JPH0681037A - Production of hot rolled strip of dual phase stainless steel - Google Patents
Production of hot rolled strip of dual phase stainless steelInfo
- Publication number
- JPH0681037A JPH0681037A JP23200192A JP23200192A JPH0681037A JP H0681037 A JPH0681037 A JP H0681037A JP 23200192 A JP23200192 A JP 23200192A JP 23200192 A JP23200192 A JP 23200192A JP H0681037 A JPH0681037 A JP H0681037A
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- Japan
- Prior art keywords
- stainless steel
- hot
- duplex stainless
- rolling
- temperature
- 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.)
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- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、耳割れなどの欠陥の
ない表面品質の良好な二相ステンレス鋼熱延鋼帯を効率
よく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 efficiently producing a hot-rolled duplex stainless steel strip having a good surface quality without defects such as ear cracks.
【０００２】[0002]
【従来の技術】二相ステンレス鋼は、耐海水性をはじめ
とする優れた耐食性を有するため、各種化学工業プラン
トや海洋構造物など、広範な分野において賞用されてい
る。Duplex stainless steel has excellent corrosion resistance including seawater resistance, and is therefore widely used in various fields such as various chemical industrial plants and marine structures.
【０００３】しかし、二相ステンレス鋼は熱間加工性が
良くないため、連続熱間圧延で鋼帯を製造する際に、熱
延板に耳割れ等の表面欠陥が発生し、またコイル巻取り
時にコイル破断が起こりやすく、生産の歩留りと能率が
低下するという問題がある。However, since the duplex workability of the duplex stainless steel is not good, surface defects such as edge cracks are generated on the hot rolled sheet when the steel strip is manufactured by the continuous hot rolling, and the coil winding is performed. Sometimes, coil breakage easily occurs, which causes a problem that production yield and efficiency are reduced.
【０００４】そのために、従来二相ステンレス鋼の鋼帯
の製造は鋼塊法で製造したインゴットを分塊圧延して得
たスラブあるいは連続鋳造法により製造したスラブを事
前に加工−熱処理して熱間圧延をしてきた。For this reason, in the conventional production of a duplex stainless steel strip, a slab obtained by slab-rolling an ingot produced by the ingot method or a slab produced by a continuous casting method is heat-treated in advance by heat treatment. Has been rolling for a while.
【０００５】例えば、特開昭52−6330号公報には、二相
ステンレス鋼の分塊圧延前あるいは厚板圧延前または厚
板圧延後の仕上処理において、鋼に 500〜 800℃で温間
加工を加えてフェライト粒を伸長粒にすると同時に粒界
に析出したオーステナイト相を分断し、その後 900〜11
00℃に１〜20hr保持して、フェライト粒とオーステナイ
ト粒を整粒化して均一なフェライト−オーステナイト二
相共存鋼とすることにより、耳割れの発生を防止する方
法が開示されている。[0005] For example, Japanese Patent Laid-Open No. 52-6330 discloses that a duplex stainless steel is warm-worked at 500 to 800 ° C. in a finishing treatment before slab rolling, thick plate rolling or after thick plate rolling. Is added to make the ferrite grains elongated, and at the same time the austenite phase precipitated at the grain boundaries is divided, and then 900 to 11
A method for preventing the occurrence of ear cracking is disclosed by keeping the ferrite particles and the austenite particles at 00 ° C for 1 to 20 hours to form a uniform ferrite-austenite dual phase steel.
【０００６】一方、本出願人は二相ステンレス鋼の化学
組成および熱間圧延法の両面から改善を加えて、耳割れ
およびコイル破断を防止する発明をなし、先に特許出願
を行った (特開平２− 25203号公報参照) 。On the other hand, the present applicant made an invention to prevent ear cracking and coil rupture by improving both the chemical composition of the duplex stainless steel and the hot rolling method, and filed a patent application first (special feature: (See Kaihei 2-25203).
【０００７】上記本出願人の先願の発明の方法では、
Ｂ： 0.002〜 0.008％（以下、成分含有量の％は質量％
を意味する）を含有させて、Mo、Ｗなどの粗大炭化物や
窒化物の粒界偏析を防止して、粒界脆化による割れを防
止する、粗圧延 (予備圧延) でスラブ表面およびコー
ナー部の結晶粒を微細化し、粗圧延後の混粒を再加熱に
より整粒化し、偏析を軽減する、上記の粗圧延の
後、再加熱し、仕上圧延温度 950℃以上で熱間圧延を行
い、σ相の析出を防止して、σ相脆化による割れを防止
する、という改良の総合効果により、熱延板の耳割れ発
生が抑制される。In the method of the invention of the above-mentioned applicant's earlier application,
B: 0.002 to 0.008% (Hereinafter,% of component content is% by mass
) To prevent grain boundary segregation of coarse carbides and nitrides such as Mo and W, and to prevent cracks due to grain boundary embrittlement. Refine the crystal grains, resize the mixed grains after rough rolling to reduce segregation, reduce segregation, after the above rough rolling, reheat and perform hot rolling at a finishing rolling temperature of 950 ° C or higher, Generation of edge cracks in the hot-rolled sheet is suppressed by the overall effect of the improvement of preventing precipitation of the σ phase and preventing cracking due to σ phase embrittlement.
【０００８】また、 450℃以下でコイルに巻取ることに
より、 475℃脆化 (15〜70％のCrを含有するステンレス
鋼を 450〜500 ℃に長時間曝したときに現れる脆化現
象) によるコイル破断が防止される。Also, due to coiling at 450 ° C. or less, embrittlement at 475 ° C. (embrittlement phenomenon that appears when stainless steel containing 15 to 70% Cr is exposed to 450 to 500 ° C. for a long time) Coil breakage is prevented.
