JP5709571B2 - High purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength and method for producing the same - Google Patents
High purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength and method for producing the same Download PDFInfo
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Description
本発明は、例えば400℃以上、1000℃以下の高温環境における耐酸化性と高温強度に優れた省合金型の高純度フェライト系ステンレス鋼板およびその製造方法に関するものである。具体的には、暖房機器,燃焼機器,自動車排気系などの部材を構成するのに好適な耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼に関する。 The present invention relates to an alloy-saving high-purity ferritic stainless steel sheet excellent in oxidation resistance and high-temperature strength in a high-temperature environment of, for example, 400 ° C. or higher and 1000 ° C. or lower, and a method for manufacturing the same. Specifically, the present invention relates to high-purity ferritic stainless steel excellent in oxidation resistance and high-temperature strength suitable for constituting members such as heating equipment, combustion equipment, and automobile exhaust systems.
フェライト系ステンレス鋼は、厨房機器、家電製品、電子機器など幅広い分野で使用されている。近年、精錬技術の向上により極低炭素・窒素化,PやSなど不純物元素の低減が可能となり、NbやTi等の安定化元素を添加して耐銹性と加工性を高めたフェライト系ステンレス鋼(以下、高純度フェライト系ステンレス鋼)は広範囲の用途へ適用されつつある。これは、高純度フェライト系ステンレス鋼が、近年価格高騰の著しいNiを多量に含有するオ−ステナイト系ステンレス鋼よりも経済性に優れているためである。 Ferritic stainless steel is used in a wide range of fields such as kitchen equipment, home appliances, and electronic equipment. Recent improvements in refining technology have enabled extremely low carbon, nitrogenization, reduction of impurity elements such as P and S, and addition of stabilizing elements such as Nb and Ti to improve ferritic stainless steel with improved weather resistance and workability Steel (hereinafter referred to as high-purity ferritic stainless steel) is being applied to a wide range of applications. This is because the high-purity ferritic stainless steel is more economical than the austenitic stainless steel containing a large amount of Ni, whose price has been increasing significantly in recent years.
耐酸化性と高温強度が要求される耐熱鋼分野においても、SUS430J1L,SUS436J1L,SUH21等の高純度フェライト系ステンレス鋼が規格化されている(JIS G 4312)。SUS430J1Lは19Cr−0.5Nb、SUS436J1Lは18Cr−1Mo、SUH21は18Cr−3Alに代表されるように、希少元素であるNbやMoの添加、あるいは多量のAl添加を特徴としている。SUH21に代表されるAl含有高純度フェライト系ステンレス鋼は、優れた耐酸化性を有しているものの、加工性や溶接性ならびに低靭性に伴う製造性に課題がある。 In the heat-resistant steel field where oxidation resistance and high-temperature strength are required, high-purity ferritic stainless steels such as SUS430J1L, SUS436J1L, and SUH21 are standardized (JIS G 4312). As represented by 19Cr-0.5Nb for SUS430J1L, 18Cr-1Mo for SUS436J1L, and 18Cr-3Al for SUH21, it is characterized by the addition of rare elements Nb and Mo, or a large amount of Al. Although Al-containing high-purity ferritic stainless steel represented by SUH21 has excellent oxidation resistance, there are problems in workability, weldability, and manufacturability associated with low toughness.
上述したAl含有高純度フェライトの課題に対して、これまで種々の検討がなされている。例えば、特許文献1には、Cr:13〜20%,Al:1.5〜2.5%未満,Si:0.3〜0.8%,Ti:3×(C+N)〜20×(C+N)を特徴とする加工性,耐酸化性に優れたAl含有耐熱フェライト系ステンレス鋼板及びその製造方法が開示されている。特許文献2には、Cr:8〜25%,C:0.03%以下,N:0.03%以下,Si:0.1〜2.5%,Al:4%以下、A=Cr+5(Si+Al)と定義されるA値が13〜60の範囲とする耐水蒸気酸化性、熱疲労特性に優れたフェライト系ステンレス鋼が開示されている。これら特許文献1,2に開示されたステンレス鋼は、Alの添加量を低くして、Siとの複合添加を特徴としている。Siも鋼の靭性を低下させる元素であることから,これら鋼の製造性に対する課題は残る。また、特許文献3に開示されたステンレス鋼は、Cr:11〜21%,Al:0.01〜0.1%,Si:0.8〜1.5%,Ti:0.05〜0.3%,Nb:0.1〜0.4%,C:0.015%以下,N:0.015%以下,必要に応じて高温強度を得るために2%以下のWを添加している。特許文献3に開示されたステンレス鋼は、Al量を低減してSiや希少元素であるWの添加により耐酸化性と高温強度を確保している。
Various studies have been made on the above-described problems of Al-containing high-purity ferrite. For example, in
上記課題を解決する手段として、高合金化に依らず、微量元素を利用して耐酸化性と高温強度を改善する方法が考えられる。従来、耐酸化性を飛躍的に向上する微量元素として、希土類元素の利用が知られている。例えば、特許文献4には、SiやAlに頼らず、Cr:12〜32%のフェライト系ステンレス鋼への希土類元素:0.2%以下、Y:0.5%以下、Hf:0.5%以下、Zr:1%以下のうち1種または2種以上、それらの合計を1%以下として添加することを開示している。また、高温強度については、特許文献5においてSn,Sbの微量元素を含む高温強度に優れたフェライト系ステンレス鋼及びその製造方法が開示されている。特許文献5に開示された大半の鋼は、Cr:10〜12%の低Cr鋼であり、Cr:12%超の高Cr鋼では高温強度を確保するためにV,Mo等を複合添加している。Sn、Sbの効果として、高温強度の改善を挙げており、本発明の目的とする耐酸化性に関わる検討や記載は見られない。 As means for solving the above problems, there is considered a method for improving oxidation resistance and high-temperature strength by using a trace element without depending on high alloying. Conventionally, the use of rare earth elements is known as a trace element that dramatically improves oxidation resistance. For example, Patent Document 4 does not rely on Si or Al, but rare earth elements to Cr: 12 to 32% ferritic stainless steel: 0.2% or less, Y: 0.5% or less, Hf: 0.5 % Or less, Zr: 1% or less of 1% or less, and adding them as 1% or less is disclosed. As for the high temperature strength, Patent Document 5 discloses a ferritic stainless steel excellent in high temperature strength containing trace elements of Sn and Sb and a method for producing the same. Most steels disclosed in Patent Document 5 are low Cr steels with Cr: 10-12%, and high Cr steels with Cr: more than 12% are combined with V, Mo, etc. in order to ensure high temperature strength. ing. As an effect of Sn and Sb, improvement of high-temperature strength is cited, and no examination or description relating to the oxidation resistance targeted by the present invention is found.
