JP2007063632A - Austenitic stainless steel - Google Patents
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本発明は、冷間加工性および耐食性において、SUS304と同等の性能を有し、しかも熱間圧延時の耳割れを起こしにくく、冷間圧延性もSUS304と同等の特性を有し、SUS304と類似した用途に使用できる安価なMn添加オーステナイト系ステンレス鋼に関するものである。 The present invention has the same performance as SUS304 in cold workability and corrosion resistance, is less likely to cause ear cracking during hot rolling, has cold rolling properties similar to SUS304, and is similar to SUS304. The present invention relates to an inexpensive Mn-added austenitic stainless steel that can be used for various purposes.
SUS304を代表とするオーステナイト系ステンレス鋼は、冷間加工性や耐食性に優れ、様々な製品が様々な用途・環境で使用されている。しかし、これらに代表されるオーステナイト系ステンレス鋼は、一般に高価なNi原料が多く使用されている。このため、Ni資源の不足に基づく需給バランスの崩れや一部では投機対象による価格不安定性が発生している。これはオーステナイト系ステンレス鋼の生産において、常につきまとう大きな問題である。 Austenitic stainless steel represented by SUS304 is excellent in cold workability and corrosion resistance, and various products are used in various applications and environments. However, austenitic stainless steels represented by these generally use a lot of expensive Ni raw materials. For this reason, the supply-demand balance has collapsed due to the shortage of Ni resources, and in part, price instability has occurred due to speculation. This is always a major problem in the production of austenitic stainless steel.
そこで、この問題を解決するため、オーステナイト系ステンレス鋼のNiをMnやNで代替する研究が従来から行われており、これまでに200系ステンレスをはじめ、製造メーカーの独自鋼種としていくつか知られている。これらは、NiをMnやNで代替するため、上述した価格面での不安定性はある程度解消されるものの、その性質は万能なSUS304に及ばないことが多い。 In order to solve this problem, research to replace Ni in the austenitic stainless steel with Mn or N has been conducted in the past, and several known steel types such as 200 series stainless steel have been known so far. ing. Since these replace Ni with Mn or N, the above-mentioned price instability is resolved to some extent, but the properties are often not as good as those of universal SUS304.
例えばこれら代替鋼種は製造性、特に、熱間圧延時の耳割れや冷間圧延時のパス増など、実際の製造において、歩留まりの低下や生産性の低下などが発生し、原料コスト減ほど安価にならないなどの問題がある。 For example, these alternative steel grades are less expensive as the raw material cost decreases due to the decrease in yield, productivity, etc. in actual production, such as manufacturability, especially cracking during hot rolling and increased passes during cold rolling. There are problems such as not becoming.
Mnを多く含有したオーステナイト系ステンレス鋼の熱間加工性を改善した例として、特開平３−２３５７号がある。ここでは、3.5％を越えるCu添加による低融点のMn−Cu相、またはCu相の存在が熱間加工性を低下させるとし、Mn、Cu等の添加範囲を限定しているが、その改善効果は十分とは言えず、熱間圧延時の耳割れの問題が依然と解消されていなかった。
本発明はこのような状況に鑑み、製造性および耐食性において、SUS304と同等の安価なMn添加オーステナイト系ステンレス鋼を提供することを課題とする。 In view of such circumstances, an object of the present invention is to provide an inexpensive Mn-added austenitic stainless steel equivalent to SUS304 in terms of manufacturability and corrosion resistance.
本発明者らは、オーステナイト系ステンレス鋼の合金組成と、製造性および耐食性との関係を種々研究した結果、Mn、Cu、Nの適当量の代替によって、良好な熱間加工性を維持しつつNiを減じ得る範囲を見出し、更に、δフェライト量、N及びS含有量と熱間加工性の関係を明らかにし、本発明に到った。 As a result of various studies on the relationship between the alloy composition of austenitic stainless steel, manufacturability and corrosion resistance, the present inventors have maintained good hot workability by substituting appropriate amounts of Mn, Cu and N. The inventors have found a range where Ni can be reduced, and further clarified the relationship between the amount of δ ferrite, the contents of N and S, and hot workability, and have reached the present invention.
