JP3351837B2 - Al-containing ferritic stainless steel with excellent manufacturability and high-temperature oxidation resistance - Google Patents
Al-containing ferritic stainless steel with excellent manufacturability and high-temperature oxidation resistanceInfo
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- JP3351837B2 JP3351837B2 JP35123892A JP35123892A JP3351837B2 JP 3351837 B2 JP3351837 B2 JP 3351837B2 JP 35123892 A JP35123892 A JP 35123892A JP 35123892 A JP35123892 A JP 35123892A JP 3351837 B2 JP3351837 B2 JP 3351837B2
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- oxidation resistance
- temperature oxidation
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車排ガス装置，暖
房機器等の高温雰囲気に曝される用途に適したＡｌ含有
フェライト系ステンレス鋼に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al-containing ferritic stainless steel suitable for applications exposed to a high-temperature atmosphere such as an automobile exhaust gas device and a heating device.
【０００２】[0002]
【従来の技術】Ａｌ含有フェライト系ステンレス鋼は、
優れた耐高温酸化特性を示し、ストーブのチムニー材等
の暖房器具や電熱用材料として広く使用されてきた。ま
た、最近では、自動車の排ガス浄化装置における触媒コ
ンバータの基材として、従来から使用されてきたセラミ
ックスに代えてＡｌ含有フェライト系ステンレス鋼が使
用されるようになってきている。従来の触媒コンバータ
用基材としてのセラミックスは、熱衝撃に弱く、また熱
容量が大きいために触媒反応温度まで昇温するのに時間
がかかる等の欠陥がある。高Ａｌ含有フェライト系ステ
ンレス鋼等の金属を基材とするメタリックコンバータで
は、これらセラミックスに起因する欠陥を改善すること
ができる。2. Description of the Related Art Al-containing ferritic stainless steels are:
It has excellent resistance to high-temperature oxidation, and has been widely used as a heater and electric heating material such as a stove chimney material. In recent years, Al-containing ferritic stainless steel has been increasingly used as a base material of a catalytic converter in an exhaust gas purifying apparatus for an automobile, instead of a conventionally used ceramic. Conventional ceramics as a base material for a catalytic converter are susceptible to thermal shock and have defects such as a long heat-up time to a catalytic reaction temperature due to a large heat capacity. In a metallic converter based on a metal such as a high Al-containing ferritic stainless steel, defects caused by these ceramics can be improved.
【０００３】メタリックコンバータの基材には、板厚５
０μｍ程度の箔材料が使用される。しかし、箔材料では
異常酸化が発生し易い。また、過酷な酸化条件である排
ガス雰囲気中で使用されるため、非常に優れた耐高温酸
化特性が基材に要求される。この点で、耐高温酸化特性
の改善に有効なＡｌを多量に添加し、且つ希土類元素
（以下、ＲＥＭと略記する）やＹを添加した高Ａｌ含有
フェライト系ステンレス鋼が注目されており、たとえば
２０Ｃｒ−５Ａｌ−ＲＥＭ，Ｙ系ステンレス鋼が使用さ
れている。たとえば、０．０１〜０．５重量％のＹを添
加することにより耐高温酸化特性を高めたＡｌ含有フェ
ライト系ステンレス鋼が特開平４−１２８３４４号公報
で紹介されている。また、特開平４−１２８３４５号公
報では、成分コストを可能な限り低く抑えた条件下で耐
酸化性を高めるため０．０６〜０．１５重量％のＬｎ
（ランタニド族元素）を添加し、且つＬｎとの関係で特
定された量のＰを含有させることにより熱間加工性を改
善したＡｌ含有フェライト系ステンレス鋼が紹介されて
いる。The base material of the metallic converter has a thickness of 5
A foil material of about 0 μm is used. However, abnormal oxidation easily occurs in a foil material. Further, since the substrate is used in an exhaust gas atmosphere under severe oxidizing conditions, the substrate is required to have extremely excellent high-temperature oxidation resistance. In this regard, high Al-containing ferritic stainless steels to which a large amount of Al effective for improving high-temperature oxidation resistance and to which a rare earth element (hereinafter abbreviated as REM) or Y is added have attracted attention. 20Cr-5Al-REM, Y type stainless steel is used. For example, Japanese Patent Application Laid-Open No. 4-128344 discloses an Al-containing ferritic stainless steel in which the high-temperature oxidation resistance is enhanced by adding 0.01 to 0.5% by weight of Y. In Japanese Patent Application Laid-Open No. 4-128345, 0.06 to 0.15% by weight of Ln is used in order to increase oxidation resistance under the condition that component cost is kept as low as possible.
An Al-containing ferritic stainless steel in which hot workability is improved by adding a (lanthanide group element) and adding an amount of P specified in relation to Ln is introduced.
【０００４】[0004]
【発明が解決しようとする課題】メタリックコンバータ
は、セラミックスコンバータに比較して排ガス浄化性能
に優れているものの、素材コストが高く、製造も困難で
ある。すなわち、メタリックコンバータ用として開発さ
れている従来のフェライト系ステンレス鋼は、多量のＣ
ｒ及びＡｌを含むため、靭性が十分でなく、成形加工性
に問題がある。更に、高温酸化特性を改善するためＲＥ
ＭやＹを添加すると、スラブ及びホットコイルの靭性が
著しく低下する。その結果、熱間圧延等の際に割れが発
生し易く、作業能率及び製造歩留りが低く、鋼材コスト
を上昇させる原因になっている。Although a metallic converter is superior in exhaust gas purification performance as compared with a ceramic converter, it has a high material cost and is difficult to manufacture. That is, the conventional ferritic stainless steel developed for the metallic converter has a large amount of carbon.
