JP2000001759A - Austenitic stainless steel good in surface property and excellent in corrosion resistance - Google Patents
Austenitic stainless steel good in surface property and excellent in corrosion resistanceInfo
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- JP2000001759A JP2000001759A JP17188198A JP17188198A JP2000001759A JP 2000001759 A JP2000001759 A JP 2000001759A JP 17188198 A JP17188198 A JP 17188198A JP 17188198 A JP17188198 A JP 17188198A JP 2000001759 A JP2000001759 A JP 2000001759A
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- oxide
- corrosion resistance
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- steel
- stainless steel
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、表面性状が良好
で耐食性に優れたオーステナイト系ステンレス鋼に関
し、とくに鋼中に含まれる酸化物系介在物の組成を改質
することによって諸特性の有利な改善を図ったものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an austenitic stainless steel having good surface properties and excellent corrosion resistance, and more particularly to an austenitic stainless steel having advantageous properties by modifying the composition of oxide inclusions contained in the steel. It is an improvement.
【０００２】[0002]
【従来の技術】オーステナイト系ステンレス鋼は、高温
強度が高く、熱間での延性が乏しいこと、さらに耐酸化
性がフェライト系ステンレス鋼に比べると劣っているこ
とから、熱延工程のスラブ加熱時に粒界酸化が生じ易
く、その部分で熱間加工時に割れが発生し易いというと
ころに問題があった。2. Description of the Related Art Austenitic stainless steel has high strength at high temperatures, poor hot ductility, and inferior oxidation resistance to ferritic stainless steel. There is a problem in that grain boundary oxidation is apt to occur, and cracks are likely to occur at that portion during hot working.
【０００３】上記の問題に対しては、AlやTi等、酸素と
の化学的親和力の大きい元素の積極的な添加が有効であ
ることが知られている。なお、一般に、溶鋼へのTi添加
は、その歩留り向上を目的として、予めAlで脱酸して実
施される。しかしながら、AlやTiを積極的に添加する
と、溶製後の連続鋳造時にこれら元素の酸化物が浸漬ノ
ズルの内壁に付着して詰まりが発生するという、製造
上、大きな問題があった。[0003] It is known that the active addition of an element having a high chemical affinity with oxygen, such as Al or Ti, is effective against the above-mentioned problems. In general, addition of Ti to molten steel is performed by previously deoxidizing with Al for the purpose of improving the yield. However, when Al or Ti is positively added, there is a serious problem in production that oxides of these elements adhere to the inner wall of the immersion nozzle and cause clogging during continuous casting after smelting.
【０００４】従って、浸漬ノズルの閉塞防止策について
は、従来から種々の提案がなされていて、例えば特開平
８−144021号公報や特開平８−260106号公報には、酸化
物系介在物を Al2O3−TiO2−CaＯ系とし、低融点化する
ことによって、ノズル詰まりを防止する技術が開示され
ている。しかしながら、この技術では、介在物としてCa
Ｓが生成し易く、このCaＳが起点となって錆が発生し易
いため、耐食性が劣化するという問題があり、低Ｓ化が
必要となる。しかも、基本的にAl脱酸技術であるため、
冷延板においてヘゲ状の表面欠陥が免れ得ないという根
本的な問題を残していた。Therefore, various measures have been proposed for preventing the clogging of the immersion nozzle. For example, Japanese Patent Application Laid-Open Nos. 8-144012 and 8-260106 disclose oxide-based inclusions. There is disclosed a technique of preventing nozzle clogging by using a 2 O 3 —TiO 2 —CaO system and lowering the melting point. However, in this technique, Ca is used as an inclusion.
Since S is easily generated and rust is easily generated from this CaS as a starting point, there is a problem that corrosion resistance is deteriorated, and it is necessary to reduce S. And because it is basically Al deoxidation technology,
There remains a fundamental problem that barbed surface defects cannot be avoided in the cold rolled sheet.
【０００５】また、脱酸生成物である Al2O3は、溶製段
階で凝集・クラスター化するため、これが溶鋼中に含ま
れていると、上記したようなノズル閉塞を招くだけでな
く、製品板表面に圧延方向に沿ったへげ状欠陥が発生す
るという問題があった。この問題に対して、特開平４−
99151 号公報では、Tiを添加したフェライト系ステンレ
ス鋼において、Al量の厳しい制限（≦0.002 wt％）と酸
素量の制限（≦0.005 wt％）によって、冷延板の表面品
質を向上させる技術を提案している。この技術によれ
ば、酸素量を規制し Al2O3の生成を抑制しているため、
Al2O3が凝集・クラスター化して発生するヘゲ状の表面
欠陥は著しく低減するものの、TiO2起因のヘゲ状欠陥が
発生するという問題があった。Further, Al 2 O 3, which is a deoxidation product, is agglomerated and clustered in the smelting stage. Therefore, if it is contained in the molten steel, not only the above-described nozzle blockage will occur, There is a problem that a bar-like defect along the rolling direction occurs on the surface of the product plate. To solve this problem,
Japanese Patent No. 99151 discloses a technology for improving the surface quality of cold-rolled sheets by restricting the amount of Al (≦ 0.002 wt%) and the amount of oxygen (≦ 0.005 wt%) in Ti-added ferritic stainless steel. is suggesting. According to this technology, since the amount of oxygen is regulated and the production of Al 2 O 3 is suppressed,
Although barge-like surface defects generated by aggregation and clustering of Al 2 O 3 are remarkably reduced, there is a problem that barium-like defects caused by TiO 2 are generated.
【０００６】[0006]
【発明が解決しようとする課題】この発明は、上記の実
情に鑑み開発されたもので、上述したような従来の問題
を全て解決した、表面性状が良好で耐食性に優れたオー
ステナイト系ステンレス鋼を提案することを目的とす
る。すなわち、この発明における課題は次のとおりであ
る。 (1) 製造時の連続鋳造時にノズル詰まりが無く、製造性
がよいこと。 (2) ヘゲ状表面欠陥がなく表面性状に優れること。 (3) 熱延時の割れに伴うへげ状欠陥がないこと。 (4) 耐食性に優れること。SUMMARY OF THE INVENTION The present invention has been developed in view of the above circumstances, and has been developed to provide an austenitic stainless steel having good surface properties and excellent corrosion resistance, which has solved all the conventional problems as described above. The purpose is to propose. That is, the subject in this invention is as follows. (1) No nozzle clogging during continuous casting during production and good productivity. (2) Excellent surface properties without barbed surface defects. (3) There should be no bald defects due to cracks during hot rolling. (4) Excellent corrosion resistance.
【０００７】[0007]
【課題を解決するための手段】さて、発明者らは、上記
の目的を達成すべく、鋭意研究を重ねた結果、鋼材の成
分組成を適切に調整すると共に、鋼中に含まれる酸化物
系介在物の組成を適正に改質することが、所期した目的
の達成に関し極めて有効であること、また酸化物系介在
物を所望組成に安定して改質するには、鋼成分のうち脱
酸剤として作用する成分の添加順序が極めて重要である
ことの知見を得た。この発明は、上記の知見に立脚する
ものである。Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve the above object, and as a result, have appropriately adjusted the component composition of the steel material and obtained the oxide-based material contained in the steel. Appropriately modifying the composition of inclusions is extremely effective in achieving the intended purpose. To stably modify oxide-based inclusions to the desired composition, it is necessary to remove the steel component. It has been found that the order of addition of components acting as an acid agent is extremely important. The present invention is based on the above findings.
