JPH0536482B2 - - Google Patents
Info
- Publication number
- JPH0536482B2 JPH0536482B2 JP59045142A JP4514284A JPH0536482B2 JP H0536482 B2 JPH0536482 B2 JP H0536482B2 JP 59045142 A JP59045142 A JP 59045142A JP 4514284 A JP4514284 A JP 4514284A JP H0536482 B2 JPH0536482 B2 JP H0536482B2
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- steel
- rolling
- manufacturing
- superconducting magnet
- 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 - Lifetime
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 93
- 239000010959 steel Substances 0.000 claims description 93
- 238000004519 manufacturing process Methods 0.000 claims description 37
- 230000004927 fusion Effects 0.000 claims description 29
- 238000000034 method Methods 0.000 claims description 22
- 238000010438 heat treatment Methods 0.000 claims description 18
- 239000000463 material Substances 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 11
- 229910052734 helium Inorganic materials 0.000 claims description 6
- 239000001307 helium Substances 0.000 claims description 6
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 238000005242 forging Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 229910001220 stainless steel Inorganic materials 0.000 claims description 3
- 238000005098 hot rolling Methods 0.000 claims description 2
- 239000010935 stainless steel Substances 0.000 claims description 2
- 238000005096 rolling process Methods 0.000 description 39
- 230000007423 decrease Effects 0.000 description 10
- 230000000694 effects Effects 0.000 description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005336 cracking Methods 0.000 description 7
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- 230000000087 stabilizing effect Effects 0.000 description 5
- 239000002344 surface layer Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000009864 tensile test Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000002788 crimping Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment 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
- Y02E30/10—Nuclear fusion reactors
Description
本発明は非磁性鋼板の製造方法に関し、さらに
詳しくは、4Kで高強度、高靭性を有する核融合
炉超電導マグネツト構造用非磁性鋼板の製造方法
に関する。
核融合炉に不可欠な超電導トロイダルマグネツ
トは、液体ヘリウム温度に冷却され、かつ、強磁
場中で繰返しの高応力が働く苛酷な条件下で稼働
する。従つて、このマグネツトの支持構造用とし
ては液体ヘリウム温度において、高耐力および優
れた破壊靭性を有する非磁性材料が不可欠であ
る。さらに、発錆するとマグネツトの断熱効率を
低下させるので優れた耐銹性をも要求される。
従来、比較的小型の超電導マグネツトの構造材
料としては、SUS304L、SUS304LN等に代表さ
れるオーステナイト系ステンレス鋼が使用されて
いる。しかしながら、これらの材料は優れた耐銹
性、破壊靭性を有するものの耐力が低く、かつ、
オーステナイトの安定性が悪いため、塑性変形に
より容易に透磁率が劣化するという欠点を持つて
いる。
また、高Mn系のオーステナイト鋼、例えば、
18Mn−5Cr鋼、14Mn−2Ni−2Cr鋼等は高耐力
を有し、かつ、高価なNiの含有量が少ないため
経済性に優れているが、破壊靭性が低く、耐銹性
が劣る等の短所を有している。
一方、Ti合金、Ni合金、AI合金等も候補材料
としてあがつているが多量に使用される構造材料
としてはあまりに高価であり、破壊靭性が低いと
いう欠点がある。
従つて、従来におけるこれらの材料は核融合炉
用超電導マグネツトの支持構造材料としては充分
ではない。
本発明は以上説明した超電導マグネツト支持構
造用としての各種材料の欠点および問題点に鑑み
なされたものであつて、液体ヘリウム温度におい
て、耐力1200MPa以上、シヤルピ吸収エネルギ
ー100J以上および破壊靭性値（K1c）150MPa√
ｍ以上を有すると共に優れた耐銹性を兼備し、か
つ、板厚方向の機械的性質のバラツキの小さい大
型超電導マグネツトの支持構造材料として有用な
極低温用の高Mn非磁性鋼板の製造方法を提供す
ることにある。
本発明に係る核融合炉超電導マグネツト構造用
非磁性鋼板の製造方法（以下の説明で単に本発明
に係る非磁性鋼板の製造方法ということがある。）
