JP2022101157A - Ferritic stainless steel casting - Google Patents
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- 238000005266 casting Methods 0.000 title claims abstract description 36
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 28
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 239000010935 stainless steel Substances 0.000 claims description 10
- 229910000859 α-Fe Inorganic materials 0.000 claims description 10
- 150000003839 salts Chemical class 0.000 abstract description 8
- 229910052758 niobium Inorganic materials 0.000 abstract description 5
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 229910052804 chromium Inorganic materials 0.000 abstract description 3
- 229910052748 manganese Inorganic materials 0.000 abstract description 3
- 230000007797 corrosion Effects 0.000 description 29
- 238000005260 corrosion Methods 0.000 description 29
- 230000000694 effects Effects 0.000 description 13
- 229910000831 Steel Inorganic materials 0.000 description 8
- 230000003647 oxidation Effects 0.000 description 8
- 238000007254 oxidation reaction Methods 0.000 description 8
- 239000010959 steel Substances 0.000 description 8
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 150000001247 metal acetylides Chemical class 0.000 description 6
- 239000002184 metal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
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- Treatment Of Steel In Its Molten State (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Continuous Casting (AREA)
Abstract
Description
本発明はフェライト系ステンレス鋼鋳物に関する。 The present invention relates to ferritic stainless steel castings.
たとえば廃棄物焼却炉、バイオマスボイラのような、高温域で腐食ガスと溶融塩が存在するような雰囲気で用いられるノズルや熱交換器のような部品には、高い耐腐食性が求められる。 For example, parts such as nozzles and heat exchangers used in an atmosphere where corrosive gas and molten salt are present in a high temperature region, such as a waste incinerator and a biomass boiler, are required to have high corrosion resistance.
特許文献1には、高温の腐食性燃焼ガス環境下で優れた耐食性及び高温クリープ強度を有するフェライトステンレス鋼として、質量%で、C:0.040%以下、Si:0.40~1.20%、Mn:0.01~0.50%、P:0.040%以下、S:0.030%以下、Cr:22.50~27.50%、Al:0.60~1.40%、Ti:0.10~0.90%、N:0.0500%以下、Nb:0.10~0.90%を含有し、これらの化学成分において、(Ti/48+Nb/93)-(C/12+N/14):0.004~0.025%であり、残部Fe及び不可避不純物 か ら な り 、850℃、9MPaでクリープ破断試験を実施した際の破断までのLaves相の析出増加量が0.20容量%以上であることを特徴とする高温腐食性及び高温クリープ強度に優れたフェライト系ステンレス鋼が開示されている。 Patent Document 1 describes a ferritic stainless steel having excellent corrosion resistance and high-temperature creep strength under a high-temperature corrosive combustion gas environment, in terms of mass%, C: 0.040% or less, Si: 0.40 to 1.20. %, Mn: 0.01 to 0.50%, P: 0.040% or less, S: 0.030% or less, Cr: 22.50 to 27.50%, Al: 0.60 to 1.40%. , Ti: 0.10 to 0.90%, N: 0.0500% or less, Nb: 0.10 to 0.90%, and in these chemical components, (Ti / 48 + Nb / 93)-(C. / 12 + N / 14): 0.004 to 0.025%, and the amount of increase in precipitation of the Loves phase until breakage when the creep breakage test was carried out at 850 ° C. and 9 MPa from the balance Fe and unavoidable impurities. A ferritic stainless steel having excellent high-temperature corrosiveness and high-temperature creep strength, which is characterized by having a volume of 0.20% by volume or more, is disclosed.
特許文献2には、高温にさらされる焼却炉の火格子材料として使用することができる、Feを主材とし、重量パーセントにおいてCを0.04~0.16、Crを24.0~31.0、Alを1~4.9、Siを0.6~4.9添加したことを特徴とする耐熱鋼が開示されている。 In Patent Document 2, Fe is used as a main material, and C is 0.04 to 0.16 and Cr is 24.0 to 31. In terms of weight percent, which can be used as a grate material for an incinerator exposed to high temperatures. A heat-resistant steel characterized by adding 0, Al from 1 to 4.9 and Si from 0.6 to 4.9 is disclosed.
