JPH0382740A - Duplex stainless steel excellent in hot workability and corrosion resistance - Google Patents

Duplex stainless steel excellent in hot workability and corrosion resistance

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Publication number
JPH0382740A
JPH0382740A JP21965989A JP21965989A JPH0382740A JP H0382740 A JPH0382740 A JP H0382740A JP 21965989 A JP21965989 A JP 21965989A JP 21965989 A JP21965989 A JP 21965989A JP H0382740 A JPH0382740 A JP H0382740A
Authority
JP
Japan
Prior art keywords
corrosion resistance
content
stainless steel
hot workability
less
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.)
Pending
Application number
JP21965989A
Other languages
Japanese (ja)
Inventor
Kunio Kondo
邦夫 近藤
Masakatsu Ueda
昌克 植田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Sumitomo Metal Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sumitomo Metal Industries Ltd filed Critical Sumitomo Metal Industries Ltd
Priority to JP21965989A priority Critical patent/JPH0382740A/en
Publication of JPH0382740A publication Critical patent/JPH0382740A/en
Pending legal-status Critical Current

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Abstract

PURPOSE:To maintain superior corrosion resistance and to provide sufficiently satisfactory hot workability by adding specific amounts of Ca, Mg, and REM to a duplex stainless steel with a prescribed composition and also specifying ferrite content. CONSTITUTION:A duplex stainless steel has a composition consisting of, by weight, <=0.03% C, 0.10-2.0% Si, 0.10-2.0% Mn, <=0.05% P, <=0.002% S, 17.0-30.0% Cr, 1.0-11.0% Ni, 0.10-6.0% Mo, <0.10% Cu, 0.01-0.50% V, 0.01-0.10% Al, 0.01-0.40% N, <=0.0050% O, one or more kinds among 0.0005-0.010% Ca, 0.0005-0.010% Mg, and 0.0005-0.010% REM, and the balance Fe with inevitable impurities. Ferrite content is regulated to 30-70vol.%. Further, small amounts of one or more elements among W, Ti, and Nb are incorporated, if necessary. By this method, superior hot workability and excellent corrosion resistance can be obtained by the reduction in O content and the addition of Ca, Mg, and REM.

Description

【発明の詳細な説明】 〈産業上の利用分野〉 この発明は、オーステナイトとフェライトの2相組織か
ら成るステンレス鋼に関し、特に海水を使用する熱交換
器を始めとした耐海水性が必要とされる化学機器や構造
物、各種化学プラント用配管、ラインパイプ、油井管等
として好適な、熱間加工性及び耐食性に優れる2相ステ
ンレス鋼に関するものである。
[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to stainless steel having a two-phase structure of austenite and ferrite, and is particularly applicable to stainless steels that require seawater resistance, such as heat exchangers that use seawater. The present invention relates to duplex stainless steel that has excellent hot workability and corrosion resistance and is suitable for chemical equipment and structures, piping for various chemical plants, line pipes, oil country tubular goods, etc.

〈従来技術とその課題〉 一般に、“2相ステンレス洞”は耐食性や溶接性に優れ
るばかりか、強度面においてもフェライト系ステンレス
鋼やオーステナイト系ステンレスに勝ることから、近年
、海底フローラインのラインパイプ用鋼等としてその需
要が大きな伸びを示している。
<Prior art and its challenges> In general, "two-phase stainless steel" not only has excellent corrosion resistance and weldability, but also exceeds ferritic stainless steel and austenitic stainless steel in terms of strength. The demand for steel as industrial steel is showing significant growth.

ところが、一方で、上記2相ステンレス鋼はフェライト
相とオーステナイト相の2相組織から成っているため熱
間加工性が芳しくなく、分塊圧延や熱間圧延時に割れや
疵等の欠陥を発生し易くて製造歩留りが非常に悪いと言
う問題を有していた。
However, on the other hand, the above-mentioned duplex stainless steel has a two-phase structure of a ferrite phase and an austenite phase, so its hot workability is poor, and defects such as cracks and flaws occur during blooming and hot rolling. However, the manufacturing yield was very low.

そこで、2相ステンレス鋼の熱間加工性阻害元素たるS
の含有量を極力低減すると共に、固溶されているSをC
aの添加により硫化物として固定して粒界への偏析を抑
え、これによって2相ステンレス鋼の熱間加工性を改善
しようとの提案がなされたく特開昭60−262946
号)。
Therefore, S is an element that inhibits hot workability of duplex stainless steel.
In addition to reducing the content of solid solution S to C as much as possible,
JP-A-60-262946 proposed that the hot workability of duplex stainless steel be improved by fixing it as a sulfide and suppressing its segregation to grain boundaries by adding a.
issue).

しかしながら、上記“Caを添加する手段”によると確
かに熱間加工性が大幅に改善されて製造歩留りの向上が
もたらされるものの、これと引き換えに2相ステンレス
鋼が本来具備していた“優れた耐食性”の低下を招き、
従ってその用途に制限を受けることとなって実用上好ま
しくないとの指摘がなされていた。
However, although it is true that the above-mentioned "means of adding Ca" significantly improves hot workability and improves manufacturing yield, it comes at the cost of improving the "excellent properties" originally possessed by duplex stainless steel. This leads to a decrease in corrosion resistance.
Therefore, it has been pointed out that its use is limited and that it is not practical.