は、C0.01〜0.10wt％、Si0.01〜1.00wt％、Mn16
〜30wt％、P0.03wt％以下、S0.01wt％以下、
Ni3〜10wt％、Cr12〜20wt％、N0.100〜0.300wt
％を含有し、かつ、wt％Mn×wt％Cr／wt％Ni
≦65、0.200wt％≦Ｃ＋Ｎ≦0.300wt％を満足し、
残部Feおよび不可避不純物からなる鋼塊を1150
〜1250℃に加熱後、鍛造或いは分塊圧延を950℃
以上の温度で終了し、放冷後さらに、その鋼片を
1150〜1250℃に加熱後950〜1010℃の温度で熱間
圧延を終了し、その後800℃以上の温度で１〜60
分間の等温保持或いは空冷後、500℃以下の温度
まで水冷することを特徴とする液体ヘリウム温度
で耐力1200MPa以上、シヤルピ吸収エネルギ
100J以上および破壊靭性値（K1c）150MPa√
以上を有し、かつ、板厚方向の機械的性質のバラ
ツキの小さい核融合炉超電導マグネツトの構造材
料として用いられる極低温用高Mnステンレス系
非磁性鋼板の製造方法である。
本発明に係る核融合炉超電導マグネツト構造用
非磁性鋼板の製造方法について以下詳細に説明す
る。
先ず、本発明に係る非磁性鋼板の製造方法にお
いて使用する鋼の含有成分および成分割合につい
て説明する。
Ｃはオーステナイトの安定化と耐力の向上に有
効な元素であり、含有量が0.01wt％未満ではこの
効果が小さく、また、0.10wt％を越える過剰な含
有量では靭性が低下し、かつ、耐銹性を損なうよ
うになる。よつて、Ｃ含有量は0.01〜0.10wt％と
する。
Siは鋼溶製時の脱酸に必要であり、造塊時に溶
鋼の流動性を高めて鋼塊の内部欠陥を減少させる
と同時に耐力向上にも有効な元素であり、含有量
が0.01wt％未満ではこのような効果がなく、ま
た、1.00wt％を越えて含有されると高温延性の阻
害および靭性の低下をもたらす。よつて、Si含有
量は0.01〜1.00wt％とする。
Mnはオーステナイトの安定化と靭性の向上お
よびＮの固溶限の増大に有効であり、含有量が
16wt％未満ではこの効果が少なく、また、30wt
％を越える過剰な含有はδフエライトが生成し易
く、熱間加工性および靭性が低下する。よつて、
Mn含有量は16〜30wt％とする。
Ｐ、Ｓは共に熱間加工性および靭性を損なう不
純物元素であり、極力低いことが望ましいが、経
済性を考慮してP0.03wt％以下、Ｓは0.01wt％以
下とする。
Niはオーステナイトの安定化と靭性の向上お
よびδフエライトの生成抑制に有効な元素であ
り、含有量が3wt％未満ではこのような優れた効
果は小さく、また、10wt％を越える含有量では
靭性は飽和し、かつ、経済性を損なう。よつて、
Ni含有量は３〜10wt％とする。
Crは耐銹性を付与するために必要であり、か
つ、耐力を向上させる元素であり、含有量が
12wt％未満では耐銹性が充分でなく、また、
20wt％を越える過剰な含有ではδフエライトの
生成を促し、熱間加工性、靭性を低下させる。よ
つて、Ni含有量は12〜20wt％とする。
Ｎはオーステナイトの安定化と耐力の向上に有
効な元素であり、含有量が0.100未満ではこの効
果は小さく、また、0.300wt％を越えて含有され
ると靭性の低下が大きい。よつて、Ｎ含有量は
0.100〜0.300wt％とする。
Ｃ＋Ｎは共に強力にオーステナイトを安定化
し、かつ、耐力、靭性に極めて大きな影響をおよ
ぼす元素であり、Ｃ＋Ｎ含有量が0.200wt％未満
ではオーステナイト安定化および高耐力化の効果
は小さく、また、0.300wt％を越えて含有される
と靭性を著しく低下させる。よつて、Ｃ＋Ｎ含有
量は0.200≦Ｃ＋Ｎ≦0.300wt％とする。
MnおよびCr含有量が増加するとその相剰作用
によりδフエライトの生成が著しくなり、熱間加
工性および靭性を大きく損なう結果となり、ま
た、Niはδフエライトの生成を抑制する効果を
有しており、従つて、δフエライト生成による熱
間加工性および靭性の劣化を防止するためには、
Mn、CrおよびNiの含有量は、wt％Mn×wt％
Cr／wt％Ni≦65にする必要がある。
次に本発明に係る非磁性鋼板の製造方法の製造
条件について説明する。
本発明において核融合炉超電導マグネツト構造
用非磁性鋼板の製造に際しては、熱間加工は２段
階に分けて行う。
即ち、第１段階の熱間加工は鋼塊の鍛造、或い
は、分塊圧延工程であり、第２段階の熱間加工は
第１段階の加工により製造された鋼片の厚板圧延
工程である。また、これらの熱間加工は何れも特
定条件下（加熱温度並びに加工温度範囲の指定）
において実施するものである。
そして、この第１段階における熱間加工の目的
は、鋼塊の粗大な樹枝状組織を破壊し、微細化す
ると共にザク等の欠陥を圧着することにより、鋼
材の内部品質の均質化を図ることにあり、また、
第２段階の熱間加工の目的は、特定の製品形状を
付与すること、および、結晶粒径の調整により目
標とする機械的性質を得ることにある。
なお、このような目的を達成するため、鋼塊か
ら１回の熱間加工工程により厚板圧延を行うこと
も考えられるが、圧延に長時間を必要とし、鋼塊
の温度が著しく低下することになり、後記するよ
うに表面割れ発生の問題を生じるので好ましくな
い。
従つて、本発明に係る核融合炉超電導マグネツ
ト構造用非磁性鋼板の製造方法においては、表面
割れの発生を防止するためにも２段階の熱間加工
を必須の工程として行うものである。
一般に高Mn系のオーステナイト鋼は、炭素
鋼、低合金鋼等に比べ熱間加工性が劣り、適正な
条件で鍛造或いは圧延されないと鋼片、鋼板の表
面に割れが発生して歩留の低下を招く。従つて、
本発明者は、先ず、熱間加工による割れ発生を防
止するため適正な製造条件について研究を行なつ
た。
第１図に、0.07wt％Ｃ−0.27wt％Si−21.38wt
％Mn−0.015wt％Ｐ−0.005wt％Ｓ−5.01wt％Ni
−13.17wt％Cr−0.215wt％Ｎを含有する鋼塊お
よび鋼片の高温高速引張試験結果を示してある。
第１図の１は鍛造および分塊圧延（第１段階の熱
間加工）を想定して鋼塊表層部、第１図の２は厚
板圧延（第２段階の熱間加工）を想定して鋼片表
層部より夫々引張試験片を採取した。
高温高速引張試験における破断絞りが50％以下
の温度で加工すると、表面割れが発生し易くな
り、従つて、第１図から適正な加工温度は、１の
鍛造、分塊圧延において920〜1280℃、２の厚板
圧延においては820〜1300℃であることがわかる。
従つて、さらに操業上のバラツキを考慮に入れ、
熱間加工による表面割れを防止する加工温度とな
すためには、第１段階における鋼塊の加熱温度を
1150〜1250℃、加工仕上温度は950℃とし、第２
段階における鋼片の加熱温度は1050〜1270℃、仕
上温度は850℃以上とすることが必要となる。な
お、鋼塊および鋼片の加熱温度と夫々1150℃以上
および1050℃以上とするのは仕上温度を安定して