鋳物の合金組織は、塑性加工により生じた合金組織とは異なり、鋳造時の凝固組織がそのまま残ったものである。鋳物は、鋳型に溶湯を流し込むことにより任意の形状が得られるので、塑性加工品に比べて製造が容易であるという利点がある。一方、鋳造の凝固組織は、ミクロ偏析が大きく、結晶粒が粗大である。偏析が大きいと基地(マトリックス)が腐食しやすくなり、結晶粒が大きいと粒界が腐食しやすくなるため、鋳物の耐腐食性は塑性加工品に比較して低下すると言われている。 The alloy structure of the casting is different from the alloy structure generated by plastic working, and the solidified structure at the time of casting remains as it is. Since an arbitrary shape can be obtained by pouring molten metal into a mold, the casting has an advantage that it is easier to manufacture than a plastically worked product. On the other hand, the solidified structure of casting has a large microsegregation and coarse crystal grains. It is said that the corrosion resistance of cast products is lower than that of plastically worked products because the matrix is liable to corrode when the segregation is large and the grain boundaries are liable to corrode when the crystal grains are large.
鋳物においては、高温域で腐食性ガスと溶融塩がともに存在する雰囲気での耐腐食性、及び焼却炉等の稼働時の加熱と冷却の繰り返し熱変形による耐応力割れに関して、なお向上の余地がある。 In castings, there is still room for improvement in corrosion resistance in an atmosphere where both corrosive gas and molten salt are present in the high temperature range, and stress corrosion cracking due to repeated thermal deformation of heating and cooling during operation of incinerators and the like. be.
本発明は、高温域の腐食性ガスと溶融塩の存在する雰囲気で優れた耐腐食性を有し、さらに、優れた延性を備え、焼却炉用部品に用いることができるフェライト系ステンレス鋼鋳物を提供することを課題とする。 The present invention provides a ferritic stainless steel casting that has excellent corrosion resistance in the presence of corrosive gas and molten salt in the high temperature range, has excellent ductility, and can be used for parts for incinerators. The challenge is to provide.
本発明者らは高温域の腐食性ガスと溶融塩の存在する雰囲気での耐腐食性、高い延性を備えたフェライト系ステンレス鋼鋳物について鋭意検討した。その結果、Si含有量を高め、さらにAl2O3の保護被膜を形成することにより高い耐腐食性が得られ、Alの添加量を調整し、NbでCを固定することにより高い延性が得られることに加え粒界腐食を抑制し耐腐食性がより向上することを知見した。 The present inventors have diligently studied a ferritic stainless steel casting having corrosion resistance and high ductility in an atmosphere in which a corrosive gas and a molten salt are present in a high temperature region. As a result, high corrosion resistance can be obtained by increasing the Si content and further forming a protective film of Al 2 O 3 , and high ductility can be obtained by adjusting the amount of Al added and fixing C with Nb. In addition to this, it was found that intergranular corrosion was suppressed and corrosion resistance was further improved.
本発明は上記の知見に基づきなされたものであって、その要旨は以下のとおりである。 The present invention has been made based on the above findings, and the gist thereof is as follows.
(1)質量%で、C:0.08%以下、Si:1.50~3.50%、Mn:0.30~2.00%、Cr:20.00~33.00%、Nb:0.10~1.50%、及びAl:0.30~2.50%を含有し、残部がFe及び不可避的不純物であることを特徴とするフェライト系ステンレス鋼鋳物。 (1) In terms of mass%, C: 0.08% or less, Si: 1.50 to 3.50%, Mn: 0.30 to 2.00%, Cr: 20.00 to 33.00%, Nb: A ferritic stainless steel casting containing 0.10 to 1.50% and Al: 0.30 to 2.50%, the balance of which is Fe and unavoidable impurities.
(2)前記Feの一部に代えて、Ni:0~10.00%を含有することを特徴とする前記(1)のフェライト系ステンレス鋼鋳物。 (2) The ferrite-based stainless steel casting according to (1), which contains Ni: 0 to 10.00% instead of a part of Fe.
(3)前記Feの一部に代えて、Mo:0~5.00%を含有することを特徴とする前記(1)又は(2)のフェライト系ステンレス鋼鋳物。 (3) The ferrite-based stainless steel casting according to (1) or (2), which contains Mo: 0 to 5.00% in place of a part of Fe.
