JP3537530B2 - Hot rolling method for stainless steel with reduced occurrence of ear breaks - Google Patents
Hot rolling method for stainless steel with reduced occurrence of ear breaksInfo
- Publication number
- JP3537530B2 JP3537530B2 JP09145395A JP9145395A JP3537530B2 JP 3537530 B2 JP3537530 B2 JP 3537530B2 JP 09145395 A JP09145395 A JP 09145395A JP 9145395 A JP9145395 A JP 9145395A JP 3537530 B2 JP3537530 B2 JP 3537530B2
- Authority
- JP
- Japan
- Prior art keywords
- stainless steel
- hot
- weight
- rolled
- ferrite
- 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 - Fee Related
Links
- 238000005098 hot rolling Methods 0.000 title claims description 25
- 229910001220 stainless steel Inorganic materials 0.000 title claims description 20
- 239000010935 stainless steel Substances 0.000 title claims description 19
- 238000000034 method Methods 0.000 title claims description 11
- 229910000859 α-Fe Inorganic materials 0.000 claims description 33
- 238000005096 rolling process Methods 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052715 tantalum Inorganic materials 0.000 claims description 3
- 230000007797 corrosion Effects 0.000 description 13
- 238000005260 corrosion Methods 0.000 description 13
- 229910001039 duplex stainless steel Inorganic materials 0.000 description 11
- 229910001566 austenite Inorganic materials 0.000 description 9
- 230000000694 effects Effects 0.000 description 9
- 230000007547 defect Effects 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 238000005520 cutting process Methods 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 5
- 238000001953 recrystallisation Methods 0.000 description 5
- 239000010959 steel Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 230000001737 promoting effect Effects 0.000 description 3
- 239000013078 crystal Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000005501 phase interface Effects 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000009966 trimming Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- 102220479482 Puromycin-sensitive aminopeptidase-like protein_C21D_mutation Human genes 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、耳切れ等の欠陥発生が
なく、または耳切れの程度を軽減し、表面品質の優れた
ステンレス鋼熱延板を製造する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hot-rolled stainless steel sheet having excellent surface quality without occurrence of defects such as cut edges or reducing the degree of cut edges.
【０００２】[0002]
【従来の技術】二相ステンレス鋼は、オーステナイト系
ステンレス鋼に比較して耐応力腐食割れ性に優れてお
り、フェライト系ステンレス鋼に比較して溶接性に優れ
ている。この二層ステンレス鋼は、オーステナイト系ス
テンレス鋼をワイヤ等の溶接材料として使用するとき、
形成された溶接ビードに割れが発生することを防止する
ため、溶接材料自体に若干のδフェライトが含まれるよ
うに成分調整している。この二相ステンレス鋼は機械的
性質の異なるオーステナイト（γ）相とフェライト
（δ）相が同時に含まれているため、分塊圧延，熱間圧
延等の熱間加工の際にγ相／δ相との界面から割れが発
生し易く、熱間加工性が著しく悪い。これは熱間圧延時
の応力が変形抵抗や変形能の異なるオーステナイトマト
リックスとδフェライトとの境界に集中し、相界面に亀
裂，破断等の欠陥が発生し易くなることに起因するもの
で、これらの欠陥は熱延時に耳切れとなって現れ、製品
歩留りを低下させる。2. Description of the Related Art Duplex stainless steel has excellent stress corrosion cracking resistance as compared with austenitic stainless steel, and has excellent weldability as compared with ferritic stainless steel. When this austenitic stainless steel is used as a welding material for wires and the like,
In order to prevent cracks from being generated in the formed weld bead, the composition is adjusted so that the welding material itself contains a small amount of δ ferrite. Since this duplex stainless steel contains an austenitic (γ) phase and a ferrite (δ) phase having different mechanical properties at the same time, the γ phase / δ phase is used during hot working such as bulk rolling and hot rolling. Cracks are easily generated from the interface with, and the hot workability is extremely poor. This is because the stress during hot rolling is concentrated on the boundary between the austenitic matrix and the δ ferrite, which have different deformation resistance and deformability, and cracks, fractures, and other defects tend to occur at the phase interface. Defects appear as ear breaks during hot rolling and lower the product yield.