確保するためである。また、鋼塊および鋼片の加
熱時間については長くなるにつれて粒界酸化、低
融点化合物の溶融による粒界脆化をもたらし易く
なるので、操業上許容できる範囲で短時間加熱が
良好である。さらに、分塊圧延については加工温
度が1000℃以下になると急激に延性が低下するた
め、この温度以上で全圧下量の80％以上を加工す
るのがよい。さらに、本発明者は、0.05wt％Ｃ−
0.36wt％Si−21.79wt％Mn−0.013wt％Ｐ−
0.005wt％Ｓ−4.94wt％Ni−12.82wt％Cr−
0.21wt％Ｎを含有する鋼片を用いて液体ヘリウム
温度における各種機械的性質におよぼす厚板圧延
仕上温度および圧延後の冷却条件の影響について
調査したのでその結果を説明する。
第２図に4Kでの耐力とシヤルピ吸収エネルギ
ーにおよぼす処理条件の影響を示してある。第２
図において、１は圧延後空冷、２は圧延直後水
冷、３は圧延後５分間空冷した後水冷した鋼板を
示している。何れの処理材においても圧延仕上温
度が高くなるにつれて、耐力は低下し、靭性は向
上する傾向を示している。ここで、4Kにおいて
耐力が1200MPa以上、シヤルピ吸収エネルギー
が100J以上を示す製造条件は、圧延直後に水冷し
た鋼板では、仕上温度980〜1020℃、圧延後所定
時間空冷し、その後水冷した鋼板では950〜1010
℃であることがわかる。
しかしながら、第３図に示すように、圧延直後
水冷した鋼板１は鋼板表層部での靭性の低下が著
しく、このような不均質の材料は実用上問題が残
る可能性が強く、一方、圧延後所定時間空冷し、
その後水冷した鋼板２は表層部の靭性が大幅に向
上すると同時に1/4ｔ部の靭性の向上が認められ
る。また、板厚方向の硬度差（鋼板表層部と内部
との差）は、圧延直後の水冷材はHv（10Kg）で60
と非常に大きく、圧延後所定時間空冷後水冷した
鋼板では22と大幅に改善されている。
従つて、上記厚板圧延における鋼板表面割れ防
止と目標の機械的性質を得るための製造条件とし
ては、鋼片の加熱温度1050〜1270℃、圧延仕上温
度950〜1010℃とし、その後、所定時間の等温保
持或いは空冷を行なつた後、水冷することが好適
であることがわかるが、加熱温度が1250℃を越え
るとγ粒の粗大化が著しく、耐力の低下を来すよ
うになり、また、1150℃未満では950℃以上の仕
上温度が安定して確保することができなくなるの
で、加熱温度は最終的に1150〜1250℃と規定す
る。
さらに、圧延後に等温保持するのは、上記した
通り、板厚方向の不均質性改善に対し空冷と同等
或いはそれ以上の効果が得られるからであるが、
その後の水冷開始温度を800℃以上、停止温度を
500℃以下とすることが必要である。そして、800
〜500℃の温度範囲を空冷或いは徐冷すると粒界
へのCr炭化物の析出が顕著となり、靭性および
耐銹性の低下を招来する。
以上説明した通り、本発明の製造条件は核融合
炉超電導マグネツトという厳しい要求特性を満足
させるために規定されている。
次に、本発明に係る核融合炉超電導マグネツト
構造用非磁性鋼板の製造方法の実施例を説明し併
せて比較例を説明する。
実施例
第１表１は本発明に係る核融合炉超電導マグネ
ツト構造用非磁性鋼板の製造方法において使用す
る鋼塊の含有成分、成分割合を示し、第１表２は
本発明に係る核融合炉超電導マグネツト構造用非
磁性鋼板の製造方法の分塊圧延条件下に鋼塊の分
塊圧延（第１段階の熱間加工）を行つて鋼片を製
造した場合の、鋼片の表面割れ発生状況を示して
ある。比較例は鋼塊の含有成分、成分割合、並び
に、分塊圧延条件の何れも本発明に係る核融合炉
超電導マグネツト構造用非磁性鋼板の製造方法の
範囲外のものの結果を示してある。
この第１表２より本発明に係る核融合炉超電導
マグネツト構造用非磁性鋼板の製造方法における
分塊圧延条件下では、鋼片の表面割れは発生して
いないが、比較例においては全部に割れが発生し
ていることがわかる。
第２表１は本発明に係る核融合炉超電導マグネ
ツト構造用非磁性鋼板の製造方法において使用す
る鋼塊の含有成分、成分割合を示してあり、第２
表２は本発明に係る核融合炉超電導マグネツト構
造用非磁性鋼板の製造方法おける条件下に鋼塊を
分塊圧延（第１段階の熱間加工）を行つた鋼片
を、さらに、本発明に係る核融合炉超電導マグネ
ツト構造用非磁性鋼板の製造方法における条件下
において厚板圧延（第２段階の熱間加工）を行つ
て製造した鋼板の表面割れ発生状況を示してあ
る。比較例は厚板圧延の条件が本発明に係る核融
合炉超電導マグネツト構造用非磁性鋼板の製造方
法における条件の範囲外の結果である。
なお、この実施例における鋼片の分塊圧延条件
は、本発明に係る核融合炉超電導マグネツト構造
用非磁性鋼板の製造方法および比較例共に、鋼塊
加熱温度1200℃、圧延仕上温度960℃の同一条件
において行つた。
この第２表２より本発明に係る核融合炉超電導
マグネツト構造用非磁性鋼板の製造方法により製
造された鋼板には割れの発生はないが、比較例は
全て割れの発生が認められた。
第３表１は本発明に係る核融合炉超電導マグネ
ツト構造用非磁性鋼板の製造方法において使用す
る鋼塊の含有成分、成分割合を示してある。
第３表２は本発明に係る核融合炉超電導マグネ
ツト構造用非磁性鋼板の製造方法における一定の
分塊圧延条件（鋼塊加熱温度：1200℃、圧延仕上
温度：960℃）のもとに、鋼塊の分塊圧延を行い、
製造された鋼片を、これも本発明に係る核融合炉
超電導マグネツト構造用非磁性鋼板の製造方法に
おける条件下で厚板圧延を行い、さらに、引き続
いて本発明に係る核融合炉超電導マグネツト構造
用非磁性鋼板の製造方法の条件を満足する熱処理
を行つて非磁性鋼板を製造した際の厚板圧延並び
にその後の熱処理における製造条件を示したもの
である。
また、第３表３は、このようにして得られた非
磁性鋼板の機械的性質を調査した結果を示してあ
る。
比較例は分塊圧延条件は本発明に係る核融合炉
超電導マグネツト構造用非磁性鋼板の製造方法の
条件と同一であるが、厚板圧延条件、厚板圧延後
の熱処理条件および含有成分、成分割合の何れか
において、本発明に係る核融合炉超電導マグネツ
ト構造用非磁性鋼板の製造方法の条件を逸脱した
例である。
この第３表３の結果から、本発明に係る核融合
炉超電導マグネツト構造用非磁性鋼板の構造方法
によれば、何れも耐力1200MPa以上、シヤルピ
ー吸収エネルギー（VE）100J以上、および、破
壊靱性値（K1c）150MPam以上の優れた機械的
性質を具備した非磁性鋼板が製造されることがわ
かつた。