【０００９】しかし、上述の方法はいずれも熱間圧延前
に２回以上の加熱、或いは加熱と予備圧延を行う必要が
あり、生産能率が高いとは言えず、実生産上は未だ解決
すべき課題を残している。However, in any of the above-mentioned methods, it is necessary to perform heating twice or more before hot rolling, or heating and pre-rolling, and it cannot be said that the production efficiency is high, and it should be solved in actual production. There are challenges.
【００１０】[0010]
【発明が解決しようとする課題】本発明は、連続鋳造ス
ラブの予備の粗圧延や熱処理を行わなくても耳割れやコ
イル破断を発生させることなしに熱間圧延およびコイル
巻取りを行うことができ、歩留りと生産能率の向上を達
成できる二相ステンレス鋼の熱延鋼帯の製造方法を提供
することを目的とする。SUMMARY OF THE INVENTION According to the present invention, hot rolling and coil winding can be performed without causing edge cracking or coil breakage without preliminary rough rolling or heat treatment of a continuous cast slab. It is an object of the present invention to provide a method for producing a hot-rolled steel strip of duplex stainless steel, which is capable of achieving improved yield and production efficiency.
【００１１】[0011]
【課題を解決するための手段】本発明は、下記Ｉのお
よびの化学組成をもつ二相ステンレス鋼の連続鋳造ス
ラブを、下記IIのプロセスで処理することを特徴とする
二相ステンレス鋼熱延鋼帯の製造方法を要旨とする。DISCLOSURE OF THE INVENTION The present invention is characterized in that a continuous casting slab of a duplex stainless steel having the chemical compositions of I and below is treated by the process of II below. The gist is the method of manufacturing the steel strip.
【００１２】Ｉ．連続鋳造スラブの化学組成（質量％） Ｃ：0.2 ％以下、 Si： 2.0％以下、 Mn： 2.0％
以下、Ｐ：0.04％以下、 Ｓ：0.03％以下、 Cr： 20
〜35％、Mo：0.5 〜 6.0％、Ｎ：0.08〜0.30％、Ni：
4.0〜9.0 ％、Ｂ：0.0020〜0.0080％、 sol.Al:0.010
〜0.050 ％、Ca：0.0010〜0.0080％、残部Feおよび不可
避不純物。I. Chemical composition of continuously cast slab (mass%) C: 0.2% or less, Si: 2.0% or less, Mn: 2.0%
Below, P: 0.04% or less, S: 0.03% or less, Cr: 20
~ 35%, Mo: 0.5-6.0%, N: 0.08-0.30%, Ni:
4.0 to 9.0%, B: 0.0020 to 0.0080%, sol.Al: 0.010
~ 0.050%, Ca: 0.0010 to 0.0080%, balance Fe and unavoidable impurities.
【００１３】 上記の合金成分に加えて、更に、C
u：0.60％以下、Ｗ：0.05〜0.8 ％、Ｖ：0.05〜 1.5
％、Nb：0.01〜 0.5％およびTi：0.01〜0.5 ％の中の１
種以上を含有する組成。In addition to the above alloy components, C
u: 0.60% or less, W: 0.05 to 0.8%, V: 0.05 to 1.5
%, Nb: 0.01-0.5% and Ti: 0.01-0.5%
A composition containing at least one species.
【００１４】II. 処理プロセス 上記組成の連続鋳造スラブを、予備熱処理や予備圧延を
行うことなく、1200〜1300℃の温度に加熱し、仕上温度
950℃以上で熱間圧延し、450 ℃以下で巻き取る。II. Treatment Process The continuous casting slab having the above composition is heated to a temperature of 1200 to 1300 ° C. without performing a preliminary heat treatment or a preliminary rolling, and a finishing temperature is set.
Hot-roll at 950 ° C or higher and wind at 450 ° C or lower.
【００１５】[0015]
【作用】本発明の二相ステンレス鋼熱延鋼帯の製造方法
では、上記の化学組成と処理プロセスの組合せの相乗的
な効果として前記の目的を達成し得るのであるが、特に
二相ステンレス鋼中に適正範囲のＢ、CaおよびAlを含有
させ、熱延加熱からコイル巻取りまでの温度条件を適正
化したことが本発明方法の大きな特徴である。In the method for producing a hot-rolled duplex stainless steel strip according to the present invention, the above object can be achieved as a synergistic effect of the combination of the above chemical composition and the treatment process. It is a major feature of the method of the present invention that B, Ca and Al are contained in appropriate ranges to optimize the temperature conditions from hot rolling heating to coil winding.
【００１６】まず本発明の対象となる二相ステンレス鋼
の化学組成を上述のように限定した理由を説明する。First, the reason why the chemical composition of the duplex stainless steel to which the present invention is applied is limited as described above will be explained.
【００１７】Ｃ： 0.2％以下 Ｃは鋼の強度を得るために通常 0.005％以上含有させる
が、Ｃ含有量が過大になると炭化物が結晶粒界に析出し
て耐食性と熱間加工性を劣化させるので 0.2％以下にと
どめるのがよい。C: 0.2% or less C is usually contained in an amount of 0.005% or more in order to obtain the strength of the steel, but if the C content becomes excessive, carbides precipitate at the grain boundaries, deteriorating the corrosion resistance and hot workability. Therefore, it is better to keep it below 0.2%.
【００１８】Si： 2.0％以下 溶鋼精錬時に脱酸剤として作用するとともに、フェライ
ト生成元素としてフェライト (α) とオーステナイト
(γ) の比率を望ましい範囲に保ち、耐食性を向上させ
る成分である。しかし、Siが 2.0％を超えると鋼の靱性
を害する。Si: 2.0% or less It acts as a deoxidizer during molten steel refining, and ferrite (α) and austenite as ferrite forming elements.