(4)前記Feの一部に代えて、W:0~3.00%を含有することを特徴とする前記(1)~(3)のいずれかのフェライト系ステンレス鋼鋳物。 (4) The ferrite-based stainless steel casting according to any one of the above (1) to (3), which contains W: 0 to 3.00% in place of a part of the Fe.
(5)前記Feの一部に代えて、Ti:0~2.00%を含有することを特徴とする前記(1)~(4)のいずれかのフェライト系ステンレス鋼鋳物。 (5) The ferrite-based stainless steel casting according to any one of the above (1) to (4), which contains Ti: 0 to 2.00% in place of a part of the Fe.
本発明によれば、高温域の腐食性ガスと溶融塩の存在する雰囲気で優れた耐腐食性を有し、かつ延性に優れた、焼却炉用部品に用いることができるフェライト系ステンレス鋼鋳物を提供することができる。 According to the present invention, a ferritic stainless steel casting that has excellent corrosion resistance in an atmosphere in the presence of corrosive gas and molten salt in a high temperature region and has excellent ductility and can be used for parts for incinerators is provided. Can be provided.
本発明におけるフェライト系ステンレス鋼鋳物の化学成分について説明する。以下、含有量における「%」は「質量%」を意味するものとする。 The chemical composition of the ferritic stainless steel casting in the present invention will be described. Hereinafter, "%" in the content shall mean "mass%".
C:0.08%以下
Cは鋼の強度の上昇に寄与するので、必要に応じて含有させてもよい。この効果は少量でも得られるが、C量を0.01%以上、又は0.02%以上とすると効果的であり、好ましい。Cの含有量が多くなると延性が低下し、さらに鋳造割れが生じやすくなる。また、Cは鋼中のCrと結合して結晶粒界にCr炭化物として析出し、基地のCr濃度が低下して高温での耐酸化性、耐腐食性の低下につながる。したがって、Cの含有量は0.08%以下、好ましくは0.06%以下、より好ましくは0.05%以下とする。本発明のフェライト系ステンレス鋼鋳物においては、Cは必須の元素ではなく、含有量は0でもよい。
C: 0.08% or less C contributes to the increase in the strength of the steel, and may be contained if necessary. Although this effect can be obtained even in a small amount, it is effective when the amount of C is 0.01% or more, or 0.02% or more, which is preferable. As the C content increases, the ductility decreases, and casting cracks are more likely to occur. Further, C is bonded to Cr in the steel and precipitated as Cr carbide at the grain boundaries, and the Cr concentration at the matrix is lowered, which leads to deterioration of oxidation resistance and corrosion resistance at high temperature. Therefore, the content of C is 0.08% or less, preferably 0.06% or less, and more preferably 0.05% or less. In the ferrite-based stainless steel casting of the present invention, C is not an essential element, and the content may be 0.
Si:1.50~3.50%
Siは耐酸化性に効果があり、とくに高温での耐酸化性、耐腐食性の向上に効果がある。耐酸化性、耐腐食性向上の効果を得るためには1.50%以上のSiが必要であり、2.00%以上が好ましく、2.50%以上がより好ましく、2.70%以上がさらの好ましい。また、Siはシグマ層の生成も促進し高温で長時間使用した場合の脆化も危惧されるため、3.50%以下にすることが必要であり、3.30%以下が好ましく、3.20%以下がより好ましく、3.00%以下がさらに好ましい。
Si: 1.50 to 3.50%
Si is effective in oxidation resistance, and is particularly effective in improving oxidation resistance and corrosion resistance at high temperatures. In order to obtain the effect of improving oxidation resistance and corrosion resistance, 1.50% or more of Si is required, preferably 2.00% or more, more preferably 2.50% or more, and 2.70% or more. Further preferred. In addition, Si promotes the formation of a sigma layer and may cause embrittlement when used at high temperature for a long time. Therefore, it is necessary to make it 3.50% or less, preferably 3.30% or less. % Or less is more preferable, and 3.00% or less is further preferable.