このようなことから、本発明の目的は、本来の優れた耐
食性を維持したままで、かつ十分に満足できる熱間加工
性をも示す2相ステンレス鋼を提供することに置かれた
Therefore, an object of the present invention was to provide a duplex stainless steel that maintains its original excellent corrosion resistance and also exhibits sufficiently satisfactory hot workability.

く課題を解決するための手段〉 本発明者等は、上記目的達成すべく、まず2相ステンレ
ス鋼の熱間加工性改善に著効のあるCa添加がなされた
場合に鋼の耐食性が劣化する原因について調査・検討し
たところ、rCaは固溶Sと結び付いて硫化物を形成す
ると同時に鋼中の○と結合して酸化物を生成する傾向も
強く、従って一層レベル以上のOが存在する鋼中にCa
を添加した場合には酸化物系の介在物が多く形成され、
これが著しい耐食性の低下を招く原因となる」との事実
が明らかとなり、また、該傾向は何もCaに限られるも
のではなく、2相ステンレス鋼の熱間加工性改善に効果
があると推測されるMg、  REM (希土類元素)
等の他の硫化物形成元素を添加したときにも同様である
ことを見出した。
Means for Solving the Problems> In order to achieve the above object, the present inventors first discovered that when Ca is added, which is significantly effective in improving the hot workability of duplex stainless steel, the corrosion resistance of the steel deteriorates. After investigating and examining the cause, it was found that rCa has a strong tendency to combine with solid solution S to form sulfides, and at the same time to combine with ○ in steel to form oxides. niCa
When adding , many oxide-based inclusions are formed,
The fact that "this causes a significant decrease in corrosion resistance" has become clear, and this tendency is not limited to Ca, but is presumed to be effective in improving the hot workability of duplex stainless steel. Mg, REM (rare earth elements)
It was also found that the same effect was obtained when other sulfide-forming elements were added.

更に、本発明者等は、ステンレス鋼の耐食性の評価法と
して「10%Fe(J、・6H,Oの溶液に24時間浸
漬した際にピッティングが発生する温度の高低で判断す
る手法」を導入して硫化物形成元素無添加2相ステンレ
ス鋼と硫化物形成元素添加2相ステンレス鋼の耐食性を
評価すると共に、一般に知られているところのrCr、
 Mo及びNの含有割合(重量%)に基づく式 で算出される“P、 1.”にて評価する手法」をも適
用して同様材料の耐食性を評価し、その結果から「同じ
P、 1.の2相ステンレス調であっても“熱間加工性
の向上を目指してCa、 Mg、  REMの硫化物形
成元素を添加したもの″では“Ca、 Mg、  RE
Mを添加していないもの2に比べて孔食発生温度が著し
く低下する」ことを確認した。
Furthermore, the present inventors have developed a method for evaluating the corrosion resistance of stainless steel by determining the temperature at which pitting occurs when immersed in a solution of 10% Fe (J, 6H, O for 24 hours). In addition to evaluating the corrosion resistance of duplex stainless steel without the addition of sulfide-forming elements and duplex stainless steel with the addition of sulfide-forming elements, the generally known rCr,
The corrosion resistance of the same material was also evaluated by applying the method of evaluating by "P, 1." calculated by the formula based on the content ratio (wt%) of Mo and N, and from the results, "the same P, 1." Even if it is a two-phase stainless steel type with ``sulfide-forming elements such as Ca, Mg, and REM added to improve hot workability'', ``Ca, Mg, and RE''
It was confirmed that the pitting corrosion onset temperature was significantly lower than that of Sample 2, which did not contain M.

そして、これらの結果を踏まえた上で、再度、種々の元
素の2相ステンレス鋼の耐食性に及ぼす影響を総合的に
注意深く検討し、耐食性と熱間加工性を両立させ得る組
成の2相ステンレス鋼の存否について研究を重ねた結果
、 「通常製造されている2相ステンレス鋼においてCan
 Mg或いはREMの添加は何れも熱間加工性の改善に
有効である上、特にO含有量を特定レベルにまで低減す
るとCa、 Mg及びREMの添加がなされたとしても
耐食性を著しく低下させる酸化物系介在物の生成が見ら
れなくなり、加えて鋼中のフェライト含有量割合が特定
の範囲に調整された場合には耐食性改善効果がより一層
安定するようになるが、これらの手段を併用すれば非常
に優れた耐食性と熱間加工性とを兼ね備えた2相ステン
レス鋼の実現が可能である」 との新しい知見に到達することができた。
Based on these results, we comprehensively and carefully examined the effects of various elements on the corrosion resistance of duplex stainless steel, and developed a duplex stainless steel with a composition that achieves both corrosion resistance and hot workability. As a result of repeated research on the existence of Can
The addition of Mg or REM is both effective in improving hot workability, and in particular, when the O content is reduced to a certain level, even if Ca, Mg, and REM are added, oxides that significantly reduce corrosion resistance. If the formation of system inclusions is no longer observed and the ferrite content ratio in the steel is adjusted to a specific range, the corrosion resistance improvement effect will become even more stable, but if these measures are used together, We were able to reach new knowledge that it is possible to create duplex stainless steel that has both extremely excellent corrosion resistance and hot workability.