【０００８】すなわち、この発明の要旨構成は次のとお
りである。 １．Ｃ：0.15wt％以下、 Si：1.0 wt％以下、 Mn：2.0 wt％以下、 Cr：15〜30wt％、 Ni：５〜30wt％、 Ｐ：0.05wt％以下、 Ｓ：0.015 wt％以下、 Ｎ：0.15wt％以下、 Al：0.005 wt％以下、 Ｏ：0.01wt％以下、 Ti：0.015 〜0.4 wt％、Ca：0.0005〜0.0050wt％ を含有し、残部は実質的にFeの組成になり、鋼中の脱酸
生成物に起因した酸化物系介在物の組成が、Ti酸化物：
20〜90wt％、 Al2O3：50wt％以下およびCaＯ：５〜50wt
％の範囲を満足することを特徴とする表面性状が良好で
耐食性に優れたオーステナイト系ステンレス鋼。That is, the gist configuration of the present invention is as follows. 1. C: 0.15 wt% or less, Si: 1.0 wt% or less, Mn: 2.0 wt% or less, Cr: 15 to 30 wt%, Ni: 5 to 30 wt%, P: 0.05 wt% or less, S: 0.015 wt% or less, N : 0.15 wt% or less, Al: 0.005 wt% or less, O: 0.01 wt% or less, Ti: 0.015 to 0.4 wt%, Ca: 0.0005 to 0.0050 wt%, the balance being substantially Fe composition, The composition of oxide-based inclusions caused by deoxidation products in steel is Ti oxide:
20~90wt%, Al 2 O 3: 50wt% or less, and CaO: 5-50 wt
% Austenitic stainless steel excellent in surface properties and excellent in corrosion resistance.
【０００９】２．上記１において、鋼組成が、さらに Mo：0.05〜6.0 wt％ を含有する組成になることを特徴とする表面性状が良好
で耐食性に優れたオーステナイト系ステンレス鋼。[0009] 2. 2. The austenitic stainless steel according to the above item 1, wherein the steel composition further comprises Mo: 0.05 to 6.0 wt%.
【００１０】３．上記１または２において、鋼組成が、
さらに Nb：0.01〜0.08wt％、 Ｖ：0.01〜0.1 wt％、 Ｂ：0.
0002〜0.0030wt％ のうちから選んだ１種または２種以上を含有する組成に
なることを特徴とする表面性状が良好で耐食性に優れた
オーステナイト系ステンレス鋼。[0010] 3. In the above 1 or 2, the steel composition is
Further, Nb: 0.01 to 0.08 wt%, V: 0.01 to 0.1 wt%, B: 0.
An austenitic stainless steel having good surface properties and excellent corrosion resistance, characterized by having a composition containing one or more selected from 0002 to 0.0030 wt%.
【００１１】[0011]
【発明の実施の形態】以下、この発明の基礎となった実
験結果について説明する。実験１ Ｃ：0.022 〜0.091 wt％、Si：0.45〜0.86wt％、Mn：0.
66〜1.22wt％、Cr：18.2〜18.6wt％、Ni：8.3 〜8.8 wt
％、Ｐ：0.021 〜0.037 wt％、Ｓ：0.003 〜0.011 wt
％、Ｎ：0.025 〜0.041 wt％、Ｏ：0.0037〜0.0076wt
％、Ti：0.021 〜0.041 wt％、Ca：0.0006〜0.0022wt％
の成分範囲で、Al量を0.0007wt％から 0.021wt％まで変
化させた鋼を溶製し、連続鋳造後（鋳片サイズ：200 mm
厚×1240mm幅）、鋳片を手入れすることなく熱間圧延し
た。熱間圧延は、スラブ加熱条件：1230℃−50分、粗圧
延７パス、粗圧延仕上げ温度：1060〜1120℃、粗圧延仕
上げ厚：28mm、仕上げ（７スタンド）圧延機出側温度：
900 〜1060℃、仕上げ厚：３mm、コイル巻き取り温度：
590 〜1000℃、で行った。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, experimental results on which the present invention is based will be described. Experiment 1 C: 0.022 to 0.091 wt%, Si: 0.45 to 0.86 wt%, Mn: 0.
66 ~ 1.22wt%, Cr: 18.2 ~ 18.6wt%, Ni: 8.3 ~ 8.8wt
%, P: 0.021 to 0.037 wt%, S: 0.003 to 0.011 wt%
%, N: 0.025 to 0.041 wt%, O: 0.0037 to 0.0076 wt%
%, Ti: 0.021 to 0.041 wt%, Ca: 0.0006 to 0.0022 wt%
In the range of components, the steel with the Al content changed from 0.0007 wt% to 0.021 wt% is melted and continuously cast (slab size: 200 mm
(Thickness x 1240 mm width), and the slab was hot-rolled without care. For hot rolling, slab heating conditions: 1230 ° C-50 minutes, rough rolling 7 passes, rough rolling finishing temperature: 1060-1120 ° C, rough rolling finished thickness: 28 mm, finishing (7 stand) rolling mill exit side temperature:
900-1060 ° C, Finish thickness: 3mm, Coil winding temperature:
590-1000 ° C.
【００１２】ついで、熱延コイルを1100℃で連続焼鈍し
たのち、酸洗を施してから、コイル全長にわたって表面
観察を行い、へげ状欠陥の単位面積当たりの平均個数を
求めた。得られた結果を、鋼中Al量との関係で、図１に
示す。なお、観察されたへげ状欠陥はいずれも幅が 0.4
〜3.0 mm程度、長さは30〜500mm 程度であった。図１か
ら明らかなように、Al量が 0.005wt％を超えるとへげ状
欠陥が発生し始めることが判る。これらのヘゲ状欠陥部
を分析したところ Al2O3が検出された。従って、かよう
なヘゲ状欠陥は、鋳込み時に生成した脱酸生成物である
Al2O3が凝集し、熱延時に圧延方向に分断されてできた
ものと考えられる。Next, after the hot-rolled coil was continuously annealed at 1100 ° C., it was pickled, and then the surface was observed over the entire length of the coil to determine the average number of bary defects per unit area. FIG. 1 shows the obtained results in relation to the Al content in the steel. The width of each of the observed barbed defects was 0.4
The length was about 3.0 mm and the length was about 30 to 500 mm. As is clear from FIG. 1, it can be seen that when the amount of Al exceeds 0.005 wt%, a bald defect starts to occur. When these barbed defects were analyzed, Al 2 O 3 was detected. Therefore, such barbed defects are deoxidized products generated during casting.
It is considered that Al 2 O 3 was agglomerated and was divided in the rolling direction during hot rolling.
【００１３】実験２ Ｃ：0.022 〜0.091 wt％、Si：0.45〜0.86wt％、Mn：0.
66〜1.22wt％、Cr：18.2〜18.6wt％、Ni：8.3 〜8.7 wt
％、Ｐ：0.021 〜0.037 wt％、Ｓ：0.003 〜0.011 wt
％、Ｎ：0.025 〜0.041 wt％、Ｏ：0.0037〜0.0076wt
％、Ti：0.021 〜0.041 wt％、Ca：0.0006〜0.0022wt％
の成分範囲で、Al量を0.0007wt％から0.021wt％まで変
化させた鋼を溶製し、連続鋳造後（鋳片サイズ：200mm
厚×1240mm幅）、鋳片を手入れすることなく熱間圧延し
た。熱間圧延は、スラブ加熱条件：1260℃−50分、粗圧
延７パス、粗圧延仕上げ温度：1060〜1120℃、粗圧延仕
上げ厚：28mm、仕上げ（７スタンド）圧延機出側温度：
900 〜1060℃、仕上げ厚：3mm、コイル巻き取り温度：5
90 〜1000℃、で行った。得られた熱延コイルを、1100
℃で連続焼鈍し、酸洗後、冷間圧延により板厚：0.8 mm
に仕上げたのち、1080〜1130℃で連続焼鈍後、酸洗し
て、冷延焼鈍板とした。 Experiment 2 C: 0.022 to 0.091 wt%, Si: 0.45 to 0.86 wt%, Mn: 0.
66 to 1.22 wt%, Cr: 18.2 to 18.6 wt%, Ni: 8.3 to 8.7 wt%
%, P: 0.021 to 0.037 wt%, S: 0.003 to 0.011 wt%
%, N: 0.025 to 0.041 wt%, O: 0.0037 to 0.0076 wt%
%, Ti: 0.021 to 0.041 wt%, Ca: 0.0006 to 0.0022 wt%
In the range of components, the steel with the Al content changed from 0.0007 wt% to 0.021 wt% is melted and continuously cast (slab size: 200 mm
(Thickness x 1240 mm width), and the slab was hot-rolled without care. For hot rolling, slab heating conditions: 1260 ° C-50 minutes, rough rolling 7 passes, rough rolling finishing temperature: 1060-1120 ° C, rough rolling finished thickness: 28 mm, finishing (7 stand) rolling mill exit side temperature:
900 ~ 1060 ℃, Finish thickness: 3mm, Coil winding temperature: 5
90-1000 ° C. The obtained hot rolled coil was
Annealed continuously at ℃, pickled and then cold rolled to a thickness of 0.8 mm
Then, after continuous annealing at 1080 to 1130 ° C., it was pickled to obtain a cold-rolled annealed plate.
