JP6667171B2 - Al-containing ferritic stainless steel - Google Patents
Al-containing ferritic stainless steel Download PDFInfo
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- 229910001220 stainless steel Inorganic materials 0.000 title claims description 21
- 229910000831 Steel Inorganic materials 0.000 claims description 47
- 239000010959 steel Substances 0.000 claims description 47
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 description 46
- 238000007254 oxidation reaction Methods 0.000 description 46
- 239000010936 titanium Substances 0.000 description 29
- 239000010955 niobium Substances 0.000 description 27
- 239000011651 chromium Substances 0.000 description 26
- 230000000694 effects Effects 0.000 description 21
- 229910052804 chromium Inorganic materials 0.000 description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- 229910052719 titanium Inorganic materials 0.000 description 15
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 13
- 229910052742 iron Inorganic materials 0.000 description 12
- 229910052758 niobium Inorganic materials 0.000 description 12
- 239000002436 steel type Substances 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 9
- 239000010410 layer Substances 0.000 description 9
- 239000011572 manganese Substances 0.000 description 8
- 229910052761 rare earth metal Inorganic materials 0.000 description 8
- 229910052782 aluminium Inorganic materials 0.000 description 7
- 239000010949 copper Substances 0.000 description 7
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 238000005498 polishing Methods 0.000 description 6
- 238000004445 quantitative analysis Methods 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 230000002411 adverse Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 229910001651 emery Inorganic materials 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 230000004584 weight gain Effects 0.000 description 2
- 235000019786 weight gain Nutrition 0.000 description 2
- 241000219307 Atriplex rosea Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910017060 Fe Cr Inorganic materials 0.000 description 1
- 229910002544 Fe-Cr Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000000988 reflection electron microscopy Methods 0.000 description 1
- 238000000550 scanning electron microscopy energy dispersive X-ray spectroscopy Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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- Heat Treatment Of Sheet Steel (AREA)
Description
本発明は、高温環境で使用されるＡｌ含有フェライト系ステンレス鋼に関する。 The present invention relates to an Al-containing ferritic stainless steel used in a high-temperature environment.
高温環境で使用されるステンレス鋼としては、例えば特許文献１ないし５に示すように、Ｔｉを添加したＡｌ含有フェライトステンレス鋼、または、ＮｂおよびＴｉを複合添加したＡｌ含有フェライトステンレス鋼が知られている。 As stainless steels used in a high-temperature environment, for example, as shown in Patent Documents 1 to 5, Al-containing ferritic stainless steel to which Ti is added, or Al-containing ferritic stainless steel to which Nb and Ti are combined are known. I have.
このようなＡｌ含有フェライトステンレス鋼では、Ｔｉの添加や、ＮｂおよびＴｉの複合添加により、ＣおよびＮが固定されて、加工性や耐酸化性等が改善されている。 In such an Al-containing ferritic stainless steel, C and N are fixed by the addition of Ti and the combined addition of Nb and Ti, so that the workability and oxidation resistance are improved.
しかしながら、上述の特許文献１ないし５のように、Ｔｉを添加したＡｌ含有フェライトステンレス鋼、および、ＮｂおよびＴｉを複合添加したＡｌ含有フェライトステンレス鋼では、Ｔｉ含有量が多くなりすぎると、鋼の外層側にＴｉを含むＦｅ−Ｃｒ系酸化物が生成されて、Ａｌ系酸化物（Ａｌ２Ｏ３皮膜）が均一に形成されにくく、耐高温酸化性が低下する可能性がある。 However, in the Al-containing ferritic stainless steel to which Ti is added and the Al-containing ferritic stainless steel to which Nb and Ti are added as in Patent Documents 1 to 5 described above, if the Ti content is too large, the steel becomes An Fe-Cr-based oxide containing Ti is generated on the outer layer side, so that an Al-based oxide (Al 2 O 3 film) is difficult to be uniformly formed, and high-temperature oxidation resistance may be reduced.
また、耐高温酸化性を向上させるために、Ａｌを多量に添加しすぎると、加工性が低下してしまう。 Also, if a large amount of Al is added in order to improve the high-temperature oxidation resistance, the workability is reduced.
また、例えば、排ガス経路部材、燃料電池システムおよび発熱体等の材料として高温環境での使用を考慮すると、高温強度が高い方が好ましいが、Ｔｉを多量に添加しても、高温強度は向上しにくい。 In addition, for example, considering use in a high-temperature environment as a material for an exhaust gas path member, a fuel cell system, a heating element, and the like, it is preferable that the high-temperature strength be high. Hateful.
本発明はこのような点に鑑みなされたもので、耐高温酸化性、高温強度および加工性に優れたＡｌ含有フェライト系ステンレス鋼を提供することを目的とする。 The present invention has been made in view of such a point, and an object of the present invention is to provide an Al-containing ferritic stainless steel excellent in high-temperature oxidation resistance, high-temperature strength, and workability.