これまで発明者らは、省資源・経済性の観点から,CrやMoの高合金化によらず,Snの微量添加により耐食性や加工性を改善した高純度フェライト系ステンレス鋼について開示している。特許文献6および7に開示したステンレス鋼は、Cr:13〜22%,Sn:0.001〜1%でC,N,Si,Mn,Pを低減し、Al:0.005〜0.05%の範囲とし、必要に応じてTiやNbの安定化元素を添加した高純度フェライト系ステンレス鋼である。
しかしながら、これらの特許文献には、本発明の目的とする耐酸化性や高温強度に対する微量のSnとAl添加の影響については何ら検討されていない。
また、特許文献8には、Cr:11〜22%、Al:1.0〜6.0%を含有し、C,N,Sを低減し、Sn:0.001〜1.0%,Nb:0.001〜0.70%、V:0.001〜0.50%よりなる群より選ばれる1種以上の元素を含有するフェライト系ステンレス鋼が開示されており、高温水蒸気に曝される環境下におけるCr及び/又はその化合物の蒸発防止については開示されているが、耐酸化性、高温強度に対するAl,Snの添加の効果は開示されていない。
So far, the inventors have disclosed a high-purity ferritic stainless steel that has improved corrosion resistance and workability by adding a small amount of Sn, regardless of the high alloying of Cr and Mo, from the viewpoint of resource saving and economy. . The stainless steels disclosed in Patent Documents 6 and 7 reduce C, N, Si, Mn, and P with Cr: 13-22%, Sn: 0.001-1%, and Al: 0.005-0.05. % High purity ferritic stainless steel to which a stabilizing element of Ti or Nb is added as necessary.
However, these patent documents do not discuss the influence of a small amount of Sn and Al addition on the oxidation resistance and high temperature strength which are the object of the present invention.
Patent Document 8 contains Cr: 11-22%, Al: 1.0-6.0%, reduces C, N, S, Sn: 0.001-1.0%, Nb : Ferritic stainless steel containing one or more elements selected from the group consisting of 0.001 to 0.70% and V: 0.001 to 0.50% is disclosed and is exposed to high-temperature steam Although prevention of evaporation of Cr and / or its compounds in the environment is disclosed, the effects of addition of Al and Sn on oxidation resistance and high temperature strength are not disclosed.
上述した通り、高純度フェライト系ステンレス鋼において、耐酸化性と高温強度を確保するにはAlの添加、あるいはAlとSiの複合添加が有効であるものの、製造性や溶接性に課題が残る。また,AlやSiの高合金化に依らず上記の特性を確保するには、Nb,Mo,Wや希土類など大変高価な希少元素を利用する必要がある。他方,省資源・経済性の観点から微量Snを添加した高純度フェライト系ステンレス鋼も開示されているが、耐酸化性と高温強度を具備するには至っていない。
そこで本発明の目的は、製造性や溶接性を阻害するAlやSiの過度の合金化やNb,Mo,W,希土類等の希少元素の添加に頼ることなく、Sn添加を活用して耐酸化性と高温強度を向上させた省合金型の高純度フェライト系ステンレス鋼板とその製造方法を提供することにある。
As described above, in high-purity ferritic stainless steel, although addition of Al or combined addition of Al and Si is effective to ensure oxidation resistance and high-temperature strength, problems remain in manufacturability and weldability. Also, in order to ensure the above characteristics regardless of the high alloying of Al or Si, it is necessary to use very expensive rare elements such as Nb, Mo, W and rare earth. On the other hand, high-purity ferritic stainless steel added with a small amount of Sn is also disclosed from the viewpoint of resource saving and economical efficiency, but has not yet achieved oxidation resistance and high-temperature strength.
Therefore, the object of the present invention is to utilize Sn addition to prevent oxidation without relying on excessive alloying of Al or Si, which impedes manufacturability and weldability, or addition of rare elements such as Nb, Mo, W, and rare earths. It is an object of the present invention to provide an alloy-saving high-purity ferritic stainless steel sheet with improved properties and high-temperature strength and a method for producing the same.
本発明者らは、前記した課題を解決するために、高純度フェライト系ステンレス鋼において、Sn添加とAlの作用に着目して耐酸化性と高温強度に対する効果について鋭意研究を行い,下記の新しい知見を得て本発明をなすに至った。 In order to solve the above-mentioned problems, the present inventors have conducted intensive research on the effect on oxidation resistance and high-temperature strength, focusing on the addition of Sn and the action of Al in high-purity ferritic stainless steel. Knowledge has been obtained and the present invention has been made.
(a)Snは高温強度の上昇に有効な元素であり、Snを添加することでNb,Mo,Wの添加を削減することが出来る。Sn添加により高温強度に加えて、耐酸化性の向上効果を発現させるには16%以上のCr量が有効であることを見出した。このような耐酸化性の向上作用については未だ不明なところも多いものの、以下に述べるような実験事実に基づいて、その作用機構を推察している。 (A) Sn is an element effective for increasing the high-temperature strength, and the addition of Nb, Mo, and W can be reduced by adding Sn. It has been found that a Cr amount of 16% or more is effective for exhibiting the effect of improving the oxidation resistance in addition to the high temperature strength by the addition of Sn. Although there are many unclear points about such an effect of improving oxidation resistance, the mechanism of its action is presumed based on experimental facts as described below.
(b)Sn添加した16Cr鋼(以下、Sn添加16Cr鋼)と段落〔0003〕で述べた耐熱ステンレス鋼:19Cr−0.5Nb鋼、18Cr−1Mo鋼を950℃,200hrの大気中連続酸化試験を行った。19Cr−0.5Nb鋼や18Cr−1Mo鋼では酸化皮膜の剥離が進行し始めるのに対して、Sn添加16Cr鋼は、異常酸化や酸化皮膜の剥離を生じることなく、高い保護性皮膜の安定性を示した。 (B) Sn-added 16Cr steel (hereinafter referred to as Sn-added 16Cr steel) and heat-resistant stainless steel described in paragraph [0003]: 19Cr-0.5Nb steel and 18Cr-1Mo steel in an atmospheric continuous oxidation test at 950 ° C. and 200 hr. Went. In 19Cr-0.5Nb steel and 18Cr-1Mo steel, the peeling of the oxide film begins to progress, whereas in the case of Sn-added 16Cr steel, the stability of the high protective film is eliminated without causing abnormal oxidation or peeling of the oxide film. showed that.