【００１４】かくして得られた冷延焼鈍板の全長にわた
って表面観察を行い、へげ状欠陥の単位面積当たりの平
均個数を求めた。また、得られた冷延焼鈍板に存在する
酸化物系介在物の定量をブローム法によって行った。得
られた結果を、介在物中の Al2O3量で整理して図２に示
す。同図に示したとおり、酸化物系介在物中の Al2O3量
が50wt％を超えるとヘゲ状欠陥が急激に発生し始めるこ
とが判る。これに対し、 Al2O3量が50wt％以下ではヘゲ
状欠陥の発生は少なく、特に Al2O3量が20wt％以下の場
合には、ヘゲ状欠陥の発生はほとんど認められなかっ
た。なお、観察されたへげ状欠陥はいずれも、幅が0.2
〜2.0 mm程度、長さは80〜1000mm程度であった。The surface of the thus obtained cold-rolled annealed sheet was observed over its entire length, and the average number of bary defects per unit area was determined. In addition, the quantification of oxide-based inclusions present in the obtained cold-rolled annealed sheet was performed by the Brome method. The obtained results are shown in FIG. 2 arranged by the amount of Al 2 O 3 in the inclusions. As shown in the figure, it can be seen that when the amount of Al 2 O 3 in the oxide-based inclusions exceeds 50% by weight, barge-like defects begin to rapidly occur. On the other hand, when the Al 2 O 3 content is 50 wt% or less, the occurrence of barbed defects is small, and particularly when the Al 2 O 3 content is 20 wt% or less, almost no barbed defects are observed. . The width of each of the observed barbed defects was 0.2 mm.
The length was about 2.0 mm and the length was about 80 to 1000 mm.
【００１５】実験３ Ｃ：0.022 〜0.091 wt％、Si：0.45〜0.86wt％、Mn：0.
66〜1.22wt％、Cr：18.2〜18.6wt％、Ni：8.3 〜8.8 wt
％、Ｐ：0.021 〜0.037 wt％、Ｓ：0.003 〜0.011 wt
％、Ｎ：0.025 〜0.041 wt％、Ｏ：0.0037〜0.0083wt
％、Ti：0.015 〜0.27wt％、Ca：0.0006〜0.0022wt％の
成分範囲で、Al量を0.0007wt％から0.0044wt％まで変化
させた鋼を溶製し、連続鋳造後（鋳片サイズ：200mm 厚
×1240mm幅）、鋳片を手入れすることなく熱間圧延し
た。熱間圧延は、スラブ加熱条件：1260℃−50分、粗圧
延７パス、粗圧延仕上げ温度：1060〜1120℃、粗圧延仕
上げ厚：28mm、仕上げ（７スタンド）圧延機出側温度：
900 〜1060℃、仕上げ厚：３mm、コイル巻き取り温度：
700 〜1000℃、で行った。ついで、得られた熱延コイル
を1100℃で連続焼鈍し、酸洗後、冷間圧延によって板
厚：0.8 mmに仕上げたのち、1080〜1130℃で連続焼鈍
後、酸洗して、冷延焼鈍板とした。 Experiment 3 C: 0.022 to 0.091 wt%, Si: 0.45 to 0.86 wt%, Mn: 0.
66 ~ 1.22wt%, Cr: 18.2 ~ 18.6wt%, Ni: 8.3 ~ 8.8wt
%, P: 0.021 to 0.037 wt%, S: 0.003 to 0.011 wt%
%, N: 0.025 to 0.041 wt%, O: 0.0037 to 0.0083 wt%
%, Ti: 0.015 to 0.27 wt%, Ca: 0.0006 to 0.0022 wt%, the steel with the Al content changed from 0.0007 wt% to 0.0044 wt% is melted and continuously cast (slab size: The slab was hot-rolled without care, with a thickness of 200 mm x 1240 mm width. For hot rolling, slab heating conditions: 1260 ° C-50 minutes, rough rolling 7 passes, rough rolling finishing temperature: 1060-1120 ° C, rough rolling finished thickness: 28 mm, finishing (7 stand) rolling mill exit side temperature:
900-1060 ° C, Finish thickness: 3mm, Coil winding temperature:
700-1000 ° C. Then, the obtained hot-rolled coil was continuously annealed at 1100 ° C, pickled, finished to a sheet thickness of 0.8 mm by cold rolling, continuously annealed at 1080 to 1130 ° C, pickled, and cold-rolled. An annealed plate was used.
【００１６】かくして得られた冷延焼鈍板の試験片表面
をエメリー＃600 研磨し、塩水噴霧試験（JIS-Z-2371準
拠）を50℃で４時間行い、錆の個数をカウントした。ま
た、連続鋳造後の浸漬ノズルを回収し、ノズル閉塞率を
測定した。さらに、冷延焼鈍板に存在する酸化物系介在
物の定量をブローム法により行った。得られた結果を、
酸化物系介在物中のTi酸化物量で整理して図３に示す。
同図から明らかなように、介在物中のTi酸化物量が20〜
90wt％の範囲にあれば、連鋳時のノズル閉塞がなく、ま
た耐食性も良好であることが判る。The surface of the test piece of the cold-rolled annealed sheet thus obtained was polished with Emery # 600, and a salt spray test (based on JIS-Z-2371) was performed at 50 ° C. for 4 hours, and the number of rusts was counted. Further, the immersion nozzle after the continuous casting was recovered, and the nozzle closing rate was measured. Furthermore, the quantification of oxide-based inclusions present in the cold-rolled annealed sheet was performed by the Brome method. The obtained result is
FIG. 3 summarizes the amounts of Ti oxide in the oxide-based inclusions.
As is clear from the figure, the amount of Ti oxide in the inclusions was 20 to
It can be seen that when the content is in the range of 90 wt%, there is no nozzle blockage during continuous casting and the corrosion resistance is good.
【００１７】実験４ Ｃ：0.022 〜0.091 wt％、Si：0.45〜0.86wt％、Mn：0.
66〜1.22wt％、Cr：18.2〜18.6wt％、Ni：8.3 〜9.5 wt
％、Ｐ：0.021 〜0.037 wt％、Ｓ：0.003 〜0.011 wt
％、Ｎ：0.025 〜0.041 wt％、Ｏ：0.0037〜0.0083wt
％、Ti：0.026 〜0.033 wt％、Al：0.0002〜0.0033wt％
の成分範囲で、Ca量を0.0002wt％から0.0059wt％まで変
化させた鋼を溶製し、連続鋳造後（鋳片サイズ：200mm
厚×1240mm幅）、鋳片を手入れすることなく熱間圧延し
た。熱間圧延は、スラブ加熱条件：1260℃−50分、粗圧
延７パス、粗圧延仕上げ温度：1060〜1120℃、粗圧延仕
上げ厚：28mm、仕上げ（７スタンド）圧延機出側温度：
900 〜1060℃、仕上げ厚：３mm、コイル巻き取り温度：
700 〜1000℃、で行った。ついで、得られた熱延コイル
を1100℃で連続焼鈍し、酸洗後、冷間圧延によって板
厚：0.8 mmに仕上げたのち、1080〜1130℃で連続焼鈍
後、酸洗して、冷延焼鈍板とした。 Experiment 4 C: 0.022 to 0.091 wt%, Si: 0.45 to 0.86 wt%, Mn: 0.
66 ~ 1.22wt%, Cr: 18.2 ~ 18.6wt%, Ni: 8.3 ~ 9.5wt
%, P: 0.021 to 0.037 wt%, S: 0.003 to 0.011 wt%
%, N: 0.025 to 0.041 wt%, O: 0.0037 to 0.0083 wt%
%, Ti: 0.026 to 0.033 wt%, Al: 0.0002 to 0.0033 wt%
In a range of components, the steel with the Ca content changed from 0.0002 wt% to 0.0059 wt% is melted and continuously cast (slab size: 200 mm
(Thickness x 1240 mm width), and the slab was hot-rolled without care. For hot rolling, slab heating conditions: 1260 ° C-50 minutes, rough rolling 7 passes, rough rolling finishing temperature: 1060-1120 ° C, rough rolling finished thickness: 28 mm, finishing (7 stand) rolling mill exit side temperature:
900-1060 ° C, Finish thickness: 3mm, Coil winding temperature:
700-1000 ° C. Then, the obtained hot-rolled coil was continuously annealed at 1100 ° C, pickled, finished to a sheet thickness of 0.8 mm by cold rolling, continuously annealed at 1080 to 1130 ° C, pickled, and cold-rolled. An annealed plate was used.