The present invention relates to a method for manufacturing a non-magnetic steel sheet, and more particularly, to a method for manufacturing a 4K non-magnetic steel sheet having high strength and high toughness for the structure of a superconducting magnet in a nuclear fusion reactor. Superconducting toroidal magnets, which are essential to nuclear fusion reactors, are cooled to liquid helium temperatures and operate under harsh conditions, including repeated high stress in a strong magnetic field. Therefore, a non-magnetic material with high yield strength and excellent fracture toughness at liquid helium temperatures is essential for the support structure of this magnet. Furthermore, since rusting reduces the insulation efficiency of the magnet, excellent rust resistance is also required. Conventionally, austenitic stainless steels such as SUS304L and SUS304LN have been used as structural materials for relatively small superconducting magnets. However, although these materials have excellent rust resistance and fracture toughness, they have low yield strength and
Due to the poor stability of austenite, it has the disadvantage that magnetic permeability easily deteriorates due to plastic deformation. Also, high Mn-based austenitic steels, e.g.
18Mn-5Cr steel, 14Mn-2Ni-2Cr steel, etc. have high yield strength and low content of expensive Ni, making them excellent in economy, but they have low fracture toughness and poor rust resistance. It has disadvantages. On the other hand, Ti alloys, Ni alloys, AI alloys, etc. are also being considered as candidate materials, but they are too expensive to be used as structural materials in large quantities and have the drawbacks of low fracture toughness. Therefore, these conventional materials are not sufficient as support structure materials for superconducting magnets for nuclear fusion reactors. The present invention was developed in view of the drawbacks and problems of various materials for use in superconducting magnet support structures as explained above . c) 150MPa√
A method for manufacturing a high-Mn nonmagnetic steel sheet for extremely low temperatures, which is useful as a support structure material for large superconducting magnets, has a hardness of at least m or more, has excellent rust resistance, and has small variations in mechanical properties in the thickness direction. It is about providing. Method for manufacturing a non-magnetic steel plate for fusion reactor superconducting magnet structure according to the present invention (in the following explanation, it may simply be referred to as the method for manufacturing a non-magnetic steel plate according to the present invention).
is C0.01~0.10wt%, Si0.01~1.00wt%, Mn16
~30wt%, P0.03wt% or less, S0.01wt% or less,
Ni3~10wt%, Cr12~20wt%, N0.100~0.300wt
%, and wt%Mn×wt%Cr/wt%Ni
≦65, 0.200wt%≦C+N≦0.300wt%,
1150% steel ingot consisting of balance Fe and unavoidable impurities
After heating to ~1250℃, forging or blooming rolling to 950℃
Finished at the above temperature, and after cooling, the steel billet is
After heating to 1150~1250℃, hot rolling is completed at a temperature of 950~1010℃, then 1~60℃ at a temperature of 800℃ or higher.
