JPH0114966B2 - - Google Patents
Info
- Publication number
- JPH0114966B2 JPH0114966B2 JP4146385A JP4146385A JPH0114966B2 JP H0114966 B2 JPH0114966 B2 JP H0114966B2 JP 4146385 A JP4146385 A JP 4146385A JP 4146385 A JP4146385 A JP 4146385A JP H0114966 B2 JPH0114966 B2 JP H0114966B2
- Authority
- JP
- Japan
- Prior art keywords
- stainless steel
- austenitic stainless
- steel
- cracks
- rolling
- 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 32
- 239000010959 steel Substances 0.000 claims description 32
- 229910000963 austenitic stainless steel Inorganic materials 0.000 claims description 23
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 20
- 238000005096 rolling process Methods 0.000 claims description 11
- 238000005242 forging Methods 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 238000007493 shaping process Methods 0.000 claims description 2
- 238000002788 crimping Methods 0.000 claims 1
- 239000000463 material Substances 0.000 description 18
- 238000005098 hot rolling Methods 0.000 description 17
- 229910001220 stainless steel Inorganic materials 0.000 description 8
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 229910052759 nickel Inorganic materials 0.000 description 7
- 239000003758 nuclear fuel Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000010935 stainless steel Substances 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000002915 spent fuel radioactive waste Substances 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 241000316887 Saissetia oleae Species 0.000 description 1
- 208000009205 Tinnitus Diseases 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000009749 continuous casting 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
- 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
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000012805 post-processing Methods 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
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- 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％含有量の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、熱間加工時に割れ易く、また一旦割れ
が生じると硼化物によつて、割れが伝播し、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つて製品化できず、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
び焼付け防止のためであり、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
鋼塊を、そのままかあるいは、
長方形状に整形後、鋼塊の少なくとも４主面を
鉄筒にて密着包囲し、分塊圧延あるいは鍛造によ
り圧着させたのち、
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
ンレス鋼塊を、
ｂ 例えば、型抜き用勾配のついた鋳塊の場合、
そのままか、あるいは、軽鍛造して、勾配のな
い均一断面形状からなる長方形に整形するか、
あるいは連続鋳造によるスラブ鋳片またはビレ
ツト鋳片を所要寸法に切断整形し、
ｃ 得られた長方形状の整形鋼塊の少なくとも４
主面、すなわち、長手方向の両端面を除く上下
面と両側面の４主面あるいは全表面の黒皮を除
去し、清浄化し、
ｄ この４主面あるいは全表面を、炭素鋼あるい
はステンレス鋼からなるパイプや板による溶接
組立体などの鉄筒にて密着包囲し、
ｅ 上記鉄筒と整形鋼塊とを950℃〜1250℃にて
分塊圧延あるいは鍛造により圧着させたのち、
ｆ 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、
ｇ 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
担度を矯正し、
ｈ 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
ンレス鋼を歩留よく得る製造方法である。
この発明において、上記ｄ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、整形鋼
塊の４主面を包囲するほか、全面を完全被包する
ことも、鋼塊の温度降下防止に有効であり、引張
力軽減のためには４主面中、特に、熱間圧延時の
長手方向縁部にあたる両側面及び縁部との密着が
重要であり、上記の整形鋼塊を完全被包したの
ち、鉄筒に穿孔して鉄筒と鋼塊との間を真空とな
してから封孔したほうが、整形鋼塊と鉄筒との溶
着性が向上するため好ましい。
また、鉄筒の材質は、熱間変形抵抗及び熱膨腸
特性を一致させるため、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２mm〜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
は以下のとおりである。
熱間加工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、加工材の温度が低下すると
ともに加工時に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相からなつており、温度低
下や引張力の負荷により、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ため、特に切
期の割れやひび疵を発生させないことが重要であ
り、この発明方法では素材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圧延時の引張力が、前記
の鉄筒により緩和される。
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。従つて、分塊圧延あるいは鍛造
前に、鋼塊に鉄筒を密着包囲し、熱間加工後に表
面を切削し、表面を清浄化したのち、再度、鉄筒
にて密着包囲し、熱間圧延に供してもよいが、歩
留、作業性、鉄筒の密着性を考慮すると、鉄筒の
厚みを適切にして、分塊圧延あるいは鍛造前に密
着包囲し、これを除去することなく、熱間圧延
時、熱間圧延後の処理まで鉄筒により密着保護さ
せた状態とするのが望ましい。
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％を超える含有で
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
気における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、Gr15wt％〜
21wt％、Ni7.0〜16wt％
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、応力腐蝕割れを発生し易くなるた
め、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
B1.8wt％、C0.005wt％、
Si0.41wt％、Mn1.49wt％、
Cr18.5wt％、Ni11.4wt％
P0.010wt％、S0.004wt％、
残部実質的にFe
からなるオーステナイトステンレス鋼を、上辺
270mm×155mm下辺265mm×115mm高さ560mm寸法の
160Kgの平板状鋼塊となし、手入により鋳肌表面
を除去して清浄化し、押湯部切断後、長手方向の
上下面と両側面の４主面に、厚み７mmのC0.15％
の鋼板の溶接組立体よりなる軟鋼筒にて密着包囲
すると共に、長手両端に、該軟鋼筒との間を
Cr19.8wt％、Ni10.0wt％よりなるオーステナイ
トステンレス鋼にて溶接封じをし、これをプレス
鍛造により、1050℃で、厚み65mm×幅280mm×長
さ1235mmに仕上鍛造し、軟鋼筒を圧着させた。
その後、1220℃に加圧し、１パス当りの圧下率
54％、40％、33％、33％の熱間圧延を行ない、板
厚８mm×幅320mm×長さ8780mm寸法の板材となし
た。
熱間圧延後に、1000℃、0.5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、長手２分割し、レベラーにより平担度を
矯正し、最終仕上寸法として、板厚７mm×幅300
