JPH07157851A - Corrosion resistant austenitic stainless steel excellent in hot workability - Google Patents

Corrosion resistant austenitic stainless steel excellent in hot workability

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Publication number
JPH07157851A
JPH07157851A JP12517694A JP12517694A JPH07157851A JP H07157851 A JPH07157851 A JP H07157851A JP 12517694 A JP12517694 A JP 12517694A JP 12517694 A JP12517694 A JP 12517694A JP H07157851 A JPH07157851 A JP H07157851A
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JP
Japan
Prior art keywords
weight
hot workability
corrosion resistance
stainless steel
corrosion
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP12517694A
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Japanese (ja)
Other versions
JP2716937B2 (en
Inventor
Yoshihito Fujiwara
Rikio Nemoto
力男 根本
最仁 藤原
Original Assignee
Nippon Yakin Kogyo Co Ltd
日本冶金工業株式会社
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Application filed by Nippon Yakin Kogyo Co Ltd, 日本冶金工業株式会社 filed Critical Nippon Yakin Kogyo Co Ltd
Priority to JP6125176A priority Critical patent/JP2716937B2/en
Publication of JPH07157851A publication Critical patent/JPH07157851A/en
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Publication of JP2716937B2 publication Critical patent/JP2716937B2/en
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Abstract

PURPOSE:To improve the corrosion resistance such as pitting corrosion resistance and crevice corrosion resistance and hot workability of a stainless steel and its oxidation resistance by specifying C, Si, Mn, Cr, Ni, Mo, W or the like and severely regulating the contents of B and O. CONSTITUTION:This stainless steel is formed of a compsn. contg., by weight, <=0.03% C, <=2% Si, <=1% Mn, 19 to 30% Cr, 20 to 30% Ni, 3.5 to 6% Mo, 0.001 to 0.1%B, total <=2% of one or more kinds among W, V and Cu, 0.1 to 0.4% N, <=0.006% 0, <=0.04% P and <=0.005% S, and the balance Fe. Then, in the same ccxnponlnts, the conditions of Cr+3Mo+20N; >=40, Cr+2Mo+8Si+2 Mn+W+3V; <=Ni+Cu+50N+6.4 are satisfied to stabilize its structure.

Description

【発明の詳細な説明】Detailed Description of the Invention
【0001】[0001]
【産業上の利用分野】本発明は、熱間加工性に優れる高
耐食オーステナイトステンレス鋼に関し、特に海水熱交
換器や製紙プラントの漂白プロセス用材料として用いる
ときに好適な、いわゆる耐酸性、耐孔食性や耐すきま腐
食性、なかでも、塩化物による腐食に対して優れた抵抗
性を有すると共に熱間加工性にも優れるステンレス鋼に
ついて提案する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high corrosion resistant austenitic stainless steel excellent in hot workability, and particularly suitable for use as a material for a bleaching process of a seawater heat exchanger or a papermaking plant, so-called acid resistance and pore resistance. We propose stainless steel that has excellent corrosion resistance and crevice corrosion resistance, especially resistance to chloride corrosion, and hot workability.
【0002】[0002]
【従来の技術】近年、耐食材料に要求される品質のレベ
ルは、安全性やメインテナンスフリーによるコストパー
フォーマンスの観点から非常に高くなっており、これに
伴いステンレス鋼も高級化の要請が高まっている。
2. Description of the Related Art In recent years, the level of quality required of corrosion resistant materials has become extremely high from the viewpoint of safety and cost performance due to maintenance-free, and accordingly, there is an increasing demand for higher grade stainless steel. There is.
【0003】かかるステンレス鋼の耐食性については、
孔食、すきま腐食、応力腐食割れ、全面腐食、粒界腐食
等の指標がある。これらの品質指標の中で特に孔食、す
きま腐食は、ステンレス鋼の用途に関連して最も多く直
面する指標であり、特に海水熱交換器などのように塩素
イオン濃度が高く、かつ温度も高くなる環境条件でもこ
れらの耐食性が良好なものが、とりわけ重要である。
Regarding the corrosion resistance of such stainless steel,
There are indicators such as pitting corrosion, crevice corrosion, stress corrosion cracking, general corrosion, and intergranular corrosion. Of these quality indicators, pitting corrosion and crevice corrosion are the most frequently encountered indicators in connection with the use of stainless steel.In particular, the chlorine ion concentration is high and the temperature is high, such as in seawater heat exchangers. It is particularly important that these materials have good corrosion resistance even under the following environmental conditions.