【００１８】かくして得られた冷延焼鈍板の試験片表面
をエメリー＃600 研磨し、塩水噴霧試験（JIS-Z-2371準
拠）を50℃で４時間行い、錆の個数をカウントした。ま
た、連続鋳造後の浸漬ノズルを回収し、ノズル閉塞率を
測定した。さらに、冷延焼鈍板に存在する酸化物系介在
物の定量をブローム法により行った。得られた結果を、
酸化物系介在物中のCaＯ量で整理して図４に示す。同図
から明らかなように、介在物中のCaＯ量が５〜50wt％の
範囲にあれば、連鋳時のノズル閉塞がなく、また耐食性
も良好であることが判る。The surface of the test piece of the cold-rolled annealed plate thus obtained was polished with Emery # 600, and a salt spray test (based on JIS-Z-2371) was performed at 50 ° C. for 4 hours, and the number of rusts was counted. Further, the immersion nozzle after the continuous casting was recovered, and the nozzle closing rate was measured. Furthermore, the quantification of oxide-based inclusions present in the cold-rolled annealed sheet was performed by the Brome method. The obtained result is
FIG. 4 summarizes the amounts of CaO in the oxide-based inclusions. As is clear from the figure, when the CaO content in the inclusions is in the range of 5 to 50 wt%, there is no nozzle blockage during continuous casting and good corrosion resistance.
【００１９】実験５ Ｃ：0.022 〜0.091 wt％、Si：0.45〜0.86wt％、Mn：0.
66〜1.22wt％、Cr：18.2〜18.6wt％、Ni：8.3 〜9.5 wt
％、Ｐ：0.021 〜0.037 wt％、Ｓ：0.001 〜0.021 wt
％、Ｎ：0.025 〜0.041 wt％、Ｏ：0.0037〜0.0083wt
％、Ti：0.026 〜0.038 wt％、Al：0.0018〜0.0033wt％
の組成範囲で、しかも酸化物系介在物中のAl 2O3 量が５
〜20wt％の水準と55〜65wt％の水準の２水準について、
Ca量を0.0002〜0.0058wt％の範囲で変化させた鋼を溶製
し、連続鋳造後（鋳片サイズ：200mm厚×1240mm幅）、
鋳片を手入れすることなく熱間圧延した。熱間圧延は、
スラブ加熱条件：1260℃−50分、粗圧延７パス、粗圧延
仕上げ温度：1060〜1120℃、粗圧延仕上げ厚：28mm、仕
上げ（７スタンド）圧延機出側温度：900 〜1060℃、仕
上げ厚：3mm 、コイル巻き取り温度：700 〜1000℃、で
行った。ついで、得られた熱延コイルを1100℃で連続焼
鈍し、酸洗後、冷間圧延によって板厚：0.8 mmに仕上げ
たのち、1080〜1130℃で連続焼鈍後、酸洗して、冷延焼
鈍板とした。[0019]Experiment 5 C: 0.022 to 0.091 wt%, Si: 0.45 to 0.86 wt%, Mn: 0.
66 ~ 1.22wt%, Cr: 18.2 ~ 18.6wt%, Ni: 8.3 ~ 9.5wt
%, P: 0.021 to 0.037 wt%, S: 0.001 to 0.021 wt%
%, N: 0.025 to 0.041 wt%, O: 0.0037 to 0.0083 wt%
%, Ti: 0.026 to 0.038 wt%, Al: 0.0018 to 0.0033 wt%
Al composition in the oxide range TwoOThreeQuantity 5
About two levels of ~ 20wt% level and 55 ~ 65wt% level,
Molten steel with Ca content varied from 0.0002 to 0.0058 wt%
After continuous casting (slab size: 200mm thickness x 1240mm width)
The slab was hot rolled without care. Hot rolling is
Slab heating conditions: 1260 ° C-50 minutes, rough rolling 7 passes, rough rolling
Finishing temperature: 1060 ~ 1120 ℃, Rough rolling finish thickness: 28mm, finishing
Raising (7 stands) rolling mill outlet temperature: 900 to 1060 ° C, finish
Thickness: 3mm, coil winding temperature: 700 ~ 1000 ℃,
went. Then, the obtained hot rolled coil was continuously fired at 1100 ° C.
After dulling, pickling, and cold rolling to finish to a thickness of 0.8 mm
After that, after continuous annealing at 1080-1130 ° C, pickling and cold rolling
It was a blunt plate.
【００２０】かくして得られた冷延焼鈍板の試験片表面
をエメリー＃600 研磨し、塩水噴霧試験（JIS-Z-2371準
拠）を50℃で４時間行い、錆の個数をカウントした。こ
こで、発錆個数が dm2当たり５個以下の場合をOK、20個
以上の場合をNGとした。図５に、それぞれの Al2O3水準
に関して行った耐食性評価結果を、Ｓ量とCa量で整理し
て示す。同図に示したとおり、酸化物系介在物中の Al2
O3量が50wt％以下の水準では、耐食性が良好なＳ、Ca範
囲は広範囲であるのに対し、 Al2O3量が55〜65wt％の水
準ではその範囲は非常に狭く、耐食性の面から低Ｓ化が
必要不可欠であることが判る。The surface of the test piece of the cold-rolled annealed plate thus obtained was polished with Emery # 600, and a salt spray test (according to JIS-Z-2371) was performed at 50 ° C. for 4 hours, and the number of rusts was counted. Here, the case where the number of rusting was 5 or less per dm 2 was OK, and the case where the number was 20 or more was NG. FIG. 5 shows the results of the corrosion resistance evaluation performed for each of the Al 2 O 3 levels, organized in terms of the amounts of S and Ca. As shown in the figure, Al 2 in oxide-based inclusions
When the O 3 content is 50 wt% or less, the range of S and Ca having good corrosion resistance is wide, whereas when the Al 2 O 3 content is 55 to 65 wt%, the range is very narrow, and the corrosion resistance is low. From this, it is understood that the reduction of S is indispensable.
【００２１】以上、述べたとおり、この発明で所期した
目的を達成するためには、鋼中Al量を0.005 wt％以下に
抑制すると共に、酸化物系介在物の組成を Al2O3：50wt
％以下、Ti酸化物：20〜90wt％およびCaＯ：５〜50wt％
の範囲に制限することが重要である。しかしながら、酸
化物系介在物の組成を上記の範囲に制御するのは容易で
はなく、介在物組成が上記の範囲になるように鋼組成を
成分調整したつもりでも、介在物組成がばらつきが大き
く、必ずしも所望の組成範囲におさまるわけではないこ
とが判明した。As described above, in order to achieve the desired object of the present invention, the content of Al in steel is suppressed to 0.005 wt% or less, and the composition of oxide-based inclusions is changed to Al 2 O 3 : 50wt
%, Ti oxide: 20-90 wt% and CaO: 5-50 wt%
It is important to limit to the range. However, it is not easy to control the composition of the oxide-based inclusions in the above range, and even if the steel composition is intended to be adjusted so that the inclusion composition is in the above range, the inclusion composition has a large variation, It has been found that the composition does not always fall within the desired composition range.
【００２２】そこで、発明者らは、この点について、さ
らに研究を重ねた結果、酸化物系介在物の組成を上記の
範囲に安定して制御するためには、脱酸剤成分であるA
l、TiおよびCaの添加量もさることながら、これらの成
分を添加する順序が極めて重要であることが判明した。
すなわち、まず、少量のAl添加またはSi添加によって予
備的脱酸を行った後、比較的多量のTiを添加してTi脱酸
を行うと、Al脱酸により生成した Al2O3またはSi脱酸に
より生成したSiO2をTi酸化物が包むような形態のTi酸化
物となり、このような形態のTi酸化物とした上で適量の
Caを添加してやると、所望組成の酸化物系介在物が安定
して得られることが究明されたのである。ここに、上記
のようにして得られた酸化物系介在物は、低融点である
ので連続鋳造時にノズル詰まりを生じることがなく、ま
た、その大きさは５〜20μm 程度にすぎないので製品板
においてクラスター状介在物に起因した表面欠陥が発生
することもない。しかも、この酸化物系介在物の周りに
はCaＳが生成することがないので発錆のおそれもない。Therefore, the inventors have further studied on this point, and as a result, in order to stably control the composition of the oxide-based inclusions within the above range, the deoxidizing agent component A
It turned out that the order in which these components were added was extremely important, as well as the amounts of l, Ti and Ca added.