It is a component that maintains the ratio of (γ) within a desired range and improves corrosion resistance. However, if Si exceeds 2.0%, the toughness of steel is impaired.
【００１９】Mn： 2.0％以下 溶鋼精錬時に脱酸剤として作用し、またＳと化合してMn
Ｓを形成して熱間脆性を抑える。さらにオーステナイト
安定化元素として作用するが、二相組織のバランスを保
つために 2.0％以下とする。Mn: 2.0% or less Mn acts as a deoxidizer during refining of molten steel, and combines with S to form Mn.
S forms to suppress hot brittleness. Furthermore, it acts as an austenite stabilizing element, but is 2.0% or less to maintain the balance of the two-phase structure.
【００２０】Ｐ：0.04％以下 Ｐは結晶粒界の結合力を低下させ、熱間加工性を劣化さ
せる不純物である。特に二相ステンレス鋼においては、
Ｐはオーステナイト粒よりもフェライト粒に多く固溶し
てフェライト相の高温変形能を著しく劣化させ、フェラ
イトとオーステナイトの結晶界面からの割れ発生の原因
となる。0.04％は許容上限値であるが、これ以下ででき
るだけ少ない方がよい。P: 0.04% or less P is an impurity that reduces the bond strength of grain boundaries and deteriorates hot workability. Especially in duplex stainless steel,
P forms a solid solution in ferrite grains more than in austenite grains and remarkably deteriorates the high temperature deformability of the ferrite phase, which causes cracking from the crystal interface between ferrite and austenite. 0.04% is an allowable upper limit value, but it is better to be as small as possible below this value.
【００２１】Ｓ：0.03％以下 Ｓも結晶粒界に偏析して結晶粒界の結合力を著しく低下
させ、熱間加工性を劣化させる不純物である。0.03％以
下でできるだけ少ない方がよい。S: 0.03% or less S is also an impurity which is segregated at the crystal grain boundaries to remarkably reduce the bond strength of the crystal grain boundaries and deteriorate the hot workability. It should be as small as possible at 0.03% or less.
【００２２】Cr：20〜35％ Crはフェライト安定化元素で、耐食性の改善のために必
須の成分である。適正な二相組織を得るために20％以上
を含有させる必要がある。しかし、35％を超えるとσ相
脆化が生じやすくなるので上限を35％とする。Cr: 20 to 35% Cr is a ferrite stabilizing element and is an essential component for improving the corrosion resistance. It is necessary to contain 20% or more in order to obtain a proper two-phase structure. However, if it exceeds 35%, σ phase embrittlement tends to occur, so the upper limit is made 35%.
【００２３】Mo： 0.5〜6.0 ％ 二相ステンレス鋼の耐酸性、耐孔食性は主にNi、Cr、M
o、Ｎの含有量で支配される。Moはフェライトをベース
にした二相ステンレス鋼を得るためには 0.5％以上の含
有が必要であるが、6.0 ％を超えると種々の脆化が生じ
やすくなる。Mo: 0.5-6.0% Duplex stainless steels are mainly resistant to acid and pitting corrosion by Ni, Cr and M.
It is controlled by the contents of o and N. Mo must be contained in an amount of 0.5% or more to obtain a duplex stainless steel based on ferrite, but if it exceeds 6.0%, various embrittlements are likely to occur.
【００２４】Ｎ：0.08〜0.30％ Ｎは強力なオーステナイト安定化元素で、耐局部腐食性
と機械的性質、特に引張強さ、靱性、延性を向上させる
ので0.08％以上含有させる。しかし、Ｎ含有量が0.30％
を超えると衝撃遷移温度特性を劣化させる。N: 0.08 to 0.30% N is a strong austenite stabilizing element. It improves the local corrosion resistance and mechanical properties, especially tensile strength, toughness, and ductility, so N is contained by 0.08% or more. However, the N content is 0.30%
If it exceeds, the impact transition temperature characteristics are deteriorated.
【００２５】Ni： 4.0〜9.0 ％ Niも強力なオーステナイト安定化元素で、耐食性の改善
に有効であり、二相ステンレス鋼の基本的な組織と性質
を確保するためには、その含有量を 4.0％以上とする必
要がある。しかし、フェライト・オーステナイトの二相
組織を得るために、Cr、Cu、Mo、Ｎとのバランスを考慮
して上限を 9.0％とする。Ni: 4.0 to 9.0% Ni is also a strong austenite stabilizing element and is effective in improving the corrosion resistance. In order to secure the basic structure and properties of duplex stainless steel, its content should be 4.0 It must be at least%. However, in order to obtain a two-phase structure of ferrite / austenite, the upper limit is set to 9.0% in consideration of the balance with Cr, Cu, Mo and N.
【００２６】Ｂ：0.0020〜0.0080％ Ｂは結晶粒界にＢ炭窒化物として微細に析出し、結晶粒
を微細化するとともに粒界の脆化を防止する作用をもつ
元素である。即ち、Ｂが0.0020％以上になると、熱間加
工性が改善され、熱間圧延時に粒界から発生する耳割れ
が抑制される。B: 0.0020 to 0.0080% B is an element that is finely precipitated as B carbonitride at the crystal grain boundaries to refine the crystal grains and prevent the grain boundaries from becoming brittle. That is, when B is 0.0020% or more, the hot workability is improved and the ear cracks generated from the grain boundaries during hot rolling are suppressed.
【００２７】一方、Ｂが0.0080％を超えるとＢ炭窒化物
が粗大になり、かえって耳割れが発生しやすくなる。On the other hand, when B exceeds 0.0080%, the carbonitride B becomes coarse and, on the contrary, ear cracking is likely to occur.