【0004】そこで、従来、耐孔食性やすきま腐食性を
向上させる方法として、CrおよびMo含有量を高くす
ることが知られていた。しかし合金元素としてのCr,
Mo含有量を高くすると、σ相などの金属間化合物が析
出し易く、耐食性の面などで安定した品質が得られがた
くなり、その上、熱間加工性が劣化して製造上の障害に
なるという問題が残る。
Therefore, conventionally, it has been known to increase the Cr and Mo contents as a method of improving pitting corrosion resistance and crevice corrosion resistance. However, Cr as an alloying element,
If the Mo content is increased, intermetallic compounds such as σ phase are likely to precipitate, and it becomes difficult to obtain stable quality in terms of corrosion resistance. In addition, hot workability is deteriorated, which causes an obstacle to manufacturing. The problem remains.
【0005】従って、高Cr高Moを含有する高合金に
ついては、耐食性の他σ相析出に対する組織安定性、熱
間加工性を考慮した総合的な合金設計が必要であり、こ
の意味で上述の既知技術は不充分である。
Therefore, for high alloys containing high Cr and high Mo, it is necessary to comprehensively design the alloy in consideration of corrosion resistance, structural stability against σ phase precipitation, and hot workability. Known techniques are inadequate.
【0006】この点を克服する技術として従来、特公昭
60−23185 号として熱間加工性をも改善したものが提案
されている。しかし、この従来技術も量産化を考えた場
合極めて高い加工性が要求されるので改善の効果はなお
不充分である。
[0006] As a technique for overcoming this point, the Japanese Patent Publication Sho
No. 60-23185, which has improved hot workability, is proposed. However, this conventional technique also requires an extremely high workability in consideration of mass production, and therefore the improvement effect is still insufficient.
【0007】[0007]
【発明が解決しようとする課題】一般に、σ相など金属
間化合物が析出すると、機械的性質の劣化とともに耐食
性も劣化する。従って、オーステナイト組織を安定化さ
せる必要があり、NiやNなどオーステナイト生成元素
を所定量以上含有させねばならない。しかも、工業用材
料としては、耐食性や機械的性質などの品質の他に製造
が容易であることは不可欠な要因であり、特にMoやC
rを多く含有すると熱間加工性が低下するので、量産化
のためにはこの点に関しての解決が必要となるのであ
る。
Generally, when an intermetallic compound such as a σ phase is deposited, not only the mechanical properties deteriorate, but also the corrosion resistance deteriorates. Therefore, it is necessary to stabilize the austenite structure, and austenite forming elements such as Ni and N must be contained in a predetermined amount or more. Moreover, as an industrial material, in addition to qualities such as corrosion resistance and mechanical properties, ease of manufacture is an essential factor, especially Mo and C
If a large amount of r is contained, the hot workability is deteriorated, and therefore a solution to this point is necessary for mass production.
【0008】要するに、本発明はSUS304やSUS316よりも
一段と優れた高Cr, Mo含有の高耐食合金の提案、す
なわち耐食性、σ相析出に対する組織安定性および熱間
加工性のいずれの点においても優れたオーステナイトス
テンレス鋼を提案することを目的としており、特に量産
化に必要な高い熱間加工性を有するオーステナイトステ
ンレス鋼を提供する。
In short, the present invention proposes a highly corrosion-resistant alloy containing high Cr and Mo which is far superior to SUS304 and SUS316, that is, excellent in both corrosion resistance, structural stability against σ phase precipitation and hot workability. The purpose of the invention is to propose an austenitic stainless steel, and particularly to provide an austenitic stainless steel having high hot workability necessary for mass production.
【0009】[0009]
【課題を解決するための手段】本発明は、耐孔食性、耐
すきま腐食性など耐食性に優れかつ、組織的にも異相の
析出が出にくいオーステナイト組織について、さらに熱
間加工性にも優れたものを得ようとする場合に、鋼中の
酸素レベルが低いときBが極めて有効に作用して効果が
あると言う知見に基づいて完成を見たものである。
The present invention is excellent in corrosion resistance such as pitting corrosion resistance and crevice corrosion resistance, and is also excellent in hot workability for an austenitic structure in which precipitation of a different phase is hard to occur in terms of structure. It was completed based on the finding that B is extremely effective and effective when the oxygen level in steel is low when trying to obtain a product.