【０００３】δフェライトを含むオーステナイト系又は
二相系ステンレス鋼の熱間加工性を改善するため、従来
から種々の方法が提案されている。たとえば、特公昭５
７−１５６６０号公報では、オーステナイト相の変形能
に悪影響を及ぼすＳ，Ｏ等の不純物含有量を低く抑え、
相界面に偏析する不純物の濃度を低下させている。特公
昭５９−１４０９９号公報では、粒界に偏析し割れ発生
の原因となるＳ含有量を０．００５重量％以下に低減す
ると共に、Ｂ添加によって熱間加工性を改善している。
特開平４−８８１５１号公報では、フェライト相及びオ
ーステナイト相間のバランスをＳ含有量との関係におい
て定量的に調整することにより、安定して熱間加工性を
改善し、歩留りよくステンレス鋼を熱間圧延する方法を
開示している。更に、特開平５−２５５７３７号公報で
は、Ｓ含有量を０．００１重量％以下に規制したステン
レス鋼を幅殺し圧延することにより、熱延時の耳切れが
防止されることを紹介している。[0003] In order to improve the hot workability of austenitic or duplex stainless steel containing δ ferrite, various methods have been conventionally proposed. For example,
In Japanese Patent Application Laid-Open No. 7-15660, the content of impurities such as S and O, which adversely affect the deformability of the austenite phase, is reduced.
The concentration of impurities segregating at the phase interface is reduced. In Japanese Patent Publication No. 59-14099, the S content that causes segregation at grain boundaries and causes cracks is reduced to 0.005% by weight or less, and hot workability is improved by adding B.
Japanese Patent Application Laid-Open No. 4-88151 discloses that the balance between the ferrite phase and the austenite phase is quantitatively adjusted in relation to the S content to stably improve hot workability and to improve the yield rate of stainless steel. A method of rolling is disclosed. Furthermore, Japanese Patent Application Laid-Open No. 5-255737 discloses that by cutting and rolling a stainless steel in which the S content is regulated to 0.001% by weight or less, cutting off during hot rolling can be prevented.
【０００４】[0004]
【発明が解決しようとする課題】Ｓ含有量を低減するた
めに希土類元素が通常添加されているが、希土類元素は
製造コストを上昇させるばかりでなく、スラブ鋳造時に
タンディッシュノズル閉塞等の製造性を悪化させる原因
にもなる。また、スラブ幅の製造バラツキと熱間圧延に
おける幅殺し量にもバラツキを生じることから、幅殺し
の範囲が狭い場合には、必要な幅殺し量が得られないこ
とがある。本発明は、このような問題を解消すべく案出
されたものであり、熱延温度域における所定量のδフェ
ライト量に対して、幅圧下を行うことにより、粗圧延の
途中で熱処理する必要なく、高歩留りでスラブ，ビレッ
ト等の鋳片を熱延することを目的とする。Rare earth elements are usually added to reduce the S content. However, the rare earth elements not only increase the production cost but also increase the productivity of the tundish nozzle during slab casting. It can be a cause of worsening. In addition, since the manufacturing variation of the slab width and the width reduction amount in hot rolling also vary, a necessary width reduction amount may not be obtained when the width reduction range is narrow. The present invention has been devised in order to solve such a problem, and it is necessary to perform a heat treatment in the course of rough rolling by performing width reduction on a predetermined amount of δ ferrite in a hot rolling temperature range. It is intended to hot roll slabs, billets, and other cast pieces at a high yield.
