及び不可避的不純物からなるス
テンレス鋼を溶製して鋳塊を作製し、該鋳塊を１０５０
℃〜１１５０℃において加熱処理し、次いで該鋳塊を少
なくとも１回熱間加工又は冷間加工するュとを特徴とす
る中性子吸収能の優れたステンレス鋼材の製造方法。 ８　重量％で、Ｇｄ：０．１〜３．０％を含有し、かつ
、Ｃ：０．０１〜０．２０％、Ｓｉ：１．５％以下、Ｍ
ｎ：１．５％以下、Ｐ：０．０４５％以下、Ｓ：０．０
３％以下、Ｎｉ：６％以下、Ｃｒ：１１〜３２％、Ｍｏ
：３％以下、残部Ｆｅ及び不可避的不純物からなるステ
ンレス鋼を溶製して鋳塊を作製し、該鋳塊を１０５０℃
〜１１５０℃において加熱処理し、次いで該鋳塊を少な
くとも１回熱間加工又は冷間加工することを特徴とする
中性子吸収能の優れたステンレス鋼材の製造方法。 ９　重量％で、Ｃｏ：０．１％以下を含有する特許請求
の範囲第７項記載の中性子吸収能の優れたステンレス鋼
材の製造方法。 １０　重量％で、Ｃｏ：０．１％以下を含有する特許請
求の範囲第８項記載の中性子吸収能の優れたステンレス
鋼材の製造方法。 １１　重量％で、Ｓｉ：０．１％以下とした特許請求の
範囲第７項又は第９項記載の中性子吸収能の優れたステ
ンレス鋼材の製造方法。 １２　重量％で、Ｓｉ：０．１％以下とした特許請求の
範囲第８項又は第１０項記載の中性子吸収能の優れたス
テンレス鋼材の製造方法。[Claims] 1% by weight, containing Gd: 0.1-3.0%, C: 0.01-0.15%, Si: 1.5% or less, M
n: 2.0% or less, P: 0.045% or less, S: 0.0
3% or less, Ni: 7-35%, Cr: 15-30%, M
o: 5% or less, Ti: 1% or less, Nb: 2% or less, N:
A stainless steel material with excellent neutron absorption ability, characterized by comprising 0.3% or less, the balance being Fe and unavoidable impurities. 2% by weight, containing Gd: 0.1-3.0%, C: 0.01-0.20%, Si: 1.5% or less, M
n: 1.5% or less, P: 0.045% or less, S: 0.0
3% or less, Ni: 6% or less, Cr: 11-32%, Mo
: A stainless steel material with excellent neutron absorption ability, characterized by comprising 3% or less, the balance being Fe and unavoidable impurities. 3. The stainless steel material having excellent neutron absorption ability according to claim 1, containing 0.1% or less of Co by weight. 4% by weight, and the stainless steel having excellent neutron absorption ability according to claim 2, containing 0.1% or less of Co. 5% by weight and Si: 0.1% or less, the stainless steel material having excellent neutron absorption ability according to claim 1 or 3. 6% by weight, Si: 0.1% or less, a stainless steel material having excellent neutron absorption ability according to claim 2 or 4. 7% by weight, containing Gd: 0.1 to 3.0%, C: 0.01 to 0.15%, Si: 1.5% or less, M
n: 2.0% or less, P: 0.045% or less, S: 0.0
3% or less, Ni: 7-35%, Cr: 15-30%, M
o: 5% or less, Ti: 1% or less, Nb: 2% or less, N:
An ingot is produced by melting stainless steel consisting of 0.3% or less, the balance being Fe and unavoidable impurities, and the ingot is heated to 1050
1. A method for producing a stainless steel material having excellent neutron absorption ability, which comprises heat treating the ingot at a temperature of 1150 DEG C. to 1150 DEG C., and then hot working or cold working the ingot at least once. 8% by weight, containing Gd: 0.1-3.0%, C: 0.01-0.20%, Si: 1.5% or less, M
n: 1.5% or less, P: 0.045% or less, S: 0.0
3% or less, Ni: 6% or less, Cr: 11-32%, Mo
: An ingot is produced by melting stainless steel consisting of 3% or less, the balance being Fe and unavoidable impurities, and the ingot is heated at 1050°C.
A method for producing a stainless steel material with excellent neutron absorption ability, which comprises heat-treating the ingot at a temperature of ~1150°C, and then subjecting the ingot to hot working or cold working at least once. 9. The method for producing a stainless steel material with excellent neutron absorption ability according to claim 7, which contains 0.1% or less of Co by weight. 10. The method for producing a stainless steel material with excellent neutron absorption ability according to claim 8, which contains 0.1% or less of Co by weight. 11. A method for producing a stainless steel material with excellent neutron absorption ability according to claim 7 or 9, wherein the Si content is 0.1% or less by weight. 12. A method for producing a stainless steel material with excellent neutron absorption ability according to claim 8 or claim 10, in which the Si content is 0.1% or less by weight.