JP3219099B2 - Ferrite heat-resistant stainless steel with excellent heat resistance, low temperature toughness and weldability - Google Patents
Ferrite heat-resistant stainless steel with excellent heat resistance, low temperature toughness and weldabilityInfo
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Description
【０００１】[0001]
【産業上の利用分野】本発明は，各種内燃機関の排ガス
系統用材料あるいは各種燃焼機器などに用いられるフエ
ライト系ステンレス鋼に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferrite stainless steel used for exhaust gas system materials of various internal combustion engines or various combustion devices.
【０００２】[0002]
【従来の技術】近年，自動車あるいは工場から排出され
るガスによる大気汚染が大きな問題となっている。例え
ば自動車の排気ガスは公害防止の観点からＮＯX, ＨＣ,
ＣＯなどの量が規制されてきたが，最近では酸性雨な
どの点からその規制がより厳しくなる傾向にあり, 排気
ガス浄化効率の向上が必要となってきた。2. Description of the Related Art In recent years, air pollution by gas discharged from automobiles or factories has become a serious problem. For example from the viewpoint NO X in the exhaust gas of an automobile pollution control, HC,
Although the amount of CO and the like has been regulated, recently the regulation tends to be stricter due to acid rain and the like, and it is necessary to improve the exhaust gas purification efficiency.
【０００３】他方, 自動車では浄化効率の向上に加え,
エンジンの高出力化あるいは性能アップの要求が高まり
排ガス温度は上昇する傾向にある。このような背景から
排気ガス系統の部材は運転中にきわめて高温になり, ま
た機械の振動や外部からの振動による機械的な応力変
動, あるいは運転パターンに依存した加熱−冷却サイク
ル, さらには寒冷地での冬季温度の低下による温度変動
を受けるなど，きわめて過酷な状況下にさらされること
になる。On the other hand, in automobiles, in addition to improving purification efficiency,
The demand for higher output or higher performance of the engine is increasing, and the exhaust gas temperature tends to increase. Due to this background, the exhaust gas system members become extremely hot during operation, change in mechanical stress due to machine vibration or external vibration, or a heating-cooling cycle depending on the operation pattern, and even in cold regions. It is exposed to extremely severe conditions, such as being subject to temperature fluctuations caused by a decrease in the winter temperature in Japan.
【０００４】ステンレス鋼などの耐熱鋼をこれらの用途
で使用する場合,耐熱性に優れることは無論であるが，
板材あるいはパイプのいずれかを用いても溶接施工を要
するので溶接性に優れることが必要となる。従って, こ
れらの用途では，耐熱性, 低温靭性, 溶接性，加工性を
同時に兼備することが重要な課題となる。When heat-resistant steel such as stainless steel is used in these applications, it is of course excellent in heat resistance.
Even if either a plate material or a pipe is used, welding work is required, so that excellent weldability is required. Therefore, in these applications, it is important to combine heat resistance, low temperature toughness, weldability, and workability at the same time.
【０００５】SUS304に代表されるオーステナイト系ステ
ンレス鋼は加工性に優れ且つ溶接性も良好であるために
上記のような用途に対して有望な材料であると考えられ
ている。しかし, オーステナイト系ステンレス鋼は熱膨
張係数が大きいことから，加熱−冷却を受けるような用
途では使用中に発生する熱応力による熱疲労破壊が懸念
されている。またオーステナイト系ステンレス鋼は熱膨
張係数が大きいことから，加熱−冷却によって表面酸化
物が剥離しやすい。[0005] Austenitic stainless steel represented by SUS304 is considered to be a promising material for the above applications because of its excellent workability and good weldability. However, since austenitic stainless steel has a large coefficient of thermal expansion, there is a concern about thermal fatigue failure due to thermal stress generated during use in applications where heating and cooling are required. Further, since austenitic stainless steel has a large coefficient of thermal expansion, surface oxides are easily peeled off by heating and cooling.
【０００６】このようなことから，この種の用途におい
て一部ではInconel 600に代表されるＮi基の合金が使用
されている。この合金材料は熱膨張係数が低く, また表
面酸化物の密着性など耐高温酸化特性に優れ, 且つ優れ
た高温強度を有しているので有望な材料であるが，極め
て高価な材料であるため広く一般に使用されるには至っ
ていない。For this reason, Ni-based alloys such as Inconel 600 are used in some applications of this type. This alloy material is a promising material because of its low coefficient of thermal expansion, excellent high-temperature oxidation resistance such as adhesion of surface oxides, and excellent high-temperature strength, but it is an extremely expensive material. It has not been widely used.