請求項１に記載されたＡｌ含有フェライト系ステンレス鋼は、Ｃ：０．０２５質量％以下、Ｓｉ：０．１質量％以上１．０質量％以下、Ｍｎ：０．８質量％以下、Ｐ：０．０５質量％以下、Ｓ：０．０１質量％以下、Ｎｉ：０．５質量％以下、Ｃｒ：１５．０質量％以上２３．０質量％以下、Ａｌ：２．０質量％以上４．０質量％以下、Ｎ：０．０２５質量％以下、Ｎｂ：０．１質量％以上０．６質量％以下を含有し、残部がＦｅおよび不可避的不純物からなり、鋼表面のマイクロビッカース０．１ｋｇで測定した硬さをＨＶａとし、鋼の厚み方向中央部のマイクロビッカース０．１ｋｇで測定した硬さをＨＶｂとすると、ＨＶａ−ＨＶｂ≧３０であり、７００℃での０．２％耐力が１００ＭＰａ以上であるものである。 In the Al-containing ferritic stainless steel according to claim 1, C: 0.025% by mass or less, Si: 0.1% by mass to 1.0% by mass, Mn: 0.8% by mass or less, P: 0.05% by mass or less, S: 0.01% by mass or less, Ni: 0.5% by mass or less, Cr: 15.0% by mass to 23.0% by mass, Al: 2.0% by mass or more 0% by mass or less, N: 0.025% by mass or less, Nb: 0.1% by mass or more and 0.6% by mass or less, the balance being Fe and inevitable impurities, and 0.1 kg of micro Vickers on the steel surface in the hardness measured with HVa, when the hardness measured by a micro Vickers 0.1kg of thickness direction center portion of the steel and HVb, HVa-HVb ≧ 30 der is, 0.2% yield strength at 700 ° C. It is 100 MPa or more .
請求項２に記載されたＡｌ含有フェライト系ステンレス鋼は、請求項１記載のＡｌ含有フェライト系ステンレス鋼において、Ｍｏ：０．０５質量％以上０．５質量％以下、Ｖ：０．０５質量％以上０．５質量％以下、Ｃｕ：０．０５質量％以上０．５質量％以下、Ｚｒ：０．０５質量％以上０．５質量％以下、Ｂ：０．００５質量％以下およびＲＥＭ：０．００１質量％以上０．０５質量％以下の少なくとも１種を含有するものである。 The Al-containing ferritic stainless steel according to the second aspect is the Al-containing ferritic stainless steel according to the first aspect, in which Mo: 0.05% by mass or more and 0.5% by mass or less, and V: 0.05% by mass. 0.5% by mass or less, Cu: 0.05% by mass or less, 0.5% by mass or less, Zr: 0.05% by mass or more and 0.5% by mass or less, B: 0.005% by mass or less, and REM: 0 It contains at least one of 0.001% by mass or more and 0.05% by mass or less .
本発明によれば、Ｎｂが添加されているとともに、ＨＶａ−ＨＶｂ≧３０であり、かつ、７００℃での０．２％耐力が１００ＭＰａ以上であるため、耐高温酸化性、高温強度および加工性を向上できる。 According to the present invention, together with Nb is added, HVa-HVb ≧ 30 der is, and, since the 0.2% proof stress at 700 ° C. is not less than 100 MPa, high-temperature oxidation resistance, high temperature strength and processability Performance can be improved.
以下、本発明の一実施の形態の構成について詳細に説明する。 Hereinafter, the configuration of an embodiment of the present invention will be described in detail.
一実施の形態に係るＡｌ含有フェライト系ステンレス鋼は、０．０２５質量％以下のＣ（炭素）、０．１質量％以上１．０質量％以下のＳｉ（ケイ素）、０．８質量％以下のＭｎ（マンガン）、０．０５質量％以下のＰ（リン）、０．０１質量％以下のＳ（硫黄）、０．５質量％以下のＮｉ（ニッケル）、１５．０質量％以上２３．０質量％以下のＣｒ（クロム）、２．０質量％以上４．０質量％以下のＡｌ（アルミニウム）、０．０２５質量％以下のＮ（窒素）、０．１質量％以上０．６質量％以下のＮｂ（ニオブ）を含有し、残部がＦｅ（鉄）および不可避的不純物からなる。 The Al-containing ferritic stainless steel according to one embodiment has C (carbon) of 0.025% by mass or less, Si (silicon) of 0.1 to 1.0% by mass, and 0.8% by mass or less. Mn (manganese), P (phosphorus) of 0.05% by mass or less, S (sulfur) of 0.01% by mass or less, Ni (nickel) of 0.5% by mass or less, 15.0% by mass or more 0 mass% or less of Cr (chromium), 2.0 mass% or more and 4.0 mass% or less of Al (aluminum), 0.025 mass% or less of N (nitrogen), 0.1 mass% or more and 0.6 mass% % Of Nb (niobium), the balance being Fe (iron) and unavoidable impurities.
また、必要に応じて、０．０５質量％以上０．５質量％以下のＭｏ（モリブデン）、０．０５質量％以上０．５質量％以下のＶ（バナジウム）、０．０５質量％以上０．５質量％以下のＣｕ（銅）、０．０５質量％以上０．５質量％以下のＺｒ（ジルコニウム）、０．００５質量％以下のＢ（ホウ素）および０．００１質量％以上０．０５質量％以下のＲＥＭ（希土類元素）の少なくとも１種を含有してもよい。 Further, if necessary, Mo (molybdenum) of 0.05% to 0.5% by mass, V (vanadium) of 0.05% to 0.5% by mass, and 0.05% to 0% 0.5 mass% or less of Cu (copper), 0.05 mass% or more and 0.5 mass% or less of Zr (zirconium), 0.005 mass% or less of B (boron), and 0.001 mass% or more of 0.05 It may contain at least one kind of REM (rare earth element) by mass% or less.