【００２８】sol.Al： 0.010〜0.050 ％ Alはフェライト安定化元素で、また強力な脱酸剤として
作用し、結晶粒を微細化して熱間加工性を改善する。こ
のような作用効果を得るには 0.010％以上含有量させる
必要がある。ただし、脱酸作用、結晶粒微細化作用は
0.050％までで充分である。Sol.Al: 0.010 to 0.050% Al is a ferrite stabilizing element and also acts as a strong deoxidizing agent to refine the crystal grains and improve the hot workability. In order to obtain such effects, it is necessary to make the content 0.010% or more. However, the deoxidizing action and the grain refining action are
Up to 0.050% is sufficient.
【００２９】Ca：0.0010〜0.0080％ Caは熱間加工性を低下させる鋼中の硫化物をCaＳに置換
して、結晶粒内や粒界に微細に分散させ、粒界の脆化を
防止する。したがってCaを適正量含有させると、耳割れ
の発生を防止することができる。かかる効果が顕著にな
るのはCa含有量が0.0010％以上になったときである。し
かし、その含有量が0.0080％を超えると溶接性等が低下
する。Ca: 0.0010 to 0.0080% Ca replaces the sulfide in the steel that deteriorates the hot workability with CaS and finely disperses it in the crystal grains and grain boundaries to prevent embrittlement of the grain boundaries. . Therefore, the inclusion of an appropriate amount of Ca can prevent the occurrence of ear cracks. Such an effect becomes remarkable when the Ca content is 0.0010% or more. However, if the content exceeds 0.0080%, the weldability and the like deteriorate.
【００３０】本発明の対象となる二相ステンレス鋼は、
上記の成分以外に下記の成分の中から選ばれる１種以上
の成分を含有させることができる。The duplex stainless steel which is the subject of the present invention is
In addition to the above components, one or more components selected from the following components may be included.
【００３１】Cu：0.60％以下 Cuはオーステナイト生成元素で、鋼中に均一に固溶し耐
食性を増す。また浸炭、窒化に対する抵抗を増し、耐酸
化性を向上させるが、0.60％を超えると鋼の熱間加工性
が劣化するので添加する場合はその含有量の上限を0.60
％とする。Cu: 0.60% or less Cu is an austenite-forming element and uniformly forms a solid solution in steel to increase corrosion resistance. It also increases resistance to carburization and nitriding and improves oxidation resistance, but if it exceeds 0.60%, the hot workability of steel deteriorates, so if it is added, the upper limit of its content should be 0.60.
%.
【００３２】Ｗ：0.05〜0.8 ％ Ｗは、その適量がCr、Moと共存する場合に海水に対する
鋼の耐孔食性と耐隙間腐食性を向上させる。その効果は
0.05％未満では発揮されない。一方、Ｗが 0.8％を超え
ると鋼の加工性と溶接性が劣化する。W: 0.05 to 0.8% W improves pitting corrosion resistance and crevice corrosion resistance of steel against seawater when appropriate amounts thereof coexist with Cr and Mo. The effect is
It is not exhibited when it is less than 0.05%. On the other hand, when W exceeds 0.8%, the workability and weldability of steel deteriorate.
【００３３】Ｖ：0.05〜1.5 ％ Ｖはフェライト生成元素であり、0.05％以上を含有させ
ることにより結晶粒を微細化し、高温クリープ強度を増
大させるが多量に添加すると熱間加工性が劣化する。適
正な含有量の範囲は0.05〜1.5 ％である。V: 0.05 to 1.5% V is a ferrite-forming element, and if it is contained in an amount of 0.05% or more, the crystal grains become finer and the high temperature creep strength is increased, but if a large amount is added, hot workability deteriorates. The proper content range is 0.05 to 1.5%.
【００３４】Nb：0.01〜0.5 ％ Nbはフェライト安定化元素であり、0.01％以上含有させ
ることにより微細な炭窒化物を形成して結晶粒を微細化
するとともに耐食性を改善する。しかし 0.5％以上含有
させても効果の増大は少ないので上限値を 0.5％とす
る。Nb: 0.01 to 0.5% Nb is a ferrite stabilizing element, and when it is contained in an amount of 0.01% or more, it forms fine carbonitrides to refine the crystal grains and improve the corrosion resistance. However, if the content is 0.5% or more, the effect does not increase so much, so the upper limit is made 0.5%.
【００３５】Ti：0.01〜0.5 ％ Tiはフェライト生成元素で強化な脱酸・脱窒効果があ
り、Ｃ％の５倍以上の含有量で粒界腐食防止の効果が顕
著になる。しかし、Tiを多量に添加するとTiの酸化物や
窒化物の介在物が生成し、表面性状を劣化させるのでそ
の含有量は0.01〜0.5 ％の範囲とすべきである。Ti: 0.01 to 0.5% Ti is a ferrite forming element and has a strong deoxidizing and denitrifying effect, and the effect of intergranular corrosion prevention becomes remarkable when the content is 5 times or more of C%. However, if a large amount of Ti is added, inclusions of Ti oxides or nitrides are generated and the surface properties are deteriorated, so the content should be in the range of 0.01 to 0.5%.
【００３６】本発明の製造方法においては、上述の化学
組成を有する二相ステンレス鋼を溶製し、連続鋳造によ
ってスラブを製造する。このスラブを必要に応じて適度
に表面疵の手入れをした後、1200〜1300℃に加熱して熱
間圧延を行う。In the manufacturing method of the present invention, the duplex stainless steel having the above-mentioned chemical composition is melted, and the slab is manufactured by continuous casting. This slab is appropriately cared for surface defects, if necessary, and then heated to 1200 to 1300 ° C. for hot rolling.