(c)Sn添加16Cr鋼において酸化皮膜の詳細な分析から、Snは酸化皮膜中に存在せず、酸化皮膜のCr濃度は19Cr−0.5Nb鋼や18Cr−1Mo鋼よりも高いことが判明した。すなわち、Sn添加は、クロミヤ皮膜(Cr2O3)中のCr濃度を高めて、Cr2O3の破壊に繋がるFe,Mn,Ti等の酸化皮膜中への侵入を抑制する作用を示した。このようなSn添加の効果により、前記した耐熱ステンレス鋼:19Cr−0.5Nb鋼、18Cr−1Mo鋼と同等以上の耐酸化性と高温強度を省合金型の16Cr鋼で達成することが出来る。 (C) Detailed analysis of the oxide film in Sn-added 16Cr steel revealed that Sn was not present in the oxide film, and the Cr concentration of the oxide film was higher than that of 19Cr-0.5Nb steel or 18Cr-1Mo steel. . That is, the addition of Sn showed an action of increasing the Cr concentration in the chromia coating (Cr 2 O 3 ) and suppressing the penetration of Fe, Mn, Ti, etc. into the oxide coating that leads to the destruction of Cr 2 O 3 . . Due to the effect of such Sn addition, oxidation resistance and high temperature strength equal to or higher than those of the above heat resistant stainless steels: 19Cr-0.5Nb steel and 18Cr-1Mo steel can be achieved with the alloy-saving 16Cr steel.
(d)前記したSn添加16Cr鋼の耐酸化性は、Alを0.05%以上添加することで安定的に発現することを見出した。Al量が0.8%以下の場合、Alの連続酸化皮膜は生成しないものの、鋼界面の酸素分圧を低下してCr2O3の安定性向上に寄与しているものと考えられる。このようなSn+Alによる耐酸化性向上については未だ不明なところも多いものの,Sn添加の効果が微量のAl量で重畳していると思われる。 (D) It has been found that the oxidation resistance of the above-described Sn-added 16Cr steel is stably expressed by adding 0.05% or more of Al. When the amount of Al is 0.8% or less, although a continuous oxide film of Al is not generated, it is considered that the oxygen partial pressure at the steel interface is lowered to contribute to the improvement of the stability of Cr 2 O 3 . Although there are still many unclear points about such oxidation resistance improvement by Sn + Al, it seems that the effect of Sn addition is superimposed on a small amount of Al.
(e)上述した耐酸化性の向上には、C、N、P、Sの低減により鋼の高純度化を図り、NbやTiの安定化元素を添加することが効果的である。 (E) In order to improve the oxidation resistance described above, it is effective to increase the purity of steel by reducing C, N, P, and S, and to add a stabilizing element such as Nb or Ti.
(f)熱間圧延時の鋳片の加熱において加熱後の抽出温度は、ヘゲ疵や表面性状を阻害する鋳片表層の介在物を除去するためのスケール生成量を確保し、微細なTiCSを生成して異常酸化を誘発する固溶Sを低減し、異常酸化の起点となりうるMnSやCaSの生成を抑制する温度とする。Cr量16%以上のSn添加鋼では1100〜1200℃とすることが効果的である。 (F) In the heating of the slab during hot rolling, the extraction temperature after heating secures the amount of scale generated for removing the haze and the inclusions on the surface of the slab that obstruct the surface properties, and the fine TiCS Is reduced to solid solution S that induces abnormal oxidation, and the temperature is set to suppress the generation of MnS and CaS that can be the starting point of abnormal oxidation. For Sn-added steel with a Cr content of 16% or more, it is effective to set the temperature to 1100 to 1200 ° C.
(g)熱間圧延後の巻取りは、鋼靭性を確保し、表面性状の低下を招く内部酸化物や粒界酸化を抑制する温度とする。Cr量16%以上のSn添加鋼では500〜600℃とすることが有効である。また、熱延板焼鈍を900℃以上で実施してNbやTi等の安定化元素を固溶させ,550〜850℃の温度域を10℃/秒以下で徐冷することは、SnやCrの粒界偏析の低減と微細な炭窒化物生成を促進して、高温強度と耐酸化性を高めることに有効である。 (G) The coiling after hot rolling is performed at a temperature that ensures steel toughness and suppresses internal oxides and grain boundary oxidation that cause deterioration of surface properties. For Sn-added steel with a Cr content of 16% or more, it is effective to set the temperature to 500 to 600 ° C. Moreover, it is Sn or Cr to carry out hot-rolled sheet annealing at 900 ° C. or more to dissolve a stabilizing element such as Nb or Ti and to gradually cool a temperature range of 550 to 850 ° C. at 10 ° C./second or less It is effective in enhancing the high temperature strength and oxidation resistance by promoting the reduction of grain boundary segregation and the formation of fine carbonitrides.
上記(a)〜(g)の知見に基づいて成された本発明の要旨は、以下の通りである。 The gist of the present invention based on the findings (a) to (g) is as follows.
(1)質量%にて、C:0.001〜0.03%、Si:0.01〜2%、Mn:0.01〜1.5%、P:0.005〜0.05%、S:0.0001〜0.01%、Cr:16〜30%、N:0.001〜0.03%、Al:0.05〜0.8%、Sn:0.01〜1%、残部がFeおよび不可避的不純物からなり、
800℃での0.2%耐力が35MPa以上であって、引張強さが55MPa以上であることを特徴とする耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板。
(2)前記鋼が、質量%にて、C:0.004〜0.03%であることを特徴とする(1)に記載の耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板。
(3)前記鋼が、質量%にて、Sn:0.01〜0.29%及びCr:16〜18.8%であることを特徴とする(1)又は(2)に記載の耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板。
(1) In mass%, C: 0.001 to 0.03%, Si: 0.01 to 2%, Mn: 0.01 to 1.5%, P: 0.005 to 0.05%, S: 0.0001 to 0.01%, Cr: 16 to 30%, N: 0.001 to 0.03%, Al: 0.05 to 0.8%, Sn: 0.01 to 1%, balance Ri but Do of Fe and unavoidable impurities,
A 800 0.2% yield strength of at ℃ is 35MPa or more, tensile strength of the high-purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength, characterized in der Rukoto least 55 MPa.