【０００７】一方, フエライト系ステンレス鋼はオース
テナイト系ステンレス鋼に比べ安価であり, また熱膨張
係数が小さいので熱疲労特性に優れている。従って, 加
熱−冷却の温度サイクルを受ける用途では優れた材料で
あると考えられる。そのためか一部の用途に対してType
409やSUS430で代表されるフエライト系ステンレス鋼が
使用され始めている。しかし，これらの材料は900℃以
上になると強度が著しく低下するため，強度不足による
高温疲労破壊を起こすことや, 耐酸化限界を越えると異
常酸化を起こすなどの問題がある。これらの問題に対
し，ＭoやＣrなどを添加することによって高温強度や高
温酸化特性を改善されることは一般的に知られている
が，かような合金元素の添加は一般に鋼の衝撃靭性を著
しく劣化させまた溶接性および加工性も著しく劣るよう
になるため，使用されるには至っていない。On the other hand, ferritic stainless steel is less expensive than austenitic stainless steel, and has excellent thermal fatigue characteristics due to its small coefficient of thermal expansion. Therefore, it is considered to be an excellent material for applications that undergo a heating-cooling temperature cycle. For that reason or for some applications Type
Ferrite stainless steels such as 409 and SUS430 have begun to be used. However, since the strength of these materials is significantly reduced at 900 ° C or higher, there are problems such as high temperature fatigue failure due to insufficient strength and abnormal oxidation when exceeding the oxidation resistance limit. To solve these problems, it is generally known that the addition of Mo or Cr improves the high-temperature strength and high-temperature oxidation characteristics. However, the addition of such alloy elements generally reduces the impact toughness of steel. It has not been used because it deteriorates remarkably and the weldability and workability also deteriorate remarkably.
【０００８】[0008]
【発明が解決しようとする課題】以上のように，現状で
は高温強度, 耐酸化性, 耐熱性, 靭性, 溶接性, 加工性
といった多様な性質を同時に満足できるような材料は出
現しておらず, 今後の排気ガス浄化効率の向上, 内燃機
関の高出力化および高性能化などの進展とともにますま
す厳しくなる使用条件および環境に対応するため，高温
強度や熱疲労特性および高温酸化などの耐熱性を具有し
たうえ，製造性, 加工性, 溶接性および低温靭性に優れ
た材料が要望されている。もしフエライト系ステンレス
鋼において優れた耐熱性と高温強度を有し且つ製造性,
加工性, 溶接性および低温靭性に優れた鋼が得られれ
ば, 上記のような特殊用途に対して極めて有望な材料を
得ることができるものと考えられる。[Problems to be Solved by the Invention] As described above, at present, there is no material that can simultaneously satisfy various properties such as high-temperature strength, oxidation resistance, heat resistance, toughness, weldability, and workability. In order to cope with increasingly severe use conditions and environments with the improvement of exhaust gas purification efficiency and the increase of output and performance of internal combustion engines in the future, high temperature strength, thermal fatigue characteristics and heat resistance such as high temperature oxidation There is a demand for a material that has excellent manufacturability, workability, weldability and low-temperature toughness. If ferritic stainless steel has excellent heat resistance and high temperature strength,
If a steel with excellent workability, weldability and low-temperature toughness can be obtained, it is expected that a material that is extremely promising for special applications as described above can be obtained.
【０００９】したがって，本発明は，優れた高温強度お
よび耐高温酸化特性を有し, かつフエライト系ステンレ
ス鋼の欠点である低温靭性を改善し，また製造上および
施工上問題となる溶接部の溶接高温割れをも防止したフ
エライト系耐熱用ステンレス鋼の開発を目的としたもの
である。Therefore, the present invention has excellent high-temperature strength and high-temperature oxidation resistance, improves low-temperature toughness which is a disadvantage of ferritic stainless steel, and has a problem in welding of welds which is a problem in production and construction. The purpose is to develop a ferrite heat-resistant stainless steel that also prevents hot cracking.