【０００５】[0005]
【課題を解決するための手段】本発明の熱延方法は、そ
の目的を達成するため、熱間圧延されるステンレス鋼を
式（１）で定義されるδフェライト量Ｘが０〜１２％と
なるように成分調整し、幅圧下量−１０〜２５ｍｍで粗
圧延した後、目標板厚に熱間圧延することを特徴とす
る。
Ｘ＝３．０×（Ｃｒ％＋１．５×Ｓｉ％＋Ｍｏ％）−
２．８×（Ｎｉ％＋０．５×Ｍｎ％＋０．５×Ｃｕ％＋
３０×Ｃ％＋３０×Ｎ％）−１９．８％
熱間圧延されるステンレス鋼の式（１）で定義されるδ
フェライト量Ｘが９〜１２％にあるとき幅圧下量５〜２
５ｍｍで粗圧延し、δフェライト量Ｘが０〜８％にある
とき幅圧下量−１０〜２５ｍｍで粗圧延した後、目標板
厚に熱間圧延することことが好ましい。熱間圧延される
ステンレス鋼としては、Ｃ：０．０３０重量％以下，
Ｎ：０．０４０重量％以下，Ｓｉ：０．６０重量％以
下，Ｍｎ：２．００重量％以下，Ｃｒ：１８．０〜２
１．５０重量％，Ｎｉ：９．５〜１２．８重量％，Ｍ
ｏ：０．５０重量％以下，Ｃｕ：０．２０重量％以下及
び必要に応じてＮｂ，Ｔａの１種又は２種：０．５０〜
１．１０重量％を含むステンレス鋼が使用される。According to the hot rolling method of the present invention, in order to attain the object, a stainless steel to be hot-rolled has a δ ferrite content X defined by the formula (1) of 0 to 12%. It is characterized in that components are adjusted so as to obtain a rough rolling with a width reduction of -10 to 25 mm, and then hot-rolled to a target thickness. X = 3.0 × (Cr% + 1.5 × Si% + Mo%) −
2.8 × (Ni% + 0.5 × Mn% + 0.5 × Cu% +
30 × C% + 30 × N%)-19.8% δ as defined by equation (1) for hot rolled stainless steel
When the ferrite amount X is 9 to 12%, the width reduction amount is 5 to 2
After rough rolling at 5 mm and rough rolling at a width reduction of -10 to 25 mm when the δ ferrite amount X is 0 to 8%, it is preferable to hot roll to a target sheet thickness. As the stainless steel to be hot-rolled, C: 0.030% by weight or less,
N: 0.040% by weight or less, Si: 0.60% by weight or less, Mn: 2.00% by weight or less, Cr: 18.0 to 2
1.50% by weight, Ni: 9.5 to 12.8% by weight, M
o: 0.50% by weight or less, Cu: 0.20% by weight or less and, if necessary, one or two kinds of Nb and Ta: 0.50 to 0.50% by weight.
Stainless steel containing 1.10% by weight is used.
【０００６】[0006]
【作用】熱延される鋳片Ｓは、図１に模式的に示すよう
に、上ロール１と下ロール２との間で圧下される。熱延
時の塑性変形は、鋳片Ｓの中央部ではロールと圧延材の
摩擦力で拘束され、主として鋳片Ｓの圧延方向に沿った
二次元変形となる。鋳片Ｓの幅方向両側部では開放され
た自由端となっているため、鋳片Ｓの長手方向に延びる
二次元変形に加えて、矢印で示した側方に延びる三次元
の塑性変形となる。そのため、幅方向両端部で塑性流動
が大きくなり、結晶粒界に割れ，破断等の圧延欠陥が生
じ易い。幅方向両側部における圧延欠陥の発生メカニズ
ムを調査・研究する過程で、本発明者等は、熱延温度域
において所定のδフェライト量に対しては、板幅方向に
も鋳片を所定量圧下することにより、圧延欠陥の発生が
効果的に抑制されることを見い出した。The cast slab S to be hot-rolled is reduced between the upper roll 1 and the lower roll 2 as schematically shown in FIG. The plastic deformation at the time of hot rolling is restricted by the frictional force between the roll and the rolled material at the center of the slab S, and is mainly a two-dimensional deformation along the rolling direction of the slab S. Since both ends in the width direction of the slab S are open free ends, in addition to two-dimensional deformation extending in the longitudinal direction of the slab S, three-dimensional plastic deformation extending laterally as indicated by an arrow is obtained. . Therefore, plastic flow increases at both ends in the width direction, and rolling defects such as cracks and breaks are likely to occur at crystal grain boundaries. In the process of investigating and studying the mechanism of generation of rolling defects on both sides in the width direction, the present inventors determined that for a predetermined amount of δ ferrite in the hot rolling temperature range, the slab was also reduced by a predetermined amount in the sheet width direction. By doing so, it has been found that the occurrence of rolling defects is effectively suppressed.