(2) The high purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength according to (1), wherein the steel is C: 0.004 to 0.03% in mass%. .
(3) The oxidation resistance according to (1) or (2), wherein the steel is Sn: 0.01 to 0.29% and Cr: 16 to 18.8% in mass%. High-purity ferritic stainless steel sheet with excellent strength and high-temperature strength.
(4)前記鋼が、さらに質量%にて、Nb:0.5%以下、Ti:0.5%以下、Ni:0.5%以下、Cu:0.5%以下、Mo:0.5%以下、V:0.5%以下、Zr:0.5%以下、Co:0.5%以下、Mg:0.005%以下、B:0.005%以下、Ca:0.005%以下の1種または2種以上含有していることを特徴とする(1)から(3)のいずれかに記載の耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板。 ( 4 ) The steel is further mass%, Nb: 0.5% or less, Ti: 0.5% or less, Ni: 0.5% or less, Cu: 0.5% or less, Mo: 0.5 % Or less, V: 0.5% or less, Zr: 0.5% or less, Co: 0.5% or less, Mg: 0.005% or less, B: 0.005% or less, Ca: 0.005% or less The high purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength according to any one of (1) to (3), characterized in that one or more of
(5)前記鋼が、さらに質量%にて、La:0.1%以下,Y:0.1%以下,Hf:0.1%以下,REM:0.1%以下の1種または2種以上含有していることを特徴とする(1)から(4)のいずれかに記載の耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板。 ( 5 ) One or two of the above steels in terms of mass%: La : 0.1% or less, Y: 0.1% or less, Hf: 0.1% or less, REM: 0.1% or less The high purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength according to any one of (1) to (4), characterized in that it is contained above.
(6)(1)〜(5)のいずれかに記載の鋼成分を有するステンレス鋼スラブを加熱して抽出温度を1100〜1250℃とし、熱間圧延終了後の巻取り温度を600℃以下とすることを特徴とする(1)〜(5)のいずれかに記載の耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板の製造方法。 ( 6 ) The stainless steel slab having the steel component according to any one of (1) to ( 5 ) is heated to an extraction temperature of 1100 to 1250 ° C, and a winding temperature after the hot rolling is 600 ° C or less. The manufacturing method of the high purity ferritic stainless steel plate excellent in oxidation resistance and high temperature strength in any one of (1)-( 5 ) characterized by performing.
(7)(6)に記載した製造方法によって製造した(1)〜(5)のいずれかに記載の鋼成分を有する熱延鋼板を900〜1050℃で焼鈍した後、550〜850℃の温度域を10℃/秒以下で冷却することを特徴とするとする(1)〜(5)のいずれかに記載の耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板の製造方法。 ( 7 ) After annealing the hot-rolled steel sheet having the steel component according to any one of (1) to ( 5 ) manufactured by the manufacturing method described in ( 6 ) at 900 to 1050 ° C, a temperature of 550 to 850 ° C The method for producing a high-purity ferritic stainless steel sheet excellent in oxidation resistance and high-temperature strength according to any one of (1) to ( 5 ), wherein the region is cooled at 10 ° C./second or less.
本発明によれば、製造性や溶接性を阻害するAlやSiの過度の合金化やNb,Mo,W,希土類等の希少元素の添加に頼ることなく、Sn添加を活用して耐酸化性と高温強度を既存耐熱鋼と同等以上に向上した省合金型の高純度フェライト系ステンレス鋼板を得ることができるという顕著な効果を奏するものである。 According to the present invention, oxidation resistance is obtained by utilizing Sn addition without resorting to excessive alloying of Al or Si, which impairs manufacturability and weldability, or addition of rare elements such as Nb, Mo, W, and rare earths. In addition, it is possible to obtain an alloy-saving type high-purity ferritic stainless steel sheet having a high temperature strength that is equal to or higher than that of existing heat-resistant steel.
以下、本発明の各要件について詳しく説明する。なお、各元素の含有量の「%」表示は「質量%」を意味する。 Hereinafter, each requirement of the present invention will be described in detail. In addition, "%" display of the content of each element means "mass%".
(I)まず、鋼板の成分の限定理由を以下に説明する。
Cは、耐酸化性を劣化させるので、その含有量は少ないほど良いため、上限を0.03%とする。但し、過度の低減は精錬コストの増加に繋がるため、下限を0.001%とする。好ましくは、耐酸性や製造コストを考慮して0.002〜0.01%とする。
(I) First, the reasons for limiting the components of the steel sheet will be described below.
Since C deteriorates the oxidation resistance, the lower the content, the better. Therefore, the upper limit is made 0.03%. However, excessive reduction leads to an increase in refining costs, so the lower limit is made 0.001%. Preferably, it is 0.002 to 0.01% in consideration of acid resistance and manufacturing cost.
Siは、脱酸元素として有効であることに加え、耐酸化性を向上させる元素である。脱酸剤と本発明の耐酸化性を確保するために下限を0.01%とする。
但し、過度な添加は鋼靭性や加工性の低下を招くため、上限を2%とする。好ましくは効果と製造性を考慮して0.05〜1%とする。より好ましい範囲は0.1〜0.6%である。
In addition to being effective as a deoxidizing element, Si is an element that improves oxidation resistance. In order to ensure the oxidation resistance of the deoxidizer and the present invention, the lower limit is made 0.01%.
However, excessive addition causes a decrease in steel toughness and workability, so the upper limit is made 2%. Preferably, considering the effect and manufacturability, 0.05 to 1%. A more preferable range is 0.1 to 0.6%.
Mnは、耐酸化性を阻害する元素であるため、その含有量は少ないほど良い。耐酸化性の低下を抑制する観点から上限を1.5%とする。但し、過度の低減は精錬コストの増加に繋がるため、下限を0.01%とする。好ましくは、耐酸化性と製造コストを考慮して0.05〜0.5%とする。 Since Mn is an element that inhibits oxidation resistance, the smaller the content, the better. The upper limit is made 1.5% from the viewpoint of suppressing the decrease in oxidation resistance. However, excessive reduction leads to an increase in refining costs, so the lower limit is made 0.01%. Preferably, considering the oxidation resistance and the manufacturing cost, the content is made 0.05 to 0.5%.