【００３７】スラブの加熱温度を1200〜1300℃とする理
由は次のとおりである。即ち、加熱温度が1300℃を超え
るとスラブ表面が溶融して、いわゆるバーニング現象が
起こり、加熱炉内でのスラブ形状が悪化し、酸化ロスに
よって歩留りも低下する。また、スラブ加熱温度が1200
℃よりも低い場合には、熱間圧延の仕上温度が低くなり
すぎて、σ相析出温度域で圧延することになり熱延板に
耳割れが発生しやすくなる。The reason for setting the heating temperature of the slab to 1200 to 1300 ° C. is as follows. That is, when the heating temperature exceeds 1300 ° C., the slab surface is melted, a so-called burning phenomenon occurs, the slab shape in the heating furnace deteriorates, and the yield decreases due to oxidation loss. Also, the slab heating temperature is 1200
When the temperature is lower than 0 ° C, the finishing temperature of hot rolling becomes too low, and rolling is performed in the σ phase precipitation temperature range, so that edge cracks are likely to occur on the hot rolled sheet.
【００３８】スラブ加熱後の熱間圧延工程では、およそ
150〜240mm 厚のスラブから２〜８mm厚の鋼帯に圧延す
る。この時、仕上温度（最終パスでの温度）を 950℃以
上とする。前述したように 950℃より低温になるとσ相
が生成し、そこで加工するとσ相脆化による耳割れ等の
欠陥が発生するからである。In the hot rolling step after heating the slab,
Roll from 150-240mm thick slab to 2-8mm thick steel strip. At this time, the finishing temperature (temperature in the final pass) shall be 950 ° C or higher. This is because, as described above, when the temperature is lower than 950 ° C, the σ phase is generated, and when the σ phase is processed there, defects such as ear cracks due to the σ phase embrittlement occur.
【００３９】熱間圧延で製造された鋼帯はコイルに巻取
られる。この巻取り温度を 450℃以下とするのは、これ
より高い温度で巻取ると、450 〜 500℃で 475℃脆性が
現れ、あるいはσ相の生成によりコイルが破断すること
があるからである。The steel strip produced by hot rolling is wound into a coil. The coiling temperature is set to 450 ° C. or lower because coiling at a temperature higher than 450 ° C. may cause brittleness at 475 ° C. at 450 to 500 ° C. or the coil may break due to the formation of σ phase.
【００４０】なお、仕上げ圧延後はσ相の生成防止およ
び 475℃脆性の抑制と工程短縮のために、ホットランス
プレーなどによって冷却することが望ましい。After finish rolling, it is desirable to cool by hot run spraying or the like in order to prevent the formation of σ phase, suppress 475 ° C. brittleness, and shorten the process.
【００４１】上述のごとく、本発明の製造方法において
は素材の二相ステンレス鋼中に熱間加工性を改善する効
果を有するＢ、sol.AlおよびCaを含有させるとともに、
連続鋳造スラブの熱間圧延前の加熱温度、熱延仕上温度
およびコイル巻取り温度がσ相脆性、475 ℃脆性を回避
できるように選定されている。したがって、熱間圧延に
先立ってスラブの予備圧延や熱処理を行わなくても、熱
間圧延中の耳割れなどの欠陥がなく、巻取りの際のコイ
ル破断のない鋼帯を製造することができ、歩留りの向
上、生産能率の向上が達成できる。As described above, in the production method of the present invention, B, sol.Al and Ca having the effect of improving hot workability are contained in the raw material duplex stainless steel, and
The heating temperature, hot rolling finishing temperature and coil winding temperature of the continuously cast slab before hot rolling are selected to avoid σ phase embrittlement and 475 ° C embrittlement. Therefore, without performing preliminary rolling or heat treatment of the slab prior to hot rolling, there is no defect such as edge cracking during hot rolling, and it is possible to manufacture a steel strip without coil breakage during winding. It is possible to improve the yield and the production efficiency.
【００４２】以下、実施例により本発明方法の効果を具
体的に説明する。The effects of the method of the present invention will be specifically described below with reference to examples.
【００４３】[0043]
【実施例】表１に示す組成を有する二相ステンレス鋼
（No.1〜７）を電気炉−ＡＯＤプロセスで溶製し、連続
鋳造によってそれぞれ異なった厚みのスラブにした。な
お、No.1の鋼は、sol.AlとCaの含有量を図１に示すよう
に種々変化させたものを多数溶製し、表１にはその平均
組成を示してある。Example Duplex stainless steels (Nos. 1 to 7) having the compositions shown in Table 1 were melted by an electric furnace-AOD process and continuously cast into slabs having different thicknesses. The No. 1 steel was prepared by melting many sol. Al and Ca contents with various changes as shown in FIG. 1, and Table 1 shows the average composition thereof.
【００４４】上記の各スラブにプレーナーで表面疵手入
れを施した後、後述する表２、表３および表４の各条件
で圧延を行って鋼帯を製造し、そのときの欠陥の発生状
況を調べた。その結果を表２〜４中に併記する。なお、
耳割れは目視観察で検出してその長さを計測した。After each slab was surface-polished with a planer, it was rolled under the conditions shown in Table 2, Table 3 and Table 4 to be described later to manufacture a steel strip. Examined. The results are also shown in Tables 2-4. In addition,
The ear crack was detected by visual observation and its length was measured.
【００４５】[0045]
【表１】 [Table 1]
【００４６】実施例１ 実施例１は本発明の請求項１記載の化学組成を有する二
相ステンレス鋼（表１のNo.1の鋼）であって、sol.Alと
Caの量を図１に示すように変えたものを素材とする例で
あり、表２に示すように事前の粗圧延 (予備圧延) を行
うことなく、本発明の条件で熱間圧延を行った。Example 1 Example 1 is a duplex stainless steel (No. 1 steel in Table 1) having the chemical composition according to claim 1 of the present invention, which is sol.