mm×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７mm×幅300mm×長さ4300mm寸法の最
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 Cr15wt containing B0.5wt% to 3.0wt% used for nuclear fuel assembly transportation containers, nuclear fuel storage racks, spent nuclear fuel storage racks, etc.
% to 21 wt% and Ni to 7.0 wt% to 16 wt% austenitic stainless steel, and particularly relates to a method of manufacturing 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. When this occurs, cracks propagate due to borides, and the hot working temperature range that can be worked with few cracks is narrow, making the material difficult to work. Cracks and cracks are more likely to occur on the edges, making post-processing impossible and resulting in poor yields. For this reason, various studies have been conducted to improve the hot rolling properties of B-containing austenitic stainless steels, and in 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. 54-1989).
-6842), but this is for the purpose of preventing oxidation and seizure, rather than improving the difficult-to-work properties of an alloy consisting of two phases of boride and austenite, 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 enveloping material, and there is a risk that the enveloping 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 the formation of cracks 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. Composition of the Invention This invention comprises 15 wt% to 21 wt% of Cr containing 0.5 wt% to 3.0 wt% of B;
A 7.0 wt% Ni to 16 wt% Ni austenitic stainless steel ingot is either left as is or after being shaped into a rectangular shape, at least four main surfaces of the steel ingot are closely surrounded by iron cylinders, and the ingot is crimped by blooming rolling or forging. , Heating to 950℃~1250℃, 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% ~ 16wt% austenitic stainless steel ingot, b For example, in the case of an ingot with a slope for die cutting,
Either leave it as is, or lightly forge it and shape it into a rectangular shape with a uniform cross-sectional shape without slope.
Alternatively, a continuous casting slab or billet slab is cut and shaped into the required dimensions, c. At least 4 of the obtained rectangular shaped steel ingots are
Remove black scales from the main surfaces, that is, the top and bottom surfaces and both side surfaces excluding both ends in the longitudinal direction, or the entire surface, and clean them, and d. The steel tube is closely surrounded by a steel tube such as a welded assembly of pipes or plates, and the steel tube and the shaped steel ingot are crimped by blooming rolling or forging at 950℃ to 1250℃, and then f 950℃ to 1250℃. After heating to 1250℃ and hot rolling at least once at a rolling reduction rate of 10% to 70% per pass, g. Or straighten the flatness with a leveler, then remove the outermost iron layer on the outer peripheral surface of the hot-rolled material, and if necessary, straighten the flatness with cold rolling or a leveler, and then roll the hot-rolled material during hot rolling. This is a manufacturing method for producing high-B content austenitic stainless steel of good quality with no cracks or cracks on the longitudinal edges at a high yield. In this invention, the iron cylinder d above can be a pipe-shaped or welded assembly made of plate materials, and in addition to surrounding the four main surfaces of the shaped steel ingot, it can also be completely encapsulated on the entire surface, and the steel cylinder can reduce the temperature of the steel ingot. In order to reduce the tensile force, it is important to have close contact with the four main surfaces, especially both sides and edges, which correspond to the longitudinal edges during hot rolling. After being encapsulated, it is preferable to drill a hole in the steel tube to create a vacuum between the steel tube and the steel ingot and then seal the hole, since this improves the weldability between the shaped steel ingot and the steel tube. In addition, stainless steel may be used as the material for the steel tube in order to match hot deformation resistance and thermal expansion properties, but from a cost perspective, mild steel is preferable, and the thickness of the steel tube should be adjusted until the end of hot rolling. The thickness is required to be enough to remain, preferably 2 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 is as follows. Due to roll contact during hot working or the influence of cooling water and ambient temperature, the temperature of the workpiece decreases and various tensile forces are applied during working, resulting in the so-called ear cracking described above. It consists of two phases: a phase and an austenite phase, and cracks and cracks occur due to temperature drops and tensile force loads.
