JPS6411082B2 - - Google Patents
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- Publication number
- JPS6411082B2 JPS6411082B2 JP4146485A JP4146485A JPS6411082B2 JP S6411082 B2 JPS6411082 B2 JP S6411082B2 JP 4146485 A JP4146485 A JP 4146485A JP 4146485 A JP4146485 A JP 4146485A JP S6411082 B2 JPS6411082 B2 JP S6411082B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- stainless steel
- austenitic stainless
- cracks
- ingot
- 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
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 28
- 239000010959 steel Substances 0.000 claims description 28
- 229910000963 austenitic stainless steel Inorganic materials 0.000 claims description 22
- 238000005098 hot rolling Methods 0.000 claims description 16
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000005096 rolling process Methods 0.000 claims description 7
- 238000005242 forging Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000007493 shaping process Methods 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 30
- 239000000463 material Substances 0.000 description 22
- 229910052742 iron Inorganic materials 0.000 description 15
- 229910001220 stainless steel Inorganic materials 0.000 description 9
- 238000005260 corrosion Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 239000010935 stainless steel Substances 0.000 description 6
- 239000003758 nuclear fuel Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000005266 casting Methods 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000002915 spent fuel radioactive waste Substances 0.000 description 3
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 150000002505 iron Chemical class 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000009497 press forging Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
利用産業分野
この発明は、核燃料集合体輸送用容器、核燃料
保管用ラツク及び使用済み核燃料保管用ラツク等
に用いられるB0.5wt％〜3.0wt％含有のCr15wt％
〜21wt％、Ni7.0wt％〜16wt％系オーステナイ
トステンレス鋼の製造方法に係り、特に、熱間圧
延性の改善を目的としたＢ含有オーステナイトス
テンレス鋼の製造方法に関する。
背景技術
一般に、Ｂ含有のオーステナイトステンレス鋼
は、含有するＢの中性子吸収断面積が大きいこと
より、中性子の制御材及び遮蔽材として用いられ
ている。
特に、高Ｂ含有オーステナイトステンレス鋼
は、核燃料集合体輸送用容器、核燃料保管用ラツ
ク及び使用済み核燃料保管用ラツク等に用いられ
ているが、今日、該容器やラツクの小形化と低コ
スト化のために、素材である該ステンレス鋼の薄
肉化が要望されている。
しかし、Ｂ含有のオーステナイトステンレス鋼
は、Ｂ含有量が多くなると、Ｂがステンレス鋼に
固溶せず、硼化物が析出し、これが脆い性質を有
するため、熱間加工時に割れやすく、また一旦割
れが発生すると、次々に硼化物により割れが伝播
していき、割れが少なく加工できる熱間加工温度
領域が狭く、難加工材となり、熱間圧延時に圧延
材の表面、特に冷却され易く引張力の掛る長手方
向の縁部に、割れやひび疵などが発生し易くな
