JPH03107411A - Method for refining duplex stainless steel - Google Patents
Method for refining duplex stainless steelInfo
- Publication number
- JPH03107411A JPH03107411A JP1247485A JP24748589A JPH03107411A JP H03107411 A JPH03107411 A JP H03107411A JP 1247485 A JP1247485 A JP 1247485A JP 24748589 A JP24748589 A JP 24748589A JP H03107411 A JPH03107411 A JP H03107411A
- Authority
- JP
- Japan
- Prior art keywords
- molten steel
- stainless steel
- desulfurization
- duplex stainless
- steel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000007670 refining Methods 0.000 title claims abstract description 9
- 229910001039 duplex stainless steel Inorganic materials 0.000 title abstract description 14
- 238000000034 method Methods 0.000 title abstract description 11
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 34
- 239000010959 steel Substances 0.000 claims abstract description 34
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 18
- 230000023556 desulfurization Effects 0.000 claims abstract description 18
- 238000011282 treatment Methods 0.000 claims abstract description 13
- 230000004907 flux Effects 0.000 claims abstract description 12
- 229910001220 stainless steel Inorganic materials 0.000 claims description 13
- 239000010935 stainless steel Substances 0.000 claims description 12
- 238000010992 reflux Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 14
- 229910052760 oxygen Inorganic materials 0.000 abstract description 14
- 239000001301 oxygen Substances 0.000 abstract description 14
- 230000007797 corrosion Effects 0.000 abstract description 12
- 238000005260 corrosion Methods 0.000 abstract description 12
- 230000003628 erosive effect Effects 0.000 abstract 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 229910052717 sulfur Inorganic materials 0.000 description 7
- 239000011593 sulfur Substances 0.000 description 7
- 238000007796 conventional method Methods 0.000 description 4
- 239000011651 chromium Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000011819 refractory material Substances 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000003009 desulfurizing effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000000630 rising effect Effects 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000009849 vacuum degassing Methods 0.000 description 2
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000010412 perfusion Effects 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
〔産業上の利用分野〕
本発明は２相系ステンレス鋼を脱硫及び脱酸する溶製方
法に関する。
〔従来の技術〕
クロムを約１２％以上含有する鋼は、鋼の表面にクロム
の酸化皮膜ができて不動態化し、ずくれた耐食性を示す
のでステンレス鋼とよばれる。ステンレス鋼は組織の上
からマルテンザイト系、フェライト系、オーステナイト
系に大別される。
近年、フェライト／オーステリーイト２相混合組織をも
つ２相系ステンレス鋼が耐応力、腐食割れ性及び面Ｊ孔
食性に優れたステンレス鋼として開発されている。
ところで、一般に大気中で精錬した溶湯は、ガス、非金
属介在物などの不純物成分によるｌη染を受け、そのた
めに成品で種々の欠陥を生ずる。このためステンレス鋼
の品質を向上さセるべく鋼中のガス、非金属介在物など
の不純物の減少、成分範囲の縮小を図る必要がある。
第４図は２相系ステンレス鋼におｋＪる酸素含有量と孔
食発生温度との関係を示すグラフであり、縦軸には孔食
発生温度、横軸には酸素含有量（％）がとられている。
図より明らかな如く、酸素含有量が多いほど孔食発生温
度が低く、孔食が発生し易い。従って２相系ステンレス
鋼の耐食性を向上さセるためには鋼中の酸素含有率を低
下させるべく脱酸処理を行う必要がある。
また第５図は２相系ステンレス鋼にお＋Ｊる硫黄含有量
と成品を熱間で加工した場合のクリープ試験による絞り
率との関係を示すグラフであり、縦軸には絞り率（％）
、横軸には硫黄含有量（ｐｐｍ）が、とられている。図
中Ｏ印でプロソトシであるのは１０００℃で熱間加工し
たもの、Δ印でプロンＩ・しであるのは９００℃で熱間
加工したものである。
図より明らかな如く、硫黄の含有量が同程度である場合
には１０００℃で加工したものの方が、９００℃で加工
したものと比べて絞り率が高い。またどちらの温度で加
工した場合でも硫黄含有量が１０ｐｐｍ以下になると絞
り率が著しく向上し、硫黄含有量が２ ｐｐｍ以下の場
合絞り率〉８０％で耳割れなし、耐食性良好な成品が得
られた。従って２相系ステンレス鋼の熱間加工性（絞り
率）を向上させ良質の成品を得るためには鋼中の硫黄含
有率を低下させるべく脱硫処理を行う必要がある。
ステンレス鋼の脱硫、脱酸方法としては溶鋼を非酸化性
雰囲気下でフラックスにより脱硫する方法（特開昭５３
−１６２０号公報）、また溶鋼を真空脱ガス槽に吹上げ
フラックスにより脱硫する方法、溶鋼を真空脱ガス処理
して脱酸する方法（特開昭５５１０７７１８号公報）が
提案されている。
〔発明が解決しようとする課題〕