Pは、製造性や溶接性を阻害する元素であるため、その含有量は少ないほど良い。製造性や溶接性の低下を抑制する観点から上限を0.05%とする。但し、過度の低減は精錬コストの増加に繋がるため、下限を0.005%とする。好ましくは、製造コストを考慮して0.01〜0.04%とする。 Since P is an element that impairs manufacturability and weldability, the smaller the content, the better. The upper limit is made 0.05% from the viewpoint of suppressing manufacturability and weldability deterioration. However, excessive reduction leads to an increase in refining costs, so the lower limit is made 0.005%. Preferably, considering the manufacturing cost, the content is made 0.01 to 0.04%.
Sは、耐酸化性や熱間加工性を劣化させるため、その含有量は少ないほど良い。そのため、上限は0.01%とする。但し、過度の低減は精錬コストの増加に繋がるため、下限を0.0001とする。好ましくは、耐酸化性や製造コストを考慮して0.0002〜0.002%とする。 Since S degrades oxidation resistance and hot workability, the smaller the content, the better. Therefore, the upper limit is made 0.01%. However, excessive reduction leads to an increase in refining costs, so the lower limit is made 0.0001. Preferably, considering the oxidation resistance and manufacturing cost, the content is made 0.0002 to 0.002%.
Crは、本発明の高純度フェライト系ステンレス鋼の構成元素であり、Sn添加により本発明の目標とする耐酸化性と高温強度を確保するために必須の元素である。本発明の耐酸化性と高温強度を確保するために下限は16%とする。上限は、製造性の観点から30%とする。但し、SUS430J1L、SUS436J1Lなどと比較した経済性から、好ましくは16〜22%とする。性能と合金コストを考慮して、より好ましくは、16〜18%とする。 Cr is a constituent element of the high purity ferritic stainless steel of the present invention, and is an essential element for ensuring the oxidation resistance and high temperature strength targeted by the present invention by adding Sn. In order to ensure the oxidation resistance and high temperature strength of the present invention, the lower limit is made 16%. The upper limit is 30% from the viewpoint of manufacturability. However, from the economical efficiency compared with SUS430J1L, SUS436J1L, etc., it is preferably 16 to 22%. In consideration of performance and alloy cost, it is more preferably 16 to 18%.
Nは、Cと同様に耐酸性を劣化させるので、その含有量は少ないほど良いため、上限を0.03%とする。但し、過度の低減は精錬コストの増加に繋がるため、下限を0.001%とする。好ましくは、耐酸化性や製造コストを考慮して0.005〜0.015%とする。 N, like C, degrades the acid resistance, so the lower the content, the better. Therefore, the upper limit is made 0.03%. However, excessive reduction leads to an increase in refining costs, so the lower limit is made 0.001%. Preferably, it is 0.005 to 0.015% in consideration of oxidation resistance and manufacturing cost.
Alは、脱酸元素として有効な元素であることに加え、本発明の目標とする耐酸化性を高めるために必須の元素である。下限は、Sn添加と重畳して耐酸化性の向上効果を得るために0.05%とする。上限は、製造性の観点から0.8%とする。なお、SUS430J1L、SUS436J1Lと比較した経済性から、より好ましくは0.06〜0.6%とする。 In addition to being an effective element as a deoxidizing element, Al is an essential element for enhancing the target oxidation resistance of the present invention. The lower limit is set to 0.05% in order to obtain an effect of improving oxidation resistance in combination with Sn addition. The upper limit is made 0.8% from the viewpoint of manufacturability. In addition, from the economical efficiency compared with SUS430J1L and SUS436J1L, More preferably, it is 0.06 to 0.6%.
Snは、AlやSiの過度の合金化やNb,Mo,W,希土類等の希少元素の添加に頼ることなく、本発明の目標とする耐酸化性と高温強度を確保するために必須の元素である。本発明の目標とする耐酸化性と高温強度を得るために、下限は0.01%とする。上限は、製造性の観点から1%とする。但し、SUS430J1L、SUS436J1Lなどと比較した経済性から、好ましくは0.1〜0.6%とする。性能と合金コストを考慮して、より好ましくは、0.2〜0.5%とする。 Sn is an essential element for ensuring the target oxidation resistance and high-temperature strength of the present invention without resorting to excessive alloying of Al or Si and addition of rare elements such as Nb, Mo, W, and rare earths. It is. In order to obtain the target oxidation resistance and high temperature strength of the present invention, the lower limit is made 0.01%. The upper limit is 1% from the viewpoint of manufacturability. However, from the economical efficiency compared with SUS430J1L, SUS436J1L, etc., it is preferably 0.1 to 0.6%. In consideration of performance and alloy cost, it is more preferably 0.2 to 0.5%.
Nb、Tiは、C,Nを固定する安定化元素の作用により、耐酸化性を向上させる元素であり必要に応じて添加する。添加する場合は、それぞれその効果が発現する0.03%以上とする。但し、過度な添加は合金コストの上昇や再結晶温度上昇に伴う製造性の低下に繋がるため、上限をそれぞれ0.5%とする。好ましい範囲は、効果と合金コストおよび製造性を考慮して、Nb、Tiの1種または2種で0.05〜0.5%とする。より好ましい範囲は0.1〜0.3%である。 Nb and Ti are elements that improve oxidation resistance by the action of a stabilizing element that fixes C and N, and are added as necessary. When added, the content is set to 0.03% or more where the effect is exhibited. However, excessive addition leads to a decrease in manufacturability accompanying an increase in alloy costs and a recrystallization temperature, so the upper limit is made 0.5%. A preferable range is 0.05 to 0.5% for one or two of Nb and Ti in consideration of effects, alloy costs, and manufacturability. A more preferable range is 0.1 to 0.3%.
Ni、Cu、Mo、V、Zr、Coは、Snとの相乗効果により高温強度の上昇に有効な元素であり、必要に応じて添加する。Ni、Cu、Moは、添加する場合、それぞれその効果が発現する0.15%以上とする。V、Zr、Coは、添加する場合、それぞれその効果が発現する0.01%以上とする。但し、過度な添加は合金コストの上昇や製造性の低下に繋がるため、上限をいずれも0.5%とする。 Ni, Cu, Mo, V, Zr, and Co are effective elements for increasing the high-temperature strength due to a synergistic effect with Sn, and are added as necessary. When Ni, Cu, and Mo are added, the effect is 0.15% or more. When V, Zr, and Co are added, they are set to 0.01% or more at which the effect is exhibited. However, excessive addition leads to an increase in alloy costs and a decrease in manufacturability, so the upper limit is 0.5% for both.