り、後工程での加工などが不可能となり、製品化
できず歩留が悪い問題があつた。
このため、Ｂ含有のオーステナイトステンレス
鋼の熱間圧延性改善について、種々検討されてお
り、鋼材，Fe―Ni合金あるいはTi材の熱間圧延
において、前記素材の外周全面を薄鉄板で被包し
て熱間圧延したり（特開昭56―38418号）、有孔異
種金属板で被包して熱間圧延する技術（特開昭54
―6842号）が知られているが、これは酸化防止及
び焼付き防止のためであり、本発明鋼のごとき硼
化物とオーステナイト相との２相よりなる合金の
難加工性を改善するのではなく、また、有孔異種
金属板を用いる場合は、素材と被包材間の空気抜
き孔のために逆に酸化が進行し、熱間圧延時に被
包金属板が素材より剥離する恐れがあつた。
発明の目的
この発明は、Ｂ含有のオーステナイトステンレ
ス鋼の熱間加工性の改善を目的とし、熱間加工時
に加工材の長手方向縁部に割れやひび疵が発生す
るのを防止し、後続工程の加工を容易にし、製品
歩留の大幅な向上が得られるＢ含有オーステナイ
トステンレス鋼の製造方法を目的としている。
発明の構成
この発明は、B0.5wt％〜3.0wt％含有のCr15wt
％〜21wt％、Ni7.0wt％〜16wt％系オーステナ
イトステンレス鋼の溶鋼を、鋳型内に嵌入した鉄
筒内に注入し、外周面に鉄筒を溶着した鋳塊に造
塊し、
前記鋼塊を950℃〜1250℃で分塊圧延あるいは
鍛造し、整形後、
950℃〜1250℃に加熱し、１パス当りの圧下率
10％〜70％で、少なくとも１回の熱間圧延を行な
うことを特徴とするＢ含有オーステナイトステン
レス鋼の製造方法である。
さらに、詳述すれば、この発明は、
ａ B0.5wt％〜3.0wt％含有のCr15wt％〜21wt
％、Ni7.0wt％〜16wt％系オーステナイトステ
ンレス鋼の溶鋼を、
ｂ 例えば、鋳型内の内壁に密着させて嵌入し
た、炭素鋼あるいはステンレス鋼からなる鉄筒
内に鋳込み、
ｃ 得られた鋼塊のすくなくとも４主面、すなわ
ち、長手方向の両端面を除く外周面の４主面に
炭素鋼やステンレス鋼からなる鉄筒を溶着した
鋼塊に造塊し、
ｄ 上記鋼塊を950℃〜1250℃にて分塊圧延ある
いは鍛造し、整形した後、
ｅ 950℃〜1250℃に加熱し、１パス当りの圧下
率10％〜70％で、少なくとも１回の熱間圧延を
行なつたのち、
ｆ そのままか、あるいは溶体化処理を施し、必
要に応じて冷間圧延もしくはレベラーにより平
坦度を矯正し、
ｇ その後熱間圧延材の外周面最外層の鉄層を除
去し、必要に応じて冷間圧延もしくはレベラー
により平坦度を矯正し、
熱間圧延時に圧延材の長手方向縁部に割れやひ
び疵のない品質良好な高Ｂ含有オーステナイトス
テンレス鋼を得る製造方法である。
この発明において、上記ｂの鉄筒は、パイプ状
や板材による溶接組立体などが利用でき、鉄筒内
に溶湯の鋳込みが可能であればよく、鋳込時、下
面に有底の容器でもよい。また、溶着を十分確保
するため、鋳込時鋳型内雰囲気は非酸化性雰囲気
が好ましく、真空中鋳込やAr雰囲気鋳込がより
効果的である。なお、長手両端面について、鉄筒
と鋼塊とを溶接することは、熱間加工中の端面よ
りの鉄筒の剥離を防止するのに有効である。
また、鉄筒の材質は、熱間変形抵抗を一致させ
るためステンレス鋼を用いるのもよいが、コスト
面からは軟鋼が好ましく、鉄筒の厚みは、熱間圧
延終了まで残存する程度の厚みが必要で、好まし
くは５mm〜10mm厚みである。
発明の効果
この発明の製造方法により、熱間加工性が大幅
に改善され、熱間加工時に加工材の長手方向縁部
に割れやひび疵のない品質良好な高Ｂ含有オース
テナイト系ステンレス鋼が得られるが、その理由
は、熱間圧延時のロール接触あるいは冷却水及び
周囲温度の影響により、加工材、特に縁部の温度
が低下するとともに加工時の種々の引張力がかか
り、上述の所謂耳われ等を生じるが、この発明鋼
は、硼化物とオーステナイト相との２相からな
り、温度低下や引張力がかかり、割れやひび疵な
どが一旦発生すると、硼化物により次々と割れや
ひび疵が伝播進行し、製品化できなくなるので、
特に初期に割れやひび疵を発生させないことか重
要であり、この発明方法では鋼塊表面に密着させ
た鉄筒によつて上記の温度低下が防止され、ま
た、長手方向の縁部に掛りやすい加工時の引張力
が、前記の良好な高温変形能を有する鉄筒により
緩和されるためである。
この発明の製造方法の効果は、熱間圧延のみな
らず、分塊圧延あるいは鍛造時にも同様に有効で
あり、鍛造はハンマー鍛造，プレス鍛造のいずれ
でも有効である。また、造塊時に鉄筒と溶着する
ため、密着しやすく、十分な保護作用の効果が得
られる。
発明の限定理由
この発明においてオーステナイトステンレス鋼
の成分限定理由は、以下のとおりである。
Ｂは、中性子の吸収効果を有するために含有す
るが、0.5wt％未満では、中性子吸収効果が少な
く、制御材，遮蔽材としての板厚が大きくなり、
前述の容器やラツクが大型化しコスト高となるた
め好ましくなく、また、3.0wt％を超ある含有で
は材料の延び及び衝撃値が著しく劣化して構造材
として不適となるため、0.5wt％〜3.0wt％の範囲
とする。
Crは、本系においてNiと共に耐食性を得るた
めに含有するが、15wt％未満では、充分な耐食
性が得られず、Crの含有量の増加と共に耐食性
は良好となるが、21wt％を超える含有ではその
効果が飽和し、コスト面で好ましくないため、