This is an example of using a material in which the amount of Ca is changed as shown in FIG. 1, and as shown in Table 2, hot rolling is performed under the conditions of the present invention without performing preliminary rough rolling (preliminary rolling). It was
【００４７】比較例１〜４は、Ｂ、sol.Al、Ca無添加の
鋼 (表１のNo.2の鋼) を使用したもので、その比較例１
では予備の粗圧延を２回行い、比較例２では、予備の粗
圧延を３回実施した。比較例４は実施例１とほぼ同じ条
件であるが、熱間圧延の仕上温度を 900℃と低くした。Comparative Examples 1 to 4 are steels containing no B, sol.Al and Ca (No. 2 steel in Table 1).
Then, preliminary rough rolling was performed twice, and in Comparative Example 2, preliminary rough rolling was performed three times. Comparative Example 4 has almost the same conditions as those of Example 1, but the finishing temperature of hot rolling is lowered to 900 ° C.
【００４８】[0048]
【表２】 [Table 2]
【００４９】図１は実施例１の二相ステンレス鋼熱延鋼
板の耳割れ発生状況を示す図である。なお、図中の○印
の中の数字は、耳割れ深さ(mm)を示す。FIG. 1 is a diagram showing the occurrence of edge cracks in the hot rolled duplex stainless steel sheet of Example 1. The numbers in the circles in the figure indicate the depth of cracks in the ear (mm).
【００５０】図に示すように、Ｂ：0.0032％を含有する
素材で、sol.Alの 0.010％以上、Caの0.0010％以上を複
合添加することにより、耳割れ深さは０〜５mmとなり、
耳割れの発生を大幅に抑制ないし防止することができ
る。また表２に示すように、実施例１ではコイル破断は
発生しなかった。As shown in the figure, the content of B: 0.0032% and the combined addition of 0.010% or more of sol.Al and 0.0010% or more of Ca makes the depth of ear cracking 0-5 mm.
The occurrence of ear cracks can be significantly suppressed or prevented. Further, as shown in Table 2, in Example 1, no coil breakage occurred.
【００５１】表２の比較例２および比較例３では、素材
の二相ステンレス鋼がAl、CaおよびＢを含有していない
ため、熱間圧延は本発明の条件を満たし、かつ予備の粗
圧延を実施して熱間圧延の加工度を低下させているにも
かかわらず耳割れの発生が実施例１より著しい。なお、
コイル巻取り温度は、実施例１と同様に450 ℃より低く
したので、コイル破断は発生しなかった。比較例４は熱
間圧延仕上温度が 950℃より低いため耳割れの発生が実
施例１より高い。In Comparative Example 2 and Comparative Example 3 in Table 2, since the duplex stainless steel as a raw material does not contain Al, Ca and B, hot rolling satisfies the conditions of the present invention and preliminary rough rolling. However, the occurrence of edge cracking is more remarkable than in Example 1 even though the workability of hot rolling is reduced by carrying out the above. In addition,
Since the coil winding temperature was lower than 450 ° C. as in Example 1, no coil breakage occurred. In Comparative Example 4, the hot rolling finish temperature was lower than 950 ° C., so that the occurrence of edge cracking was higher than that in Example 1.
【００５２】実施例２ 実施例２は、本発明の請求項２記載の化学組成を有する
二相ステンレス鋼 (表１のNo.3の鋼) を素材とする例で
あり、表３に示すように予備の粗圧延を行うことなく、
本発明の圧延条件で熱間圧延を行った。比較例５では、
Ca無添加のNo.4の鋼を使用し、予備の粗圧延を２回実施
したこと以外は実施例２と同様の熱間圧延を行った。こ
の比較例５では、素材の二相ステンレス鋼がCaを含有し
ていないため、仕上熱間圧延は本発明の条件を満たし、
予備の粗圧延を実施して仕上熱間圧延の加工度を低下さ
せているにもかかわらず耳割れの発生が実施例２より著
しい。また、コイル巻取り温度が 450℃より高いためコ
イル破断が発生した。Example 2 Example 2 is an example using a duplex stainless steel (steel No. 3 in Table 1) having the chemical composition according to claim 2 of the present invention as shown in Table 3. Without preliminary rough rolling
Hot rolling was performed under the rolling conditions of the present invention. In Comparative Example 5,
Hot rolling was performed in the same manner as in Example 2 except that No. 4 steel containing no Ca was used and preliminary rough rolling was performed twice. In Comparative Example 5, since the duplex stainless steel as a raw material does not contain Ca, the finish hot rolling satisfies the conditions of the present invention,
Although the preliminary rough rolling is performed to reduce the workability of the finish hot rolling, the occurrence of edge cracking is more remarkable than in Example 2. In addition, coil rupture occurred because the coil winding temperature was higher than 450 ° C.
【００５３】比較例６および比較例７は、Ｂ、Alおよび
Caを含有するNo.5の鋼を用いたが、比較例６は熱間圧延
の仕上温度が 950℃より低いため耳割れの発生が実施例
２より高い。比較例７はコイル巻取り温度が 450℃より
高いためコイル破断が発生した。これらに対し、本発明
の実施例２では耳割れの発生が極めて少なく、コイル破
断も発生しなかった。Comparative Examples 6 and 7 are B, Al and
Although No. 5 steel containing Ca was used, in Comparative Example 6, the edge temperature was higher than in Example 2 because the finishing temperature of hot rolling was lower than 950 ° C. In Comparative Example 7, the coil winding temperature was higher than 450 ° C., so that coil breakage occurred. On the other hand, in Example 2 of the present invention, the occurrence of ear cracking was extremely small, and the coil did not break.