Mgは、溶鋼中でAlとともにMg酸化物を形成し脱酸剤として作用するほか、TiNの晶出核として作用する。TiNは凝固過程においてフェライト相の凝固核となり、TiNの晶出を促進させることで、凝固時にフェライト相を微細生成させることができる。凝固組織を微細化させることにより、製品のリジングやロ−ピングなどの粗大凝固組織に起因した表面欠陥を防止できるほか、加工性の向上をもたらすため、必要に応じて添加する。添加する場合は、これらの効果を発現する0.0001%とする。但し、0.005%を超えると製造性が劣化するため、上限を0.005%とする。好ましくは、製造性を考慮して0.0003〜0.002%とする。 Mg forms Mg oxide together with Al in molten steel and acts as a deoxidizer, and also acts as a crystallization nucleus of TiN. TiN becomes a solidification nucleus of the ferrite phase in the solidification process, and by facilitating crystallization of TiN, the ferrite phase can be finely formed during solidification. By making the solidified structure finer, it is possible to prevent surface defects caused by coarse solidified structures such as ridging and roping of products, and to improve workability. When adding, it is made 0.0001% to express these effects. However, if it exceeds 0.005%, manufacturability deteriorates, so the upper limit is made 0.005%. Preferably, considering the manufacturability, the content is made 0.0003 to 0.002%.
Bは、熱間加工性や2次加工性を向上させる元素であり、高純度フェライト系ステンレス鋼への添加は有効である。添加する場合は、これらの効果を発現する0.0003%以上とする。しかし、過度の添加は、伸びの低下をもたらすため、上限を0.005%とする。好ましくは、材料コストや加工性を考慮して0.0005〜0.002%とする。 B is an element that improves hot workability and secondary workability, and addition to high purity ferritic stainless steel is effective. When adding, it is made 0.0003% or more which expresses these effects. However, excessive addition causes a decrease in elongation, so the upper limit is made 0.005%. Preferably, considering the material cost and workability, the content is made 0.0005 to 0.002%.
Caは、熱間加工性や鋼の清浄度を向上させる元素であり、必要に応じて添加する。添加する場合は、これらの効果を発現する0.0003%以上とする。しかし、過度の添加は、製造性の低下やCaSなどの水溶性介在物による耐酸化の低下に繋がるため、上限を0.005%とする。好ましくは、製造性や耐酸化性を考慮して0.0003〜0.0015%とする。 Ca is an element that improves hot workability and steel cleanliness, and is added as necessary. When adding, it is made 0.0003% or more which expresses these effects. However, excessive addition leads to a decrease in productivity and a decrease in oxidation resistance due to water-soluble inclusions such as CaS, so the upper limit is made 0.005%. Preferably, considering the manufacturability and oxidation resistance, the content is made 0.0003 to 0.0015%.
Zr、La、Y、Hf、REMは、熱間加工性や鋼の清浄度を向上させ、耐酸化性や熱間加工性を著しく向上させる効果を持つため、必要に応じて添加しても良い。添加する場合は、それぞれその効果が発現する0.001%以上とする。しかし、過度の添加は、合金コストの上昇と製造性の低下に繋がるため、上限をそれぞれ0.1%とする。好ましくは、効果と経済性および製造性を考慮して、1種または2種以上とし、それぞれ0.001〜0.05%とする。 Zr, La, Y, Hf, and REM have the effects of improving hot workability and steel cleanliness and remarkably improving oxidation resistance and hot workability, and may be added as necessary. . When added, the content is set to 0.001% or more where the effect is exhibited. However, excessive addition leads to an increase in alloy cost and a decrease in manufacturability, so the upper limit is made 0.1%. Preferably, considering the effect, economy and manufacturability, it is 1 type or 2 types or more, and 0.001 to 0.05% respectively.
(II)次に、鋼板の好ましい製造方法に関する限定理由を以下に説明する。
前記(I)項に記載の成分を有し、SUS430J1L、SUS436J1Lと同等以上の耐酸化性と高温強度を得るために好ましい製造方法を述べたものである。
なお、本発明の鋼板は、(I)の成分組成を有する鋼を、転炉、電気炉、或はさらに二次精錬装置を用いて定法により溶製し、連続鋳造法あるいは鋼塊法によりスラブ(鋳片、鋼片)とし、このスラブを加熱炉にて加熱後、熱間圧延して熱間圧延鋼板としてコイルに巻取り、熱間圧延鋼板とするか、或は、必要により熱延板焼鈍を施したあと、さらに冷間圧延、焼鈍、酸洗処理を施して冷間圧延鋼板とするものである。
(II) Next, the reason for limitation regarding the preferable manufacturing method of a steel plate is demonstrated below.
A preferred production method is described in order to obtain the oxidation resistance and high-temperature strength equal to or higher than those of SUS430J1L and SUS436J1L having the components described in the above item (I).
The steel sheet of the present invention is a steel having the component composition (I) melted by a conventional method using a converter, an electric furnace, or a secondary refining device, and slab by a continuous casting method or a steel ingot method. (Slabs, steel slabs) After this slab is heated in a heating furnace, it is hot-rolled and wound into a coil as a hot-rolled steel sheet to form a hot-rolled steel sheet, or hot-rolled sheet if necessary After annealing, it is further subjected to cold rolling, annealing, and pickling treatment to form a cold rolled steel sheet.
熱間圧延において鋳片(スラブ)加熱後の抽出温度を1100℃以上とするのは、ヘゲ疵を誘発する鋳片表層の介在物を除するためのスケール生成量を確保するためである。スケール生成量はスケール厚さ0.1mm以上である。抽出温度の上限を1250℃とするのは、異常酸化起点となるMnSやCaSの生成を抑止してTiCSを安定化させるためである。本発明の目標とする耐酸化性を考慮して、抽出温度は1100〜1200℃とすることが好ましい。 The reason why the extraction temperature after heating the slab (slab) in hot rolling is 1100 ° C. or more is to secure a scale generation amount for removing inclusions on the surface of the slab that induces scab. The scale generation amount is a scale thickness of 0.1 mm or more. The upper limit of the extraction temperature is set to 1250 ° C. in order to stabilize TiCS by suppressing the generation of MnS and CaS that are abnormal oxidation starting points. Considering the target oxidation resistance of the present invention, the extraction temperature is preferably 1100 to 1200 ° C.
