JPH0347946A - Manufacture of boron-containing austenitic stainless steel having excellent hot workability as well as cold ductility and toughness - Google Patents
Manufacture of boron-containing austenitic stainless steel having excellent hot workability as well as cold ductility and toughnessInfo
- Publication number
- JPH0347946A JPH0347946A JP18243189A JP18243189A JPH0347946A JP H0347946 A JPH0347946 A JP H0347946A JP 18243189 A JP18243189 A JP 18243189A JP 18243189 A JP18243189 A JP 18243189A JP H0347946 A JPH0347946 A JP H0347946A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- toughness
- hot
- powder
- stainless steel
- 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.)
- Pending
Links
- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims abstract description 19
- 229910052796 boron Inorganic materials 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title claims description 13
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 title claims description 12
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 52
- 239000010959 steel Substances 0.000 claims abstract description 52
- 239000000843 powder Substances 0.000 claims abstract description 27
- 238000001513 hot isostatic pressing Methods 0.000 claims abstract description 21
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 13
- 238000005098 hot rolling Methods 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract 3
- 238000000034 method Methods 0.000 claims description 23
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 18
- 238000001192 hot extrusion Methods 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 15
- 229910052742 iron Inorganic materials 0.000 claims description 13
- 239000012535 impurity Substances 0.000 claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 claims description 4
- 239000010935 stainless steel Substances 0.000 claims description 3
- 229910001566 austenite Inorganic materials 0.000 claims description 2
- 239000002915 spent fuel radioactive waste Substances 0.000 abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 3
- 239000011148 porous material Substances 0.000 abstract description 2
- 238000007664 blowing Methods 0.000 abstract 1
- 238000005096 rolling process Methods 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 10
- 238000007711 solidification Methods 0.000 description 9
- 230000008023 solidification Effects 0.000 description 9
- 238000010521 absorption reaction Methods 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 6
- 230000007797 corrosion Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 5
- 238000001125 extrusion Methods 0.000 description 5
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 3
- 238000000889 atomisation Methods 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000005204 segregation Methods 0.000 description 3
- 229910052582 BN Inorganic materials 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 101100103010 Schizosaccharomyces pombe (strain 972 / ATCC 24843) wss2 gene Proteins 0.000 description 1
- 206010040844 Skin exfoliation Diseases 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000009694 cold isostatic pressing Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005491 wire drawing Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
Abstract
Description
【発明の詳細な説明】
「発明の目的」
本発明は、熱間加工性および常温の延性、靭性に優れた
含ボロンオーステナイト系ステンレス鋼材の製造方法に
係り、熱間加工性および常温延性や靭性に優れた使用済
み核燃料キャスク用Ｂ含有Ｔ系ＳＵＳ鋼材の好ましい製
造方法を提供しようとするものである。Detailed Description of the Invention Object of the Invention The present invention relates to a method for producing a boron-containing austenitic stainless steel material that has excellent hot workability, room temperature ductility, and toughness. The present invention aims to provide a preferable method for producing B-containing T-series SUS steel material for spent nuclear fuel casks with excellent properties.
（産業上の利用分野）
使用済み核燃料の輸送ないし貯蔵用キャスクのような燃
料ハスケソト用などの原子力用材！１として使用される
ボロン含有オーステナイト系ステンレス鋼板などの製造
技術。(Industrial application field) Nuclear power materials such as casks for transporting or storing spent nuclear fuel! Manufacturing technology for boron-containing austenitic stainless steel sheets used as 1.
（従来の技術）
Ｂを０．３〜３．０ｗｔ％含有したオーステナイト系ス
テンレス鋼は、熱中性子吸収性に優れ、使用済み核燃料
の輸送及び貯蔵用キャスクの燃料バスケット用材料とし
て使用される。しかし、Ｂは、凝固時における共晶反応
により硬くて脆いホウ化物（（Ｆｅ、 Ｃｒ）Ｊ）を形
成するため、含ボロンオーステナイト系ステンレス鋼の
熱間加工性は、一般に極めて低い。そのため、圧延時、
耳割れ等の割れが発生しやすい。また、このオーステナ
イト系ステンレス鋼板は、バスケット用に角パイプに成
形加工される場合が多いが、常温の延性が低いため、曲
げ半径等の条件が大きく制約され、更に、使用時、たと
えば、輸送時の衝突・落下等の事故を想定すると、靭性
が低いために安全性確保に多大な努力を払わねばならな
い。前記含Ｂオーステナイト系ステンレス鋼中のＢ含有
量が増加するに従って、熱中性子吸収性能は向」二する
が、」二記したような熱間加工性、常温の延性、靭性は
、劣化する。(Prior Art) Austenitic stainless steel containing 0.3 to 3.0 wt% of B has excellent thermal neutron absorption properties and is used as a material for fuel baskets in casks for transporting and storing spent nuclear fuel. However, since B forms a hard and brittle boride ((Fe, Cr)J) through a eutectic reaction during solidification, the hot workability of boron-containing austenitic stainless steels is generally extremely low. Therefore, during rolling,
Cracks such as ear cracks are likely to occur. In addition, this austenitic stainless steel sheet is often formed into square pipes for baskets, but because of its low ductility at room temperature, conditions such as bending radius are severely restricted. Considering accidents such as collisions and falls, great efforts must be made to ensure safety due to the low toughness. As the B content in the B-containing austenitic stainless steel increases, the thermal neutron absorption performance improves, but the hot workability, room temperature ductility, and toughness described above deteriorate.