【０００７】幅圧下は、上下ロール１，２と直交又は傾
斜する方向に配置された竪ロールを鋳片の幅方向端部に
押し付けることによって行われる。幅圧下と水平圧下の
組合せによる加工履歴により、鋳片両端部粗大組織の動
的再結晶促進によるδフェライトの分散等が図られ、変
形能及び延性が改善される。δフェライト量が９％以上
となる成分範囲では、５ｍｍ未満の軽圧下により動的再
結晶が生じるのに十分な歪みを蓄積することは困難であ
り、材料の延性改善も不十分である。しかし、２５ｍｍ
を超える幅圧下を付与するためには、非常に大きな加重
を幅方向に加えることになり、粗熱延工程での座屈現象
等に起因した操業上の問題が顕在化する。二相ステンレ
ス鋼は、熱延板の所与の特性を付与するために、所定量
以上のδフェライトを含有する必要がある。通常、オー
ステナイト単相又はフェライト単相の場合、結晶粒界の
結合力が強く、変形に伴う再結晶促進の効果も大きい。
しかし、オーステナイト相とフェライト相の結晶粒界の
結合力は非常に弱く、変形に伴う再結晶促進の効果も小
さい。The width reduction is performed by pressing a vertical roll, which is arranged in a direction orthogonal or inclined to the upper and lower rolls 1 and 2, against the widthwise end of the slab. Due to the processing history of the combination of the width reduction and the horizontal reduction, dispersion of δ ferrite is promoted by promoting dynamic recrystallization of the coarse structure at both ends of the slab, and the deformability and ductility are improved. In the component range where the amount of δ ferrite is 9% or more, it is difficult to accumulate enough strain to cause dynamic recrystallization under a light pressure of less than 5 mm, and it is also insufficient to improve the ductility of the material. But 25mm
In order to apply a width reduction exceeding the range, an extremely large load is applied in the width direction, and operational problems due to the buckling phenomenon in the rough hot rolling process become apparent. The duplex stainless steel needs to contain a predetermined amount or more of δ ferrite in order to impart the given properties of the hot-rolled sheet. Usually, in the case of a single phase of austenite or a single phase of ferrite, the bonding force at the crystal grain boundaries is strong, and the effect of promoting recrystallization accompanying deformation is large.
However, the bonding strength between the grain boundaries of the austenite phase and the ferrite phase is very weak, and the effect of accelerating recrystallization accompanying deformation is small.
【０００８】式（１）で定義されるδフェライト量Ｘが
８％以下となるように成分調整したものでは、幅圧下を
行わなくても良好なホットコイルに製造できるものもあ
る。更に、図２に示されるように、式（１）で定義され
るδフェライト量Ｘが８％を超える範囲に成分調整され
たものでは、コイル端部に亀裂が生じ、耳切れ深さが増
大する。この場合には、幅圧下を行うことにより、動的
再結晶促進の効果が大きくなり、耳切れの程度が改善さ
れたホットコイルを製造することができる。しかし、式
（１）で定義されるδフェライト量Ｘが１３％を超える
と、耳切れ深さが急激に増大し、５〜２５ｍｍの幅殺し
圧延を実施しても、ホットコイルの耳切れ深さはある程
度改善されるが、完全に耳切れのない良好なホットコイ
ルを製造することができない。以上の点から、本発明で
は、δフェライト量Ｘを０〜１２％の範囲に規定した。
δフェライト相に対する規制及び幅圧下量は、単独でも
耳切れ防止手段として有効なものであるが、このように
両者を組み合わせることにより、相乗的に欠陥が防止さ
れる。特にその効果が顕著な範囲は、式（１）で定義さ
れるδフェライト量が６〜１０％である。[0008] Some of the components adjusted so that the amount X of δ ferrite defined by the formula (1) is 8% or less can produce a good hot coil without reducing the width. Further, as shown in FIG. 2, when the δ ferrite content X defined by the formula (1) is adjusted to a component exceeding 8%, cracks occur at the coil ends, and the cut-out depth increases. I do. In this case, by performing the width reduction, the effect of promoting dynamic recrystallization is increased, and a hot coil with an improved degree of edge cut can be manufactured. However, when the amount of δ ferrite X defined by the formula (1) exceeds 13%, the cut depth sharply increases, and the cut depth of the hot coil is increased even when the width-cut rolling of 5 to 25 mm is performed. Although this is somewhat improved, it is not possible to produce a good hot coil without any nicks. From the above points, in the present invention, the amount X of δ ferrite is specified in the range of 0 to 12%.
Although the regulation and the width reduction of the δ ferrite phase are effective alone as a means for preventing cutting of the ear, the defect is synergistically prevented by combining the two. The range where the effect is particularly remarkable is where the amount of δ ferrite defined by the formula (1) is 6 to 10%.