Since it contains r and Al, the toughness is not sufficient, and there is a problem in moldability. Furthermore, to improve high temperature oxidation characteristics, RE
When M or Y is added, the toughness of the slab and the hot coil is significantly reduced. As a result, cracks are likely to occur during hot rolling or the like, which lowers the work efficiency and the production yield, and causes an increase in steel material costs.
【０００５】加工性は、Ａｌ含有量を低減することによ
って改善される。しかし、単にＡｌ含有量を低下させた
だけでは、耐高温酸化特性が低下し、メタリックコンバ
ータとしての用途に適さなくなる。そのため、加工性を
ある程度犠牲にして、５％程度のＡｌを含有させている
現状である。このように低い加工性は、メタリックコン
バータが普及する上での障害になっている。そこで、靭
性が良好で製造し易く、鋼材コストが低く、従来の２０
Ｃｒ−５Ａｌ−ＲＥＭ，Ｙ系ステンレス鋼と同等以上の
耐高温酸化特性を示す材料が望まれている。本発明は、
このような要求に応えるべく案出されたものであり、Ａ
ｌ，Ｍｎ及びＳｉを低減した条件下でＡｌ含有フェライ
ト系ステンレス鋼に微量のＲＥＭ及び／又はＹを特定量
のＭｏと共に添加することにより、従来のメタリックコ
ンバータ用ステンレス鋼に匹敵する耐高温酸化特性をも
ち、製造性に優れたフェライト系ステンレス鋼を提供す
ることを目的とする。[0005] Workability is improved by reducing the Al content. However, simply reducing the Al content lowers the high-temperature oxidation resistance, and is not suitable for use as a metallic converter. Therefore, at present, about 5% of Al is contained at the expense of workability to some extent. Such low workability is an obstacle to the spread of metallic converters. Therefore, it has good toughness, is easy to manufacture, has a low steel material cost,
Materials exhibiting high-temperature oxidation resistance equal to or higher than that of Cr-5Al-REM, Y stainless steel are desired. The present invention
It was devised to meet such a request, and A
By adding a small amount of REM and / or Y with a specific amount of Mo to an Al-containing ferritic stainless steel under reduced conditions of l, Mn and Si, high-temperature oxidation resistance comparable to conventional stainless steel for metallic converters An object of the present invention is to provide a ferritic stainless steel having excellent manufacturability.
【０００６】[0006]
【課題を解決するための手段】本発明のＡｌ含有フェラ
イト系ステンレス鋼は、その目的を達成するため、Ｃ：
０．０３重量％以下，Ｓｉ：０．２重量％以下，Ｍｎ：
０．３重量％以下，Ｐ：０．０４重量％以下，Ｓ：０．
００３重量％以下，Ｃｒ：１５〜２５重量％，Ｎ：０．
０３重量％以下，Ａｌ：１重量％以上で４．５重量％未
満，Ｍｏ：０．５〜２重量％，ＲＥＭ及びＹの１種又は
２種以上：合計で０．０１〜０．１５重量％を含み、残
部が実質的にＦｅであることを特徴とする。このＡｌ含
有フェライト系ステンレス鋼は、更にＶ及び／又はＴｉ
を合計で０．０１〜０．５重量％を含むこともできる。SUMMARY OF THE INVENTION The Al-containing ferritic stainless steel according to the present invention has a C:
0.03% by weight or less, Si: 0.2% by weight or less, Mn:
0.3% by weight or less, P: 0.04% by weight or less, S: 0.
003% by weight or less, Cr: 15 to 25% by weight, N: 0.
03 wt% or less, Al: 1 wt% or more and less than 4.5 wt%, Mo: 0.5 to 2 wt%, one or more of REM and Y: 0.01 to 0.15 wt% in total %, And the balance is substantially Fe. This Al-containing ferritic stainless steel further includes V and / or Ti
May be contained in a total amount of 0.01 to 0.5% by weight.
【０００７】[0007]
【作 用】メタリックコンバータ用として使用されてい
る従来の高Ａｌ含有フェライト系ステンレス鋼が低い靭
性を示すことは、多量のＣｒ及びＡｌを含有しているこ
とに原因がある。Ａｌ含有量の低下により靭性の改善が
図られるものの、単にＡｌ含有量を低くしただけでは耐
高温酸化特性が劣化する。本発明者等は、良好な靭性が
確保されるようにＡｌ含有量を４．５重量％未満の低下
させたフェライト系ステンレス鋼について、各種合金元
素が与える影響を調査・研究した。その結果、Ｍｎ及び
Ｓｉを低減した条件下でＭｏを含有させるとき、４．５
重量％未満の低いＡｌ含有量であっても、優れた耐高温
酸化特性が得られることを見い出した。[Work] The fact that a conventional high Al-containing ferritic stainless steel used for a metallic converter shows low toughness is due to the fact that it contains a large amount of Cr and Al. Although the toughness is improved by lowering the Al content, simply reducing the Al content deteriorates the high-temperature oxidation resistance. The present inventors investigated and studied the effects of various alloying elements on a ferritic stainless steel in which the Al content was reduced to less than 4.5% by weight so as to ensure good toughness. As a result, when Mo is contained under the condition where Mn and Si are reduced, 4.5 is contained.
It has been found that excellent high temperature oxidation resistance can be obtained even with a low Al content of less than 10% by weight.