15wt％〜21wt％の範囲とする。
Niは、本系においてCrと共に耐食性を得るた
めに含有するが、7.0wt％未満では、還元性雰囲
気にて充分な耐食性が得られず、また、16wt％
を超える含有ではその効果が飽和し、コスト面で
好ましくないため、7.0〜16wt％の範囲とする。
この発明において、好ましいＢ含有オーステナ
イトステンレス鋼は、
B0.5wt％〜3.0wt％、
C0.12twt％以下、Si1.0wt％以下、Mn2.0wt％
以下、
P0.05wt％以下、S0.03wt％以下、
Cr15wt％〜21wt％、Ni7.0wt％〜16wt％
残部実質的にFeからなるオーステナイトステ
ンレス鋼である。
Ｃは、0.12wt％を超えると粒界に炭化物を生成
し易くなり、粒界腐蝕を起し易くなり好ましくな
いため、0.12wt％以下とする。
Siは、耐酸化性及び溶接性の改善に有効である
が、1.0wt％を超える含有はその効果が飽和して
コスト的に好ましくないため、1.0wt％以下とす
る。
Mnは、高温での耐酸化性が得られるが、
2.0wt％を超えると反つて低下するため、2.0wt％
％以下とする。
Ｐ，Ｓは、応力腐蝕割れを招来するので、
P0.05wt％以下、S0.03wt％以下とする必要があ
る。
本系ステンレス鋼において、残部は、Feと不
可避的不純物である。
また、この発明方法において、分塊圧延，鍛造
並びに熱間圧延の温度を950℃〜1250℃としたの
は、950℃未満では、成形鋼塊の変形抵抗が大き
く、変形能が低下し、われ疵などを発生するため
好ましくなく、また、1250℃を超えると、結晶粒
の粗大化が起り、われ発生を惹起するためであ
る。
また、１パス当りの圧下率を10％〜70％とした
のは、10％未満では硼化物の充分な微細分散化を
計ることができず、また、70％を超えると加工度
が大きくなりすぎ、われまたはひび疵が発生し易
くなるためである。
実施例
実施例 １
B2.1wt％、C0.03wt％、
Si0.52wt％、Mn1.42wt％、
Cr17.9wt％、Ni12.1wt％
P0.011wt％、S0.005wt％、
残部実質的にFe
からなるオーステナイトステンレス鋼の溶鋼を、
内寸上辺176mm×横356mm，下辺縦136mm×横356
mm、高さ770mm、鋳型厚み80mmの鋳型内に、内寸
上辺160mm×横340mm，下辺縦120mm×横340mm、高
さ770mm、板厚み８mm寸法，C0.10％の軟鋼からな
る鉄筒を嵌入し、この鉄筒内にArガス雰囲気で
鋳込し、外周面に厚さ８mmの鉄筒を溶着した290
Kgの鋼塊に造塊した。
この鋼塊を1230℃に加熱し、１パス当りの圧下
率10〜70％範囲内のプレス鍛造を施し、厚さ65mm
×幅335mm×長さ1945mm寸法の熱間圧延素材に整
形した。
その後、1230℃に加熱し、１パス当りの圧下率
54％，33％，25％，33％，30％の熱間圧延を行な
い、５パスで板厚７mm×幅350mm×長さ17300mm寸
法の板材となした。
熱間圧延後に長手方向に４分割し、1050℃，１
時間の熱処理を行ない、水冷し、板材の外表面の
軟鉄層部分を切削除去し、レベラーにより平坦度
を矯正し、最終仕上寸法として、板厚６mm×幅
330mm×長さ4300mm寸法の板材となした。
また、比較例として、上記組成のオーステナイ
トステンレス鋼をそのまま鍛造及び熱間圧延し、
同様の最終仕上寸法となした。
得られた２種のオーステナイトステンレス熱間
圧延材の加工における各々の加熱回数と耳割れ状
況及び製品歩留（最終製品／鋼塊×100％）を調
べ、第１表にその結果を示す。
Field of Application This invention is applicable to containers for transporting nuclear fuel assemblies, racks for storing nuclear fuel, racks for storing spent nuclear fuel, etc. containing Cr15wt% containing B0.5wt% to 3.0wt%.
The present invention relates to a method for producing austenitic stainless steel containing ~21wt% Ni and 7.0wt% to 16wt% Ni, and particularly relates to a method for manufacturing a B-containing austenitic stainless steel for the purpose of improving hot rolling properties. BACKGROUND ART In general, B-containing austenitic stainless steels are used as neutron control and shielding materials because the B they contain has a large neutron absorption cross section. In particular, high B-containing austenitic stainless steel is used for containers for transporting nuclear