このような、含ボロンオーステナイト系ステンレス鋼板
の従来の製造方法は、通常の鋼と同様、溶解−鋳造−圧
延プロセスで製造されている。圧延時、割れの発生を抑
制するため、例えば、特開昭６４−８２２Ｌ特開昭６３
−５０４２９に示されるように圧延温度は厳しく制限さ
れる。The conventional manufacturing method for such a boron-containing austenitic stainless steel sheet is a melting-casting-rolling process, similar to ordinary steel. In order to suppress the occurrence of cracks during rolling, for example, JP-A-64-822L, JP-A-63
-50429, the rolling temperature is strictly limited.
また、オーステナイト系ステンレス粉末とボロンナイト
ライド（ＢＮ）粉末を混合し、熱間等方圧加圧により鋼
片に成型した後、熱間圧延するという（特開昭６３−２
９３１３９の如き）が提案されている。熱中性子を吸収
することが目的である使用済み核燃料の輸送及び貯蔵用
キャスクの燃料バスケット用材料としては、ＢＮが均一
・に分布していなければならないが、オーステナイト系
ステンレス粉末とボロンナイト（ＢＮ）粉末を均一に混
合するのは、技術的に困難である。In addition, austenitic stainless steel powder and boron nitride (BN) powder are mixed, formed into a steel billet by hot isostatic pressing, and then hot rolled (JP-A-63-2
93139) have been proposed. As materials for the fuel basket of spent nuclear fuel transportation and storage casks whose purpose is to absorb thermal neutrons, BN must be uniformly distributed, but austenitic stainless steel powder and boronite (BN) are Mixing powders uniformly is technically difficult.
（発明が解決しようとする課題）
上述したように、Ｂを０．１〜３．Ｑｉ１ｔ％含有した
オーステナイト系ステンレス鋼は、凝固時、ポウ化物（
（Ｆｅ、 Ｃｒ）ｚＢ）を晶出する。ボウ化物は硬くて
脆いので、加工をすると、ホウ化物それ自身が割れたり
、地鉄との界面が剥離しやすい。晶出したホウ化物が粗
大なほど、上記の割れや剥離は大型化し、熱間加工性や
常温の延性・靭性が劣る結果となる。すなわち、含Ｂオ
ーステナイト系ステンレス鋼の熱間加工性や常温の延性
・靭性を支配しているのは、ホウ化物（（Ｆｅ、 Ｃｒ
） ２Ｂ）のサイズであると言えるが、通常の溶解−鋳
造法にて製造された含Ｂオーステナイト系ステンレス鋼
は、凝固速度が低いため、数μｍ以上の粗大なホウ化物
（（Ｆｅ、 Ｃｒ）ｚＢ）を晶出する。従って、このよ
うな方法による含Ｂオーステナイト系ステンレス鋼の熱
間加工性、常温の延性、靭性は、著しく低いことになり
好ましい利用をなし得ない。(Problem to be Solved by the Invention) As mentioned above, B is 0.1 to 3. Austenitic stainless steel containing 1t% Qi contains poride (
(Fe, Cr)zB) is crystallized. Since boride is hard and brittle, when processed, the boride itself tends to break or the interface with the base steel tends to peel off. The coarser the crystallized boride, the larger the cracks and peelings described above become, resulting in poor hot workability and poor ductility and toughness at room temperature. In other words, borides ((Fe, Cr,
) 2B), but B-containing austenitic stainless steel manufactured by the normal melting and casting method has a low solidification rate, so it contains coarse borides ((Fe, Cr) of several μm or more). zB) is crystallized. Therefore, the hot workability, room temperature ductility, and toughness of the B-containing austenitic stainless steel obtained by such a method are extremely low, so that it cannot be used preferably.
「発明の構成」
（課題を解決するための手段）
本発明は」二記した、しうな従来のものの問題点を解消
するように検討して創案されたものであって、以下の如
くである。``Structure of the Invention'' (Means for Solving the Problems) The present invention has been developed after consideration to solve the problems of the conventional products as mentioned in the following two sections. .
１、重量％で、１３：０．３〜３．０％、ｃ：ｏ、ｏｓ
％以下、Ｓｉ： ０．０１〜２．０％、Ｍｎ ： ２．
０％以下、Ｃｒ：１６．０〜２０．０％、Ｎｉ ：
８．０〜１５．０％、門。＝３．０％以下を含有し、残
部が鉄および不可避的不純物よりなる２０メッシュより
細かいアトマイズ粉末を、加熱温度１０００〜１２５０
℃、圧力８００ｋｇ／ｃｍ”以」二の条件で熱間等方圧
加圧により鋼片に成形した後、熱間圧延することを特徴
とする、熱間加工性および常温の延性、靭性に優れた含
ボロンオーステナイト系ステンレス鋼材の製造方法。1. In weight%, 13:0.3-3.0%, c:o, os
% or less, Si: 0.01-2.0%, Mn: 2.
0% or less, Cr: 16.0-20.0%, Ni:
8.0-15.0%, phylum. = 3.0% or less, and the balance is iron and unavoidable impurities.
