JP5863770B2 - Austenitic cast stainless steel - Google Patents

Austenitic cast stainless steel Download PDF

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JP5863770B2
JP5863770B2 JP2013507281A JP2013507281A JP5863770B2 JP 5863770 B2 JP5863770 B2 JP 5863770B2 JP 2013507281 A JP2013507281 A JP 2013507281A JP 2013507281 A JP2013507281 A JP 2013507281A JP 5863770 B2 JP5863770 B2 JP 5863770B2
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JPWO2012132679A1 (en
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坂本　伸之
伸之 坂本
実 日根野
実 日根野
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/20—Measures not previously mentioned for influencing the grain structure or texture; Selection of compositions therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D30/00—Cooling castings, not restricted to casting processes covered by a single main group
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Description

本発明は、オーステナイト系ステンレス鋳鋼に関する。   The present invention relates to an austenitic stainless cast steel.

オーステナイト系ステンレス鋳鋼は耐食性、強度、溶接性等に特に優れているため、化学プラントや発電プラントの配管やバルブ等において広く使用されている。オーステナイト系ステンレス鋳鋼は、例えば冶金学的には約１０〜２０％のα相と約９０〜８０％のγ相（オーステナイト相）の二相から形成されている。   Since austenitic stainless cast steel is particularly excellent in corrosion resistance, strength, weldability and the like, it is widely used in piping and valves of chemical plants and power plants. Austenitic stainless cast steel is formed, for example, from the metallurgical viewpoint of two phases of about 10 to 20% α phase and about 90 to 80% γ phase (austenite phase).

オーステナイト系ステンレス鋼の鋳鋼品として、ＣＦ８Ｃが公知である。例えば、ＣＦ８Ｃオーステナイト系ステンレス鋼鋳鋼品は、最大で０．０８質量％のＣ（炭素）、最大で２．０質量％のＳｉ（ケイ素）、最大で１．５質量％のＭｎ（マンガン）、１８．０〜２１．０質量％のＣｒ（クロム）、９．０〜１２．０質量％のＮｉ（ニッケル）、最大で１．０質量％のＮｂ（ニオブ）、を含んでいる。   CF8C is known as a cast steel product of austenitic stainless steel. For example, a CF8C austenitic stainless steel cast product has a maximum of 0.08 mass% C (carbon), a maximum of 2.0 mass% Si (silicon), a maximum of 1.5 mass% Mn (manganese), 18.0 to 21.0 mass% Cr (chromium), 9.0 to 12.0 mass% Ni (nickel), and 1.0 mass% Nb (niobium) at the maximum.

ＣＦ８Ｃは約１２．０％のフェライト相を含有する。フェライト相は、例えば公知のフェライトスコープでオーステナイト系ステンレス鋼中のフェライト含有量を測定する、或いは、成分元素に基づくシェフラー状態図から算出でき、体積率（パーセント（％））で表示する。   CF8C contains about 12.0% ferrite phase. For example, the ferrite phase can be calculated from a Schaeffler phase diagram based on the constituent elements by measuring the ferrite content in the austenitic stainless steel with a known ferrite scope, and is displayed in volume ratio (percent (%)).

当該フェライト相は、溶接割れの防止、応力腐食割れの軽減に有効であるとされる。しかし、フェライト相の含有量が多くなると、例えばＣＦ８Ｃを長期間高温に暴露した場合、当該フェライト相が鉄とクロムの化合物であるシグマ相（σ相）に変態して脆化する虞がある。   The ferrite phase is said to be effective in preventing weld cracking and reducing stress corrosion cracking. However, when the content of the ferrite phase increases, for example, when CF8C is exposed to a high temperature for a long period of time, the ferrite phase may be transformed into a sigma phase (σ phase) that is a compound of iron and chromium and embrittled.

特許文献１には、ＣＦ８Ｃを改変した合金であるＣＦ８Ｃ−Ｐｌｕｓが開示されており、当該ＣＦ８Ｃ−Ｐｌｕｓはフェライト相を含まないことが記載してある。特許文献１では、ＣＦ８Ｃ−Ｐｌｕｓは、０．０５〜０．１５質量％のＣ、０．２〜１．０質量％のＳｉ、０．５〜１０．０質量％のＭｎ、１８．０〜２５．０質量％のＣｒ、１０．０〜１５．０質量％のＮｉ、０．１〜１．５質量％のＮｂ、０．０５〜０．５質量％のＮ、を含むとされている。   Patent Document 1 discloses CF8C-Plus, which is an alloy obtained by modifying CF8C, and describes that the CF8C-Plus does not contain a ferrite phase. In patent document 1, CF8C-Plus is 0.05-0.15 mass% C, 0.2-1.0 mass% Si, 0.5-10.0 mass% Mn, 18.0 25.0 mass% Cr, 10.0-15.0 mass% Ni, 0.1-1.5 mass% Nb, 0.05-0.5 mass% N .