【００１０】[0010]
【課題を解決するための手段】本発明によれば，重量％
において，Ｃ：0.03％以下，Ｓi：0.1〜0.6％未満，Ｍ
n：0.6〜2.0％，Ｓ：0.006％以下，Ｃr：17.0〜25.0
％，Ｎb：0.2〜0.6％，Ｍo：1.25〜2.5％，Ｃu：0.1〜
0.3％未満，Ｎ：0.03％以下を含み，場合によってはさ
らに，Ａl：0.5％以下，Ｔi：0.5％以下，Ｖ：0.5％以
下，Ｚr：1.0％以下，Ｗ：1.5％以下，Ｂ：0.01％以
下，REM：0.1％以下の１種または２種以上を含有したう
え，前記の範囲において，Ｍn％／Ｓ％の比が200以上
で，且つ 〔Ｎb〕＝Ｎb％−８（Ｃ％＋Ｎ％） の式に従う〔Ｎb〕が0.2以上の関係を満足するようにこ
れらの元素を含有し，残部がＦeおよび製造上の不可避
的不純物からなる耐熱性，低温靱性および溶接性に優れ
たフエライト系耐熱用ステンレス鋼を提供する。According to the present invention, the weight%
, C: 0.03% or less, Si: 0.1 to less than 0.6%, M
n: 0.6 to 2.0%, S: 0.006% or less, Cr: 17.0 to 25.0
%, Nb: 0.2 to 0.6%, Mo: 1.25 to 2.5%, Cu: 0.1 to
Less than 0.3%, N: 0.03% or less, and in some cases, Al: 0.5% or less, Ti: 0.5% or less, V: 0.5% or less, Zr: 1.0% or less, W: 1.5% or less, B: 0.01 % Or less, REM: 0.1% or less, and in the above range, the ratio of Mn% / S% is 200 or more, and [Nb] = Nb% -8 (C% + N %), And these elements are contained so that [Nb] satisfies the relation of 0.2 or more, and the balance is Fe and excellent in heat resistance, low temperature toughness and weldability, which are composed of Fe and inevitable impurities in production. Provide stainless steel for heat resistance.
【００１１】[0011]
【作用】本発明者は前記の目的を達成すべく試験研究を
重ねた結果，以下のような知見を得ることができた。The present inventor has obtained the following findings as a result of repeated studies and studies to achieve the above object.
【００１２】図１は，製品としての靭性を把握するため
にＦe-18％Ｃr-２％Ｍo-0.45％Ｎbを基本組成とした鋼
のシャルピー衝撃靭性に及ぼすＣuの影響を調べた結果
を示したものである。Ｍoを添加すると衝撃値が低下す
ることは従来より知られているが，さらにＣuを複合添
加することにより靭性が改善されるという新しい知見を
得ることができた。このことは重大な知見であり, 冬季
の低温環境化にさらされる部材には特に有効と考えら
れ，今後予想されるますます厳しい条件においても使用
可能となり, フエライト系ステンレス鋼の新しい用途拡
大につながるものと考えられる。FIG. 1 shows the results of examining the effect of Cu on the Charpy impact toughness of a steel having a basic composition of Fe-18% Cr-2% Mo-0.45% Nb in order to grasp the toughness as a product. It is a thing. It has been conventionally known that the addition of Mo lowers the impact value, but a new finding that the toughness is improved by further adding Cu in combination was obtained. This is an important finding and is considered to be particularly effective for components exposed to low-temperature environments in winter, and it can be used under increasingly severe conditions expected in the future, leading to new applications of ferritic stainless steel. It is considered something.
【００１３】図２は，もう一方の重要特性である高温酸
化特性のうち，耐スケール剥離性に及ぼすＭnの影響を
調べたものである。試験はＦe-18％Ｃr-２％Ｍo-0.45％
Ｎbを基本組成としてＭn量を変化させ, 大気中で900℃
および1000℃において100時間の連続酸化を実施し，ス
ケール剥離量を調査した。その結果, いずれの試験温度
でもＭnを0.6％以上添加することによってスケール剥離
が抑制された。従って, Ｍnはフエライト系ステンレス
鋼の耐酸化限界を上昇させるとの知見を得た。FIG. 2 shows the result of examining the effect of Mn on the scale peeling resistance among the high-temperature oxidation characteristics, which is another important characteristic. The test is Fe-18% Cr-2% Mo-0.45%
Change the amount of Mn with Nb as the basic composition, 900 ° C in air
And continuous oxidation was performed at 1000 ℃ for 100 hours, and the scale peeling amount was investigated. As a result, scale peeling was suppressed by adding Mn at 0.6% or more at any test temperature. Therefore, it was found that Mn raises the oxidation resistance limit of ferritic stainless steel.