【０００９】二相ステンレス鋼のフェライト相及びオー
ステナイト相のバランスは、成分で一義的に定まるもの
ではなく、熱処理温度と共に変動することが知られてい
る。すなわち、高温ではフェライト単相に近い組織が８
００〜９００℃付近の温度域をノーズにオーステナイト
が析出して二相組織となる。このことは、Ｓ固溶度及び
二相組織の変形能の違いの面から考慮するとき、熱間加
工性においてフェライトが多い１２００℃以上の高温で
抽出し、加工を加えた方がより有利である。他方、オー
ステナイトが析出する９００℃未満の条件で熱延するこ
とは不利になる。また、スラブを中心部まで均一な組織
とするためには、熱延前に１５０分以上の十分な加熱を
行う必要がある。スラブ加熱条件は、二相ステンレス鋼
においてフェライト生成量が高くなる高温で長時間加熱
した方が熱間加工性に対して有利となる。１２００℃未
満の条件で熱処理すると、熱延初期からオーステナイト
が生成し熱間加工性が低下する。そのため、スラブ抽出
温度は、１２００℃以上が好ましい。また、スラブを中
心部まで均一な組織とするために、熱延前の加熱を１５
０分以上かけて十分に行う必要がある。[0009] It is known that the balance between the ferrite phase and the austenite phase of a duplex stainless steel is not uniquely determined by the components but varies with the heat treatment temperature. That is, at a high temperature, the structure close to a ferrite single phase is 8
Austenite precipitates in the temperature range around 00 to 900 ° C. in a nose to form a two-phase structure. This means that when considering the difference between the S solid solubility and the deformability of the two-phase structure, it is more advantageous to extract and process at a high temperature of 1200 ° C. or more, which is rich in ferrite in hot workability. is there. On the other hand, hot rolling at a temperature lower than 900 ° C. where austenite precipitates is disadvantageous. Further, in order to make the slab have a uniform structure up to the center, it is necessary to perform sufficient heating for 150 minutes or more before hot rolling. As for the slab heating conditions, it is more advantageous to perform hot workability for a long time at a high temperature at which the amount of ferrite generated in the duplex stainless steel increases. When heat treatment is performed at a temperature lower than 1200 ° C., austenite is generated from the beginning of hot rolling, and hot workability is reduced. Therefore, the slab extraction temperature is preferably 1200 ° C. or higher. Further, in order to make the slab have a uniform structure up to the center, heating before hot rolling is performed for 15 minutes.
It is necessary to perform this sufficiently over 0 minutes.
【００１０】次に、本発明に従って熱延されるステンレ
ス鋼の成分及びその含有量について説明する。
Ｃ：０．０３０重量％以下
鋼中に不可避的に含まれる元素である。Ｃ含有量が低減
すると、炭化物の生成が少なくなり、加工性が向上す
る。また、耐食性及び耐粒界腐食割れ性も向上する。こ
のような効果は、０．０３０重量％以下のＣ含有量で顕
著になる。
Ｎ：０．０４０重量％以下
二相ステンレス鋼の耐食性をバランスよく保持し、シグ
マ相の析出を抑制し、靭性を向上させる作用を呈する。
しかし、０．０４０重量％を超えるＮ含有量は、固溶度
を超えることから、過剰の窒化物が鋼中に発生し、製品
に欠陥を生じさせる。
Ｓｉ：０．６０重量％以下
脱酸剤として鋼に添加される元素である。しかし、Ｓｉ
含有量が０．６０重量％を超えると、シグマ相の生成能
が高くなり、靭性や耐食性が劣化する。Next, the components of stainless steel to be hot-rolled according to the present invention and the contents thereof will be described. C: 0.030% by weight or less An element inevitably contained in steel. When the C content is reduced, generation of carbides is reduced, and workability is improved. Further, corrosion resistance and intergranular corrosion cracking resistance are also improved. Such effects become remarkable at a C content of 0.030% by weight or less. N: 0.040% by weight or less The effect of maintaining the corrosion resistance of the duplex stainless steel in a well-balanced manner, suppressing the precipitation of the sigma phase, and improving the toughness.
However, an N content exceeding 0.040% by weight exceeds the solid solubility, so that excessive nitrides are generated in the steel, causing defects in the product. Si: 0.60% by weight or less An element added to steel as a deoxidizing agent. However, Si
When the content exceeds 0.60% by weight, the ability to form a sigma phase increases, and the toughness and corrosion resistance deteriorate.