一般に鋼中のＣ３）及び[Industrial Field of Application] The present invention relates to a method for desulfurizing and deoxidizing two-phase stainless steel. [Prior Art] Steel containing about 12% or more of chromium is called stainless steel because a chromium oxide film is formed on the surface of the steel, making it passivated and exhibiting poor corrosion resistance. Stainless steel is broadly classified into martensite, ferritic, and austenitic based on its structure. In recent years, a two-phase stainless steel having a ferrite/austerite two-phase mixed structure has been developed as a stainless steel with excellent stress resistance, corrosion cracking resistance, and surface J pitting resistance. By the way, molten metal refined in the atmosphere is generally stained by impurity components such as gas and nonmetallic inclusions, which causes various defects in the finished product. Therefore, in order to improve the quality of stainless steel, it is necessary to reduce impurities such as gas and nonmetallic inclusions in the steel and to narrow the range of its components. Figure 4 is a graph showing the relationship between the oxygen content in kJ and the temperature at which pitting corrosion occurs in duplex stainless steel, with the vertical axis representing the temperature at which pitting corrosion occurs, and the horizontal axis representing the oxygen content (%). It is taken. As is clear from the figure, the higher the oxygen content, the lower the temperature at which pitting corrosion occurs, making it easier for pitting corrosion to occur. Therefore, in order to improve the corrosion resistance of duplex stainless steel, it is necessary to perform deoxidation treatment to reduce the oxygen content in the steel. Figure 5 is a graph showing the relationship between the sulfur content in duplex stainless steel and the reduction rate determined by the creep test when the product is hot-processed, and the vertical axis shows the reduction rate (%).
, the sulfur content (ppm) is plotted on the horizontal axis. In the figure, those marked with O and showing a flat surface are hot worked at 1000°C, and those marked with Δ and showing a flat I are hot worked at 900°C. As is clear from the figure, when the sulfur content is the same, those processed at 1000°C have a higher drawing ratio than those processed at 900°C. In addition, no matter which temperature is used for processing, when the sulfur content is 10 ppm or less, the drawing ratio improves significantly, and when the sulfur content is 2 ppm or less, a product with no edge cracking and good corrosion resistance can be obtained with a drawing ratio of 80%. Ta. Therefore, in order to improve the hot workability (drawing ratio) of duplex stainless steel and obtain a high quality product, it is necessary to perform a desulfurization treatment to reduce the sulfur content in the steel. A method for desulfurizing and deoxidizing stainless steel is to desulfurize molten steel using flux in a non-oxidizing atmosphere (Japanese Patent Laid-Open No. 53
1620), a method in which molten steel is desulfurized by blowing up flux into a vacuum degassing tank, and a method in which molten steel is deoxidized by vacuum degassing treatment (Japanese Patent Laid-Open No. 55107718) has been proposed. [Problem to be solved by the invention] Generally, C3) in steel and
〔０〕の含有率は低ければ低い
ほど良質の成品が得られる。ところが、２相系ステンレ
ス鋼は高クロム鋼（クロム濃度１８％以上）であり、酸
素の活量係数が著しく小さいので溶鋼中の溶存酸素が増
加し、従来の脱酸方法ではステンレス鋼中の酸素を低下
させるのが困難であった。
更に従来の脱硫方法では炉内で脱硫が行われるので炉内
の耐火物が溶損し、安定した脱硫が行えないという問題