Proof strength of 1200 MPa or more at liquid helium temperature, characterized by isothermal holding for 10 minutes or air cooling, followed by water cooling to a temperature of 500°C or less, and Sharalpy absorption energy.
100J or more and fracture toughness value (K 1 c) 150MPa√
This is a method for producing a high Mn stainless steel nonmagnetic steel plate for cryogenic use, which has the above features and is used as a structural material for a superconducting magnet in a fusion reactor, and has small variations in mechanical properties in the thickness direction. A method for manufacturing a non-magnetic steel plate for a superconducting magnet structure in a fusion reactor according to the present invention will be described in detail below. First, the components and component ratios of the steel used in the method for manufacturing a non-magnetic steel sheet according to the present invention will be explained. C is an element that is effective in stabilizing austenite and improving its yield strength. If the content is less than 0.01wt%, this effect will be small, and if the content exceeds 0.10wt%, the toughness will decrease and the durability will decrease. It begins to lose its rustiness. Therefore, the C content is set to 0.01 to 0.10 wt%. Si is necessary for deoxidation during steel making, and is an element that increases the fluidity of molten steel during ingot making, reduces internal defects in steel ingots, and is also effective in improving yield strength, and its content is 0.01wt%. If the content is less than 1.00 wt%, there will be no such effect, and if the content exceeds 1.00 wt%, the high temperature ductility will be inhibited and the toughness will be reduced. Therefore, the Si content is set to 0.01 to 1.00 wt%. Mn is effective in stabilizing austenite, improving toughness, and increasing the solid solubility limit of N.
This effect is small below 16wt%, and 30wt%
If the content exceeds 5%, δ ferrite is likely to be formed, resulting in a decrease in hot workability and toughness. Then,
The Mn content is 16 to 30 wt%. Both P and S are impurity elements that impair hot workability and toughness, and are preferably as low as possible, but in consideration of economic efficiency, P and S are set at 0.03 wt% or less and S at 0.01 wt% or less. Ni is an element that is effective in stabilizing austenite, improving toughness, and suppressing the formation of δ ferrite.If the content is less than 3wt%, these excellent effects will be small, and if the content exceeds 10wt%, the toughness will decrease. saturation and impairs economic efficiency. Then,
The Ni content is 3 to 10 wt%. Cr is an element that is necessary to impart rust resistance and improves yield strength, and its content is
If it is less than 12wt%, rust resistance will not be sufficient, and
Excessive content exceeding 20 wt% promotes the formation of δ ferrite, reducing hot workability and toughness. Therefore, the Ni content is set to 12 to 20 wt%. N is an element effective in stabilizing austenite and improving its yield strength. If the content is less than 0.100, this effect is small, and if the content exceeds 0.300 wt%, the toughness is greatly reduced. Therefore, the N content is
The content should be 0.100-0.300wt%. Both C and N are elements that strongly stabilize austenite and have an extremely large effect on yield strength and toughness.If the C+N content is less than 0.200wt%, the effect of stabilizing austenite and increasing yield strength is small; If the content exceeds %, the toughness will be significantly reduced. Therefore, the C+N content is set to 0.200≦C+N≦0.300wt%. When the Mn and Cr contents increase, the generation of δ-ferrite becomes significant due to their additive effects, resulting in a significant loss of hot workability and toughness.Also, Ni has the effect of suppressing the formation of δ-ferrite. Therefore, in order to prevent deterioration of hot workability and toughness due to the formation of δ ferrite,
The content of Mn, Cr and Ni is wt%Mn×wt%
It is necessary to make Cr/wt%Ni≦65. Next, the manufacturing conditions of the method for manufacturing a non-magnetic steel sheet according to the present invention will be explained. In the present invention, when manufacturing a nonmagnetic steel plate for the structure of a superconducting magnet in a fusion reactor, hot working is carried out in two stages. That is, the first stage hot working is a steel ingot forging or blooming rolling process, and the second stage hot working is a thick plate rolling process of the steel billet produced by the first stage working. . In addition, all of these hot processes are performed under specific conditions (designation of heating temperature and processing temperature range).
This will be implemented in The purpose of hot working in this first stage is to homogenize the internal quality of the steel material by destroying the coarse dendritic structure of the steel ingot, refining it, and crimping defects such as dents. There is also
The purpose of the second stage hot working is to impart a specific product shape and to obtain targeted mechanical properties by adjusting the grain size. In addition, in order to achieve this purpose, it is possible to perform thick plate rolling from a steel ingot through a single hot working process, but this would require a long time for rolling and the temperature of the steel ingot would drop significantly. This is not preferable because it causes the problem of surface cracking as described later. Therefore, in the method of manufacturing a non-magnetic steel plate for the structure of a superconducting magnet for a fusion reactor according to the present invention, two-step hot working is carried out as an essential step in order to prevent the occurrence of surface cracks. In general, high-Mn austenitic steel has poor hot workability compared to carbon steel, low-alloy steel, etc., and if it is not forged or rolled under appropriate conditions, cracks will occur on the surface of the billet or steel plate, resulting in a decrease in yield. invite. Therefore,
The inventors first conducted research on appropriate manufacturing conditions to prevent cracks from occurring due to hot working. In Figure 1, 0.07wt%C-0.27wt%Si-21.38wt
%Mn−0.015wt%P−0.005wt%S−5.01wt%Ni
The results of high-temperature, high-speed tensile tests of steel ingots and slabs containing -13.17wt%Cr-0.215wt%N are shown.