Mn:0.30~1.50%
Mnは、オーステナイト形成元素であり、また、脱酸剤、脱硫剤として有用な成分である。その効果を十分に得るために、Mnの含有量は0.30%以上とすることが必要であり、0.40%以上が好ましく、0.50%以上がさらに好ましい。脆化の防止や、クリープ強度、耐腐食性の低下の防止の観点から、Mnの含有量は1.50%以下とすることが必要であり、1.00%以下が好ましく、0.80%以下がさらに好ましい。
Mn: 0.30 to 1.50%
Mn is an austenite-forming element and is a useful component as a deoxidizing agent and a desulfurizing agent. In order to sufficiently obtain the effect, the Mn content needs to be 0.30% or more, preferably 0.40% or more, and more preferably 0.50% or more. From the viewpoint of preventing embrittlement and deterioration of creep strength and corrosion resistance, the Mn content needs to be 1.50% or less, preferably 1.00% or less, preferably 0.80%. The following is more preferable.
Cr:20.00~33.00%
Crは高温強度、及び高温での耐酸化性、耐腐食性を向上する元素である。その効果を十分に得るために、Crの含有量は20.00%以上とすることが必要であり、23.00%以上が好ましく、26.00%以上がより好ましい。たとえばバイオマスボイラのような、溶融塩化物が付着するような環境下では、Crの含有量が多くなりすぎると、揮発性のCr2O2Cl2が形成され、高温での耐酸化性、耐腐食性が低下するので、Crの含有量は33.00%以下とすることが必要であり、32.00%以下が好ましく、31.00%以下がより好ましい。
Cr: 20.00 to 33.00%
Cr is an element that improves high-temperature strength, oxidation resistance at high temperatures, and corrosion resistance. In order to sufficiently obtain the effect, the Cr content needs to be 20.00% or more, preferably 23.00% or more, and more preferably 26.00% or more. For example, in an environment such as a biomass boiler where molten chloride adheres, if the Cr content becomes too high, volatile Cr 2 O 2 Cl 2 is formed, and oxidation resistance and resistance at high temperatures are achieved. Since the corrosiveness is lowered, the Cr content needs to be 33.00% or less, preferably 32.00% or less, and more preferably 31.00% or less.
Nb:0.10~1.50%
Nbは炭化物を形成しやすく、鋼中のCを固定してCr炭化物の析出を抑制することにより、高温強度と延性の低下を防ぐことができる。この効果を得るために、含有量は0.1%以上とすることが必要であり、0.20%以上が好ましく、0.40%以上がより好ましい。含有量が1.50%を超えると効果が飽和し、クリープ強度、耐酸化性、耐腐食性が低下するので、1.50%以下とすることが必要であり、1.30%以下が好ましく、1.20%以下がより好ましい。
Nb: 0.10 to 1.50%
Nb easily forms carbides, and by fixing C in the steel and suppressing the precipitation of Cr carbides, it is possible to prevent a decrease in high-temperature strength and ductility. In order to obtain this effect, the content needs to be 0.1% or more, preferably 0.20% or more, and more preferably 0.40% or more. If the content exceeds 1.50%, the effect is saturated and creep strength, oxidation resistance, and corrosion resistance are lowered. Therefore, it is necessary to set it to 1.50% or less, preferably 1.30% or less. , 1.20% or less is more preferable.
本発明のフェライト系ステンレス鋼鋳物ではCr炭化物(M23C6)はほとんど析出せず、好ましくは面積率で1.0%以下、より好ましくは0.5%以下、さらに好ましくは0.1%以下である。 In the ferritic stainless steel casting of the present invention, Cr carbide (M 23 C 6 ) hardly precipitates, and the area ratio is preferably 1.0% or less, more preferably 0.5% or less, still more preferably 0.1%. It is as follows.
Al:0.30~2.50%
Alは、脱酸能の高い元素であり、製鋼の際に脱酸剤として用いられる。また、耐溶融塩腐食に強いAl2O3の保護被膜を形成することで耐腐食性を向上する。この効果を得るために、含有量は0.30%以上とすることが必要であり、0.50%以上が好ましく、0.80%以上がより好ましい。含有量が2.50%を超えると効果が飽和し、クリープ強度、耐酸化性、耐腐食性が低下するので、2.50%以下とし、2.30%以下が好ましく、2.10%以下がより好ましい。
Al: 0.30 to 2.50%
Al is an element having a high deoxidizing ability and is used as a deoxidizing agent in steelmaking. In addition, corrosion resistance is improved by forming a protective film of Al 2 O 3 that is resistant to molten salt corrosion. In order to obtain this effect, the content needs to be 0.30% or more, preferably 0.50% or more, and more preferably 0.80% or more. If the content exceeds 2.50%, the effect is saturated and the creep strength, oxidation resistance, and corrosion resistance are lowered. Therefore, the content is set to 2.50% or less, preferably 2.30% or less, and 2.10% or less. Is more preferable.