【００５４】[0054]
【表３】 [Table 3]
【００５５】実施例３ 実施例３は本発明の請求項２記載の化学組成を有する二
相ステンレス鋼 (表１のNo.6の鋼) を素材とする他の例
であり、表４に示すように予備の粗圧延を行うことな
く、本発明の条件で熱間圧延を行った。比較例８および
比較例９は実施例３と同様、Ｂ、Al、Caを含有する素材
(表１のNo.7の鋼) を使用したが、比較例８は熱間圧延
の仕上温度が 950℃より低いため耳割れの発生が実施例
３より多い。比較例９は仕上温度が 950℃より低く、か
つコイル巻取り温度は 450℃より高いために耳割れの発
生は比較例８よりも更に多くなり、コイル破断も発生し
た。Example 3 Example 3 is another example using a duplex stainless steel having the chemical composition according to claim 2 of the present invention (steel No. 6 in Table 1) as a raw material, and is shown in Table 4. Thus, hot rolling was performed under the conditions of the present invention without performing preliminary rough rolling. Similar to Example 3, Comparative Example 8 and Comparative Example 9 are materials containing B, Al, and Ca.
(No. 7 steel in Table 1) was used, but since Comparative Example 8 had a finishing temperature of hot rolling lower than 950 ° C, the occurrence of edge cracking was higher than that in Example 3. In Comparative Example 9, the finishing temperature was lower than 950 ° C. and the coil winding temperature was higher than 450 ° C., so that the occurrence of edge cracking was more than that of Comparative Example 8, and the coil was broken.
【００５６】これに対し、実施例３では耳割れの発生が
極めて少なく、コイル破断も発生しなかった。On the other hand, in Example 3, the occurrence of ear cracks was extremely small, and the coil did not break.
【００５７】[0057]
【表４】 [Table 4]
【００５８】上述のとおり、本発明方法によれば、予備
の粗圧延および再加熱や熱処理を行わず、一回の加熱と
熱間圧延で耳割れの発生が極めて少なく、コイル破断も
発生しない熱延板を製造することができる。比較例の結
果からみて、素材の二相ステンレス鋼中に特に適正量の
Ｂ、AlおよびCaを含有させることと、加工条件を適正に
選ぶことの両方が重要で、この二つの要件の総合効果と
して上記の効果が得られることが明らかである。As described above, according to the method of the present invention, the preliminary rough rolling, reheating and heat treatment are not performed, and the occurrence of edge cracks is extremely small in one heating and hot rolling, and no coil breakage occurs. A rolled sheet can be manufactured. Judging from the results of the comparative example, it is important that both the proper amounts of B, Al and Ca are contained in the duplex stainless steel material and that the processing conditions are properly selected. It is clear that the above effect can be obtained as.
【００５９】[0059]
【発明の効果】本発明方法によれば、通常の熱間圧延に
先立ってスラブを熱処理したり、予備の粗圧延を行っ
て、再加熱してから熱間圧延を行うという手間のかかる
プロセスを採らなくても、耳割れ等の欠陥のない二相ス
テンレス鋼の熱延鋼帯が連続鋳造スラブから製造でき
る。また、コイル巻取り時のコイル破断を防止すること
ができる。したがって、生産能率の向上、製造工程の合
理化および歩留り向上と省エネルギーによる製造コスト
の低減効果が大きい。EFFECTS OF THE INVENTION According to the method of the present invention, a troublesome process of heat-treating a slab prior to normal hot rolling, performing preliminary rough rolling, reheating and then hot rolling is performed. Even if not taken, a hot-rolled strip of duplex stainless steel without defects such as ear cracks can be produced from a continuously cast slab. Further, it is possible to prevent breakage of the coil when winding the coil. Therefore, there are great effects of improving the production efficiency, rationalizing the manufacturing process, improving the yield, and reducing the manufacturing cost by saving energy.
【図１】素材の二相ステンレス鋼のCaおよびsol.Alの含
有量と、熱延板の耳割れ発生との関係を示す図である。FIG. 1 is a diagram showing the relationship between the Ca and sol.Al contents of a duplex stainless steel material and the occurrence of edge cracks in a hot-rolled sheet.
Claims (2)
下、Mn： 2.0％以下、Ｐ：0.04％以下、Ｓ：0.03％以
下、Cr：20〜35％、Mo：0.5 〜 6.0％、Ｎ：0.08〜0.30
％、Ni：4.0 〜 9.0％、Ｂ：0.0020〜0.0080％、sol.A
l：0.010 〜 0.050％およびCa：0.0010〜0.0080％を含
有し、残部Feおよび不可避不純物からなる二相ステンレ
ス鋼の連続鋳造スラブを、1200〜1300℃の温度に加熱
し、仕上温度 950℃以上で熱間圧延し、450 ℃以下で巻
き取ることを特徴とする二相ステンレス鋼熱延鋼帯の製
造方法。1. In mass%, C: 0.2% or less, Si: 2.0% or less, Mn: 2.0% or less, P: 0.04% or less, S: 0.03% or less, Cr: 20-35%, Mo: 0.5-. 6.0%, N: 0.08 to 0.30
%, Ni: 4.0 to 9.0%, B: 0.0020 to 0.0080%, sol.A
l: 0.010-0.050% and Ca: 0.0010-0.0080%, the continuous casting slab of duplex stainless steel containing the balance Fe and unavoidable impurities is heated to a temperature of 1200-1300 ° C at a finishing temperature of 950 ° C or higher. A method for producing hot rolled steel strip of duplex stainless steel, which comprises hot rolling and winding at 450 ° C or lower.