Ｃは、高温強度、特にクリープ特性を向上させる作用を奏する元素であるが、Ｃ含有量が高くなると、加速酸化が発生しやすくなる。また、Ａｌを含有するフェライト系ステンレス鋼においてＣ含有量が高くなると、スラブやホットコイルの靭性が低下し、製造性が低下する。したがって、加速酸化や製造性の低下の観点から、Ｃ含有量は、０．０２５質量％以下とする。 C is an element having an effect of improving the high-temperature strength, particularly the creep characteristics, but when the C content is high, accelerated oxidation is likely to occur. Also, when the C content in the Al-containing ferritic stainless steel increases, the toughness of the slab and the hot coil decreases, and the manufacturability decreases. Therefore, the C content is set to 0.025% by mass or less from the viewpoint of accelerated oxidation and reduction in productivity.
Ｓｉは、赤スケールの生成を抑制する作用を有し、この作用を奏するには０．１質量％以上含有させる必要がある。一方、Ｓｉを１．０質量％を超えて過剰に添加すると、靭性および加工性を低下させる可能性がある。したがって、Ｓｉ含有量は、０．１質量％以上１．０質量％以下とする。 Si has an effect of suppressing the generation of red scale, and it is necessary to contain 0.1% by mass or more to exhibit this effect. On the other hand, if Si is added in excess of 1.0% by mass, toughness and workability may be reduced. Therefore, the Si content is set to 0.1% by mass or more and 1.0% by mass or less.
Ｍｎは、高温酸化、特にスケール剥離を抑制する作用を奏する元素であるが、Ｍｎ系酸化物を生成して、緻密なＡｌ酸化物層の形成を阻害するため、０．８質量％を超えて過剰に添加すると、耐高温酸化性に悪影響を及ぼす可能性がある。したがって、Ｍｎ含有量は、０．８質量％以下とする。 Mn is an element having an effect of suppressing high-temperature oxidation, particularly scale exfoliation. However, since Mn generates a Mn-based oxide and hinders formation of a dense Al oxide layer, Mn exceeds 0.8% by mass. Excessive addition may adversely affect high-temperature oxidation resistance. Therefore, the Mn content is set to 0.8% by mass or less.
Ｐは、耐高温酸化性および熱延板の靭性に悪影響を及ぼす。したがって、Ｐの含有量は、０．０５質量％以下とする。 P adversely affects high-temperature oxidation resistance and toughness of a hot-rolled sheet. Therefore, the content of P is set to 0.05% by mass or less.
Ｓは、鋼中に不可避的に含まれる成分であり、Ａｌ２Ｏ３皮膜の形成を著しく阻害するため、できるだけ含有量を低減することが好ましい。したがって、Ｓ含有量は、０．０１質量％以下とする。 S is a component inevitably contained in steel, and significantly inhibits the formation of an Al 2 O 3 film. Therefore, it is preferable to reduce the content of S as much as possible. Therefore, the S content is set to 0.01% by mass or less.
Ｎｉは、加工性の低下を防止する作用を奏する元素であるが、０．５質量％を超えて過剰に添加すると、オーステナイト相の析出によって熱疲労特性が低下する可能性がある。したがって、Ｎｉ含有量は、０．５質量％以下とする。 Ni is an element having an effect of preventing a decrease in workability. However, if Ni is added in excess of 0.5% by mass, the austenite phase may precipitate to lower the thermal fatigue characteristics. Therefore, the Ni content is set to 0.5% by mass or less.
Ｃｒは、耐高温酸化性を向上させる元素として基本的かつ有効な元素であり、良好な耐高温酸化性を得るためには、１５．０質量％以上添加する必要がある。一方、Ｃｒを２３．０質量％を超えて過剰に添加すると、スラブやホットコイルの靭性を低下させる可能性がある。したがって、Ｃｒ含有量は、１５．０質量％以上２３．０質量％以下とする。 Cr is a basic and effective element for improving high-temperature oxidation resistance, and it is necessary to add 15.0% by mass or more in order to obtain good high-temperature oxidation resistance. On the other hand, if Cr is added in excess of 23.0% by mass, the toughness of the slab or hot coil may be reduced. Therefore, the Cr content is 15.0% by mass or more and 23.0% by mass or less.
Ａｌは、Ｃｒと同様に耐高温酸化性およびＣｒ蒸発を抑制するために最も重要な元素であり、耐高温酸化性を向上させるために、鋼表面に緻密なＡｌ系酸化物を形成するには、２．０質量％以上含有させる必要がある。一方、Ａｌを４．０質量％を超えて過剰に添加すると、スラブやホットコイルの靭性を低下させる可能性や、製品加工時の二次加工脆性温度を上昇させる可能性がある。したがって、Ａｌ含有量は、２．０質量％以上４．０質量％以下とする。 Al is the most important element for suppressing high-temperature oxidation resistance and Cr evaporation like Cr, and in order to improve the high-temperature oxidation resistance, it is necessary to form a dense Al-based oxide on the steel surface. , 2.0% by mass or more. On the other hand, if Al is added in excess of 4.0% by mass, the toughness of the slab or hot coil may be reduced, and the secondary working brittle temperature during product processing may be increased. Therefore, the Al content is set to 2.0% by mass or more and 4.0% by mass or less.
Ｎは、高温強度およびクリープ特性を向上させる作用を奏する元素であるが、鋼中のＡｌと結合しＡｌＮを形成して加速酸化の起点となる。したがって、耐高温酸化性の向上のために、Ｎ含有量は、０．０２５質量％以下とする。 N is an element having an effect of improving high-temperature strength and creep characteristics, but combines with Al in steel to form AlN and becomes a starting point of accelerated oxidation. Therefore, in order to improve the high-temperature oxidation resistance, the N content is set to 0.025% by mass or less.