fuel assemblies, racks for storing nuclear fuel, racks for storing spent nuclear fuel, etc., and today, these containers and racks are becoming smaller and lower in cost. Therefore, there is a demand for thinner stainless steel material. However, when B-containing austenitic stainless steel has a high B content, B does not dissolve in solid solution in the stainless steel and borides precipitate, which has brittle properties and is prone to cracking during hot working. When this occurs, cracks propagate one after another due to the borides, and the hot working temperature range that can be processed with few cracks is narrow, making the material difficult to work. Cracks and cracks are likely to occur on the longitudinal edges, making it impossible to process in post-processes, resulting in a problem of poor product yield. For this reason, various studies have been conducted to improve the hot rolling properties of B-containing austenitic stainless steels, and in the hot rolling of steel materials, Fe-Ni alloys, or Ti materials, the entire outer periphery of the material is covered with a thin iron plate. (Japanese Unexamined Patent Publication No. 56-38418), or encased in a perforated dissimilar metal plate and hot rolled (Japanese Unexamined Patent Publication No. 54-1983).
-6842), but this is to prevent oxidation and seizure, and may improve the difficult-to-work properties of alloys consisting of two phases of boride and austenite phases, such as the steel of the present invention. Furthermore, when a perforated dissimilar metal plate is used, oxidation progresses due to the air vent holes between the raw material and the encasing material, and there is a risk that the encasing metal plate may separate from the material during hot rolling. . Purpose of the Invention The present invention aims to improve the hot workability of B-containing austenitic stainless steel, to prevent cracks and cracks from occurring on the longitudinal edges of the workpiece during hot working, and to prevent cracks from occurring in the longitudinal edges of the workpiece during hot working. The purpose of the present invention is to provide a method for producing B-containing austenitic stainless steel that facilitates processing and significantly improves product yield. Structure of the Invention The present invention provides Cr15wt containing B0.5wt% to 3.0wt%.