It is characterized by its excellent hot workability, ductility and toughness at room temperature, which is characterized by being formed into a steel billet by hot isostatic pressing under the conditions of 800 kg/cm" or less at a pressure of 800 kg/cm" or less, and then hot rolling. A method for manufacturing a boron-containing austenitic stainless steel material.
２、重量％で、Ｂ：ｏ、ａ〜３．０％、Ｃ： ０．０８
％以下、Ｓｉ：０．０１〜２．０％、Ｍｎ ： ２．０
％以下、Ｃｒ：１６．０〜２０．０％、Ｎｉ：８．０〜
１５．０％、ＭＯ＝３．０％以下を含有し、残部が鉄お
よび不可避的不純物よりなる２０メッシュより細かいア
トマイズ粉末を、１０５０〜１１７０℃の温度範囲で熱
間押出しにて鋼片に成形した後、熱間圧延することを特
徴とする、熱間加工性および常温の延性、靭性に優れた
含ボロンオーステナイト系ステンレス鋼材の製造方法。2. In weight%, B: o, a ~ 3.0%, C: 0.08
% or less, Si: 0.01-2.0%, Mn: 2.0
% or less, Cr: 16.0-20.0%, Ni: 8.0-
15.0%, MO=3.0% or less, and the balance is iron and unavoidable impurities. Atomized powder finer than 20 mesh is formed into a steel billet by hot extrusion at a temperature range of 1050 to 1170°C. A method for producing a boron-containing austenitic stainless steel material that has excellent hot workability, ductility and toughness at room temperature, and then hot rolling.
（作用）
」−記したような本発明の作用関係を説明するに、先ず
成分の限定理由は以−ドの如くである。(Function) To explain the operational relationship of the present invention as described above, first, the reasons for limiting the components are as follows.
Ｉ３ば、自然状態で約２０％の同位元素１０Ｂを含んで
おり、”Ｂは中性子吸収断面積の大きい元素であり、中
性子遮蔽のために使用する木鋼板においては、最も重要
な元素であって、０．３％以下では、熱中性子の吸収性
能が十分でなく、−・方３．０％以１−では、ホウ化物
の体積率が４０％以−ヒにも達し、熱間加工性や常温の
延性、靭性が著しく劣化するので、Ｂ：０．３〜３．０
％に限定した。I3 contains about 20% isotope 10B in its natural state, and B is an element with a large neutron absorption cross section, and is the most important element in wood steel plates used for neutron shielding. If it is less than 0.3%, the thermal neutron absorption performance is insufficient, and if it is more than 3.0%, the volume fraction of boride reaches more than 40%, which deteriorates hot workability. B: 0.3 to 3.0 because the ductility and toughness at room temperature will deteriorate significantly.
%.
Ｃは、０．０８％以上になると、炭化物が生成しやず（
、そのため耐食性が劣化するので、Ｃ：０．０８％以下
と限定した。When C exceeds 0.08%, carbides are not formed (
As a result, the corrosion resistance deteriorates, so C: was limited to 0.08% or less.
Ｓｉ は、脱酸のために添加する必要があり、０．０１
％以下では脱酸が十分でなく、又２．０％を越えると脆
化が生じるため、Ｓｉ：０．０１〜２．０％に限定した
。Ｍｎも脱酸効果を持つ元素であるが、２．０％をこえ
ると耐食性が低下するので、Ｍｎ ：２．０％以下と限
定した。Si needs to be added for deoxidation and is 0.01
% or less, deoxidation is not sufficient, and if it exceeds 2.0%, embrittlement occurs, so Si: was limited to 0.01 to 2.0%. Mn is also an element that has a deoxidizing effect, but if it exceeds 2.0%, corrosion resistance decreases, so Mn was limited to 2.0% or less.
Ｃｒは耐食性を保持するために１６．０％は必要であり
、また２０．０％を越えるとσ相が析出し脆化しやすく
なるので、Ｃｒ：１６．０〜２０．０％に限定した。Cr is required to be 16.0% to maintain corrosion resistance, and if it exceeds 20.0%, the σ phase will precipitate and become brittle, so Cr was limited to 16.0 to 20.0%.
Ｎｉ は、組織をオーステナイトにするのに必要な元素
であり、そのためには８．０％以上必要である。しかし
て上限については、高価な元素であるため、Ｎｉ：８．
０〜１５．０％に限定した。Ni is an element necessary to make the structure austenite, and for this purpose, it is required in an amount of 8.0% or more. However, since Ni is an expensive element, the upper limit is 8.
It was limited to 0 to 15.0%.
Ｍｏは、耐食性の中でも耐孔食性に有効な元素である。Mo is an element effective in pitting corrosion resistance among corrosion resistance.
したがって、耐孔食性が要求される場合にはＭｏを添加
するが、このＭｏが３．０％を越える場合にはσ相の析
出により脆化しやすくなるので、Ｍｏ ： ３．０％以
下と限定した。Therefore, when pitting corrosion resistance is required, Mo is added, but if this Mo exceeds 3.0%, embrittlement tends to occur due to precipitation of the σ phase, so Mo: limited to 3.0% or less. did.