That is, first, a preliminary deoxidation is performed by adding a small amount of Al or Si, and then a relatively large amount of Ti is added to perform Ti deoxidation, whereby Al 2 O 3 or Si generated by Al deoxidation is removed. It becomes a Ti oxide in a form that the Ti oxide wraps the SiO 2 generated by the acid.
It has been found that when Ca is added, oxide-based inclusions having a desired composition can be stably obtained. Here, the oxide-based inclusions obtained as described above have a low melting point so that nozzle clogging does not occur during continuous casting, and the size is only about 5 to 20 μm. No surface defects due to the cluster-like inclusions are generated. Moreover, since CaS is not generated around the oxide-based inclusions, there is no possibility of rusting.
【００２３】この点、鋼の溶製に際し、脱酸剤成分の添
加順序を特に考慮せずに、合金成分を同時に添加した場
合、特に従来のようにAlを比較的多量に添加した場合に
は、Al2O3 が主体の酸化物が生成し易いため、この発明
で所期したような組成の介在物とはならず、その結果、
所望の効果が得られなかったものと考えられる。また、
この発明では、鋼の溶製段階で、ＶＯＤ炉等を用いた強
攪拌を利用するのに対し、従来は、かような溶製手段を
適切に講じていなかったことも、所望の効果が得られな
かった一因と考えられる。[0023] In this regard, when the alloying components are added simultaneously without regard to the order of adding the deoxidizing agent components when smelting steel, especially when a relatively large amount of Al is added as in the prior art. Since an oxide mainly composed of Al 2 O 3 is easily generated, the inclusions do not become inclusions having the composition expected in the present invention.
It is considered that the desired effect was not obtained. Also,
In the present invention, in the step of melting steel, strong stirring using a VOD furnace or the like is used. On the other hand, a desired effect can be obtained because such melting means have not been appropriately taken in the past. It is considered to be one of the reasons for not being able to do so.
【００２４】Ｃ：0.15wt％以下 Ｃは、オーステナイト安定化元素であり、安定してオー
ステナイト相を形成するのに必要な元素である。しかし
ながら、あまりに多量に含有されると延性が低下した
り、耐食性の劣化を招くので、0.15wt％以下に限定し
た。C: 0.15 wt% or less C is an austenite stabilizing element and is an element necessary for stably forming an austenite phase. However, if the content is too large, the ductility is reduced and the corrosion resistance is deteriorated. Therefore, the content is limited to 0.15 wt% or less.
【００２５】Si：1.0 wt％以下 Siは、脱酸のために有用な元素であるが、強力なフェラ
イト安定化元素でもある。従って、過剰の添加はオース
テナイト相を不安定化させ、また延性の低下も招く。従
って、この発明では、1.0 wt％以下で含有させるものと
した。Si: 1.0 wt% or less Si is a useful element for deoxidation, but is also a strong ferrite stabilizing element. Therefore, an excessive addition destabilizes the austenite phase and causes a decrease in ductility. Therefore, in the present invention, the content is set to 1.0 wt% or less.
【００２６】Mn：2.0 wt％以下 Mnは、脱酸のために有効な元素であり、またオーステナ
イト安定化元素でもある。しかしながら、過剰の添加は
耐酸化性や耐食性の低下を招くので、2.0 wt％以下に限
定した。Mn: 2.0 wt% or less Mn is an element effective for deoxidation and is also an austenite stabilizing element. However, excessive addition causes a decrease in oxidation resistance and corrosion resistance, so the content was limited to 2.0 wt% or less.
【００２７】Cr：15〜30wt％ Crは、耐食性を確保する上で必要不可欠な元素であり、
オーステナイト系ステンレス鋼の主要合金元素である。
種々な環境下での耐食性を考慮すると、15wt％以上で十
分な耐食性が得られるので、下限は15wt％に限定した。
一方、30wt％を超えると熱間加工性の著しい低下を招く
ので、上限は30wt％に定めた。Cr: 15 to 30 wt% Cr is an indispensable element for ensuring corrosion resistance.
It is the main alloying element of austenitic stainless steel.
Considering the corrosion resistance under various environments, sufficient corrosion resistance can be obtained at 15 wt% or more, so the lower limit was limited to 15 wt%.
On the other hand, if it exceeds 30 wt%, the hot workability will be significantly reduced, so the upper limit is set to 30 wt%.
【００２８】Ｐ：0.05wt％以下 Ｐは、耐食性とくに耐粒界腐食性に有害な元素であり、
含有量が0.05wt％を超えるとその弊害が顕著となるの
で、0.05wt％に制限した。P: 0.05 wt% or less P is an element harmful to corrosion resistance, particularly intergranular corrosion resistance,
If the content exceeds 0.05 wt%, the adverse effects become remarkable, so the content was limited to 0.05 wt%.
【００２９】Ｓ：0.015 wt％以下 前述したように、Ｓは耐食性を低下させる元素である。
とりわけ、この発明のようにCa添加を行う場合には水溶
性であるCaＳを生じ易い。添加するCa量にも依存する
が、この発明の主眼である酸化物系介在物組成をコント
ロールしても、Ｓ量が 0.015wt％を超えると耐食性の劣
化が生じ易くなるので、Ｓ量は 0.015wt％以下に制限し
た。S: 0.015 wt% or less As described above, S is an element that lowers corrosion resistance.
In particular, when Ca is added as in the present invention, water-soluble CaS is easily generated. Although depending on the amount of Ca added, even if the composition of the oxide-based inclusions, which is the main feature of the present invention, is controlled, if the amount of S exceeds 0.015 wt%, deterioration of corrosion resistance is likely to occur. It was limited to wt% or less.
【００３０】Ｎ：0.15wt％以下 Ｎも、Ｃと同様、オーステナイト安定化元素であり、安
定的にオーステナイト相を得るには必要な元素である。
しかしながら、多量に含有すると延性の低下や耐食性の
劣化を招くので、上限を0.15wt％に定めた。N: 0.15 wt% or less N, like C, is an austenite stabilizing element and is an element necessary for stably obtaining an austenite phase.
However, if contained in a large amount, ductility and corrosion resistance deteriorate, so the upper limit is set to 0.15 wt%.
【００３１】Al：0.005 wt％以下 実験１の結果からも明らかなように、冷延板表面品質の
点から0.005 wt％以下にする必要がある。すなわち、含
有量が 0.005wt％を超えると表面に Al2O3の凝集に起因
したへげ状欠陥が生じる。Al: 0.005 wt% or less As is clear from the results of Experiment 1, it is necessary to make the content 0.005 wt% or less from the viewpoint of the surface quality of the cold-rolled sheet. That is, if the content exceeds 0.005 wt%, a flaky defect due to aggregation of Al 2 O 3 is generated on the surface.
【００３２】Ｏ：0.01wt％以下 酸素は鋼中には全く固溶せず、酸化物として存在する。
かかる介在物は錆や破壊の起点となり易く、特に酸素量
が0.01wt％を超えるとその影響が顕著となるので、Ｏ量
は0.01wt％以下に制限した。O: 0.01 wt% or less Oxygen does not form a solid solution in steel at all and exists as an oxide.
Such inclusions are likely to be a starting point of rust and breakage. Particularly, when the oxygen content exceeds 0.01 wt%, the effect becomes remarkable. Therefore, the O content is limited to 0.01 wt% or less.