% ~ 21 wt%, Ni 7.0 wt% ~ 16 wt% molten austenitic stainless steel is injected into a steel cylinder fitted in a mold, and an ingot with a steel cylinder welded to the outer circumferential surface is formed into an ingot. The material is bloomed or forged at 950°C to 1250°C, and after shaping, heated to 950°C to 1250°C, reducing the rolling reduction rate per pass.
This is a method for producing a B-containing austenitic stainless steel, characterized in that hot rolling is carried out at least once at a B content of 10% to 70%. Further, in detail, the present invention provides the following methods: a B0.5wt% to 3.0wt% containing Cr15wt% to 21wt
%, Ni7.0wt% to 16wt% austenitic stainless steel is cast into a steel cylinder made of carbon steel or stainless steel, for example, which is fitted tightly against the inner wall of the mold, and c. the obtained steel ingot. A steel ingot made of carbon steel or stainless steel is welded to at least four principal surfaces, i.e., the four principal surfaces of the outer peripheral surface excluding both end surfaces in the longitudinal direction, and the above steel ingot is heated at 950℃ to 1250℃. After blooming or forging at °C and shaping, e heating to 950 °C to 1250 °C and hot rolling at least once at a rolling reduction rate of 10% to 70% per pass, f Leave it as it is or apply solution treatment and correct the flatness using cold rolling or a leveler if necessary; g Then remove the outermost iron layer on the outer peripheral surface of the hot rolled material and cool it if necessary. This is a production method that corrects the flatness using inter-rolling or a leveler, and obtains high-quality austenitic stainless steel containing high B content without cracks or cracks on the longitudinal edges of the rolled material during hot rolling. In this invention, the iron cylinder described in b above can be a pipe-shaped or a welded assembly made of plate materials, and it is sufficient that molten metal can be poured into the iron cylinder, and it may be a container with a bottom at the bottom during casting. . In order to ensure sufficient welding, the atmosphere inside the mold during casting is preferably a non-oxidizing atmosphere, and vacuum casting or Ar atmosphere casting is more effective. Note that welding the steel tube and the steel ingot on both longitudinal end surfaces is effective in preventing the steel tube from peeling off from the end surfaces during hot working. In addition, stainless steel may be used as the material for the steel tube in order to match hot deformation resistance, but mild steel is preferable from a cost perspective, and the thickness of the steel tube should be such that it remains until the end of hot rolling. The thickness is preferably 5 mm to 10 mm. Effects of the Invention The production method of the present invention significantly improves hot workability and provides high-quality, high-B-containing austenitic stainless steel with no cracks or cracks on the longitudinal edges of the workpiece during hot working. The reason for this is that the temperature of the workpiece, especially the edges, decreases due to roll contact during hot rolling or the effects of cooling water and ambient temperature, and various tensile forces are applied during processing, resulting in the so-called ear However, this invented steel consists of two phases: boride and austenite, and once cracks and cracks occur due to temperature drop and tensile force, the boride causes cracks and cracks to occur one after another. will continue to spread and will not be able to be commercialized.
It is especially important to prevent cracks and cracks from occurring in the initial stage, and in this invention method, the above temperature drop is prevented by the iron cylinder that is tightly attached to the surface of the steel ingot, and it is also easy to prevent cracks from forming on the edges in the longitudinal direction. This is because the tensile force during processing is alleviated by the iron tube having the above-mentioned good high-temperature deformability. The manufacturing method of the present invention is effective not only during hot rolling but also during blooming rolling or forging, and is effective whether the forging is hammer forging or press forging. In addition, since it is welded to the steel tube during ingot making, it is easy to adhere to it and provides sufficient protection. Reasons for limiting the invention The reasons for limiting the components of the austenitic stainless steel in this invention are as follows. B is contained because it has a neutron absorption effect, but if it is less than 0.5wt%, the neutron absorption effect is small and the plate thickness as a control material and shielding material becomes large.