次に、本発明においては、上記成分のアトマイズ粉を素
材として使用するもので、その理由について述べると、
（発明が解決しようとする課題）で述べたように、ホウ
化物は凝固時に晶出するものであり、凝固速度をあげる
ことによって細かくなる傾向にあるが、通常のインイソ
１〜鋳造や連続鋳造のプロセスでは、凝固速度をあげる
にしても限界があり、顕著なホウ化物の微細化は達成で
きない。これに対し、アトマイズ処理は、細孔から溶鋼
を流出させ、その溶鋼流に高圧の水、ガス、油等を吹き
付け、粉状に急速凝固せしめるプロセスであり、１００
℃／ｓｅｃ以上の凝固速度を容易ムこ達成することがて
きる。然してこのアＩ・マイズ処理された含ボロンオー
ステナイト系ステンレス鋼粉
一に分布していることが後述する実施例においても明ら
かにするように確認される（実施例第２表参照）。また
、アトマイズ処理は大量生産が可能なプロセスであって
、本発明では、このアトマイズ処理された含ボロンオー
ステナイト系ステンレス鋼粉を素材として使用する。即
らアトマイズ処理された粉末は、広い粒度分布をもって
いるが、ごこては、２０メッシュより細かい粉末のみを
使用することに限定した。その理由は、２ｏメンシユよ
り粗い粉末が混入していると、次工程である熱間等方圧
加圧（ＨＩＰ）および熱間押し出しにより同化する過程
で、１００％の相対密度に到達せしることが極めて困腑
なためである（例えば実施例の第１．２図参照）。Next, in the present invention, the atomized powder of the above ingredients is used as a material, and the reason is as follows.
As stated in (Problems to be Solved by the Invention), borides crystallize during solidification, and they tend to become finer as the solidification rate increases. In the process, there is a limit even if the solidification rate is increased, and significant boride refinement cannot be achieved. On the other hand, atomization is a process in which molten steel flows out through pores, and high-pressure water, gas, oil, etc. are sprayed onto the molten steel flow to rapidly solidify it into powder.
A solidification rate of .degree. C./sec or higher can be easily achieved. However, it is confirmed that the particles are distributed throughout the boron-containing austenitic stainless steel powder subjected to the atomization treatment, as will be clearly seen in the examples described later (see Table 2 of Examples). Furthermore, atomization is a process that allows mass production, and in the present invention, this atomized boron-containing austenitic stainless steel powder is used as a raw material. That is, although the atomized powder has a wide particle size distribution, the iron was limited to using only powder finer than 20 mesh. The reason is that if powder coarser than the 2O menshi is mixed in, it will reach 100% relative density during the next process of assimilation through hot isostatic pressing (HIP) and hot extrusion. This is because this is extremely difficult (see, for example, FIG. 1.2 of the embodiment).
次に、同化の方法は熱間等方圧加圧（ＨＩ Ｔ））法、
または熱間押し出しにて同化することを特徴とする。具
体的には、上記のアトマイズ処理の缶につめ、真空蜜月
した後、熱間等方圧加圧法（ＩＩＩＰ）では高圧の不活
性ガス雰囲気で加熱する。又熱間押し出しでは、型中を
熱間押し出しすることによって固化セしめ鋼片に成形す
る。また、ＨＩＰや熱間押し出しの前に、粉末を焼結や
冷間等方圧加圧（ＣＩＰ）により予備的に固化してもよ
い。このように予備固化することで、十分に充＠密度が
あがれば（〉９５％）、缶ムこ詰めずに、ＩＩ Ｉ １
）や熱間押し出しすることも可能である。何れにしても
、下記の条件で熱間等方圧加圧や熱間押し出しにより鋼
片に成形するプロセスは本発明の技術的範囲に含まれる
ものである。Next, the assimilation method is hot isostatic pressing (HIT) method,
Alternatively, it is characterized by being assimilated by hot extrusion. Specifically, the material is filled in the above-mentioned atomized can, subjected to vacuum honeycombing, and then heated in a high-pressure inert gas atmosphere in the hot isostatic pressing method (IIIP). In hot extrusion, hot extrusion is performed in a mold to form a solidified steel piece. Further, the powder may be preliminarily solidified by sintering or cold isostatic pressing (CIP) before HIP or hot extrusion. By pre-solidifying in this way, if the density is sufficiently increased (>95%), II I 1
) or hot extrusion. In any case, the process of forming a steel billet by hot isostatic pressing or hot extrusion under the following conditions is included in the technical scope of the present invention.
即ち、ＨＩ Ｐの条件として加熱温度１０００〜１２５
０℃８圧力８００ｋｇ／ｃｍ”以上に限定した理由につ
いて述べると、加熱温度が１０００℃未満、圧力８００
ｋｇ／ｃｍ２未満では、相対密度１０００
％に達せず、部分的に空隙を残した鋼片となり、次工程
の圧延時に割れが発生する（実施例における第３図参照
）。ホウ化物（（Ｆｅ、 Ｃｒ）Ｊ）の融点は１１７０
℃であり、それ以上に加熱すると部分熔融するが、ＨＩ
Ｐ処理においては多少部分溶融しても特に問題とならな
い。しかし、１２５０℃以上に加熱されると、部分溶融
後、ホウ化物（（Ｆｅ、 Ｃｒ） ２Ｂ）のマクロ的偏
析、粗大化が起こる。That is, the heating temperature is 1000-125 as the HIP condition.