【００３３】Ti：0.015 〜0.4 wt％ Tiは、脱酸に有用なだけでなく、熱延工程のスラブ加熱
時における粒界酸化を防止して、熱延割れ起因の欠陥発
生を抑制するのに有効な元素である。しかしながら、含
有量が 0.015wt％に満たないとその添加効果に乏しく、
一方 0.4wt％を超えると延性が低下しはじめるので、Ti
は 0.015〜0.4 wt％の範囲で含有させるものとした。Ti: 0.015 to 0.4 wt% Ti is useful not only for deoxidation but also for preventing grain boundary oxidation at the time of slab heating in the hot rolling process and for suppressing generation of defects due to hot rolling cracks. It is an effective element. However, if the content is less than 0.015 wt%, the effect of the addition is poor,
On the other hand, if the content exceeds 0.4 wt%, the ductility starts to decrease.
Was contained in the range of 0.015 to 0.4 wt%.
【００３４】Ca：0.0005〜0.0050wt％ Caは、この発明に係る酸化物系介在物の融点を効果的に
低下して、連続鋳造時におけるノズル閉塞を防止するの
に極めて有効な元素であり、その効果は0.0005wt％以上
で顕著であるので、下限は0.0005wt％とした。一方、多
量に添加すると脱酸生成物組成をコントロールしても耐
食性の劣化を招き、含有量が0.0050wt％を超えるとその
おそれが顕著になるので、上限は0.0050wt％とした。Ca: 0.0005 to 0.0050 wt% Ca is an element which is extremely effective in effectively lowering the melting point of the oxide-based inclusion according to the present invention and preventing nozzle clogging during continuous casting. Since the effect is remarkable at 0.0005 wt% or more, the lower limit is set to 0.0005 wt%. On the other hand, when added in a large amount, even if the composition of the deoxidized product is controlled, the corrosion resistance is deteriorated, and if the content exceeds 0.0050 wt%, the fear becomes remarkable, so the upper limit was made 0.0050 wt%.
【００３５】以上、基本成分について説明したが、この
発明では、必要応じて次の元素をそれぞれ適宜添加する
ことができる。 Mo：0.05〜6.0 wt％ Moは、耐食性の向上に非常に有効な元素であり、その効
果は0.05wt％以上で顕著になるので、下限は0.05wt％と
した。一方、Moは添加すればするほど耐食性は向上する
が、強力なフェライト安定化元素であるだけでなく、6.
0 wt％を超えると高温で脆弱な金属間化合物を生成し、
靱性を劣化させるので、上限は 6.0wt％とした。The basic components have been described above. In the present invention, the following elements can be appropriately added as needed. Mo: 0.05 to 6.0 wt% Mo is a very effective element for improving corrosion resistance, and its effect becomes significant at 0.05 wt% or more. Therefore, the lower limit is set to 0.05 wt%. On the other hand, the more Mo is added, the better the corrosion resistance, but it is not only a strong ferrite stabilizing element, but also 6.
If it exceeds 0 wt%, it produces brittle intermetallic compounds at high temperatures,
Since the toughness is deteriorated, the upper limit is set to 6.0% by weight.
【００３６】Nb：0.01〜0.08wt％、Ｖ：0.01〜0.1 wt
％、Ｂ：0.0002〜0.0030wt％ Nb、ＶおよびＢはいずれも、結晶粒径の不均一性に起因
して冷延焼鈍板表面に生成し易い縞状の模様発生を防止
するのに極めて有用な元素である。その効果は、Nb：0.
01wt％以上、Ｖ：0.01wt％以上、Ｂ：0.0002％以上の単
独または複合添加で認められるので、下限はそれぞれ0.
01wt％, 0.01wt％, 0.0002wt％に限定した。しかしなが
ら、Nbについては0.08wt％を超えると伸びが低下しはじ
め、またＶについては 0.1wt％を超えると延性が低下し
はじめ、さらにＢについては0.0030wt％を超えると耐粒
界腐食性が低下しはじめるので、それぞれ上限は0.08wt
％、0.1 wt％、0.0030wt％に限定した。Nb: 0.01-0.08 wt%, V: 0.01-0.1 wt%
%, B: 0.0002 to 0.0030 wt% All of Nb, V and B are extremely useful for preventing the occurrence of stripe patterns which are easily formed on the surface of the cold-rolled annealed sheet due to the non-uniformity of the crystal grain size. Element. The effect is Nb: 0.
The lower limit of each is 0.1 wt% or more, V: 0.01 wt% or more, and B: 0.0002% or more.
Limited to 01 wt%, 0.01 wt%, 0.0002 wt%. However, for Nb, the elongation starts to decrease when it exceeds 0.08 wt%, for V, the ductility starts to decrease when it exceeds 0.1 wt%, and for B, the intergranular corrosion resistance decreases when it exceeds 0.0030 wt%. The upper limit is 0.08wt
%, 0.1 wt% and 0.0030 wt%.
【００３７】次に、この発明において、酸化物系介在物
組成を前記の範囲を限定した理由について説明する。 Ti酸化物量：20〜90wt％、 Al2O3：50wt％以下、CaＯ：
５〜50wt％ 酸化物系介在物の組成を上記の範囲にしたところが、こ
の発明の主眼技術である。先に実験２，３，４，５で示
したように、 Al2O3量を50wt％以下、より好ましくは20
wt％以下とすることによって、冷延板で生成するヘゲ状
表面欠陥を防止でき、さらにTi酸化物量を20〜90wt％、
CaＯ量を５〜50wt％とすることによって、連続鋳造時に
おけるノズル詰まりを防止でき、しかも耐食性の劣化も
ない。従って、この発明では、脱酸生成物に起因した酸
化物系介在物の組成について、Ti酸化物：20〜90wt％、
Al2O3：50wt％以下、CaＯ：５〜50wt％の範囲に限定し
たのである。Next, the reason why the composition of the oxide-based inclusions in the present invention is limited to the above range will be described. Ti oxide content: 20~90wt%, Al 2 O 3 : 50wt% or less, CaO:
The main technology of the present invention is that the composition of the oxide-based inclusions is within the above range. As previously shown in Experiments 2, 3, 4, and 5, the amount of Al 2 O 3 was reduced to 50 wt% or less, more preferably 20 wt% or less.
By setting the content to not more than wt%, barbed surface defects generated in the cold rolled sheet can be prevented.
By setting the CaO content to 5 to 50 wt%, nozzle clogging during continuous casting can be prevented, and there is no deterioration in corrosion resistance. Therefore, in the present invention, regarding the composition of the oxide-based inclusions caused by the deoxidation product, Ti oxide: 20 to 90 wt%,
Al 2 O 3 : limited to 50 wt% or less, CaO: limited to 5 to 50 wt%.
【００３８】なお、この発明では、鋼中の全ての介在物
を、上記の組成の複合酸化物とする必要はなく、少なく
とも50％、好ましくは70％以上がかような Al2O3−Ti酸
化物−CaＯ系複合酸化物になっていれば良い。ここに、
その他に生成される酸化物としては、SiO2, MnO, FeOX
およびMgO などが考えられる。In the present invention, it is not necessary that all inclusions in the steel be a composite oxide having the above composition, and at least 50%, preferably 70% or more of Al 2 O 3 —Ti What is necessary is just to be an oxide-CaO-based composite oxide. here,
Other oxides generated include SiO 2 , MnO, FeO X
And MgO.
【００３９】次に、この発明の好適製造方法について説
明する。この発明では、前述したとおり、溶製段階にお
ける脱酸剤成分の添加順序が重要である。すなわち、ま
ず、少量のAlまたはSiを添加して予備的脱酸を行ったの
ち、比較的多量のTiを添加してTi脱酸を行う。このよう
にすると、AlまたはSi脱酸により生成した Al2O3やSiO2
がTi酸化物で包まれたような形態のTi酸化物となるが、
かような形態のTi酸化物の大きさは５〜20μm 程度であ
るので、製品板において巨大のクラスター状介在物に起
因した表面欠陥を有利に防止することができる。しかし
ながら、かかるTi酸化物は、溶鋼中では固相であるた
め、このままでは連続鋳造時に地鉄を取り込んだ形でタ
ンディッシュのノズル内面に付着・堆積して、ノズルの
閉塞を生じるおそれがある。しかしながら、その後にCa
を適量添加してやると、低融点の酸化物となり、それ故
連続鋳造時におけるノズル詰まりが有利に回避されるの
である。しかも、かかる酸化物系介在物の周りにはCaＳ
が生成することがないので発錆も併せて防止できること
は前述したとおりである。Next, a preferred manufacturing method of the present invention will be described. In the present invention, as described above, the order of addition of the deoxidizer component in the melting step is important. That is, first, a small amount of Al or Si is added to perform preliminary deoxidation, and then a relatively large amount of Ti is added to perform Ti deoxidation. In this way, Al 2 O 3 or SiO 2 generated by deoxidation of Al or Si
Is a form of Ti oxide wrapped in Ti oxide,
Since the size of the Ti oxide in such a form is about 5 to 20 μm, it is possible to advantageously prevent surface defects due to huge cluster-like inclusions on the product plate. However, since the Ti oxide is a solid phase in the molten steel, there is a possibility that the titanium oxide may adhere and accumulate on the inner surface of the nozzle of the tundish in a form in which the ground iron is taken in during continuous casting, and the nozzle may be clogged. However, then Ca
When an appropriate amount is added, a low-melting-point oxide is obtained, so that nozzle clogging during continuous casting is advantageously avoided. In addition, around such oxide-based inclusions, CaS
As described above, since rust is not generated, rusting can also be prevented.