本発明は、上記知見等に基づいてなされたものであり、 「2相ステンレス鋼を、 C: 0.03%以下(以降、成分割合を表わす%は重
量%とする。
The present invention has been made based on the above-mentioned findings and the like. ``C: 0.03% or less of duplex stainless steel (hereinafter, % representing the component ratio is % by weight).

Si : 0.03%。Si: 0.03%.

Mn : 0.03%、   P:0.05%以下。Mn: 0.03%, P: 0.05% or less.

S : 0.002%以下、   Cr : 17.0
〜30.0%。
S: 0.002% or less, Cr: 17.0
~30.0%.

Ni : 1.0〜11.0%、  門o : 0.1
0〜6.0%。
Ni: 1.0-11.0%, gate o: 0.1
0-6.0%.

Cu : 0.10%未満、    V : 0.01
〜0.50%。
Cu: less than 0.10%, V: 0.01
~0.50%.

Ill: 0.01〜0.10%、   N : 0.
01〜0.40%。
Ill: 0.01-0.10%, N: 0.
01-0.40%.

0 : 0.0050%以下 で、かつ Ca : 0.0005〜0.010%。0: 0.0050% or less So, and Ca: 0.0005-0.010%.

門g : 0.0005〜0.010%。Gate g: 0.0005-0.010%.

RE M : 0.0005〜0.010%のうちの1
種以上を含むか、或いは更にW : 0.01〜1.5
0%、  Ti : 0.01〜0.50%。
REM: 1 out of 0.0005-0.010%
W: 0.01-1.5
0%, Ti: 0.01-0.50%.

Nb : 0.01〜0.50% のうちの1種以上をも含有すると共に、残部がFe及び
不可避的不純物から成る成分組成で、かつフェライト含
有量が30〜70シo1.%に構成することにより、優
れた熱間加工性と耐食性を兼備せしめた点」 に特徴を有している。
Nb: 0.01 to 0.50%, and the balance is Fe and unavoidable impurities, and the ferrite content is 30 to 70%. %, it combines excellent hot workability and corrosion resistance.

ここで、2相ステンレス鋼の各成分含有割合並びにフェ
ライト含有量割合を前記の如くに限定した理由は次の通
りである。
Here, the reason why the content ratio of each component and the ferrite content ratio of the duplex stainless steel are limited as described above is as follows.

く作用〉 A)$、分金含有割 合 Cは鋼中に不可避的に含まれる元素であるが、その含有
量が0.03%を超えた場合には特に溶接熱影響部に炭
化物が析出して耐食性の低下を招くことから、C含有量
は0.03%以下と定めた。
A) $, the metal content C is an element that is unavoidably contained in steel, but if its content exceeds 0.03%, carbides will precipitate, especially in the weld heat affected zone. Therefore, the C content was set at 0.03% or less.

t 十分な耐食性を確保するためには○含有量の低減が欠か
せず、そのため脱酸を目的としたSiの添加が必須とな
る。この場合、Si含有量が0.01%未満では十分な
脱酸効果が得られず、一方、2.0%を超えて含有させ
ると脆化を招くようになることから、Si含有量は0.
03%と定めた。
t In order to ensure sufficient corrosion resistance, it is essential to reduce the ○ content, and therefore it is essential to add Si for the purpose of deoxidation. In this case, if the Si content is less than 0.01%, a sufficient deoxidizing effect cannot be obtained, while if the Si content exceeds 2.0%, it will cause embrittlement. ..
It was set at 0.3%.

Mn Mnは鋼の脱酸と脱硫のために添加される成分であるが
、その含有量が0.10%未満では脱酸・脱硫の効果が
少なく、一方、2.0%を超えて含有量させると耐食性
に悪影響を及ぼすようになることから、Mn含有量は0
.03%と定めた。
Mn Mn is a component added for deoxidizing and desulfurizing steel, but if its content is less than 0.10%, the deoxidizing and desulfurizing effect will be small; on the other hand, if its content exceeds 2.0%, If the Mn content is 0, it will have a negative effect on corrosion resistance.
.. It was set at 0.3%.

ヱ Pは鋼に不可避的に含有されて熱間加工性と耐食性を劣
化させる不純物元素であるので、その含有量は出来るだ
け低いことが好ましいが、脱燐コストとの兼ね合いでP
含有量は0.05%以下と定めた。
Since P is an impurity element that is unavoidably contained in steel and deteriorates hot workability and corrosion resistance, it is preferable to keep its content as low as possible, but considering the cost of dephosphorization,
The content was set at 0.05% or less.

S。S.