Once they occur, cracks and cracks propagate one after another due to boride, making it impossible to produce a product. Therefore, it is especially important to prevent cracks and cracks from occurring at the cutting stage. The iron cylinder prevents the above-mentioned temperature drop, and also relieves the tensile force that tends to be applied to the longitudinal edges during rolling. The effects of the manufacturing method of the present invention are not only effective during hot rolling but also during blooming rolling or forging, and the forging is effective whether it is hammer forging or press forging. Therefore, before blooming or forging, a steel tube is tightly enclosed in a steel ingot, and after hot working, the surface is cut and the surface is cleaned, and then the steel tube is tightly enclosed again and hot rolled. However, in consideration of yield, workability, and adhesion of the steel tube, the thickness of the steel tube should be made appropriate, the tube should be tightly enclosed before blooming or forging, and heat treatment should be carried out without removing it. During inter-rolling, it is desirable that the steel tube be closely protected until the treatment after hot rolling. Reasons for limiting the invention The reasons for limiting the components of the austenitic stainless steel in this invention are as follows. B is included 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. % range. Cr is contained in this system along 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.
If the content exceeds 16 wt%, 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 16 wt%. 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, Gr15wt%~
It is an austenitic stainless steel consisting of 21wt% Ni, 7.0 to 16wt% Ni, and the balance substantially 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. Since P and S tend to cause stress corrosion cracking, P and S need to be kept at 0.05 wt% or less and S at 0.03 wt% 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 B1.8wt%, C0.005wt%, Si0.41wt%, Mn1.49wt%, Cr18.5wt%, Ni11.4wt% P0.010wt%, S0.004wt%, balance essentially made of Fe The upper side is made of austenitic stainless steel.
Dimensions: 270mm x 155mm bottom side 265mm x 115mm height 560mm
A 160Kg flat steel ingot was prepared, the cast surface was removed and cleaned, and after the feeder section was cut, a 7mm thick C0.15% steel ingot was applied to the four main surfaces, top and bottom and both sides in the longitudinal direction.
It is tightly surrounded by a mild steel tube made of a welded assembly of steel plates, and there are gaps between the tube and the mild steel tube at both longitudinal ends.
Welded and sealed austenitic stainless steel consisting of 19.8wt% Cr and 10.0wt% Ni, press-forged this at 1050℃ to a thickness of 65mm x width 280mm x length 1235mm, and crimped a mild steel tube. Ta. Then, pressurize to 1220℃ and reduce the rolling reduction rate per pass.
Hot rolling was performed at 54%, 40%, 33%, and 33% to obtain a plate with dimensions of 8 mm thick x 320 mm wide x 8780 mm long. After hot rolling, heat treatment is performed at 1000℃ for 0.5 hours, water-cooled, the soft iron layer on the outer surface of the plate is removed, the length is divided into two parts, the flatness is corrected using a leveler, and the final finished dimensions are as follows: Plate thickness 7mm x width 300
It was made into a board with dimensions of mm x length 4300 mm. In addition, as a comparative example, austenitic stainless steel with the above composition was forged and hot rolled as it was,
The final dimensions of the same plate were 7mm thick x 300mm 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 1.