【００４０】上記のようにして、所望の鋼組成および介
在物組成に調整した溶鋼は、常法に従って、鋳造、熱間
圧延、冷間圧延および焼鈍処理を施して製品とされる。
ここに、好適な熱延条件、冷延条件および焼鈍条件は次
のとおりである。熱延条件 スラブ加熱温度：1050〜1260℃、粗圧延温度：900 〜11
80℃、粗圧延トータル圧下率：80〜93％、仕上げ圧延温
度：750 〜1000℃、仕上げ圧延出側厚さ：1.5〜７mm、
巻取り温度：400 〜850 ℃。冷延条件 冷間圧延は、タンデムミル、クラスターミルまたはゼン
ジミィアーミルにより圧延できる。総圧下率は45〜95％
程度が好ましい。冷間圧延−焼鈍−冷間圧延を繰り返し
ても良い。焼鈍条件 仕上げ焼鈍温度：1000〜1180℃の範囲で、目的とする材
質に応じて選択する。 目標温度保持時間：０〜1800ｓの範囲で、目的とする材
質に応じて選択する。 また、表面仕上げについては、２Ｄ、２Ｂ、ＢＡおよび
研磨などがある。The molten steel adjusted to the desired steel composition and inclusion composition as described above is cast, hot-rolled, cold-rolled, and annealed in a conventional manner to obtain a product.
Here, suitable hot rolling conditions, cold rolling conditions and annealing conditions are as follows. Hot rolling conditions Slab heating temperature: 1050-1260 ° C, rough rolling temperature: 900-11
80 ° C, total rolling reduction: 80-93%, finishing rolling temperature: 750-1000 ° C, finish rolling exit side thickness: 1.5-7mm,
Winding temperature: 400-850 ° C. Cold Rolling Conditions Cold rolling can be performed by a tandem mill, a cluster mill or a Sendzimir mill. Total rolling reduction 45-95%
The degree is preferred. Cold rolling-annealing-cold rolling may be repeated. Annealing conditions Finish annealing temperature: Select from the range of 1000 to 1180 ° C according to the target material. Target temperature holding time: Select from the range of 0 to 1800 s according to the target material. The surface finish includes 2D, 2B, BA and polishing.
【００４１】[0041]
【実施例】表１に示す成分組成の溶鋼を次のようにして
溶製した。すなわち、脱炭処理後の含クロム溶鋼に対
し、ＶＯＤ炉にて、溶鋼攪拌下に、まず所定量のAlを添
加して予備脱酸を行い、ついでTiを添加してTi脱酸を行
ったのち、成分調整を行い、溶鋼を大気中に移してから
Ca添加を行った。ついで、連続鋳造法にて、厚み：200
mm、幅：1000mmサイズに鋳造した。得られたスラブは手
入れすることなく、次の条件で熱間圧延を行った。 スラブ加熱温度：1170〜1260℃、加熱時間：30〜90分、
粗７パス、粗仕上げ厚み：25mm、粗圧延終了温度：990
〜1120℃、仕上げ（７段ミル）、仕上げ厚：３mm、ＦＤ
Ｔ：800 〜1080℃、ＣＴ：700 〜1030℃。EXAMPLES Molten steel having the composition shown in Table 1 was produced as follows. That is, to the chromium-containing molten steel after the decarburization treatment, in a VOD furnace, while stirring the molten steel, a predetermined amount of Al was first added to perform preliminary deoxidation, and then Ti was added to perform Ti deoxidation. After that, adjust the composition and transfer the molten steel to the atmosphere.
Ca addition was performed. Then, by continuous casting method, thickness: 200
mm, width: cast to 1000mm size. The obtained slab was hot-rolled under the following conditions without care. Slab heating temperature: 1170-1260 ° C, heating time: 30-90 minutes,
Rough 7 passes, rough finish thickness: 25mm, rough rolling end temperature: 990
~ 1120 ℃, Finish (7-step mill), Finish thickness: 3mm, FD
T: 800 to 1080 ° C, CT: 700 to 1030 ° C.
【００４２】得られた熱延コイルを、1090〜1140℃で連
続焼鈍し、酸洗後、冷間圧延により板厚：0.6 mmに仕上
げたのち、1070〜1140℃で連続焼鈍後、酸洗して冷延焼
鈍板とした。かくして得られた冷延焼鈍板について、酸
化物系介在物の組成、連鋳後のノズル閉塞率ならびに冷
延焼鈍板表面のヘゲ欠陥個数および縞状模様発生状況に
ついて調べた結果を、表２に示す。また、同表には、冷
延焼鈍板表面をエメリー＃600 研磨し、塩水噴霧試験
（ＳＳＴ）および塩乾湿複合サイクル腐食試験（ＣＣ
Ｔ）を行った後の発錆個数と発錆面積率について調査し
た結果も併せて示す。表面性状については、冷延板にお
ける表面欠陥発生個数および縞状模様発生の有無で、ま
た耐食性については、塩水噴霧試験および塩乾湿複合サ
イクル腐食試験における発錆個数および発錆面積率で、
それぞれ評価した。The obtained hot-rolled coil was continuously annealed at 1090 to 1140 ° C., pickled, finished to a thickness of 0.6 mm by cold rolling, continuously annealed at 1070 to 1140 ° C., and pickled. To form a cold-rolled annealed plate. Table 2 shows the results of examining the composition of the oxide-based inclusions, the nozzle closing rate after continuous casting, the number of barge defects on the surface of the cold-rolled annealed sheet, and the state of occurrence of the striped pattern of the thus obtained cold-rolled annealed sheet. Shown in The table also shows that the surface of the cold-rolled annealed plate was polished with Emery # 600, subjected to salt spray test (SST) and salt-dry / wet combined cycle corrosion test (CC).
The results of an investigation on the number of rusting and the area ratio of rusting after performing T) are also shown. For the surface properties, the number of surface defects and the presence or absence of striped patterns in the cold-rolled sheet, and for the corrosion resistance, the number of rusts and the area ratio of rust in the salt spray test and the salt dry / wet combined cycle corrosion test,
Each was evaluated.
【００４３】なお、それぞれの特性評価方法は次のとお
りである。 ・冷延焼鈍板中の酸化物系介在物の分析 冷延焼鈍板から試験片を採取し、臭素メタノール系の溶
液中で電解することによって酸化物系介在物を残査とし
て採取したのち、酸に溶解して化学分析を行った。 ・ノズル閉塞率測定法 160 トン連続鋳造後の初期径：60mmのノズルを回収し、
断面を切断して最小径を測定し、（（初期径−鋳込み後
の最小径）／初期径）× 100（％）を閉塞率とした。The respective characteristic evaluation methods are as follows.・ Analysis of oxide-based inclusions in cold-rolled annealed plate A test piece was collected from the cold-rolled annealed plate, and the oxide-based inclusions were collected as a residue by electrolysis in a bromine-methanol-based solution. And subjected to chemical analysis.・ Nozzle clogging rate measurement method The initial diameter after continuous casting of 160 tons: 60 mm nozzle was collected,
The cross section was cut and the minimum diameter was measured, and ((initial diameter−minimum diameter after casting) / initial diameter) × 100 (%) was defined as the closing ratio.