即ち、本発明は、重量％で、C≦0.10％、Si≦1.0％、P≦0.10％、S≦0.010％、3.0％≦Mn≦7.0％、2.0％≦Ni≦5.0％、16.0％≦Cr≦20.0％、Mo≦0.40％、1.0％≦Cu≦3.0％、0.06％≦N≦0.20％を含有し、残部がFeおよび不可避不純物からなり、
式1に示すδフェライト量(％)が6.0以下であり、且つ、NとSの含有量が式２及び式３に示す関係を満足するオーステナイト系ステンレス鋼である。
That is, in the present invention, by weight%, C ≦ 0.10%, Si ≦ 1.0%, P ≦ 0.10%, S ≦ 0.010%, 3.0% ≦ Mn ≦ 7.0%, 2.0% ≦ Ni ≦ 5.0%, 16.0% ≦ Cr ≦ 20.0%, Mo ≦ 0.40%, 1.0% ≦ Cu ≦ 3.0%, 0.06% ≦ N ≦ 0.20%, the balance consists of Fe and inevitable impurities,
This is an austenitic stainless steel in which the amount (%) of δ ferrite shown in Formula 1 is 6.0 or less, and the contents of N and S satisfy the relationships shown in Formula 2 and Formula 3.
δフェライト量(％)
＝−9.0−29.2C＋2.5Si−0.04Mn−1.9Ni＋1.7Cr＋5.5Mo−1.2Cu−53.5N…式１
％N≦0.11％の時、S（ppm）≦−833.3％N＋116.7 …式2
％N＞0.11％の時、S（ppm）≦25 …式3
δ Ferrite content (%)
= -9.0-29.2C + 2.5Si-0.04Mn-1.9Ni + 1.7Cr + 5.5Mo-1.2Cu-53.5N ... Formula 1
When% N ≦ 0.11%, S (ppm) ≦ −833.3% N + 116.7… Formula 2
When% N> 0.11%, S (ppm) ≤ 25 ... Formula 3
以上のように、Ni量が低減された上記成分範囲において、δフェライト量(％)が6.0以下であるから、熱間圧延時にオーステナイトとδフェライトとの間の変形能差による耳割れを解消することが出来、且つ、NとSとの関係が式2及び式3に示す範囲内であれば、Sによる熱間圧延割れ感受性を低下させることが出来、これによって本発明のオーステナイト系ステンレス鋼は、SUS304と同等の製造性と特性を有しており、SUS304と類似した用途に使用できる安価なステンレス鋼を供給できるようになった。 As described above, since the amount of δ ferrite (%) is 6.0 or less in the above-described component range in which the amount of Ni is reduced, ear cracks due to the deformability difference between austenite and δ ferrite are eliminated during hot rolling. If the relationship between N and S is within the range shown in Formula 2 and Formula 3, the hot-rolling cracking susceptibility due to S can be reduced, whereby the austenitic stainless steel of the present invention is It has the same manufacturability and characteristics as SUS304, and it has become possible to supply inexpensive stainless steel that can be used for applications similar to SUS304.
まず、本発明における化学組成の限定理由について説明する。 First, the reason for limiting the chemical composition in the present invention will be described.
1）C≦0.10％：Cはオーステナイト形成元素であるが、過剰添加は、溶接熱影響部や熱間圧延巻取り後の熱間圧延コイルの熱でCr炭化物が粒界に析出し、粒界腐食感受性を高め、さらには粒界型の応力腐食割れも起こしやすくする。また、C添加は固溶強化となり、冷間加工性を低下させる。このため、上限を0.10％とする。なお、上述したようにオーステナイトの安定化のために、0.04％以上の添加が好ましい。 1) C ≦ 0.10%: C is an austenite-forming element, but excessive addition causes Cr carbide to precipitate at the grain boundaries due to the heat of the heat affected zone and the hot rolled coil after hot rolling. Increases corrosion susceptibility and also easily causes intergranular stress corrosion cracking. Moreover, C addition becomes a solid solution strengthening and reduces cold workability. For this reason, the upper limit is made 0.10%. As described above, 0.04% or more is preferable for stabilizing austenite.
2）Si≦1.0％：Siは溶解時の脱酸剤の役割をすると同時に耐食性を増加させる効果もある。しかし、フェライト生成元素のため、オーステナイト組織を得るためには不利である。また、1％を超える添加は熱間加工性を害するだけでなくσ相生成を助長するので好ましくない。このため、その上限を1.0％とした。 2) Si ≦ 1.0%: Si acts as a deoxidizer when dissolved, and at the same time has the effect of increasing corrosion resistance. However, since it is a ferrite-forming element, it is disadvantageous for obtaining an austenite structure. Addition exceeding 1% is not preferable because it not only impairs hot workability but also promotes σ phase formation. For this reason, the upper limit was made 1.0%.