1 in Figure 1 assumes forging and blooming rolling (the first stage of hot working) and indicates the surface layer of the steel ingot, and 2 in Figure 1 assumes thick plate rolling (the second stage of hot working). Tensile test pieces were taken from the surface layer of each steel piece. Surface cracking is likely to occur if processing is performed at a temperature below 50% of the area of area at break in the high-temperature, high-speed tensile test. Therefore, from Figure 1, the appropriate processing temperature is 920 to 1280°C for forging and blooming in 1. It can be seen that the temperature in the thick plate rolling of No. 2 is 820 to 1300°C.
Therefore, taking into account operational variations,
In order to achieve a processing temperature that prevents surface cracking due to hot working, the heating temperature of the steel ingot in the first stage must be
1150-1250℃, processing finishing temperature is 950℃,
The heating temperature of the steel slab in this step must be 1050 to 1270°C, and the finishing temperature must be 850°C or higher. Note that the heating temperatures of the steel ingot and the steel billet are set to 1150°C or higher and 1050°C or higher, respectively, in order to ensure a stable finishing temperature. Furthermore, as the heating time of the steel ingot and steel slab becomes longer, it becomes easier to cause grain boundary oxidation and grain boundary embrittlement due to melting of low-melting compounds, so it is better to heat the steel ingot and slab for a short time within an operationally acceptable range. Furthermore, in the case of blooming rolling, since the ductility decreases rapidly when the processing temperature is below 1000°C, it is preferable to perform processing at a temperature above this temperature for 80% or more of the total reduction. Furthermore, the inventor has determined that 0.05wt% C-
0.36wt%Si−21.79wt%Mn−0.013wt%P−
0.005wt%S-4.94wt%Ni-12.82wt%Cr-
Using steel slabs containing 0.21wt%N, we investigated the effects of plate rolling finishing temperature and post-rolling cooling conditions on various mechanical properties at liquid helium temperature.The results will be explained below. Figure 2 shows the influence of processing conditions on the yield strength and Shalpy absorbed energy at 4K. Second
In the figure, 1 indicates a steel plate that was air-cooled after rolling, 2 was water-cooled immediately after rolling, and 3 was a steel plate that was air-cooled for 5 minutes after rolling and then water-cooled. In any of the treated materials, as the rolling finishing temperature increases, the yield strength tends to decrease and the toughness tends to improve. Here, the manufacturing conditions that show proof stress of 1200 MPa or more and Shalpy absorbed energy of 100 J or more at 4K are: a finishing temperature of 980 to 1020°C for a steel plate that is water-cooled immediately after rolling, and a finishing temperature of 950°C for a steel plate that is air-cooled for a predetermined period of time after rolling and then water-cooled. ~1010
It can be seen that the temperature is ℃. However, as shown in Fig. 3, the steel plate 1 that was water-cooled immediately after rolling showed a significant decrease in toughness at the surface layer of the steel plate, and there is a strong possibility that such a heterogeneous material would pose a problem in practical use. Air cool for a predetermined time,
Steel plate 2, which was then water-cooled, had significantly improved toughness in the surface layer and, at the same time, an improvement in toughness in the 1/4t portion. In addition, the hardness difference in the sheet thickness direction (difference between the surface layer and the inside of the steel sheet) is 60 Hv (10Kg) for water-cooled material immediately after rolling.
This is extremely large, and the steel plate that was air-cooled for a predetermined period of time after rolling and then water-cooled had a significant improvement of 22. Therefore, the manufacturing conditions for preventing steel plate surface cracking and obtaining the target mechanical properties in the thick plate rolling mentioned above are as follows: the heating temperature of the steel billet is 1050 to 1270°C, the rolling finishing temperature is 950 to 1010°C, and then the heating temperature is 1050 to 1270°C, and the rolling finishing temperature is 950 to 1010°C. It can be seen that isothermal holding or air cooling followed by water cooling is suitable; however, if the heating temperature exceeds 1250°C, the γ grains become coarser and the yield strength decreases. If the temperature is lower than 1150°C, it will not be possible to stably secure a finishing temperature of 950°C or higher, so the final heating temperature is specified as 1150 to 1250°C. Furthermore, the reason for holding the temperature after rolling is that, as mentioned above, it is as effective as or more effective than air cooling in improving non-uniformity in the thickness direction.
After that, the water cooling start temperature should be 800℃ or higher, and the stop temperature should be 800℃ or higher.
It is necessary to keep the temperature below 500℃. And 800
When air-cooled or slowly cooled in the temperature range of ~500°C, precipitation of Cr carbides at grain boundaries becomes noticeable, leading to a decrease in toughness and rust resistance. As explained above, the manufacturing conditions of the present invention are specified in order to satisfy the strict required characteristics of a fusion reactor superconducting magnet. Next, examples of the method for manufacturing a non-magnetic steel plate for a superconducting magnet structure of a fusion reactor according to the present invention will be described, and a comparative example will also be described. Examples Table 1 1 shows the components and component ratios of the steel ingot used in the method for producing a non-magnetic steel plate for the structure of a superconducting magnet in a fusion reactor according to the present invention, and Table 1 2 shows the components and proportions of the steel ingot used in the method for manufacturing a non-magnetic steel plate for the structure of a fusion reactor superconducting magnet according to the present invention. Occurrence of surface cracks in steel billets when steel billets are produced by blooming a steel ingot (first stage hot working) under the blooming rolling conditions of the method for producing non-magnetic steel sheets for superconducting magnet structures is shown. The comparative example shows the results of steel ingots containing components, component ratios, and blooming rolling conditions that are all outside the range of the method for manufacturing a nonmagnetic steel sheet for a superconducting magnet structure of a fusion reactor according to the present invention. As can be seen from Table 1 and 2, under the blooming rolling conditions in the manufacturing method of the non-magnetic steel sheet for the structure of a superconducting magnet in a fusion reactor according to the present invention, no surface cracking occurred on the steel slab, but in the comparative example, cracking occurred on the entire surface. It can be seen that this is occurring. Table 2 1 shows the components and component ratios of the steel ingot used in the method for manufacturing a non-magnetic steel plate for the structure of a superconducting magnet in a fusion reactor according to the present invention.