Sも綱に不可避的に含有される不純物であり、2相ステ
ンレス鋼の熱間加工性に最も大きく影響する元素である
ため、その含有量は少なければ少ないほど好ましい。そ
して、十分に満足できる熱間加工性を確保するためには
0.002%以下のレベルにまでSを低減する必要があ
ることから、S含有量の上限を0.002%と定めた。
S is also an impurity that is unavoidably contained in steel, and is the element that has the greatest effect on the hot workability of duplex stainless steel, so the lower its content is, the better. In order to ensure sufficiently satisfactory hot workability, it is necessary to reduce S to a level of 0.002% or less, so the upper limit of the S content was set at 0.002%.

Cr Crは2相ステンレス鋼の基本成分の1つであり、耐食
性を支配する重要な成分である。そして、オーステナイ
ト−フェライトの2相組織を呈せしめるには17,0%
以上のCr含有量が必要であるが、その含有量が30.
0%を超えるとσ相が析出し易くなって耐食性と靭性を
劣化するようになることから、Cr含有量は17.0〜
30.0%と定めた。
Cr Cr is one of the basic components of duplex stainless steel and is an important component governing corrosion resistance. In order to exhibit an austenite-ferrite two-phase structure, 17.0%
A Cr content of at least 30% is required.
If it exceeds 0%, the σ phase tends to precipitate, deteriorating corrosion resistance and toughness, so the Cr content should be 17.0~
It was set at 30.0%.

Ni Niは2相組織を得るためにCr含有量、 Mo含有量
並びにN含有量との兼ね合いで添加される成分であるが
、Ni含有量が1.0%未満であるとフェライト相が主
体となって2相組織が得られない。一方、11.0%を
超えてNiを含有させると、今度はオーステナイトを主
体とする相となって2相Mi織が得られないばかりか、
高価な元素であることから経済的な不利を招くことにも
なる。従って、Ni含有量は1.0〜11.0%と定め
た。
Ni Ni is a component added in consideration of the Cr content, Mo content, and N content in order to obtain a two-phase structure, but if the Ni content is less than 1.0%, the ferrite phase becomes the main component. Therefore, a two-phase structure cannot be obtained. On the other hand, if Ni is contained in an amount exceeding 11.0%, the phase will be mainly composed of austenite, and not only will a two-phase Mi weave not be obtained.
Since it is an expensive element, it also causes economic disadvantage. Therefore, the Ni content was determined to be 1.0 to 11.0%.

M。M.

Mo成分には鋼の耐食性を向上させる作用があるが、そ
の含有量が0.1%未満では前記作用による所望の効果
が得られず、一方、6.0%を超えて含有させるとσ相
の析出を著しく促進することから、Mo含有量は0.1
〜6.0%と定めた。
The Mo component has the effect of improving the corrosion resistance of steel, but if the Mo content is less than 0.1%, the desired effect due to the above effect cannot be obtained, while if the Mo content exceeds 6.0%, the σ phase The Mo content is 0.1 because it significantly promotes the precipitation of
It was set at ~6.0%.

Cu Cuは熱間加工性を阻害する元素であるためその混入量
をできるだけ低減する必要があるが、0.10%を下回
る含有量であれば熱間加工性への悪影響が小さいことか
ら、Cu含有量を0.10%未満に制限した。
Cu Cu is an element that inhibits hot workability, so it is necessary to reduce its amount as much as possible, but if the content is less than 0.10%, the negative effect on hot workability is small, so The content was limited to less than 0.10%.

■成分にはCr+Mo等と適量共存させることにより耐
孔食性を向上させる作用があるが、その含有量が0.0
1%未満では前記作用による所望の効果が得られず、一
方、0.50%を超えて含有させると熱間加工性が劣化
することから、■含有量は0.01〜0.50%と定め
た。
■The component has the effect of improving pitting corrosion resistance by coexisting with appropriate amounts of Cr+Mo, etc., but the content is 0.0
If the content is less than 1%, the desired effect due to the above action cannot be obtained, and on the other hand, if the content exceeds 0.50%, hot workability deteriorates. Established.

I Mも脱酸剤として不可欠な成分であり、十分な耐食性を
確保するためにはMの脱酸作用をも利用した。lの低減
が欠かせない。しかし、その含有量が0.01%未満で
は所望の脱酸効果が得られず、一方、0.10%を超え
て含有させるとAINが析出して耐食性の低下を招くよ
うになることから、A1含有量は0.01〜o、io%
と定めた。
IM is also an essential component as a deoxidizing agent, and the deoxidizing action of M was also utilized to ensure sufficient corrosion resistance. It is essential to reduce l. However, if the content is less than 0.01%, the desired deoxidizing effect cannot be obtained, while if the content exceeds 0.10%, AIN will precipitate, leading to a decrease in corrosion resistance. A1 content is 0.01~o,io%
It was determined that

旦 Nは2相組織を形成するのに重要な成分てあり、耐食性
の向上にも有効であるが、N含有量が0.01%未満で
は上記効果が乏しく、一方、0.40%を超えて含有さ
せると熱間加工性が低下する上、鋳造時にブローホール
ができ易くなることから、N含有量は0.01〜0.4
0%と限定した。
N is an important component in forming a two-phase structure and is also effective in improving corrosion resistance, but if the N content is less than 0.01%, the above effect is poor, while if it exceeds 0.40%. N content is 0.01 to 0.4 because hot workability decreases and blowholes are more likely to form during casting.
It was limited to 0%.