【０００８】Ａｌ含有フェライト系ステンレス鋼の耐高
温酸化特性は改善にＭｏは有効であるが、このＭｏの効
果は、低Ｍｎ化及び低Ｓｉ化によって著しく大きくな
る。その詳細な理由は不明であるが、４．５重量％以上
の高Ａｌ含有フェライト系ステンレス鋼に匹敵する耐高
温酸化特性を付与することができる。しかも、Ａｌ含有
量が少ないことから、良好な靭性や加工性も確保され
る。本発明は、この高温雰囲気下における異常酸化の発
生機構に及ぼす各種合金元素の影響を調査・研究した結
果、完成されたものである。すなわち、Ｍｎ含有量及び
Ｓｉ含有量を低下した条件下で微量のＲＥＭ及び／又は
ＹとＭｏとを添加するとき、非常に優れた耐高温酸化特
性が得られ、１１５０℃の高温に長時間保持した場合で
も異常酸化を起こすことがなくなることを見い出した。
低Ｍｎ化及び低Ｓｉ化は、その詳細な理由は不明である
が、Ｍｏ，ＲＥＭ，Ｙ等の作用を有効に発揮させること
に寄与しているものと推察される。そのため、多量のＭ
ｏ，ＲＥＭ，Ｙ等を添加する必要がなく、良好な加工性
や強度も確保される。[0008] Mo is effective in improving the high-temperature oxidation resistance of Al-containing ferritic stainless steel, but the effect of Mo is significantly increased by reducing Mn and Si. Although the detailed reason is unknown, it is possible to impart high-temperature oxidation resistance comparable to that of a high-Al-containing ferritic stainless steel of 4.5% by weight or more. Moreover, since the Al content is small, good toughness and workability are also ensured. The present invention has been completed as a result of investigating and studying the effects of various alloying elements on the mechanism of occurrence of abnormal oxidation in this high-temperature atmosphere. That is, when a very small amount of REM and / or Y and Mo are added under the condition that the Mn content and the Si content are reduced, very excellent high-temperature oxidation resistance is obtained, and the high-temperature oxidation at 1150 ° C. is maintained for a long time. It is found that abnormal oxidation does not occur even if it is performed.
Although the detailed reasons for the low Mn and low Si are unknown, it is presumed that they contribute to effectively exhibiting the effects of Mo, REM, Y, and the like. Therefore, a large amount of M
There is no need to add o, REM, Y, etc., and good workability and strength are ensured.
【０００９】以下、本発明のＡｌ含有フェライト系ステ
ンレス鋼に含まれる合金元素及びその含有量を説明す
る。 Ｃ： Ｃ含有量の増加に伴って、異常酸化が発生し易く
なる。また、多量のＣ含有は、スラブ及びホットコイル
の靭性を劣化させ、熱間加工によって板材に加工するこ
とが困難になる。したがって、本発明においては、Ｃ含
有量の上限を０．０３重量％に規定した。 Ｓｉ： 一般的にＳｉはステンレス鋼の耐高温酸化性を
改善する上で有効であるとされ、積極的な合金元素とし
て耐高温酸化用ステンレス鋼に添加されている。しか
し、Ａｌ含有フェライト系ステンレス鋼においては、Ｓ
ｉを極力低減させることによって耐高温酸化性の改善が
図られ、異常酸化が発生しにくくなる。このようなＳｉ
低減による効果は、本発明者等によって見出された現象
であり、Ｓｉ含有量０．２重量％以下で顕著に現れる。Hereinafter, alloying elements contained in the Al-containing ferritic stainless steel of the present invention and the contents thereof will be described. C: As the C content increases, abnormal oxidation tends to occur. Further, a large amount of C content deteriorates the toughness of the slab and the hot coil, and it becomes difficult to process the sheet material by hot working. Therefore, in the present invention, the upper limit of the C content is specified as 0.03% by weight. Si: Generally, Si is considered to be effective in improving the high-temperature oxidation resistance of stainless steel, and is added to the high-temperature oxidation-resistant stainless steel as an active alloying element. However, in an Al-containing ferritic stainless steel, S
By reducing i as much as possible, high-temperature oxidation resistance is improved, and abnormal oxidation hardly occurs. Such Si
The effect of the reduction is a phenomenon found by the present inventors, and appears remarkably when the Si content is 0.2% by weight or less.
【００１０】Ｍｎ： 熱間加工性を向上させる上で有効
な合金元素であるが、高Ａｌフェライト系ステンレス鋼
においては耐高温酸化特性に悪影響を及ぼし、短時間で
異常酸化が発生する。Ｍｎ含有量が耐高温酸化特性に与
える影響は、本発明者等が見い出した現象であり、本成
分系鋼の表層に形成されるＡｌ2 Ｏ3 皮膜中にＭｎが混
入し、耐高温酸化特性に悪影響を及ぼすＣｒ系，Ｍｎ系
の酸化物を生成させ、異常酸化の発生を助長する。異常
酸化を抑制し耐高温酸化特性を向上させる上から、Ｍｎ
含有量は可能な限り少なくすることが好ましい。また、
Ｍｎ含有量の低下に伴って、靭性も向上する。しかし、
製鋼用原料であるスクラップから混入することから、Ｍ
ｎ含有量を極端に低下することは、製造コストの上昇を
招く。そこで、本発明においては、Ｍｎ含有量の上限を
０．３重量％，好ましくは０．２重量％に規定した。Mn: An alloy element effective for improving hot workability, but has an adverse effect on high-temperature oxidation resistance in high Al ferritic stainless steel, and abnormal oxidation occurs in a short time. The effect of the Mn content on the high-temperature oxidation resistance is a phenomenon discovered by the present inventors, and Mn is mixed in the Al 2 O 3 film formed on the surface layer of the component steel, and the high-temperature oxidation resistance is high. Cr- and Mn-based oxides, which have an adverse effect on water, are generated to promote the occurrence of abnormal oxidation. In order to suppress abnormal oxidation and improve high-temperature oxidation resistance, Mn
The content is preferably as low as possible. Also,
As the Mn content decreases, the toughness also increases. But,
Since it is mixed from scrap, which is a raw material for steelmaking, M
Extremely lowering the n content causes an increase in manufacturing cost. Therefore, in the present invention, the upper limit of the Mn content is set to 0.3% by weight, preferably 0.2% by weight.