Ｎｂは、鋼中のＣやＮと結合して靭性を著しく向上させる作用を奏する。また、Ｎｂを添加すると、高温強度が向上するとともに、Ａｌ２Ｏ３皮膜の形成を促進し、かつ、酸化皮膜が成長する過程で生じる応力を緩和させて、材料の変形を防止する。これらの作用を奏するには、Ｎｂを０．１質量％以上添加する必要がある。一方、Ｎｂを０．６質量％を超えて過剰に添加すると、靭性が低下する可能性がある。したがって、Ｎｂ含有量は、０．１質量％以上０．６質量％以下とする。 Nb has an effect of combining with C and N in steel to significantly improve toughness. When Nb is added, the high-temperature strength is improved, the formation of the Al 2 O 3 film is promoted, and the stress generated in the process of growing the oxide film is relaxed, thereby preventing the material from being deformed. In order to exert these effects, it is necessary to add 0.1% by mass or more of Nb. On the other hand, if Nb is added in excess of 0.6% by mass, the toughness may decrease. Therefore, the Nb content is from 0.1% by mass to 0.6% by mass.
Ｍｏは、高温強度を向上させる作用を奏する元素であり、その作用を奏するには０．０５質量％以上添加する必要がある。一方、Ｍｏを０．５質量％を超えて過剰に添加すると、鋼材を硬質化し靭性を低下させる可能性がある。したがって、Ｍｏを含有させる場合のＭｏ含有量は、０．０５質量％以上０．５質量％以下とする。 Mo is an element having an effect of improving the high-temperature strength, and it is necessary to add 0.05% by mass or more to exhibit the effect. On the other hand, if Mo is added in excess of 0.5% by mass, the steel material may be hardened and the toughness may be reduced. Therefore, when Mo is contained, the Mo content is 0.05% by mass or more and 0.5% by mass or less.
Ｖは、加工性および溶接部靭性を向上させる作用を奏する元素であり、その作用を奏するには０．０５質量％以上添加する必要がある。一方、Ｖを０．５質量％を超えて過剰に添加すると靭性が低下する可能性がある。したがって、Ｖを含有させる場合のＶ含有量は、０．０５質量％以上０．５質量％以下とする。 V is an element having an effect of improving workability and weld toughness, and it is necessary to add 0.05% by mass or more to achieve the effect. On the other hand, if V is added in excess of 0.5% by mass, toughness may be reduced. Therefore, when V is contained, the V content is 0.05% by mass or more and 0.5% by mass or less.
Ｃｕは、高温強度を向上させる作用を奏する元素であり、その作用を奏するには０．０５質量％以上添加する必要がある。一方、Ｃｕを０．５質量％を超えて過剰に添加すると、耐高温酸化性や熱間加工性の低下を招く可能性がある。したがって、Ｃｕを含有させる場合のＣｕ含有量は、０．０５質量％以上０．５質量％以下とする。 Cu is an element having an effect of improving the high-temperature strength, and it is necessary to add 0.05% by mass or more to achieve the effect. On the other hand, if Cu is added in excess of 0.5% by mass, there is a possibility that high-temperature oxidation resistance and hot workability may be reduced. Therefore, when Cu is contained, the Cu content is 0.05% by mass or more and 0.5% by mass or less.
Ｚｒは、酸化皮膜強度を向上させて耐高温酸化性を向上させる作用を奏する元素であり、その作用を奏するには０．０５質量％以上添加する必要がある。一方、Ｚｒを０．５質量％を超えて過剰に添加すると、鋼が硬質化して低温靭性の低下を招く可能性がある。したがって、Ｚｒを含有させる場合のＺｒ含有量は、０．０５質量％以上０．５質量％以下とする。 Zr is an element having an effect of improving the strength of an oxide film and improving high-temperature oxidation resistance, and it is necessary to add 0.05% by mass or more in order to achieve the effect. On the other hand, if Zr is added in excess of 0.5% by mass, the steel may be hardened and the low-temperature toughness may be reduced. Therefore, when Zr is contained, the Zr content is 0.05% by mass or more and 0.5% by mass or less.
Ｂは、耐二次加工脆性および耐酸化性を向上させる作用を奏する元素であるが、０．００５質量％を超えて過剰に添加すると、粒界に優先的にボライドが生成するため、耐二次加工脆性が低下する可能性がある。したがって、Ｂを含有させる場合のＢ含有量は、０．００５質量％以下とする。 B is an element having an effect of improving the secondary work brittleness resistance and the oxidation resistance. However, when excessively added in excess of 0.005% by mass, boron is preferentially generated at the grain boundary. Secondary working brittleness may decrease. Therefore, when B is contained, the B content is set to 0.005% by mass or less.
ＲＥＭは、耐高温酸化性を向上させる作用を奏する。すなわち、ＬａおよびＣｅ等のＲＥＭは、Ａｌ酸化皮膜を安定化させ、また、マトリックスと酸化皮膜との密着性を改善することにより、耐高温酸化性を向上させる。また、このような作用を奏するには、ＲＥＭを０．００１質量％以上添加する必要がある。一方、ＲＥＭを０．０５質量％を超えて過剰に添加すると、熱間加工性および靭性を低下させる可能性があるとともに、加速酸化の起点となる介在物が生成しやすくなって耐高温酸化性を低下させる可能性がある。したがって、ＲＥＭを含有させる場合のＲＥＭ含有量は、０．００１質量％以上０．０５質量％以下とする。 REM has an effect of improving high-temperature oxidation resistance. In other words, REMs such as La and Ce stabilize the Al oxide film and improve the high-temperature oxidation resistance by improving the adhesion between the matrix and the oxide film. In order to achieve such an effect, REM must be added in an amount of 0.001% by mass or more. On the other hand, if REM is added in excess of 0.05% by mass, hot workability and toughness may be reduced, and inclusions serving as starting points for accelerated oxidation may be easily generated. May be reduced. Therefore, when REM is contained, the REM content is set to 0.001% by mass or more and 0.05% by mass or less.