ＣＦ８Ｃ−Ｐｌｕｓにフェライト相が存在しないことは、材料から作製した構成部品の寿命の間、材料の鋳造時の特性を維持するために重要であるとされている。   The absence of a ferrite phase in CF8C-Plus is considered important to maintain the properties of the material during casting for the life of the component made from the material.

特表２００９−５４５６７５号公報Special table 2009-545675

ＣＦ８Ｃは使用環境下で長期間高温に暴露した場合、シグマ相が析出して時効脆化を生じ、時効延性が不十分となる虞があった。また、特許文献１に記載のＣＦ８Ｃ−Ｐｌｕｓにおいても、耐酸化性について更なる改善が求められていた。   When CF8C is exposed to a high temperature for a long period of time in a use environment, the sigma phase is precipitated to cause aging embrittlement and the aging ductility may be insufficient. Further, in CF8C-Plus described in Patent Document 1, further improvement in oxidation resistance has been demanded.

従って、本発明の目的は、時効延性および耐酸化性に優れたオーステナイト系ステンレス鋳鋼を提供することにある。   Accordingly, an object of the present invention is to provide an austenitic stainless cast steel excellent in aging ductility and oxidation resistance.

上記目的を達成するため、以下の［１］〜［２］に示す発明を提供する。
［１］ フェライト相の体積率が０．１〜５．０％であり、
Ｃ：０．０１〜０．１０質量％、Ｓｉ：０．６〜１．０質量％、Ｍｎ：２．０〜２．８質量％、Ｎ：０．１〜０．４質量％、Ｃｒ：１８．０〜２４．０質量％、Ｎｉ：８．０〜１５．０質量％、Ｎｂ：０．２〜０．７質量％、を含有し、
残部がＦｅおよび不可避不純物であるオーステナイト系ステンレス鋳鋼。
［２］ 上記［１］に記載のオーステナイト系ステンレス鋳鋼を用いて形成されたバルブ。 In order to achieve the above object, the following inventions [1] to [2] are provided.
[1] The volume fraction of the ferrite phase is 0.1 to 5.0%,
C: 0.01-0.10 mass%, Si: 0.6-1.0 mass%, Mn: 2.0-2.8 mass%, N: 0.1-0.4 mass%, Cr: 18.0 to 24.0 mass%, Ni: 8.0 to 15.0 mass%, Nb: 0.2 to 0.7 mass%,
An austenitic stainless cast steel with the balance being Fe and inevitable impurities.
[2] A valve formed using the austenitic stainless cast steel according to [1] .

本発明のオーステナイト系ステンレス鋳鋼は、例えば後述の実施例にて示したように、時効延性・引張強度・耐酸化性について優れたものとなる。特に、時効延性については、本発明の実施例は比較例の２．４倍程度となっていた。同様に、耐酸化性については、本発明の実施例は比較例の９．５倍程度に改善されたものと認められた。   The austenitic stainless cast steel of the present invention is excellent in aging ductility, tensile strength, and oxidation resistance, for example, as shown in Examples described later. In particular, the aging ductility of the examples of the present invention was about 2.4 times that of the comparative examples. Similarly, regarding the oxidation resistance, it was recognized that the example of the present invention was improved to about 9.5 times the comparative example.

当該オーステナイト系ステンレス鋳鋼がこのような優れた特性を有する理由として、フェライト相の体積率が０．１〜５．０％となっている点、含有成分であるＣ、Ｓｉ、Ｍｎ、Ｃｒ、Ｎｉ、Ｎｂ、Ｎの含有量が重要であると考えられる。各成分について詳述する。   The reason why the austenitic stainless cast steel has such excellent characteristics is that the volume fraction of the ferrite phase is 0.1 to 5.0%, and the contained components C, Si, Mn, Cr, Ni , Nb, N content is considered important. Each component will be described in detail.

フェライト相の体積率を０．１〜５．０％とすることで、長期間高温に暴露した場合であっても、シグマ相の析出量を少なくすることができる。当該シグマ相の析出量が少なくなることで、オーステナイト系ステンレス鋳鋼が脆化し難くなり、時効延性に優れたオーステナイト系ステンレス鋳鋼となる。   By setting the volume fraction of the ferrite phase to 0.1 to 5.0%, the amount of sigma phase deposited can be reduced even when exposed to high temperatures for a long period of time. By reducing the precipitation amount of the sigma phase, the austenitic stainless cast steel becomes difficult to become brittle, and an austenitic stainless cast steel excellent in aging ductility is obtained.