【００１１】Ｍｎ：２．００重量％以下
溶接性を向上させる上で有用な合金元素である。しか
し、Ｍｎ含有量が２．００重量％を超えるようになる
と、耐食性が低下する。
Ｃｒ：１８．００〜２１．５０重量％
耐食性を向上させるために必要不可欠な合金元素であ
る。１６重量％よりも少ないＣｒ含有量では、耐食性が
十分でない。特に二相ステンレス鋼が使用される過酷な
腐食環境においては、Ｃｒ含有量が１８．００重量％未
満では耐食性が十分でなく、またフェライト相に比率も
低下する。逆に、２１．５０重量％を超える多量のＣｒ
が含まれると、シグマ相が析出し易くなり、靭性や溶接
性が劣化する。
Ｎｉ：９．５〜１２．８重量％
耐食性の向上に有効に作用すると共に、オーステナイト
又は二相組織を形成するために不可欠な合金元素であ
る。Ｎｉ含有量に関しては、Ｃｒ含有量等との関係で適
切な組織を得るために、その含有範囲を９．５〜１２．
８重量％とした。Mn: 2.00% by weight or less Mn is an alloy element useful for improving weldability. However, when the Mn content exceeds 2.00% by weight, the corrosion resistance decreases. Cr: 18.0 to 21.50% by weight An alloy element indispensable for improving corrosion resistance. If the Cr content is less than 16% by weight, the corrosion resistance is not sufficient. Particularly, in a severe corrosive environment where a duplex stainless steel is used, if the Cr content is less than 18.00% by weight, the corrosion resistance is not sufficient, and the ratio of the ferrite phase decreases. Conversely, a large amount of Cr exceeding 21.50% by weight
, A sigma phase is easily precipitated, and toughness and weldability are deteriorated. Ni: 9.5 to 12.8% by weight Ni is an alloy element that effectively acts to improve corrosion resistance and is indispensable for forming austenite or a two-phase structure. Regarding the Ni content, in order to obtain an appropriate structure in relation to the Cr content and the like, the content range is 9.5 to 12.1.
It was 8% by weight.
【００１２】Ｍｏ：０．５０重量％以下
Ｃｒと共同してＣｌ- イオンを含む腐食環境における局
部腐食に対する抵抗力を高める合金元素である。しか
し、Ｍｏは、高価な元素である上、０．５０重量％を超
えて添加すると、二相ステンレス鋼においてはシグマ相
析出に起因した脆化が生じ、加工性や靭性等を劣化させ
る。
Ｃｕ：０．２０重量％以下
耐応力腐食割れ性や耐亜硫酸ガス腐食性を向上させる上
で、有効な合金元素である。しかし、０．２０重量％を
超える多量のＣｕを含有させると、熱間加工性が低下す
る。
本発明に従って熱延されるステンレス鋼は、以上の合金
元素の外に、Ｎｂ及びＴａの１種又は２種を、合計量で
０．５０〜１．１０重量％添加することができる。この
範囲でＮｂ及び／又はＴａを添加するとき、耳切れ抑制
作用が損なわれず、それぞれの合金元素特有の作用・効
果が発揮される。Mo: 0.50% by weight or less Mo is an alloy element which increases the resistance to local corrosion in a corrosive environment containing Cl - ions in combination with Cr. However, Mo is an expensive element, and when added in excess of 0.50% by weight, embrittlement due to sigma phase precipitation occurs in the duplex stainless steel, deteriorating workability and toughness. Cu: 0.20% by weight or less Cu is an effective alloy element for improving stress corrosion cracking resistance and sulfurous acid gas corrosion resistance. However, when a large amount of Cu exceeding 0.20% by weight is contained, hot workability deteriorates. In the stainless steel to be hot-rolled according to the present invention, in addition to the above alloying elements, one or two of Nb and Ta can be added in a total amount of 0.50 to 1.10% by weight. When Nb and / or Ta is added in this range, the effect of suppressing ear cutting is not impaired, and the functions and effects unique to each alloy element are exhibited.
【００１３】[0013]
実施例１：二相ステンレス鋼約４０〜８０トンを溶製
し、スラブを製造した。得られたスラブの表面疵を取り
除いた後、スラブを加熱炉で１２５０℃×１７０分の加
熱条件で加熱した後、抽出し、表１に示した幅圧下の条
件で熱延した。得られた熱延鋼板を観察し、板幅方向両
端部における耳切れの発生状況を調査した。調査結果を
示す図２にみられるように、式（１）で定義されるδフ
ェライト量Ｘの増加に従って耳切れ発生量が増加してお
り、その増加と共に急激に耳切れ深さが増加している。
また、幅圧下圧延を施したものでは、幅出し圧延のもの
に比較して耳切れ深さが軽減されている。幅圧下圧延を
施しても式（１）で定義されるδフェライト量Ｘが１０
％を超えると、耳切れ発生が軽減されても耳切れ深さが
ゼロにはならないので、トリミングする必要があり、歩
留りの低下を来した。Example 1: About 40 to 80 tons of duplex stainless steel was melted to produce a slab. After removing the surface flaws of the obtained slab, the slab was heated in a heating furnace under heating conditions of 1250 ° C. × 170 minutes, extracted, and hot-rolled under the conditions of width pressure shown in Table 1. The resulting hot-rolled steel sheet was observed, and the occurrence of edge cuts at both ends in the sheet width direction was investigated. As can be seen from FIG. 2 showing the results of the investigation, the amount of cut-out increases as the amount X of δ ferrite defined by the equation (1) increases, and the cut-off depth sharply increases with the increase. I have.