The reason for limiting the temperature to 0℃8 pressure 800kg/cm" or higher is that the heating temperature is less than 1000℃ and the pressure is 800kg/cm" or higher.
If it is less than kg/cm2, the relative density will not reach 1000%, resulting in a steel piece with partial voids, and cracks will occur during rolling in the next step (see FIG. 3 in Examples). The melting point of boride ((Fe, Cr)J) is 1170
℃, and if heated above it will partially melt, but HI
In P treatment, there is no particular problem even if there is some partial melting. However, when heated to 1250° C. or higher, macroscopic segregation and coarsening of boride ((Fe, Cr) 2B) occur after partial melting.
場合によっては、缶の溶融も起こる。上記の理由から、
ＨＩ Ｐの条件を１０００〜１２５０℃加熱、８００
ｋｇ ｆ ／ｃｍ２以上の加圧に限定した（実施例にお
ける第４図など参照）。In some cases, melting of the can also occurs. For the above reasons,
HI P conditions: 1000-1250℃ heating, 800℃
The pressure was limited to kg f /cm2 or more (see FIG. 4 in Examples).
次に、熱間押し出し時の加熱条件を１０５０〜１１７０
℃に限定した理由について述べる。１０５０℃未満では
、相対密度１００％に達せず、部分的に空隙を残した鋼
片となり、次工程の圧延時に割れが発生ずる。また、１
１７０℃以上では、ホウ化物（（Ｆｅ、 Ｃｒ） ｚＢ
）が部分溶融し、完全な静水圧を付与できない押し出し
プロセスでは、缶の破裂や溶融液の滲み出しのために、
押し出し不能となる。したがって、加熱温度を１０５０
〜１１７０℃に限定した（実施例における第５図参照）
。Next, the heating conditions during hot extrusion were set to 1050 to 1170.
The reason for limiting the temperature to ℃ will be explained below. If the temperature is less than 1050°C, the relative density will not reach 100%, resulting in a steel piece with partial voids, and cracks will occur during rolling in the next step. Also, 1
At temperatures above 170°C, borides ((Fe, Cr) zB
) is partially melted and the extrusion process cannot apply full hydrostatic pressure, due to can rupture and melt oozing.
It becomes impossible to push out. Therefore, the heating temperature is 1050
~1170°C (see Figure 5 in Examples)
.
上記の方法で鋼片に成形した後、熱間圧延し、所定のサ
イズの板に仕上げる。勿論、熱間圧延時においてボウ化
物（（ＦＣ，Ｃｒ） ２Ｂ）の融点である１１７０℃以
下で圧延しなければならないことは従来法と変わらない
。しかし、ホウ化物（（Ｆｅ、 Ｃｒ） ２Ｂ）サイズ
が１μｍ以下と微細なために、熱間加工性が改善され、
割れの発生する下限温度が、大幅に緩和される（実施例
における第６図参照）。After being formed into a steel piece using the above method, it is hot rolled and finished into a plate of a predetermined size. Of course, it is no different from the conventional method that hot rolling must be carried out at a temperature below 1170° C., which is the melting point of boride ((FC, Cr) 2B). However, because the size of boride ((Fe, Cr) 2B) is as fine as 1 μm or less, hot workability is improved,
The lower limit temperature at which cracks occur is significantly relaxed (see FIG. 6 in Examples).
このプロセスで製造された含ボロンオーステナイト系ス
テンレス鋼材は、微細なボウ化物が均一・に分布してい
るため、熱中性子吸収能にも優れ、かつ常温の延性、靭
性も大幅に改善される（実施例における第３表参照）。The boron-containing austenitic stainless steel material produced by this process has fine boride particles uniformly distributed, so it has excellent thermal neutron absorption ability and has significantly improved ductility and toughness at room temperature. (See Table 3 for examples).
本発明法は、キャスク材を対象にして、開発された技術
であるが、他の用途に使用されるＢ含有Ｔ系ステンレス
鋼板においても、適用可能である。Although the method of the present invention was developed for cask materials, it is also applicable to B-containing T-series stainless steel sheets used for other purposes.
また、鋼板でなくても、形鋼や棒鋼においても、採用可
能である。さらに、本発明による鋼片、鋼１
２
材を使用すれば、他の加工方法、たとえば、鍛造、押し
出し、線引き、プレス等の加工においても、同様の熱間
加工性の向上がみられ、それにより製造された材料は、
優れた常温の延性や靭性が期待できる。In addition, it is also possible to use not only steel plates but also shaped steel and steel bars. Furthermore, if the steel billet or Steel 12 material according to the present invention is used, similar improvement in hot workability can be seen in other processing methods such as forging, extrusion, wire drawing, pressing, etc. The material manufactured by
Excellent ductility and toughness at room temperature can be expected.
（実施例）
本発明によるものの具体的な実施例について説明すると
、先ず本発明者等の採用した鋼の化学成分は次の第１表
に示す如くである。(Example) To explain specific examples of the present invention, first, the chemical composition of the steel adopted by the present inventors is as shown in Table 1 below.