【0010】すなわち、高Cr高Mo含有鋼だと高温強
度が大きくなり加工性が劣化し、熱間加工時に粒界割れ
が生じ易くなる。しかし、Bを添加するとこのBが粒界
に析出して熱間加工性を向上させる。しかしこのBは、
鋼中の酸素とも結びつき易いため、酸素レベルが高い
と、粒界を強化するフリーBが少なくなり、Bの効果が
充分発揮されなくなる。
That is, if the steel contains a high amount of Cr and a high amount of Mo, the high temperature strength is increased, the workability is deteriorated, and intergranular cracks are likely to occur during hot working. However, when B is added, this B precipitates at the grain boundaries and improves hot workability. But this B is
Since it is easy to combine with oxygen in the steel, if the oxygen level is high, the amount of free B that strengthens the grain boundaries will be small, and the effect of B will not be fully exhibited.
【0011】いわゆる発明者らは、B添加による熱間加
工性に対する効果が、Oレベルによって変わり、それが
60 ppm以下になると著しく向上することを見い出し、次
の事項を骨子とする発明を完成した。
The so-called inventors have found that the effect of B addition on hot workability changes depending on the O level.
It was found that when the concentration was 60 ppm or less, it was remarkably improved, and an invention based on the following matters was completed.
【0012】すなわち、本発明の目的とする所は、C≦
0.030 重量%、Si≦2.0 重量%、Mn≦1.0 重量%、
Cr:19〜30重量%、Ni:20重量%を超え、30重量%
以下、Mo:3.5 重量%を超え、6.0 重量%未満、B:
0.001 〜0.10重量%を含有し、かつ副成分としてW、V
またはCuの少なくとも一種を合計で2.0 重量%以下含
有し、
That is, the object of the present invention is that C ≦
0.030% by weight, Si ≦ 2.0% by weight, Mn ≦ 1.0% by weight,
Cr: 19-30% by weight, Ni: over 20% by weight, 30% by weight
Below, Mo: more than 3.5% by weight and less than 6.0% by weight, B:
Contains 0.001 to 0.10% by weight, and W and V as auxiliary components
Or containing at least 2.0% by weight or less of Cu in total,
【数3】Cr+3Mo+20N≧40 Cr+2Mo+8Si+2Mn+W+3V ≦Ni+Cu+50N+6.4 であり、そしてN:0.10〜0.40重量%、O≦0.0060重量
%、P≦0.040 重量%、S≦0.005 重量%であって、残
部がFeおよび不可避的不純物よりなる熱間加工性に優
れる高耐食オーステナイトステンレス鋼を提供するにあ
る。
## EQU3 ## Cr + 3Mo + 20N ≧ 40 Cr + 2Mo + 8Si + 2Mn + W + 3V ≦ Ni + Cu + 50N + 6.4, and N: 0.10 to 0.40% by weight, O ≦ 0.0060% by weight, P ≦ 0.040% by weight, S ≦ 0.005% by weight, and the balance Fe and unavoidable. To provide a high corrosion resistant austenitic stainless steel which is excellent in hot workability and which is made of mechanical impurities.
【0013】本発明の他の目的とする所は、C≦0.030
重量%、Si≦2.0 重量%、Mn≦1.0 重量%、Cr:
19〜30重量%、Ni:20重量%を超え30重量%以下、M
o:3.5 重量%を超え、6.0 重量%未満、B:0.001 〜
0.010 重量%およびMg≦0.05重量%を含有し、かつ、
W、VまたはCuの少なくとも一種を合計で2.0 重量%
以下含有し、
Another object of the present invention is that C ≦ 0.030.
% By weight, Si ≦ 2.0% by weight, Mn ≦ 1.0% by weight, Cr:
19-30% by weight, Ni: more than 20% by weight and 30% by weight or less, M
o: more than 3.5% by weight and less than 6.0% by weight, B: 0.001 ~
Contains 0.010% by weight and Mg ≦ 0.05% by weight, and
2.0% by weight in total of at least one of W, V and Cu
Contains below,
【数4】Cr+3Mo+20N≧40 Cr+2Mo+8Si+2Mn+W+3V ≦Ni+Cu+50N+6.4 であり、そしてN:0.10〜0.40重量%、O≦0.0060重量
%、P≦0.040 重量%、S≦0.005 重量%であって、残
部がFeおよび不可避的不純物よりなる熱間加工性に優
れる高耐食オーステナイトステンレス鋼を提供するにあ
る。
## EQU4 ## Cr + 3Mo + 20N ≧ 40 Cr + 2Mo + 8Si + 2Mn + W + 3V ≦ Ni + Cu + 50N + 6.4, and N: 0.10 to 0.40% by weight, O ≦ 0.0060% by weight, P ≦ 0.040% by weight, S ≦ 0.005% by weight, and the balance Fe and unavoidable. To provide a high corrosion resistant austenitic stainless steel which is excellent in hot workability and which is made of mechanical impurities.