Ｃは、融点を低下させ、溶湯の流動性、即ち鋳造性を改善する作用がある。また、Ｃは耐食性の観点から低いほど好ましく、多量に添加されると母材の耐食性を低下させる。これらを踏まえ、本発明では高温延性を改善するため、Ｃの添加量を０．０１〜０．１０質量％としている。   C has the effect of lowering the melting point and improving the fluidity of the molten metal, that is, the castability. Further, C is preferably as low as possible from the viewpoint of corrosion resistance, and when added in a large amount, the corrosion resistance of the base material is lowered. Based on these, in the present invention, in order to improve high temperature ductility, the amount of C added is set to 0.01 to 0.10% by mass.

Ｓｉは、溶湯の脱酸剤および流動性改善、耐酸化性、溶接性の改善に有効な元素である。しかし、過剰に加えるとオーステナイト組織が不安定になり、鋳造性の劣化を招きまた、加工性、溶接性の阻害や溶接割れを助長する。そのため、本発明ではＳｉの添加量を０．６〜１．０質量％としている。   Si is an element effective for improving the deoxidizer and flowability, oxidation resistance, and weldability of the molten metal. However, if added excessively, the austenite structure becomes unstable, which causes deterioration of castability, and promotes hindrance to workability and weldability and weld cracking. Therefore, in the present invention, the addition amount of Si is set to 0.6 to 1.0 mass%.

Ｍｎは、溶湯の脱酸剤として有効であり、鋳造時の湯流れ性を向上させて生産性を改善する。さらに、溶接割れの低減に有効である。過度の添加は耐酸化性を損なうことから、本発明ではＭｎの添加量を２．０〜２．８質量％としている。Ｍｎがこの範囲であれば、後述の実施例で示したように、耐酸化性に優れたオーステナイト系ステンレス鋳鋼を得ることができる。   Mn is effective as a deoxidizer for molten metal, and improves the flowability during casting to improve productivity. Furthermore, it is effective in reducing weld cracking. Since excessive addition impairs oxidation resistance, the amount of Mn added is set to 2.0 to 2.8% by mass in the present invention. If Mn is in this range, as shown in the examples described later, austenitic stainless cast steel having excellent oxidation resistance can be obtained.

Ｎは、高温強度および耐熱疲労性を改善する元素であり、強力なオーステナイト生成元素であり、オーステナイト基地を安定にする。また、結晶粒微細化に有効な元素である。この結晶粒微細化により、構造物として重要な材料の延性の確保が可能になり、また、オーステナイト系ステンレス鋳鋼に特有な被削性が悪いという欠点を改善できる。特に、部品を連結するために穿孔加工を施される部材では、穿孔加工性が良好となる。Ｎを多量に添加すると、脆化を促進する一方、有効なＣｒ量が減少し耐酸化性を劣化させる。そのため、本発明ではＮの添加量を０．１〜０．４質量％としている。   N is an element that improves high-temperature strength and heat fatigue resistance, is a strong austenite-forming element, and stabilizes the austenite base. It is also an effective element for grain refinement. This refinement of crystal grains makes it possible to ensure the ductility of materials that are important as structures, and to improve the disadvantage of poor machinability that is characteristic of austenitic cast stainless steel. In particular, in a member that is subjected to a drilling process for connecting parts, the drilling processability is improved. When a large amount of N is added, embrittlement is promoted, while an effective amount of Cr is reduced and oxidation resistance is deteriorated. Therefore, in this invention, the addition amount of N is 0.1-0.4 mass%.

Ｃｒは、耐酸化性を改善し、フェライト組織を安定にする元素であるが、その効果を確実にするため１８．０質量％以上とする。一方、多量の添加は、高温使用過程で、Ｃｒ炭化物の過剰析出による鋼の時効延性の低下をきたすので、２４．０質量％を上限とする。   Cr is an element that improves the oxidation resistance and stabilizes the ferrite structure, but is made 18.0% by mass or more in order to ensure the effect. On the other hand, the addition of a large amount causes a decrease in the aging ductility of the steel due to excessive precipitation of Cr carbide in the course of high temperature use, so the upper limit is 24.0% by mass.