【００１１】Ｐ： 耐高温酸化特性に悪影響を及ぼす元
素であり、低い方が好ましい。また、Ｐ含有量が高い
と、熱延板の靭性も低下する。そこで、本発明において
は、Ｐ含有量を０．０４重量％以下に規定した。 Ｓ： ＲＥＭ及びＹと結合して硫化物系介在物となり、
鋼の表面性状を悪化させる。また、硫化物の生成によ
り、耐高温酸化特性に寄与するＲＥＭ及びＹを消費す
る。そのため、多量のＲＥＭ，Ｙ等を添加することが必
要となり、鋼の靭性を劣化させる。Ｓによる弊害は、含
有量が０．００３重量％を超えると顕著に現れる。そこ
で、本発明においては、Ｓ含有量の上限を０．００３重
量％，好ましくは０．００２重量％に規定した。P: an element that has an adverse effect on the high-temperature oxidation resistance, and the lower the element, the better. Further, when the P content is high, the toughness of the hot-rolled sheet also decreases. Therefore, in the present invention, the P content is specified to be 0.04% by weight or less. S: Combined with REM and Y to form sulfide inclusions,
Deteriorates the surface properties of steel. In addition, REM and Y that contribute to high-temperature oxidation resistance are consumed due to the formation of sulfide. Therefore, it is necessary to add a large amount of REM, Y, and the like, thereby deteriorating the toughness of the steel. The adverse effects of S become remarkable when the content exceeds 0.003% by weight. Therefore, in the present invention, the upper limit of the S content is set to 0.003% by weight, preferably 0.002% by weight.
【００１２】Ｃｒ： 鋼の耐高温酸化特性を改善するた
めに必要な基本的な合金元素である。１５重量％以上の
Ｃｒを含有させることにより、堅牢な酸化皮膜が形成さ
れ、鋼の異常酸化が抑制される。しかし、２５重量％を
超える多量のＣｒを含有すると、スラブ及びホットコイ
ルの靭性が低下し、製造性が悪くなる。したがって、本
発明においては、Ｃｒ含有量を１５〜２５重量％の範囲
に設定した。 Ｎ： 鋼中のＡｌと結合し、異常酸化の起点となるＡｌ
Ｎを生成する。また、ステンレス鋼の靭性を低下し、製
造性を悪化させる。そこで、本発明においては、Ｎ含有
量の上限を０．０３重量％に規定した。Cr is a basic alloying element necessary for improving the high-temperature oxidation resistance of steel. By containing 15% by weight or more of Cr, a robust oxide film is formed, and abnormal oxidation of steel is suppressed. However, when a large amount of Cr exceeding 25% by weight is contained, the toughness of the slab and the hot coil decreases, and the manufacturability deteriorates. Therefore, in the present invention, the Cr content is set in the range of 15 to 25% by weight. N: Al that combines with Al in steel and is a starting point for abnormal oxidation
Generate N. Also, it lowers the toughness of stainless steel and deteriorates manufacturability. Therefore, in the present invention, the upper limit of the N content is set to 0.03% by weight.
【００１３】Ａｌ： Ｃｒと同様に耐高温酸化特性を維
持するために必要な合金元素であり、表層にＡｌ2 Ｏ3
を形成することによって優れた耐高温酸化特性を付与す
る。特に板厚が１００μｍ以下の箔材料では、異常酸化
の抑制に有効なＡｌ2 Ｏ3 層を十分に発達させるため、
１重量％以上のＡｌを含有させる。しかし、４．５重量
％以上に多量のＡｌを含有すると、スラブ及びホットコ
イルの靭性が劣化し、製造歩留りの低下、ひいては鋼材
コストの上昇を招く。そこで、本発明においては、靭性
及び加工性を考慮して、Ａｌ含有量を１重量％以上で
４．５重量％未満の範囲に設定した。Al: Like Cr, it is an alloy element necessary for maintaining high-temperature oxidation resistance. Al 2 O 3
By forming the compound, excellent high-temperature oxidation resistance is imparted. Particularly in a foil material having a thickness of 100 μm or less, an Al 2 O 3 layer effective for suppressing abnormal oxidation is sufficiently developed.
Al is contained in an amount of 1% by weight or more. However, when a large amount of Al is contained in an amount of 4.5% by weight or more, the toughness of the slab and the hot coil is deteriorated, and the production yield is reduced, and the cost of steel is increased. Therefore, in the present invention, in consideration of toughness and workability, the Al content is set in a range of 1% by weight or more and less than 4.5% by weight.