3）P≦0.10％：Pは耐食性や熱間加工性を劣化させるため、その上限を0.10％とした。 3) P ≦ 0.10%: Since P deteriorates corrosion resistance and hot workability, the upper limit was made 0.10%.
4）S≦0.010％：Sは、介在物を増加させ、また耐発銹性を低下させる。また、熱間加工性を著しく低下させる。Sの含有量は前記式２，３にて規定される量であり、N含有量が％N≦0.11％の範囲である場合、S含有量はS（ppm）≦−833.3％N＋116.7(式2)で示され、N含有量が％N＞0.11％の場合、S含有量はS（ppm）≦25(式3)で示される。N含有量が0.06％の場合、S含有量の上限は67ppmである。従って上限は0.010％とした。 4) S ≦ 0.010%: S increases inclusions and reduces rust resistance. In addition, hot workability is significantly reduced. The S content is the amount defined by the above formulas 2 and 3, and when the N content is in the range of% N ≦ 0.11%, the S content is S (ppm) ≦ −833.3% N + 116.7 ( When the N content is represented by Formula 2) and% N> 0.11%, the S content is represented by S (ppm) ≦ 25 (Formula 3). When the N content is 0.06%, the upper limit of the S content is 67 ppm. Therefore, the upper limit was made 0.010%.
5）3.0％≦Mn≦7.0％：Mnはオーステナイト形成元素あり、加工誘起マルテンサイト（α’）の生成を抑制し、加工硬化を低くすることができるため、冷間圧延性の向上に有利となる。この効果を得るためには3.0％以上が必要であるが、Mnの過剰添加は耐食性を低下させる恐れがあるため、上限を7.0％とした。 5) 3.0% ≤ Mn ≤ 7.0%: Mn is an austenite-forming element that suppresses the formation of work-induced martensite (α ') and lowers work hardening, which is advantageous for improving cold rolling properties. Become. In order to obtain this effect, 3.0% or more is necessary. However, excessive addition of Mn may reduce corrosion resistance, so the upper limit was made 7.0%.
6）2.0％≦Ni≦5.0％：Niはオーステナイト形成元素であり、オーステナイト組織の安定化や、良好な熱間加工性や冷間加工性を得るためには、Mn添加ステンレス鋼においても必要とされる元素であり、2.0％以上は添加する必要がある。しかし、Ni価格は高価であるため、その上限を5.0％、下限を2.0％とした。 6) 2.0% ≤ Ni ≤ 5.0%: Ni is an austenite-forming element and is necessary for Mn-added stainless steel to stabilize the austenite structure and to obtain good hot workability and cold workability. It is necessary to add 2.0% or more. However, since the Ni price is expensive, the upper limit is set to 5.0% and the lower limit is set to 2.0%.
7）16.0％≦Cr≦20.0％：Crはステンレス鋼の耐食性を高めるのにもっとも有効な元素のひとつであるが、そのためには13.0％以上の添加が必要である。しかし、SUS304と同等の耐食性を得るためには16.0％以上は必要であるが、20.0％を超える添加は、δフェライトの生成や熱間加工性の低下をもたらし好ましくない。よって、Cｒの上限を20.0％とした。 7) 16.0% ≦ Cr ≦ 20.0%: Cr is one of the most effective elements for enhancing the corrosion resistance of stainless steel, but for that purpose, addition of 13.0% or more is necessary. However, in order to obtain the same corrosion resistance as SUS304, 16.0% or more is necessary, but addition exceeding 20.0% is not preferable because it produces δ ferrite and decreases hot workability. Therefore, the upper limit of Cr is set to 20.0%.
8）Mo≦0.40％：MoはCrと並んで、ステンレス鋼の耐食性を高めるのに有効な元素であるが、その添加はコストを大きくするため、上限を0.40％とした。 8) Mo ≦ 0.40%: Mo, along with Cr, is an effective element for enhancing the corrosion resistance of stainless steel, but its addition increases the cost, so the upper limit was made 0.40%.
9）1.0％≦Cu≦3.0％：Cuはオーステナイト形成元素として作用し、また、材料の軟質化に効果がある。このような効果を有効に発揮させるためには1.0％以上が必要である。しかし3.0％を超える添加は低融点のMn-Cu相やCu相を形成して熱間加工性を悪くするため、上限を3.0％とした。 9) 1.0% ≦ Cu ≦ 3.0%: Cu acts as an austenite forming element and is effective in softening the material. In order to exhibit such an effect effectively, 1.0% or more is necessary. However, addition over 3.0% forms a low melting point Mn-Cu phase or Cu phase and deteriorates hot workability, so the upper limit was made 3.0%.