It is undesirable because the containers and racks mentioned above become large and costly, and if the content exceeds 3.0wt%, the elongation and impact value of the material will deteriorate significantly, making it unsuitable as a structural material. The range is wt%. Cr is contained in this system together with Ni to obtain corrosion resistance, but if it is less than 15wt%, sufficient corrosion resistance cannot be obtained.As the Cr content increases, corrosion resistance improves, but if the content exceeds 21wt%, Since the effect has saturated and it is not favorable from a cost perspective,
The range is 15wt% to 21wt%. Ni is contained in this system together with Cr to obtain corrosion resistance, but if it is less than 7.0wt%, sufficient corrosion resistance cannot be obtained in a reducing atmosphere, and if it is less than 7.0wt%, sufficient corrosion resistance cannot be obtained in a reducing atmosphere.
If the content exceeds 10%, the effect will be saturated and it will be unfavorable in terms of cost, so the content should be in the range of 7.0 to 16wt%. In this invention, preferable B-containing austenitic stainless steels include B0.5wt% to 3.0wt%, C0.12wt% or less, Si1.0wt% or less, Mn2.0wt%
Below, P0.05wt% or less, S0.03wt% or less, Cr15wt% ~ 21wt%, Ni 7.0wt% ~ 16wt%, and the balance is an austenitic stainless steel consisting essentially of Fe. If C exceeds 0.12 wt%, carbides tend to form at grain boundaries, which tends to cause intergranular corrosion, which is undesirable, so it is set to 0.12 wt% or less. Si is effective in improving oxidation resistance and weldability, but if the content exceeds 1.0 wt%, the effect will become saturated and this is not desirable in terms of cost, so the content should be 1.0 wt% or less. Mn provides oxidation resistance at high temperatures, but
If it exceeds 2.0wt%, it will warp and decrease, so 2.0wt%
% or less. P and S cause stress corrosion cracking, so
It is necessary to keep P0.05wt% or less and S0.03wt% or less. In this stainless steel, the remainder is Fe and unavoidable impurities. In addition, in the method of this invention, the temperature of blooming, forging, and hot rolling is set at 950°C to 1250°C, because if the temperature is less than 950°C, the deformation resistance of the formed steel ingot will be large and the deformability will decrease. This is undesirable because it may cause scratches, and if the temperature exceeds 1250°C, the crystal grains will become coarser, causing cracks. In addition, the reduction rate per pass was set at 10% to 70% because if it is less than 10%, sufficient fine dispersion of the boride cannot be achieved, and if it exceeds 70%, the degree of processing becomes large. This is because scratches, cracks, and cracks are more likely to occur. ExamplesExample 1 B2.1wt%, C0.03wt%, Si0.52wt%, Mn1.42wt%, Cr17.9wt%, Ni12.1wt% P0.011wt%, S0.005wt%, balance essentially made of Fe The molten steel of austenitic stainless steel becomes
Inner dimensions: Top side 176mm x width 356mm, bottom side length 136mm x width 356mm
Into a mold with a height of 770 mm and a mold thickness of 80 mm, an iron cylinder made of mild steel with C0.10% is inserted, with inner dimensions of top side 160 mm x width 340 mm, bottom side length 120 mm x width 340 mm, height 770 mm, plate thickness 8 mm. 290 was cast into this iron cylinder in an Ar gas atmosphere, and an 8 mm thick iron cylinder was welded to the outer circumferential surface.
It was made into a steel ingot of kg. This steel ingot was heated to 1230℃ and press forged with a reduction rate of 10 to 70% per pass to a thickness of 65 mm.