化学成分の残部はFe及び不可避的不純物である。ただし、Feの一部に代えて、以下に説明する元素を含有してもよい。以下に説明する元素の含有は任意であり、必須ではない。 The rest of the chemical composition is Fe and unavoidable impurities. However, instead of a part of Fe, an element described below may be contained. The inclusion of the elements described below is optional and not essential.
Ni:0~10.00%
Niは常温延性を向上する元素であり、10.00%以下の範囲で含有させてもよい。この効果は微量の含有でも得られるが、0.10%以上含有させると効果的である。
Ni: 0 to 10.00%
Ni is an element that improves ductility at room temperature and may be contained in the range of 10.00% or less. This effect can be obtained even if it is contained in a small amount, but it is effective if it is contained in an amount of 0.10% or more.
Mo:0~5.00%
Moは耐腐食性を高める効果があり、5.00%以下の範囲で含有させてもよい。この効果は微量の含有でも得られるが、0.50%以上含有させると効果的である。
Mo: 0 to 5.00%
Mo has an effect of increasing corrosion resistance and may be contained in a range of 5.00% or less. This effect can be obtained even if it is contained in a small amount, but it is effective if it is contained in an amount of 0.50% or more.
W:0~3.00%
WはNbと同様炭化物を形成しやすく、鋼中のCを固定してCr炭化物の析出を抑制することができ、高温強度の低下を防ぐことができる元素であり、3.00%以下の範囲で含有させてもよい。この効果は微量の含有でも得られるが、0.20%以上含有させると効果的である。
W: 0 to 3.00%
Like Nb, W is an element that easily forms carbides, can fix C in steel to suppress precipitation of Cr carbides, and can prevent a decrease in high-temperature strength, and is in the range of 3.00% or less. It may be contained in. This effect can be obtained even if it is contained in a small amount, but it is effective if it is contained in an amount of 0.20% or more.
Ti:0~2.00%
TiはNbと同様炭化物を形成しやすく、鋼中のCを固定してCr炭化物の析出を抑制することができ、高温強度の低下を防ぐことができる元素であり、2.00%以下の範囲で含有させてもよい。この効果は微量の含有でも得られるが、0.10%以上含有させると効果的である。
Ti: 0 to 2.00%
Like Nb, Ti is an element that easily forms carbides, can fix C in steel to suppress precipitation of Cr carbides, and can prevent a decrease in high-temperature strength, and is in the range of 2.00% or less. It may be contained in. This effect can be obtained even if it is contained in a small amount, but it is effective if it is contained in an amount of 0.10% or more.
次に、本発明のフェライト系ステンレス鋼鋳物の製造方法について説明する。 Next, a method for manufacturing the ferritic stainless steel casting of the present invention will be described.
本発明の製造方法は、特に限定されるものではなく、常法によればよい。はじめに、上述した成分組成を有する溶湯を調整し、溶湯を鋳型に注湯し、注湯された溶湯を冷却して凝固させる。鋳型や、鋳型への溶鋼の注入装置、注入方法は特に限定されるものではなく、公知の装置、方法を用いればよい。 The production method of the present invention is not particularly limited, and a conventional method may be used. First, a molten metal having the above-mentioned composition is prepared, the molten metal is poured into a mold, and the poured molten metal is cooled and solidified. The mold, the apparatus for injecting molten steel into the mold, and the injection method are not particularly limited, and known apparatus and methods may be used.
本発明の化学成分を有する溶湯を鋳造することにより、特別な製法を用いることなく、鋳造ままで優れた耐腐食性、延性を有するフェライト系ステンレス鋼鋳物を得ることが可能である。 By casting a molten metal having the chemical composition of the present invention, it is possible to obtain a ferritic stainless steel casting having excellent corrosion resistance and ductility as it is cast without using a special manufacturing method.