10）0.06％≦N≦0.20％：NはCと同様にオーステナイト形成元素であり、オーステナイト組織の安定化に寄与し、さらに耐食性の向上に効果あるが、その効果を得るためには0.06％以上は必要である。しかし、Nは固溶強化能が大きいため、0.20％を超える添加は、著しい材料硬化をもたらす。したがって、上限0.20％、下限0.06％とした。 10) 0.06% ≤ N ≤ 0.20%: N is an austenite-forming element like C, and contributes to the stabilization of the austenite structure and is further effective in improving corrosion resistance. To obtain this effect, 0.06% or more Is necessary. However, since N has a high solid solution strengthening ability, addition over 0.20% results in significant material hardening. Therefore, the upper limit is 0.20% and the lower limit is 0.06%.
更に、この熱間加工性については、スラブのδフェライト量と相関があることが知られている。これは、高温領域でのオーステナイトとフェライトとの変形能差による割れが関係している。そこで、表１に示す成分範囲で溶解・鋳造した９０成分(＝90種類)のインゴットのδフェライト量を測定し、該インゴットを1200℃×60分の加熱後、4段圧延機で熱間圧延したときの、熱間割れ状況を調査した。そして、成分との関係を解析し、式1で表されるδフェライト量（％）の関係式を得た。オーステナイト形成元素はδフェライト量を低減し、フェライト形成元素はδフェライト量を増加させることが分かった。また、Mnのオーステナイト形成能力は非常に小さいこともわかった。 Further, it is known that this hot workability has a correlation with the amount of δ ferrite of the slab. This is related to cracking due to a difference in deformability between austenite and ferrite in a high temperature region. Therefore, the amount of δ ferrite of 90 components (= 90 types) ingots melted and cast in the component ranges shown in Table 1 was measured, and the ingot was heated at 1200 ° C. for 60 minutes and then hot-rolled with a four-high mill. We investigated the hot cracking situation. Then, the relationship with the components was analyzed, and the relational expression of the amount of δ ferrite (%) represented by Expression 1 was obtained. It has been found that austenite forming elements reduce the amount of δ ferrite and ferrite forming elements increase the amount of δ ferrite. It was also found that the ability of Mn to form austenite is very small.
δフェライト量（％）
＝−9.0−29.2C＋2.5Si−0.04Mn−1.9Ni＋1.7Cr＋5.5Mo−1.2Cu−53.5N…式1
そして、インゴットで実測したδフェライト量と式1のδフェライト量および熱間圧延時の熱間割れの発生状況を図1に示す。式1から算出されるδフェライト量が6.0％を越えると熱間割れの発生確率が高くなることが分かる。また、Cu含有量が上限の3.0％を超えるとδフェライト量に関係なく熱間割れが発生する。
δ Ferrite content (%)
= -9.0-29.2C + 2.5Si-0.04Mn-1.9Ni + 1.7Cr + 5.5Mo-1.2Cu-53.5N ... Formula 1
FIG. 1 shows the amount of δ ferrite actually measured with an ingot, the amount of δ ferrite of Formula 1, and the occurrence of hot cracking during hot rolling. It can be seen that when the amount of δ ferrite calculated from Equation 1 exceeds 6.0%, the probability of hot cracking increases. If the Cu content exceeds the upper limit of 3.0%, hot cracking occurs regardless of the amount of δ ferrite.
また、本発明では、熱間加工性とS含有量の関係は、N含有量の影響を受けることが確認された。図2に熱間割れ発生の有無とN及びS含有量の関係を示す。N≦0.11％では熱間割れ(耳割れ)が発生しないSの上限値はNの低下とともに高くなることがわかった。すなわち、熱間割れが発生しないSの範囲はN含有量に応じて式2および式3の関係のあることが分かった。つまり、N％が0.11％以下の範囲では、Ｓは式２に、Ｎ％が0.11％を越える部分ではSは式３に従う。 Further, in the present invention, it was confirmed that the relationship between hot workability and S content is affected by the N content. Fig. 2 shows the relationship between the presence of hot cracking and the N and S contents. It was found that when N ≦ 0.11%, the upper limit of S at which hot cracking (ear cracking) does not occur increases as N decreases. That is, it was found that the range of S in which hot cracking does not occur has the relationship of Formula 2 and Formula 3 depending on the N content. That is, when N% is 0.11% or less, S follows Formula 2, and when N% exceeds 0.11%, S follows Formula 3.