It was shaped into a hot rolled material with dimensions of x width 335mm x length 1945mm. After that, it is heated to 1230℃, and the rolling reduction rate per pass is
Hot rolling was performed at 54%, 33%, 25%, 33%, and 30%, and a plate material with dimensions of 7 mm thick x 350 mm wide x 17,300 mm long was obtained in 5 passes. After hot rolling, it was divided into four parts in the longitudinal direction and heated at 1050°C for 1
Heat treatment is performed for several hours, water-cooled, the soft iron layer on the outer surface of the plate is removed, the flatness is corrected using a leveler, and the final finished dimensions are 6 mm thick x width.
It was made into a board with dimensions of 330mm x length 4300mm. In addition, as a comparative example, austenitic stainless steel with the above composition was forged and hot rolled as it was,
The final dimensions were the same. The number of heating times, edge cracking, and product yield (final product/steel ingot x 100%) during processing of the two types of hot-rolled austenitic stainless steel materials obtained were investigated, and the results are shown in Table 1.
【表】
実施例 ２
B1.9wt％、C0.006wt％、
Si0.69wt％、Mn1.78wt％、
Cr19.4wt％、Ni11.3wt％、
P0.023wt％、S0.008wt％、
残部実質的にFe
からなるオーステナイトステンレス鋼の溶鋼を、
内寸上辺172mm×横284mm，下辺縦129mm×横279
mm、高さ577mm、鋳型厚み80mmの鋳型内に、内寸
上辺158mm×横270mm，下辺縦114mm×横265mm、高
さ570mm、板厚み７mm寸法，C0.18％の軟鋼からな
る鉄筒を嵌入し、この底付き鉄筒内に真空雰囲気
で鋳込し、外周面に厚さ７mmの鉄皮を溶着した
170Kgの鋼塊に造塊した。
この鋼塊を1220℃に加熱し、１パス当りの圧下
率10〜60％範囲内のハンマー鍛造を施し、厚さ50
mm×幅260mm×長さ1850mm寸法の圧延素材に整形
した。
その後、1210℃に加熱し、１パス当りの圧下率
50％，32％，29％，25％，28％，23％の熱間圧延
を行ない、６パスで板厚５mm×幅280mm×長さ
17410mm寸法の板材となした。
熱間圧延後に長手方向に４分割し、1050℃，
0.5時間の軟化処理を行ない、水冷し、板材の外
表面の軟鉄層部分を切削除去し、レベラーにより
平坦度を矯正し、最終仕上寸法として、板厚４mm
×幅260mm×長さ4300mm寸法の板材となした。
また、比較例として、上記組成のオーステナイ
トステンレス鋼をそのまま鍛造及び熱間圧延し、
同様の板厚４mm×幅260mm×長さ4300mmの最終仕
上寸法となした。
得られた２種のオーステナイトステンレス熱間
圧延材の加工における各々の加熱回数と耳割れ状
況及び製品歩留（最終製品／鋼塊×100％）を調
べ、第２表にその結果を示す。
第１表，第２表の結果より明らかな如く、この
発明の製造方法によつて、難加工性である高Ｂ含
有オーステナイトステンレス鋼の熱間圧延性が大
幅に改善され、製品歩留の著しい向上が認めら
れ、核燃料保管用ラツクや使用済み核燃料保管用
ラツク等の小形化と低コスト化に有利な薄肉化が
容易なことが分る。[Table] Example 2 B1.9wt%, C0.006wt%, Si0.69wt%, Mn1.78wt%, Cr19.4wt%, Ni11.3wt%, P0.023wt%, S0.008wt%, remainder substantially Molten austenitic stainless steel consisting of Fe,
Internal dimensions: Top side 172mm x width 284mm, bottom side length 129mm x width 279mm
Into a mold with a height of 577 mm and a mold thickness of 80 mm, an iron tube made of C0.18% mild steel is inserted into a mold with inner dimensions of top side 158 mm x width 270 mm, bottom side length 114 mm x width 265 mm, height 570 mm, plate thickness 7 mm. Then, it was cast in a vacuum atmosphere inside this iron cylinder with a bottom, and a 7 mm thick iron skin was welded to the outer circumferential surface.