【0014】また、本発明によれば、上述した高耐食オ
ーステナイトステンレス鋼において、副成分としてMg
を0.05 wt %以下含有させることができる。さらにま
た、副成分として、W,VまたはCuの少なくとも一種
を合計2.0 wt%以下含有させることができ、この場合、
組織の安定性のための条件を
Further, according to the present invention, in the above-mentioned high corrosion resistant austenitic stainless steel, Mg as an auxiliary component
Can be contained in an amount of 0.05 wt% or less. Furthermore, a total of 2.0 wt% or less of at least one of W, V, and Cu can be contained as a subcomponent. In this case,
The conditions for organizational stability
【数5】Cr+2Mo+8Si+2Mn+W+3V ≦Ni+Cu+50N+6.4 とすることが必要である。## EQU5 ## It is necessary to satisfy Cr + 2Mo + 8Si + 2Mn + W + 3V ≦ Ni + Cu + 50N + 6.4.
【0015】[0015]
【作用】以下に本発明オーステナイトステンレス鋼の成
分組成限定の理由について説明する。 C: 0.03 wt % (以下は「%」で略記する) より高い
と、溶接などの熱影響部にクロム炭化物が析出し粒界が
鋭敏化して耐食性が劣化する。 Si:耐孔食性など耐食性に有効ではあるが、2.0 %を
超えると、σ相などの金属間化合物の析出を著しく促進
し、かえって耐食性が劣化したり靭性が劣化する。 Mn : 1.0%を超えると、耐食性が劣化するとともに、
σ相などの析出を促進する。 Cr:耐食性に不可欠の元素で、19%を下廻ると高耐食
合金の特徴が失なわれる。一方、Crはσ相などの生成
を促進し、30%を超えると組織安定化のために高価なN
iなどの多量添加が必要となる。 Ni:σ相など異相の析出を抑える組織安定化元素とし
て極めて有効であり、20%以下になると組織が不安定と
なる。30%を超える添加は高価となる。 Mo:Crと同様に耐食性向上に不可欠な元素である。
その含有量が 3.5%以下になると、本来の耐食性が得ら
れない。しかし、Crと同様、6%以上となるとσ相な
どの異相の析出を促進するので組織安定化のためにNi
が多量に必要となる。 B: 熱間加工性向上に不可欠な元素であり、その効果を
発揮するには、0.001 %以上必要である。また、0.010
%を超えると逆に加工性を劣化させる。 Mg:Sを固定し、熱間加工性を向上する。ただし、0.
05%を超えると、高温で粒界に化合物を析出し逆に加工
性を劣化する。 N: 組織安定化および耐孔食性に極めて有効である。た
だし、0.10重量%より少いと十分な効果が得られず、0.
40%を超える添加は、鋳込み時のブローホールの生成、
高温強度が著しく高くなることによる加工性の劣化をま
ねく。 O:O含有量は、Bの熱間加工性改善効果に重要な影響
があり、B添加のもとでO含有量の限定が重要な意味を
持ってくる。 即ち、本発明合金のような完全オーステナイト組織にお
いてはSなどの不純物元素が粒界に析出し易く、熱間加
工性を劣化するが、B添加により、Sなどの有害な作用
を抑えることができる。これは、高温(熱間加工温度)
でBは、合金中で動き易く、Sが粒界に析出する前にB
が析出して、Sの粒界析出による熱間加工性劣化を抑制
する。しかし、Bは、Oとの親和力も大きく、合金中の
O含有量が高いと、BとOが結びついて、粒界に析出す
るフリーBが少なくなりBの熱間加工性改善効果が軽減
される。即ち、O含有量によって、Bの熱間加工性改善
効果に著しい変化があり、熱間加工性改善に寄与する合
金中のフリーBを確保するためには、O量を低く抑える
必要がある。一方、Oによって固定されるB量を超える
Bの添加により、合金中のフリーBを増加させることが
考えられるが、O含有量が多いとB添加量が増え、Bが
合金中の成分と化合物を形成して、逆に熱間加工性を劣
化させる。従って、熱間加工性を確保するためには、図
2に示すような適正量でBとOとを複合させることが必
要である。したがって、本発明鋼ではBの効果を著しく
高くして極めて優れた熱間加工性を確保するために、O
含有量を0.0060%以下に制限する必要がある。
The function of the compositional limitation of the austenitic stainless steel of the present invention will be described below. If it is higher than C: 0.03 wt% (hereinafter abbreviated as "%"), chromium carbide precipitates in the heat-affected zone of welding and the like, the grain boundaries become sensitive, and the corrosion resistance deteriorates. Si: It is effective for corrosion resistance such as pitting corrosion resistance, but if it exceeds 2.0%, precipitation of intermetallic compounds such as σ phase is remarkably promoted, and on the contrary, corrosion resistance or toughness deteriorates. If Mn exceeds 1.0%, the corrosion resistance deteriorates and
Promotes precipitation of σ phase and the like. Cr: An element indispensable for corrosion resistance. If it is less than 19%, the characteristics of the high corrosion resistance alloy are lost. On the other hand, Cr promotes the formation of σ phase and the like, and if it exceeds 30%, it is expensive N for stabilizing the structure.