【００１４】Ｍｏ： 本発明のステンレス鋼において重
要な役割を果す合金元素である。従来、Ｍｏは、揮発性
の高い酸化物を形成し易いことから、鋼の耐高温酸化特
性を劣化するとされている。しかし、低Ｓｉ化及び低Ｍ
ｎ化した本発明のステンレス鋼においては、Ｍｏの添加
によって耐高温酸化特性が著しく改善され、高温強度も
優れたものとなる。このようなＭｏの効果は、０．５重
量％以上の含有量で顕著に現れる。しかし、多量にＭｏ
を添加させると、鋼の靭性が劣化し、製造性が悪くな
る。そこで、本発明においては、Ｍｏ含有量を０．５〜
２重量％の範囲に設定した。Mo: An alloy element that plays an important role in the stainless steel of the present invention. Conventionally, Mo is considered to deteriorate the high-temperature oxidation resistance of steel because it easily forms an oxide having high volatility. However, low Si and low M
In the n-type stainless steel of the present invention, the high-temperature oxidation resistance is significantly improved by the addition of Mo, and the high-temperature strength is also excellent. Such an effect of Mo is remarkably exhibited at a content of 0.5% by weight or more. However, a lot of Mo
, The toughness of the steel deteriorates and the manufacturability deteriorates. Therefore, in the present invention, the Mo content is 0.5 to
It was set in the range of 2% by weight.
【００１５】ＲＥＭ及びＹ： 高Ａｌフェライト系ステ
ンレス鋼の耐高温酸化特性を改善するために重要な合金
元素である。Ｌａ，Ｃｅ等のＲＥＭやＹを添加すると、
鋼材表面に形成される酸化皮膜が緻密化し、安定性に優
れたものとなる。その結果、箔材料で発生し易い異常酸
化が抑制される。また、下地鋼に対する酸化皮膜の密着
性も向上する。REM and Y are important alloying elements for improving the high temperature oxidation resistance of high Al ferritic stainless steel. When REM or Y such as La and Ce is added,
The oxide film formed on the surface of the steel material is densified and has excellent stability. As a result, abnormal oxidation which is easily generated in the foil material is suppressed. Further, the adhesion of the oxide film to the base steel is also improved.
【００１６】ＲＥＭ及びＹが耐酸化性の向上及び異常酸
化の抑制に与える効果は、０．０１重量％以上の含有で
顕著になる。しかし、０．１５重量％を超える多量のＲ
ＥＭ及びＹを含有させると、熱間加工性及び靭性が悪化
し、製造が困難になる。また、多量のＲＥＭ及びＹ含有
は、異常酸化の起点となる非金属介在物の析出を助長さ
せ、却って耐高温酸化特性を劣化させる。したがって、
本発明においては、ＲＥＭ及びＹの含有量を合計で０．
０１〜０．１５重量％の範囲に設定した。The effects of REM and Y on improving oxidation resistance and suppressing abnormal oxidation become remarkable when the content is 0.01% by weight or more. However, large amounts of R exceeding 0.15% by weight
When EM and Y are contained, hot workability and toughness deteriorate, and production becomes difficult. Further, a large amount of REM and Y contained promotes precipitation of non-metallic inclusions which are a starting point of abnormal oxidation, and rather deteriorates high-temperature oxidation resistance. Therefore,
In the present invention, the contents of REM and Y are set to 0.1 in total.
It was set in the range of 01 to 0.15% by weight.
【００１７】Ｖ及びＴｉ： 本発明のＡｌ含有フェライ
ト系ステンレス鋼に必要に応じて添加される合金元素で
あり、鋼中のＣ又はＮと結合することにより鋼の靭性を
著しく改善する作用を呈する。メタリックコンバータ等
の高温用途に使用されるステンレス鋼は、冷熱サイクル
を受けるため、酸化皮膜が剥離し易い環境に曝される。
下地鋼に対する酸化皮膜の密着性は、前述したＲＥＭ及
びＹに加え、Ｖ又はＴｉによっても改善することができ
る。そこで、靭性の低下や鋼材コストの上昇につながり
易いＲＥＭ及びＹの添加量を低く抑え、その分をＶ又は
Ｔｉで補償することができる。これにより、非常に優れ
た密着性を酸化皮膜に与え、異常酸化を抑制することが
可能になる。このような効果を得るためには、合計で
０．０１重量％以上のＶ又はＴｉを含有させることが必
要である。しかし、０．５重量％を超えて多量のＶ又は
Ｔｉが含まれると、鋼が硬質になり、加工性が劣化す
る。そこで、Ｖ又はＴｉを含有させる場合には、その範
囲を０．０１〜０．５重量％に設定する。V and Ti: Alloying elements that are added as necessary to the Al-containing ferritic stainless steel of the present invention, and exhibit an effect of significantly improving the toughness of the steel when combined with C or N in the steel. . Stainless steel used for high-temperature applications such as a metallic converter is exposed to an environment in which an oxide film is easily peeled because it undergoes a thermal cycle.
The adhesion of the oxide film to the base steel can be improved by V or Ti in addition to REM and Y described above. Therefore, the addition amount of REM and Y, which tend to lead to a decrease in toughness and an increase in steel material cost, can be suppressed low, and V or Ti can compensate for that. Thereby, it is possible to give extremely excellent adhesion to the oxide film and suppress abnormal oxidation. In order to obtain such an effect, it is necessary to contain V or Ti in a total amount of 0.01% by weight or more. However, if a large amount of V or Ti is contained in excess of 0.5% by weight, the steel becomes hard and workability deteriorates. Therefore, when V or Ti is contained, the range is set to 0.01 to 0.5% by weight.