があった。
本発明は斯かる問題を解決するためになされたものであ
り、その目的とするところは安定した脱酸処理、脱硫処
理を行い、脱酸率及び脱硫率が高く、耐食性及び熱加工
性が良好な２相系ステンレス鋼を得るための溶製方法を
提供するにある。
〔課題を解決するための手段〕
本発明の２相系ステンレス鋼の溶製方法にあっては、Ａ
１を５％以上混合したフラックスを、溶鋼流に投入する
ことにより脱硫処理を行い、次いで溶鋼中の＾ｌの割合
が０．０２０％以上となるようにＡＩを添加し、ＲＨ真
空精錬装置により環流することにより脱酸処理を行うこ
とを特徴とする。
〔作用〕
本発明の２相系ステンレス鋼の溶製方法にあっては、Ａ
ｎを５％以上混合したフラックスを溶鋼流に投入し一、
溶鋼流のａＯ（ａｃｔｉｖｉｔｙ ｏｘｙｇｅｎ 酸
素活量）を低下させる。これにより炉内の耐火物を溶損
させることなく炉外で安定した脱硫が行われる。
また脱硫後の溶鋼中の＾ｌの割合が０．０２０％以上と
なるように＾ｌを添加し、Ｉ？ｌ（真空精錬装置により
環流することにより酸化された介在物を浮上させる。こ
れにより溶鋼中の溶存酸素が低下され脱酸が行われる。
〔実施例〕
以下、本発明を具体的な実施例に基づいて説明する。
本実施例の対象鋼種である２相系ステンレス鋼（ＷＲＤ
Ｐ８５）の化学成分は次の通りである。
上述の２相系ステンレス鋼を電気炉にて溶解させ、取鍋
からＡＯＤ炉に移し、不活性ガスなどと０□との混合ガ
スを吹き込むごとにより脱Ｃを行う。
またＡＯＤ法によりスラグと溶湯とを撹拌し、Ｃｒを還
元する。
＾０口処理後、ＡＯＤ炉から取鍋へ出鋼中の溶湯にｍｅ
ｔａｌ Ａｊｌ！を５％以以上台したフラックスを出
鋼流にあたる様に投入し出鋼流の反応界面でのａｏ（ａ
ｃｔｉｖｉｔｙ ｏｘｙｇｅｎ酸素活景）を低下させ脱
Ｓを行う。ここで八βの添加率を５％以上としたのは５
％未満ではａｏを低下さ・Ｕる効果が十分得られないか
らである。フラックスの組成例を第２表に示す。
第２表
脱Ｓ処理後、出鋼された取鍋的溶鋼を除滓した後、溶鋼
中の５ｏｌＡＡの割合が０．０２０％以上となるように
ＡＡを添加する。その後溶鋼中にＲ１１真空精錬装置の
上昇管（溶鋼吸い上げ用）と下降管（排出用）とを浸漬
し、上昇管から真空槽内に溶鋼を吸い上げて脱ガスを進
行さセ、これを下降管から排出して７１分間環流する。
これにより鋼中の酸素を減少せしめることができる。
上述の如く溶製された２相系ステンレス鋼の化学成分は
以下に示す如くほとんどすべての成分においてその目標
値が達成され、また（Ｓ）、 （０）の含有量が著し
く低下した。
（以 下 余 白）
第１図は本発明の脱Ｓフランクス（Ａ１１５％以上添加
）及び従来の脱Ｓフランクス（Ａｌｌなし）の脱Ｓ率を
示すグラフである。図より明らかな様に本発明方法のフ
ラックスを用いた場合脱Ｓ率は従来に比して１１ポイン
ト〜２１ポイント向上した。
第２図は成品の５ｏｌＡＪ量（％）とＯ量（ｐｐｍ）と
の関係を示すグラフである。グラフより明らかな如く溶
鋼中の５ｏｌＡ １２が０．０２０％以上になるように
した場合０量を６０ｐｐｍ未溝にすることができる。
第３図はＩ？Ｈ環流時間〔分〕を２０分、４０分、 ６
０分と変化さ・Ｕた場合のｏｎ （ｐｐｍ ）の変化を
示すグラフである。これによるとＩ？ｌ＋環流時間を６
０分以上とし、できるだけ長時間にするほどＯ量を低減
させることがわかる。
〔発明の効果〕
以上詳述した如く本発明の２相系ステンレス鋼の溶製方
法にあっては、Ａｌｌを５％以上混合したフラックスを
？８鋼流に投入して脱硫を行うので、炉内の耐火物が溶
損することなく炉外で安定した脱硫が行われ、従来に比
して脱Ｓ率が向上する。
また脱硫後の溶鋼中にＡＮの割合が０．０２０％以上と
なるようにＡ７！を添加し、Ｒ１１真空精錬装置により
６０分以上環流することにより脱酸が行われ、従来に比
して鋼中のＯ量が減少するという優れた効果を奏する。The lower the content of [0], the higher the quality of the product. However, duplex stainless steel is a high chromium steel (chromium concentration of 18% or more) and has an extremely low oxygen activity coefficient, so dissolved oxygen in the molten steel increases, and conventional deoxidation methods remove the oxygen in the stainless steel. It was difficult to reduce the Furthermore, in the conventional desulfurization method, since desulfurization is performed in a furnace, there is a problem in that the refractories in the furnace are eroded and it is not possible to perform stable desulfurization. The present invention was made to solve such problems, and its purpose is to perform stable deoxidation and desulfurization treatments, have high deoxidation and desulfurization rates, and have good corrosion resistance and heat workability. The object of the present invention is to provide a melting method for obtaining a duplex stainless steel. [Means for Solving the Problems] In the method for producing duplex stainless steel of the present invention, A
Desulfurization treatment is performed by pouring a flux containing 5% or more of 1 into the molten steel flow, then AI is added so that the ratio of ^l in the molten steel is 0.020% or more, and the flux is processed using an RH vacuum refining device. It is characterized by performing deoxidation treatment by refluxing. [Function] In the method for producing duplex stainless steel of the present invention, A
A flux containing 5% or more of n is poured into the molten steel flow.