即ち、Ａ−Ｆ鋼が本発明に従ったアトマイズ粉末で、水
、ガス、油によりアトマイズ処理して製造された。Ｊ（
−Ｋが、従来法である溶解−鋳造法で製造された５Ｌｏ
ｎｔｌｎ塊である（■鋼のみ、凝固速度をかえるために
、１０ｋｇインゴットにも鋳造された）。That is, A-F steel was manufactured by atomizing the atomized powder according to the present invention with water, gas, and oil. J(
-K is 5Lo manufactured by the conventional melting-casting method
ntln lump (■ Steel only, also cast in 10 kg ingots to change the solidification rate).
１ｗｔ％のＢを含有した本発明鋼と従来鋼中のホウ化物
の平均サイズを測定した結果を次の第２表に示すが、本
発明鋼中のホウ化物は、１μｍ程度で、非常に微細に分
散している。Table 2 below shows the results of measuring the average size of borides in the steel of the present invention containing 1 wt% B and the conventional steel. are distributed in
第２表
（ホウ化物の平均サイズ）
５
加熱温度とＨＩＰ後のホウ化物のサイズの関係を調べた
ものであるが、１２５０℃以上の温度でＨＩ Ｐ処理を
実施すると、ボウ化物が著しく粗大化することが、知ら
れた。第３図および第４図の結果より、ＨＩ Ｐの条件
として、加熱温度１０００〜１２５０℃、圧力８００
ｋｇ以上が適切であることが理解される。Table 2 (average size of borides) 5 The relationship between heating temperature and the size of borides after HIP was investigated, and it was found that when HIP treatment was performed at a temperature of 1250°C or higher, borides became significantly coarser. It was known that it would. From the results shown in Figures 3 and 4, the conditions for HI P are: heating temperature 1000-1250℃, pressure 800℃.
It is understood that kg or more is appropriate.
第５図は、押し出し温度と相対密度の関係を調べた結果
であって、この結果から、１０５０〜１１７０℃で押し
出しを実施しないと、真密度に到達しないことが判明し
た。FIG. 5 shows the results of examining the relationship between extrusion temperature and relative density, and it was found from this result that true density could not be reached unless extrusion was performed at 1050 to 1170°C.
上記のようにして、ＨＩＰ及び熱間押し出しの適切条イ
′１を見いだし、健全な鋼片（＝相対密度１００％）を
製造できることが可能になった。次に、それら健全な鋼
片を１１５０℃に加熱後、圧延を実施し、１５ｍｍ厚の
鋼板製造を試みた。前記第６図は、本発明鋼片と従来鋼
片を圧延した時の圧延仕−１−温度と最大耳側れ長さの
関係を示したものである。本発明鋼片では、従来鋼片に
比べ、著しく耳割れ発生開始温度が低下しており、熱間
加７
している。第１図は、本発明鋼アトマイズ粉末をふるい
により分級し、缶に詰め脱気後、ＩＩＩＰにより同化を
試み、その到達密度を調べたものであって横軸は対数目
盛であり、ここで相対密度とは次式で定義され、真密度
は７．９２ ｇ ／ｃｍ”である。As described above, it became possible to find an appropriate strip '1 for HIP and hot extrusion, and to produce a sound steel billet (=relative density 100%). Next, these sound steel pieces were heated to 1150° C. and then rolled to attempt to manufacture a 15 mm thick steel plate. FIG. 6 shows the relationship between the rolling finish-1 temperature and the maximum edge side deviation length when the steel billet of the present invention and the conventional steel billet were rolled. In the steel billet of the present invention, the temperature at which edge cracking starts is significantly lower than that of the conventional steel billet, and the steel billet is hot-heated. In Figure 1, the atomized steel powder of the present invention was classified using a sieve, packed in a can, deaerated, and then assimilated by IIIP, and the achieved density was investigated.The horizontal axis is a logarithmic scale, where the relative Density is defined by the following formula, and the true density is 7.92 g/cm''.
相対密度−固化した後の試料密度／真密度即ち２０メッ
シュより細かい粉末のみでＨＩ Ｐすると、相対密度１
００％に到達することが可能であることが確認された（
相対密度−固化処理後の密度／真密度）。第２図は、同
しごとを熱間押し出しで調べた結果を示しているもので
横軸は同じく対数目盛である。熱間押し出しは、丸ビレ
ットをくりぬき、粉末を充填し脱気した缶を埋め込んで
実施した。熱間押し出しで固化する場合も、２０メッシ
ュより細かい粉末のみであれば、真密度に到達すること
が可能である。Relative Density - Sample Density after Solidification/True Density, i.e., if you HI P only with powder finer than 20 mesh, the relative density is 1
It was confirmed that it is possible to reach 00% (
Relative density - density after solidification/true density). FIG. 2 shows the results of a hot extrusion study of the same thing, and the horizontal axis is also on a logarithmic scale. Hot extrusion was carried out by hollowing out a round billet and embedding a can filled with powder and degassed. Even when solidifying by hot extrusion, it is possible to reach true density if only powder is finer than 20 mesh.
第３図は、ＨＩ Ｐ条件と相対密度の関係を調べたもの
であって、加熱温度１０００℃未満、１力８００ ｋｇ
ｆ ／ｗｓｓ２未満の条件では、真密度に到達しないこ
とが判明した。また第４図は、ＩＩ Ｉ Ｐの６
工性が改善されていることが理解される。Figure 3 shows the relationship between HIP conditions and relative density.
It was found that the true density was not reached under conditions of less than f/wss2. Furthermore, it can be seen from FIG. 4 that the workability of II I P has been improved.