熱間圧延後の巻取り温度を600℃以下とするのは、鋼靭性を確保し、表面性状の低下を招く内部酸化物や粒界酸化を抑制するためである。また、600℃超ではTiやPを含む析出物が析出しやすく、耐酸化性の低下に繋がる恐れもある。巻取り温度を400℃未満とすると、熱間圧延後の注水により熱延鋼帯の形状不良を招き、コイル展開や通板時に表面疵を誘発する恐れがある。本発明の目標とする耐酸化性を考慮して、巻取り温度は500〜600℃とすることが好ましい。 The reason for setting the coiling temperature after hot rolling to 600 ° C. or lower is to ensure steel toughness and to suppress internal oxides and grain boundary oxidation that cause deterioration of surface properties. Moreover, when it exceeds 600 degreeC, the precipitate containing Ti and P tends to precipitate, and there exists a possibility of leading to a fall of oxidation resistance. If the coiling temperature is less than 400 ° C., water injection after hot rolling may cause defective shape of the hot-rolled steel strip, and may induce surface flaws when the coil is unfolded or passed. In consideration of the target oxidation resistance of the present invention, the winding temperature is preferably 500 to 600 ° C.
熱間圧延後、熱延板焼鈍を省略して1回の冷間圧延または中間焼鈍を挟む2回以上の冷間圧延を実施しても良い。但し、Sn、Crに加えて、NbやTiあるいはNi、Cu、Moの固溶強化により本発明の目標とする高温強度を上昇させるために900℃以上の熱延板焼鈍を行うことが好ましい。熱延板焼鈍温度の上限は、表面性状と酸洗脱スケール性の低下を考慮して、1050℃とすることが好ましい。 After the hot rolling, the hot-rolled sheet annealing may be omitted, and one cold rolling or two or more cold rolling sandwiching the intermediate annealing may be performed. However, in addition to Sn and Cr, it is preferable to perform hot-rolled sheet annealing at 900 ° C. or higher in order to increase the high-temperature strength targeted by the present invention by solid solution strengthening of Nb, Ti, Ni, Cu, or Mo. The upper limit of the hot-rolled sheet annealing temperature is preferably set to 1050 ° C. in consideration of the decrease in surface properties and pickling descaling properties.
熱延板の冷却速度は、550〜850℃の温度域において10℃/秒以下とすることは、SnやCrの粒界偏析を低減して固溶均一化を図り、微細な炭窒化物生成を促進して、高温強度と耐酸化性の向上に有効である。冷却速度は、微細析出を促進するために5℃/秒以下とすることが好ましい。下限は特に規定するものではないが、炭窒化物の粗大化を抑制するために0.01℃/秒とする。 When the cooling rate of the hot-rolled sheet is set to 10 ° C./second or less in the temperature range of 550 to 850 ° C., the grain boundary segregation of Sn and Cr is reduced, so that the solid solution is made uniform, and fine carbonitride generation Is effective in improving high temperature strength and oxidation resistance. The cooling rate is preferably 5 ° C./second or less in order to promote fine precipitation. The lower limit is not particularly specified, but is 0.01 ° C./second in order to suppress coarsening of the carbonitride.
冷間圧延の条件は特に規定するものではない。冷間圧延後の仕上げ焼鈍は、表面性状を考慮して、1000℃以下とすることが好ましい。下限は、本発明の鋼板では再結晶が完了する800℃とすることが好ましい。酸洗方法は特に規定するものではなく,工業的に常用されている方法で実施するものとする。例えば、アルカリソルトバス浸漬+電解酸洗+硝弗酸浸漬、電解酸洗は中性塩電解や硝酸電解等を行うものとする。 The conditions for cold rolling are not particularly specified. The finish annealing after cold rolling is preferably set to 1000 ° C. or less in consideration of the surface properties. The lower limit is preferably set to 800 ° C. at which recrystallization is completed in the steel sheet of the present invention. The pickling method is not particularly specified, and it should be carried out by a method commonly used in industry. For example, alkaline salt bath immersion + electrolytic pickling + nitric hydrofluoric acid immersion and electrolytic pickling are performed by neutral salt electrolysis or nitric acid electrolysis.
以下、本発明の実施例を説明する。 Examples of the present invention will be described below.
表1の成分を有するフェライト系ステンレス鋼を溶製し、加熱炉からの抽出温度1100〜1250℃で熱間圧延を行い,巻取り温度500〜720℃で板厚3.0〜6.0mmの熱延鋼板とした。熱延鋼板は焼鈍を実施して、1回または中間焼鈍を挟む2回の冷間圧延を行い、1.0〜2.0mm厚の冷延鋼板を製造した。得られた冷延鋼板は、いずれも再結晶が完了する温度850〜1050℃で仕上げ焼鈍を行った。
鋼の成分は、本発明で規定する範囲(本発明成分)とそれ以外の範囲(比較成分)でも実施した。製造条件は、本発明で限定する好ましい条件(本発明例)とそれ以外の条件(比較例)でも実施した。参考例として、市販のSUS430J1L(19%Cr−0.5%Nb鋼)とSUS436J1L(18Cr−1Mo鋼)を使用した。
A ferritic stainless steel having the components shown in Table 1 is melted and hot rolled at an extraction temperature from a heating furnace of 1100 to 1250 ° C., and a sheet thickness of 3.0 to 6.0 mm at a winding temperature of 500 to 720 ° C. A hot-rolled steel sheet was obtained. The hot-rolled steel sheet was annealed and cold-rolled twice, sandwiching the intermediate annealing or once, to produce a cold-rolled steel sheet having a thickness of 1.0 to 2.0 mm. All the obtained cold-rolled steel sheets were subjected to finish annealing at a temperature of 850 to 1050 ° C. at which recrystallization was completed.
The components of the steel were also carried out in the range defined by the present invention (the component of the present invention) and the other range (comparative component). Manufacturing conditions were also carried out under the preferable conditions (invention examples) limited in the present invention and other conditions (comparative examples). As reference examples, commercially available SUS430J1L (19% Cr-0.5% Nb steel) and SUS436J1L (18Cr-1Mo steel) were used.
得られた鋼板から各種の試験片を採取し、以下のような試験を行い、鋼板の特性を調査し、評価した。
高温強度(TS、0.2%PS)は、平行部長さ40mm、幅12.5mmの引張試験片を圧延方向から採取して高温引張試験により求めた。高温引張試験は800℃で行い、引張速度は0.2%耐力まで0.09mm/min,以降3mm/minとした。
耐酸化性は20mm×25mmの試験片を採取し、表裏面・端面を湿式#600研磨仕上げとして大気中980℃、200hr連続酸化試験により評価した。その評価指標は、表面皮膜の(i)剥離および(ii)異常酸化の発生有無とした。
(i)の表面皮膜の剥離は、点状に発生する色調の変化、(ii)の異常酸化は、表面の保護性皮膜が破壊されてFe酸化物を主体とするこぶ状の酸化形態が確認された場合とした。本連続酸化試験条件において参考例としたSUS430J1L及びSUS436JLでは表面皮膜の剥離が見られ、一部では異常酸化に至った。従って、本発明の目標は、980℃、200hr連続酸化試験で異常酸化が発生しない耐酸化性を有し、かつ参考例と同等以上の高温強度(800℃での0.2%PS≧35MPa,T,S≧55MPa)を兼備するものとした。
Various test pieces were collected from the obtained steel sheet, and the following tests were conducted to investigate and evaluate the characteristics of the steel sheet.