なお、基本的にはＴｉ（チタン）は無添加であるが、Ｔｉを添加する場合には上限を０．０３質量％とする。 Basically, Ti (titanium) is not added, but when Ti is added, the upper limit is set to 0.03% by mass.
ここで、耐酸化性を向上するには、均一で層状のＡｌ系酸化物（Ａｌ２Ｏ３）を生成することが重要であり、均一で層状のＡｌ２Ｏ３を生成するには、鋼の表面にある程度の歪を付与してＣｒおよびＡｌの拡散速度を高める必要がある。すなわち、鋼の表面に歪を付与することで、加熱時に歪を駆動力としてＣｒおよびＡｌが拡散しやすく、早期に均一な層状のＡｌ２Ｏ３が生成される。 Here, in order to improve the oxidation resistance, it is important to generate Al oxide layered (Al 2 O 3) is uniform, to generate Al 2 O 3 Layered uniform, steel It is necessary to increase the diffusion rate of Cr and Al by imparting a certain degree of strain to the surface of. That is, by applying strain to the surface of the steel, Cr and Al are easily diffused by using the strain as a driving force during heating, and uniform layered Al 2 O 3 is generated at an early stage.
そして、表面に歪が付与されると鋼の表面の硬さが上昇するため、ステンレス鋼において、歪が付与されて硬化した鋼表面の硬さと鋼の板厚中央部の硬さとの差を、ＣｒおよびＡｌの拡散速度を高めるために表層に付与する歪の目安とする。 And, since the hardness of the steel surface increases when strain is applied to the surface, in stainless steel, the difference between the hardness of the steel surface where the strain is applied and hardened and the hardness of the steel thickness center portion, It is used as a measure of the strain applied to the surface layer in order to increase the diffusion rates of Cr and Al.
具体的には、鋼表面をマイクロビッカース０．１ｋｇで測定した硬さをＨＶａとし、板厚中央部をマイクロビッカース０．１ｋｇで測定した硬さをＨＶｂとすると、ＨＶａ−ＨＶｂ＜３０では、鋼の表層への歪の付与によるＣｒおよびＡｌの拡散速度の向上作用を十分に確保できない可能性がある。したがって、Ａｌ含有フェライト系ステンレス鋼では、ＨＶａ−ＨＶｂ≧３０となるように、表面に歪が付与されている。 Specifically, assuming that the hardness of the steel surface measured with 0.1 kg of micro Vickers is HVa and the hardness of the central part of the steel plate measured with 0.1 kg of micro Vickers is HVb, if HVa-HVb <30, There is a possibility that the effect of improving the diffusion rate of Cr and Al due to the application of strain to the surface layer cannot be sufficiently ensured. Therefore, in the Al-containing ferritic stainless steel, the surface is strained so that HVa−HVb ≧ 30.
なお、鋼の表面に歪を付与するには、例えば仕上研磨設備において、研磨紙（エメリー紙）♯８０〜♯１２００を用い、圧下圧力５ｋｇ／ｃｍ２以上で研磨する方法等がある。また、ショットブラストやスキンパス等でも同様に歪を付与することができる。 In order to impart strain to the surface of the steel, for example, there is a method in which polishing paper (emery paper) # 80 to # 1200 is used and polishing is performed at a rolling pressure of 5 kg / cm 2 or more in a finishing polishing facility. Also, a shot blast, a skin pass, or the like can similarly apply distortion.
また、Ｔｉを添加すると、Ｔｉを含む複合酸化物（Ｆｅ，Ｃｒ，Ｔｉ系の酸化物）が生成しやすくなり、このＴｉを含む複合酸化物によって鋼の表層におけるＡｌ２Ｏ３の均一生成が阻害されてしまい、耐高温酸化性が低下する。 Further, when Ti is added, a composite oxide containing Ti (Fe, Cr, Ti-based oxide) is easily generated, and the generation of Al 2 O 3 in the surface layer of steel is uniform by the composite oxide containing Ti. It is hindered, and the high-temperature oxidation resistance decreases.
これに対して、Ｎｂは酸化物を生成しにくいため、Ａｌ２Ｏ３の均一生成に悪影響がなく、ＣｒおよびＡｌの拡散速度も上昇させる作用も奏する。 On the other hand, since Nb hardly generates an oxide, it does not adversely affect the uniform generation of Al 2 O 3 and also has an effect of increasing the diffusion rates of Cr and Al.
そして、１０００℃で３００時間の加熱により鋼の最外層側に生成された酸化物は、表面積５ｍｍ２において、ＥＤＸ定量分析で測定したＦｅ、Ｃｒ、ＴｉおよびＮｂの合計の濃度が１０．０質量％を超えると、Ｆｅ、ＣｒおよびＴｉの酸化物によってＡｌ２Ｏ３の均一生成が阻害される可能性がある。したがって、上記Ｆｅ、Ｃｒ、ＴｉおよびＮｂの合計の濃度を１０．０質量％以下とする。 The oxide produced on the outermost layer side of the steel by heating at 1000 ° C. for 300 hours has a total concentration of 10.0 masses of Fe, Cr, Ti and Nb measured by EDX quantitative analysis at a surface area of 5 mm 2 . %, There is a possibility that the oxides of Fe, Cr and Ti may inhibit the uniform production of Al 2 O 3 . Therefore, the total concentration of Fe, Cr, Ti and Nb is set to 10.0% by mass or less.