【００１４】図３は，Ｆe-18％Ｃr-２％Ｍo-0.45％Ｎb
を基本組成とし，図１で効果の認められた適量のＭoと
Ｃuを複合添加したうえ，ＭnとＳを変動させ，溶接高温
割れに及ぼすＭn／Ｓ比の影響を調べたものである。溶
接高温割れは，1.2mm厚の冷延焼鈍板を作成し，40mm×2
00mmの試験片に加工後, 試験片の両端を保持して長手方
向に引張応力を付与した状態にてTIG溶接を行い, 割れ
が発生し始める最小の歪量を臨界歪量とし，これを溶接
高温割れ感受性の指標とした。図３に見られるように，
Ｍo-Ｃu複合添加の場合Ｍn／Ｓが200以上となると臨界
歪量が増大して溶接性が改善される効果が認められた。
この結果，溶接高温割れを改善するためにはＭn／Ｓが2
00以上となる適正量のＭnを添加することが有効である
との知見を得た。FIG. 3 shows that Fe-18% Cr-2% Mo-0.45% Nb
The basic composition is shown in Fig. 1. The effect of the Mn / S ratio on the hot cracking was examined by adding the appropriate amounts of Mo and Cu, which were effective in Fig. 1, and varying the Mn and S. For hot cracking, a cold-rolled annealed sheet of 1.2 mm thickness was prepared and 40 mm x 2
After processing into a 00 mm test piece, TIG welding was performed in a state where both ends of the test piece were held and tensile stress was applied in the longitudinal direction. The minimum strain at which cracking began to occur was defined as the critical strain, and this was defined as the critical strain. It was used as an index of hot cracking susceptibility. As can be seen in FIG.
In the case of Mo-Cu composite addition, when Mn / S is 200 or more, the effect of increasing the critical strain and improving the weldability was recognized.
As a result, Mn / S is required to be 2
It has been found that it is effective to add an appropriate amount of Mn of at least 00.
【００１５】このような知見事実に基づき, 本発明は高
温強度, 熱疲労特性および耐酸化性に優れ, かつ溶接性
および低温靭性に優れたトータルバランスの良好なフエ
ライト系ステンレス鋼を提供するものである。以下に本
発明鋼における各化学成分値の含有量の限定理由の概要
を述べる。Based on these findings, the present invention is to provide a ferrite stainless steel excellent in high-temperature strength, thermal fatigue properties and oxidation resistance, and excellent in weldability and low-temperature toughness and having a good total balance. is there. The outline of the reasons for limiting the content of each chemical component value in the steel of the present invention will be described below.
【００１６】ＣとＮ：ＣとＮは一般的には高温強度を高
めるために重要な元素であるが，反面，含有量が多くな
ると耐酸化性, 加工性ならびに靭性の低下を来す。また
ＣとＮはＮbとの化合物をつくり, フエライト相中の有
効Ｎb量を減少せしめる。したがって, ＣとＮは低いこ
とが望ましく, それぞれ0.03％以下とする。C and N: C and N are generally important elements for increasing the high-temperature strength. On the other hand, as the content increases, the oxidation resistance, workability and toughness decrease. C and N also form a compound of Nb and reduce the effective Nb content in the ferrite phase. Therefore, C and N are desirably low, and each is set to 0.03% or less.
【００１７】Ｓi：Ｓiは耐酸化性の向上には有効な元素
である。しかし，過剰に添加すると硬さが上昇し，加工
性および靭性の低下をもたらすので，0.1〜0.6％未満の
範囲とする。Si: Si is an element effective for improving oxidation resistance. However, if added excessively, the hardness increases and the workability and toughness are reduced, so the content is set in the range of 0.1 to less than 0.6%.
【００１８】Ｍn：Ｍnは前述の試験結果に示したように
溶接高温割れに有害なＳをＭnＳの形で固定し，溶接金
属中のＳを除去, 減少せしめる。Ｓ自身の低減も有効で
あるが，Ｍn／Ｓ≧200以上の関係を満足すれば良好な結
果が得られることが判明した。一方, Ｍnは前述のよう
に耐スケール剥離性の面で0.6％以上添加するとによっ
て耐スケール剥離性が改善される。したがって，Ｍnは
0.6〜2.0％の範囲とし,かつＭn／Ｓ≧200の関係を満足
することが必要である。Mn: Mn fixes S harmful to hot cracking in the form of MnS as shown in the above-mentioned test results, and removes and reduces S in the weld metal. Although reduction of S itself is effective, it has been found that satisfactory results can be obtained if the relationship of Mn / S ≧ 200 is satisfied. On the other hand, as described above, by adding 0.6% or more of Mn in terms of the scale peeling resistance, the scale peeling resistance is improved. Therefore, Mn is
It is necessary to be in the range of 0.6 to 2.0% and to satisfy the relationship of Mn / S ≧ 200.