The high temperature strength (TS, 0.2% PS) was determined by a high temperature tensile test by collecting a tensile test piece having a parallel part length of 40 mm and a width of 12.5 mm from the rolling direction. The high temperature tensile test was performed at 800 ° C., and the tensile speed was 0.09 mm / min up to 0.2% proof stress, and thereafter 3 mm / min.
The oxidation resistance was evaluated by taking a 20 mm × 25 mm test piece, and subjecting the front and back surfaces and end surfaces to a wet # 600 polishing finish in the atmosphere at 980 ° C. for 200 hours. The evaluation index was (i) peeling of the surface film and (ii) occurrence of abnormal oxidation.
The peeling of the surface film in (i) is a change in the color tone generated in a dot-like manner, and the abnormal oxidation in (ii) is confirmed to be a lumpy oxidation form mainly composed of Fe oxide due to destruction of the protective film on the surface. Was the case. In SUS430J1L and SUS436JL, which were used as reference examples in the continuous oxidation test conditions, peeling of the surface film was observed, and in part, abnormal oxidation occurred. Therefore, the goal of the present invention is to have an oxidation resistance that does not cause abnormal oxidation in a continuous oxidation test at 980 ° C. for 200 hours and has a high temperature strength equal to or higher than that of the reference example (0.2% PS ≧ 35 MPa at 800 ° C., T, S ≧ 55 MPa).
表2に各試験結果をまとめて示す。
表2から、試験番号1,5,7,8,11〜15は、本発明で規定する成分と好適な製造方法(熱延条件、熱延板焼鈍条件)を全て満足する高純度フェライト系ステンレス鋼である。これら鋼板は、SUS430J1LやSUS436J1Lを上回る高温強度と耐酸化性が得られたものである。
Table 2 summarizes the test results.
From Table 2,
試験番号2,3,4,6,9,10は、本発明で規定する成分を有し,本発明の好適な製造方法(熱延条件、熱延板焼鈍条件)から一部及び全て外れるものである。しかしながら、これらの鋼板は本発明の目標とするSUS430J1LやSUS436J1Lと同等の高温強度と耐酸化性が得られたものである。また、試験番号13は、Nの量が他の鋼と比べて多く、段落〔0014〕で述べた本発明で好適な高純度化から外れてはいるが本発明の範囲の組成を有し、本発明の目標とする特性を有する場合である。 Test Nos. 2, 3, 4, 6, 9, and 10 have the components specified in the present invention, and partly or completely deviate from the preferred manufacturing method (hot rolling conditions, hot rolled sheet annealing conditions) of the present invention. It is. However, these steel sheets have high temperature strength and oxidation resistance equivalent to SUS430J1L and SUS436J1L, which are the targets of the present invention. Test No. 13 has a larger amount of N than other steels, and has a composition within the scope of the present invention, although it is out of the high purity suitable for the present invention described in paragraph [0014]. This is a case having the target characteristics of the present invention.
試験番号16〜21は、本発明の好適な製造方法(熱延条件、熱延板焼鈍条件)を実施しているものの、本発明の成分から外れるものである。これら鋼板は、本発明で目標とする高温強度と耐酸化性が得られなかった。 Although test numbers 16-21 are implementing the suitable manufacturing method (hot-rolling conditions, hot-rolled sheet annealing conditions) of this invention, it remove | deviates from the component of this invention. These steel plates did not achieve the high temperature strength and oxidation resistance targeted by the present invention.
図1は、表1に示される実施例1の鋼のCr、Sn、Al量と表2に示される耐酸化性の関係を示している。本発明の目標とする耐酸化性が得られたものを「○」、耐酸化性の評価が参考例と同等以下のものを「×」と表記した。本結果から、Sn添加により高温強度に加えて、良好な耐酸化性を得るには、本発明で規定する成分範囲(Cr、Sn,Al)とする調整が重要である。 FIG. 1 shows the relationship between the Cr, Sn, and Al amounts of the steel of Example 1 shown in Table 1 and the oxidation resistance shown in Table 2. “O” indicates that the target oxidation resistance of the present invention was obtained, and “x” indicates that the evaluation of oxidation resistance is equal to or less than that of the reference example. From this result, in order to obtain good oxidation resistance in addition to high-temperature strength by adding Sn, it is important to adjust the component range (Cr, Sn, Al) defined in the present invention.
本発明によれば、製造性や溶接性を阻害するAlやSiの過度の合金化やNb,Mo,W,希土類等の希少元素の添加に頼ることなく、微量Sn添加を活用して耐酸化性と高温強度を既存耐熱鋼と同等以上に向上した省合金型の高純度フェライト系ステンレス鋼板を得ることができる。 According to the present invention, oxidation resistance by utilizing a small amount of Sn addition without relying on excessive alloying of Al or Si which impedes manufacturability or weldability, or addition of rare elements such as Nb, Mo, W, rare earth, etc. It is possible to obtain an alloy-saving high-purity ferritic stainless steel sheet with improved properties and high-temperature strength equal to or better than those of existing heat-resistant steel.
Claims (7)
800℃での0.2%耐力が35MPa以上であって、引張強さが55MPa以上であることを特徴とする耐酸化性と高温強度に優れた高純度フェライト系ステンレス鋼板。 In mass%, C: 0.001 to 0.03%, Si: 0.01 to 2%, Mn: 0.01 to 1.5%, P: 0.005 to 0.05%, S: 0 0.0001-0.01%, Cr: 16-30%, N: 0.001-0.03%, Al: 0.05-0.8%, Sn: 0.01-1%, the balance being Fe and Ri Do unavoidable impurities,
A 800 0.2% yield strength of at ℃ is 35MPa or more, tensile strength of the high-purity ferritic stainless steel sheet excellent in oxidation resistance and high temperature strength, characterized in der Rukoto least 55 MPa.
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