Ca  阿  びREM() CaやMg、或いはLa、Ce等のREMは何れも鋼中
で硫化物を生成してSを固定し、鋼の熱間加工性を向上
させる作用を有しているのでこれらのうちの1種又は2
種以上の添加が必須であるが、何れも含有量が0.00
05%未満では前記作用による所望の効果が得られず、
一方、0.010%を超えて含有させても上記効果が飽
和してしまうことから、Ca。
Ca and REM () Ca, Mg, La, Ce, and other REMs all have the effect of generating sulfides in steel, fixing S, and improving the hot workability of steel. One or two of these
It is essential to add seeds or more, but the content of each is 0.00
If it is less than 0.05%, the desired effect due to the above action cannot be obtained,
On the other hand, since the above effect is saturated even if Ca is contained in an amount exceeding 0.010%.

陶又はREMの含有量はそれぞれo、ooos〜o、o
t。
The content of ceramic or REM is o, ooos ~ o, o, respectively.
t.

%と定めた。%.

J−ユL」1L匹 これらの成分には何れも綱の耐食性を改善する作用があ
るので、必要によりこれらのうちの1種又は2種以上の
添加がなされるが、以下、個々の成分毎にその含有量範
囲を限定した理由を説明する。
Since all of these ingredients have the effect of improving the corrosion resistance of the steel, one or more of these may be added as necessary, but each individual ingredient will be described below. The reason for limiting the content range will be explained below.

a) W Cr、 Moと共に適量添加されると局部腐食性の向上
効果が得られるが、その含有量が0.01%未満では所
望の効果が確保できず、一方、1.50%を超えて含有
させると熱間加工性の低下を招くようになることから、
W含有量は0.01〜1.50%と定めた。
a) When added in an appropriate amount together with W Cr and Mo, the effect of improving local corrosion properties can be obtained, but if the content is less than 0.01%, the desired effect cannot be ensured, while on the other hand, if the content exceeds 1.50% If it is included, it will lead to a decrease in hot workability, so
The W content was determined to be 0.01 to 1.50%.

b) Tt、及びNb これらの元素は鋼中で安定な炭化物を生成して耐食性の
向上に寄与するが、何れも0.01%未満では十分な効
果が得られず、一方、何れも0.50%を超えて含有さ
せても上記効果が飽和してしまうことから、Ti含有量
並びにNb含有量は0.01〜0.50%と定、めた。
b) Tt and Nb These elements generate stable carbides in steel and contribute to improving corrosion resistance, but if any of them is less than 0.01%, a sufficient effect cannot be obtained; Since the above effect is saturated even if the content exceeds 50%, the Ti content and Nb content were determined to be 0.01 to 0.50%.

OはCaやLEM等と化合物を作り易く、容易に酸化物
系の介在物となって耐食性を低下させる好ましくない不
純物元素であって、所望の耐食性を確保するためにはそ
の含有量を0.0050%以下に低減する必要がある。
O is an undesirable impurity element that easily forms compounds with Ca, LEM, etc., and easily becomes oxide inclusions that reduce corrosion resistance. It is necessary to reduce it to 0.050% or less.

そして、耐食性の面からは0含有量は低いほど良く、出
来ればo、ooao%以下にまで低減することが望まし
い。
From the viewpoint of corrosion resistance, the lower the 0 content, the better, and it is desirable to reduce it to 0, ooao% or less if possible.

B)フェライト含有量 フェライト量が30vo1.%未満或いは70シol。B) Ferrite content The amount of ferrite is 30vol. % or less than 70 sills.

%を超える場合には所望の耐食性を確保することができ
ないことから、2相ステンレス鋼中のフェライト含有量
を30〜70vo1.%と限定した。
%, the desired corrosion resistance cannot be secured, so the ferrite content in the duplex stainless steel is set to 30 to 70 vol. %.

なお、上記フェライトIの割合は、本発明の規定範囲内
で各成分の含有割合を調整して達成することができる。
Note that the above ratio of ferrite I can be achieved by adjusting the content ratio of each component within the specified range of the present invention.

続いて、この発明を実施例により、比較例と対比しなが
ら更に具体的に説明する。
Next, the present invention will be described in more detail using Examples and in comparison with Comparative Examples.

〈実施例〉 まず、高周波誘導真空溶解炉で第1表に示す如き成分組
成の各2相ステンレス鋼を溶製し、50kgの鋼塊に鋳
込んだ。
<Example> First, each duplex stainless steel having the composition shown in Table 1 was melted in a high frequency induction vacuum melting furnace and cast into a 50 kg steel ingot.