【００１９】Ｓ：Ｓは上述のごとく溶接高温割れに対し
て有害であるので可能な限り低いほうが望ましいが，低
く押さえるほど製造コストの上昇を招く。本発明鋼にお
いてはＳは0.006％まで許容しても前述のようにＭnの作
用によって十分な耐溶接高温割れを有するのでＳの上限
を0.006％とする。S: As mentioned above, S is harmful to hot cracking of the weld, so it is desirable that S be as low as possible. However, the lower the S, the higher the production cost. In the steel of the present invention, even if S is allowed up to 0.006%, the upper limit of S is set to 0.006% because of sufficient welding hot cracking resistance due to the action of Mn as described above.
【００２０】Ｃr：Ｃrは耐酸化性の改善に不可欠の元素
である。下限を17％としたのは900℃以上の耐酸化性を
維持するためには17％以上の含有を必要とするからであ
る。耐酸化性の面からはＣrは高いほど望ましいが，過
剰に添加すると鋼の脆化を招き, また硬さの上昇によっ
て加工性も劣化するので上限は25％とする。Cr: Cr is an element indispensable for improving the oxidation resistance. The lower limit is set to 17% because a content of 17% or more is required to maintain oxidation resistance of 900 ° C or more. From the standpoint of oxidation resistance, the higher the Cr, the better, but if added excessively, it causes the steel to become brittle, and the workability is also degraded due to the increase in hardness, so the upper limit is 25%.
【００２１】Ｎb：Ｎbは高温強度を維持せしめるのに必
要な元素である。また加工性および耐酸化性の改善や高
周波溶接による造管性にも好影響を及ぼす。後述表２の
高温引張試験結果からもわかるように，高温強度を改善
するためには少なくとも0.2％以上添加する必要があ
る。しかしＮbはＣとＮによる化合物をつくるので，た
だ単に下限を0.2％としてもＣとＮの量によって固溶Ｎb
量は減少し，高温強度に及ぼすＮbの効果は減少する。
したがって 〔Ｎb〕＝Ｎb％−８（Ｃ％＋Ｎ％） の式に従う〔Ｎb〕が0.2％以上となる関係を満足するこ
とが必要である。一方,Ｎbを過剰に添加すると溶接高温
割れ感受性が高くなる。十分な高温強度を維持し，なお
かつ溶接高温割れ感受性に余り影響を及ぼさないように
Ｎbの上限を0.6％とする。Nb: Nb is an element necessary for maintaining high-temperature strength. In addition, it has a favorable effect on the improvement of workability and oxidation resistance, and on the pipe formability by high frequency welding. As can be seen from the results of the high-temperature tensile test shown in Table 2 below, it is necessary to add at least 0.2% or more to improve the high-temperature strength. However, since Nb forms a compound by C and N, even if the lower limit is simply set to 0.2%, the solid solution Nb depends on the amount of C and N.
The amount is reduced and the effect of Nb on the high temperature strength is reduced.
Therefore, it is necessary to satisfy the relationship that [Nb] according to the equation [Nb] = Nb% -8 (C% + N%) is 0.2% or more. On the other hand, when Nb is added excessively, the susceptibility to welding hot cracking increases. The upper limit of Nb is set to 0.6% so as to maintain sufficient high-temperature strength and not significantly affect the susceptibility to welding hot cracking.
【００２２】Ｍo：Ｍoは高温強度を上昇させる。また耐
高温酸化性および耐食性の改善にも有効である。一方，
過剰に添加すると低温での靱性を著しく低下させ，ま
た，製造性および加工性の低下を来すため1.25〜2.5％
とした。Mo: Mo increases the high temperature strength. It is also effective in improving high-temperature oxidation resistance and corrosion resistance. on the other hand,
Excessively markedly reduce the toughness at low temperatures the addition, also for causing a reduction in productivity and workability 1.25 to 2.5%
And
【００２３】Ｃu：Ｃuは前述の試験結果で述べたように
靭性面で非常に有効な元素であり，本発明鋼の重要な元
素である。靭性改善効果を得るためには図１に見られる
ように0.1％以上必要であるため，下限値を0.1％とし
た。一方, 過剰に添加すると硬質となり加工性を害する
ことや,Ｍoが2.5％以下の添加鋼においてはＣu 0.3％以
上において顕著なＣu添加効果が認められないことから,
上限を0.3％未満とする。Cu: Cu is a very effective element in terms of toughness as described in the above test results, and is an important element of the steel of the present invention. Since the effect of improving toughness requires 0.1% or more as shown in FIG. 1, the lower limit is set to 0.1%. On the other hand, if added excessively, it becomes hard and impairs the workability, and in the case of steel containing 2.5% or less of Mo, a remarkable Cu addition effect is not observed at 0.3% or more of Cu.
The upper limit is less than 0.3%.