Ｎｉは、安定なオーステナイト基地を形成し、オーステナイト相を安定化させ、鋼の高温強度、耐酸化性を高める。良好な鋳造性・耐食性及び溶接性を考慮して、本発明ではＮｉの添加量を８．０〜１５．０質量％としている。   Ni forms a stable austenite base, stabilizes the austenite phase, and improves the high temperature strength and oxidation resistance of the steel. In consideration of good castability / corrosion resistance and weldability, in the present invention, the addition amount of Ni is set to 8.0 to 15.0 mass%.

Ｎｂは、Ｃと結合して微細な炭化物を形成し、高温強度を改善する。また、Ｃｒ炭化物の生成を抑制することによって、耐酸化性を向上させる。これらの効果を有効に発揮させるためには、含有量は０.２％以上必要である。しかし、多量に添加すると、高温割れ感受性を著しく高め、内部品質を悪化させることから、本発明ではＮｂの添加量を０．２〜０．７質量％としている。   Nb combines with C to form fine carbides and improves high temperature strength. Moreover, oxidation resistance is improved by suppressing the production | generation of Cr carbide | carbonized_material. In order to exhibit these effects effectively, the content must be 0.2% or more. However, when added in a large amount, the hot cracking sensitivity is remarkably increased and the internal quality is deteriorated. Therefore, in the present invention, the amount of Nb added is set to 0.2 to 0.7% by mass.

また、本発明のオーステナイト系ステンレス鋳鋼は、１１５０〜１３５０℃の温度範囲から、３０℃/分以上の冷却温度で、６００〜８００℃の温度範囲まで冷却することによって製造することができる。上記条件で本発明のオーステナイト系ステンレス鋳鋼を製造することで、鋳放しでも優れた強度特性を有するため、固溶化熱処理を省略することができる。
製造されたオーステナイト系ステンレス鋳鋼は、例えば、化学プラントや発電プラントの配管やバルブなどの材料として使用される。The austenitic stainless cast steel of the present invention can be produced by cooling from a temperature range of 1150 to 1350 ° C. to a temperature range of 600 to 800 ° C. at a cooling temperature of 30 ° C./min or more. By producing the austenitic stainless cast steel of the present invention under the above-mentioned conditions, since it has excellent strength characteristics even as cast, the solution heat treatment can be omitted.
The produced austenitic stainless cast steel is used, for example, as a material for piping and valves of chemical plants and power plants.

オーステナイト系ステンレス鋳鋼において、耐酸化性（ｍｍ／年）を調べた結果を示すグラフである。It is a graph which shows the result of having investigated oxidation resistance (mm / year) in austenitic stainless cast steel.

以下、本発明の実施形態を図面に基づいて説明する。
本発明のオーステナイト系ステンレス鋳鋼は、フェライト相の体積率が０．１〜５．０％、好ましくは０．５〜３．０％となるように構成される。本発明のオーステナイト系ステンレス鋳鋼は、成分として、Ｃ、Ｓｉ、Ｍｎ、Ｃｒ、Ｎｉ、Ｎｂ、Ｎなどを含有する。
Ｃは０．０１〜０．１０質量％、好ましくは０．０２〜０．０４質量％、
Ｓｉは０．６〜１．０質量％、好ましくは０．７〜０．９質量％、
Ｍｎは２．０〜２．８質量％、好ましくは２．２〜２．４質量％、
Ｎ：０．１〜０．４質量％、好ましくは０．１５〜０．２５質量％、
Ｃｒ：１８．０〜２４．０質量％、好ましくは１９．５〜２１．５質量％、
Ｎｉ：８．０〜１５．０質量％、好ましくは１０．５〜１２．５質量％、
Ｎｂ：０．２〜０．７質量％、好ましくは０．２〜０．４質量％、の含有量とする。
本発明のオーステナイト系ステンレス鋳鋼、および、参考としてＣＦ８ＣおよびＣＦ８Ｃ−Ｐｌｕｓにおける上記成分の組成（質量％）の範囲を表１に示す。Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The austenitic stainless cast steel of the present invention is configured so that the volume fraction of the ferrite phase is 0.1 to 5.0%, preferably 0.5 to 3.0%. The austenitic stainless cast steel of the present invention contains C, Si, Mn, Cr, Ni, Nb, N and the like as components.
C is 0.01 to 0.10% by mass, preferably 0.02 to 0.04% by mass,
Si is 0.6 to 1.0 mass%, preferably 0.7 to 0.9 mass%,
Mn is 2.0 to 2.8% by mass, preferably 2.2 to 2.4% by mass,
N: 0.1 to 0.4% by mass, preferably 0.15 to 0.25% by mass,
Cr: 18.0 to 24.0 mass%, preferably 19.5 to 21.5 mass%,
Ni: 8.0 to 15.0% by mass, preferably 10.5 to 12.5% by mass,
Nb: 0.2 to 0.7 mass%, preferably 0.2 to 0.4 mass%.
Table 1 shows the range of the composition (mass%) of the above components in the austenitic stainless cast steel of the present invention and, as a reference, CF8C and CF8C-Plus.