％で、Cu：0.60％以下、Ｗ：0.05〜0.8 ％、Ｖ：0.05〜
1.5 ％、Nb：0.01〜0.5 ％およびTi：0.01〜0.5 ％の中
の１種以上を含有する二相ステンレス鋼の連続鋳造スラ
ブを、1200〜1300℃の温度に加熱し、仕上温度 950℃以
上で熱間圧延し、450 ℃以下で巻き取ることを特徴とす
る二相ステンレス鋼熱延鋼帯の製造方法。2. In addition to the alloy components according to claim 1, further in mass%, Cu: 0.60% or less, W: 0.05-0.8%, V: 0.05-
Continuous casting slab of duplex stainless steel containing at least one of 1.5%, Nb: 0.01 to 0.5% and Ti: 0.01 to 0.5% is heated to a temperature of 1200 to 1300 ° C and a finishing temperature of 950 ° C or more. A method for producing a hot-rolled duplex stainless steel strip, which comprises hot rolling at 450 ° C. and winding at 450 ° C. or lower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4232001A JP2765392B2 (en) | 1992-08-31 | 1992-08-31 | Method for manufacturing hot-rolled duplex stainless steel strip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4232001A JP2765392B2 (en) | 1992-08-31 | 1992-08-31 | Method for manufacturing hot-rolled duplex stainless steel strip |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0681037A true JPH0681037A (en) | 1994-03-22 |
| JP2765392B2 JP2765392B2 (en) | 1998-06-11 |
Family
ID=16932389
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4232001A Expired - Lifetime JP2765392B2 (en) | 1992-08-31 | 1992-08-31 | Method for manufacturing hot-rolled duplex stainless steel strip |
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| Country | Link |
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| JP (1) | JP2765392B2 (en) |
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| JPH0813093A (en) * | 1994-07-04 | 1996-01-16 | Nippon Yakin Kogyo Co Ltd | Superplastic duplex stainless steel small in deformation resistance and excellent in elongating property |
| JPH0841600A (en) * | 1994-05-21 | 1996-02-13 | Yong Soo Park | Corrosion-resistant duplex stainless steel |
| WO1996039543A3 (en) * | 1995-06-05 | 1997-02-20 | Po Hang Iron & Steel | Duplex stainless steel, and its manufacturing method |
| WO1998018974A1 (en) * | 1996-10-29 | 1998-05-07 | Tubacex, S.A. | Austenitic-ferritic steel of the superduplex type applicable to the fabrication of seamless tubes |
| KR100417520B1 (en) * | 1999-12-14 | 2004-02-05 | 주식회사 포스코 | Reheating method for tungsten containing duplex stainless steel |
| KR100568350B1 (en) * | 2001-12-21 | 2006-04-05 | 주식회사 포스코 | Method to produce duplex stainless steel by strip caster |
| KR100804681B1 (en) * | 2006-12-06 | 2008-02-18 | 영남대학교 산학협력단 | Guide roll used for centrifugal casting and manufacturing method thereof |
| JP2014074209A (en) * | 2012-10-05 | 2014-04-24 | Kobe Steel Ltd | Duplex stainless steel material and duplex stainless steel pipe |
| CN105274444A (en) * | 2014-06-19 | 2016-01-27 | 大同特殊钢株式会社 | Steel for cold working tool |
| JP2021143407A (en) * | 2020-03-13 | 2021-09-24 | 日本冶金工業株式会社 | Duplex stainless steel and manufacturing method thereof |
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|---|---|---|---|---|
| JPH01100248A (en) * | 1987-10-09 | 1989-04-18 | Sumitomo Metal Ind Ltd | Two-phase stainless steel and its production |
| JPH0225203A (en) * | 1988-02-22 | 1990-01-26 | Sumitomo Metal Ind Ltd | Manufacture of two-phase stainless steel hot rolling hoop |
| JPH02258956A (en) * | 1989-03-29 | 1990-10-19 | Sumitomo Metal Ind Ltd | Highly corrosion resistant duplex phase stainless steel excellent in hot workability |
| JPH03229839A (en) * | 1990-02-02 | 1991-10-11 | Sumitomo Metal Ind Ltd | Manufacture of duplex stainless steel and its steel material |
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|---|---|---|---|---|
| JPH0841600A (en) * | 1994-05-21 | 1996-02-13 | Yong Soo Park | Corrosion-resistant duplex stainless steel |
| JPH0813093A (en) * | 1994-07-04 | 1996-01-16 | Nippon Yakin Kogyo Co Ltd | Superplastic duplex stainless steel small in deformation resistance and excellent in elongating property |
| WO1996039543A3 (en) * | 1995-06-05 | 1997-02-20 | Po Hang Iron & Steel | Duplex stainless steel, and its manufacturing method |
| US5733387A (en) * | 1995-06-05 | 1998-03-31 | Pohang Iron & Steel Co., Ltd. | Duplex stainless steel, and its manufacturing method |
| WO1998018974A1 (en) * | 1996-10-29 | 1998-05-07 | Tubacex, S.A. | Austenitic-ferritic steel of the superduplex type applicable to the fabrication of seamless tubes |
| US6051081A (en) * | 1996-10-29 | 2000-04-18 | Tubacex, S.A. | Austenitic-ferritic steel of the superduplex type applicable to the fabrication of seamless tubes |
| KR100417520B1 (en) * | 1999-12-14 | 2004-02-05 | 주식회사 포스코 | Reheating method for tungsten containing duplex stainless steel |
| KR100568350B1 (en) * | 2001-12-21 | 2006-04-05 | 주식회사 포스코 | Method to produce duplex stainless steel by strip caster |
| KR100804681B1 (en) * | 2006-12-06 | 2008-02-18 | 영남대학교 산학협력단 | Guide roll used for centrifugal casting and manufacturing method thereof |
| JP2014074209A (en) * | 2012-10-05 | 2014-04-24 | Kobe Steel Ltd | Duplex stainless steel material and duplex stainless steel pipe |
| CN105274444A (en) * | 2014-06-19 | 2016-01-27 | 大同特殊钢株式会社 | Steel for cold working tool |
| JP2021143407A (en) * | 2020-03-13 | 2021-09-24 | 日本冶金工業株式会社 | Duplex stainless steel and manufacturing method thereof |
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