なお、鋼の最外層側に生成された酸化物におけるＦｅ、Ｃｒ、ＴｉおよびＮｂの濃度は、酸化物としての質量ではなく、各金属単体としての質量に基づくものである。また、具体的にはＥＤＸ分析した結果であり、Ｆｅ、Ｃｒ、ＴｉおよびＮｂ以外に酸素等も含まれている。 The concentrations of Fe, Cr, Ti and Nb in the oxide formed on the outermost layer side of the steel are based on the mass of each metal alone, not the mass of the oxide. In addition, it is a result of an EDX analysis, specifically containing oxygen and the like in addition to Fe, Cr, Ti and Nb.
上記一実施の形態のＡｌ含有フェライト系ステンレス鋼によれば、上記各元素の含有量の範囲内で成分を調整しＴｉを添加せずに、Ｎｂを単独添加することにより、Ｔｉ添加鋼のようなＦｅ、ＣｒおよびＴｉを含む酸化物の生成が抑制されて、純度の高いＡｌ２Ｏ３が均一な層状に生成されやすくなるため、耐高温酸化性を向上できるとともに、Ｔｉを添加する場合に比べて高温強度も向上できる。 According to the Al-containing ferritic stainless steel of the above-described embodiment, by adjusting the components within the range of the content of each of the above-mentioned elements and adding Nb alone without adding Ti, it is possible to obtain a steel like Ti-added steel. Generation of an oxide containing Fe, Cr and Ti is suppressed, and high-purity Al 2 O 3 is easily generated in a uniform layer. Therefore, high-temperature oxidation resistance can be improved and Ti is added. The high-temperature strength can also be improved.
特に、１０００℃で３００時間の加熱により鋼の最外層側に生成された酸化物において、表面積５ｍｍ２でのＥＤＸ定量分析において測定したＦｅ、Ｃｒ、ＴｉおよびＮｂの合計の濃度を１０．０質量％以下とすることにより、純度の高いＡｌ２Ｏ３が均一な層状に生成されやすくなる。 In particular, in the oxide formed on the outermost layer side of the steel by heating at 1000 ° C. for 300 hours, the total concentration of Fe, Cr, Ti and Nb measured by EDX quantitative analysis with a surface area of 5 mm 2 was 10.0 mass % Or less, highly pure Al 2 O 3 is easily generated in a uniform layer.
また、ＨＶａ−ＨＶｂ≧３０であることにより、表面に付与された歪によってＣｒおよびＡｌの拡散速度の向上でき、Ａｌ２Ｏ３が均一な層状に生成されやすくなるため、耐高温酸化性を向上できる。 In addition, when HVa−HVb ≧ 30, the diffusion rate of Cr and Al can be improved by the strain applied to the surface, and Al 2 O 3 is easily generated in a uniform layer, so that the high-temperature oxidation resistance is improved. it can.
このように上記一実施の形態に係るＡｌ含有フェライト系ステンレス鋼は、耐高温酸化性および高温強度が良好であるため、例えば自動車排ガス部材、バーナー燃焼筒、暖房器具であるチムニー、熱電気の発熱体、燃料電池の改質器、筐体および配管等、５００℃以上で耐高温酸化性および耐Ｃｒ蒸発性が要求される用途に好適である。 As described above, the Al-containing ferritic stainless steel according to the above-described embodiment has good high-temperature oxidation resistance and high-temperature strength. It is suitable for applications requiring high-temperature oxidation resistance and Cr evaporation resistance at 500 ° C. or higher, such as a body, a reformer of a fuel cell, a casing, and piping.
以下、本実施例および比較例について説明する。 Hereinafter, this example and a comparative example will be described.
まず、表１に示す組成のステンレス鋼を製造し、仕上研磨設備において、研磨紙（エメリー紙）♯８０〜♯１２００を用い、圧下圧力５ｋｇ／ｃｍ２以上で研磨を行って鋼表面に歪を付与した。また、鋼表面に歪を付与した後、鋼表面および鋼の板厚中央部の硬さをマイクロビッカース０．１ｋｇで測定して、鋼表面の硬さと鋼の板厚中央部の硬さとの差（ΔＨＶ）を算出した。 First, a stainless steel having a composition shown in Table 1 was manufactured, and in a finish polishing facility, polishing was performed using a polishing paper (emery paper) # 80 to # 1200 at a rolling pressure of 5 kg / cm 2 or more to deform the steel surface. Granted. After applying strain to the steel surface, the hardness of the steel surface and the central part of the steel thickness was measured with a micro Vickers 0.1 kg, and the difference between the hardness of the steel surface and the hardness of the central part of the steel thickness was measured. (ΔHV) was calculated.
各鋼の組成、および、鋼表面に歪を付与した後のΔＨＶを表１に示す。なお、表１ではΔＨＶ≧３０のものを○で示し、ΔＨＶ＜３０のものを×で示す。 Table 1 shows the composition of each steel and the ΔHV after strain was applied to the steel surface. In Table 1, those with ΔHV ≧ 30 are indicated by ○, and those with ΔHV <30 are indicated by x.
これら各鋼について、１０００℃で３００時間の加熱した後、表面積５ｍｍ２においてＥＤＸ定量分析を行い、最外層側に生成された酸化物におけるＦｅ、Ｃｒ、ＴｉおよびＮｂの濃度を測定した。 After heating each of these steels at 1000 ° C. for 300 hours, EDX quantitative analysis was performed on a surface area of 5 mm 2 to measure the concentrations of Fe, Cr, Ti, and Nb in the oxide formed on the outermost layer side.