【００１８】[0018]
実施例１：表１に示す各種ステンレス鋼を真空溶解し、
鍛造，切削，熱延を行った後、焼鈍及び冷間圧延を繰り
返し、板厚５０μｍの箔材料を製造した。得られた箔材
料を１１５０℃の酸化試験に供し、異常酸化が発生する
までの時間を調査した。異常酸化の発生は、各供試材を
適宜加熱炉から取り出し、通常検出される薄く且つ均一
な酸化皮膜の他に隆起状酸化物を目視観察することによ
り判定した。そして、この隆起状酸化物が観察されるま
での通算酸化時間を、異常酸化発生時間として表１に示
した。表１において、試験記号Ａは、メタリックコンバ
ータ用として従来から使用されている鋼であり、１１５
０℃の加熱試験で１７０時間まで異常酸化を起こさな
い。試験記号Ｂは、Ａ鋼に比較してＡｌ含有量を３重量
％まで下げた鋼であり、８５時間で異常酸化が発生して
いる。また、Ａｌ含有量及びＣｒ含有量をそれぞれ３重
量％及び１８重量％まで下げた鋼Ｃでは、８０時間で異
常酸化が発生した。このことから、靭性の改善を狙って
単にＣｒ含有量及びＡｌ含有量を下げただけでは、メタ
リックコンバータ用として要求される高温酸化特性をも
たなくなることが判る。Example 1: Various stainless steels shown in Table 1 were melted in vacuum,
After forging, cutting and hot rolling, annealing and cold rolling were repeated to produce a 50 μm-thick foil material. The obtained foil material was subjected to an oxidation test at 1150 ° C., and the time until abnormal oxidation occurred was examined. The occurrence of abnormal oxidation was determined by appropriately taking out each test material from the heating furnace and visually observing a raised oxide in addition to a thin and uniform oxide film which is usually detected. Table 1 shows the total oxidation time until the protruding oxide was observed as the abnormal oxidation occurrence time. In Table 1, the test symbol A is steel conventionally used for metallic converters,
Does not cause abnormal oxidation up to 170 hours in a heating test at 0 ° C. Test symbol B is a steel in which the Al content has been reduced to 3% by weight as compared with steel A, and abnormal oxidation has occurred in 85 hours. In steel C in which the Al content and the Cr content were reduced to 3% by weight and 18% by weight, respectively, abnormal oxidation occurred in 80 hours. From this, it is understood that simply lowering the Cr content and the Al content for the purpose of improving toughness does not have the high-temperature oxidation characteristics required for a metallic converter.
【表１】 [Table 1]
【００１９】良好な靭性が確保されるＡｌ含有量３〜４
重量％の範囲で、他の合金元素が耐高温酸化特性に与え
る影響を調査した。なお、耐高温酸化特性の改善に有効
であることが知られているＲＥＭ，Ｙ等は、原料価格が
極めて高く、しかも添加量が多くなるに従って靭性を著
しく低下させる。したがって、本実施例においては、Ｒ
ＥＭ及びＹの添加量０．０６重量％を限度として検討を
進めた。この検討の過程で、Ｍｏ添加により耐高温酸化
特性が改善されることを見い出した。表１の試験記号Ｄ
〜Ｇは、耐高温酸化特性に与えるＭｏ含有量の影響を調
べた鋼である。Ｄ〜Ｇ鋼の耐高温酸化特性に関する試験
結果をＭｏ含有量との関係で整理したところ、図１に示
すようにＭｏ含有量の増加に伴って耐高温酸化特性が改
善され、異常酸化が発生するまでの時間が長くなってい
る。しかし、Ｄ〜Ｇ鋼を熱間圧延したままのホットコイ
ルは、Ｍｏ含有量の増加に伴って靭性が低下する傾向が
みられる。Al content 3-4 ensuring good toughness
The effect of other alloying elements on high-temperature oxidation resistance was investigated in the range of weight percent. REM, Y, and the like, which are known to be effective in improving high-temperature oxidation resistance, have extremely high raw material prices, and furthermore, the toughness is remarkably reduced as the added amount increases. Therefore, in this embodiment, R
The study was conducted with the addition amount of EM and Y being limited to 0.06% by weight. In the course of this study, it was found that the high-temperature oxidation resistance was improved by adding Mo. Test symbol D in Table 1
-G are steels for which the effect of Mo content on high temperature oxidation resistance has been investigated. When the test results on the high-temperature oxidation resistance of the D to G steels were arranged in relation to the Mo content, as shown in FIG. 1, the high-temperature oxidation resistance was improved as the Mo content increased, and abnormal oxidation occurred. The time to do it is longer. However, in a hot coil in which the DG steel is hot-rolled, the toughness tends to decrease as the Mo content increases.
【００２０】試験記号Ｈ及びＩとして示すように、Ｍｎ
含有量を低下した条件下でＭｏを添加したとき、靭性の
回復がみられた。また、Ｍｎ含有量の低下は、耐高温酸
化特性の改善にも有効であった。Ｈ鋼及びＩ鋼は、Ｍｎ
以外の成分含有量がＧ鋼とほぼ同じであるにも拘らず、
Ｇ鋼に比較して靭性が向上しており、異常酸化を発生さ
せるまでの時間も長くなっている。しかし、量産ライン
による製造を考慮するとき、スクラップから混入するＭ
ｎの含有量を低くコントロールすることは困難であるこ
とから、他の合金元素が与える影響を調査した。その結
果、Ｍｎと共にＳｉを低減させるとき、靭性及び耐高温
酸化特性が更に改善されることが判った。As shown by test symbols H and I, Mn
When Mo was added under the condition where the content was reduced, recovery of toughness was observed. Also, the reduction in the Mn content was effective in improving the high-temperature oxidation resistance. H steel and I steel are Mn
Despite that the content of other components is almost the same as G steel,
The toughness is improved as compared with the G steel, and the time until abnormal oxidation is generated is also longer. However, when considering production on a mass production line, M
Since it is difficult to control the content of n low, the effects of other alloying elements were investigated. As a result, it was found that when Si was reduced together with Mn, toughness and high-temperature oxidation resistance were further improved.