Table 2 shows the steel billets obtained by blooming a steel ingot (first stage hot working) under the conditions of the method for producing a non-magnetic steel plate for the structure of a superconducting magnet in a fusion reactor according to the present invention. The figure shows the occurrence of surface cracks in a steel plate produced by thick plate rolling (second stage hot working) under the conditions of the method for producing a non-magnetic steel plate for the structure of a superconducting magnet in a fusion reactor. The comparative example is a result in which the thick plate rolling conditions are outside the range of the conditions in the method for manufacturing a non-magnetic steel plate for the structure of a superconducting magnet for a fusion reactor according to the present invention. Note that the blooming rolling conditions for the steel billet in this example were as follows: the ingot heating temperature was 1200°C, and the rolling finishing temperature was 960°C, both in the manufacturing method of a non-magnetic steel plate for fusion reactor superconducting magnet structure according to the present invention and in the comparative example. It was conducted under the same conditions. As shown in Table 2, there was no cracking in the steel sheets manufactured by the method of manufacturing non-magnetic steel sheets for superconducting magnet structures in fusion reactors according to the present invention, but cracks were observed in all of the comparative examples. Table 3 shows the components and component ratios of the steel ingot used in the method of manufacturing a non-magnetic steel plate for superconducting magnet structure of a fusion reactor according to the present invention. Table 3 shows the following conditions under certain blooming rolling conditions (steel ingot heating temperature: 1200°C, finishing rolling temperature: 960°C) in the method for manufacturing a non-magnetic steel plate for the structure of a fusion reactor superconducting magnet according to the present invention. Performs blooming rolling of steel ingots,
The manufactured steel billet is subjected to plate rolling under the conditions of the method for manufacturing a non-magnetic steel plate for a fusion reactor superconducting magnet structure, which also relates to the present invention, and is then subsequently processed into a fusion reactor superconducting magnet structure according to the present invention. This figure shows manufacturing conditions for thick plate rolling and subsequent heat treatment when a nonmagnetic steel sheet is manufactured by heat treatment that satisfies the conditions of the method for manufacturing a nonmagnetic steel sheet for use. Further, Table 3 shows the results of investigating the mechanical properties of the non-magnetic steel sheets thus obtained. In the comparative example, the blooming conditions are the same as those of the method for producing a non-magnetic steel sheet for the structure of a superconducting magnet for a fusion reactor according to the present invention, but the thick plate rolling conditions, the heat treatment conditions after thick plate rolling, and the ingredients and components This is an example in which any of the ratios deviates from the conditions of the method for manufacturing a non-magnetic steel plate for the structure of a superconducting magnet for a fusion reactor according to the present invention. From the results in Table 3, it can be seen that according to the method of constructing the non-magnetic steel plate for the structure of a superconducting magnet in a fusion reactor according to the present invention, the yield strength is 1200 MPa or more, the Charpy absorbed energy (VE) is 100 J or more, and the fracture toughness value is It was found that a non-magnetic steel sheet with excellent mechanical properties of (K 1 c) of 150 MPam or more can be produced.
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】
以上説明したように、本発明に係る核融合炉超
電導マグネツト構造用非磁性鋼板の製造方法は上
記の構成を有しているものであるから、超電導マ
グネツト支持構造用材料として、液体ヘリウム温
度における耐力、シヤルピ吸収エネルギーおよび
破壊靭性に優れ、さらに、耐銹性にも優れている
鋼板が得られるという効果を有する。[Table] As explained above, since the method for manufacturing a non-magnetic steel plate for a superconducting magnet structure of a fusion reactor according to the present invention has the above configuration, liquid helium is used as a material for a superconducting magnet support structure. This has the effect of producing a steel plate that is excellent in yield strength at temperature, Schalpy absorbed energy, and fracture toughness, and also has excellent rust resistance.
第１図は試験温度と破断絞りとの関係を示す
図、第２図は圧延仕上温度とvE4(J)および4Kでの
0.2％Y.S.（MPa）との関係を示す図、第３図は試
験片採取位置とvE77(J)との関係を示す図である。
Figure 1 shows the relationship between test temperature and fracture reduction area, and Figure 2 shows the relationship between finishing rolling temperature and vE 4 (J) and 4K.
A diagram showing the relationship between 0.2% YS (MPa) and FIG. 3 is a diagram showing the relationship between the test piece sampling position and vE 77 (J).