Further, in the case where the width reduction rolling is performed, the edge cutting depth is reduced as compared with the case where the width reduction rolling is performed. Even when width reduction rolling is performed, the amount of δ ferrite X defined by the equation (1) is 10
%, The ear cutting depth does not become zero even if the occurrence of ear cutting is reduced, so that it is necessary to perform trimming, resulting in a decrease in yield.
【００１４】[0014]
【表１】 [Table 1]
【００１５】[0015]
【発明の効果】以上に説明したように、本発明において
は、式（１）で定義されるδフェライト量Ｘが０〜１２
％となるように成分調整すると共に、熱延時に５〜２５
ｍｍの幅圧下を行うことにより、粗圧延の途中で再加熱
する必要がなく、二相系ステンレス鋼の熱延時に板幅方
向両端部に発生しがちであった耳切れを抑制又は軽減す
ることができる。そのため、得られた熱延鋼板は、耳切
れ部分を除去するトリミング代を小さくすることが可能
となり、高い歩留りで製品となる。As described above, according to the present invention, the amount X of δ ferrite defined by the formula (1) is 0-12.
% As well as 5 to 25 during hot rolling.
By reducing the width by mm, it is not necessary to reheat during the course of rough rolling, and it is possible to suppress or reduce the edge breaks that tend to occur at both ends in the sheet width direction during hot rolling of duplex stainless steel. Can be. For this reason, the obtained hot-rolled steel sheet can reduce the trimming margin for removing the cut-out portion, and is a product with a high yield.
【図１】 熱延時における板幅方向両端部のメタルフロ
ーFig. 1 Metal flow at both ends in the sheet width direction during hot rolling
【図２】 δフェライト量及び幅圧下量が耳切れに及ぼ
す影響Fig. 2 Effect of the amount of δ-ferrite and width reduction on cut edge
１：上ロール ２：下ロール Ｓ：熱延中の鋳片 1: Upper roll 2: Lower roll S: Slab during hot rolling
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭64−71503（ＪＰ，Ａ) 特開 昭57−155322（ＪＰ，Ａ) 特開 昭60−240301（ＪＰ，Ａ) 特開 昭61−154703（ＪＰ，Ａ) 特開 昭64−53704（ＪＰ，Ａ) 特開 平６−279856（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B21B 1/00 - 3/02 C21D 7/13 C22C 38/00 - 38/60 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-71503 (JP, A) JP-A-57-155322 (JP, A) JP-A-60-240301 (JP, A) JP-A 61-155 154703 (JP, A) JP-A-64-53704 (JP, A) JP-A-6-279856 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) B21B 1 / 00-3 / 02 C21D 7/13 C22C 38/00-38/60
Claims (5)
で定義されるδフェライト量Ｘが０〜１２％となるよう
に成分調整し、幅圧下量−１０〜２５ｍｍで粗圧延した
後、目標板厚に熱間圧延することを特徴とする耳切れの
発生を抑制したステンレス鋼の熱延方法。 Ｘ＝３．０×（Ｃｒ％＋１．５×Ｓｉ％＋Ｍｏ％）−２．８×（Ｎｉ％ ＋０．５×Ｍｎ％＋０．５×Ｃｕ％＋３０×Ｃ％＋３０×Ｎ％）−１９．８％ ・・・・（１）The stainless steel to be hot-rolled is represented by the formula (1)
The composition is adjusted so that the amount X of δ ferrite defined by the formula is 0 to 12%, rough-rolled with a width reduction of -10 to 25 mm, and then hot-rolled to a target plate thickness. Hot rolling method for stainless steel with reduced generation. X = 3.0 × (Cr% + 1.5 × Si% + Mo%) − 2.8 × (Ni% + 0.5 × Mn% + 0.5 × Cu% + 30 × C% + 30 × N%) − 19. 8% ... (1)
で定義されるδフェライト量Ｘが９〜１２％となるよう
に成分調整し、幅圧下量５〜２５ｍｍで粗圧延した後、
目標板厚に熱間圧延することを特徴とする耳切れの発生
を抑制したステンレス鋼の熱延方法。 Ｘ＝３．０×（Ｃｒ％＋１．５×Ｓｉ％＋Ｍｏ％）−２．８×（Ｎｉ％ ＋０．５×Ｍｎ％＋０．５×Ｃｕ％＋３０×Ｃ％＋３０×Ｎ％）−１９．８％ ・・・・（１）2. The hot-rolled stainless steel is represented by the formula (1)