【００２１】Ｓｉは、従来からステンレス鋼の耐高温酸
化特性の改善に有効な元素とされ、積極的に添加されて
いる。しかし、本発明者等の検討によるとき、Ｍｏを添
加したＡｌ含有フェライト系ステンレス鋼においては、
Ｓｉ含有量の増加に伴って却って耐高温酸化特性が劣化
し、異常酸化が発生し易くなることが判明した。たとえ
ば、Ｓｉ含有量を低下させたＭｏ添加Ａｌ含有フェライ
ト系ステンレス鋼（試験記号Ｊ〜Ｌ）にみられるよう
に、Ｓｉ含有量が低くなると共に優れた耐高温酸化特性
が示されている。また、Ｓｉ含有量が少ないＪ〜Ｌ鋼の
靭性は、Ｇ鋼に比較し著しく大きな値を示している。Conventionally, Si has been regarded as an effective element for improving the high-temperature oxidation resistance of stainless steel, and has been positively added. However, according to the study of the present inventors, in the Al-containing ferritic stainless steel to which Mo is added,
It has been found that the high-temperature oxidation resistance is rather deteriorated with an increase in the Si content, and abnormal oxidation is likely to occur. For example, as shown in the Mo-added Al-containing ferritic stainless steel in which the Si content is reduced (test symbols J to L), the Si content is reduced and excellent high-temperature oxidation resistance is exhibited. Further, the toughness of the J to L steels having a small Si content shows a remarkably large value as compared with the G steel.
【００２２】なお、Ｓｉは脱酸効果を得るために添加さ
れることがあるが、Ａｌ含有フェライト系ステンレス鋼
では、脱酸効果の大きなＡｌを多量に添加していること
から、特にＳｉ脱酸の必要はない。したがって、量産ラ
インで製造するに際し、Ｓｉ含有量を極力低くすること
は可能である。以上のことから、Ｍｎ含有量及びＳｉ含
有量を低減した条件下でＭｏを添加するとき、Ａｌ含有
量が低いものでも従来の高Ａｌ含有フェライト系ステン
レス鋼と同様以上の耐高温酸化特性を示すことが判る。
しかも、低Ｍｎ及び低Ｓｉによって靭性の改善が図ら
れ、割れ等の欠陥を発生させることなく熱間圧延できる
材料が得られた。Incidentally, Si is sometimes added in order to obtain a deoxidizing effect. However, in an Al-containing ferritic stainless steel, since a large amount of Al having a large deoxidizing effect is added, Si is particularly deoxidized. There is no need for Therefore, when manufacturing in a mass production line, it is possible to reduce the Si content as much as possible. From the above, when Mo is added under the condition that the Mn content and the Si content are reduced, even when the Al content is low, the same high-temperature oxidation resistance as the conventional high Al-containing ferritic stainless steel is exhibited. You can see that.
In addition, toughness was improved by low Mn and low Si, and a material that could be hot-rolled without generating defects such as cracks was obtained.
【００２３】実施例２：表２に示した各種鋼を使用し、
実施例１と同様に板厚５０μｍの箔材料を製造した。各
供試材を１１５０℃の酸化試験に供し、異常酸化が発生
した時間を測定した。試験結果を、表２に併せ示す。Example 2: Using various steels shown in Table 2,
A 50 μm-thick foil material was manufactured in the same manner as in Example 1. Each test material was subjected to an oxidation test at 1150 ° C., and the time when abnormal oxidation occurred was measured. The test results are shown in Table 2.
【表２】 [Table 2]
【００２４】本発明に従った試験番号１〜７の供試材
は、何れも異常酸化発生時間が２００時間を超えてお
り、メタリックコンバータ用に従来から使用されている
比較鋼８よりも優れた耐高温酸化特性を示していた。ま
た、試験番号１〜７の供試材は、熱延したままのホット
コイルとして、１９Ｊ／ｃｍ2 以上の優れた衝撃靭性を
示した。そのため、製造性に優れ、作業能率が良く、且
つ歩留りの低下が少ないことから、製造コストを低くす
ることができた。これに対し、比較鋼９，１０及び１２
は、Ａｌ含有量が低いことから衝撃靭性が良好であるも
のの、７５時間以内に異常酸化が発生しており、耐高温
酸化特性に劣っていた。また、Ａｌ含有量及びＭｏ含有
量を共に３重量％以上とした比較鋼１１は、耐高温酸化
性が良好であるものの、衝撃靭性が極めて低く、製造が
困難であった。更に、比較鋼１３は、Ａｌ，Ｓｉ及びＭ
ｏを多量に含むことから、靭性が非常に低く、熱間圧延
できないものであった。The test materials of Test Nos. 1 to 7 according to the present invention all have abnormal oxidation occurrence times exceeding 200 hours, and are superior to the comparative steel 8 conventionally used for metallic converters. It showed high temperature oxidation resistance. Further, the test materials of Test Nos. 1 to 7 exhibited excellent impact toughness of 19 J / cm 2 or more as a hot coil as hot rolled. Therefore, the manufacturing cost was reduced because of excellent manufacturability, good work efficiency, and little decrease in yield. In contrast, comparative steels 9, 10 and 12
Although the impact toughness was good due to the low Al content, abnormal oxidation occurred within 75 hours, and the high temperature oxidation resistance was poor. Further, Comparative Steel 11, in which both the Al content and the Mo content were 3% by weight or more, had good high-temperature oxidation resistance, but had extremely low impact toughness and was difficult to manufacture. Further, the comparative steel 13 is made of Al, Si and M
Since it contained a large amount of o, the toughness was extremely low and hot rolling could not be performed.