Claims (1)
鋼塊を1150〜1250℃に加熱後、鍛造或いは分塊圧
延を950℃以上の温度で終了し、放冷後さらに、
その鋼片を1150〜1250℃に加熱後950〜1010℃の
温度で熱間圧延を終了し、その後800℃以上の温
度で１〜60分間の等温保持或いは空冷後、500℃
以下の温度まで水冷することを特徴とする液体ヘ
リウム温度で耐力1200MPa以上、シヤルピ吸収
エネルギ100J以上および破壊靭性値（K1c）
150MPa√以上を有し、かつ、板厚方向の機械
的性質のバラツキの小さい核融合炉超電導マグネ
ツトの構造材料として用いられる極低温用高Mn
ステンレス系非磁性鋼板の製造方法。[Claims] 1 C0.01-0.10wt%, Si0.01-1.00wt%, Mn16-30wt%, P0.03wt% or less, S0.01wt% or less, Ni3-10wt%, Cr12-20wt%, A steel ingot containing 0.100 to 0.300wt% of N, and satisfying wt%Mn×wt%Cr/wt%Ni≦65, 0.200wt%≦C+N≦0.300wt%, with the balance consisting of Fe and unavoidable impurities. After heating to 1150-1250℃, forging or blooming is completed at a temperature of 950℃ or higher, and after cooling,
After heating the steel slab to 1150-1250℃, hot rolling is completed at a temperature of 950-1010℃, then isothermally held at a temperature of 800℃ or higher for 1 to 60 minutes, or after air cooling, it is heated to 500℃.
At liquid helium temperature, which is characterized by water cooling to the following temperatures, yield strength is 1200 MPa or more, Sharalpy absorbed energy is 100 J or more, and fracture toughness value (K 1 c)
A high Mn material for cryogenic use that is used as a structural material for superconducting magnets in fusion reactors, which has a strength of 150 MPa√ or more and has small variations in mechanical properties in the thickness direction.
A method for manufacturing stainless steel non-magnetic steel sheets.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59045142A JPS60190516A (en) | 1984-03-09 | 1984-03-09 | Production of nonmagnetic steel sheet for constructing superconductive magnet for nuclear fission reactor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59045142A JPS60190516A (en) | 1984-03-09 | 1984-03-09 | Production of nonmagnetic steel sheet for constructing superconductive magnet for nuclear fission reactor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60190516A JPS60190516A (en) | 1985-09-28 |
| JPH0536482B2 true JPH0536482B2 (en) | 1993-05-31 |
Family
ID=12711026
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59045142A Granted JPS60190516A (en) | 1984-03-09 | 1984-03-09 | Production of nonmagnetic steel sheet for constructing superconductive magnet for nuclear fission reactor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60190516A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62156258A (en) * | 1985-12-27 | 1987-07-11 | Kobe Steel Ltd | Nonmagnetic cold rolled steel sheet for sheath of superconductive wire having superior cold workability |
| JPS62271308A (en) * | 1986-05-19 | 1987-11-25 | 日本原子力研究所 | Superconductive cable conductor |
-
1984
- 1984-03-09 JP JP59045142A patent/JPS60190516A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60190516A (en) | 1985-09-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR20020088425A (en) | Hot rolled wire or steel bar for machine structural use capable of dispensing with annealing, and method for producing the same | |
| JPS61270356A (en) | Austenitic stainless steels plate having high strength and high toughness at very low temperature | |
| JPH0536481B2 (en) | ||
| JP3842836B2 (en) | Method for producing high-tensile steel with excellent low-temperature toughness | |
| JPS62270721A (en) | Production of high-mn austenitic stainless steel for cryogenic service | |
| JPH06316736A (en) | Ni-fe magnetic alloy excellent in magnetic property and producibility and its production | |
| JPH06322440A (en) | Method for rolling high manganese nonmagnetic steel slab | |
| JP2008013812A (en) | High toughness and high tensile strength thick steel plate and its production method | |
| US4533391A (en) | Work-hardenable substantially austenitic stainless steel and method | |
| JPS62205230A (en) | Manufacture of steel plate for low temperature service superior in characteristic for stopping brittle cracking propagation | |
| JPH0250931A (en) | Manufacture of ferromagnetic ni-fe alloy and slab of the same alloy having excellent surface properties | |
| KR101657848B1 (en) | Soft magnetic steel having excellent forging characteristic, soft magnetic part and method of manufacturing the same | |
| JPH0536482B2 (en) | ||
| JPH0121845B2 (en) | ||
| JPH0579727B2 (en) | ||
| JPH05195156A (en) | High-manganese ultrahigh tensile strength steel excellent in toughness in heat affected zone and its production | |
| CN115652210B (en) | Austenitic stainless steel billet with ultralow carbide content and manufacturing method thereof | |
| JP3439062B2 (en) | High Mn stainless steel with excellent hot workability and cryogenic toughness | |
| JPH07316653A (en) | Production of thick stainless steel plate excellent in very low temperature characteristic | |
| JPH0158249B2 (en) | ||
| JPH02145723A (en) | Manufacture of thick steel material having excellent direct current magnetization characteristics | |
| JPH07188817A (en) | Ni-fe magnetic alloy excellent in magnetic property and workability and its production | |
| KR101461714B1 (en) | Steel wire rod and steel wire having excellent drawability and method for manufacturing thereof | |
| JPH0790366A (en) | Production of high mn stainless series nonmagnetic steel slab good in surface property | |
| JP2003155542A (en) | HIGH NONMAGNETIC Mn STEEL FOR SUPERCONDUCTING MAGNET HAVING EXCELLENT HOT WORKABILITY AND HEATING EMBRITTLEMENT RESISTANCE AFTER HEAT TREATMENT FOR PRODUCING SUPERCONDUCTING MAGNET |