It is necessary to add a large amount of i or the like. Ni: It is extremely effective as a microstructure stabilizing element that suppresses the precipitation of different phases such as σ phase, and if it is 20% or less, the microstructure becomes unstable. Addition of more than 30% is expensive. Like Mo: Cr, it is an essential element for improving corrosion resistance.
If the content is less than 3.5%, the original corrosion resistance cannot be obtained. However, similar to Cr, when it is 6% or more, precipitation of a hetero phase such as a σ phase is promoted, and therefore Ni is used for stabilizing the structure.
Is needed in large quantities. B: It is an element indispensable for improving hot workability, and 0.001% or more is necessary to exert its effect. Also, 0.010
If it exceeds%, the workability is deteriorated. Fix Mg: S to improve hot workability. However, 0.
If it exceeds 05%, a compound precipitates at the grain boundary at high temperature and conversely deteriorates workability. N: Very effective in stabilizing the structure and pitting corrosion resistance. However, if it is less than 0.10% by weight, a sufficient effect cannot be obtained, and 0.
Addition of more than 40% creates blowholes during casting,
This leads to deterioration of workability due to extremely high temperature strength. O: The O content has an important influence on the hot workability improving effect of B, and the limitation of the O content under the addition of B has an important meaning. That is, in a completely austenitic structure such as the alloy of the present invention, an impurity element such as S is likely to precipitate at the grain boundaries, deteriorating the hot workability, but the addition of B can suppress the harmful effects of S and the like. . This is a high temperature (hot working temperature)
B is easy to move in the alloy, and before S precipitates at the grain boundaries, B
Precipitates and suppresses deterioration of hot workability due to precipitation of S at grain boundaries. However, B has a large affinity with O, and if the O content in the alloy is high, B and O are bound together, and the amount of free B that precipitates at the grain boundaries is reduced and the effect of improving the hot workability of B is reduced. It That is, there is a significant change in the hot workability improvement effect of B depending on the O content, and it is necessary to keep the O content low in order to secure free B in the alloy that contributes to the hot workability improvement. On the other hand, it is possible to increase the free B in the alloy by adding B in excess of the amount of B fixed by O. However, if the O content is high, the B addition amount increases and B is a component and compound in the alloy. To deteriorate the hot workability. Therefore, in order to secure hot workability, it is necessary to combine B and O in appropriate amounts as shown in FIG. Therefore, in the steel of the present invention, in order to remarkably enhance the effect of B and ensure extremely excellent hot workability, O
It is necessary to limit the content to 0.0060% or less.
【0016】P:Pは 0.040%を超えると熱間加工性、
溶接性が劣化する。 S:Sは 0.005%を超えると熱間加工性、溶接性、耐食
性を著しく劣化させる。Sは好ましくは0.001 %以下が
良い。
P: If P exceeds 0.040%, hot workability,
Weldability deteriorates. S: When S exceeds 0.005%, hot workability, weldability and corrosion resistance are significantly deteriorated. S is preferably 0.001% or less.
【0017】[0017]
【実施例】次に本発明鋼の特性について調べた実施例に
ついて説明する。この実施例で用いた供試材の成分組成
を表1に示す。この供試材(本発明鋼、比較鋼)は、誘
導炉にて10 kg の鋼塊とし、これを熱間鍛造した後焼
鈍、熱間圧延−焼鈍して得た。特性試験は次の方法に従
った。
EXAMPLE Next, an example in which the characteristics of the steel of the present invention were investigated will be described. Table 1 shows the component composition of the test material used in this example. This test material (invention steel, comparative steel) was obtained by hot forging, annealing, and hot rolling-annealing a steel ingot of 10 kg in an induction furnace. The characteristic test was performed according to the following method.