【００２４】Ａl:Ａlは耐高温酸化特性を改善する。し
かし，過剰に添加すると製造性および溶接性で問題とな
るため上限を0.5％とする。Al: Al improves high temperature oxidation resistance. However, if it is added excessively, it will cause problems in manufacturability and weldability, so the upper limit is made 0.5%.
【００２５】Ｔi:Ｔiは高温強度を上昇させ，加工性も
改善する。しかしＡl同様に過剰添加すると製造性およ
び溶接性で問題となるため，上限を0.5％とする。Ti: Ti increases high-temperature strength and improves workability. However, as in the case of Al, if it is excessively added, there is a problem in productivity and weldability, so the upper limit is made 0.5%.
【００２６】Ｖ：ＶもＴiと同様に高温強度を上昇さ
せ，加工性を改善する。しかし過剰に添加すると加工性
の低下を招く。よって上限を0.5％とする。V: V, like Ti, also increases high-temperature strength and improves workability. However, excessive addition causes a reduction in workability. Therefore, the upper limit is set to 0.5%.
【００２７】Ｚr:Ｚrは高温強度を上昇させ，高温酸化
特性を改善する。しかし，過剰に添加すると加工性の低
下を招くので上限を1.0％とする。Zr: Zr increases high-temperature strength and improves high-temperature oxidation characteristics. However, excessive addition causes a reduction in workability, so the upper limit is made 1.0%.
【００２８】Ｗ：ＷもＴiやＶと同様, 高温強度を上昇
させる。しかし過剰に添加すると加工性の低下を招くの
で上限を1.5％とする。W: Like W and Ti, W also increases the high-temperature strength. However, an excessive addition causes a reduction in workability, so the upper limit is made 1.5%.
【００２９】Ｂ：Ｂは熱間加工性を改善し，高温強度も
上昇させ，加工性をも改善する。しかし過剰に添加する
とかえって熱間加工性の低下を招くため，上限を0.01％
とする。B: B improves hot workability, increases high-temperature strength, and also improves workability. However, excessive addition causes a reduction in hot workability, so the upper limit is 0.01%.
And
【００３０】REM(希土類元素) ：希土類元素は微量添加
によって熱間加工性を改善し，耐酸化性特にスケールの
密着性を改善する。しかし過剰に添加すると逆に熱間加
工性の低下を招くため，上限を0.1％とする。REM (rare earth element): A rare earth element improves hot workability by adding a trace amount thereof, and improves oxidation resistance, in particular, scale adhesion. However, excessive addition will adversely affect hot workability, so the upper limit should be 0.1%.
【００３１】以下に実施例を挙げて本発明鋼の作用効果
を具体的に示す。The working effects of the steel of the present invention will be specifically described below with reference to examples.
【実施例】表１に供試材の化学成分を示した。Ｍ１から
Ｍ13までは本発明鋼で, Ｍ14からＭ16までは比較鋼であ
る。これらの鋼について鋼塊より25mmφの丸棒と, 25mm
厚の板に鍛造した。丸棒は950〜1100℃で焼鈍後, JIS標
準の高温引張試験片に加工した。鍛造板は切削後, 1200
℃抽出による熱間圧延を施し,５mmtの熱延板とし，950
から1100℃で焼鈍後, 一部はそのままでシャルピー衝撃
試験片に加工した。残部は冷延, 焼鈍を繰り返して２mm
tの板厚で高温酸化試験を実施し，1.2mmtの板厚におい
て溶接高温割れ試験を実施した。EXAMPLES Table 1 shows the chemical components of the test materials. M1 to M13 are steels of the present invention, and M14 to M16 are comparative steels. For these steels, a 25mmφ round bar and 25mm
Forged into thick plates. Round bars were annealed at 950-1100 ° C and processed into JIS standard high temperature tensile test specimens. After cutting the forged plate, 1200
Hot-rolled by extraction at ℃ to make a hot-rolled sheet of 5 mm t
After annealing at a temperature of 1100 ° C to 1100 ° C, a part of the sample was processed into a Charpy impact test specimen. The rest is cold-rolled and annealed repeatedly for 2 mm
A high-temperature oxidation test was performed at a thickness of t and a welding hot cracking test was performed at a thickness of 1.2 mm.
【００３２】表２にJISGO567に準じて実施した高温引張
試験による高温引張強さ, 900および1000℃での100時間
の連続酸化試験によるスケール剥離量, 本文に記載した
溶接高温割れ試験による溶接時の臨界歪量, および4.5m
mtの板で実施したシャルピー衝撃試験結果を示した。Table 2 shows the high-temperature tensile strength by a high-temperature tensile test performed according to JISGO567, the amount of scale peeling by a continuous oxidation test at 900 and 1000 ° C. for 100 hours, Critical strain, and 4.5m
showed Charpy impact test results were carried out in a plate of m t.