次の第３表は、本発明法及び従来法で製造された１５ｍ
ｍ厚の鋼板の常温の機械的性質を示したものである。従
来法と本発明法で製造された同量のＢを含有した鋼板の
伸び値及びシャルピー衝撃吸収エネルギー値を比較する
と、本発明鋼板の方が著しく高い値を示している。また
、強度も本発明鋼板の方が、高い値を示している。The following Table 3 shows the 15m manufactured by the method of the present invention and the conventional method.
This figure shows the mechanical properties of a steel plate of m thickness at room temperature. Comparing the elongation values and Charpy impact absorption energy values of steel plates containing the same amount of B produced by the conventional method and the method of the present invention, the steel plates of the present invention exhibit significantly higher values. In addition, the steel sheet of the present invention exhibits a higher strength value.
８
第 ３ 表
（発明鋼板及び従来鋼板の常温の強度・延性・靭慟■
れる）のに対し、本発明鋼板では、粉末を素材としてい
るために、マクロ的な偏析は皆無である。また、本発明
鋼板では、ホウ化物が、著しく微細に分布しているため
、ミクロ的にも、均一に分布していることになり、中性
子遮蔽効果の向上がもたらされる。8 Table 3 (Strength, ductility, and toughness at room temperature of the invented steel sheet and the conventional steel sheet) In contrast, the steel sheet of the present invention has no macroscopic segregation because it is made of powder. Further, in the steel sheet of the present invention, since the borides are extremely finely distributed, the borides are evenly distributed microscopically, resulting in an improvement in the neutron shielding effect.
図面は本発明の技術的内容を示すものであって、第１図
は本発明のＨＩＰ処理における使用粉末（アンダーメソ
シュで表示）と到達相対密度（同化後の試料密度／真密
度）の関係を示した図表、第２図は本発明の熱間押し出
し処理における使用粉末（アンダーメソシュで表示）と
到達相対密度の関係を示した図表、第３図は本発明のＨ
ＩＰ条件（温度、圧力）と到達相対密度の関係を示した
図表、第４図は本発明のＨＩＰ加熱温度とＨＩＰ後のホ
ウ化物のサイズの関係について示した図表、第５図は本
発明の押し出し加工温度と到達相対密度の関係を示した
図表、第６図は本発明法により製造された鋼片と従来法
により製造された鋼片を１
「発明の効果Ｊ
以上説明したような、本発明によれば、熱間加工性、常
温の延性、靭性に優れた使用済み核燃料キャスク用Ｂ含
有γ系ステンレス鋼板が製造でき、従って、次のような
効果が得られ工業的にその効果の大きい発明である。
■ 鋼板製造メーカーにおいては、圧延可能温度が広が
り、製造が容易になる。従来は、何度も加熱−圧延を繰
返していたがその回数が著しく低減でき、圧延のコスト
、能率が著しく改善できる。また、従来法では、耳割れ
のために、切り捨て部が多かったが、本発明によれば、
著しく低減できる。
■ キャスクの組み立てメーカーにおいては、常温の延
性・靭性が向上したため、強加工が可能となり、設計、
組み立てが容易になる。
■ キャスクの使用者においては、常温の延性・靭性が
向上したため、安全性が高まる。
■ 従来鋼板では、その製造方法に由来し、鋼板中にＢ
のマクロ的偏析がある（鋳造時に形成さ０
圧延した時、圧延仕上温度と最大耳側れ長さの関係を示
した図表である。The drawings show the technical content of the present invention, and Figure 1 shows the relationship between the powder used in the HIP process of the present invention (indicated by under mesh) and the achieved relative density (sample density after assimilation/true density). Figure 2 is a diagram showing the relationship between the powder used in the hot extrusion process of the present invention (expressed in undermethods) and the achieved relative density, and Figure 3 is a diagram showing the relationship between the H
Figure 4 is a diagram showing the relationship between IP conditions (temperature, pressure) and achieved relative density. Figure 4 is a diagram showing the relationship between the HIP heating temperature of the present invention and the size of boride after HIP. Figure 5 is a diagram showing the relationship between the HIP heating temperature and the size of the boride after HIP. Figure 6, a diagram showing the relationship between extrusion temperature and achieved relative density, shows the relationship between the steel billet manufactured by the method of the present invention and the steel billet manufactured by the conventional method. According to the invention, it is possible to produce a B-containing γ-stainless steel plate for spent nuclear fuel casks that has excellent hot workability, room temperature ductility, and toughness, and therefore has the following effects, which are industrially significant. This is an invention. ■ For steel plate manufacturers, the rolling temperature range is expanded, making production easier. Conventionally, heating and rolling were repeated many times, but the number of times can be significantly reduced, reducing rolling costs and efficiency. This can be significantly improved.In addition, in the conventional method, there were many cut-off parts due to the cracked edges, but according to the present invention,
It can be significantly reduced. ■ For cask assemblers, improvements in ductility and toughness at room temperature have enabled strong machining, making design,
Easy to assemble. ■ For cask users, safety is improved due to improved ductility and toughness at room temperature. ■ Conventional steel sheets contain B due to their manufacturing method.
There is macro segregation (formed during casting). This is a chart showing the relationship between finishing rolling temperature and maximum edge side length when rolling.