【0018】(1) 熱間加工性評価: (70t× 100w×
l)mm 、10 kg インゴットを1250℃に加熱し、ハンマー
にて10t× 100w×lにし、端部に生じた最大割れ長さ
で評価した。 (2) 組織安定性:(2t)mm板溶体化処理材を10NのKOH
で電解エッチングし、顕微鏡観察により、析出物の量を
格子点法により測定した。 (3) 耐食性
(1) Evaluation of hot workability: (70t × 100w ×
L) mm, 10 kg ingot was heated to 1250 ° C., hammered to 10 t × 100 w × l, and the maximum crack length at the end was evaluated. (2) Structural stability: (2t) mm plate solution treated with 10N KOH
Electrolytic etching was performed, and the amount of precipitates was measured by a lattice point method by observing with a microscope. (3) Corrosion resistance
【数6】 [Equation 6]
【0019】いずれも腐食度で評価した。すきま腐食試
験片を図1に示す。図示の1は輪ゴム、2はガスケット
(テフロン柱)である。以下に試験の結果についてのべ
る。
All were evaluated by the degree of corrosion. A crevice corrosion test piece is shown in FIG. In the figure, 1 is a rubber band, and 2 is a gasket (Teflon column). The test results are given below.
【0020】(1) 熱間加工性について、 表1に示すように、本発明各鋼は、いずれにおいても、
熱間鍛造で割れが発生しておらず: 熱間加工性は極めて
良好であった。一方、比較各鋼においては、ボロンを含
有しない鋼A,Cおよびボロンを含有するが鋼中の酸素
含有量が60 ppmを超える鋼(B,E)あるいは、ボロン
含有量が0.01%を超える鋼(D,F,G)のいずれも割
れが発生している。特に、鋼中酸素含有量が高くなると
加工性の改善に効果のあるボロンが有効に働らかなくな
ることが判った。また、O濃度が60 ppmより低くてもB
を添加しない鋼(I)は割れが発生している。
(1) Regarding hot workability, as shown in Table 1, each of the steels of the present invention is
No cracks occurred during hot forging: Hot workability was extremely good. On the other hand, among the comparative steels, steels A and C that do not contain boron and steels that contain boron but have an oxygen content of more than 60 ppm (B, E) or steels that have a boron content of more than 0.01%. All of (D, F, G) have cracks. In particular, it has been found that when the oxygen content in steel becomes high, boron, which is effective in improving workability, does not work effectively. Also, even if the O concentration is lower than 60 ppm, B
Steel (I) to which is not added has cracks.
【0021】(2) 組織安定性と耐食性について 組織安定性は、鋼に析出したσ相等の析出相量で評価
し、その結果を表1に示す。また、耐食性については表
2にその結果を示す。本発明鋼の場合はいずれも析出相
量は1%以下で低く、耐食性についても孔食試験、すき
ま腐食試験で腐食度は0.1 g/m2・ h以下と低く、全面腐
食試験で2.0 g/m2・ h以下であった。これに対して、比
較鋼は、析出相量は1%を超え、孔食およびすきま腐食
試験の腐食度は0.1 g/m2・h を超えており、耐酸性に対
しても比較鋼A,Bは2g/m2・h を超えていた。
(2) Structural Stability and Corrosion Resistance Structural stability was evaluated by the amount of precipitated phase such as σ phase precipitated in steel, and the results are shown in Table 1. The results of corrosion resistance are shown in Table 2. In the case of the steels of the present invention, the precipitation phase amount is low at 1% or less, and the corrosion resistance is low at 0.1 g / m 2 · h or less in the pitting corrosion test and crevice corrosion test, and 2.0 g / m in the general corrosion test. It was less than m 2 · h. On the other hand, the comparative steel has a precipitation phase amount of more than 1% and a corrosion degree of the pitting and crevice corrosion tests of more than 0.1 g / m 2 · h, and even the acid resistance of the comparative steel A, B exceeded 2 g / m 2 · h.
【0022】図2は、この実施例の鋼について熱間加工
性に及ぼすBおよびO含有量の影響を調べた結果を示す
図で、熱間加工性は、Bおよび酸素量に依存し、Bは加
工性改善に有効であるが0.01%を超えると、逆に加工性
は劣化し、また、O含有量が60 ppmを超えると加工性は
著しく劣化することが確められ、B<0.001 %成分の場
合、酸素(O)が低くても割れが発生することが判る。
FIG. 2 is a diagram showing the results of examining the effect of the B and O contents on the hot workability of the steel of this example. The hot workability depends on B and the oxygen content. Is effective in improving workability, but when it exceeds 0.01%, it is confirmed that the workability deteriorates, and when the O content exceeds 60 ppm, the workability deteriorates significantly. In the case of the components, it can be seen that cracking occurs even if oxygen (O) is low.