次いで、これら鋼塊を121m厚にまで熱間圧延した後
、r1070℃に30分間加熱・保持後水冷」なる条件
の溶体化処理を施し、このようにして得られた各板材の
フェライト(α)量を調査すると共に、該板材から2f
l厚X2Qm幅X50tm長の腐食試験片と10mφX
130ts長の高温高速引張試験片を採取してそれぞれ
の試験に供した。
Next, these steel ingots were hot-rolled to a thickness of 121 m, and then subjected to solution treatment under the following conditions: heating and holding at r1070°C for 30 minutes, followed by water cooling, and the ferrite (α) of each plate thus obtained was In addition to investigating the amount, 2f from the board material
Corrosion test piece with l thickness x 2Qm width x 50tm length and 10mφ
High-temperature, high-speed tensile test pieces with a length of 130 ts were taken and used for each test.

なお、腐食試験は、上記腐食試験片を各種温度の10%
F e Cj s・6H,O水溶液に24時間浸漬して
試験片表面にビンティングが生じる最低の温度を調査し
、該温度を“限界ビンティング温度(C,P、T、)”
としてそれの高いものを高耐食性と評価する方法によっ
た。但し、ステンレス鋼の耐食性の程度がほぼCr、 
N及びMoの各元素の含有量に支配されることは良く知
られており、既に述べたように耐食性のレベルが P、1.=Cr(X)+ 3Mo(り+16N(Z)で
ほぼ整理できることからこれまで上記P、1.が耐食性
の指標とされてきた点も考慮し、この実施例においても
耐食性の評価はP、■、を加味したC、P、?。
In addition, in the corrosion test, the above corrosion test piece was heated to 10% of various temperatures.
The lowest temperature at which binning occurs on the surface of the test piece after immersion in an aqueous solution of F e Cj s 6H, O for 24 hours was investigated, and this temperature was determined as the "limit binning temperature (C, P, T,)".
According to the method, those with higher corrosion resistance are evaluated as having high corrosion resistance. However, the degree of corrosion resistance of stainless steel is almost Cr,
It is well known that the level of corrosion resistance is controlled by the content of each element of N and Mo, and as already mentioned, the level of corrosion resistance is determined by the content of each element, P, 1. =Cr(X)+3Mo(Ri+16N(Z)) Considering that P, 1. above has been used as an index of corrosion resistance, the evaluation of corrosion resistance in this example is P, , C, P, ?.

の高低を基に行った。Based on the height of

また、高温高速引張試験は熱間加工性の評価のために実
施したものであるが、“歪速度:1.Os −”で90
0℃、1000℃、1100℃、1200℃の各温度で
引張破断させた時の絞り値がすべて70%以上を示すも
の”が実際の熱間圧延においても十分な加工性を示して
良好な表面性状を呈することから、上記絞り値がすべて
の温度で70%以上のものを良好(○)、いずれかの温
度で70%未満を示すものを不良(×)と評価した。
In addition, the high-temperature high-speed tensile test was conducted to evaluate hot workability, and the strain rate was 90 at a strain rate of 1.Os.
Those that exhibit a reduction of area of 70% or more when subjected to tensile fracture at 0°C, 1000°C, 1100°C, and 1200°C exhibit sufficient workability even in actual hot rolling and have a good surface. In terms of properties, those whose aperture value was 70% or more at all temperatures were evaluated as good (◯), and those whose aperture value was less than 70% at any temperature were evaluated as poor (x).

これらの結果を第2表に示す。These results are shown in Table 2.

第2表に示される結果からも明らかなように、本発明に
係る2相ステンレス鋼は、熱間加工性が良好であるばか
りでなく、耐食性試験結果をP、 1とC,P、T、と
の関係でグラフ化した第1図にて確認できる通り、従来
鋼や比較鋼と同じP、1.であってもこれより遥かに高
いC,P、T、を示していて一段と優れた耐食性を有し
ていることが分かる。なお、第1図中の記号に付した数
字は、第1表の鋼種番号を示している。
As is clear from the results shown in Table 2, the duplex stainless steel according to the present invention not only has good hot workability, but also has corrosion resistance test results of P, 1, C, P, T, As can be seen in Figure 1, which is a graph showing the relationship between P and 1. Even so, it shows much higher C, P, and T than this, and it can be seen that it has even better corrosion resistance. Note that the numbers attached to the symbols in FIG. 1 indicate the steel type numbers in Table 1.

これに対して、従来鋼16〜21もCa、 Mg、  
REM等の硫化物生成元素が添加されて良好な熱間加工
性を有しているが、0量の低減が十分でないので本発明
鋼と比較してp、r、の割にはC,P、T、が低レベル
となっており、熱間加工性と耐食性が共に優れていると
は言い難い。
On the other hand, conventional steels 16 to 21 also contain Ca, Mg,
Although it has good hot workability due to the addition of sulfide-forming elements such as REM, the reduction in the amount of 0 is not sufficient, so compared to the steel of the present invention, C and P are reduced in terms of p and r. , T are at low levels, and it is difficult to say that both hot workability and corrosion resistance are excellent.

また、比較鋼22.23は、それぞれフェライト分率が
本発明で規定する範囲から外れているため耐食性に劣る
結果となっている。
Furthermore, Comparative Steels 22 and 23 had inferior corrosion resistance because their ferrite fractions were outside the range defined by the present invention.