Figure 0005863770
Figure 0005863770

本発明のオーステナイト系ステンレス鋳鋼においてフェライト相の体積率を０．１〜５．０％とすることで、長期間高温に暴露した場合であっても、シグマ相の析出量を少なくすることができる。よって、本発明のオーステナイト系ステンレス鋳鋼は脆化し難くなり、時効延性に優れる。
また、本発明のオーステナイト系ステンレス鋳鋼では、Ｍｎの含有量をＣＦ８Ｃより高めており、Ｃの含有量を低めに設定している。これにより、高温での強度・耐酸化性を向上させることができる。By setting the volume fraction of the ferrite phase to 0.1 to 5.0% in the austenitic stainless cast steel of the present invention, the amount of precipitation of the sigma phase can be reduced even when exposed to high temperatures for a long time. . Therefore, the austenitic stainless cast steel of the present invention is not easily embrittled and is excellent in aging ductility.
In the austenitic stainless cast steel of the present invention, the Mn content is set higher than that of CF8C, and the C content is set lower. Thereby, strength and oxidation resistance at high temperatures can be improved.

本発明のオーステナイト系ステンレス鋳鋼には、上述した組成以外にもＷ、Ｂ、Ａｌ、Ｍｏ、Ｃｏ、Ｔｉ、Ｚｒ、Ｃｕ，希土類元素（Ｌａ，Ｃｅ，Ｙ，Ｐｄ，Ｎｄ等）などを含ませることができ、残部はＦｅおよび不可避不純物である。   The austenitic stainless cast steel of the present invention contains W, B, Al, Mo, Co, Ti, Zr, Cu, rare earth elements (La, Ce, Y, Pd, Nd, etc.) and the like in addition to the above-described composition. The balance is Fe and inevitable impurities.

上記の金属成分を、溶解炉にて溶解し、１１５０〜１３５０℃の温度範囲から、３０℃/分以上の冷却温度で、６００〜８００℃の温度範囲まで冷却することで、本発明のオーステナイト系ステンレス鋳鋼を作製することができる。この条件で本発明のオーステナイト系ステンレス鋳鋼を製造することで、鋳放しでも優れた強度特性を有するため、固溶化熱処理を省略することができる。   The above-mentioned metal component is melted in a melting furnace and cooled to a temperature range of 600 to 800 ° C. at a cooling temperature of 1150 to 1350 ° C. or more at a cooling temperature of 30 ° C./min or more. Stainless cast steel can be produced. By producing the austenitic stainless cast steel of the present invention under these conditions, the solution has excellent strength characteristics even when cast, so that the solution heat treatment can be omitted.

製造されたオーステナイト系ステンレス鋳鋼は、例えば、化学プラントや発電プラントの配管やバルブなどにおいて使用される。   The produced austenitic stainless cast steel is used, for example, in piping and valves of chemical plants and power plants.

〔実施例１〕
本発明の実施例について説明する。
本発明のオーステナイト系ステンレス鋳鋼（実施例１−１〜１−６）、ＣＦ８Ｃ（比較例１−１〜１−５の主成分の組成（質量％）をそれぞれ表２，３に示す。[Example 1]
Examples of the present invention will be described.
The compositions (mass%) of the main components of the austenitic stainless cast steel of the present invention (Examples 1-1 to 1-6) and CF8C (Comparative Examples 1-1 to 1-5) are shown in Tables 2 and 3, respectively.

Figure 0005863770
Figure 0005863770

Figure 0005863770
Figure 0005863770

これら実施例および比較例について、時効延性（７００℃―６２０時間）、引張強度（９００℃）、０．２％耐力（９００℃）、耐酸化性（１０００℃）を調べ、さらに高温低サイクル疲労試験（両振三角波、歪速度０．１％／秒、７００℃、全ひずみ０．５％）を行なった。   For these examples and comparative examples, aging ductility (700 ° C.-620 hours), tensile strength (900 ° C.), 0.2% proof stress (900 ° C.), oxidation resistance (1000 ° C.) were examined, and high temperature low cycle fatigue The test (double oscillation triangle wave, strain rate 0.1% / second, 700 ° C., total strain 0.5%) was performed.