【0023】また、図3は、σ析出量に及ぼす各元素の
影響を示す図で、
FIG. 3 is a diagram showing the influence of each element on the σ precipitation amount,
【数7】Cr+2Mo+8Si+2Mn+W+3V> (Cr+Cu+50N+6.4 ) になると析出量は急増することが判った。さらに図4
は、耐食性に及ぼす各元素の影響を調べたもので、Cr
+3Mo+20Nが40%以上で耐食性が良くなることが確
認できた。
[Formula 7] It was found that the precipitation amount rapidly increased when Cr + 2Mo + 8Si + 2Mn + W + 3V> (Cr + Cu + 50N + 6.4). Furthermore, FIG.
Is an investigation of the effect of each element on corrosion resistance.
It was confirmed that the corrosion resistance was improved when + 3Mo + 20N was 40% or more.
【0024】[0024]
【表1】 [Table 1]
【0025】[0025]
【表2】 [Table 2]
【0026】[0026]
【発明の効果】以上説明したように本発明によれば、B
とOの含有量を厳しく調整するという本発明において特
有な合金設計により、耐酸性の他、耐孔食、耐すきま腐
食などの耐食性に優れると共に熱間加工性にも優れたオ
ーステナイトステンレス鋼を工業的に安価に得ることが
できる。
As described above, according to the present invention, B
By the alloy design peculiar to the present invention, in which the contents of O and O are strictly adjusted, austenitic stainless steel which has excellent corrosion resistance such as pitting corrosion and crevice corrosion as well as hot workability in addition to acid resistance is manufactured. Can be obtained at low cost.
【図面の簡単な説明】[Brief description of drawings]
【図1】図1の(a),(b)は、すきま腐食試験片の
正面図および側面図である。
FIG. 1A and FIG. 1B are a front view and a side view of a crevice corrosion test piece.
【図2】図2は、熱間加工性に及ぼすB,Oの影響を示
すグラフである。
FIG. 2 is a graph showing the effects of B and O on hot workability.
【図3】図3は、σ相析出量と各成分組成との関係を示
すグラフである。
FIG. 3 is a graph showing the relationship between the amount of σ phase precipitation and the composition of each component.
【図4】図4は、耐孔食性と各成分組成との関係を示す
グラフである。
FIG. 4 is a graph showing the relationship between pitting corrosion resistance and each component composition.

Claims (2)

    【特許請求の範囲】[Claims]
  1. 【請求項1】 C≦0.030 重量%、Si≦2.0 重量%、
    Mn≦1.0 重量%、Cr:19〜30重量%、Ni:20重量
    %を超え、30重量%以下、Mo:3.5 重量%を超え、6.
    0 重量%未満、B:0.001 〜0.10重量%を含有し、かつ
    副成分としてW、VまたはCuの少なくとも一種を合計
    で2.0 重量%以下含有し、 【数1】Cr+3Mo+20N≧40 Cr+2Mo+8Si+2Mn+W+3V ≦Ni+Cu+50N+6.4 であり、そしてN:0.10〜0.40重量%、O≦0.0060重量
    %、P≦0.040 重量%、S≦0.005 重量%であって、残
    部がFeおよび不可避的不純物よりなる熱間加工性に優
    れる高耐食オーステナイトステンレス鋼。
    1. C ≦ 0.030% by weight, Si ≦ 2.0% by weight,
    Mn ≦ 1.0% by weight, Cr: 19 to 30% by weight, Ni: more than 20% by weight, 30% by weight or less, Mo: more than 3.5% by weight, 6.
    Less than 0% by weight, B: 0.001 to 0.10% by weight, and at least 2.0% by weight or less of W, V or Cu in total as a sub-component, Cr + 3Mo + 20N ≧ 40 Cr + 2Mo + 8Si + 2Mn + W + 3V ≦ Ni + Cu + 50N + 6.4 And N: 0.10 to 0.40% by weight, O ≦ 0.0060% by weight, P ≦ 0.040% by weight, S ≦ 0.005% by weight, the balance being Fe and inevitable impurities, which is excellent in hot workability and has high corrosion resistance. Austenitic stainless steel.