【００４４】・塩水噴霧試験（ＳＳＴ） 冷延焼鈍板表面をエメリー＃600 研磨仕上げ後、脱脂
し、JIS Z 2371に準拠した条件（50℃）で塩水噴霧試験
を４ｈ行い、発錆個数をカウントした。 ・塩乾湿複合サイクル腐食試験（ＣＣＴ） 冷延焼鈍板表面をエメリー＃600 研磨仕上げ後、脱脂
し、35℃で 3.5％NaClを0.5 時間噴霧後、１ｈの乾燥
（60℃）および１ｈ湿潤（40℃、相対湿度：95％以上）
を１サイクルとした複合腐食試験を30サイクル実施し、
発錆面積率を測定した。Salt spray test (SST) After the surface of the cold-rolled annealed plate is polished with Emery # 600, degreased, and subjected to a salt spray test under conditions (50 ° C.) in accordance with JIS Z 2371 for 4 hours, and the number of rusting is counted did.・ Salt dry / wet combined cycle corrosion test (CCT) After the surface of the cold rolled annealed plate is polished with Emery # 600, degreased, sprayed with 3.5% NaCl at 35 ° C for 0.5 hour, dried for 1 hour (60 ° C) and wet for 1 hour (40 hours) ° C, relative humidity: 95% or more)
30 cycles of a composite corrosion test with 1 cycle
The rusting area ratio was measured.
【００４５】[0045]
【表１】 [Table 1]
【００４６】[0046]
【表２】 [Table 2]
【００４７】表２に示したとおり、この発明に従うオー
ステナイト系ステンレス鋼は、その溶製後の連続鋳造時
においてノズル閉塞が全く生じず、また製品板において
も、表面欠陥が全くなく、しかも優れた耐食性を有して
いた。As shown in Table 2, the austenitic stainless steel according to the present invention has no nozzle clogging at the time of continuous casting after its smelting, and has no surface defects in the product sheet and is excellent. It had corrosion resistance.
【００４８】[0048]
【発明の効果】かくして、この発明によれば、酸化物系
介在物に起因した表面欠陥がなく、また耐食性にも優れ
たオーステナイト系ステンレス鋼を安定して得ることが
できる。さらに、この発明のオーステナイト系ステンレ
ス鋼は、その製造過程の連続鋳造時においてノズル閉塞
が生じることもない。As described above, according to the present invention, an austenitic stainless steel having no surface defects due to oxide inclusions and having excellent corrosion resistance can be stably obtained. Further, the austenitic stainless steel of the present invention does not cause nozzle blockage during continuous casting in the production process.
【図１】鋼中のAl量と熱延焼鈍板の表面欠陥個数との関
係を示したグラフである。FIG. 1 is a graph showing the relationship between the amount of Al in steel and the number of surface defects of a hot-rolled annealed sheet.
【図２】酸化物系介在物中の Al2O3濃度とヘゲ状表面欠
陥個数との関係を示したグラフである。FIG. 2 is a graph showing the relationship between the concentration of Al 2 O 3 in oxide-based inclusions and the number of barbed surface defects.
【図３】酸化物系介在物中のTi酸化物濃度とノズル閉塞
率および発錆個数との関係を示したグラフである。FIG. 3 is a graph showing the relationship between the concentration of Ti oxide in oxide-based inclusions, the nozzle closing rate, and the number of rusting.
【図４】酸化物系介在物中のCaＯ濃度とノズル閉塞率お
よび発錆個数との関係を示したグラフである。FIG. 4 is a graph showing the relationship between the CaO concentration in oxide-based inclusions, the nozzle clogging rate, and the number of rusting.
【図５】耐食性に及ぼすＳ量とCa量の影響を、２つの A
l2O3水準で比較して示したグラフである。FIG. 5 shows the effect of S content and Ca content on corrosion resistance in two A
It is a graph shown by comparison at l 2 O 3 level.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 佐藤 進 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 岸本 康夫 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 三木 祐司 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 (72)発明者 反町 健一 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社技術研究所内 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Sato 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Co., Ltd. (72) Yasuo Kishimoto 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Inside the Technical Research Institute of Iron and Steel Corporation (72) Inventor Yuji Miki 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Center of Kawasaki Steel Corporation (72) Kenichi Sorimachi 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Research Institute
Claims (3)
生成物に起因した酸化物系介在物の組成が、Ti酸化物：
20〜90wt％、 Al2O3：50wt％以下およびCaＯ：５〜50wt
％の範囲を満足することを特徴とする表面性状が良好で
耐食性に優れたオーステナイト系ステンレス鋼。[Claim 1] C: 0.15 wt% or less, Si: 1.0 wt% or less, Mn: 2.0 wt% or less, Cr: 15 to 30 wt%, Ni: 5 to 30 wt%, P: 0.05 wt% or less, S: 0.015 wt% or less, N: 0.15 wt% or less, Al: 0.005 wt% or less, O: 0.01 wt% or less, Ti: 0.015 to 0.4 wt%, Ca: 0.0005 to 0.0050 wt%, and the balance is substantially Fe And the composition of the oxide-based inclusions resulting from the deoxidation products in the steel is Ti oxide:
20~90wt%, Al 2 O 3: 50wt% or less, and CaO: 5-50 wt
% Austenitic stainless steel excellent in surface properties and excellent in corrosion resistance.
で耐食性に優れたオーステナイト系ステンレス鋼。2. The austenitic stainless steel according to claim 1, wherein the steel composition further comprises Mo: 0.05 to 6.0 wt%.
さらに Nb：0.01〜0.08wt％、 Ｖ：0.01〜0.1 wt％、 Ｂ：0.
0002〜0.0030wt％ のうちから選んだ１種または２種以上を含有する組成に
なることを特徴とする表面性状が良好で耐食性に優れた
オーステナイト系ステンレス鋼。3. The steel composition according to claim 1, wherein the steel composition is
Further, Nb: 0.01 to 0.08 wt%, V: 0.01 to 0.1 wt%, B: 0.
An austenitic stainless steel having good surface properties and excellent corrosion resistance, characterized by having a composition containing one or more selected from 0002 to 0.0030 wt%.
Priority Applications (1)
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|---|---|---|---|
| JP17188198A JP3772530B2 (en) | 1998-06-18 | 1998-06-18 | Austenitic stainless steel with good surface properties and excellent corrosion resistance |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17188198A JP3772530B2 (en) | 1998-06-18 | 1998-06-18 | Austenitic stainless steel with good surface properties and excellent corrosion resistance |
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| Publication Number | Publication Date |
|---|---|
| JP2000001759A true JP2000001759A (en) | 2000-01-07 |
| JP3772530B2 JP3772530B2 (en) | 2006-05-10 |
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ID=15931535
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|---|---|---|---|
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2818289A1 (en) * | 2000-12-15 | 2002-06-21 | Usinor | Stainless steel for severe working and notably for deep drawing of rolled and heat treated steel sheet with controlled selection of inclusions |
| FR2818290A1 (en) * | 2000-12-15 | 2002-06-21 | Ugine Savoie Imphy | Stainless steel for shaping by severe working and notably by cold striking or drawing into small diameter wires, with a controlled composition for selection of the type and dimensions of its inclusions |
| US6926778B2 (en) | 2002-04-17 | 2005-08-09 | Sumitomo Metal Industries, Ltd. | Austenitic stainless steel excellent in high temperature strength and corrosion resistance, heat resistant pressurized parts, and the manufacturing method thereof |
| KR101022115B1 (en) | 2003-12-09 | 2011-03-17 | 주식회사 포스코 | METHOD FOR PRODUCTING AUSTENITIC STAINLESS STEEL HAVING Ti |
| KR100729123B1 (en) | 2005-12-01 | 2007-06-14 | 주식회사 포스코 | Method of manufacturing for low-carbon austenite stainless steel |
| CN110016618A (en) * | 2019-05-23 | 2019-07-16 | 攀钢集团攀枝花钢铁研究院有限公司 | High silicon content welding steel and preparation method thereof |
| CN110016618B (en) * | 2019-05-23 | 2020-09-25 | 攀钢集团攀枝花钢铁研究院有限公司 | High-silicon-content welding steel and preparation method thereof |
| CN116043134A (en) * | 2023-02-28 | 2023-05-02 | 宝钢德盛不锈钢有限公司 | Austenitic stainless steel with excellent performance and manufacturing method thereof |
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