ＥＤＸ定量分析では、ＳＥＭ−ＥＤＸ装置を用い、加速電圧１５ｋＶ、電流７０〜８０μＡおよび分析時間１００秒とした。 In the EDX quantitative analysis, the acceleration voltage was 15 kV, the current was 70 to 80 μA, and the analysis time was 100 seconds using a SEM-EDX device.
このＥＤＸ定量分析による濃度の測定結果を表２に示す。なお、表２では、ＥＤＸ定量分析にて測定したＦｅ、Ｃｒ、ＴｉおよびＮｂの合計の濃度が１０質量％以下のものを○で示し、合計の濃度が１０質量％を超えたものを×で示す。 Table 2 shows the measurement results of the concentration by this EDX quantitative analysis. In Table 2, those having a total concentration of Fe, Cr, Ti, and Nb measured by EDX quantitative analysis of 10% by mass or less are indicated by ○, and those having a total concentration exceeding 10% by mass are indicated by x. Show.
また、本実施例である鋼種Ｎｏ．１およびＴｉを添加した比較例である鋼種Ｎｏ．１４の鋼表面における酸化物を観察した。鋼種Ｎｏ．１の鋼表面の酸化物の写真を図１（ａ）に示し、鋼種Ｎｏ．１４の鋼表面の酸化物の写真を図１（ｂ）に示す。 In addition, in the steel type No. No. 1 and the steel type No. Oxide on the steel surface of No. 14 was observed. Steel type No. 1 (a) shows a photograph of the oxide on the steel surface of steel No. 1; A photograph of the oxide on the steel surface of No. 14 is shown in FIG.
表１の各鋼について、高温酸化性を評価するために、１０００℃で３００時間の加熱した後の酸化増量を測定した。 For each of the steels in Table 1, in order to evaluate the high-temperature oxidation property, the oxidation increase after heating at 1000 ° C. for 300 hours was measured.
酸化増量の測定では、板厚１．０ｍｍの鋼板から、端面は切削加工を施した２５ｍｍ×３５ｍｍの試験片を作製した。その試験片をエレマ電気炉に収容した後、大気雰囲気下、炉内温度１０００℃で３００時間の連続酸化試験を実施した。そして、連続酸化試験前後における試験片の質量変化を測定し、酸化増量とした。 In the measurement of the oxidation increase, a test piece of 25 mm × 35 mm having a cut end face was prepared from a steel sheet having a thickness of 1.0 mm. After storing the test piece in an Erama electric furnace, a continuous oxidation test was performed at 1,000 ° C. for 300 hours in a furnace under an air atmosphere. And the mass change of the test piece before and after the continuous oxidation test was measured, and it was set as the oxidation increase.
この酸化増量の測定結果を表２に示す。なお、表２では、酸化増量が０．４０ｍｇ／ｃｍ２以下のものを耐高温酸化性が良好であると評価して○で示し、酸化増量が０．４０ｍｇ／ｃｍ２を超えたものを耐高温酸化性が不十分である評価して×で示す。 Table 2 shows the measurement results of the oxidation increase. In Table 2, those having an oxidation weight gain of 0.40 mg / cm 2 or less were evaluated as having good high-temperature oxidation resistance and are indicated by a circle, and those having an oxidation weight gain of more than 0.40 mg / cm 2 were evaluated. It is evaluated as insufficient in high-temperature oxidation properties and is indicated by x.
さらに、表１の各鋼について、高温強度を評価するために、７００℃での０．２％耐力を測定した。この７００℃での０．２％耐力の測定結果を表２に示す。なお、表２では、７００℃での０．２％耐力が１００ＭＰａ以上のものを高温強度が良好であると評価して○で示し、７００℃での０．２％耐力が１００ＭＰａ未満のものを高温強度が不十分であると評価して×で示す。 Further, for each steel in Table 1, the 0.2% proof stress at 700 ° C. was measured in order to evaluate the high-temperature strength. Table 2 shows the measurement results of the 0.2% proof stress at 700 ° C. In Table 2, those having a 0.2% proof stress at 700 ° C. of 100 MPa or more were evaluated as having good high-temperature strength and are indicated by “○”, and those having a 0.2% proof stress at 700 ° C. of less than 100 MPa were evaluated. The high-temperature strength was evaluated as insufficient, and is indicated by x.
また、表１の各鋼について、加工性（深絞り性）を深絞り試験装置で評価した。 Further, the workability (deep drawability) of each steel in Table 1 was evaluated by a deep draw test apparatus.
この加工性の評価では、板厚１．０ｍｍの鋼板から、ポンチ径φ４０ｍｍ／Ｒ８、ダイス径φ４２．５ｍｍ、ポンチ速度１０ｍｍ／分で絞り加工を施した。そして、試験片のブランク径をＡとし、ポンチ径をＢとし、絞り比をＣとすると、Ｃ＝Ａ／Ｂの式に基づいて絞り比を算出した。 In the evaluation of the workability, drawing was performed from a steel plate having a thickness of 1.0 mm at a punch diameter of φ40 mm / R8, a die diameter of φ42.5 mm, and a punch speed of 10 mm / min. Then, assuming that the blank diameter of the test piece is A, the punch diameter is B, and the drawing ratio is C, the drawing ratio was calculated based on the equation of C = A / B.
この絞り比の測定結果を表２に示す。なお、表２では、絞り比が２．００以上のものを加工性が良好であると評価して○で示し、絞り比が２．００未満のものを加工性が不十分であると評価して×で示す。 Table 2 shows the measurement results of the aperture ratio. In Table 2, those having a draw ratio of 2.00 or more were evaluated as having good workability and are indicated by ○, and those having a draw ratio of less than 2.00 were evaluated as having poor workability. X.