なお、実施例および比較例ともに鋳造は、通常の置注鋳造法によって行なった。熱処理については、実施例１，２はas cast（鋳放し）によって行い、その他の実施例および比較例はＳＨＴ（固溶化熱処理法）によって行った。時効延性、引張強度、０．２％耐力、耐酸化性を調べた結果を表４に示した。   In both the examples and the comparative examples, casting was performed by a conventional in-place casting method. Regarding heat treatment, Examples 1 and 2 were performed by as cast (as cast), and other Examples and Comparative Examples were performed by SHT (Solution Solution Heat Treatment). Table 4 shows the results of examining the aging ductility, tensile strength, 0.2% proof stress, and oxidation resistance.

Figure 0005863770
Figure 0005863770

この結果、時効延性については、実施例では２０．４％以上であるのに対して、比較例では１７．２％以下であった。
引張強度については、実施例では１１３〜１３４Ｍｐａであり、比較例では９３〜１２７Ｍｐａであった。
０．２％耐力については、実施例では８７〜９１Ｍｐａであり、比較例では７０〜８４Ｍｐａであった。
耐酸化性については、実施例では０．４８９ｍｍ／年 以下であり、比較例では１．２７８ｍｍ／年 以上であった。As a result, the aging ductility was 20.4% or more in the example, whereas it was 17.2% or less in the comparative example.
About the tensile strength, it was 113-134 Mpa in the Example, and it was 93-127 Mpa in the comparative example.
About 0.2% yield strength, it was 87-91 Mpa in the Example, and it was 70-84 Mpa in the comparative example.
The oxidation resistance was 0.489 mm / year or less in the example and 1.278 mm / year or more in the comparative example.

即ち、０．２％耐力については、実施例および比較例では顕著な差異は認められなかったものの、時効延性・引張強度・耐酸化性については、実施例のほうが優れていることが判明した。特に、時効延性については、実施例の平均値が２４．８％、比較例の平均値が１０．４％となっており、実施例は比較例の２．４倍程度となっていた。同様に、耐酸化性については、実施例の平均値が０．２９０ｍｍ／年、比較例の平均値が２．７７０ｍｍ／年となっており、実施例は比較例の９．５倍程度に改善されたものと認められた。
上述した結果は、本発明のオーステナイト系ステンレス鋳鋼のフェライト相の体積率が０．２％である場合であるが、フェライト相の体積率の下限を０．１％とした場合であっても同様の結果が得られるものと考えられる。That is, regarding the 0.2% proof stress, although no significant difference was observed between the examples and the comparative examples, it was found that the examples were superior in terms of aging ductility, tensile strength, and oxidation resistance. In particular, regarding the aging ductility, the average value of the example was 24.8%, the average value of the comparative example was 10.4%, and the example was about 2.4 times that of the comparative example. Similarly, regarding oxidation resistance, the average value of the example is 0.290 mm / year and the average value of the comparative example is 2.770 mm / year, and the example is improved to about 9.5 times the comparative example. It was recognized that
The above-described results are obtained when the volume fraction of the ferrite phase of the austenitic stainless cast steel of the present invention is 0.2%, but the same applies even when the lower limit of the volume fraction of the ferrite phase is 0.1%. It is thought that the result of is obtained.

〔実施例２〕
実施例１では、本発明のオーステナイト系ステンレス鋳鋼のフェライト相の体積率は０．２％であった（実施例１−１〜１−６）が、これに限らず、フェライトト相の体積率を１〜３％とした場合についても時効延性、引張強度、０．２％耐力、耐酸化性を調べた（実施例２−１〜２−４）。これらは実施例１と同様の条件で行なった。実施例２−１〜２−４の各成分を表５に示し、結果を表６に示した。[Example 2]
In Example 1, the volume fraction of the ferrite phase of the austenitic stainless cast steel of the present invention was 0.2% (Examples 1-1 to 1-6), but not limited thereto, the volume fraction of the ferrite phase. Also in the case of 1 to 3%, aging ductility, tensile strength, 0.2% proof stress, and oxidation resistance were examined (Examples 2-1 to 2-4). These were performed under the same conditions as in Example 1. Each component of Examples 2-1 to 2-4 is shown in Table 5, and the results are shown in Table 6.

Figure 0005863770
Figure 0005863770

Figure 0005863770
Figure 0005863770

この結果、実施例２−１〜２−４における時効延性の平均値は２４．６％、耐酸化性の平均値は０．１５９ｍｍ／年となっており、これらの値は実施例１と同様に比較例より優れていると認められた。本発明のオーステナイト系ステンレス鋳鋼のフェライト相の体積率の上限を５％とした場合であっても同様の結果が得られると考えられる。   As a result, the average value of aging ductility in Examples 2-1 to 2-4 was 24.6%, and the average value of oxidation resistance was 0.159 mm / year. These values were the same as in Example 1. It was recognized that it was superior to the comparative example. Even if the upper limit of the volume fraction of the ferrite phase of the austenitic stainless cast steel of the present invention is 5%, it is considered that the same result can be obtained.