It was made into a 170Kg steel ingot. This steel ingot was heated to 1220℃ and hammer-forged with a reduction rate of 10% to 60% per pass, resulting in a thickness of 50%.
It was shaped into a rolled material with dimensions of mm x width 260 mm x length 1850 mm. After that, it is heated to 1210℃, and the rolling reduction rate per pass is
Hot rolling is performed at 50%, 32%, 29%, 25%, 28%, and 23%, and the plate thickness is 5 mm x width 280 mm x length in 6 passes.
It was made into a board with dimensions of 17410mm. After hot rolling, it was divided into four parts in the longitudinal direction and heated at 1050℃.
After softening for 0.5 hours, cooling with water, cutting off the soft iron layer on the outer surface of the board, and correcting the flatness with a leveler, the final finished size was 4 mm.
It was made into a board with dimensions of 260 mm wide and 4300 mm long. In addition, as a comparative example, austenitic stainless steel with the above composition was forged and hot rolled as it was,
The final dimensions were the same: 4mm thick x 260mm wide x 4300mm long. The number of heating times, edge cracking, and product yield (final product/steel ingot x 100%) during processing of the two types of hot-rolled austenitic stainless steel materials obtained were investigated, and the results are shown in Table 2. As is clear from the results in Tables 1 and 2, the production method of the present invention greatly improves the hot rollability of high B-containing austenitic stainless steel, which is difficult to process, and significantly improves product yield. It can be seen that it is easy to reduce the thickness of nuclear fuel storage racks, spent nuclear fuel storage racks, etc., which is advantageous for downsizing and lowering costs.
Claims (1)
％、Ni7.0wt％〜16wt％系オーステナイトステン
レス鋼の溶鋼を、鋳型内に嵌入した鉄筒内に注入
し、外周面に鉄筒を溶着した鋳塊に造塊し、前記
鋼塊を950℃〜1250℃で分塊圧延あるいは鍛造し、
整形後、950℃〜1250℃に加熱し、１パス当りの
圧下率10％〜70％で、少なくとも１回の熱間圧延
を行なうことを特徴とするＢ含有オーステナイト
ステンレス鋼の製造方法。1 Cr15wt% to 21wt containing B0.5wt% to 3.0wt%
%, 7.0wt% Ni to 16wt% Ni series austenitic stainless steel is injected into a steel cylinder fitted in a mold, an ingot is formed with a steel cylinder welded to the outer circumferential surface, and the steel ingot is heated at 950°C. Blooming or forging at ~1250℃,
A method for producing B-containing austenitic stainless steel, which comprises heating the steel to 950°C to 1250°C after shaping and hot rolling at least once at a rolling reduction rate of 10% to 70% per pass.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4146485A JPS61201727A (en) | 1985-03-01 | 1985-03-01 | Manufacture of b-containing austenitic stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4146485A JPS61201727A (en) | 1985-03-01 | 1985-03-01 | Manufacture of b-containing austenitic stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61201727A JPS61201727A (en) | 1986-09-06 |
| JPS6411082B2 true JPS6411082B2 (en) | 1989-02-23 |
Family
ID=12609095
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4146485A Granted JPS61201727A (en) | 1985-03-01 | 1985-03-01 | Manufacture of b-containing austenitic stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61201727A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2546549B2 (en) * | 1991-02-28 | 1996-10-23 | 新日本製鐵株式会社 | Method for producing B-containing austenitic stainless steel |
| CN106392077B (en) * | 2016-10-09 | 2019-03-19 | 中国核动力研究设计院 | A kind of preparation method of high-boron stainless steel plate |
-
1985
- 1985-03-01 JP JP4146485A patent/JPS61201727A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61201727A (en) | 1986-09-06 |
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