表２に示すように、本実施例である鋼種Ｎｏ．１ないし１２のいずれも、耐高温酸化性（酸化増量）、高温強度（７００℃での０．２％耐力）および加工性（深絞り性）が良好であった。また、図１（ａ）に示すように、鋼種Ｎｏ．１の鋼表面には、Ａｌ２Ｏ３が形成されていた。 As shown in Table 2, the steel type No. All of 1 to 12 were good in high-temperature oxidation resistance (increase in oxidation), high-temperature strength (0.2% proof stress at 700 ° C.), and workability (deep drawability). Further, as shown in FIG. Al 2 O 3 was formed on the steel surface of No. 1.
これに対して、比較例である鋼種Ｎｏ．１３は、Ａｌ含有量が低いため、耐高温酸化性および高温強度の目標値を満たさなかった。 On the other hand, steel type No. Sample No. 13 did not satisfy the target values of the high-temperature oxidation resistance and the high-temperature strength because the Al content was low.
比較例である鋼種Ｎｏ．１４ないし１６は、加工性の目標値を満たしているが、Ｎｂ無添加であるため、高温強度の目標値を満たさず、また、Ｔｉを添加しているため耐高温酸化性の目標値を満たさなかった。 Steel type No. which is a comparative example. Nos. 14 to 16 satisfy the target value of workability, but do not satisfy the target value of high-temperature strength because Nb is not added, and satisfy the target value of high-temperature oxidation resistance because Ti is added. Did not.
比較例である鋼種Ｎｏ．１７は、Ｎｂを添加しているため高温強度の目標値は満たすが、Ａｌ含有量が低いため耐高温酸化性の目標値を満たさなかった。 Steel type No. which is a comparative example. In No. 17, the target value of the high-temperature strength was satisfied because Nb was added, but the target value of the high-temperature oxidation resistance was not satisfied because the Al content was low.
比較例である鋼種Ｎｏ．１８は、Ｎｂ無添加であるため、高温強度の目標値を満たさなかった。 Steel type No. which is a comparative example. No. 18 did not satisfy the target value of the high-temperature strength because Nb was not added.
比較例である鋼種Ｎｏ．１９および２０は、Ａｌ含有量が高いため、加工性の目標値を満たさなかった。 Steel type No. which is a comparative example. Samples Nos. 19 and 20 did not satisfy the target value of workability due to high Al content.
比較例である鋼種Ｎｏ．２１は、Ａｌ含有量が高いため加工性の目標値を満たさず、また、Ｎｂ無添加であるため、高温強度の目標値を満たさなかった。 Steel type No. which is a comparative example. Sample No. 21 did not satisfy the target value of high temperature strength because it had a high Al content, and did not satisfy the target value of workability because Nb was not added.
比較例である鋼種Ｎｏ．２２は、ΔＨＶが３０未満で、かつ、鋼表面の酸化物におけるＦｅ、Ｃｒ、ＮｂおよびＴｉの合計濃度が１０質量％を超えているため、耐高温酸化性の目標値を満たさなかった。 Steel type No. which is a comparative example. Sample No. 22 did not satisfy the target value of high-temperature oxidation resistance because ΔHV was less than 30 and the total concentration of Fe, Cr, Nb, and Ti in the oxide on the steel surface exceeded 10% by mass.
比較例である鋼種Ｎｏ．２３は、ΔＨＶが３０以上であるが、Ｎｂが無添加でＴｉを添加しているため、耐高温酸化性および高温強度の目標値を満たさなかった。 Steel type No. which is a comparative example. Sample No. 23 had a ΔHV of 30 or more, but did not satisfy the target values of high-temperature oxidation resistance and high-temperature strength because Ti was added without adding Nb.
Claims (2)
鋼表面のマイクロビッカース０．１ｋｇで測定した硬さをＨＶａとし、鋼の厚み方向中央部のマイクロビッカース０．１ｋｇで測定した硬さをＨＶｂとすると、ＨＶａ−ＨＶｂ≧３０であり、
７００℃での０．２％耐力が１００ＭＰａ以上である
ことを特徴とするＡｌ含有フェライト系ステンレス鋼。 C: 0.025% by mass or less, Si: 0.1% by mass or less and 1.0% by mass or less, Mn: 0.8% by mass or less, P: 0.05% by mass or less, S: 0.01% by mass or less , Ni: 0.5% by mass or less, Cr: 15.0% by mass to 23.0% by mass, Al: 2.0% by mass to 4.0% by mass, N: 0.025% by mass or less, Nb : Containing not less than 0.1% by mass and not more than 0.6% by mass, with the balance being Fe and unavoidable impurities,
The hardness measured by a micro Vickers 0.1kg steel surface and HVa, when the hardness measured by a micro Vickers 0.1kg of thickness direction center portion of the steel and HVb, Ri HVa-HVb ≧ 30 der,
An Al-containing ferritic stainless steel having a 0.2% proof stress at 700 ° C. of 100 MPa or more .
ことを特徴とする請求項１記載のＡｌ含有フェライト系ステンレス鋼。 Mo: 0.05% to 0.5% by mass, V: 0.05% to 0.5% by mass, Cu: 0.05% to 0.5% by mass, Zr: 0.05 2. The composition according to claim 1, further comprising at least one of at least 0.5% by mass, at most 0.5% by mass, at least 0.005% by mass of B, and at most 0.001% by mass and at most 0.05% by mass of REM. 3. Al-containing ferritic stainless steel .
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