〔実施例３〕
Ｍｎの含有量が約１．０〜４．５質量％であるオーステナイト系ステンレス鋳鋼において、耐酸化性（ｍｍ／年）を調べた。本発明のオーステナイト系ステンレス鋳鋼は、Ｍｎの含有量が２．２６質量％（実施例３−１）、２．３３質量％（実施例３−２）の態様について調べた。比較例のオーステナイト系ステンレス鋳鋼は、Ｍｎの含有量が１．０４質量％（比較例３−１）、１．１７質量％（比較例３−２）、１．８１質量％（比較例３−３）、４．３７質量％（比較例３−４）、４．４８質量％（比較例３−５）の態様について調べた。これら実施例および比較例において、それぞれの成分を表７に示した。結果を表８および図１に示した。Example 3
The oxidation resistance (mm / year) of austenitic stainless cast steel having a Mn content of about 1.0 to 4.5% by mass was examined. The austenitic stainless cast steel of the present invention was examined for an embodiment in which the Mn content was 2.26% by mass (Example 3-1) and 2.33% by mass (Example 3-2). The austenitic stainless cast steel of the comparative example has a Mn content of 1.04% by mass (Comparative Example 3-1), 1.17% by mass (Comparative Example 3-2), and 1.81% by mass (Comparative Example 3- 3) The aspect of 4.37 mass% (Comparative Example 3-4) and 4.48 mass% (Comparative Example 3-5) was examined. In these Examples and Comparative Examples, the respective components are shown in Table 7. The results are shown in Table 8 and FIG.

Figure 0005863770
Figure 0005863770

Figure 0005863770
Figure 0005863770

図１より、本発明のオーステナイト系ステンレス鋳鋼では、Ｍｎの含有量が２．０〜２．８質量％であれば、耐酸化性を１ｍｍ／年 以下に抑制できるものと認められた。   From FIG. 1, in the austenitic stainless cast steel of the present invention, it was recognized that the oxidation resistance could be suppressed to 1 mm / year or less if the Mn content was 2.0 to 2.8% by mass.

本発明は、オーステナイト系ステンレス鋳鋼の製造に利用できる。   The present invention can be used for producing austenitic cast stainless steel.

Claims (2)

フェライト相の体積率が０．１〜５．０％であり、
Ｃ：０．０１〜０．１０質量％、Ｓｉ：０．６〜１．０質量％、Ｍｎ：２．０〜２．８質量％、Ｎ：０．１〜０．４質量％、Ｃｒ：１８．０〜２４．０質量％、Ｎｉ：８．０〜１５．０質量％、Ｎｂ：０．２〜０．７質量％、を含有し、
残部がＦｅおよび不可避不純物であるオーステナイト系ステンレス鋳鋼。 The volume fraction of the ferrite phase is 0.1 to 5.0%,
C: 0.01-0.10 mass%, Si: 0.6-1.0 mass%, Mn: 2.0-2.8 mass%, N: 0.1-0.4 mass%, Cr: 18.0 to 24.0 mass%, Ni: 8.0 to 15.0 mass%, Nb: 0.2 to 0.7 mass%,
An austenitic stainless cast steel with the balance being Fe and inevitable impurities. 請求項１に記載のオーステナイト系ステンレス鋳鋼を用いて形成されたバルブ。 A valve formed using the austenitic stainless cast steel according to claim 1 .
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017171178A1 (en) * 2016-03-28 2017-10-05 엘지전자 주식회사 Stainless steel and pipe made thereof

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018117683A1 (en) * 2016-12-23 2018-06-28 주식회사 포스코 Austenitic stainless steel having excellent processability and surface characteristics, and manufacturing method therefor
KR102030162B1 (en) 2016-12-23 2019-11-08 주식회사 포스코 Austenitic stainless steel having excellent formability and surface properties and manufacturing method of the same
CN109454220A (en) * 2018-11-24 2019-03-12 共享铸钢有限公司 A kind of production method of austenitic stainless steel material steel-casting
CN110093561B (en) * 2019-05-13 2021-06-18 襄阳市立强机械有限公司 As-cast nonmagnetic austenitic stainless steel and preparation method thereof
JP6793866B1 (en) 2020-06-17 2020-12-02 株式会社クボタ Gas valve and propane gas flow control method
CN113699453B (en) * 2021-08-30 2023-03-10 上海海塔机械制造有限公司 Heat-resistant high-nitrogen steel and production method thereof