そして、比較鋼24はP量が過剰であるため耐食性が十
分でなく、比較鋼25はS量が過剰なために熱間加工性
に劣り、更に比較鋼26は、硫化物生成元素たるCa、
 Mg或いはREMの添加がなされていないため耐食性
は良好であるものの熱間加工性が不十分な結果となって
いる。
Comparative steel 24 has insufficient corrosion resistance due to an excessive amount of P, comparative steel 25 has poor hot workability due to an excessive amount of S, and furthermore, comparative steel 26 has Ca, which is a sulfide-forming element,
Since no Mg or REM was added, the corrosion resistance was good, but the hot workability was insufficient.

く効果の総括〉 以上に説明した如く、この発明によれば、耐食性並びに
熱情加工性が共に優れた2相ステンレス鋼を実現するこ
とが可能となり、“海底フローライン用ラインパイプ等
の耐食性(耐海水性等)が重視される用途で熱間加工性
を犠牲にして製造歩留りの大幅な低下を余儀無くされて
いた2相ステン。
Summary of Effects> As explained above, according to the present invention, it is possible to realize a duplex stainless steel that has excellent corrosion resistance and heat workability, and improves the corrosion resistance of line pipes for submarine flow lines, etc. Dual-phase stainless steel has been forced to sacrifice hot workability and significantly reduce manufacturing yield in applications where compatibility (seawater, etc.) is important.

レス鋼に絡む従来の問題”が−挙に解決できるなど、産
業上図り知れない効果がもたらされる。
It brings about unprecedented industrial effects, such as being able to solve all the conventional problems associated with non-resistance steel.

【図面の簡単な説明】[Brief explanation of drawings]

第1図は、耐食性試験結果をp、 r、とC,P、T、
との関係で表わしたグラフである。
Figure 1 shows the corrosion resistance test results for p, r, C, P, T,
This is a graph expressed in relation to

Claims (2)

【特許請求の範囲】[Claims] (1)重量割合にて C:0.03%以下,Si:0.10〜2.0%,Mn
:0.10〜2.0%,P:0.05%以下,S:0.
002%以下,Cr:17.0〜30.0%,Ni:1
.0〜11.0%,Mo:0.10〜6.0%,Cu:
0.10%未満,V:0.01〜0.50%,Al:0
.01〜0.10%,N:0.01〜0.40%,O:
0.0050%以下 で、かつ Ca:0.0005〜0.010%, Mg:0.0005〜0.010%, REM:0.0005〜0.010% のうちの1種以上をも含有すると共に、残部がFe及び
不可避的不純物から成り、かつフェライト含有量が30
〜70vol.%であることを特徴とする、熱間加工性
と耐食性の優れた2相ステンレス鋼。
(1) C: 0.03% or less, Si: 0.10-2.0%, Mn in weight percentage
: 0.10-2.0%, P: 0.05% or less, S: 0.
002% or less, Cr: 17.0-30.0%, Ni: 1
.. 0-11.0%, Mo: 0.10-6.0%, Cu:
Less than 0.10%, V: 0.01-0.50%, Al: 0
.. 01-0.10%, N: 0.01-0.40%, O:
0.0050% or less, and also contains one or more of Ca: 0.0005 to 0.010%, Mg: 0.0005 to 0.010%, and REM: 0.0005 to 0.010%. In addition, the remainder consists of Fe and unavoidable impurities, and the ferrite content is 30
~70vol. % duplex stainless steel with excellent hot workability and corrosion resistance.
(2)重量割合にて C:0.03%以下,Si:0.10〜2.0%,Mn
:0.10〜2.0%,P:0.05%以下,S:0.
002%以下,Cr:17.0〜30.0%,Ni:1
.0〜11.0%,Mo:0.10〜6.0%,Cu:
0.10%未満,V:0.01〜0.50%,Al:0
.01〜0.10%,N:0.01〜0.40%,O:
0.0050%以下 で、かつ Ca:0.0005〜0.010%, Mg:0.0005〜0.010%, REM:0.0005〜0.010% のうちの1種以上、並びに W:0.01〜1.50%,Ti:0.01〜0.50
%,Nb:0.01〜0.50% のうちの1種以上をも含有すると共に、残部がFe及び
不可避的不純物から成り、かつフェライト含有量が30
〜70vol.%であることを特徴とする、熱間加工性
と耐食性の優れた2相ステンレス鋼。
(2) C: 0.03% or less, Si: 0.10-2.0%, Mn in weight percentage
: 0.10-2.0%, P: 0.05% or less, S: 0.
002% or less, Cr: 17.0-30.0%, Ni: 1
.. 0-11.0%, Mo: 0.10-6.0%, Cu:
Less than 0.10%, V: 0.01-0.50%, Al: 0
.. 01-0.10%, N: 0.01-0.40%, O:
0.0050% or less, and one or more of Ca: 0.0005-0.010%, Mg: 0.0005-0.010%, REM: 0.0005-0.010%, and W: 0.01-1.50%, Ti: 0.01-0.50
%, Nb: 0.01 to 0.50%, the balance consists of Fe and unavoidable impurities, and the ferrite content is 30%.
~70vol. % duplex stainless steel with excellent hot workability and corrosion resistance.
JP21965989A 1989-08-25 1989-08-25 Duplex stainless steel excellent in hot workability and corrosion resistance Pending JPH0382740A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP21965989A JPH0382740A (en) 1989-08-25 1989-08-25 Duplex stainless steel excellent in hot workability and corrosion resistance