【表】
実施例 ２
B2.0wt％、C0.03wt％、
Si0.53wt％、Mn1.45wt％、
Cr17.8wt％、Ni12.10wt％
P0.011wt％、S0.006wt％、
残部実質的にFe
からなるオーステナイトステンレス鋼を、勾配比
3.4を有する180Kgの平板状鋼塊となし、これを軽
鍛造して、黒皮を除去し、厚み110mm×幅250mm×
長さ770mm寸法の均一断面を有する長方形状に整
形手入後、表面を清浄化し、これを、厚み８mm、
外径126mm×266mm、内径110mm×250mm、長さ770
mm寸法のC0.18％の軟鋼筒に装入し、長手両端に
つき、該軟鋼筒との間をCr19wt％、Ni9.5wt％よ
りなるオーステナイトステンレス鋼にて溶接封じ
をし、これをハンマー鍛造により、1100℃で、厚
み70mm×幅270mm×長さ1365mmに仕上鍛造し、軟
鋼筒を圧着させた。
その後、1180℃に加熱し、１パス当りの圧下率
34％の熱間圧延を行ない、２パスで板厚30mm×幅
275mm×長さ3125mm寸法となし、1210℃に再加熱
し、１パス当りの圧下率43％、41％及び30％の３
パスの熱間圧延を行ない、板厚７mm×幅285mm×
長さ12900mm寸法の板材となした。
熱間圧延後に長手方向に３分割し、1050℃、１
時間の熱処理を行ない、水冷後レベルにより平担
度を矯正し、板材の外表面の軟鉄層部分を切削除
去し、最終仕上寸法として、板厚６mm×幅270mm
×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２表にその結果を示す。[Table] Example 2 B2.0wt%, C0.03wt%, Si0.53wt%, Mn1.45wt%, Cr17.8wt%, Ni12.10wt% P0.011wt%, S0.006wt%, balance essentially Fe Austenitic stainless steel consisting of gradient ratio
A 180Kg flat steel ingot with 3.4
After shaping into a rectangular shape with a uniform cross section of 770 mm in length, the surface was cleaned and this was shaped into a rectangular shape with a thickness of 8 mm.
Outer diameter 126mm x 266mm, inner diameter 110mm x 250mm, length 770
It is charged into a C0.18% mild steel cylinder with dimensions of mm, and the space between the longitudinal ends and the mild steel cylinder is welded and sealed with austenitic stainless steel consisting of 19wt% Cr and 9.5wt% Ni, and then hammer forged. It was finish forged at 1100℃ to a thickness of 70mm x width of 270mm x length of 1365mm, and a mild steel cylinder was crimped. After that, it is heated to 1180℃, and the rolling reduction rate per pass is
34% hot rolling, 30mm thick x width in 2 passes
The dimensions were 275mm x length 3125mm, reheated to 1210℃, and the rolling reduction rate per pass was 43%, 41%, and 30%.
After hot rolling, the plate thickness is 7mm x width 285mm x
It was made into a board with a length of 12,900 mm. After hot rolling, it was divided into three parts in the longitudinal direction and heated at 1050°C for 1
Heat treatment is performed for several hours, and after water cooling, the flatness is corrected by leveling, and the soft iron layer on the outer surface of the board is removed.The final dimensions are 6 mm thick x 270 mm wide.
It was made into a board with a length of 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 situation, 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.
【表】
第１表及び第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加工性が
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] As is clear from the results in Tables 1 and 2, the manufacturing method of the present invention produces high B
The hot workability of austenite-containing stainless steel has been significantly improved, and the product yield has been significantly improved, and thinner walls are advantageous for downsizing and cost reduction of nuclear fuel storage racks and spent nuclear fuel storage racks. It turns out it's easy.
Claims (1)
％、Ni7.0wt％〜16wt％系オーステナイトステン
レス鋼塊を、そのままかあるいは、長方形状に整
形後、鋼塊の少なくとも４主面を鉄筒にて密着包
囲し、分塊圧延あるいは鍛造により圧着させたの
ち、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%
%, Ni7.0wt% to 16wt% type austenitic stainless steel ingot, either as it is or after shaping into a rectangular shape, tightly surrounding at least four main surfaces of the steel ingot with iron cylinders, and crimping by blooming rolling or forging. A method for producing a B-containing austenitic stainless steel, which is then heated to 950°C to 1250°C and hot rolled at least once at a rolling reduction rate of 10% to 70% per pass.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4146385A JPS61201726A (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 |
|---|---|---|---|
| JP4146385A JPS61201726A (en) | 1985-03-01 | 1985-03-01 | Manufacture of b-containing austenitic stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61201726A JPS61201726A (en) | 1986-09-06 |
| JPH0114966B2 true JPH0114966B2 (en) | 1989-03-15 |
Family
ID=12609068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4146385A Granted JPS61201726A (en) | 1985-03-01 | 1985-03-01 | Manufacture of b-containing austenitic stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61201726A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0830213B2 (en) * | 1986-10-09 | 1996-03-27 | 日新製鋼株式会社 | Method for producing boron-containing austenitic stainless steel strip |
| JPS63220904A (en) * | 1987-03-11 | 1988-09-14 | Nkk Corp | Pack rolling method for boron added austenitic stainless steel |
| JPH0723510B2 (en) * | 1988-01-30 | 1995-03-15 | 日新製鋼株式会社 | Method for producing hot coil of boron-containing austenitic stainless steel |
| US5119929A (en) * | 1988-11-09 | 1992-06-09 | Acme Manufacturing | Integrated buffing and grinding system |
| 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 JP4146385A patent/JPS61201726A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61201726A (en) | 1986-09-06 |
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