本発明の鋳物は原則として鋳放しのまま使用されるが、必要に応じて、900~1200℃に加熱し、2~24Hr保持する溶体化処理を施すことができる。 As a general rule, the casting of the present invention is used as it is, but if necessary, it can be heated to 900 to 1200 ° C. and subjected to a solution treatment for holding 2 to 24 hours.
なお、本発明のフェライト系ステンレス鋼鋳物は、所定の形状の鋳型に鋳込んだ後に塑性加工を施さない鋼であり、熱間圧延や鍛造のような塑性加工が施された合金とは区別される。すなわち、鋳物は合金組織として鋳造したままの凝固組織が残ったものであるのに対し、塑性加工が施された合金は加工により生じた合金組織を有するものであり、その組織は大きく異なるものである。本発明の鋳物では、結晶粒の大きさ(面積円相当径)は0.2~10.0mm程度となる。 The ferritic stainless steel casting of the present invention is a steel that is not subjected to plastic working after being cast into a mold having a predetermined shape, and is distinguished from an alloy that has been subjected to plastic working such as hot rolling or forging. To. That is, the casting has a solidified structure as cast as an alloy structure, whereas the plastically processed alloy has an alloy structure produced by the processing, and the structure is significantly different. be. In the casting of the present invention, the size of the crystal grains (diameter equivalent to the area circle) is about 0.2 to 10.0 mm.
以下、実施例を用いて、本発明について詳細に説明する。 Hereinafter, the present invention will be described in detail with reference to examples.
表1に示す成分組成を有するフェライト系ステンレス鋼鋳物を作製し、腐食試験に供した。腐食試験は、作製したフェライト系ステンレス鋼鋳物から20×20×3mmの試験片を採取し、表2に示す試験条件で行い、耐腐食性を、腐食減量(mg/cm2)で評価し、70mg/cm2以下であれば耐腐食性に優れていると判断した。 Ferritic stainless steel castings having the composition shown in Table 1 were prepared and subjected to a corrosion test. The corrosion test was carried out by collecting a 20 × 20 × 3 mm test piece from the produced ferrite stainless steel casting and performing it under the test conditions shown in Table 2, and the corrosion resistance was evaluated by the corrosion weight loss (mg / cm 2 ). If it was 70 mg / cm 2 or less, it was judged to have excellent corrosion resistance.
また、φ10×50Lの標点間距離を有する試験片を採取し、JIS Z2241:2011に準拠して常温における絞り値を測定することで常温延性評価し、2.5%以上であれば常温延性が優れていると判断した。 Further, a test piece having a distance between reference points of φ10 × 50 L is collected and evaluated for room temperature ductility by measuring the aperture value at room temperature in accordance with JIS Z2241: 2011. If it is 2.5% or more, room temperature ductility is evaluated. Was judged to be excellent.
本発明によれば、高温域の腐食性ガスと溶融塩の存在する雰囲気で,優れた耐腐食性を有し、かつ延性に優れた、焼却炉用部品に好適なフェライト系ステンレス鋼鋳物が得られることが確認できた。 According to the present invention, a ferritic stainless steel casting suitable for incinerator parts, which has excellent corrosion resistance and ductility in an atmosphere where corrosive gas and molten salt are present in a high temperature range, can be obtained. I was able to confirm that it was possible.
本発明の要件を満たさない比較例は、耐腐食性、延性の一方、又は両方が劣る結果となった。 Comparative examples that do not meet the requirements of the present invention resulted in inferior corrosion resistance, ductility, or both.
Claims (5)
C :0.08%以下、
Si:1.50~3.50%、
Mn:0.30~2.00%、
Cr:20.00~33.00%、
Nb:0.10~1.50%、及び
Al:0.30~2.50%
を含有し、残部がFe及び不可避的不純物であることを特徴とするフェライト系ステンレス鋼鋳物。 By mass%,
C: 0.08% or less,
Si: 1.50 to 3.50%,
Mn: 0.30 to 2.00%,
Cr: 20.00 to 33.00%,
Nb: 0.10 to 1.50%, and Al: 0.30 to 2.50%
Ferritic stainless steel casting, characterized in that the balance is Fe and unavoidable impurities.
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