Decrease the aO (activity oxygen) of the molten steel flow. As a result, stable desulfurization is performed outside the furnace without damaging the refractories inside the furnace. In addition, ^l is added so that the ratio of ^l in the molten steel after desulfurization is 0.020% or more, and I? (The oxidized inclusions are brought to the surface by refluxing in the vacuum refining equipment. This reduces the dissolved oxygen in the molten steel and deoxidizes it. [Example] The present invention will be described below with reference to specific examples. The explanation will be based on duplex stainless steel (WRD), which is the target steel type of this example.
The chemical components of P85) are as follows. The above-mentioned two-phase stainless steel is melted in an electric furnace, transferred from a ladle to an AOD furnace, and decarbonized by blowing in a mixed gas of inert gas or the like and 0□. Further, the slag and molten metal are stirred by the AOD method to reduce Cr. ^0 After processing, add me to the molten metal being tapped from the AOD furnace to the ladle.
tal Ajl! A flux containing 5% or more of
S removal is performed by lowering the oxygen activity (oxygen activity). Here, the addition rate of 8β was set to 5% or more.
This is because if it is less than %, the effect of lowering and increasing the ao cannot be sufficiently obtained. Table 2 shows an example of the composition of the flux. Table 2 After the S removal treatment, the tapped molten steel in the form of a ladle is removed from the slag, and then AA is added so that the proportion of 5olAA in the molten steel is 0.020% or more. After that, the rising pipe (for sucking up molten steel) and the downcomer pipe (for discharging) of the R11 vacuum refining equipment are immersed in the molten steel, and the molten steel is sucked up from the rising pipe into the vacuum tank to proceed with degassing. Drain and reflux for 71 minutes. This makes it possible to reduce oxygen in the steel. As shown below, almost all of the chemical components of the duplex stainless steel melted as described above achieved their target values, and the contents of (S) and (0) were significantly reduced. (Margins below) FIG. 1 is a graph showing the S removal rate of the S-free Franks of the present invention (adding 115% or more of A1) and the conventional S-free Flanks (without All). As is clear from the figure, when the flux of the present invention was used, the S removal rate was improved by 11 to 21 points compared to the conventional method. FIG. 2 is a graph showing the relationship between the amount of 5olAJ (%) and the amount of O (ppm) in the finished product. As is clear from the graph, if 5olA 12 in the molten steel is set to 0.020% or more, the zero amount can be reduced to 60 ppm without grooves. Figure 3 is I? H reflux time [minutes]: 20 minutes, 40 minutes, 6
It is a graph showing the change in on (ppm) when it changes from 0 minutes. According to this I? l + perfusion time 6
It can be seen that the longer the time is set to 0 minutes or more, the more the O amount is reduced. [Effects of the Invention] As detailed above, in the method for producing duplex stainless steel of the present invention, a flux containing 5% or more of All is used. Since desulfurization is carried out by pouring into the 8 steel stream, stable desulfurization is performed outside the furnace without melting the refractories inside the furnace, and the S removal rate is improved compared to the conventional method. Also, A7! so that the proportion of AN in the molten steel after desulfurization is 0.020% or more! is added and refluxed for 60 minutes or more in an R11 vacuum refining device to perform deoxidation, which has the excellent effect of reducing the amount of O in the steel compared to the conventional method.