％N≦0.11の時、S（ppm）≦−833.3％N+116.7 …式２
％N＞0.11の時、S（ppm）≦25 …式３
ＮとＳの間にこのような関係が生じる機構は、以下のように考えられる。Ｎの低下によってδフェライト量は増加するが、同時にオーステナイト中のＮ固溶量も減少し、オーステナイトの高温強度が低下する。一方、δフェライト中にはＮが殆ど固溶しないため、Ｎ量の増減にかかわらず高温強度の変化は小さい。このため、熱間圧延温度域において、オーステナイトとδフェライトの変形能差は小さくなるので、Ｎ量の低下によって、熱間割れ感受性は低くなると考えられる。
When% N ≦ 0.11, S (ppm) ≦ −833.3% N + 116.7… Formula 2
When% N> 0.11, S (ppm) ≦ 25 (3)
The mechanism by which such a relationship occurs between N and S is considered as follows. Although the amount of δ ferrite increases as N decreases, the amount of N solid solution in austenite also decreases and the high temperature strength of austenite decreases. On the other hand, since N hardly dissolves in δ ferrite, the change in high-temperature strength is small regardless of the increase or decrease in the amount of N. For this reason, in the hot rolling temperature range, the difference in deformability between austenite and δ ferrite becomes small, so it is considered that the hot cracking susceptibility becomes low due to the decrease in the N content.
一方、一般的にＳの増加は熱間割れ感受性を高くすることが知られている。これはＳが粒界に偏析し、高温での粒界を脆弱にするためである。低Ｎであれば、それによる熱間割れ感受性の低下分と、Ｓ増による熱間割れ感受性の増加分が相殺されると考えられる。そのため、低Ｎほど、より多くＳが含有しても、熱間割れに至らないと考えられる。 On the other hand, it is generally known that an increase in S increases the hot cracking sensitivity. This is because S segregates at the grain boundaries and weakens the grain boundaries at high temperatures. If it is low N, it is considered that the decrease in hot cracking sensitivity due to this and the increase in hot cracking sensitivity due to an increase in S are offset. For this reason, it is considered that hot cracking does not occur even if the content of S increases as the content of N decreases.
［実施例１］
高周波溶解炉にて、３８ｍｍ×９０ｍｍ×１５０ｍｍのインゴットを製作し、表面を機械研削した後、電気炉内で１２００℃×６０分の加熱をし、４段圧延機で３ｍｍ厚まで熱間圧延した。得られた熱間圧延板を１１００℃×６分で焼鈍し、硝ふっ酸浸漬で、スケールを除去したのち、４段圧延機で0.８ｍｍまで冷間圧延した。得られた冷延板を１１００℃×２分で焼鈍し、硝ふっ酸浸漬でスケールを除去した。
[Example 1]
An ingot of 38 mm x 90 mm x 150 mm was manufactured in a high-frequency melting furnace, the surface was mechanically ground, heated in an electric furnace at 1200 ° C for 60 minutes, and hot-rolled to a thickness of 3 mm with a four-high mill. . The obtained hot-rolled sheet was annealed at 1100 ° C. for 6 minutes, and after removing the scale by immersion in nitric hydrofluoric acid, it was cold-rolled to 0.8 mm with a four-high rolling mill. The obtained cold-rolled sheet was annealed at 1100 ° C. for 2 minutes, and the scale was removed by immersion in nitric hydrofluoric acid.
表２に成分、製造結果および耐食性の指標である孔食電位を示す。比較鋼７はSUS304に相当する。開発鋼１〜９は、δフェライト量が6.0％以下であり、熱間圧延時に割れを生じることなく、SUS304と同等の孔食電位が得られた。一方、比較鋼１および比較鋼２は、Ｃｕを3.0％を越えて含んでいるため、熱間圧延時に熱間割れが発生した。また、比較鋼３〜５はδフェライト量が６.０％を超えているため、熱間圧延時に熱間割れが発生した。そして、比較鋼１および３はMｎが上限を超えており、比較鋼６はさらにＣｒとＮが下限を下回っているため、孔食電位が低くなった。 Table 2 shows the components, production results, and pitting potential as an index of corrosion resistance. Comparative steel 7 corresponds to SUS304. The developed steels 1 to 9 had a δ ferrite amount of 6.0% or less, and a pitting potential equivalent to that of SUS304 was obtained without cracking during hot rolling. On the other hand, since comparative steel 1 and comparative steel 2 contain more than 3.0% of Cu, hot cracking occurred during hot rolling. In Comparative Steels 3 to 5, since the amount of δ ferrite exceeded 6.0%, hot cracking occurred during hot rolling. And since the comparative steels 1 and 3 had Mn exceeding the upper limit and the comparative steel 6 further had Cr and N below the lower limit, the pitting corrosion potential was low.