Claims (1)
以下、Ｓｉ：０．０１〜２．０％、Ｍｎ：２．０％以下
、Ｃｒ：１６．０〜２０．０％、Ｎｉ：８．０〜１５．
０％、Ｍｏ：３．０％以下を含有し、残部が鉄および不
可避的不純物よりなる２０メッシュより細かいアトマイ
ズ粉末を、加熱温度１０００〜１２５０℃、圧力８００
ｋｇ／ｃｍ＾２以上の条件で熱間等方圧加圧により鋼片
に成形した後、熱間圧延することを特徴とする、熱間加
工性および常温の延性、靭性に優れた含ボロンオーステ
ナイト系ステンレス鋼材の製造方法。 ２、重量％で、Ｂ：０．３〜３．０％、Ｃ：０．０８％
以下、Ｓｉ：０．０１〜２．０％、Ｍｎ：２．０％以下
、Ｃｒ：１６．０〜２０．０％、Ｎｉ：８．０〜１５．
０％、Ｍｏ：３．０％以下を含有し、残部が鉄および不
可避的不純物よりなる２０メッシュより細かいアトマイ
ズ粉末を、１０５０〜１１７０℃の温度範囲で熱間押出
しにて鋼片に成形した後、熱間圧延することを特徴とす
る、熱間加工性および常温の延性、靭性に優れた含ボロ
ンオーステナイト系ステンレス鋼材の製造方法。[Claims] 1. In weight%, B: 0.3 to 3.0%, C: 0.08%
Below, Si: 0.01-2.0%, Mn: 2.0% or less, Cr: 16.0-20.0%, Ni: 8.0-15.
0%, Mo: 3.0% or less, and the balance is iron and inevitable impurities.
Boron-containing austenite with excellent hot workability, ductility and toughness at room temperature, characterized by being formed into a steel billet by hot isostatic pressing under conditions of kg/cm^2 or more and then hot rolling. A method for manufacturing stainless steel materials. 2. In weight%, B: 0.3-3.0%, C: 0.08%
Below, Si: 0.01-2.0%, Mn: 2.0% or less, Cr: 16.0-20.0%, Ni: 8.0-15.
After forming an atomized powder finer than 20 mesh containing 0%, Mo: 3.0% or less, and the remainder consisting of iron and unavoidable impurities into a steel billet by hot extrusion at a temperature range of 1050 to 1170°C. A method for producing a boron-containing austenitic stainless steel material having excellent hot workability, ductility and toughness at room temperature, the method comprising hot rolling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18243189A JPH0347946A (en) | 1989-07-17 | 1989-07-17 | Manufacture of boron-containing austenitic stainless steel having excellent hot workability as well as cold ductility and toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18243189A JPH0347946A (en) | 1989-07-17 | 1989-07-17 | Manufacture of boron-containing austenitic stainless steel having excellent hot workability as well as cold ductility and toughness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0347946A true JPH0347946A (en) | 1991-02-28 |
Family
ID=16118152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18243189A Pending JPH0347946A (en) | 1989-07-17 | 1989-07-17 | Manufacture of boron-containing austenitic stainless steel having excellent hot workability as well as cold ductility and toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0347946A (en) |
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| EP0789086A3 (en) * | 1996-01-30 | 1998-01-07 | Framatome | Process for preparing a metallic material having high hardness and its use |
| WO1998038725A1 (en) * | 1997-02-26 | 1998-09-03 | Seiko Instruments Inc. | Stepper motor |
| CN101985678A (en) * | 2010-12-03 | 2011-03-16 | 西安诺博尔稀贵金属材料有限公司 | Method for preparing austenitic stainless steel tube blank for nuclear power |
| CN105463293A (en) * | 2015-12-02 | 2016-04-06 | 中国核动力研究设计院 | Preparing method of structural shield integration board made of high-boron stainless steel |
| CN105499582A (en) * | 2015-12-08 | 2016-04-20 | 中国核动力研究设计院 | Preparation method of high-boron boronated stainless steel |
| CN106392077A (en) * | 2016-10-09 | 2017-02-15 | 中国核动力研究设计院 | Preparation method for high-boron stainless steel plate |
-
1989
- 1989-07-17 JP JP18243189A patent/JPH0347946A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0789086A3 (en) * | 1996-01-30 | 1998-01-07 | Framatome | Process for preparing a metallic material having high hardness and its use |
| WO1998038725A1 (en) * | 1997-02-26 | 1998-09-03 | Seiko Instruments Inc. | Stepper motor |
| CN101985678A (en) * | 2010-12-03 | 2011-03-16 | 西安诺博尔稀贵金属材料有限公司 | Method for preparing austenitic stainless steel tube blank for nuclear power |
| CN105463293A (en) * | 2015-12-02 | 2016-04-06 | 中国核动力研究设计院 | Preparing method of structural shield integration board made of high-boron stainless steel |
| CN105463293B (en) * | 2015-12-02 | 2018-03-06 | 中国核动力研究设计院 | The preparation method for the structual shield integrated plate that high boron stainless steel is formed |
| CN105499582A (en) * | 2015-12-08 | 2016-04-20 | 中国核动力研究设计院 | Preparation method of high-boron boronated stainless steel |
| CN106392077A (en) * | 2016-10-09 | 2017-02-15 | 中国核动力研究设计院 | Preparation method for high-boron stainless steel plate |
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