第１図は本発明方法の脱Ｓフランクス（ｌ添加）及び従
来方法の脱Ｓフランクス（＾ｌなし）の脱Ｓ率を示すグ
ラフ、第２図は成品の５ｏｌＡ Ａ量〔％〕とＯ量（ｐ
ｐｍ ）との関係を示すグラフ、第３図はＲＨ環流時間
を変化させた場合の０ｆｆｌ （ｐｐｍ ）の変化を示
すグラフ、 第４図は２相系ステンレス鋼における酸素
含有量と孔食発生温度との関係を示すグラフ、第５図は
２相系ステンレス鋼における硫黄含有量と成品を熱間で
加工した場合のクリープ試験の絞り率との関係を示すグ
ラフである。Figure 1 is a graph showing the S removal rate of the S-free flanks of the present invention method (addition of 1) and the conventional method of S-free flanks (without ^L), and Figure 2 is a graph showing the 5olA A content [%] and O content of the product. (p
Figure 3 is a graph showing the change in 0ffl (ppm) when the RH reflux time is changed. Figure 4 is the graph showing the relationship between oxygen content and pitting corrosion occurrence temperature in two-phase stainless steel. FIG. 5 is a graph showing the relationship between the sulfur content in two-phase stainless steel and the reduction ratio in the creep test when the product is hot worked.
Claims (1)
入することにより脱硫処理を行い、次いで溶鋼中のＡｌ
の割合が０．０２０％以上となるようにＡｌを添加し、
ＲＨ真空精錬装置により環流することにより脱酸処理を
行うことを特徴とする２相系ステンレス鋼の溶製方法。1. Desulfurization treatment is performed by pouring flux containing 5% or more of Al into the molten steel flow, and then the Al in the molten steel is removed.
Al is added so that the ratio of is 0.020% or more,
A method for producing two-phase stainless steel, characterized in that deoxidation treatment is performed by refluxing with an RH vacuum refining device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1247485A JPH0696732B2 (en) | 1989-09-22 | 1989-09-22 | Method of melting duplex stainless steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1247485A JPH0696732B2 (en) | 1989-09-22 | 1989-09-22 | Method of melting duplex stainless steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03107411A true JPH03107411A (en) | 1991-05-07 |
| JPH0696732B2 JPH0696732B2 (en) | 1994-11-30 |
Family
ID=17164166
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1247485A Expired - Lifetime JPH0696732B2 (en) | 1989-09-22 | 1989-09-22 | Method of melting duplex stainless steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0696732B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011066394A (en) * | 2009-08-18 | 2011-03-31 | Mitsubishi Electric Corp | Light source device, and method of producing the same |
| CN102952923A (en) * | 2012-11-27 | 2013-03-06 | 南京钢铁股份有限公司 | Process for smelting aluminum containing steel through calcium carbide deoxidation |
-
1989
- 1989-09-22 JP JP1247485A patent/JPH0696732B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011066394A (en) * | 2009-08-18 | 2011-03-31 | Mitsubishi Electric Corp | Light source device, and method of producing the same |
| US8733995B2 (en) | 2009-08-18 | 2014-05-27 | Mitsubishi Electric Corporation | Light source device with reduced optical part clouding |
| CN102952923A (en) * | 2012-11-27 | 2013-03-06 | 南京钢铁股份有限公司 | Process for smelting aluminum containing steel through calcium carbide deoxidation |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0696732B2 (en) | 1994-11-30 |
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