【００２５】[0025]
【発明の効果】以上に説明したように、本発明のＡｌ含
有フェライト系ステンレス鋼においては、低Ｍｎ及び低
Ｓｉの条件下で特定量のＭｏを添加することにより、Ａ
ｌ含有量が比較的低いものであっても、優れた耐高温酸
化特性を付与することができる。しかも、Ｍｎ及びＳｉ
の低減は、Ａｌ含有量の低下と相俟つてフェライト系ス
テンレス鋼の靭性及び製造性，加工性を改善する。した
がって、安価なコストでメタリックコンバータ等の高温
用途に適した材料が得られる。As described above, in the Al-containing ferritic stainless steel of the present invention, the addition of a specific amount of Mo under the conditions of low Mn and low Si allows the A
Even if the l content is relatively low, excellent high-temperature oxidation resistance can be imparted. Moreover, Mn and Si
The reduction of Al, together with the reduction of Al content, improves the toughness, manufacturability and workability of ferritic stainless steel. Therefore, a material suitable for high-temperature applications such as a metallic converter can be obtained at low cost.
【図１】 板厚５０μｍのＡｌ含有フェライト系ステン
レス鋼の１１５０℃における異常酸化発生に及ぼすＭｏ
含有量の影響FIG. 1 shows the effect of Mo on abnormal oxidation of Al-containing ferritic stainless steel having a thickness of 50 μm at 1150 ° C.
Effect of content
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平４−354850（ＪＰ，Ａ) 特開 平４−147945（ＪＰ，Ａ) 特開 平３−53025（ＪＰ，Ａ) 特開 昭60−228616（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C22C 38/00 - 38/60 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-354850 (JP, A) JP-A-4-147945 (JP, A) JP-A-3-53025 (JP, A) JP-A-60-1985 228616 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C22C 38/00-38/60
Claims (2)
重量％以下，Ｍｎ：０．３重量％以下，Ｐ：０．０４重
量％以下，Ｓ：０．００３重量％以下，Ｃｒ：１５〜２
５重量％，Ｎ：０．０３重量％以下，Ａｌ：１重量％以
上で４．５重量％未満，Ｍｏ：０．５〜２重量％，希土
類元素及びＹの１種又は２種以上：合計で０．０１〜
０．１５重量％を含み、残部が実質的にＦｅであること
を特徴とする製造性及び耐高温酸化性に優れたＡｌ含有
フェライト系ステンレス鋼。1. C: 0.03% by weight or less, Si: 0.2
Wt% or less, Mn: 0.3 wt% or less, P: 0.04 wt% or less, S: 0.003 wt% or less, Cr: 15 to 2
5% by weight, N: 0.03% by weight or less, Al: 1% by weight or more and less than 4.5% by weight, Mo: 0.5 to 2% by weight, one or more of rare earth elements and Y: total At 0.01 ~
An Al-containing ferritic stainless steel containing 0.15% by weight, with the balance being substantially Fe, and having excellent productivity and high-temperature oxidation resistance.
重量％以下，Ｍｎ：０．３重量％以下，Ｐ：０．０４重
量％以下，Ｓ：０．００３重量％以下，Ｃｒ：１５〜２
５重量％，Ｎ：０．０３重量％以下，Ａｌ：１重量％以
上で４．５重量％未満，Ｍｏ：０．５〜２重量％，Ｖ及
び／又はＴｉ：合計で０．０１〜０．５重量％，希土類
元素及びＹの１種又は２種以上：合計で０．０１〜０．
１５重量％を含み、残部が実質的にＦｅであることを特
徴とする製造性及び耐高温酸化性に優れたＡｌ含有フェ
ライト系ステンレス鋼。2. C: 0.03% by weight or less, Si: 0.2
Wt% or less, Mn: 0.3 wt% or less, P: 0.04 wt% or less, S: 0.003 wt% or less, Cr: 15 to 2
5 wt%, N: 0.03 wt% or less, Al: 1 wt% or more and less than 4.5 wt%, Mo: 0.5 to 2 wt%, V and / or Ti: 0.01 to 0 in total 0.5% by weight, one or more of rare earth elements and Y: 0.01 to 0.2 in total.
An Al-containing ferritic stainless steel excellent in productivity and high-temperature oxidation resistance, comprising 15% by weight and the balance being substantially Fe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35123892A JP3351837B2 (en) | 1992-12-07 | 1992-12-07 | Al-containing ferritic stainless steel with excellent manufacturability and high-temperature oxidation resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35123892A JP3351837B2 (en) | 1992-12-07 | 1992-12-07 | Al-containing ferritic stainless steel with excellent manufacturability and high-temperature oxidation resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06172933A JPH06172933A (en) | 1994-06-21 |
| JP3351837B2 true JP3351837B2 (en) | 2002-12-03 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP35123892A Expired - Fee Related JP3351837B2 (en) | 1992-12-07 | 1992-12-07 | Al-containing ferritic stainless steel with excellent manufacturability and high-temperature oxidation resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3351837B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8518234B2 (en) * | 2003-09-03 | 2013-08-27 | Ati Properties, Inc. | Oxidation resistant ferritic stainless steels |
| SE528027C2 (en) * | 2004-04-16 | 2006-08-08 | Sandvik Intellectual Property | Use of a ferritic steel in catalysts for diesel engines |
| CN105304258A (en) * | 2015-12-03 | 2016-02-03 | 钢铁研究总院 | Corrosion-resisting magnetically soft alloy |
-
1992
- 1992-12-07 JP JP35123892A patent/JP3351837B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06172933A (en) | 1994-06-21 |
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