  2. 【請求項2】 C≦0.030 重量%、Si≦2.0 重量%、
    Mn≦1.0 重量%、Cr:19〜30重量%、Ni:20重量
    %を超え30重量%以下、Mo:3.5 重量%を超え、6.0
    重量%未満、B:0.001 〜0.010 重量%およびMg≦0.
    05重量%を含有し、かつ、W、VまたはCuの少なくと
    も一種を合計で2.0 重量%以下含有し、 【数2】Cr+3Mo+20N≧40 Cr+2Mo+8Si+2Mn+W+3V ≦Ni+Cu+50N+6.4 であり、そしてN:0.10〜0.40重量%、O≦0.0060重量
    %、P≦0.040 重量%、S≦0.005 重量%であって、残
    部がFeおよび不可避的不純物よりなる熱間加工性に優
    れる高耐食オーステナイトステンレス鋼。
    2. C ≦ 0.030% by weight, Si ≦ 2.0% by weight,
    Mn ≦ 1.0% by weight, Cr: 19 to 30% by weight, Ni: more than 20% by weight and 30% by weight or less, Mo: more than 3.5% by weight, 6.0
    % By weight, B: 0.001 to 0.010% by weight and Mg ≦ 0.
    05% by weight and at least 2.0% by weight or less of at least one of W, V or Cu, and Cr + 3Mo + 20N ≧ 40 Cr + 2Mo + 8Si + 2Mn + W + 3V ≦ Ni + Cu + 50N + 6.4, and N: 0.10 to 0.40% by weight. , O ≦ 0.0060% by weight, P ≦ 0.040% by weight, S ≦ 0.005% by weight, the balance being Fe and unavoidable impurities, and the high corrosion-resistant austenitic stainless steel excellent in hot workability.
JP6125176A 1994-06-07 1994-06-07 High corrosion resistant austenitic stainless steel with excellent hot workability Expired - Lifetime JP2716937B2 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002069591A (en) * 2000-09-01 2002-03-08 Nkk Corp High corrosion resistant stainless steel
JP2008063597A (en) * 2006-09-05 2008-03-21 Nippon Steel & Sumikin Stainless Steel Corp HIGH Ni-Cr-CONTAINING AUSTENITIC STAINLESS STEEL WIRE ROD

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5295524A (en) * 1976-02-02 1977-08-11 Avesta Jernverks Ab Austenite stainless steel
JPS54141310A (en) * 1978-04-24 1979-11-02 Kobe Steel Ltd Austentic stainless steel with superior corrosion resistance and hot workability
JPS5521547A (en) * 1978-08-01 1980-02-15 Hitachi Metals Ltd Austenite stainless steel having high strength and pitting corrosion resistance
JPS57171651A (en) * 1981-04-15 1982-10-22 Nisshin Steel Co Ltd Perfect austenite stainless steel with superior corrosion resistance at weld zone
JPS59226151A (en) * 1983-06-03 1984-12-19 Kawasaki Steel Corp Austenitic high-alloy stainless steel with superior weldability and hot workability
JPS59226155A (en) * 1983-06-03 1984-12-19 Kawasaki Steel Corp High-alloy stainless steel with high corrosion resistance and superior hot workability

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5295524A (en) * 1976-02-02 1977-08-11 Avesta Jernverks Ab Austenite stainless steel
JPS54141310A (en) * 1978-04-24 1979-11-02 Kobe Steel Ltd Austentic stainless steel with superior corrosion resistance and hot workability
JPS5521547A (en) * 1978-08-01 1980-02-15 Hitachi Metals Ltd Austenite stainless steel having high strength and pitting corrosion resistance
JPS57171651A (en) * 1981-04-15 1982-10-22 Nisshin Steel Co Ltd Perfect austenite stainless steel with superior corrosion resistance at weld zone
JPS59226151A (en) * 1983-06-03 1984-12-19 Kawasaki Steel Corp Austenitic high-alloy stainless steel with superior weldability and hot workability
JPS59226155A (en) * 1983-06-03 1984-12-19 Kawasaki Steel Corp High-alloy stainless steel with high corrosion resistance and superior hot workability

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002069591A (en) * 2000-09-01 2002-03-08 Nkk Corp High corrosion resistant stainless steel
JP2008063597A (en) * 2006-09-05 2008-03-21 Nippon Steel & Sumikin Stainless Steel Corp HIGH Ni-Cr-CONTAINING AUSTENITIC STAINLESS STEEL WIRE ROD

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