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP21965989A JPH0382740A (en) 1989-08-25 1989-08-25 Duplex stainless steel excellent in hot workability and corrosion resistance

Publications (1)

Publication Number Publication Date
JPH0382740A true JPH0382740A (en) 1991-04-08

Family

ID=16738965

Family Applications (1)

Application Number Title Priority Date Filing Date
JP21965989A Pending JPH0382740A (en) 1989-08-25 1989-08-25 Duplex stainless steel excellent in hot workability and corrosion resistance

Country Status (1)

Country Link
JP (1) JPH0382740A (en)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0593246A (en) * 1991-09-30 1993-04-16 Sumitomo Metal Ind Ltd Highly corrosion resistant duplex stainless steel and its production
JPH0741907A (en) * 1993-07-28 1995-02-10 Nippon Yakin Kogyo Co Ltd Superplastic two-phase stainless steel
JPH0741906A (en) * 1993-07-28 1995-02-10 Nippon Yakin Kogyo Co Ltd Superplastic two-phase stainless steel
KR100444248B1 (en) * 2001-04-27 2004-08-16 한국산업기술평가원 High manganese duplex stainless steel having superior hot workabilities and method for manufacturing thereof
WO2006071027A1 (en) * 2004-12-27 2006-07-06 Posco Duplex stainless steel having excellent corrosion resistance with low nickel
KR100694312B1 (en) * 2005-12-19 2007-03-14 포스코신기술연구조합 A high ni duplex stainless steel improving hot-workability for welding rod
CN102162063A (en) * 2010-02-23 2011-08-24 宝山钢铁股份有限公司 Ferritic stainless steel medium plate and manufacturing method thereof
JP2011202247A (en) * 2010-03-26 2011-10-13 Nippon Steel & Sumikin Stainless Steel Corp Two-phase stainless steel material having excellent corrosion resistance
JP2012140689A (en) * 2011-01-06 2012-07-26 Sanyo Special Steel Co Ltd Duplex stainless steel excellent in toughness
JP2013204044A (en) * 2012-03-27 2013-10-07 Nippon Steel & Sumikin Stainless Steel Corp Duplex stainless steel with high weldability
JP2014074209A (en) * 2012-10-05 2014-04-24 Kobe Steel Ltd Duplex stainless steel material and duplex stainless steel pipe
JP2016003377A (en) * 2014-06-18 2016-01-12 新日鐵住金株式会社 Two-phase stainless steel tube

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0593246A (en) * 1991-09-30 1993-04-16 Sumitomo Metal Ind Ltd Highly corrosion resistant duplex stainless steel and its production
JPH0741907A (en) * 1993-07-28 1995-02-10 Nippon Yakin Kogyo Co Ltd Superplastic two-phase stainless steel
JPH0741906A (en) * 1993-07-28 1995-02-10 Nippon Yakin Kogyo Co Ltd Superplastic two-phase stainless steel
KR100444248B1 (en) * 2001-04-27 2004-08-16 한국산업기술평가원 High manganese duplex stainless steel having superior hot workabilities and method for manufacturing thereof
US8043446B2 (en) 2001-04-27 2011-10-25 Research Institute Of Industrial Science And Technology High manganese duplex stainless steel having superior hot workabilities and method manufacturing thereof
JP2008525636A (en) * 2004-12-27 2008-07-17 ポスコ Nickel reduced type high corrosion resistance duplex stainless steel
EP1838890A1 (en) * 2004-12-27 2007-10-03 Posco Duplex stainless steel having excellent corrosion resistance with low nickel
EP1838890A4 (en) * 2004-12-27 2008-02-20 Posco Duplex stainless steel having excellent corrosion resistance with low nickel
WO2006071027A1 (en) * 2004-12-27 2006-07-06 Posco Duplex stainless steel having excellent corrosion resistance with low nickel
KR100694312B1 (en) * 2005-12-19 2007-03-14 포스코신기술연구조합 A high ni duplex stainless steel improving hot-workability for welding rod
CN102162063A (en) * 2010-02-23 2011-08-24 宝山钢铁股份有限公司 Ferritic stainless steel medium plate and manufacturing method thereof
JP2011202247A (en) * 2010-03-26 2011-10-13 Nippon Steel & Sumikin Stainless Steel Corp Two-phase stainless steel material having excellent corrosion resistance
JP2012140689A (en) * 2011-01-06 2012-07-26 Sanyo Special Steel Co Ltd Duplex stainless steel excellent in toughness
JP2013204044A (en) * 2012-03-27 2013-10-07 Nippon Steel & Sumikin Stainless Steel Corp Duplex stainless steel with high weldability
JP2014074209A (en) * 2012-10-05 2014-04-24 Kobe Steel Ltd Duplex stainless steel material and duplex stainless steel pipe
JP2016003377A (en) * 2014-06-18 2016-01-12 新日鐵住金株式会社 Two-phase stainless steel tube

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