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5487627A (en) * 1977-12-23 1979-07-12 Kubota Ltd Stainless steel for extreme low temperature excellent in weld ability
JPS5547370A (en) * 1978-09-30 1980-04-03 Kubota Ltd Stainless cast steel for cryogenic temperature use
JPS6353244A (en) * 1986-08-25 1988-03-07 Aichi Steel Works Ltd Stainless steel excellent in strength and corrosion resistance and having small anisotropy and its production
JPS63169362A (en) * 1986-12-29 1988-07-13 Aichi Steel Works Ltd Nonmagnetic tool steel
JPH05311337A (en) * 1992-05-08 1993-11-22 Nippon Yakin Kogyo Co Ltd High ductility austenite-ferrite duplex heat resistant steel and its manufacture
JPH06336653A (en) * 1993-05-27 1994-12-06 Agency Of Ind Science & Technol Production of stainless cast steel and stainless cast steel product for seawater pump of automatic power plant
JPH0931601A (en) * 1995-07-25 1997-02-04 Hitachi Ltd Cast austenitic stainless steel with seawater corrosion resistance and seawater pump

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5218418A (en) * 1975-08-02 1977-02-12 Jgc Corp Stainless cast steel for low temperature use
JPS60121098A (en) * 1983-12-05 1985-06-28 Kawasaki Steel Corp Prevention of hydrogen peeling crack in build-up welding of austenitic stainless steel
JPH0297647A (en) * 1988-09-30 1990-04-10 Aichi Steel Works Ltd Steel for valve stem having excellent torsional strength and its manufacture
JPH0297648A (en) * 1988-09-30 1990-04-10 Aichi Steel Works Ltd Austenitic stainless steel excellent in creep rupture strength and its production
JP2574917B2 (en) * 1990-03-14 1997-01-22 株式会社日立製作所 Austenitic steel excellent in stress corrosion cracking resistance and its use
US20060266439A1 (en) 2002-07-15 2006-11-30 Maziasz Philip J Heat and corrosion resistant cast austenitic stainless steel alloy with improved high temperature strength
JP3954954B2 (en) * 2002-10-25 2007-08-08 新日本製鐵株式会社 Manufacturing method of austenitic stainless steel and strip slab
CA2528743C (en) * 2003-06-10 2010-11-23 Sumitomo Metal Industries, Ltd. Austenitic stainless steel for hydrogen gas and a method for its manufacture
EP1637785B9 (en) * 2004-09-15 2011-01-05 Sumitomo Metal Industries, Ltd. Steel tube excellent in exfoliation resistance of scale on inner surface
RU2461641C2 (en) * 2007-12-20 2012-09-20 ЭйТиАй ПРОПЕРТИЗ, ИНК. Austenitic stainless steel with low content of nickel and including stabilising elements
CN101845605B (en) * 2009-03-24 2013-01-02 宝山钢铁股份有限公司 Austenitic stainless steel plate with excellent strength at medium and low temperature and manufacturing method thereof

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5487627A (en) * 1977-12-23 1979-07-12 Kubota Ltd Stainless steel for extreme low temperature excellent in weld ability
JPS5547370A (en) * 1978-09-30 1980-04-03 Kubota Ltd Stainless cast steel for cryogenic temperature use
JPS6353244A (en) * 1986-08-25 1988-03-07 Aichi Steel Works Ltd Stainless steel excellent in strength and corrosion resistance and having small anisotropy and its production
JPS63169362A (en) * 1986-12-29 1988-07-13 Aichi Steel Works Ltd Nonmagnetic tool steel
JPH05311337A (en) * 1992-05-08 1993-11-22 Nippon Yakin Kogyo Co Ltd High ductility austenite-ferrite duplex heat resistant steel and its manufacture
JPH06336653A (en) * 1993-05-27 1994-12-06 Agency Of Ind Science & Technol Production of stainless cast steel and stainless cast steel product for seawater pump of automatic power plant
JPH0931601A (en) * 1995-07-25 1997-02-04 Hitachi Ltd Cast austenitic stainless steel with seawater corrosion resistance and seawater pump

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017171178A1 (en) * 2016-03-28 2017-10-05 엘지전자 주식회사 Stainless steel and pipe made thereof
US10627168B2 (en) 2016-03-28 2020-04-21 Lg Electronics Inc. Stainless steel and pipe made thereof

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