After adjusting the components so that the amount X of δ ferrite defined by the formula is 9 to 12%, and rough rolling with a width reduction of 5 to 25 mm,
A hot-rolling method for stainless steel in which the occurrence of edge breaks is suppressed, characterized in that hot rolling is performed to a target thickness. X = 3.0 × (Cr% + 1.5 × Si% + Mo%) − 2.8 × (Ni% + 0.5 × Mn% + 0.5 × Cu% + 30 × C% + 30 × N%) − 19. 8% ... (1)
で定義されるδフェライト量Ｘが０〜８％となるように
成分調整し、幅圧下量−１０〜２５ｍｍで粗圧延した
後、目標板厚に熱間圧延することを特徴とする耳切れの
発生を抑制したステンレス鋼の熱延方法。 Ｘ＝３．０×（Ｃｒ％＋１．５×Ｓｉ％＋Ｍｏ％）−２．８×（Ｎｉ％ ＋０．５×Ｍｎ％＋０．５×Ｃｕ％＋３０×Ｃ％＋３０×Ｎ％）−１９．８％ ・・・・（１）3. The stainless steel to be hot-rolled is represented by the formula (1)
The composition is adjusted so that the amount X of δ ferrite defined by the formula is 0 to 8%, rough-rolled with a width reduction of -10 to 25 mm, and then hot-rolled to a target plate thickness. Hot rolling method for stainless steel with reduced generation. X = 3.0 × (Cr% + 1.5 × Si% + Mo%) − 2.8 × (Ni% + 0.5 × Mn% + 0.5 × Cu% + 30 × C% + 30 × N%) − 19. 8% ... (1)
４０重量％以下，Ｓｉ：０．６０重量％以下，Ｍｎ：
２．００重量％以下，Ｃｒ：１８．０〜２１．５０重量
％，Ｎｉ：９．５〜１２．８重量％，Ｍｏ：０．５０重
量％以下及びＣｕ：０．２０重量％以下を含むステンレ
ス鋼を熱間圧延する請求項１〜３の何れかに記載の熱延
方法。4. C: 0.030% by weight or less, N: 0.0
40% by weight or less, Si: 0.60% by weight or less, Mn:
2.00% by weight or less, Cr: 18.0 to 21.50% by weight, Ni: 9.5 to 12.8% by weight, Mo: 0.50% by weight or less, and Cu: 0.20% by weight or less The hot rolling method according to any one of claims 1 to 3, wherein the stainless steel is hot-rolled.
Ｎｂ，Ｔａの１種又は２種：０．５０〜１．１０重量％
を含むステンレス鋼を使用する請求項１〜３の何れかに
記載の熱延方法。5. The stainless steel according to claim 4, further comprising one or more of Nb and Ta: 0.50 to 1.10% by weight.
The hot rolling method according to any one of claims 1 to 3, wherein a stainless steel containing:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09145395A JP3537530B2 (en) | 1995-03-24 | 1995-03-24 | Hot rolling method for stainless steel with reduced occurrence of ear breaks |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP09145395A JP3537530B2 (en) | 1995-03-24 | 1995-03-24 | Hot rolling method for stainless steel with reduced occurrence of ear breaks |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08257607A JPH08257607A (en) | 1996-10-08 |
| JP3537530B2 true JP3537530B2 (en) | 2004-06-14 |
Family
ID=14026792
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP09145395A Expired - Fee Related JP3537530B2 (en) | 1995-03-24 | 1995-03-24 | Hot rolling method for stainless steel with reduced occurrence of ear breaks |
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| Country | Link |
|---|---|
| JP (1) | JP3537530B2 (en) |
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|---|---|---|---|---|
| CN117483424B (en) * | 2023-11-17 | 2024-06-04 | 燕山大学 | Axially movable special-shaped roller for improving edge crack of magnesium alloy plate and rolling method |
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1995
- 1995-03-24 JP JP09145395A patent/JP3537530B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08257607A (en) | 1996-10-08 |
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