【００３３】[0033]
【表１】 [Table 1]
【００３４】[0034]
【表２】 [Table 2]
【００３５】表２の結果から明らかなように，本発明鋼
のＭ１〜Ｍ13はＮbおよびＭoを添加することによって高
温強度が上昇し，また，Ｍnを0.6％以上添加することに
よって連続高温酸化試験の900℃および1000℃における
耐スケール剥離性が著しく改善されている。またＭn/Ｓ
を200以上にすることで溶接時の臨界歪量が著しく改善
されている。シャルピー衝撃試験結果では，Ｍoを添加
するにしたがって衝撃靭性は低下するものの，Ｃuを0.1
％以上添加することによって靭性が改善されることがわ
かる。As is evident from the results in Table 2, M1 to M13 of the steels of the present invention have an increased high-temperature strength by adding Nb and Mo, and a continuous high-temperature oxidation test by adding 0.6% or more of Mn. At 900 ° C. and 1000 ° C. has remarkably improved scale peel resistance. Also Mn / S
The critical strain at the time of welding is remarkably improved by setting the ratio to 200 or more. According to the results of the Charpy impact test, although the impact toughness decreases as Mo is added, Cu is reduced to 0.1%.
It can be seen that toughness is improved by adding more than 10%.
【００３６】一方, 比較鋼のＭ14はＭoを添加していな
いため高温強度が本発明鋼に比べ劣る。またＭ15は本発
明鋼に対しＮbの添加量が低いため，高温強度が低いと
ともに, Ｃuを添加していないため本発明鋼のＣu添加材
に比べ衝撃靭性が低く, Ｍn量も低いため高温酸化特性
および溶接時の臨界歪量も劣る。一方Ｍ16はＭnが低い
ため，本発明鋼に対し高温酸化特性および溶接時の臨界
歪量が劣る。On the other hand, M14 of the comparative steel does not contain Mo, and thus has a lower high-temperature strength than the steel of the present invention. In addition, M15 has a low high-temperature strength due to the lower content of Nb in the steel of the present invention, and has a lower impact toughness and a lower Mn content than the Cu-added material of the present steel because Cu is not added. The properties and the critical strain during welding are also poor. On the other hand, since M16 has a low Mn, the high-temperature oxidation characteristics and the critical strain during welding are inferior to those of the steel of the present invention.
【図１】 Ｆe-18％Ｃr-２％Ｍo-0.45％Ｎbを基本組成
とした鋼のシャルピー衝撃靭性に及ぼすＣuの影響を示
す図である。FIG. 1 is a graph showing the effect of Cu on the Charpy impact toughness of steel having a basic composition of Fe-18% Cr-2% Mo-0.45% Nb.
【図２】 Ｆe-18％Ｃr-２％Ｍo-0.45％Ｎbを基本組成
とした鋼のＭn量を変化させ, 大気中で900℃および1000
℃において100時間の連続酸化を実施し，スケール剥離
量を調査した結果を示す図である。[Fig. 2] The Mn content of steel with a basic composition of Fe-18% Cr-2% Mo-0.45% Nb was changed at 900 ° C and 1000 ° C in air.
It is a figure which shows the result of having performed continuous oxidation at 100 degreeC for 100 hours, and having investigated the scale peeling amount.
【図３】 Ｆe-18％Ｃr-２％Ｍo-0.45％Ｎbを基本組成
とし，さらに適量のＭoとＣuを複合添加したうえ，Ｍn
とＳを変動させ，溶接高温割れに及ぼすＭn／Ｓ比の影
響を調べた結果を示す図である。Fig. 3 Basic composition of Fe-18% Cr-2% Mo-0.45% Nb, combined with appropriate amounts of Mo and Cu, and Mn
FIG. 6 is a diagram showing the results of examining the effect of the Mn / S ratio on hot cracking in welding by varying the values of S and S.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中村 定幸 山口県新南陽市野村南町4976番地 日新 製鋼株式会社 鉄鋼研究所内 (56)参考文献 特開 昭64−8254（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 (72) Inventor Sadayuki Nakamura 4976 Nomura Minamicho, Shinnanyo-shi, Yamaguchi Prefecture Nissin Steel Works, Ltd., Steel Research Laboratory (56) References JP-A-64-8254 (JP, A) (58) Field surveyed (Int. Cl. 7 , DB name) C22C 38/00-38/60
Claims (2)
Ｆeおよび製造上の不可避的不純物からなる耐熱性，低
温靱性および溶接性に優れたフエライト系耐熱用ステン
レス鋼。1. C: 0.03% or less, Si: 0.1 to less than 0.6%, Mn: 0.6 to 2.0%, S: 0.006% or less, Cr: 17.0 to 25.0%, Nb: 0.2 to 0.6%, Mo: 1.25 to 2.5%, Cu: less than 0.1 to 0.3%, N: 0.03% or less, provided that the ratio of Mn% / S% is 200 or more and [Nb] = Nb% -8 (C% + N%) Ferrite-based heat-resistant alloys containing these elements so that [Nb] satisfies the relationship of 0.2 or more according to the following formula, and the balance being Fe and inevitable impurities in production, excellent in heat resistance, low-temperature toughness and weldability. Stainless steel.