また、図３に開発鋼３〜６，９および比較鋼７の冷間圧延における硬さ変化を示す。いずれの開発鋼も、比較鋼７と同等もしくは加工硬化が小さかった。 FIG. 3 shows changes in hardness of the developed steels 3 to 6, 9 and the comparative steel 7 during cold rolling. All the developed steels were the same as the comparative steel 7 or the work hardening was small.
［実施例２］
実機製造設備にて、電気炉で溶解し、AOD炉で精錬し、連続鋳造機で表３の成分を有するスラブを製造した。このスラブを熱間圧延−焼鈍酸洗−冷間圧延−焼鈍酸洗−調質圧延を経て、０.８ｍｍの冷延板を得た。これら鋼帯についての評価結果を表３および表４に示す。
[Example 2]
In an actual machine manufacturing facility, the slab was melted in an electric furnace and refined in an AOD furnace, and a slab having the components shown in Table 3 was produced in a continuous casting machine. This slab was subjected to hot rolling-annealing pickling-cold rolling-annealing pickling-temper rolling to obtain a 0.8 mm cold-rolled sheet. The evaluation results for these steel strips are shown in Tables 3 and 4.
比較鋼12はSUS304である。いずれもδフェライト量は６.０％以下であったが、ＳとＮで関係式(式２、式３)を満たさない比較鋼８〜11では熱間割れが発生した。そして、開発鋼10，12，14〜16および比較鋼12では、ほぼ同等の耐食性があった。 The comparative steel 12 is SUS304. In either case, the amount of δ ferrite was 6.0% or less, but hot cracking occurred in comparative steels 8 to 11 in which S and N did not satisfy the relational expressions (Formula 2 and Formula 3). The developed steels 10, 12, 14 to 16 and the comparative steel 12 had almost the same corrosion resistance.
また、図４に開発鋼12，15，16および比較鋼12の冷間圧下率に対する硬さ変化を示す。いずれの開発鋼も比較鋼12よりも加工硬化は小さかった。そのため、冷間圧延時にはパス増せず、生産性を低下させることなく圧延を完了することできた。 FIG. 4 shows the change in hardness of the developed steels 12, 15, 16 and the comparative steel 12 with respect to the cold rolling reduction. All developed steels had less work hardening than comparative steel 12. Therefore, the number of passes was not increased during cold rolling, and rolling could be completed without reducing productivity.
Claims (1)
式1に示すδフェライト量(％)が6.0以下であり、且つ、NとSの含有量が式２及び式３に示す関係を満足することを特徴とするオーステナイト系ステンレス鋼。
δフェライト量(％)
＝−9.0−29.2C＋2.5Si−0.04Mn−1.9Ni＋1.7Cr＋5.5Mo−1.2Cu−53.5N…式１
％N≦0.11％の時、S（ppm）≦−833.3％N＋116.7 …式2
％N＞0.11％の時、S（ppm）≦25 …式3 % By weight, C ≦ 0.10%, Si ≦ 1.0%, P ≦ 0.10%, S ≦ 0.010%, 3.0% ≦ Mn ≦ 7.0%, 2.0% ≦ Ni ≦ 5.0%, 16.0% ≦ Cr ≦ 20.0%, Mo ≦ Containing 0.40%, 1.0% ≦ Cu ≦ 3.0%, 0.06% ≦ N ≦ 0.20%, the balance consisting of Fe and inevitable impurities,
An austenitic stainless steel characterized in that the amount (%) of δ ferrite shown in Formula 1 is 6.0 or less, and the contents of N and S satisfy the relationships shown in Formula 2 and Formula 3.
δ Ferrite content (%)
= -9.0-29.2C + 2.5Si-0.04Mn-1.9Ni + 1.7Cr + 5.5Mo-1.2Cu-53.5N ... Formula 1
When% N ≦ 0.11%, S (ppm) ≦ −833.3% N + 116.7… Formula 2
When% N> 0.11%, S (ppm) ≤ 25 ... Formula 3
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| JP2009024251A (en) * | 2007-07-18 | 2009-02-05 | Samkyung Trading Corp | Low-nickel austenitic stainless steel and method for producing same |
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