r：1.0％以下，Ｗ：1.5％ 以下，Ｂ：0.01％以下，REM：0.1％以下の１種または２
種以上を含有したうえ，前記の範囲において Ｍn％／Ｓ％の比が200以上で，且つ 〔Ｎb〕＝Ｎb％−８（Ｃ％＋Ｎ％） の式に従う〔Ｎb〕が0.2以上 の関係を満足するようにこれらの元素を含有し，残部が
Ｆeおよび製造上の不可避的不純物からなる耐熱性，低
温靱性および溶接性に優れたフエライト系耐熱用ステン
レス鋼。2. C: 0.03% or less, Si: 0.1 to less than 0.6%, Mn: 0.6 to 2.0%, S: 0.006% or less, Cr: 17.0 to 25.0%, Nb: 0.2 to 0.6%, Mo: 1.25 to 2.5%, Cu: less than 0.1 to 0.3%, N: 0.03% or less, Al: 0.5% or less, Ti: 0.5% or less, V: 0.5% or less, Z
r: 1.0% or less, W: 1.5% or less, B: 0.01% or less, REM: 0.1% or less 1 or 2
In the above range, the ratio of Mn% / S% is 200 or more, and [Nb] is 0.2 or more according to the formula of [Nb] = Nb% -8 (C% + N%). Ferrite heat-resistant stainless steel containing these elements satisfactorily, the balance being Fe and inevitable impurities in production, and having excellent heat resistance, low-temperature toughness and weldability.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20883491A JP3219099B2 (en) | 1991-07-26 | 1991-07-26 | Ferrite heat-resistant stainless steel with excellent heat resistance, low temperature toughness and weldability |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20883491A JP3219099B2 (en) | 1991-07-26 | 1991-07-26 | Ferrite heat-resistant stainless steel with excellent heat resistance, low temperature toughness and weldability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0533104A JPH0533104A (en) | 1993-02-09 |
| JP3219099B2 true JP3219099B2 (en) | 2001-10-15 |
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| EP1182477A4 (en) | 1999-10-29 | 2005-08-17 | Furukawa Electric Co Ltd | Optical connector housing, optical connector using the optical connector housing and connection structure between optical connector and optical component using the optical connector housing |
| JP5428396B2 (en) * | 2008-03-07 | 2014-02-26 | Ｊｆｅスチール株式会社 | Ferritic stainless steel with excellent heat resistance and weldability |
| JP5462583B2 (en) * | 2008-10-24 | 2014-04-02 | 新日鐵住金ステンレス株式会社 | Ferritic stainless steel sheet for EGR cooler |
| US8764308B2 (en) | 2011-06-06 | 2014-07-01 | Panduit Corp. | Duplex clip assembly for fiber optic connectors |
| JP6037882B2 (en) | 2012-02-15 | 2016-12-07 | 新日鐵住金ステンレス株式会社 | Ferritic stainless steel sheet with excellent scale peel resistance and method for producing the same |
| JP6071608B2 (en) | 2012-03-09 | 2017-02-01 | 新日鐵住金ステンレス株式会社 | Ferritic stainless steel plate with excellent oxidation resistance |
| JP5793459B2 (en) | 2012-03-30 | 2015-10-14 | 新日鐵住金ステンレス株式会社 | Heat-resistant ferritic stainless steel cold-rolled steel sheet excellent in workability, ferritic stainless hot-rolled steel sheet for cold-rolled material, and production method thereof |
| KR101692660B1 (en) | 2013-03-06 | 2017-01-03 | 닛폰 스틸 앤드 스미킨 스테인레스 스틸 코포레이션 | Ferritic stainless steel sheet having excellent heat resistance |
| JP5885884B2 (en) | 2013-03-27 | 2016-03-16 | 新日鐵住金ステンレス株式会社 | Ferritic stainless hot-rolled steel sheet, manufacturing method thereof, and steel strip |
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